/*
 #
 #  File            : CImg.h
 #                    ( C++ header file )
 #
 #  Description     : C++ Template Image Processing Toolkit.
 #                    This file is the main component of the CImg Library project.
 #                    ( http://cimg.eu )
 #
 #  Project manager : David Tschumperlé
 #                    ( http://tschumperle.users.greyc.fr/ )
 #
 #                    A complete list of contributors is available in file 'README.txt'
 #                    distributed within the CImg package.
 #
 #  Licenses        : This file is 'dual-licensed', you have to choose one
 #                    of the two licenses below to apply.
 #
 #                    CeCILL-C
 #                    The CeCILL-C license is close to the GNU LGPL.
 #                    ( http://cecill.info/licences/Licence_CeCILL-C_V1-en.html )
 #
 #                or  CeCILL v2.1
 #                    The CeCILL license is compatible with the GNU GPL.
 #                    ( http://cecill.info/licences/Licence_CeCILL_V2.1-en.html )
 #
 #  This software is governed either by the CeCILL or the CeCILL-C license
 #  under French law and abiding by the rules of distribution of free software.
 #  You can  use, modify and or redistribute the software under the terms of
 #  the CeCILL or CeCILL-C licenses as circulated by CEA, CNRS and INRIA
 #  at the following URL: "http://cecill.info".
 #
 #  As a counterpart to the access to the source code and  rights to copy,
 #  modify and redistribute granted by the license, users are provided only
 #  with a limited warranty  and the software's author,  the holder of the
 #  economic rights,  and the successive licensors  have only  limited
 #  liability.
 #
 #  In this respect, the user's attention is drawn to the risks associated
 #  with loading,  using,  modifying and/or developing or reproducing the
 #  software by the user in light of its specific status of free software,
 #  that may mean  that it is complicated to manipulate,  and  that  also
 #  therefore means  that it is reserved for developers  and  experienced
 #  professionals having in-depth computer knowledge. Users are therefore
 #  encouraged to load and test the software's suitability as regards their
 #  requirements in conditions enabling the security of their systems and/or
 #  data to be ensured and,  more generally, to use and operate it in the
 #  same conditions as regards security.
 #
 #  The fact that you are presently reading this means that you have had
 #  knowledge of the CeCILL and CeCILL-C licenses and that you accept its terms.
 #
*/

// Set version number of the library.
#ifndef cimg_version
#define cimg_version 401

/*-----------------------------------------------------------
 #
 # Test and possibly auto-set CImg configuration variables
 # and include required headers.
 #
 # If you find that the default configuration variables are
 # not adapted to your system, you can override their values
 # before including the header file "CImg.h"
 # (use the #define directive).
 #
 ------------------------------------------------------------*/

// Include standard C++ headers.
// This is the minimal set of required headers to make CImg-based codes compile.
#include <cstdio>
#include <cstdlib>
#include <cstdarg>
#include <cstring>
#include <cmath>
#include <cfloat>
#include <climits>
#include <ctime>
#include <exception>
#include <algorithm>
#define cimg_str(x) #x
#define cimg_str2(x) cimg_str(x)

// Detect/configure OS variables.
//
// Define 'cimg_OS' to: '0' for an unknown OS (will try to minimize library dependencies).
//                      '1' for a Unix-like OS (Linux, Solaris, BSD, MacOSX, Irix, ...).
//                      '2' for Microsoft Windows.
//                      (auto-detection is performed if 'cimg_OS' is not set by the user).
#ifndef cimg_OS
#if defined(unix)        || defined(__unix)      || defined(__unix__) \
 || defined(linux)       || defined(__linux)     || defined(__linux__) \
 || defined(sun)         || defined(__sun) \
 || defined(BSD)         || defined(__OpenBSD__) || defined(__NetBSD__) \
 || defined(__FreeBSD__) || defined (__DragonFly__) \
 || defined(sgi)         || defined(__sgi) \
 || defined(__OSX__)     || defined(__MACOSX__)  || defined(__APPLE__) \
 || defined(__CYGWIN__)
#define cimg_OS 1
#elif defined(_MSC_VER) || defined(WIN32)  || defined(_WIN32) || defined(__WIN32__) \
   || defined(WIN64)    || defined(_WIN64) || defined(__WIN64__)
#define cimg_OS 2
#else
#define cimg_OS 0
#endif
#elif !(cimg_OS==0 || cimg_OS==1 || cimg_OS==2)
#error CImg Library: Invalid configuration variable 'cimg_OS'.
#error (correct values are '0 = unknown OS', '1 = Unix-like OS', '2 = Microsoft Windows').
#endif
#ifndef cimg_date
#define cimg_date __DATE__
#endif
#ifndef cimg_time
#define cimg_time __TIME__
#endif

// Suppress minor warnings on some Microsoft and GCC compilers
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4127)
#pragma warning(disable:4244)
#pragma warning(disable:4307)
#pragma warning(disable:4311)
#pragma warning(disable:4312)
#pragma warning(disable:4319)
#pragma warning(disable:4512)
#pragma warning(disable:4571)
#pragma warning(disable:4640)
#pragma warning(disable:4702)
#pragma warning(disable:4706)
#pragma warning(disable:4710)
#pragma warning(disable:4800)
#pragma warning(disable:4804)
#pragma warning(disable:4820)
#pragma warning(disable:4995)
#pragma warning(disable:4996)

#ifndef _CRT_SECURE_NO_DEPRECATE
#define _CRT_SECURE_NO_DEPRECATE 1
#endif
#ifndef _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS 1
#endif
#ifndef _CRT_NONSTDC_NO_DEPRECATE
#define _CRT_NONSTDC_NO_DEPRECATE 1
#endif
#endif

#if __GNUC__>10
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-truncation"
#pragma GCC diagnostic ignored "-Wformat-overflow"
#endif

// Define correct string functions for each compiler and OS.
#if cimg_OS==2 && defined(_MSC_VER)
#define cimg_sscanf std::sscanf
#define cimg_snprintf cimg::_snprintf
#define cimg_vsnprintf cimg::_vsnprintf
#else
#include <stdio.h>
#if defined(__MACOSX__) || defined(__APPLE__)
#define cimg_sscanf cimg::_sscanf
#define cimg_snprintf cimg::_snprintf
#define cimg_vsnprintf cimg::_vsnprintf
#else
#define cimg_sscanf std::sscanf
#define cimg_snprintf snprintf
#define cimg_vsnprintf vsnprintf
#endif
#endif

// Include OS-specific headers.
#if cimg_OS==1
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <fnmatch.h>
#elif cimg_OS==2
#ifndef NOMINMAX
#define NOMINMAX
#endif
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#ifndef _WIN32_IE
#define _WIN32_IE 0x0400
#endif
#include <shlobj.h>
#include <process.h>
#include <io.h>
enum {FALSE_WIN = 0};
#endif

// Check for C++11 support.
#ifndef cimg_use_cpp11
#if __cplusplus>201100L || (defined(_MSVC_LANG) && _MSVC_LANG>=201103L)
#define cimg_use_cpp11 1
#else
#define cimg_use_cpp11 0
#endif
#endif
#if cimg_use_cpp11==1
#include <initializer_list>
#include <utility>
#endif

#if cimg_use_cpp11==1
#define cimg_noexcept noexcept
#else
#define cimg_noexcept throw()
#endif

// Portable macro to define 'pragma'.
#ifdef _MSC_VER
#define cimg_pragma(x) __pragma(x)
#else
#define cimg_pragma(x) _Pragma(#x)
#endif

// Define custom datatypes to ensure portability.
// ( 'sizeof(cimg_ulong/cimg_long) = sizeof(void*)' ).
#define cimg_uint8 unsigned char
#if defined(CHAR_MAX) && CHAR_MAX==255
#define cimg_int8 signed char
#else
#define cimg_int8 char
#endif
#define cimg_uint16 unsigned short
#define cimg_int16 short
#define cimg_uint32 unsigned int
#define cimg_int32 int
#define cimg_float32 float
#define cimg_float64 double

#if cimg_OS==2

#define cimg_uint64 unsigned __int64
#define cimg_int64 __int64
#define cimg_ulong UINT_PTR
#define cimg_long INT_PTR
#ifdef _MSC_VER
#define cimg_fuint64 "%I64u"
#define cimg_fint64 "%I64d"
#else
#define cimg_fuint64 "%llu"
#define cimg_fint64 "%lld"
#endif
#define cimg_fhex64 "%llx"

#else

#if UINTPTR_MAX==0xffffffff || defined(__arm__) || defined(_M_ARM) || ((ULONG_MAX)==(UINT_MAX))
#define cimg_uint64 unsigned long long
#define cimg_int64 long long
#define cimg_fuint64 "%llu"
#define cimg_fint64 "%lld"
#define cimg_fhex64 "%llx"
#else
#define cimg_uint64 unsigned long
#define cimg_int64 long
#define cimg_fuint64 "%lu"
#define cimg_fint64 "%ld"
#define cimg_fhex64 "%lx"
#endif

#if defined(__arm__) || defined(_M_ARM)
#define cimg_ulong unsigned long long
#define cimg_long long long
#else
#define cimg_ulong unsigned long
#define cimg_long long
#endif

#endif

#ifndef cimg_max_buf_size
#if UINTPTR_MAX==0xffffffff
#define cimg_max_buf_size ((cimg_ulong)3*1024*1024*1024)
#else
#define cimg_max_buf_size ((cimg_ulong)16*1024*1024*1024)
#endif
#endif

// Configure filename separator.
//
// The directory separator is set to '/' by default, except on Windows where it is '\'.
#ifndef cimg_directory_separator
#if cimg_OS==2
#define cimg_directory_separator '\\'
#else
#define cimg_directory_separator '/'
#endif
#endif

// Configure verbosity of output messages.
//
// Define 'cimg_verbosity' to: '0' to hide library messages (quiet mode).
//                             '1' to print library messages on the console.
//                             '2' to print library messages on a basic dialog window (default behavior).
//                             '3' equivalent to '1' with warnings (may slow down the code!).
//                             '4' equivalent to '2' with warnings (may slow down the code!).
//
// Define 'cimg_strict_warnings' to throw exceptions instead of displaying warning messages.
//
// Define 'cimg_use_vt100' to allow output of color messages on VT100-compatible terminals.
#ifndef cimg_verbosity
#if cimg_OS==2
#define cimg_verbosity 2
#else
#define cimg_verbosity 1
#endif
#elif !(cimg_verbosity==0 || cimg_verbosity==1 || cimg_verbosity==2 || cimg_verbosity==3 || cimg_verbosity==4)
#error CImg Library: Configuration variable 'cimg_verbosity' is badly defined.
#error (should be { 0=quiet | 1=console | 2=dialog | 3=console+warnings | 4=dialog+warnings }).
#endif

// Configure OpenMP support.
// (http://www.openmp.org)
//
// Define 'cimg_use_openmp' to enable OpenMP support (requires OpenMP 3.0+).
//
// OpenMP directives are used in many CImg functions to leverage multi-core CPUs.
#if !defined(cimg_use_openmp)
#ifdef _OPENMP
#define cimg_use_openmp 1
#else
#define cimg_use_openmp 0
#endif
#else
#undef cimg_use_openmp
#define cimg_use_openmp 1
#endif
#if cimg_use_openmp!=0
#include <omp.h>
#define cimg_pragma_openmp(p) cimg_pragma(omp p)
#else
#define cimg_pragma_openmp(p)
#endif

// Configure the 'abort' signal handler (does nothing by default).
// A typical signal handler can be defined in your own source like this:
// #define cimg_abort_test if (is_abort) throw CImgAbortException("")
//
// where 'is_abort' is a boolean variable defined somewhere in your code and reachable in the function.
// 'cimg_abort_test2' does the same but is called more often (in inner loops).
#if defined(cimg_abort_test) && cimg_use_openmp!=0

// Define abort macros to be used with OpenMP.
#ifndef _cimg_abort_init_openmp
#define _cimg_abort_init_openmp \
  unsigned int _cimg_abort_go_openmp = 1; \
  cimg_library::cimg::unused(_cimg_abort_go_openmp)
#endif
#ifndef _cimg_abort_try_openmp
#define _cimg_abort_try_openmp if (_cimg_abort_go_openmp) try
#endif
#ifndef _cimg_abort_catch_openmp
#define _cimg_abort_catch_openmp catch (CImgAbortException&) { \
  cimg_pragma_openmp(atomic) _cimg_abort_go_openmp&=0; \
}
#endif
#ifndef _cimg_abort_catch_fill_openmp
#define _cimg_abort_catch_fill_openmp \
  catch (CImgException& e) { cimg_pragma(omp critical(abort)) CImg<charT>::string(e._message).move_to(is_error_expr); \
                             cimg_pragma_openmp(atomic) _cimg_abort_go_openmp&=0; }
#endif
#ifdef cimg_abort_test2
#ifndef _cimg_abort_try_openmp2
#define _cimg_abort_try_openmp2 _cimg_abort_try_openmp
#endif
#ifndef _cimg_abort_catch_openmp2
#define _cimg_abort_catch_openmp2 _cimg_abort_catch_openmp
#endif
#endif
#endif

#ifndef _cimg_abort_init_openmp
#define _cimg_abort_init_openmp
#endif
#ifndef _cimg_abort_try_openmp
#define _cimg_abort_try_openmp
#endif
#ifndef _cimg_abort_catch_openmp
#define _cimg_abort_catch_openmp
#endif
#ifndef _cimg_abort_try_openmp2
#define _cimg_abort_try_openmp2
#endif
#ifndef _cimg_abort_catch_openmp2
#define _cimg_abort_catch_openmp2
#endif
#ifndef _cimg_abort_catch_fill_openmp
#define _cimg_abort_catch_fill_openmp
#endif
#ifndef cimg_abort_init
#define cimg_abort_init
#endif
#ifndef cimg_abort_test
#define cimg_abort_test
#endif
#ifndef cimg_abort_test2
#define cimg_abort_test2
#endif

// Configure display framework.
//
// Define 'cimg_display' to: '0' to disable display capabilities.
//                           '1' to use the X-Window framework (X11).
//                           '2' to use the Microsoft GDI32 framework.
//                           '3' to use SDL3 framework.
#ifndef cimg_display
#if cimg_OS==0
#define cimg_display 0
#elif cimg_OS==1
#define cimg_display 1
#elif cimg_OS==2
#define cimg_display 2
#endif
#elif !(cimg_display==0 || cimg_display==1 || cimg_display==2 || cimg_display==3)
#error CImg Library: Configuration variable 'cimg_display' is badly defined.
#error (should be { 0=none | 1=X-Window (X11) | 2=Microsoft GDI32 | 3=SDL3 }).
#endif

// Include display-specific headers.
#if cimg_display==1
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>
#include <pthread.h>
#ifdef cimg_use_xshm
#include <sys/ipc.h>
#include <sys/shm.h>
#include <X11/extensions/XShm.h>
#endif
#ifdef cimg_use_xrandr
#include <X11/extensions/Xrandr.h>
#endif
#elif cimg_display==3
#include <SDL3/SDL.h>
#include <pthread.h>
#if cimg_OS==1
#include <csignal>
#endif
#endif

#ifndef cimg_appname
#define cimg_appname "CImg"
#endif

// Configure OpenCV support.
// (http://opencv.willowgarage.com/wiki/)
//
// Define 'cimg_use_opencv' to enable OpenCV support.
//
// OpenCV library may be used to access images from cameras.
// (see function 'CImg<T>::load_camera()').
#ifdef cimg_use_opencv
#ifdef True
#undef True
#define _cimg_redefine_True
#endif
#ifdef False
#undef False
#define _cimg_redefine_False
#endif
#ifdef Status
#undef Status
#define _cimg_redefine_Status
#endif
#include <cstddef>
#include <opencv2/opencv.hpp>
#if CV_MAJOR_VERSION>=3
#define _cimg_fourcc cv::VideoWriter::fourcc
#define _cimg_cap_prop_frame_width cv::VideoCaptureProperties::CAP_PROP_FRAME_WIDTH
#define _cimg_cap_prop_frame_height cv::VideoCaptureProperties::CAP_PROP_FRAME_HEIGHT
#define _cimg_cap_prop_frame_count cv::VideoCaptureProperties::CAP_PROP_FRAME_COUNT
#else
#define _cimg_fourcc CV_FOURCC
#define _cimg_cap_prop_frame_width CV_CAP_PROP_FRAME_WIDTH
#define _cimg_cap_prop_frame_height CV_CAP_PROP_FRAME_HEIGHT
#define _cimg_cap_prop_frame_count CV_CAP_PROP_FRAME_COUNT
#endif
#endif

// Configure LibPNG support.
// (http://www.libpng.org)
//
// Define 'cimg_use_png' to enable LibPNG support.
//
// PNG library may be used to get native support for '.png' files.
// (see functions 'CImg<T>::{load,save}_png()').
#ifdef cimg_use_png
extern "C" {
#include "png.h"
}
#endif

// Configure LibJPEG support.
// (http://en.wikipedia.org/wiki/Libjpeg)
//
// Define 'cimg_use_jpeg' to enable LibJPEG support.
//
// JPEG library may be used to get native support for '.jpg' files.
// (see functions 'CImg<T>::{load,save}_jpeg()').
#ifdef cimg_use_jpeg
extern "C" {
#include "jpeglib.h"
#include "setjmp.h"
}
#endif

// Configure JPEG XL support.
// (https://en.wikipedia.org/wiki/JPEG_XL)
//
// Define 'cimg_use_jxl' to enable JPEG XL support.
//
// Libjxl may be used to get native support for '.jxl' files.
// (see functions 'CImg<T>::{load,save}_jxl()').
#ifdef cimg_use_jxl
#include <jxl/decode.h>
#include <jxl/encode.h>
#endif

// Configure LibTIFF support.
// (http://www.libtiff.org)
//
// Define 'cimg_use_tiff' to enable LibTIFF support.
//
// TIFF library may be used to get native support for '.tif' files.
// (see functions 'CImg[List]<T>::{load,save}_tiff()').
#ifdef cimg_use_tiff
extern "C" {
#define uint64 uint64_hack_
#define int64 int64_hack_
#include "tiffio.h"
#undef uint64
#undef int64
}
#endif

// Configure HEIF support.
// (https://github.com/strukturag/libheif)
//
// Define 'cimg_use_heif' to enable HEIF support.
//
// HEIF library may be used to get native support for '.heic' and '.avif' files.
// (see function 'CImg<T>::load_heif()').
#ifdef cimg_use_heif
#include <libheif/heif_cxx.h>
#endif

// Configure WebP support.
// (https://chromium.googlesource.com/webm/libwebp/)
//
// Define 'cimg_use_webp' to enable WebP support.
//
// WebP library may be used to get native support for '.webp' files.
// (see function 'CImg<T>::{load,save}_webp()').
#ifdef cimg_use_webp
#include <webp/decode.h>
#include <webp/encode.h>
#endif

// Configure LibMINC2 support.
// (http://en.wikibooks.org/wiki/MINC/Reference/MINC2.0_File_Format_Reference)
//
// Define 'cimg_use_minc2' to enable LibMINC2 support.
//
// MINC2 library may be used to get native support for '.mnc' files.
// (see functions 'CImg<T>::{load,save}_minc2()').
#ifdef cimg_use_minc2
#include "minc_io_simple_volume.h"
#include "minc_1_simple.h"
#include "minc_1_simple_rw.h"
#endif

// Configure Zlib support.
// (http://www.zlib.net)
//
// Define 'cimg_use_zlib' to enable Zlib support.
//
// Zlib library may be used to allow compressed data in '.cimgz' files.
// (see functions 'CImg[List]<T>::{load,save}_cimg()').
#ifdef cimg_use_zlib
extern "C" {
#include "zlib.h"
}
#endif

// Configure libcurl support.
// (http://curl.haxx.se/libcurl/)
//
// Define 'cimg_use_curl' to enable libcurl support.
//
// Libcurl may be used to get native support for files downloaded from the network.
// (see function 'cimg::load_network()').
#ifdef cimg_use_curl
#include "curl/curl.h"
#endif

// Configure Magick++ support.
// (http://www.imagemagick.org/Magick++)
//
// Define 'cimg_use_magick' to enable Magick++ support.
//
// Magick++ library may be used to get native support for various image file formats.
// (see functions 'CImg<T>::{load,save}()').
#ifdef cimg_use_magick
#include "Magick++.h"
#endif

// Configure FFTW3 support.
// (http://www.fftw.org)
//
// Define 'cimg_use_fftw3' to enable libFFTW3 support.
//
// FFTW3 library may be used to efficiently compute the Fast Fourier Transform
// of image data, without restriction on the image size.
// (see function 'CImg[List]<T>::FFT()').
#ifdef cimg_use_fftw3
extern "C" {
#include "fftw3.h"
}
#endif

// Configure OpenEXR support.
// (http://www.openexr.com/)
//
// Define 'cimg_use_openexr' to enable OpenEXR support.
//
// OpenEXR library may be used to get native support for '.exr' files.
// (see functions 'CImg<T>::{load,save}_exr()').
#ifdef cimg_use_openexr
#if __GNUC__>=5
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated"
#pragma GCC diagnostic ignored "-Wdeprecated-copy"
#pragma GCC diagnostic ignored "-Wshadow"
#endif
#include "ImfRgbaFile.h"
#include "ImfInputFile.h"
#include "ImfChannelList.h"
#include "ImfMatrixAttribute.h"
#include "ImfArray.h"
#if __GNUC__>=5
#pragma GCC diagnostic pop
#endif
#endif

// Configure TinyEXR support.
// (https://github.com/syoyo/tinyexr)
//
// Define 'cimg_use_tinyexr' to enable TinyEXR support.
//
// TinyEXR is a small, single header-only library to load and save OpenEXR(.exr) images.
#ifdef cimg_use_tinyexr
#ifndef TINYEXR_IMPLEMENTATION
#define TINYEXR_IMPLEMENTATION
#endif
#include "tinyexr.h"
#endif

// Define cimg_float16.
#if defined(_HALF_H_) || defined(cimg_use_openexr)
#define cimg_float16 half
#define cimg_is_float16 1
#else
#define cimg_is_float16 0
#endif

// Define cimg_use_pthread
#if defined(PTHREAD_H) || defined(_PTHREAD_H)
#define cimg_use_pthread 1
#else
#define cimg_use_pthread 0
#endif

// Check if min/max/PI macros are defined.
//
// CImg does not compile if 'min', 'max', or 'PI' are defined as macros because it defines the functions
// min(), max(), and the constant PI inside the 'cimg::' namespace. Therefore, it undefines these macros
// if necessary and restores them to their previous values at the end of the file.
#ifdef min
#undef min
#define _cimg_redefine_min
#endif
#ifdef max
#undef max
#define _cimg_redefine_max
#endif
#ifdef PI
#undef PI
#define _cimg_redefine_PI
#endif

/*------------------------------------------------------------------------------
  #
  # Define user-friendly macros.
  #
  # These CImg macros are prefixed by 'cimg_' and can be used safely in your own
  # code. They are useful to parse command line options, or to write image loops.
  #
  ------------------------------------------------------------------------------*/

// Macros to define program usage, and retrieve command line arguments.
#define cimg_usage(usage) cimg_library::cimg::option((char*)0,argc,argv,(char*)0,usage,false)
#define cimg_help(str) cimg_library::cimg::option((char*)0,argc,argv,str,(char*)0)
#define cimg_option(name,_default,usage) cimg_library::cimg::option(name,argc,argv,_default,usage)

// Macros to define and manipulate local neighborhoods.
#define CImg_2x2(I,T) T I[4] = {}; \
                      T& I##cc = I[0]; T& I##nc = I[1]; \
                      T& I##cn = I[2]; T& I##nn = I[3]; \
                      cimg_library::cimg::unused(I##cc,I##nc,I##cn,I##nn)

#define CImg_3x3(I,T) T I[9] = {}; \
                      T& I##pp = I[0]; T& I##cp = I[1]; T& I##np = I[2]; \
                      T& I##pc = I[3]; T& I##cc = I[4]; T& I##nc = I[5]; \
                      T& I##pn = I[6]; T& I##cn = I[7]; T& I##nn = I[8]; \
                      cimg_library::cimg::unused(I##pp,I##cp,I##np,I##pc,I##cc,I##nc); \
                      cimg_library::cimg::unused(I##pn,I##cn,I##nn)

#define CImg_4x4(I,T) T I[16] = {}; \
                      T& I##pp = I[0]; T& I##cp = I[1]; T& I##np = I[2]; T& I##ap = I[3]; \
                      T& I##pc = I[4]; T& I##cc = I[5]; T& I##nc = I[6]; T& I##ac = I[7]; \
                      T& I##pn = I[8]; T& I##cn = I[9]; T& I##nn = I[10]; T& I##an = I[11]; \
                      T& I##pa = I[12]; T& I##ca = I[13]; T& I##na = I[14]; T& I##aa = I[15]; \
                      cimg_library::cimg::unused(I##pp,I##cp,I##np,I##ap); \
                      cimg_library::cimg::unused(I##pc,I##cc,I##nc,I##ac); \
                      cimg_library::cimg::unused(I##pn,I##cn,I##nn,I##an); \
                      cimg_library::cimg::unused(I##pa,I##ca,I##na,I##aa)

#define CImg_5x5(I,T) T I[25] = {}; \
                      T& I##bb = I[0]; T& I##pb = I[1]; T& I##cb = I[2]; T& I##nb = I[3]; T& I##ab = I[4]; \
                      T& I##bp = I[5]; T& I##pp = I[6]; T& I##cp = I[7]; T& I##np = I[8]; T& I##ap = I[9]; \
                      T& I##bc = I[10]; T& I##pc = I[11]; T& I##cc = I[12]; T& I##nc = I[13]; T& I##ac = I[14]; \
                      T& I##bn = I[15]; T& I##pn = I[16]; T& I##cn = I[17]; T& I##nn = I[18]; T& I##an = I[19]; \
                      T& I##ba = I[20]; T& I##pa = I[21]; T& I##ca = I[22]; T& I##na = I[23]; T& I##aa = I[24]; \
                      cimg_library::cimg::unused(I##bb,I##pb,I##cb,I##nb,I##ab); \
                      cimg_library::cimg::unused(I##bp,I##pp,I##cp,I##np,I##ap); \
                      cimg_library::cimg::unused(I##bc,I##pc,I##cc,I##nc,I##ac); \
                      cimg_library::cimg::unused(I##bn,I##pn,I##cn,I##nn,I##an); \
                      cimg_library::cimg::unused(I##ba,I##pa,I##ca,I##na,I##aa)

#define CImg_2x2x2(I,T) T I[8] = {}; \
                      T& I##ccc = I[0]; T& I##ncc = I[1]; \
                      T& I##cnc = I[2]; T& I##nnc = I[3]; \
                      T& I##ccn = I[4]; T& I##ncn = I[5]; \
                      T& I##cnn = I[6]; T& I##nnn = I[7]; \
                      cimg_library::cimg::unused(I##ccc,I##ncc,I##cnc,I##nnc); \
                      cimg_library::cimg::unused(I##ccn,I##ncn,I##cnn,I##nnn)

#define CImg_3x3x3(I,T) T I[27] = {}; \
                      T& I##ppp = I[0]; T& I##cpp = I[1]; T& I##npp = I[2]; \
                      T& I##pcp = I[3]; T& I##ccp = I[4]; T& I##ncp = I[5]; \
                      T& I##pnp = I[6]; T& I##cnp = I[7]; T& I##nnp = I[8]; \
                      T& I##ppc = I[9]; T& I##cpc = I[10]; T& I##npc = I[11]; \
                      T& I##pcc = I[12]; T& I##ccc = I[13]; T& I##ncc = I[14]; \
                      T& I##pnc = I[15]; T& I##cnc = I[16]; T& I##nnc = I[17]; \
                      T& I##ppn = I[18]; T& I##cpn = I[19]; T& I##npn = I[20]; \
                      T& I##pcn = I[21]; T& I##ccn = I[22]; T& I##ncn = I[23]; \
                      T& I##pnn = I[24]; T& I##cnn = I[25]; T& I##nnn = I[26]; \
                      cimg_library::cimg::unused(I##ppp,I##cpp,I##npp,I##pcp,I##ccp,I##ncp); \
                      cimg_library::cimg::unused(I##pnp,I##cnp,I##nnp,I##ppc,I##cpc,I##npc); \
                      cimg_library::cimg::unused(I##pcc,I##ccc,I##ncc,I##pnc,I##cnc,I##nnc); \
                      cimg_library::cimg::unused(I##ppn,I##cpn,I##npn,I##pcn,I##ccn,I##ncn); \
                      cimg_library::cimg::unused(I##pnn,I##cnn,I##nnn)

#define cimg_def2x2(img,x,y) \
  int _n1##x = x<(img).width() - 1?x + 1:(img).width() - 1, \
      _n1##y = y<(img).height() - 1?y + 1:(img).height() - 1

#define cimg_def3x3(img,x,y) \
  cimg_def2x2(img,x,y); \
  int _p1##x = x>1?x - 1:0, \
      _p1##y = y>1?y - 1:0

#define cimg_def4x4(img,x,y) \
  cimg_def3x3(img,x,y); \
  int _n2##x = x<(img).width() - 2?x + 2:(img).width() - 1, \
      _n2##y = y<(img).height() - 2?y + 2:(img).height() - 1

#define cimg_def5x5(img,x,y) \
  cimg_def4x4(img,x,y); \
  int _p2##x = x>2?x - 2:0, \
      _p2##y = y>2?y - 2:0

#define cimg_def6x6(img,x,y) \
  cimg_def5x5(img,x,y); \
  int _n3##x = x<(img).width() - 3?x + 3:(img).width() - 1, \
      _n3##y = y<(img).height() - 3?y + 3:(img).height() - 1

#define cimg_def7x7(img,x,y) \
  cimg_def6x6(img,x,y); \
  int _p3##x = x>3?x - 3:0, \
      _p3##y = y>3?y - 3:0

#define cimg_def8x8(img,x,y) \
  cimg_def7x7(img,x,y); \
  int _n4##x = x<(img).width() - 4?x + 4:(img).width() - 1, \
      _n4##y = y<(img).height() - 4?y + 4:(img).height() - 1

#define cimg_def9x9(img,x,y) \
  cimg_def8x8(img,x,y); \
  int _p4##x = x>4?x - 4:0, \
      _p4##y = y>4?y - 4:0

#define cimg_def2x2x2(img,x,y,z) \
  cimg_def2x2(img,x,y); \
  int _n1##z = z<(img).depth() - 1?z + 1:(img).depth() - 1

#define cimg_def3x3x3(img,x,y,z) \
  cimg_def2x2x2(img,x,y,z); \
  int _p1##x = x>1?x - 1:0, \
      _p1##y = y>1?y - 1:0, \
      _p1##z = z>1?z - 1:0

#define cimg_get2x2(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(x,y,z,c), I[1] = (T)(img)(_n1##x,y,z,c), I[2] = (T)(img)(x,_n1##y,z,c), \
  I[3] = (T)(img)(_n1##x,_n1##y,z,c)

#define cimg_get3x3(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p1##x,_p1##y,z,c), I[1] = (T)(img)(x,_p1##y,z,c), I[2] = (T)(img)(_n1##x,_p1##y,z,c), \
  I[3] = (T)(img)(_p1##x,y,z,c), I[4] = (T)(img)(x,y,z,c), I[5] = (T)(img)(_n1##x,y,z,c), \
  I[6] = (T)(img)(_p1##x,_n1##y,z,c), I[7] = (T)(img)(x,_n1##y,z,c), I[8] = (T)(img)(_n1##x,_n1##y,z,c)

#define cimg_get4x4(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p1##x,_p1##y,z,c), I[1] = (T)(img)(x,_p1##y,z,c), I[2] = (T)(img)(_n1##x,_p1##y,z,c), \
  I[3] = (T)(img)(_n2##x,_p1##y,z,c), I[4] = (T)(img)(_p1##x,y,z,c), I[5] = (T)(img)(x,y,z,c), \
  I[6] = (T)(img)(_n1##x,y,z,c), I[7] = (T)(img)(_n2##x,y,z,c), I[8] = (T)(img)(_p1##x,_n1##y,z,c), \
  I[9] = (T)(img)(x,_n1##y,z,c), I[10] = (T)(img)(_n1##x,_n1##y,z,c), I[11] = (T)(img)(_n2##x,_n1##y,z,c), \
  I[12] = (T)(img)(_p1##x,_n2##y,z,c), I[13] = (T)(img)(x,_n2##y,z,c), I[14] = (T)(img)(_n1##x,_n2##y,z,c), \
  I[15] = (T)(img)(_n2##x,_n2##y,z,c)

#define cimg_get5x5(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p2##x,_p2##y,z,c), I[1] = (T)(img)(_p1##x,_p2##y,z,c), I[2] = (T)(img)(x,_p2##y,z,c), \
  I[3] = (T)(img)(_n1##x,_p2##y,z,c), I[4] = (T)(img)(_n2##x,_p2##y,z,c), I[5] = (T)(img)(_p2##x,_p1##y,z,c), \
  I[6] = (T)(img)(_p1##x,_p1##y,z,c), I[7] = (T)(img)(x,_p1##y,z,c), I[8] = (T)(img)(_n1##x,_p1##y,z,c), \
  I[9] = (T)(img)(_n2##x,_p1##y,z,c), I[10] = (T)(img)(_p2##x,y,z,c), I[11] = (T)(img)(_p1##x,y,z,c), \
  I[12] = (T)(img)(x,y,z,c), I[13] = (T)(img)(_n1##x,y,z,c), I[14] = (T)(img)(_n2##x,y,z,c), \
  I[15] = (T)(img)(_p2##x,_n1##y,z,c), I[16] = (T)(img)(_p1##x,_n1##y,z,c), I[17] = (T)(img)(x,_n1##y,z,c), \
  I[18] = (T)(img)(_n1##x,_n1##y,z,c), I[19] = (T)(img)(_n2##x,_n1##y,z,c), I[20] = (T)(img)(_p2##x,_n2##y,z,c), \
  I[21] = (T)(img)(_p1##x,_n2##y,z,c), I[22] = (T)(img)(x,_n2##y,z,c), I[23] = (T)(img)(_n1##x,_n2##y,z,c), \
  I[24] = (T)(img)(_n2##x,_n2##y,z,c)

#define cimg_get6x6(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p2##x,_p2##y,z,c), I[1] = (T)(img)(_p1##x,_p2##y,z,c), I[2] = (T)(img)(x,_p2##y,z,c), \
  I[3] = (T)(img)(_n1##x,_p2##y,z,c), I[4] = (T)(img)(_n2##x,_p2##y,z,c), I[5] = (T)(img)(_n3##x,_p2##y,z,c), \
  I[6] = (T)(img)(_p2##x,_p1##y,z,c), I[7] = (T)(img)(_p1##x,_p1##y,z,c), I[8] = (T)(img)(x,_p1##y,z,c), \
  I[9] = (T)(img)(_n1##x,_p1##y,z,c), I[10] = (T)(img)(_n2##x,_p1##y,z,c), I[11] = (T)(img)(_n3##x,_p1##y,z,c), \
  I[12] = (T)(img)(_p2##x,y,z,c), I[13] = (T)(img)(_p1##x,y,z,c), I[14] = (T)(img)(x,y,z,c), \
  I[15] = (T)(img)(_n1##x,y,z,c), I[16] = (T)(img)(_n2##x,y,z,c), I[17] = (T)(img)(_n3##x,y,z,c), \
  I[18] = (T)(img)(_p2##x,_n1##y,z,c), I[19] = (T)(img)(_p1##x,_n1##y,z,c), I[20] = (T)(img)(x,_n1##y,z,c), \
  I[21] = (T)(img)(_n1##x,_n1##y,z,c), I[22] = (T)(img)(_n2##x,_n1##y,z,c), I[23] = (T)(img)(_n3##x,_n1##y,z,c), \
  I[24] = (T)(img)(_p2##x,_n2##y,z,c), I[25] = (T)(img)(_p1##x,_n2##y,z,c), I[26] = (T)(img)(x,_n2##y,z,c), \
  I[27] = (T)(img)(_n1##x,_n2##y,z,c), I[28] = (T)(img)(_n2##x,_n2##y,z,c), I[29] = (T)(img)(_n3##x,_n2##y,z,c), \
  I[30] = (T)(img)(_p2##x,_n3##y,z,c), I[31] = (T)(img)(_p1##x,_n3##y,z,c), I[32] = (T)(img)(x,_n3##y,z,c), \
  I[33] = (T)(img)(_n1##x,_n3##y,z,c), I[34] = (T)(img)(_n2##x,_n3##y,z,c), I[35] = (T)(img)(_n3##x,_n3##y,z,c)

#define cimg_get7x7(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p3##x,_p3##y,z,c), I[1] = (T)(img)(_p2##x,_p3##y,z,c), I[2] = (T)(img)(_p1##x,_p3##y,z,c), \
  I[3] = (T)(img)(x,_p3##y,z,c), I[4] = (T)(img)(_n1##x,_p3##y,z,c), I[5] = (T)(img)(_n2##x,_p3##y,z,c), \
  I[6] = (T)(img)(_n3##x,_p3##y,z,c), I[7] = (T)(img)(_p3##x,_p2##y,z,c), I[8] = (T)(img)(_p2##x,_p2##y,z,c), \
  I[9] = (T)(img)(_p1##x,_p2##y,z,c), I[10] = (T)(img)(x,_p2##y,z,c), I[11] = (T)(img)(_n1##x,_p2##y,z,c), \
  I[12] = (T)(img)(_n2##x,_p2##y,z,c), I[13] = (T)(img)(_n3##x,_p2##y,z,c), I[14] = (T)(img)(_p3##x,_p1##y,z,c), \
  I[15] = (T)(img)(_p2##x,_p1##y,z,c), I[16] = (T)(img)(_p1##x,_p1##y,z,c), I[17] = (T)(img)(x,_p1##y,z,c), \
  I[18] = (T)(img)(_n1##x,_p1##y,z,c), I[19] = (T)(img)(_n2##x,_p1##y,z,c), I[20] = (T)(img)(_n3##x,_p1##y,z,c), \
  I[21] = (T)(img)(_p3##x,y,z,c), I[22] = (T)(img)(_p2##x,y,z,c), I[23] = (T)(img)(_p1##x,y,z,c), \
  I[24] = (T)(img)(x,y,z,c), I[25] = (T)(img)(_n1##x,y,z,c), I[26] = (T)(img)(_n2##x,y,z,c), \
  I[27] = (T)(img)(_n3##x,y,z,c), I[28] = (T)(img)(_p3##x,_n1##y,z,c), I[29] = (T)(img)(_p2##x,_n1##y,z,c), \
  I[30] = (T)(img)(_p1##x,_n1##y,z,c), I[31] = (T)(img)(x,_n1##y,z,c), I[32] = (T)(img)(_n1##x,_n1##y,z,c), \
  I[33] = (T)(img)(_n2##x,_n1##y,z,c), I[34] = (T)(img)(_n3##x,_n1##y,z,c), I[35] = (T)(img)(_p3##x,_n2##y,z,c), \
  I[36] = (T)(img)(_p2##x,_n2##y,z,c), I[37] = (T)(img)(_p1##x,_n2##y,z,c), I[38] = (T)(img)(x,_n2##y,z,c), \
  I[39] = (T)(img)(_n1##x,_n2##y,z,c), I[40] = (T)(img)(_n2##x,_n2##y,z,c), I[41] = (T)(img)(_n3##x,_n2##y,z,c), \
  I[42] = (T)(img)(_p3##x,_n3##y,z,c), I[43] = (T)(img)(_p2##x,_n3##y,z,c), I[44] = (T)(img)(_p1##x,_n3##y,z,c), \
  I[45] = (T)(img)(x,_n3##y,z,c), I[46] = (T)(img)(_n1##x,_n3##y,z,c), I[47] = (T)(img)(_n2##x,_n3##y,z,c), \
  I[48] = (T)(img)(_n3##x,_n3##y,z,c)

#define cimg_get8x8(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p3##x,_p3##y,z,c), I[1] = (T)(img)(_p2##x,_p3##y,z,c), I[2] = (T)(img)(_p1##x,_p3##y,z,c), \
  I[3] = (T)(img)(x,_p3##y,z,c), I[4] = (T)(img)(_n1##x,_p3##y,z,c), I[5] = (T)(img)(_n2##x,_p3##y,z,c), \
  I[6] = (T)(img)(_n3##x,_p3##y,z,c), I[7] = (T)(img)(_n4##x,_p3##y,z,c), I[8] = (T)(img)(_p3##x,_p2##y,z,c), \
  I[9] = (T)(img)(_p2##x,_p2##y,z,c), I[10] = (T)(img)(_p1##x,_p2##y,z,c), I[11] = (T)(img)(x,_p2##y,z,c), \
  I[12] = (T)(img)(_n1##x,_p2##y,z,c), I[13] = (T)(img)(_n2##x,_p2##y,z,c), I[14] = (T)(img)(_n3##x,_p2##y,z,c), \
  I[15] = (T)(img)(_n4##x,_p2##y,z,c), I[16] = (T)(img)(_p3##x,_p1##y,z,c), I[17] = (T)(img)(_p2##x,_p1##y,z,c), \
  I[18] = (T)(img)(_p1##x,_p1##y,z,c), I[19] = (T)(img)(x,_p1##y,z,c), I[20] = (T)(img)(_n1##x,_p1##y,z,c), \
  I[21] = (T)(img)(_n2##x,_p1##y,z,c), I[22] = (T)(img)(_n3##x,_p1##y,z,c), I[23] = (T)(img)(_n4##x,_p1##y,z,c), \
  I[24] = (T)(img)(_p3##x,y,z,c), I[25] = (T)(img)(_p2##x,y,z,c), I[26] = (T)(img)(_p1##x,y,z,c), \
  I[27] = (T)(img)(x,y,z,c), I[28] = (T)(img)(_n1##x,y,z,c), I[29] = (T)(img)(_n2##x,y,z,c), \
  I[30] = (T)(img)(_n3##x,y,z,c), I[31] = (T)(img)(_n4##x,y,z,c), I[32] = (T)(img)(_p3##x,_n1##y,z,c), \
  I[33] = (T)(img)(_p2##x,_n1##y,z,c), I[34] = (T)(img)(_p1##x,_n1##y,z,c), I[35] = (T)(img)(x,_n1##y,z,c), \
  I[36] = (T)(img)(_n1##x,_n1##y,z,c), I[37] = (T)(img)(_n2##x,_n1##y,z,c), I[38] = (T)(img)(_n3##x,_n1##y,z,c), \
  I[39] = (T)(img)(_n4##x,_n1##y,z,c), I[40] = (T)(img)(_p3##x,_n2##y,z,c), I[41] = (T)(img)(_p2##x,_n2##y,z,c), \
  I[42] = (T)(img)(_p1##x,_n2##y,z,c), I[43] = (T)(img)(x,_n2##y,z,c), I[44] = (T)(img)(_n1##x,_n2##y,z,c), \
  I[45] = (T)(img)(_n2##x,_n2##y,z,c), I[46] = (T)(img)(_n3##x,_n2##y,z,c), I[47] = (T)(img)(_n4##x,_n2##y,z,c), \
  I[48] = (T)(img)(_p3##x,_n3##y,z,c), I[49] = (T)(img)(_p2##x,_n3##y,z,c), I[50] = (T)(img)(_p1##x,_n3##y,z,c), \
  I[51] = (T)(img)(x,_n3##y,z,c), I[52] = (T)(img)(_n1##x,_n3##y,z,c), I[53] = (T)(img)(_n2##x,_n3##y,z,c), \
  I[54] = (T)(img)(_n3##x,_n3##y,z,c), I[55] = (T)(img)(_n4##x,_n3##y,z,c), I[56] = (T)(img)(_p3##x,_n4##y,z,c), \
  I[57] = (T)(img)(_p2##x,_n4##y,z,c), I[58] = (T)(img)(_p1##x,_n4##y,z,c), I[59] = (T)(img)(x,_n4##y,z,c), \
  I[60] = (T)(img)(_n1##x,_n4##y,z,c), I[61] = (T)(img)(_n2##x,_n4##y,z,c), I[62] = (T)(img)(_n3##x,_n4##y,z,c), \
  I[63] = (T)(img)(_n4##x,_n4##y,z,c);

#define cimg_get9x9(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p4##x,_p4##y,z,c), I[1] = (T)(img)(_p3##x,_p4##y,z,c), I[2] = (T)(img)(_p2##x,_p4##y,z,c), \
  I[3] = (T)(img)(_p1##x,_p4##y,z,c), I[4] = (T)(img)(x,_p4##y,z,c), I[5] = (T)(img)(_n1##x,_p4##y,z,c), \
  I[6] = (T)(img)(_n2##x,_p4##y,z,c), I[7] = (T)(img)(_n3##x,_p4##y,z,c), I[8] = (T)(img)(_n4##x,_p4##y,z,c), \
  I[9] = (T)(img)(_p4##x,_p3##y,z,c), I[10] = (T)(img)(_p3##x,_p3##y,z,c), I[11] = (T)(img)(_p2##x,_p3##y,z,c), \
  I[12] = (T)(img)(_p1##x,_p3##y,z,c), I[13] = (T)(img)(x,_p3##y,z,c), I[14] = (T)(img)(_n1##x,_p3##y,z,c), \
  I[15] = (T)(img)(_n2##x,_p3##y,z,c), I[16] = (T)(img)(_n3##x,_p3##y,z,c), I[17] = (T)(img)(_n4##x,_p3##y,z,c), \
  I[18] = (T)(img)(_p4##x,_p2##y,z,c), I[19] = (T)(img)(_p3##x,_p2##y,z,c), I[20] = (T)(img)(_p2##x,_p2##y,z,c), \
  I[21] = (T)(img)(_p1##x,_p2##y,z,c), I[22] = (T)(img)(x,_p2##y,z,c), I[23] = (T)(img)(_n1##x,_p2##y,z,c), \
  I[24] = (T)(img)(_n2##x,_p2##y,z,c), I[25] = (T)(img)(_n3##x,_p2##y,z,c), I[26] = (T)(img)(_n4##x,_p2##y,z,c), \
  I[27] = (T)(img)(_p4##x,_p1##y,z,c), I[28] = (T)(img)(_p3##x,_p1##y,z,c), I[29] = (T)(img)(_p2##x,_p1##y,z,c), \
  I[30] = (T)(img)(_p1##x,_p1##y,z,c), I[31] = (T)(img)(x,_p1##y,z,c), I[32] = (T)(img)(_n1##x,_p1##y,z,c), \
  I[33] = (T)(img)(_n2##x,_p1##y,z,c), I[34] = (T)(img)(_n3##x,_p1##y,z,c), I[35] = (T)(img)(_n4##x,_p1##y,z,c), \
  I[36] = (T)(img)(_p4##x,y,z,c), I[37] = (T)(img)(_p3##x,y,z,c), I[38] = (T)(img)(_p2##x,y,z,c), \
  I[39] = (T)(img)(_p1##x,y,z,c), I[40] = (T)(img)(x,y,z,c), I[41] = (T)(img)(_n1##x,y,z,c), \
  I[42] = (T)(img)(_n2##x,y,z,c), I[43] = (T)(img)(_n3##x,y,z,c), I[44] = (T)(img)(_n4##x,y,z,c), \
  I[45] = (T)(img)(_p4##x,_n1##y,z,c), I[46] = (T)(img)(_p3##x,_n1##y,z,c), I[47] = (T)(img)(_p2##x,_n1##y,z,c), \
  I[48] = (T)(img)(_p1##x,_n1##y,z,c), I[49] = (T)(img)(x,_n1##y,z,c), I[50] = (T)(img)(_n1##x,_n1##y,z,c), \
  I[51] = (T)(img)(_n2##x,_n1##y,z,c), I[52] = (T)(img)(_n3##x,_n1##y,z,c), I[53] = (T)(img)(_n4##x,_n1##y,z,c), \
  I[54] = (T)(img)(_p4##x,_n2##y,z,c), I[55] = (T)(img)(_p3##x,_n2##y,z,c), I[56] = (T)(img)(_p2##x,_n2##y,z,c), \
  I[57] = (T)(img)(_p1##x,_n2##y,z,c), I[58] = (T)(img)(x,_n2##y,z,c), I[59] = (T)(img)(_n1##x,_n2##y,z,c), \
  I[60] = (T)(img)(_n2##x,_n2##y,z,c), I[61] = (T)(img)(_n3##x,_n2##y,z,c), I[62] = (T)(img)(_n4##x,_n2##y,z,c), \
  I[63] = (T)(img)(_p4##x,_n3##y,z,c), I[64] = (T)(img)(_p3##x,_n3##y,z,c), I[65] = (T)(img)(_p2##x,_n3##y,z,c), \
  I[66] = (T)(img)(_p1##x,_n3##y,z,c), I[67] = (T)(img)(x,_n3##y,z,c), I[68] = (T)(img)(_n1##x,_n3##y,z,c), \
  I[69] = (T)(img)(_n2##x,_n3##y,z,c), I[70] = (T)(img)(_n3##x,_n3##y,z,c), I[71] = (T)(img)(_n4##x,_n3##y,z,c), \
  I[72] = (T)(img)(_p4##x,_n4##y,z,c), I[73] = (T)(img)(_p3##x,_n4##y,z,c), I[74] = (T)(img)(_p2##x,_n4##y,z,c), \
  I[75] = (T)(img)(_p1##x,_n4##y,z,c), I[76] = (T)(img)(x,_n4##y,z,c), I[77] = (T)(img)(_n1##x,_n4##y,z,c), \
  I[78] = (T)(img)(_n2##x,_n4##y,z,c), I[79] = (T)(img)(_n3##x,_n4##y,z,c), I[80] = (T)(img)(_n4##x,_n4##y,z,c)

#define cimg_get2x2x2(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(x,y,z,c), I[1] = (T)(img)(_n1##x,y,z,c), I[2] = (T)(img)(x,_n1##y,z,c), \
  I[3] = (T)(img)(_n1##x,_n1##y,z,c), I[4] = (T)(img)(x,y,_n1##z,c), I[5] = (T)(img)(_n1##x,y,_n1##z,c), \
  I[6] = (T)(img)(x,_n1##y,_n1##z,c), I[7] = (T)(img)(_n1##x,_n1##y,_n1##z,c)

#define cimg_get3x3x3(img,x,y,z,c,I,T) \
  I[0] = (T)(img)(_p1##x,_p1##y,_p1##z,c), I[1] = (T)(img)(x,_p1##y,_p1##z,c), \
  I[2] = (T)(img)(_n1##x,_p1##y,_p1##z,c), I[3] = (T)(img)(_p1##x,y,_p1##z,c), I[4] = (T)(img)(x,y,_p1##z,c), \
  I[5] = (T)(img)(_n1##x,y,_p1##z,c), I[6] = (T)(img)(_p1##x,_n1##y,_p1##z,c), I[7] = (T)(img)(x,_n1##y,_p1##z,c), \
  I[8] = (T)(img)(_n1##x,_n1##y,_p1##z,c), I[9] = (T)(img)(_p1##x,_p1##y,z,c), I[10] = (T)(img)(x,_p1##y,z,c), \
  I[11] = (T)(img)(_n1##x,_p1##y,z,c), I[12] = (T)(img)(_p1##x,y,z,c), I[13] = (T)(img)(x,y,z,c), \
  I[14] = (T)(img)(_n1##x,y,z,c), I[15] = (T)(img)(_p1##x,_n1##y,z,c), I[16] = (T)(img)(x,_n1##y,z,c), \
  I[17] = (T)(img)(_n1##x,_n1##y,z,c), I[18] = (T)(img)(_p1##x,_p1##y,_n1##z,c), I[19] = (T)(img)(x,_p1##y,_n1##z,c), \
  I[20] = (T)(img)(_n1##x,_p1##y,_n1##z,c), I[21] = (T)(img)(_p1##x,y,_n1##z,c), I[22] = (T)(img)(x,y,_n1##z,c), \
  I[23] = (T)(img)(_n1##x,y,_n1##z,c), I[24] = (T)(img)(_p1##x,_n1##y,_n1##z,c), I[25] = (T)(img)(x,_n1##y,_n1##z,c), \
  I[26] = (T)(img)(_n1##x,_n1##y,_n1##z,c)

// Macros to perform various image loops.
//
// These macros are simpler to use than loops with C++ iterators.
#define cimg_for(img,ptrs,T_ptrs) \
  for (T_ptrs *_max##ptrs = (img)._data + (img).size(), *ptrs = (img)._data; ptrs<_max##ptrs; ++ptrs)
#define cimg_rof(img,ptrs,T_ptrs) \
  for (T_ptrs *_min##ptrs = (img)?(img)._data:(T_ptrs*)0, \
         *ptrs = (img)?(img)._data + (img).size() - 1:(++_min##ptrs,(T_ptrs*)0); \
       ptrs>=_min##ptrs; --ptrs)
#define cimg_rof_openmp(img,ptrs,T_ptrs) \
  for (T_ptrs *ptrs = (img)._data + (img).size() - 1; ptrs>=(img)._data; --ptrs)
#define cimg_foroff(img,off) for (cimg_ulong off = 0, _max##off = (img).size(); off<_max##off; ++off)
#define cimg_rofoff(img,off) for (cimg_long off = (cimg_long)((img).size() - 1); off>=0; --off)

#define cimg_for1(bound,i) for (int i = 0; i<(int)(bound); ++i)
#define cimg_forX(img,x) cimg_for1((img)._width,x)
#define cimg_forY(img,y) cimg_for1((img)._height,y)
#define cimg_forZ(img,z) cimg_for1((img)._depth,z)
#define cimg_forC(img,c) cimg_for1((img)._spectrum,c)
#define cimg_forXY(img,x,y) cimg_forY(img,y) cimg_forX(img,x)
#define cimg_forXZ(img,x,z) cimg_forZ(img,z) cimg_forX(img,x)
#define cimg_forYZ(img,y,z) cimg_forZ(img,z) cimg_forY(img,y)
#define cimg_forXC(img,x,c) cimg_forC(img,c) cimg_forX(img,x)
#define cimg_forYC(img,y,c) cimg_forC(img,c) cimg_forY(img,y)
#define cimg_forZC(img,z,c) cimg_forC(img,c) cimg_forZ(img,z)
#define cimg_forXYZ(img,x,y,z) cimg_forZ(img,z) cimg_forXY(img,x,y)
#define cimg_forXYC(img,x,y,c) cimg_forC(img,c) cimg_forXY(img,x,y)
#define cimg_forXZC(img,x,z,c) cimg_forC(img,c) cimg_forXZ(img,x,z)
#define cimg_forYZC(img,y,z,c) cimg_forC(img,c) cimg_forYZ(img,y,z)
#define cimg_forXYZC(img,x,y,z,c) cimg_forC(img,c) cimg_forXYZ(img,x,y,z)

#define cimg_rof1(bound,i) for (int i = (int)(bound) - 1; i>=0; --i)
#define cimg_rofX(img,x) cimg_rof1((img)._width,x)
#define cimg_rofY(img,y) cimg_rof1((img)._height,y)
#define cimg_rofZ(img,z) cimg_rof1((img)._depth,z)
#define cimg_rofC(img,c) cimg_rof1((img)._spectrum,c)
#define cimg_rofXY(img,x,y) cimg_rofY(img,y) cimg_rofX(img,x)
#define cimg_rofXZ(img,x,z) cimg_rofZ(img,z) cimg_rofX(img,x)
#define cimg_rofYZ(img,y,z) cimg_rofZ(img,z) cimg_rofY(img,y)
#define cimg_rofXC(img,x,c) cimg_rofC(img,c) cimg_rofX(img,x)
#define cimg_rofYC(img,y,c) cimg_rofC(img,c) cimg_rofY(img,y)
#define cimg_rofZC(img,z,c) cimg_rofC(img,c) cimg_rofZ(img,z)
#define cimg_rofXYZ(img,x,y,z) cimg_rofZ(img,z) cimg_rofXY(img,x,y)
#define cimg_rofXYC(img,x,y,c) cimg_rofC(img,c) cimg_rofXY(img,x,y)
#define cimg_rofXZC(img,x,z,c) cimg_rofC(img,c) cimg_rofXZ(img,x,z)
#define cimg_rofYZC(img,y,z,c) cimg_rofC(img,c) cimg_rofYZ(img,y,z)
#define cimg_rofXYZC(img,x,y,z,c) cimg_rofC(img,c) cimg_rofXYZ(img,x,y,z)

#define cimg_for_in1(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), _max##i = (int)(i1)<(int)(bound)?(int)(i1):(int)(bound) - 1; i<=_max##i; ++i)
#define cimg_for_inX(img,x0,x1,x) cimg_for_in1((img)._width,x0,x1,x)
#define cimg_for_inY(img,y0,y1,y) cimg_for_in1((img)._height,y0,y1,y)
#define cimg_for_inZ(img,z0,z1,z) cimg_for_in1((img)._depth,z0,z1,z)
#define cimg_for_inC(img,c0,c1,c) cimg_for_in1((img)._spectrum,c0,c1,c)
#define cimg_for_inXY(img,x0,y0,x1,y1,x,y) cimg_for_inY(img,y0,y1,y) cimg_for_inX(img,x0,x1,x)
#define cimg_for_inXZ(img,x0,z0,x1,z1,x,z) cimg_for_inZ(img,z0,z1,z) cimg_for_inX(img,x0,x1,x)
#define cimg_for_inXC(img,x0,c0,x1,c1,x,c) cimg_for_inC(img,c0,c1,c) cimg_for_inX(img,x0,x1,x)
#define cimg_for_inYZ(img,y0,z0,y1,z1,y,z) cimg_for_inZ(img,x0,z1,z) cimg_for_inY(img,y0,y1,y)
#define cimg_for_inYC(img,y0,c0,y1,c1,y,c) cimg_for_inC(img,c0,c1,c) cimg_for_inY(img,y0,y1,y)
#define cimg_for_inZC(img,z0,c0,z1,c1,z,c) cimg_for_inC(img,c0,c1,c) cimg_for_inZ(img,z0,z1,z)
#define cimg_for_inXYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_inZ(img,z0,z1,z) cimg_for_inXY(img,x0,y0,x1,y1,x,y)
#define cimg_for_inXYC(img,x0,y0,c0,x1,y1,c1,x,y,c) cimg_for_inC(img,c0,c1,c) cimg_for_inXY(img,x0,y0,x1,y1,x,y)
#define cimg_for_inXZC(img,x0,z0,c0,x1,z1,c1,x,z,c) cimg_for_inC(img,c0,c1,c) cimg_for_inXZ(img,x0,z0,x1,z1,x,z)
#define cimg_for_inYZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_inC(img,c0,c1,c) cimg_for_inYZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_inXYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_inC(img,c0,c1,c) cimg_for_inXYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)
#define cimg_for_insideX(img,x,n) cimg_for_inX(img,n,(img)._width - 1 - (n),x)
#define cimg_for_insideY(img,y,n) cimg_for_inY(img,n,(img)._height - 1 - (n),y)
#define cimg_for_insideZ(img,z,n) cimg_for_inZ(img,n,(img)._depth  - 1 - (n),z)
#define cimg_for_insideC(img,c,n) cimg_for_inC(img,n,(img)._spectrum - 1 - (n),c)
#define cimg_for_insideXY(img,x,y,n) cimg_for_inXY(img,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n),x,y)
#define cimg_for_insideXYZ(img,x,y,z,n) \
  cimg_for_inXYZ(img,n,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n),(img)._depth - 1 - (n),x,y,z)
#define cimg_for_insideXYZC(img,x,y,z,c,n) \
  cimg_for_inXYZ(img,n,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n),(img)._depth - 1 - (n),x,y,z)

#define cimg_for_out1(boundi,i0,i1,i) \
 for (int i = (int)(i0)>0?0:(int)(i1) + 1; i<(int)(boundi); ++i, i = i==(int)(i0)?(int)(i1) + 1:i)
#define cimg_for_out2(boundi,boundj,i0,j0,i1,j1,i,j) \
 for (int j = 0; j<(int)(boundj); ++j) \
 for (int _n1j = (int)(j<(int)(j0) || j>(int)(j1)), i = _n1j?0:(int)(i0)>0?0:(int)(i1) + 1; i<(int)(boundi); \
  ++i, i = _n1j?i:(i==(int)(i0)?(int)(i1) + 1:i))
#define cimg_for_out3(boundi,boundj,boundk,i0,j0,k0,i1,j1,k1,i,j,k) \
 for (int k = 0; k<(int)(boundk); ++k) \
 for (int _n1k = (int)(k<(int)(k0) || k>(int)(k1)), j = 0; j<(int)(boundj); ++j) \
 for (int _n1j = (int)(j<(int)(j0) || j>(int)(j1)), i = _n1j || _n1k?0:(int)(i0)>0?0:(int)(i1) + 1; i<(int)(boundi); \
  ++i, i = _n1j || _n1k?i:(i==(int)(i0)?(int)(i1) + 1:i))
#define cimg_for_out4(boundi,boundj,boundk,boundl,i0,j0,k0,l0,i1,j1,k1,l1,i,j,k,l) \
 for (int l = 0; l<(int)(boundl); ++l) \
 for (int _n1l = (int)(l<(int)(l0) || l>(int)(l1)), k = 0; k<(int)(boundk); ++k) \
 for (int _n1k = (int)(k<(int)(k0) || k>(int)(k1)), j = 0; j<(int)(boundj); ++j) \
 for (int _n1j = (int)(j<(int)(j0) || j>(int)(j1)), i = _n1j || _n1k || _n1l?0:(int)(i0)>0?0:(int)(i1) + 1; \
  i<(int)(boundi); ++i, i = _n1j || _n1k || _n1l?i:(i==(int)(i0)?(int)(i1) + 1:i))
#define cimg_for_outX(img,x0,x1,x) cimg_for_out1((img)._width,x0,x1,x)
#define cimg_for_outY(img,y0,y1,y) cimg_for_out1((img)._height,y0,y1,y)
#define cimg_for_outZ(img,z0,z1,z) cimg_for_out1((img)._depth,z0,z1,z)
#define cimg_for_outC(img,c0,c1,c) cimg_for_out1((img)._spectrum,c0,c1,c)
#define cimg_for_outXY(img,x0,y0,x1,y1,x,y) cimg_for_out2((img)._width,(img)._height,x0,y0,x1,y1,x,y)
#define cimg_for_outXZ(img,x0,z0,x1,z1,x,z) cimg_for_out2((img)._width,(img)._depth,x0,z0,x1,z1,x,z)
#define cimg_for_outXC(img,x0,c0,x1,c1,x,c) cimg_for_out2((img)._width,(img)._spectrum,x0,c0,x1,c1,x,c)
#define cimg_for_outYZ(img,y0,z0,y1,z1,y,z) cimg_for_out2((img)._height,(img)._depth,y0,z0,y1,z1,y,z)
#define cimg_for_outYC(img,y0,c0,y1,c1,y,c) cimg_for_out2((img)._height,(img)._spectrum,y0,c0,y1,c1,y,c)
#define cimg_for_outZC(img,z0,c0,z1,c1,z,c) cimg_for_out2((img)._depth,(img)._spectrum,z0,c0,z1,c1,z,c)
#define cimg_for_outXYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) \
  cimg_for_out3((img)._width,(img)._height,(img)._depth,x0,y0,z0,x1,y1,z1,x,y,z)
#define cimg_for_outXYC(img,x0,y0,c0,x1,y1,c1,x,y,c) \
  cimg_for_out3((img)._width,(img)._height,(img)._spectrum,x0,y0,c0,x1,y1,c1,x,y,c)
#define cimg_for_outXZC(img,x0,z0,c0,x1,z1,c1,x,z,c) \
  cimg_for_out3((img)._width,(img)._depth,(img)._spectrum,x0,z0,c0,x1,z1,c1,x,z,c)
#define cimg_for_outYZC(img,y0,z0,c0,y1,z1,c1,y,z,c) \
  cimg_for_out3((img)._height,(img)._depth,(img)._spectrum,y0,z0,c0,y1,z1,c1,y,z,c)
#define cimg_for_outXYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
 cimg_for_out4((img)._width,(img)._height,(img)._depth,(img)._spectrum,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c)
#define cimg_for_borderX(img,x,n) cimg_for_outX(img,n,(img)._width - 1 - (n),x)
#define cimg_for_borderY(img,y,n) cimg_for_outY(img,n,(img)._height - 1 - (n),y)
#define cimg_for_borderZ(img,z,n) cimg_for_outZ(img,n,(img)._depth - 1 - (n),z)
#define cimg_for_borderC(img,c,n) cimg_for_outC(img,n,(img)._spectrum - 1 - (n),c)
#define cimg_for_borderXY(img,x,y,n) cimg_for_outXY(img,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n),x,y)
#define cimg_for_borderXYZ(img,x,y,z,n) \
  cimg_for_outXYZ(img,n,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n),(img)._depth - 1 - (n),x,y,z)
#define cimg_for_borderXYZC(img,x,y,z,c,n) \
 cimg_for_outXYZC(img,n,n,n,n,(img)._width - 1 - (n),(img)._height - 1 - (n), \
                  (img)._depth - 1 - (n),(img)._spectrum - 1 - (n),x,y,z,c)

#define cimg_for_spiralXY(img,x,y) \
 for (int x = 0, y = 0, _n1##x = 1, _n1##y = (img).width()*(img).height(); _n1##y; \
      --_n1##y, _n1##x+=(_n1##x>>2) - ((!(_n1##x&3)?--y:((_n1##x&3)==1?(img)._width - 1 - ++x:\
      ((_n1##x&3)==2?(img)._height - 1 - ++y:--x))))?0:1)

#define cimg_for_lineXY(x,y,x0,y0,x1,y1) \
 for (int x = (int)(x0), y = (int)(y0), _sx = 1, _sy = 1, _slope = 0, \
      _dx=(x1)>(x0)?(int)(x1) - (int)(x0):(_sx=-1,(int)(x0) - (int)(x1)), \
      _dy=(y1)>(y0)?(int)(y1) - (int)(y0):(_sy=-1,(int)(y0) - (int)(y1)), \
      _counter = _dx, \
      _err = _dx>_dy?(_dy>>1):((_slope=1),(_counter=_dy),(_dx>>1)); \
      _counter>=0; \
      --_counter, x+=_slope? \
      (y+=_sy,(_err-=_dx)<0?_err+=_dy,_sx:0): \
      (y+=(_err-=_dy)<0?_err+=_dx,_sy:0,_sx))

#define cimg_for2(bound,i) \
 for (int i = 0, _n1##i = 1>=(bound)?(int)(bound) - 1:1; \
      _n1##i<(int)(bound) || i==--_n1##i; \
      ++i, ++_n1##i)
#define cimg_for2X(img,x) cimg_for2((img)._width,x)
#define cimg_for2Y(img,y) cimg_for2((img)._height,y)
#define cimg_for2Z(img,z) cimg_for2((img)._depth,z)
#define cimg_for2C(img,c) cimg_for2((img)._spectrum,c)
#define cimg_for2XY(img,x,y) cimg_for2Y(img,y) cimg_for2X(img,x)
#define cimg_for2XZ(img,x,z) cimg_for2Z(img,z) cimg_for2X(img,x)
#define cimg_for2XC(img,x,c) cimg_for2C(img,c) cimg_for2X(img,x)
#define cimg_for2YZ(img,y,z) cimg_for2Z(img,z) cimg_for2Y(img,y)
#define cimg_for2YC(img,y,c) cimg_for2C(img,c) cimg_for2Y(img,y)
#define cimg_for2ZC(img,z,c) cimg_for2C(img,c) cimg_for2Z(img,z)
#define cimg_for2XYZ(img,x,y,z) cimg_for2Z(img,z) cimg_for2XY(img,x,y)
#define cimg_for2XZC(img,x,z,c) cimg_for2C(img,c) cimg_for2XZ(img,x,z)
#define cimg_for2YZC(img,y,z,c) cimg_for2C(img,c) cimg_for2YZ(img,y,z)
#define cimg_for2XYZC(img,x,y,z,c) cimg_for2C(img,c) cimg_for2XYZ(img,x,y,z)

#define cimg_for_in2(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1; \
      i<=(int)(i1) && (_n1##i<(int)(bound) || i==--_n1##i); \
      ++i, ++_n1##i)
#define cimg_for_in2X(img,x0,x1,x) cimg_for_in2((img)._width,x0,x1,x)
#define cimg_for_in2Y(img,y0,y1,y) cimg_for_in2((img)._height,y0,y1,y)
#define cimg_for_in2Z(img,z0,z1,z) cimg_for_in2((img)._depth,z0,z1,z)
#define cimg_for_in2C(img,c0,c1,c) cimg_for_in2((img)._spectrum,c0,c1,c)
#define cimg_for_in2XY(img,x0,y0,x1,y1,x,y) cimg_for_in2Y(img,y0,y1,y) cimg_for_in2X(img,x0,x1,x)
#define cimg_for_in2XZ(img,x0,z0,x1,z1,x,z) cimg_for_in2Z(img,z0,z1,z) cimg_for_in2X(img,x0,x1,x)
#define cimg_for_in2XC(img,x0,c0,x1,c1,x,c) cimg_for_in2C(img,c0,c1,c) cimg_for_in2X(img,x0,x1,x)
#define cimg_for_in2YZ(img,y0,z0,y1,z1,y,z) cimg_for_in2Z(img,z0,z1,z) cimg_for_in2Y(img,y0,y1,y)
#define cimg_for_in2YC(img,y0,c0,y1,c1,y,c) cimg_for_in2C(img,c0,c1,c) cimg_for_in2Y(img,y0,y1,y)
#define cimg_for_in2ZC(img,z0,c0,z1,c1,z,c) cimg_for_in2C(img,c0,c1,c) cimg_for_in2Z(img,z0,z1,z)
#define cimg_for_in2XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in2Z(img,z0,z1,z) cimg_for_in2XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in2XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in2C(img,c0,c1,c) cimg_for_in2XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in2YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in2C(img,c0,c1,c) cimg_for_in2YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in2XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in2C(img,c0,c1,c) cimg_for_in2XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for3(bound,i) \
 for (int i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1; \
      _n1##i<(int)(bound) || i==--_n1##i; \
      _p1##i = i++, ++_n1##i)
#define cimg_for3X(img,x) cimg_for3((img)._width,x)
#define cimg_for3Y(img,y) cimg_for3((img)._height,y)
#define cimg_for3Z(img,z) cimg_for3((img)._depth,z)
#define cimg_for3C(img,c) cimg_for3((img)._spectrum,c)
#define cimg_for3XY(img,x,y) cimg_for3Y(img,y) cimg_for3X(img,x)
#define cimg_for3XZ(img,x,z) cimg_for3Z(img,z) cimg_for3X(img,x)
#define cimg_for3XC(img,x,c) cimg_for3C(img,c) cimg_for3X(img,x)
#define cimg_for3YZ(img,y,z) cimg_for3Z(img,z) cimg_for3Y(img,y)
#define cimg_for3YC(img,y,c) cimg_for3C(img,c) cimg_for3Y(img,y)
#define cimg_for3ZC(img,z,c) cimg_for3C(img,c) cimg_for3Z(img,z)
#define cimg_for3XYZ(img,x,y,z) cimg_for3Z(img,z) cimg_for3XY(img,x,y)
#define cimg_for3XZC(img,x,z,c) cimg_for3C(img,c) cimg_for3XZ(img,x,z)
#define cimg_for3YZC(img,y,z,c) cimg_for3C(img,c) cimg_for3YZ(img,y,z)
#define cimg_for3XYZC(img,x,y,z,c) cimg_for3C(img,c) cimg_for3XYZ(img,x,y,z)

#define cimg_for_in3(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1; \
      i<=(int)(i1) && (_n1##i<(int)(bound) || i==--_n1##i); \
      _p1##i = i++, ++_n1##i)
#define cimg_for_in3X(img,x0,x1,x) cimg_for_in3((img)._width,x0,x1,x)
#define cimg_for_in3Y(img,y0,y1,y) cimg_for_in3((img)._height,y0,y1,y)
#define cimg_for_in3Z(img,z0,z1,z) cimg_for_in3((img)._depth,z0,z1,z)
#define cimg_for_in3C(img,c0,c1,c) cimg_for_in3((img)._spectrum,c0,c1,c)
#define cimg_for_in3XY(img,x0,y0,x1,y1,x,y) cimg_for_in3Y(img,y0,y1,y) cimg_for_in3X(img,x0,x1,x)
#define cimg_for_in3XZ(img,x0,z0,x1,z1,x,z) cimg_for_in3Z(img,z0,z1,z) cimg_for_in3X(img,x0,x1,x)
#define cimg_for_in3XC(img,x0,c0,x1,c1,x,c) cimg_for_in3C(img,c0,c1,c) cimg_for_in3X(img,x0,x1,x)
#define cimg_for_in3YZ(img,y0,z0,y1,z1,y,z) cimg_for_in3Z(img,z0,z1,z) cimg_for_in3Y(img,y0,y1,y)
#define cimg_for_in3YC(img,y0,c0,y1,c1,y,c) cimg_for_in3C(img,c0,c1,c) cimg_for_in3Y(img,y0,y1,y)
#define cimg_for_in3ZC(img,z0,c0,z1,c1,z,c) cimg_for_in3C(img,c0,c1,c) cimg_for_in3Z(img,z0,z1,z)
#define cimg_for_in3XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in3Z(img,z0,z1,z) cimg_for_in3XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in3XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in3C(img,c0,c1,c) cimg_for_in3XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in3YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in3C(img,c0,c1,c) cimg_for_in3YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in3XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in3C(img,c0,c1,c) cimg_for_in3XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for4(bound,i) \
 for (int i = 0, _p1##i = 0, _n1##i = 1>=(bound)?(int)(bound) - 1:1, \
      _n2##i = 2>=(bound)?(int)(bound) - 1:2; \
      _n2##i<(int)(bound) || _n1##i==--_n2##i || i==(_n2##i = --_n1##i); \
      _p1##i = i++, ++_n1##i, ++_n2##i)
#define cimg_for4X(img,x) cimg_for4((img)._width,x)
#define cimg_for4Y(img,y) cimg_for4((img)._height,y)
#define cimg_for4Z(img,z) cimg_for4((img)._depth,z)
#define cimg_for4C(img,c) cimg_for4((img)._spectrum,c)
#define cimg_for4XY(img,x,y) cimg_for4Y(img,y) cimg_for4X(img,x)
#define cimg_for4XZ(img,x,z) cimg_for4Z(img,z) cimg_for4X(img,x)
#define cimg_for4XC(img,x,c) cimg_for4C(img,c) cimg_for4X(img,x)
#define cimg_for4YZ(img,y,z) cimg_for4Z(img,z) cimg_for4Y(img,y)
#define cimg_for4YC(img,y,c) cimg_for4C(img,c) cimg_for4Y(img,y)
#define cimg_for4ZC(img,z,c) cimg_for4C(img,c) cimg_for4Z(img,z)
#define cimg_for4XYZ(img,x,y,z) cimg_for4Z(img,z) cimg_for4XY(img,x,y)
#define cimg_for4XZC(img,x,z,c) cimg_for4C(img,c) cimg_for4XZ(img,x,z)
#define cimg_for4YZC(img,y,z,c) cimg_for4C(img,c) cimg_for4YZ(img,y,z)
#define cimg_for4XYZC(img,x,y,z,c) cimg_for4C(img,c) cimg_for4XYZ(img,x,y,z)

#define cimg_for_in4(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
      _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2; \
      i<=(int)(i1) && (_n2##i<(int)(bound) || _n1##i==--_n2##i || i==(_n2##i = --_n1##i)); \
      _p1##i = i++, ++_n1##i, ++_n2##i)
#define cimg_for_in4X(img,x0,x1,x) cimg_for_in4((img)._width,x0,x1,x)
#define cimg_for_in4Y(img,y0,y1,y) cimg_for_in4((img)._height,y0,y1,y)
#define cimg_for_in4Z(img,z0,z1,z) cimg_for_in4((img)._depth,z0,z1,z)
#define cimg_for_in4C(img,c0,c1,c) cimg_for_in4((img)._spectrum,c0,c1,c)
#define cimg_for_in4XY(img,x0,y0,x1,y1,x,y) cimg_for_in4Y(img,y0,y1,y) cimg_for_in4X(img,x0,x1,x)
#define cimg_for_in4XZ(img,x0,z0,x1,z1,x,z) cimg_for_in4Z(img,z0,z1,z) cimg_for_in4X(img,x0,x1,x)
#define cimg_for_in4XC(img,x0,c0,x1,c1,x,c) cimg_for_in4C(img,c0,c1,c) cimg_for_in4X(img,x0,x1,x)
#define cimg_for_in4YZ(img,y0,z0,y1,z1,y,z) cimg_for_in4Z(img,z0,z1,z) cimg_for_in4Y(img,y0,y1,y)
#define cimg_for_in4YC(img,y0,c0,y1,c1,y,c) cimg_for_in4C(img,c0,c1,c) cimg_for_in4Y(img,y0,y1,y)
#define cimg_for_in4ZC(img,z0,c0,z1,c1,z,c) cimg_for_in4C(img,c0,c1,c) cimg_for_in4Z(img,z0,z1,z)
#define cimg_for_in4XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in4Z(img,z0,z1,z) cimg_for_in4XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in4XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in4C(img,c0,c1,c) cimg_for_in4XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in4YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in4C(img,c0,c1,c) cimg_for_in4YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in4XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in4C(img,c0,c1,c) cimg_for_in4XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for5(bound,i) \
 for (int i = 0, _p2##i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1, \
      _n2##i = 2>=(bound)?(int)(bound) - 1:2; \
      _n2##i<(int)(bound) || _n1##i==--_n2##i || i==(_n2##i = --_n1##i); \
      _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i)
#define cimg_for5X(img,x) cimg_for5((img)._width,x)
#define cimg_for5Y(img,y) cimg_for5((img)._height,y)
#define cimg_for5Z(img,z) cimg_for5((img)._depth,z)
#define cimg_for5C(img,c) cimg_for5((img)._spectrum,c)
#define cimg_for5XY(img,x,y) cimg_for5Y(img,y) cimg_for5X(img,x)
#define cimg_for5XZ(img,x,z) cimg_for5Z(img,z) cimg_for5X(img,x)
#define cimg_for5XC(img,x,c) cimg_for5C(img,c) cimg_for5X(img,x)
#define cimg_for5YZ(img,y,z) cimg_for5Z(img,z) cimg_for5Y(img,y)
#define cimg_for5YC(img,y,c) cimg_for5C(img,c) cimg_for5Y(img,y)
#define cimg_for5ZC(img,z,c) cimg_for5C(img,c) cimg_for5Z(img,z)
#define cimg_for5XYZ(img,x,y,z) cimg_for5Z(img,z) cimg_for5XY(img,x,y)
#define cimg_for5XZC(img,x,z,c) cimg_for5C(img,c) cimg_for5XZ(img,x,z)
#define cimg_for5YZC(img,y,z,c) cimg_for5C(img,c) cimg_for5YZ(img,y,z)
#define cimg_for5XYZC(img,x,y,z,c) cimg_for5C(img,c) cimg_for5XYZ(img,x,y,z)

#define cimg_for_in5(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p2##i = i - 2<0?0:i - 2, \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
      _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2; \
      i<=(int)(i1) && (_n2##i<(int)(bound) || _n1##i==--_n2##i || i==(_n2##i = --_n1##i)); \
      _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i)
#define cimg_for_in5X(img,x0,x1,x) cimg_for_in5((img)._width,x0,x1,x)
#define cimg_for_in5Y(img,y0,y1,y) cimg_for_in5((img)._height,y0,y1,y)
#define cimg_for_in5Z(img,z0,z1,z) cimg_for_in5((img)._depth,z0,z1,z)
#define cimg_for_in5C(img,c0,c1,c) cimg_for_in5((img)._spectrum,c0,c1,c)
#define cimg_for_in5XY(img,x0,y0,x1,y1,x,y) cimg_for_in5Y(img,y0,y1,y) cimg_for_in5X(img,x0,x1,x)
#define cimg_for_in5XZ(img,x0,z0,x1,z1,x,z) cimg_for_in5Z(img,z0,z1,z) cimg_for_in5X(img,x0,x1,x)
#define cimg_for_in5XC(img,x0,c0,x1,c1,x,c) cimg_for_in5C(img,c0,c1,c) cimg_for_in5X(img,x0,x1,x)
#define cimg_for_in5YZ(img,y0,z0,y1,z1,y,z) cimg_for_in5Z(img,z0,z1,z) cimg_for_in5Y(img,y0,y1,y)
#define cimg_for_in5YC(img,y0,c0,y1,c1,y,c) cimg_for_in5C(img,c0,c1,c) cimg_for_in5Y(img,y0,y1,y)
#define cimg_for_in5ZC(img,z0,c0,z1,c1,z,c) cimg_for_in5C(img,c0,c1,c) cimg_for_in5Z(img,z0,z1,z)
#define cimg_for_in5XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in5Z(img,z0,z1,z) cimg_for_in5XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in5XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in5C(img,c0,c1,c) cimg_for_in5XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in5YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in5C(img,c0,c1,c) cimg_for_in5YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in5XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in5C(img,c0,c1,c) cimg_for_in5XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for6(bound,i) \
 for (int i = 0, _p2##i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1, \
      _n2##i = 2>=(bound)?(int)(bound) - 1:2, \
      _n3##i = 3>=(bound)?(int)(bound) - 1:3; \
      _n3##i<(int)(bound) || _n2##i==--_n3##i || _n1##i==--_n2##i || i==(_n3##i = _n2##i = --_n1##i); \
      _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i)
#define cimg_for6X(img,x) cimg_for6((img)._width,x)
#define cimg_for6Y(img,y) cimg_for6((img)._height,y)
#define cimg_for6Z(img,z) cimg_for6((img)._depth,z)
#define cimg_for6C(img,c) cimg_for6((img)._spectrum,c)
#define cimg_for6XY(img,x,y) cimg_for6Y(img,y) cimg_for6X(img,x)
#define cimg_for6XZ(img,x,z) cimg_for6Z(img,z) cimg_for6X(img,x)
#define cimg_for6XC(img,x,c) cimg_for6C(img,c) cimg_for6X(img,x)
#define cimg_for6YZ(img,y,z) cimg_for6Z(img,z) cimg_for6Y(img,y)
#define cimg_for6YC(img,y,c) cimg_for6C(img,c) cimg_for6Y(img,y)
#define cimg_for6ZC(img,z,c) cimg_for6C(img,c) cimg_for6Z(img,z)
#define cimg_for6XYZ(img,x,y,z) cimg_for6Z(img,z) cimg_for6XY(img,x,y)
#define cimg_for6XZC(img,x,z,c) cimg_for6C(img,c) cimg_for6XZ(img,x,z)
#define cimg_for6YZC(img,y,z,c) cimg_for6C(img,c) cimg_for6YZ(img,y,z)
#define cimg_for6XYZC(img,x,y,z,c) cimg_for6C(img,c) cimg_for6XYZ(img,x,y,z)

#define cimg_for_in6(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p2##i = i - 2<0?0:i - 2, \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
      _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2, \
      _n3##i = i + 3>=(int)(bound)?(int)(bound) - 1:i + 3; \
      i<=(int)(i1) && \
      (_n3##i<(int)(bound) || _n2##i==--_n3##i || _n1##i==--_n2##i || i==(_n3##i = _n2##i = --_n1##i)); \
      _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i)
#define cimg_for_in6X(img,x0,x1,x) cimg_for_in6((img)._width,x0,x1,x)
#define cimg_for_in6Y(img,y0,y1,y) cimg_for_in6((img)._height,y0,y1,y)
#define cimg_for_in6Z(img,z0,z1,z) cimg_for_in6((img)._depth,z0,z1,z)
#define cimg_for_in6C(img,c0,c1,c) cimg_for_in6((img)._spectrum,c0,c1,c)
#define cimg_for_in6XY(img,x0,y0,x1,y1,x,y) cimg_for_in6Y(img,y0,y1,y) cimg_for_in6X(img,x0,x1,x)
#define cimg_for_in6XZ(img,x0,z0,x1,z1,x,z) cimg_for_in6Z(img,z0,z1,z) cimg_for_in6X(img,x0,x1,x)
#define cimg_for_in6XC(img,x0,c0,x1,c1,x,c) cimg_for_in6C(img,c0,c1,c) cimg_for_in6X(img,x0,x1,x)
#define cimg_for_in6YZ(img,y0,z0,y1,z1,y,z) cimg_for_in6Z(img,z0,z1,z) cimg_for_in6Y(img,y0,y1,y)
#define cimg_for_in6YC(img,y0,c0,y1,c1,y,c) cimg_for_in6C(img,c0,c1,c) cimg_for_in6Y(img,y0,y1,y)
#define cimg_for_in6ZC(img,z0,c0,z1,c1,z,c) cimg_for_in6C(img,c0,c1,c) cimg_for_in6Z(img,z0,z1,z)
#define cimg_for_in6XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in6Z(img,z0,z1,z) cimg_for_in6XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in6XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in6C(img,c0,c1,c) cimg_for_in6XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in6YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in6C(img,c0,c1,c) cimg_for_in6YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in6XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in6C(img,c0,c1,c) cimg_for_in6XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for7(bound,i) \
 for (int i = 0, _p3##i = 0, _p2##i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1, \
      _n2##i = 2>=(bound)?(int)(bound) - 1:2, \
      _n3##i = 3>=(bound)?(int)(bound) - 1:3; \
      _n3##i<(int)(bound) || _n2##i==--_n3##i || _n1##i==--_n2##i || i==(_n3##i = _n2##i = --_n1##i); \
      _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i)
#define cimg_for7X(img,x) cimg_for7((img)._width,x)
#define cimg_for7Y(img,y) cimg_for7((img)._height,y)
#define cimg_for7Z(img,z) cimg_for7((img)._depth,z)
#define cimg_for7C(img,c) cimg_for7((img)._spectrum,c)
#define cimg_for7XY(img,x,y) cimg_for7Y(img,y) cimg_for7X(img,x)
#define cimg_for7XZ(img,x,z) cimg_for7Z(img,z) cimg_for7X(img,x)
#define cimg_for7XC(img,x,c) cimg_for7C(img,c) cimg_for7X(img,x)
#define cimg_for7YZ(img,y,z) cimg_for7Z(img,z) cimg_for7Y(img,y)
#define cimg_for7YC(img,y,c) cimg_for7C(img,c) cimg_for7Y(img,y)
#define cimg_for7ZC(img,z,c) cimg_for7C(img,c) cimg_for7Z(img,z)
#define cimg_for7XYZ(img,x,y,z) cimg_for7Z(img,z) cimg_for7XY(img,x,y)
#define cimg_for7XZC(img,x,z,c) cimg_for7C(img,c) cimg_for7XZ(img,x,z)
#define cimg_for7YZC(img,y,z,c) cimg_for7C(img,c) cimg_for7YZ(img,y,z)
#define cimg_for7XYZC(img,x,y,z,c) cimg_for7C(img,c) cimg_for7XYZ(img,x,y,z)

#define cimg_for_in7(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p3##i = i - 3<0?0:i - 3, \
      _p2##i = i - 2<0?0:i - 2, \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
      _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2, \
      _n3##i = i + 3>=(int)(bound)?(int)(bound) - 1:i + 3; \
      i<=(int)(i1) && \
      (_n3##i<(int)(bound) || _n2##i==--_n3##i || _n1##i==--_n2##i || i==(_n3##i = _n2##i = --_n1##i)); \
      _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i)
#define cimg_for_in7X(img,x0,x1,x) cimg_for_in7((img)._width,x0,x1,x)
#define cimg_for_in7Y(img,y0,y1,y) cimg_for_in7((img)._height,y0,y1,y)
#define cimg_for_in7Z(img,z0,z1,z) cimg_for_in7((img)._depth,z0,z1,z)
#define cimg_for_in7C(img,c0,c1,c) cimg_for_in7((img)._spectrum,c0,c1,c)
#define cimg_for_in7XY(img,x0,y0,x1,y1,x,y) cimg_for_in7Y(img,y0,y1,y) cimg_for_in7X(img,x0,x1,x)
#define cimg_for_in7XZ(img,x0,z0,x1,z1,x,z) cimg_for_in7Z(img,z0,z1,z) cimg_for_in7X(img,x0,x1,x)
#define cimg_for_in7XC(img,x0,c0,x1,c1,x,c) cimg_for_in7C(img,c0,c1,c) cimg_for_in7X(img,x0,x1,x)
#define cimg_for_in7YZ(img,y0,z0,y1,z1,y,z) cimg_for_in7Z(img,z0,z1,z) cimg_for_in7Y(img,y0,y1,y)
#define cimg_for_in7YC(img,y0,c0,y1,c1,y,c) cimg_for_in7C(img,c0,c1,c) cimg_for_in7Y(img,y0,y1,y)
#define cimg_for_in7ZC(img,z0,c0,z1,c1,z,c) cimg_for_in7C(img,c0,c1,c) cimg_for_in7Z(img,z0,z1,z)
#define cimg_for_in7XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in7Z(img,z0,z1,z) cimg_for_in7XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in7XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in7C(img,c0,c1,c) cimg_for_in7XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in7YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in7C(img,c0,c1,c) cimg_for_in7YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in7XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in7C(img,c0,c1,c) cimg_for_in7XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for8(bound,i) \
 for (int i = 0, _p3##i = 0, _p2##i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1, \
      _n2##i = 2>=(bound)?(int)(bound) - 1:2, \
      _n3##i = 3>=(bound)?(int)(bound) - 1:3, \
      _n4##i = 4>=(bound)?(int)(bound) - 1:4; \
      _n4##i<(int)(bound) || _n3##i==--_n4##i || _n2##i==--_n3##i || _n1##i==--_n2##i || \
      i==(_n4##i = _n3##i = _n2##i = --_n1##i); \
      _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i, ++_n4##i)
#define cimg_for8X(img,x) cimg_for8((img)._width,x)
#define cimg_for8Y(img,y) cimg_for8((img)._height,y)
#define cimg_for8Z(img,z) cimg_for8((img)._depth,z)
#define cimg_for8C(img,c) cimg_for8((img)._spectrum,c)
#define cimg_for8XY(img,x,y) cimg_for8Y(img,y) cimg_for8X(img,x)
#define cimg_for8XZ(img,x,z) cimg_for8Z(img,z) cimg_for8X(img,x)
#define cimg_for8XC(img,x,c) cimg_for8C(img,c) cimg_for8X(img,x)
#define cimg_for8YZ(img,y,z) cimg_for8Z(img,z) cimg_for8Y(img,y)
#define cimg_for8YC(img,y,c) cimg_for8C(img,c) cimg_for8Y(img,y)
#define cimg_for8ZC(img,z,c) cimg_for8C(img,c) cimg_for8Z(img,z)
#define cimg_for8XYZ(img,x,y,z) cimg_for8Z(img,z) cimg_for8XY(img,x,y)
#define cimg_for8XZC(img,x,z,c) cimg_for8C(img,c) cimg_for8XZ(img,x,z)
#define cimg_for8YZC(img,y,z,c) cimg_for8C(img,c) cimg_for8YZ(img,y,z)
#define cimg_for8XYZC(img,x,y,z,c) cimg_for8C(img,c) cimg_for8XYZ(img,x,y,z)

#define cimg_for_in8(bound,i0,i1,i) \
 for (int i = (int)(i0)<0?0:(int)(i0), \
      _p3##i = i - 3<0?0:i - 3, \
      _p2##i = i - 2<0?0:i - 2, \
      _p1##i = i - 1<0?0:i - 1, \
      _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
      _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2, \
      _n3##i = i + 3>=(int)(bound)?(int)(bound) - 1:i + 3, \
      _n4##i = i + 4>=(int)(bound)?(int)(bound) - 1:i + 4; \
      i<=(int)(i1) && (_n4##i<(int)(bound) || _n3##i==--_n4##i || _n2##i==--_n3##i || _n1##i==--_n2##i || \
      i==(_n4##i = _n3##i = _n2##i = --_n1##i)); \
      _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i, ++_n4##i)
#define cimg_for_in8X(img,x0,x1,x) cimg_for_in8((img)._width,x0,x1,x)
#define cimg_for_in8Y(img,y0,y1,y) cimg_for_in8((img)._height,y0,y1,y)
#define cimg_for_in8Z(img,z0,z1,z) cimg_for_in8((img)._depth,z0,z1,z)
#define cimg_for_in8C(img,c0,c1,c) cimg_for_in8((img)._spectrum,c0,c1,c)
#define cimg_for_in8XY(img,x0,y0,x1,y1,x,y) cimg_for_in8Y(img,y0,y1,y) cimg_for_in8X(img,x0,x1,x)
#define cimg_for_in8XZ(img,x0,z0,x1,z1,x,z) cimg_for_in8Z(img,z0,z1,z) cimg_for_in8X(img,x0,x1,x)
#define cimg_for_in8XC(img,x0,c0,x1,c1,x,c) cimg_for_in8C(img,c0,c1,c) cimg_for_in8X(img,x0,x1,x)
#define cimg_for_in8YZ(img,y0,z0,y1,z1,y,z) cimg_for_in8Z(img,z0,z1,z) cimg_for_in8Y(img,y0,y1,y)
#define cimg_for_in8YC(img,y0,c0,y1,c1,y,c) cimg_for_in8C(img,c0,c1,c) cimg_for_in8Y(img,y0,y1,y)
#define cimg_for_in8ZC(img,z0,c0,z1,c1,z,c) cimg_for_in8C(img,c0,c1,c) cimg_for_in8Z(img,z0,z1,z)
#define cimg_for_in8XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in8Z(img,z0,z1,z) cimg_for_in8XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in8XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in8C(img,c0,c1,c) cimg_for_in8XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in8YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in8C(img,c0,c1,c) cimg_for_in8YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in8XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in8C(img,c0,c1,c) cimg_for_in8XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for9(bound,i) \
  for (int i = 0, _p4##i = 0, _p3##i = 0, _p2##i = 0, _p1##i = 0, \
       _n1##i = 1>=(int)(bound)?(int)(bound) - 1:1, \
       _n2##i = 2>=(int)(bound)?(int)(bound) - 1:2, \
       _n3##i = 3>=(int)(bound)?(int)(bound) - 1:3, \
       _n4##i = 4>=(int)(bound)?(int)(bound) - 1:4; \
       _n4##i<(int)(bound) || _n3##i==--_n4##i || _n2##i==--_n3##i || _n1##i==--_n2##i || \
       i==(_n4##i = _n3##i = _n2##i = --_n1##i); \
       _p4##i = _p3##i, _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i, ++_n4##i)
#define cimg_for9X(img,x) cimg_for9((img)._width,x)
#define cimg_for9Y(img,y) cimg_for9((img)._height,y)
#define cimg_for9Z(img,z) cimg_for9((img)._depth,z)
#define cimg_for9C(img,c) cimg_for9((img)._spectrum,c)
#define cimg_for9XY(img,x,y) cimg_for9Y(img,y) cimg_for9X(img,x)
#define cimg_for9XZ(img,x,z) cimg_for9Z(img,z) cimg_for9X(img,x)
#define cimg_for9XC(img,x,c) cimg_for9C(img,c) cimg_for9X(img,x)
#define cimg_for9YZ(img,y,z) cimg_for9Z(img,z) cimg_for9Y(img,y)
#define cimg_for9YC(img,y,c) cimg_for9C(img,c) cimg_for9Y(img,y)
#define cimg_for9ZC(img,z,c) cimg_for9C(img,c) cimg_for9Z(img,z)
#define cimg_for9XYZ(img,x,y,z) cimg_for9Z(img,z) cimg_for9XY(img,x,y)
#define cimg_for9XZC(img,x,z,c) cimg_for9C(img,c) cimg_for9XZ(img,x,z)
#define cimg_for9YZC(img,y,z,c) cimg_for9C(img,c) cimg_for9YZ(img,y,z)
#define cimg_for9XYZC(img,x,y,z,c) cimg_for9C(img,c) cimg_for9XYZ(img,x,y,z)

#define cimg_for_in9(bound,i0,i1,i) \
  for (int i = (int)(i0)<0?0:(int)(i0), \
       _p4##i = i - 4<0?0:i - 4, \
       _p3##i = i - 3<0?0:i - 3, \
       _p2##i = i - 2<0?0:i - 2, \
       _p1##i = i - 1<0?0:i - 1, \
       _n1##i = i + 1>=(int)(bound)?(int)(bound) - 1:i + 1, \
       _n2##i = i + 2>=(int)(bound)?(int)(bound) - 1:i + 2, \
       _n3##i = i + 3>=(int)(bound)?(int)(bound) - 1:i + 3, \
       _n4##i = i + 4>=(int)(bound)?(int)(bound) - 1:i + 4; \
       i<=(int)(i1) && (_n4##i<(int)(bound) || _n3##i==--_n4##i || _n2##i==--_n3##i || _n1##i==--_n2##i || \
       i==(_n4##i = _n3##i = _n2##i = --_n1##i)); \
       _p4##i = _p3##i, _p3##i = _p2##i, _p2##i = _p1##i, _p1##i = i++, ++_n1##i, ++_n2##i, ++_n3##i, ++_n4##i)
#define cimg_for_in9X(img,x0,x1,x) cimg_for_in9((img)._width,x0,x1,x)
#define cimg_for_in9Y(img,y0,y1,y) cimg_for_in9((img)._height,y0,y1,y)
#define cimg_for_in9Z(img,z0,z1,z) cimg_for_in9((img)._depth,z0,z1,z)
#define cimg_for_in9C(img,c0,c1,c) cimg_for_in9((img)._spectrum,c0,c1,c)
#define cimg_for_in9XY(img,x0,y0,x1,y1,x,y) cimg_for_in9Y(img,y0,y1,y) cimg_for_in9X(img,x0,x1,x)
#define cimg_for_in9XZ(img,x0,z0,x1,z1,x,z) cimg_for_in9Z(img,z0,z1,z) cimg_for_in9X(img,x0,x1,x)
#define cimg_for_in9XC(img,x0,c0,x1,c1,x,c) cimg_for_in9C(img,c0,c1,c) cimg_for_in9X(img,x0,x1,x)
#define cimg_for_in9YZ(img,y0,z0,y1,z1,y,z) cimg_for_in9Z(img,z0,z1,z) cimg_for_in9Y(img,y0,y1,y)
#define cimg_for_in9YC(img,y0,c0,y1,c1,y,c) cimg_for_in9C(img,c0,c1,c) cimg_for_in9Y(img,y0,y1,y)
#define cimg_for_in9ZC(img,z0,c0,z1,c1,z,c) cimg_for_in9C(img,c0,c1,c) cimg_for_in9Z(img,z0,z1,z)
#define cimg_for_in9XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z) cimg_for_in9Z(img,z0,z1,z) cimg_for_in9XY(img,x0,y0,x1,y1,x,y)
#define cimg_for_in9XZC(img,x0,z0,c0,x1,y1,c1,x,z,c) cimg_for_in9C(img,c0,c1,c) cimg_for_in9XZ(img,x0,y0,x1,y1,x,z)
#define cimg_for_in9YZC(img,y0,z0,c0,y1,z1,c1,y,z,c) cimg_for_in9C(img,c0,c1,c) cimg_for_in9YZ(img,y0,z0,y1,z1,y,z)
#define cimg_for_in9XYZC(img,x0,y0,z0,c0,x1,y1,z1,c1,x,y,z,c) \
  cimg_for_in9C(img,c0,c1,c) cimg_for_in9XYZ(img,x0,y0,z0,x1,y1,z1,x,y,z)

#define cimg_for2x2(img,x,y,z,c,I,T) \
  cimg_for2((img)._height,y) for (int x = 0, \
   _n1##x = (int)( \
   (I[0] = (T)(img)(0,y,z,c)), \
   (I[2] = (T)(img)(0,_n1##y,z,c)), \
   1>=(img)._width?(img).width() - 1:1);  \
   (_n1##x<(img).width() && ( \
   (I[1] = (T)(img)(_n1##x,y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x; \
   I[0] = I[1], \
   I[2] = I[3], \
   ++x, ++_n1##x)

#define cimg_for_in2x2(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in2((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _n1##x = (int)( \
   (I[0] = (T)(img)(x,y,z,c)), \
   (I[2] = (T)(img)(x,_n1##y,z,c)), \
   x + 1>=(int)(img)._width?(img).width() - 1:x + 1); \
   x<=(int)(x1) && ((_n1##x<(img).width() && (  \
   (I[1] = (T)(img)(_n1##x,y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x); \
   I[0] = I[1], \
   I[2] = I[3], \
   ++x, ++_n1##x)

#define cimg_for3x3(img,x,y,z,c,I,T) \
  cimg_for3((img)._height,y) for (int x = 0, \
   _p1##x = 0, \
   _n1##x = (int)( \
   (I[0] = I[1] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[3] = I[4] = (T)(img)(0,y,z,c)), \
   (I[6] = I[7] = (T)(img)(0,_n1##y,z,c)), \
   1>=(img)._width?(img).width() - 1:1); \
   (_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x; \
   I[0] = I[1], I[1] = I[2], \
   I[3] = I[4], I[4] = I[5], \
   I[6] = I[7], I[7] = I[8], \
   _p1##x = x++, ++_n1##x)

#define cimg_for_in3x3(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in3((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = (int)( \
   (I[0] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[3] = (T)(img)(_p1##x,y,z,c)), \
   (I[6] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[1] = (T)(img)(x,_p1##y,z,c)), \
   (I[4] = (T)(img)(x,y,z,c)), \
   (I[7] = (T)(img)(x,_n1##y,z,c)), \
   x + 1>=(int)(img)._width?(img).width() - 1:x + 1); \
   x<=(int)(x1) && ((_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x);            \
   I[0] = I[1], I[1] = I[2], \
   I[3] = I[4], I[4] = I[5], \
   I[6] = I[7], I[7] = I[8], \
   _p1##x = x++, ++_n1##x)

#define cimg_for4x4(img,x,y,z,c,I,T) \
  cimg_for4((img)._height,y) for (int x = 0, \
   _p1##x = 0, \
   _n1##x = 1>=(img)._width?(img).width() - 1:1, \
   _n2##x = (int)( \
   (I[0] = I[1] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[4] = I[5] = (T)(img)(0,y,z,c)), \
   (I[8] = I[9] = (T)(img)(0,_n1##y,z,c)), \
   (I[12] = I[13] = (T)(img)(0,_n2##y,z,c)), \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[6] = (T)(img)(_n1##x,y,z,c)), \
   (I[10] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,_n2##y,z,c)), \
   2>=(img)._width?(img).width() - 1:2); \
   (_n2##x<(img).width() && ( \
   (I[3] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[7] = (T)(img)(_n2##x,y,z,c)), \
   (I[11] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[15] = (T)(img)(_n2##x,_n2##y,z,c)),1)) || \
   _n1##x==--_n2##x || x==(_n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], \
   I[4] = I[5], I[5] = I[6], I[6] = I[7], \
   I[8] = I[9], I[9] = I[10], I[10] = I[11], \
   I[12] = I[13], I[13] = I[14], I[14] = I[15], \
   _p1##x = x++, ++_n1##x, ++_n2##x)

#define cimg_for_in4x4(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in4((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(int)(img)._width?(img).width() - 1:x + 1, \
   _n2##x = (int)( \
   (I[0] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[4] = (T)(img)(_p1##x,y,z,c)), \
   (I[8] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[12] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[1] = (T)(img)(x,_p1##y,z,c)), \
   (I[5] = (T)(img)(x,y,z,c)), \
   (I[9] = (T)(img)(x,_n1##y,z,c)), \
   (I[13] = (T)(img)(x,_n2##y,z,c)), \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[6] = (T)(img)(_n1##x,y,z,c)), \
   (I[10] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,_n2##y,z,c)), \
   x + 2>=(int)(img)._width?(img).width() - 1:x + 2); \
   x<=(int)(x1) && ((_n2##x<(img).width() && ( \
   (I[3] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[7] = (T)(img)(_n2##x,y,z,c)), \
   (I[11] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[15] = (T)(img)(_n2##x,_n2##y,z,c)),1)) || \
   _n1##x==--_n2##x || x==(_n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], \
   I[4] = I[5], I[5] = I[6], I[6] = I[7], \
   I[8] = I[9], I[9] = I[10], I[10] = I[11], \
   I[12] = I[13], I[13] = I[14], I[14] = I[15], \
   _p1##x = x++, ++_n1##x, ++_n2##x)

#define cimg_for5x5(img,x,y,z,c,I,T) \
 cimg_for5((img)._height,y) for (int x = 0, \
   _p2##x = 0, _p1##x = 0, \
   _n1##x = 1>=(img)._width?(img).width() - 1:1, \
   _n2##x = (int)( \
   (I[0] = I[1] = I[2] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[5] = I[6] = I[7] = (T)(img)(0,_p1##y,z,c)), \
   (I[10] = I[11] = I[12] = (T)(img)(0,y,z,c)), \
   (I[15] = I[16] = I[17] = (T)(img)(0,_n1##y,z,c)), \
   (I[20] = I[21] = I[22] = (T)(img)(0,_n2##y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[13] = (T)(img)(_n1##x,y,z,c)), \
   (I[18] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[23] = (T)(img)(_n1##x,_n2##y,z,c)),  \
   2>=(img)._width?(img).width() - 1:2); \
   (_n2##x<(img).width() && ( \
   (I[4] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[9] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[14] = (T)(img)(_n2##x,y,z,c)), \
   (I[19] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[24] = (T)(img)(_n2##x,_n2##y,z,c)),1)) || \
   _n1##x==--_n2##x || x==(_n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], \
   I[5] = I[6], I[6] = I[7], I[7] = I[8], I[8] = I[9], \
   I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], \
   I[15] = I[16], I[16] = I[17], I[17] = I[18], I[18] = I[19], \
   I[20] = I[21], I[21] = I[22], I[22] = I[23], I[23] = I[24], \
   _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x)

#define cimg_for_in5x5(img,x0,y0,x1,y1,x,y,z,c,I,T) \
 cimg_for_in5((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p2##x = x - 2<0?0:x - 2, \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(int)(img)._width?(img).width() - 1:x + 1, \
   _n2##x = (int)( \
   (I[0] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[5] = (T)(img)(_p2##x,_p1##y,z,c)), \
   (I[10] = (T)(img)(_p2##x,y,z,c)), \
   (I[15] = (T)(img)(_p2##x,_n1##y,z,c)), \
   (I[20] = (T)(img)(_p2##x,_n2##y,z,c)), \
   (I[1] = (T)(img)(_p1##x,_p2##y,z,c)), \
   (I[6] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[11] = (T)(img)(_p1##x,y,z,c)), \
   (I[16] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[21] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[2] = (T)(img)(x,_p2##y,z,c)), \
   (I[7] = (T)(img)(x,_p1##y,z,c)), \
   (I[12] = (T)(img)(x,y,z,c)), \
   (I[17] = (T)(img)(x,_n1##y,z,c)), \
   (I[22] = (T)(img)(x,_n2##y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[13] = (T)(img)(_n1##x,y,z,c)), \
   (I[18] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[23] = (T)(img)(_n1##x,_n2##y,z,c)), \
   x + 2>=(int)(img)._width?(img).width() - 1:x + 2); \
   x<=(int)(x1) && ((_n2##x<(img).width() && ( \
   (I[4] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[9] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[14] = (T)(img)(_n2##x,y,z,c)), \
   (I[19] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[24] = (T)(img)(_n2##x,_n2##y,z,c)),1)) || \
   _n1##x==--_n2##x || x==(_n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], \
   I[5] = I[6], I[6] = I[7], I[7] = I[8], I[8] = I[9], \
   I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], \
   I[15] = I[16], I[16] = I[17], I[17] = I[18], I[18] = I[19], \
   I[20] = I[21], I[21] = I[22], I[22] = I[23], I[23] = I[24], \
   _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x)

#define cimg_for6x6(img,x,y,z,c,I,T) \
 cimg_for6((img)._height,y) for (int x = 0, \
   _p2##x = 0, _p1##x = 0, \
   _n1##x = 1>=(img)._width?(img).width() - 1:1, \
   _n2##x = 2>=(img)._width?(img).width() - 1:2, \
   _n3##x = (int)( \
   (I[0] = I[1] = I[2] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[6] = I[7] = I[8] = (T)(img)(0,_p1##y,z,c)), \
   (I[12] = I[13] = I[14] = (T)(img)(0,y,z,c)), \
   (I[18] = I[19] = I[20] = (T)(img)(0,_n1##y,z,c)), \
   (I[24] = I[25] = I[26] = (T)(img)(0,_n2##y,z,c)), \
   (I[30] = I[31] = I[32] = (T)(img)(0,_n3##y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[9] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[15] = (T)(img)(_n1##x,y,z,c)), \
   (I[21] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[27] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[33] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[4] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[10] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[16] = (T)(img)(_n2##x,y,z,c)), \
   (I[22] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[28] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[34] = (T)(img)(_n2##x,_n3##y,z,c)), \
   3>=(img)._width?(img).width() - 1:3); \
   (_n3##x<(img).width() && ( \
   (I[5] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[11] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[17] = (T)(img)(_n3##x,y,z,c)), \
   (I[23] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[29] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[35] = (T)(img)(_n3##x,_n3##y,z,c)),1)) || \
   _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n3## x = _n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], \
   I[6] = I[7], I[7] = I[8], I[8] = I[9], I[9] = I[10], I[10] = I[11], \
   I[12] = I[13], I[13] = I[14], I[14] = I[15], I[15] = I[16], I[16] = I[17], \
   I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], \
   I[24] = I[25], I[25] = I[26], I[26] = I[27], I[27] = I[28], I[28] = I[29], \
   I[30] = I[31], I[31] = I[32], I[32] = I[33], I[33] = I[34], I[34] = I[35], \
   _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x)

#define cimg_for_in6x6(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in6((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)x0, \
   _p2##x = x - 2<0?0:x - 2, \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(int)(img)._width?(img).width() - 1:x + 1, \
   _n2##x = x + 2>=(int)(img)._width?(img).width() - 1:x + 2, \
   _n3##x = (int)( \
   (I[0] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[6] = (T)(img)(_p2##x,_p1##y,z,c)), \
   (I[12] = (T)(img)(_p2##x,y,z,c)), \
   (I[18] = (T)(img)(_p2##x,_n1##y,z,c)), \
   (I[24] = (T)(img)(_p2##x,_n2##y,z,c)), \
   (I[30] = (T)(img)(_p2##x,_n3##y,z,c)), \
   (I[1] = (T)(img)(_p1##x,_p2##y,z,c)), \
   (I[7] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[13] = (T)(img)(_p1##x,y,z,c)), \
   (I[19] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[25] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[31] = (T)(img)(_p1##x,_n3##y,z,c)), \
   (I[2] = (T)(img)(x,_p2##y,z,c)), \
   (I[8] = (T)(img)(x,_p1##y,z,c)), \
   (I[14] = (T)(img)(x,y,z,c)), \
   (I[20] = (T)(img)(x,_n1##y,z,c)), \
   (I[26] = (T)(img)(x,_n2##y,z,c)), \
   (I[32] = (T)(img)(x,_n3##y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[9] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[15] = (T)(img)(_n1##x,y,z,c)), \
   (I[21] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[27] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[33] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[4] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[10] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[16] = (T)(img)(_n2##x,y,z,c)), \
   (I[22] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[28] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[34] = (T)(img)(_n2##x,_n3##y,z,c)), \
   x + 3>=(int)(img)._width?(img).width() - 1:x + 3); \
   x<=(int)(x1) && ((_n3##x<(img).width() && ( \
   (I[5] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[11] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[17] = (T)(img)(_n3##x,y,z,c)), \
   (I[23] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[29] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[35] = (T)(img)(_n3##x,_n3##y,z,c)),1)) || \
   _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n3## x = _n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], \
   I[6] = I[7], I[7] = I[8], I[8] = I[9], I[9] = I[10], I[10] = I[11], \
   I[12] = I[13], I[13] = I[14], I[14] = I[15], I[15] = I[16], I[16] = I[17], \
   I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], \
   I[24] = I[25], I[25] = I[26], I[26] = I[27], I[27] = I[28], I[28] = I[29], \
   I[30] = I[31], I[31] = I[32], I[32] = I[33], I[33] = I[34], I[34] = I[35], \
   _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x)

#define cimg_for7x7(img,x,y,z,c,I,T) \
  cimg_for7((img)._height,y) for (int x = 0, \
   _p3##x = 0, _p2##x = 0, _p1##x = 0, \
   _n1##x = 1>=(img)._width?(img).width() - 1:1, \
   _n2##x = 2>=(img)._width?(img).width() - 1:2, \
   _n3##x = (int)( \
   (I[0] = I[1] = I[2] = I[3] = (T)(img)(_p3##x,_p3##y,z,c)), \
   (I[7] = I[8] = I[9] = I[10] = (T)(img)(0,_p2##y,z,c)), \
   (I[14] = I[15] = I[16] = I[17] = (T)(img)(0,_p1##y,z,c)), \
   (I[21] = I[22] = I[23] = I[24] = (T)(img)(0,y,z,c)), \
   (I[28] = I[29] = I[30] = I[31] = (T)(img)(0,_n1##y,z,c)), \
   (I[35] = I[36] = I[37] = I[38] = (T)(img)(0,_n2##y,z,c)), \
   (I[42] = I[43] = I[44] = I[45] = (T)(img)(0,_n3##y,z,c)), \
   (I[4] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[11] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[18] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[25] = (T)(img)(_n1##x,y,z,c)), \
   (I[32] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[39] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[46] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[5] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[12] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[19] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[26] = (T)(img)(_n2##x,y,z,c)), \
   (I[33] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[40] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[47] = (T)(img)(_n2##x,_n3##y,z,c)), \
   3>=(img)._width?(img).width() - 1:3); \
   (_n3##x<(img).width() && ( \
   (I[6] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[13] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[20] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[27] = (T)(img)(_n3##x,y,z,c)), \
   (I[34] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[41] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[48] = (T)(img)(_n3##x,_n3##y,z,c)),1)) || \
   _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n3##x = _n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], \
   I[7] = I[8], I[8] = I[9], I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], \
   I[14] = I[15], I[15] = I[16], I[16] = I[17], I[17] = I[18], I[18] = I[19], I[19] = I[20], \
   I[21] = I[22], I[22] = I[23], I[23] = I[24], I[24] = I[25], I[25] = I[26], I[26] = I[27], \
   I[28] = I[29], I[29] = I[30], I[30] = I[31], I[31] = I[32], I[32] = I[33], I[33] = I[34], \
   I[35] = I[36], I[36] = I[37], I[37] = I[38], I[38] = I[39], I[39] = I[40], I[40] = I[41], \
   I[42] = I[43], I[43] = I[44], I[44] = I[45], I[45] = I[46], I[46] = I[47], I[47] = I[48], \
   _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x)

#define cimg_for_in7x7(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in7((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p3##x = x - 3<0?0:x - 3, \
   _p2##x = x - 2<0?0:x - 2, \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(int)(img)._width?(img).width() - 1:x + 1, \
   _n2##x = x + 2>=(int)(img)._width?(img).width() - 1:x + 2, \
   _n3##x = (int)( \
   (I[0] = (T)(img)(_p3##x,_p3##y,z,c)), \
   (I[7] = (T)(img)(_p3##x,_p2##y,z,c)), \
   (I[14] = (T)(img)(_p3##x,_p1##y,z,c)), \
   (I[21] = (T)(img)(_p3##x,y,z,c)), \
   (I[28] = (T)(img)(_p3##x,_n1##y,z,c)), \
   (I[35] = (T)(img)(_p3##x,_n2##y,z,c)), \
   (I[42] = (T)(img)(_p3##x,_n3##y,z,c)), \
   (I[1] = (T)(img)(_p2##x,_p3##y,z,c)), \
   (I[8] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[15] = (T)(img)(_p2##x,_p1##y,z,c)), \
   (I[22] = (T)(img)(_p2##x,y,z,c)), \
   (I[29] = (T)(img)(_p2##x,_n1##y,z,c)), \
   (I[36] = (T)(img)(_p2##x,_n2##y,z,c)), \
   (I[43] = (T)(img)(_p2##x,_n3##y,z,c)), \
   (I[2] = (T)(img)(_p1##x,_p3##y,z,c)), \
   (I[9] = (T)(img)(_p1##x,_p2##y,z,c)), \
   (I[16] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[23] = (T)(img)(_p1##x,y,z,c)), \
   (I[30] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[37] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[44] = (T)(img)(_p1##x,_n3##y,z,c)), \
   (I[3] = (T)(img)(x,_p3##y,z,c)), \
   (I[10] = (T)(img)(x,_p2##y,z,c)), \
   (I[17] = (T)(img)(x,_p1##y,z,c)), \
   (I[24] = (T)(img)(x,y,z,c)), \
   (I[31] = (T)(img)(x,_n1##y,z,c)), \
   (I[38] = (T)(img)(x,_n2##y,z,c)), \
   (I[45] = (T)(img)(x,_n3##y,z,c)), \
   (I[4] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[11] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[18] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[25] = (T)(img)(_n1##x,y,z,c)), \
   (I[32] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[39] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[46] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[5] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[12] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[19] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[26] = (T)(img)(_n2##x,y,z,c)), \
   (I[33] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[40] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[47] = (T)(img)(_n2##x,_n3##y,z,c)), \
   x + 3>=(int)(img)._width?(img).width() - 1:x + 3); \
   x<=(int)(x1) && ((_n3##x<(img).width() && ( \
   (I[6] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[13] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[20] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[27] = (T)(img)(_n3##x,y,z,c)), \
   (I[34] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[41] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[48] = (T)(img)(_n3##x,_n3##y,z,c)),1)) || \
   _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n3##x = _n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], \
   I[7] = I[8], I[8] = I[9], I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], \
   I[14] = I[15], I[15] = I[16], I[16] = I[17], I[17] = I[18], I[18] = I[19], I[19] = I[20], \
   I[21] = I[22], I[22] = I[23], I[23] = I[24], I[24] = I[25], I[25] = I[26], I[26] = I[27], \
   I[28] = I[29], I[29] = I[30], I[30] = I[31], I[31] = I[32], I[32] = I[33], I[33] = I[34], \
   I[35] = I[36], I[36] = I[37], I[37] = I[38], I[38] = I[39], I[39] = I[40], I[40] = I[41], \
   I[42] = I[43], I[43] = I[44], I[44] = I[45], I[45] = I[46], I[46] = I[47], I[47] = I[48], \
   _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x)

#define cimg_for8x8(img,x,y,z,c,I,T) \
  cimg_for8((img)._height,y) for (int x = 0, \
   _p3##x = 0, _p2##x = 0, _p1##x = 0, \
   _n1##x = 1>=((img)._width)?(img).width() - 1:1, \
   _n2##x = 2>=((img)._width)?(img).width() - 1:2, \
   _n3##x = 3>=((img)._width)?(img).width() - 1:3, \
   _n4##x = (int)( \
   (I[0] = I[1] = I[2] = I[3] = (T)(img)(_p3##x,_p3##y,z,c)), \
   (I[8] = I[9] = I[10] = I[11] = (T)(img)(0,_p2##y,z,c)), \
   (I[16] = I[17] = I[18] = I[19] = (T)(img)(0,_p1##y,z,c)), \
   (I[24] = I[25] = I[26] = I[27] = (T)(img)(0,y,z,c)), \
   (I[32] = I[33] = I[34] = I[35] = (T)(img)(0,_n1##y,z,c)), \
   (I[40] = I[41] = I[42] = I[43] = (T)(img)(0,_n2##y,z,c)), \
   (I[48] = I[49] = I[50] = I[51] = (T)(img)(0,_n3##y,z,c)), \
   (I[56] = I[57] = I[58] = I[59] = (T)(img)(0,_n4##y,z,c)), \
   (I[4] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[12] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[20] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[28] = (T)(img)(_n1##x,y,z,c)), \
   (I[36] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[44] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[52] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[60] = (T)(img)(_n1##x,_n4##y,z,c)), \
   (I[5] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[13] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[21] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[29] = (T)(img)(_n2##x,y,z,c)), \
   (I[37] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[45] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[53] = (T)(img)(_n2##x,_n3##y,z,c)), \
   (I[61] = (T)(img)(_n2##x,_n4##y,z,c)), \
   (I[6] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[14] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[22] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[30] = (T)(img)(_n3##x,y,z,c)), \
   (I[38] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[46] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[54] = (T)(img)(_n3##x,_n3##y,z,c)), \
   (I[62] = (T)(img)(_n3##x,_n4##y,z,c)), \
   4>=((img)._width)?(img).width() - 1:4); \
   (_n4##x<(img).width() && ( \
   (I[7] = (T)(img)(_n4##x,_p3##y,z,c)), \
   (I[15] = (T)(img)(_n4##x,_p2##y,z,c)), \
   (I[23] = (T)(img)(_n4##x,_p1##y,z,c)), \
   (I[31] = (T)(img)(_n4##x,y,z,c)), \
   (I[39] = (T)(img)(_n4##x,_n1##y,z,c)), \
   (I[47] = (T)(img)(_n4##x,_n2##y,z,c)), \
   (I[55] = (T)(img)(_n4##x,_n3##y,z,c)), \
   (I[63] = (T)(img)(_n4##x,_n4##y,z,c)),1)) || \
   _n3##x==--_n4##x || _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n4##x = _n3##x = _n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], I[6] = I[7], \
   I[8] = I[9], I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], I[14] = I[15], \
   I[16] = I[17], I[17] = I[18], I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], \
   I[24] = I[25], I[25] = I[26], I[26] = I[27], I[27] = I[28], I[28] = I[29], I[29] = I[30], I[30] = I[31], \
   I[32] = I[33], I[33] = I[34], I[34] = I[35], I[35] = I[36], I[36] = I[37], I[37] = I[38], I[38] = I[39], \
   I[40] = I[41], I[41] = I[42], I[42] = I[43], I[43] = I[44], I[44] = I[45], I[45] = I[46], I[46] = I[47], \
   I[48] = I[49], I[49] = I[50], I[50] = I[51], I[51] = I[52], I[52] = I[53], I[53] = I[54], I[54] = I[55], \
   I[56] = I[57], I[57] = I[58], I[58] = I[59], I[59] = I[60], I[60] = I[61], I[61] = I[62], I[62] = I[63], \
   _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x, ++_n4##x)

#define cimg_for_in8x8(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in8((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p3##x = x - 3<0?0:x - 3, \
   _p2##x = x - 2<0?0:x - 2, \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(img).width()?(img).width() - 1:x + 1, \
   _n2##x = x + 2>=(img).width()?(img).width() - 1:x + 2, \
   _n3##x = x + 3>=(img).width()?(img).width() - 1:x + 3, \
   _n4##x = (int)( \
   (I[0] = (T)(img)(_p3##x,_p3##y,z,c)), \
   (I[8] = (T)(img)(_p3##x,_p2##y,z,c)), \
   (I[16] = (T)(img)(_p3##x,_p1##y,z,c)), \
   (I[24] = (T)(img)(_p3##x,y,z,c)), \
   (I[32] = (T)(img)(_p3##x,_n1##y,z,c)), \
   (I[40] = (T)(img)(_p3##x,_n2##y,z,c)), \
   (I[48] = (T)(img)(_p3##x,_n3##y,z,c)), \
   (I[56] = (T)(img)(_p3##x,_n4##y,z,c)), \
   (I[1] = (T)(img)(_p2##x,_p3##y,z,c)), \
   (I[9] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[17] = (T)(img)(_p2##x,_p1##y,z,c)), \
   (I[25] = (T)(img)(_p2##x,y,z,c)), \
   (I[33] = (T)(img)(_p2##x,_n1##y,z,c)), \
   (I[41] = (T)(img)(_p2##x,_n2##y,z,c)), \
   (I[49] = (T)(img)(_p2##x,_n3##y,z,c)), \
   (I[57] = (T)(img)(_p2##x,_n4##y,z,c)), \
   (I[2] = (T)(img)(_p1##x,_p3##y,z,c)), \
   (I[10] = (T)(img)(_p1##x,_p2##y,z,c)), \
   (I[18] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[26] = (T)(img)(_p1##x,y,z,c)), \
   (I[34] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[42] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[50] = (T)(img)(_p1##x,_n3##y,z,c)), \
   (I[58] = (T)(img)(_p1##x,_n4##y,z,c)), \
   (I[3] = (T)(img)(x,_p3##y,z,c)), \
   (I[11] = (T)(img)(x,_p2##y,z,c)), \
   (I[19] = (T)(img)(x,_p1##y,z,c)), \
   (I[27] = (T)(img)(x,y,z,c)), \
   (I[35] = (T)(img)(x,_n1##y,z,c)), \
   (I[43] = (T)(img)(x,_n2##y,z,c)), \
   (I[51] = (T)(img)(x,_n3##y,z,c)), \
   (I[59] = (T)(img)(x,_n4##y,z,c)), \
   (I[4] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[12] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[20] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[28] = (T)(img)(_n1##x,y,z,c)), \
   (I[36] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[44] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[52] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[60] = (T)(img)(_n1##x,_n4##y,z,c)), \
   (I[5] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[13] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[21] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[29] = (T)(img)(_n2##x,y,z,c)), \
   (I[37] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[45] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[53] = (T)(img)(_n2##x,_n3##y,z,c)), \
   (I[61] = (T)(img)(_n2##x,_n4##y,z,c)), \
   (I[6] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[14] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[22] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[30] = (T)(img)(_n3##x,y,z,c)), \
   (I[38] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[46] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[54] = (T)(img)(_n3##x,_n3##y,z,c)), \
   (I[62] = (T)(img)(_n3##x,_n4##y,z,c)), \
   x + 4>=(img).width()?(img).width() - 1:x + 4); \
   x<=(int)(x1) && ((_n4##x<(img).width() && ( \
   (I[7] = (T)(img)(_n4##x,_p3##y,z,c)), \
   (I[15] = (T)(img)(_n4##x,_p2##y,z,c)), \
   (I[23] = (T)(img)(_n4##x,_p1##y,z,c)), \
   (I[31] = (T)(img)(_n4##x,y,z,c)), \
   (I[39] = (T)(img)(_n4##x,_n1##y,z,c)), \
   (I[47] = (T)(img)(_n4##x,_n2##y,z,c)), \
   (I[55] = (T)(img)(_n4##x,_n3##y,z,c)), \
   (I[63] = (T)(img)(_n4##x,_n4##y,z,c)),1)) || \
   _n3##x==--_n4##x || _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n4##x = _n3##x = _n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], I[6] = I[7], \
   I[8] = I[9], I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], I[14] = I[15], \
   I[16] = I[17], I[17] = I[18], I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], \
   I[24] = I[25], I[25] = I[26], I[26] = I[27], I[27] = I[28], I[28] = I[29], I[29] = I[30], I[30] = I[31], \
   I[32] = I[33], I[33] = I[34], I[34] = I[35], I[35] = I[36], I[36] = I[37], I[37] = I[38], I[38] = I[39], \
   I[40] = I[41], I[41] = I[42], I[42] = I[43], I[43] = I[44], I[44] = I[45], I[45] = I[46], I[46] = I[47], \
   I[48] = I[49], I[49] = I[50], I[50] = I[51], I[51] = I[52], I[52] = I[53], I[53] = I[54], I[54] = I[55], \
   I[56] = I[57], I[57] = I[58], I[58] = I[59], I[59] = I[60], I[60] = I[61], I[61] = I[62], I[62] = I[63], \
   _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x, ++_n4##x)

#define cimg_for9x9(img,x,y,z,c,I,T) \
  cimg_for9((img)._height,y) for (int x = 0, \
   _p4##x = 0, _p3##x = 0, _p2##x = 0, _p1##x = 0, \
   _n1##x = 1>=((img)._width)?(img).width() - 1:1, \
   _n2##x = 2>=((img)._width)?(img).width() - 1:2, \
   _n3##x = 3>=((img)._width)?(img).width() - 1:3, \
   _n4##x = (int)( \
   (I[0] = I[1] = I[2] = I[3] = I[4] = (T)(img)(_p4##x,_p4##y,z,c)), \
   (I[9] = I[10] = I[11] = I[12] = I[13] = (T)(img)(0,_p3##y,z,c)), \
   (I[18] = I[19] = I[20] = I[21] = I[22] = (T)(img)(0,_p2##y,z,c)), \
   (I[27] = I[28] = I[29] = I[30] = I[31] = (T)(img)(0,_p1##y,z,c)), \
   (I[36] = I[37] = I[38] = I[39] = I[40] = (T)(img)(0,y,z,c)), \
   (I[45] = I[46] = I[47] = I[48] = I[49] = (T)(img)(0,_n1##y,z,c)), \
   (I[54] = I[55] = I[56] = I[57] = I[58] = (T)(img)(0,_n2##y,z,c)), \
   (I[63] = I[64] = I[65] = I[66] = I[67] = (T)(img)(0,_n3##y,z,c)), \
   (I[72] = I[73] = I[74] = I[75] = I[76] = (T)(img)(0,_n4##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,_p4##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[23] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[32] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[41] = (T)(img)(_n1##x,y,z,c)), \
   (I[50] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[59] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[68] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[77] = (T)(img)(_n1##x,_n4##y,z,c)), \
   (I[6] = (T)(img)(_n2##x,_p4##y,z,c)), \
   (I[15] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[24] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[33] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[42] = (T)(img)(_n2##x,y,z,c)), \
   (I[51] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[60] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[69] = (T)(img)(_n2##x,_n3##y,z,c)), \
   (I[78] = (T)(img)(_n2##x,_n4##y,z,c)), \
   (I[7] = (T)(img)(_n3##x,_p4##y,z,c)), \
   (I[16] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[25] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[34] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[43] = (T)(img)(_n3##x,y,z,c)), \
   (I[52] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[61] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[70] = (T)(img)(_n3##x,_n3##y,z,c)), \
   (I[79] = (T)(img)(_n3##x,_n4##y,z,c)), \
   4>=((img)._width)?(img).width() - 1:4); \
   (_n4##x<(img).width() && ( \
   (I[8] = (T)(img)(_n4##x,_p4##y,z,c)), \
   (I[17] = (T)(img)(_n4##x,_p3##y,z,c)), \
   (I[26] = (T)(img)(_n4##x,_p2##y,z,c)), \
   (I[35] = (T)(img)(_n4##x,_p1##y,z,c)), \
   (I[44] = (T)(img)(_n4##x,y,z,c)), \
   (I[53] = (T)(img)(_n4##x,_n1##y,z,c)), \
   (I[62] = (T)(img)(_n4##x,_n2##y,z,c)), \
   (I[71] = (T)(img)(_n4##x,_n3##y,z,c)), \
   (I[80] = (T)(img)(_n4##x,_n4##y,z,c)),1)) || \
   _n3##x==--_n4##x || _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n4##x = _n3##x = _n2##x = --_n1##x); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], I[6] = I[7], I[7] = I[8], \
   I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], I[14] = I[15], I[15] = I[16], \
   I[16] = I[17], I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], I[23] = I[24], \
   I[24] = I[25], I[25] = I[26], I[27] = I[28], I[28] = I[29], I[29] = I[30], I[30] = I[31], I[31] = I[32], \
   I[32] = I[33], I[33] = I[34], I[34] = I[35], I[36] = I[37], I[37] = I[38], I[38] = I[39], I[39] = I[40], \
   I[40] = I[41], I[41] = I[42], I[42] = I[43], I[43] = I[44], I[45] = I[46], I[46] = I[47], I[47] = I[48], \
   I[48] = I[49], I[49] = I[50], I[50] = I[51], I[51] = I[52], I[52] = I[53], I[54] = I[55], I[55] = I[56], \
   I[56] = I[57], I[57] = I[58], I[58] = I[59], I[59] = I[60], I[60] = I[61], I[61] = I[62], I[63] = I[64], \
   I[64] = I[65], I[65] = I[66], I[66] = I[67], I[67] = I[68], I[68] = I[69], I[69] = I[70], I[70] = I[71], \
   I[72] = I[73], I[73] = I[74], I[74] = I[75], I[75] = I[76], I[76] = I[77], I[77] = I[78], I[78] = I[79], \
   I[79] = I[80], \
   _p4##x = _p3##x, _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x, ++_n4##x)

#define cimg_for_in9x9(img,x0,y0,x1,y1,x,y,z,c,I,T) \
  cimg_for_in9((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p4##x = x - 4<0?0:x - 4, \
   _p3##x = x - 3<0?0:x - 3, \
   _p2##x = x - 2<0?0:x - 2, \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = x + 1>=(img).width()?(img).width() - 1:x + 1, \
   _n2##x = x + 2>=(img).width()?(img).width() - 1:x + 2, \
   _n3##x = x + 3>=(img).width()?(img).width() - 1:x + 3, \
   _n4##x = (int)( \
   (I[0] = (T)(img)(_p4##x,_p4##y,z,c)), \
   (I[9] = (T)(img)(_p4##x,_p3##y,z,c)), \
   (I[18] = (T)(img)(_p4##x,_p2##y,z,c)), \
   (I[27] = (T)(img)(_p4##x,_p1##y,z,c)), \
   (I[36] = (T)(img)(_p4##x,y,z,c)), \
   (I[45] = (T)(img)(_p4##x,_n1##y,z,c)), \
   (I[54] = (T)(img)(_p4##x,_n2##y,z,c)), \
   (I[63] = (T)(img)(_p4##x,_n3##y,z,c)), \
   (I[72] = (T)(img)(_p4##x,_n4##y,z,c)), \
   (I[1] = (T)(img)(_p3##x,_p4##y,z,c)), \
   (I[10] = (T)(img)(_p3##x,_p3##y,z,c)), \
   (I[19] = (T)(img)(_p3##x,_p2##y,z,c)), \
   (I[28] = (T)(img)(_p3##x,_p1##y,z,c)), \
   (I[37] = (T)(img)(_p3##x,y,z,c)), \
   (I[46] = (T)(img)(_p3##x,_n1##y,z,c)), \
   (I[55] = (T)(img)(_p3##x,_n2##y,z,c)), \
   (I[64] = (T)(img)(_p3##x,_n3##y,z,c)), \
   (I[73] = (T)(img)(_p3##x,_n4##y,z,c)), \
   (I[2] = (T)(img)(_p2##x,_p4##y,z,c)), \
   (I[11] = (T)(img)(_p2##x,_p3##y,z,c)), \
   (I[20] = (T)(img)(_p2##x,_p2##y,z,c)), \
   (I[29] = (T)(img)(_p2##x,_p1##y,z,c)), \
   (I[38] = (T)(img)(_p2##x,y,z,c)), \
   (I[47] = (T)(img)(_p2##x,_n1##y,z,c)), \
   (I[56] = (T)(img)(_p2##x,_n2##y,z,c)), \
   (I[65] = (T)(img)(_p2##x,_n3##y,z,c)), \
   (I[74] = (T)(img)(_p2##x,_n4##y,z,c)), \
   (I[3] = (T)(img)(_p1##x,_p4##y,z,c)), \
   (I[12] = (T)(img)(_p1##x,_p3##y,z,c)), \
   (I[21] = (T)(img)(_p1##x,_p2##y,z,c)), \
   (I[30] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[39] = (T)(img)(_p1##x,y,z,c)), \
   (I[48] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[57] = (T)(img)(_p1##x,_n2##y,z,c)), \
   (I[66] = (T)(img)(_p1##x,_n3##y,z,c)), \
   (I[75] = (T)(img)(_p1##x,_n4##y,z,c)), \
   (I[4] = (T)(img)(x,_p4##y,z,c)), \
   (I[13] = (T)(img)(x,_p3##y,z,c)), \
   (I[22] = (T)(img)(x,_p2##y,z,c)), \
   (I[31] = (T)(img)(x,_p1##y,z,c)), \
   (I[40] = (T)(img)(x,y,z,c)), \
   (I[49] = (T)(img)(x,_n1##y,z,c)), \
   (I[58] = (T)(img)(x,_n2##y,z,c)), \
   (I[67] = (T)(img)(x,_n3##y,z,c)), \
   (I[76] = (T)(img)(x,_n4##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,_p4##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,_p3##y,z,c)), \
   (I[23] = (T)(img)(_n1##x,_p2##y,z,c)), \
   (I[32] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[41] = (T)(img)(_n1##x,y,z,c)), \
   (I[50] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[59] = (T)(img)(_n1##x,_n2##y,z,c)), \
   (I[68] = (T)(img)(_n1##x,_n3##y,z,c)), \
   (I[77] = (T)(img)(_n1##x,_n4##y,z,c)), \
   (I[6] = (T)(img)(_n2##x,_p4##y,z,c)), \
   (I[15] = (T)(img)(_n2##x,_p3##y,z,c)), \
   (I[24] = (T)(img)(_n2##x,_p2##y,z,c)), \
   (I[33] = (T)(img)(_n2##x,_p1##y,z,c)), \
   (I[42] = (T)(img)(_n2##x,y,z,c)), \
   (I[51] = (T)(img)(_n2##x,_n1##y,z,c)), \
   (I[60] = (T)(img)(_n2##x,_n2##y,z,c)), \
   (I[69] = (T)(img)(_n2##x,_n3##y,z,c)), \
   (I[78] = (T)(img)(_n2##x,_n4##y,z,c)), \
   (I[7] = (T)(img)(_n3##x,_p4##y,z,c)), \
   (I[16] = (T)(img)(_n3##x,_p3##y,z,c)), \
   (I[25] = (T)(img)(_n3##x,_p2##y,z,c)), \
   (I[34] = (T)(img)(_n3##x,_p1##y,z,c)), \
   (I[43] = (T)(img)(_n3##x,y,z,c)), \
   (I[52] = (T)(img)(_n3##x,_n1##y,z,c)), \
   (I[61] = (T)(img)(_n3##x,_n2##y,z,c)), \
   (I[70] = (T)(img)(_n3##x,_n3##y,z,c)), \
   (I[79] = (T)(img)(_n3##x,_n4##y,z,c)), \
   x + 4>=(img).width()?(img).width() - 1:x + 4); \
   x<=(int)(x1) && ((_n4##x<(img).width() && ( \
   (I[8] = (T)(img)(_n4##x,_p4##y,z,c)), \
   (I[17] = (T)(img)(_n4##x,_p3##y,z,c)), \
   (I[26] = (T)(img)(_n4##x,_p2##y,z,c)), \
   (I[35] = (T)(img)(_n4##x,_p1##y,z,c)), \
   (I[44] = (T)(img)(_n4##x,y,z,c)), \
   (I[53] = (T)(img)(_n4##x,_n1##y,z,c)), \
   (I[62] = (T)(img)(_n4##x,_n2##y,z,c)), \
   (I[71] = (T)(img)(_n4##x,_n3##y,z,c)), \
   (I[80] = (T)(img)(_n4##x,_n4##y,z,c)),1)) || \
   _n3##x==--_n4##x || _n2##x==--_n3##x || _n1##x==--_n2##x || x==(_n4##x = _n3##x = _n2##x = --_n1##x)); \
   I[0] = I[1], I[1] = I[2], I[2] = I[3], I[3] = I[4], I[4] = I[5], I[5] = I[6], I[6] = I[7], I[7] = I[8], \
   I[9] = I[10], I[10] = I[11], I[11] = I[12], I[12] = I[13], I[13] = I[14], I[14] = I[15], I[15] = I[16], \
   I[16] = I[17], I[18] = I[19], I[19] = I[20], I[20] = I[21], I[21] = I[22], I[22] = I[23], I[23] = I[24], \
   I[24] = I[25], I[25] = I[26], I[27] = I[28], I[28] = I[29], I[29] = I[30], I[30] = I[31], I[31] = I[32], \
   I[32] = I[33], I[33] = I[34], I[34] = I[35], I[36] = I[37], I[37] = I[38], I[38] = I[39], I[39] = I[40], \
   I[40] = I[41], I[41] = I[42], I[42] = I[43], I[43] = I[44], I[45] = I[46], I[46] = I[47], I[47] = I[48], \
   I[48] = I[49], I[49] = I[50], I[50] = I[51], I[51] = I[52], I[52] = I[53], I[54] = I[55], I[55] = I[56], \
   I[56] = I[57], I[57] = I[58], I[58] = I[59], I[59] = I[60], I[60] = I[61], I[61] = I[62], I[63] = I[64], \
   I[64] = I[65], I[65] = I[66], I[66] = I[67], I[67] = I[68], I[68] = I[69], I[69] = I[70], I[70] = I[71], \
   I[72] = I[73], I[73] = I[74], I[74] = I[75], I[75] = I[76], I[76] = I[77], I[77] = I[78], I[78] = I[79], \
   I[79] = I[80], \
   _p4##x = _p3##x, _p3##x = _p2##x, _p2##x = _p1##x, _p1##x = x++, ++_n1##x, ++_n2##x, ++_n3##x, ++_n4##x)

#define cimg_for2x2x2(img,x,y,z,c,I,T) \
 cimg_for2((img)._depth,z) cimg_for2((img)._height,y) for (int x = 0, \
   _n1##x = (int)( \
   (I[0] = (T)(img)(0,y,z,c)), \
   (I[2] = (T)(img)(0,_n1##y,z,c)), \
   (I[4] = (T)(img)(0,y,_n1##z,c)), \
   (I[6] = (T)(img)(0,_n1##y,_n1##z,c)), \
   1>=(img)._width?(img).width() - 1:1); \
   (_n1##x<(img).width() && ( \
   (I[1] = (T)(img)(_n1##x,y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,_n1##z,c)), \
   (I[7] = (T)(img)(_n1##x,_n1##y,_n1##z,c)),1)) || \
   x==--_n1##x; \
   I[0] = I[1], I[2] = I[3], I[4] = I[5], I[6] = I[7], \
   ++x, ++_n1##x)

#define cimg_for_in2x2x2(img,x0,y0,z0,x1,y1,z1,x,y,z,c,I,T) \
 cimg_for_in2((img)._depth,z0,z1,z) cimg_for_in2((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _n1##x = (int)( \
   (I[0] = (T)(img)(x,y,z,c)), \
   (I[2] = (T)(img)(x,_n1##y,z,c)), \
   (I[4] = (T)(img)(x,y,_n1##z,c)), \
   (I[6] = (T)(img)(x,_n1##y,_n1##z,c)), \
   x + 1>=(int)(img)._width?(img).width() - 1:x + 1); \
   x<=(int)(x1) && ((_n1##x<(img).width() && ( \
   (I[1] = (T)(img)(_n1##x,y,z,c)), \
   (I[3] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,_n1##z,c)), \
   (I[7] = (T)(img)(_n1##x,_n1##y,_n1##z,c)),1)) || \
   x==--_n1##x); \
   I[0] = I[1], I[2] = I[3], I[4] = I[5], I[6] = I[7], \
   ++x, ++_n1##x)

#define cimg_for3x3x3(img,x,y,z,c,I,T) \
 cimg_for3((img)._depth,z) cimg_for3((img)._height,y) for (int x = 0, \
   _p1##x = 0, \
   _n1##x = (int)( \
   (I[0] = I[1] = (T)(img)(_p1##x,_p1##y,_p1##z,c)), \
   (I[3] = I[4] = (T)(img)(0,y,_p1##z,c)),  \
   (I[6] = I[7] = (T)(img)(0,_n1##y,_p1##z,c)), \
   (I[9] = I[10] = (T)(img)(0,_p1##y,z,c)), \
   (I[12] = I[13] = (T)(img)(0,y,z,c)), \
   (I[15] = I[16] = (T)(img)(0,_n1##y,z,c)), \
   (I[18] = I[19] = (T)(img)(0,_p1##y,_n1##z,c)), \
   (I[21] = I[22] = (T)(img)(0,y,_n1##z,c)), \
   (I[24] = I[25] = (T)(img)(0,_n1##y,_n1##z,c)), \
   1>=(img)._width?(img).width() - 1:1); \
   (_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,_p1##z,c)), \
   (I[5] = (T)(img)(_n1##x,y,_p1##z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,_p1##z,c)), \
   (I[11] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,y,z,c)), \
   (I[17] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[20] = (T)(img)(_n1##x,_p1##y,_n1##z,c)), \
   (I[23] = (T)(img)(_n1##x,y,_n1##z,c)), \
   (I[26] = (T)(img)(_n1##x,_n1##y,_n1##z,c)),1)) || \
   x==--_n1##x; \
   I[0] = I[1], I[1] = I[2], I[3] = I[4], I[4] = I[5], I[6] = I[7], I[7] = I[8], \
   I[9] = I[10], I[10] = I[11], I[12] = I[13], I[13] = I[14], I[15] = I[16], I[16] = I[17], \
   I[18] = I[19], I[19] = I[20], I[21] = I[22], I[22] = I[23], I[24] = I[25], I[25] = I[26], \
   _p1##x = x++, ++_n1##x)

#define cimg_for_in3x3x3(img,x0,y0,z0,x1,y1,z1,x,y,z,c,I,T) \
 cimg_for_in3((img)._depth,z0,z1,z) cimg_for_in3((img)._height,y0,y1,y) for (int x = (int)(x0)<0?0:(int)(x0), \
   _p1##x = x - 1<0?0:x - 1, \
   _n1##x = (int)( \
   (I[0] = (T)(img)(_p1##x,_p1##y,_p1##z,c)), \
   (I[3] = (T)(img)(_p1##x,y,_p1##z,c)),  \
   (I[6] = (T)(img)(_p1##x,_n1##y,_p1##z,c)), \
   (I[9] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[12] = (T)(img)(_p1##x,y,z,c)), \
   (I[15] = (T)(img)(_p1##x,_n1##y,z,c)), \
   (I[18] = (T)(img)(_p1##x,_p1##y,_n1##z,c)), \
   (I[21] = (T)(img)(_p1##x,y,_n1##z,c)), \
   (I[24] = (T)(img)(_p1##x,_n1##y,_n1##z,c)), \
   (I[1] = (T)(img)(x,_p1##y,_p1##z,c)), \
   (I[4] = (T)(img)(x,y,_p1##z,c)),  \
   (I[7] = (T)(img)(x,_n1##y,_p1##z,c)), \
   (I[10] = (T)(img)(x,_p1##y,z,c)), \
   (I[13] = (T)(img)(x,y,z,c)), \
   (I[16] = (T)(img)(x,_n1##y,z,c)), \
   (I[19] = (T)(img)(x,_p1##y,_n1##z,c)), \
   (I[22] = (T)(img)(x,y,_n1##z,c)), \
   (I[25] = (T)(img)(x,_n1##y,_n1##z,c)), \
   x + 1>=(int)(img)._width?(img).width() - 1:x + 1); \
   x<=(int)(x1) && ((_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,_p1##z,c)), \
   (I[5] = (T)(img)(_n1##x,y,_p1##z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,_p1##z,c)), \
   (I[11] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[14] = (T)(img)(_n1##x,y,z,c)), \
   (I[17] = (T)(img)(_n1##x,_n1##y,z,c)), \
   (I[20] = (T)(img)(_n1##x,_p1##y,_n1##z,c)), \
   (I[23] = (T)(img)(_n1##x,y,_n1##z,c)), \
   (I[26] = (T)(img)(_n1##x,_n1##y,_n1##z,c)),1)) || \
   x==--_n1##x); \
   I[0] = I[1], I[1] = I[2], I[3] = I[4], I[4] = I[5], I[6] = I[7], I[7] = I[8], \
   I[9] = I[10], I[10] = I[11], I[12] = I[13], I[13] = I[14], I[15] = I[16], I[16] = I[17], \
   I[18] = I[19], I[19] = I[20], I[21] = I[22], I[22] = I[23], I[24] = I[25], I[25] = I[26], \
   _p1##x = x++, ++_n1##x)

#define cimglist_for(list,l) for (int l = 0; l<(int)(list)._width; ++l)
#define cimglist_rof(list,l) for (int l = (int)(list)._width - 1; l>=0; --l)
#define cimglist_for_in(list,l0,l1,l) \
  for (int l = (int)(l0)<0?0:(int)(l0), _max##l = (unsigned int)l1<(list)._width?(int)(l1):(int)(list)._width - 1; \
  l<=_max##l; ++l)

#define cimglist_apply(list,fn) cimglist_for(list,__##fn) (list)[__##fn].fn

// Macros used to display error messages when exceptions are thrown.
// You should not use these macros is your own code.
#define _cimgdisplay_instance "[instance(%u,%u,%u,%c%s%c)] CImgDisplay::"
#define cimgdisplay_instance _width,_height,_normalization,_title?'\"':'[',_title?_title:"untitled",_title?'\"':']'
#define _cimg_instance "[instance(%u,%u,%u,%u,%p,%sshared)] CImg<%s>::"
#define cimg_instance _width,_height,_depth,_spectrum,_data,_is_shared?"":"non-",pixel_type()
#define _cimglist_instance "[instance(%u,%u,%p)] CImgList<%s>::"
#define cimglist_instance _width,_allocated_width,_data,pixel_type()

/*------------------------------------------------
 #
 #
 #  Define cimg_library:: namespace
 #
 #
 -------------------------------------------------*/
//! Contains <i>all classes and functions</i> of the \CImg library.
/**
   This namespace is defined to avoid function and class names collisions
   that should occur with the inclusion of other C++ header files.
   Regardless, collisions are rare, and you should typically start most of your
   \CImg-based programs with
   \code
   #include "CImg.h"
   using namespace cimg_library;
   \endcode
   to simplify the declaration of \CImg Library objects afterwards.
**/
namespace cimg_library {

  // Declare the four classes of the CImg Library.
  template<typename T=float> struct CImg;
  template<typename T=float> struct CImgList;
  struct CImgDisplay;
  struct CImgException;

  // Declare cimg:: namespace.
  // This is an incomplete namespace definition here. It only contains some stuff to ensure a correct declaration order
  // of the classes and functions defined afterwards.
  namespace cimg {

    // Define character sequences for colored terminal output.
#ifdef cimg_use_vt100
    inline const char* t_normal() { return "\x1b[0;0;0m"; }
    inline const char* t_black() { return "\x1b[0;30;59m"; }
    inline const char* t_red() { return "\x1b[0;31;59m"; }
    inline const char* t_green() { return "\x1b[0;32;59m"; }
    inline const char* t_yellow() { return "\x1b[0;33;59m"; }
    inline const char* t_blue() { return "\x1b[0;34;59m"; }
    inline const char* t_magenta() { return "\x1b[0;35;59m"; }
    inline const char* t_cyan() { return "\x1b[0;36;59m"; }
    inline const char* t_white() { return "\x1b[0;37;59m"; }
    inline const char *t_bold() { return "\x1b[1m"; }
    inline const char *t_underscore() { return "\x1b[4m"; }
#else
    inline const char* t_normal() { return ""; };
    inline const char* t_black() { return t_normal(); }
    inline const char* t_red() { return t_normal(); }
    inline const char* t_green() { return t_normal(); }
    inline const char* t_yellow() { return t_normal(); }
    inline const char* t_blue() { return t_normal(); }
    inline const char* t_magenta() { return t_normal(); }
    inline const char* t_cyan() { return t_normal(); }
    inline const char* t_white() { return t_normal(); }
    inline const char* t_bold() { return t_normal(); }
    inline const char* t_underscore() { return t_normal(); }
#endif

    inline std::FILE* output(std::FILE *file=0);
    inline void info();

    //! Avoid warning messages due to unused parameters. This function intentionally does nothing.
    template<typename T>
    inline void unused(const T&) {}

    template<typename T1,typename T2>
    inline void unused(const T1&, const T2&) {}

    template<typename T1,typename T2, typename T3>
    inline void unused(const T1&, const T2&, const T3&) {}

    template<typename T1,typename T2, typename T3, typename T4>
    inline void unused(const T1&, const T2&, const T3&, const T4&) {}

    template<typename T1,typename T2, typename T3, typename T4, typename T5>
    inline void unused(const T1&, const T2&, const T3&, const T4&, const T5&) {}

    template<typename T1,typename T2, typename T3, typename T4, typename T5, typename T6>
    inline void unused(const T1&, const T2&, const T3&, const T4&, const T5&, const T6&) {}

    // [internal] Lock/unlock a mutex for managing concurrent threads.
    // 'lock_mode' can be { 0=unlock | 1=lock | 2=trylock }.
    // 'n' can be in [0,31] but mutex range [0,15] is reserved by CImg.
    inline int mutex(const unsigned int n, const int lock_mode=1);

    inline unsigned int& exception_mode(const unsigned int mode, const bool is_set) {
      static unsigned int value = cimg_verbosity;
      if (is_set) { cimg::mutex(0); value = mode<4?mode:4; cimg::mutex(0,0); }
      return value;
    }

    //! Set current \CImg exception mode.
    /**
       The way error messages are handled by \CImg can be changed dynamically, using this function.
       \param mode Desired exception mode. Possible values are:
       - \c 0: Hide library messages (quiet mode).
       - \c 1: Print library messages on the console.
       - \c 2: Display library messages on a dialog window.
       - \c 3: Do as \c 1 + add extra debug warnings (slow down the code!).
       - \c 4: Do as \c 2 + add extra debug warnings (slow down the code!).
     **/
    inline unsigned int& exception_mode(const unsigned int mode) {
      return exception_mode(mode,true);
    }

    //! Return current \CImg exception mode.
    /**
       \note By default, return the value of configuration macro \c cimg_verbosity
    **/
    inline unsigned int& exception_mode() {
      return exception_mode(0,false);
    }

    inline unsigned int openmp_mode(const unsigned int mode, const bool is_set) {
#if cimg_use_openmp!=0
      static unsigned int value = 2;
      if (is_set)  { cimg::mutex(0); value = mode<2?mode:2; cimg::mutex(0,0); }
      return value;
#else
      cimg::unused(mode,is_set);
      return 0;
#endif
    }

    //! Set current \CImg openmp mode.
    /**
       The way openmp-based functions are handled by \CImg can be changed dynamically, using this function.
       \param mode Desired openmp mode. Possible values are:
       - \c 0: Never parallelize.
       - \c 1: Always parallelize.
       - \c 2: Adaptive parallelization mode (default behavior).
     **/
    inline unsigned int openmp_mode(const unsigned int mode) {
      return openmp_mode(mode,true);
    }

    //! Return current \CImg openmp mode.
    inline unsigned int openmp_mode() {
      return openmp_mode(0,false);
    }

    // Get or set load from network mode (can be { 0=disabled | 1=enabled }).
    inline bool& network_mode(const bool mode, const bool is_set) {
      static bool value = true;
      if (is_set) { cimg::mutex(0); value = mode; cimg::mutex(0,0); }
      return value;
    }

    inline bool& network_mode(const bool mode) {
      return network_mode(mode,true);
    }

    inline bool& network_mode() {
      return network_mode(false,false);
    }

    // Set/Get a global user_agent value.
    inline const char* user_agent(const char *const str=0) {
      static const char *value = "CImg";
      if (str) { cimg::mutex(0); value = str; cimg::mutex(0,0); }
      return value;
    }

    // Functions to return standard streams 'stdin', 'stdout' and 'stderr'.
    inline FILE* _stdin(const bool throw_exception=true);
    inline FILE* _stdout(const bool throw_exception=true);
    inline FILE* _stderr(const bool throw_exception=true);

    // Mandatory because Microsoft's _snprintf() and _vsnprintf() do not add the '\0' character
    // at the end of the string.
#if cimg_OS==2 && defined(_MSC_VER)
    inline int _snprintf(char *const s, const size_t size, const char *const format, ...) {
      va_list ap;
      va_start(ap,format);
      const int result = _vsnprintf(s,size,format,ap);
      va_end(ap);
      return result;
    }

    inline int _vsnprintf(char *const s, const size_t size, const char *const format, va_list ap) {
      int result = -1;
      cimg::mutex(6);
      if (size) result = _vsnprintf_s(s,size,_TRUNCATE,format,ap);
      if (result==-1) result = _vscprintf(format,ap);
      cimg::mutex(6,0);
      return result;
    }

    // Mutex-protected version of sscanf, snprintf and vnsprintf.
    // Used only MacOSX, as it seems those functions are not re-entrant on MacOSX.
#elif defined(__MACOSX__) || defined(__APPLE__)
    inline int _sscanf(const char *const s, const char *const format, ...) {
      cimg::mutex(6);
      va_list args;
      va_start(args,format);
      const int result = std::vsscanf(s,format,args);
      va_end(args);
      cimg::mutex(6,0);
      return result;
    }

    inline int _snprintf(char *const s, const size_t n, const char *const format, ...) {
      cimg::mutex(6);
      va_list args;
      va_start(args,format);
      const int result = std::vsnprintf(s,n,format,args);
      va_end(args);
      cimg::mutex(6,0);
      return result;
    }

    inline int _vsnprintf(char *const s, const size_t size, const char* format, va_list ap) {
      cimg::mutex(6);
      const int result = std::vsnprintf(s,size,format,ap);
      cimg::mutex(6,0);
      return result;
    }
#endif

#ifndef cimg_openmp_sizefactor
#define cimg_openmp_sizefactor 1
#endif
#define cimg_openmp_if(cond) if ((cimg::openmp_mode()==1 || (cimg::openmp_mode()>1 && (cond))))
#define cimg_openmp_if_size(size,min_size) cimg_openmp_if((size)>=(cimg_openmp_sizefactor)*(min_size))
#ifdef _MSC_VER
// Disable 'collapse()' directive for MSVC (supports only OpenMP 2.0).
#define cimg_openmp_collapse(k)
#else
#define cimg_openmp_collapse(k) collapse(k)
#endif

#if cimg_OS==2
// Disable parallelization of simple loops on Windows, due to noticed performance drop.
#define cimg_openmp_for(instance,expr,min_size,T) cimg_rof((instance),ptr,T) *ptr = (T)(expr);
#else
#define cimg_openmp_for(instance,expr,min_size,T) \
    cimg_pragma_openmp(parallel for cimg_openmp_if_size((instance).size(),min_size)) \
    cimg_rof_openmp(instance,ptr,T) *ptr = (T)(expr);
#endif

    // Display a simple dialog box, and wait for the user's response.
    inline int dialog(const char *const title, const char *const msg,
                      const char *const button1_label="OK", const char *const button2_label=0,
                      const char *const button3_label=0, const char *const button4_label=0,
                      const char *const button5_label=0, const char *const button6_label=0,
                      const bool centering=false);

    // Evaluate math expression.
    inline double eval(const char *const expression,
                       const double x=0, const double y=0, const double z=0, const double c=0);

    // Create a directory.
    inline void create_directory(const char *const dirname, const bool force_overwrite=true);

  } // namespace cimg { ...

  /*---------------------------------------
    #
    # Define the CImgException structures
    #
    --------------------------------------*/
  //! Instances of \c CImgException are thrown when errors are encountered in a \CImg function call.
  /**
     \par Overview

      CImgException is the base class of all exceptions thrown by \CImg (except \b CImgAbortException).
      CImgException is never thrown directly. Derived classes that specify the type of error are thrown instead.
      These classes can be:

      - \b CImgAbortException: Thrown when a computationally-intensive function is aborted by an external signal.
        This is the only \c non-derived exception class.

      - \b CImgArgumentException: Thrown when one argument of a called \CImg function is invalid.
      This is probably one of the most commonly thrown exceptions in \CImg.
      For instance, the following example throws a \c CImgArgumentException:
      \code
      CImg<float> img(100,100,1,3); // Define a 100x100 color image with float-valued pixels
      img.mirror('e'); // Try to mirror image along the (non-existing) 'e'-axis
      \endcode

      - \b CImgDisplayException: Thrown when something went wrong during the display of images in CImgDisplay instances.

      - \b CImgInstanceException: Thrown when an instance associated with a called \CImg function does not meet
      the function's requirements. For instance, the following example throws a \c CImgInstanceException:
      \code
      const CImg<float> img; // Define an empty image
      const float value = img.at(0); // Try to read first pixel value (does not exist)
      \endcode

      - \b CImgIOException: Thrown when an error occurred when trying to load or save image files.
      This happens when trying to read files that do not exist or with invalid formats.
      For instance, the following example throws a \c CImgIOException:
      \code
      const CImg<float> img("missing_file.jpg"); // Try to load a file that does not exist
      \endcode

      - \b CImgWarningException: Thrown only if configuration macro \c cimg_strict_warnings is set, and
      when a \CImg function has to display a warning message (see cimg::warn()).

      It is not recommended to throw CImgException instances manually, as they are intended to be thrown only
      by the \CImg library.
      When an error occurs in a library function call, \CImg may display error messages on the screen or on the
      standard output, depending on the current \CImg exception mode.
      The \CImg exception mode can be queried and set by functions cimg::exception_mode() and
      cimg::exception_mode(unsigned int).

      \par Exceptions handling

      In all cases, when an error occurs in \CImg, an instance of the corresponding exception class is thrown.
      This may lead the program to break (this is the default behavior), but you can bypass this behavior by
      handling the exceptions by yourself,
      using a usual <tt>try { ... } catch () { ... }</tt> block, as in the following example:
      \code
      #include "CImg.h"
      using namespace cimg_library;
      int main() {
        cimg::exception_mode(0); // Enable quiet exception mode
        try {
          ... // Here, do what you want to stress CImg
        } catch (CImgException& e) { // You succeeded: something went wrong!
          std::fprintf(stderr,"CImg Library Error: %s",e.what()); // Display your custom error message
          ... // Perform necessary recovery or cleanup steps here
          }
        }
      \endcode
  **/
  struct CImgException : public std::exception {
#define _cimg_exception_err(etype,disp_flag) \
  std::va_list ap, ap2; \
  va_start(ap,format); va_start(ap2,format); \
  int size = cimg_vsnprintf(0,0,format,ap2); \
  if (size++>=0) { \
    delete[] _message; \
    _message = new char[(size_t)size]; \
    cimg_vsnprintf(_message,(size_t)size,format,ap); \
    if (cimg::exception_mode()) { \
      std::fprintf(cimg::output(),"\n%s[CImg] *** %s ***%s %s\n",cimg::t_red(),etype,cimg::t_normal(),_message); \
      if (cimg_display && disp_flag && !(cimg::exception_mode()%2)) try { cimg::dialog(etype,_message,"Abort"); } \
      catch (CImgException&) {} \
      if (cimg::exception_mode()>=3) cimg_library::cimg::info(); \
    } \
  } \
  va_end(ap); va_end(ap2);

    char *_message;
    CImgException() { _message = new char[1]; *_message = 0; }
    CImgException(const char *const format, ...):_message(0) { _cimg_exception_err("CImgException",true); }
    CImgException(const CImgException& e):std::exception(e) {
      const size_t size = std::strlen(e._message);
      _message = new char[size + 1];
      std::strncpy(_message,e._message,size);
      _message[size] = 0;
    }
    ~CImgException() { delete[] _message; }
    CImgException& operator=(const CImgException& e) {
      if (this!=&e) { // Protect against self-assignment
        char *new_message = 0;
        if (e._message) {
          const size_t size = std::strlen(e._message);
          new_message = new char[size + 1];
          std::strncpy(new_message,e._message,size);
          new_message[size] = 0;
        }
        delete[] _message;
        _message = new_message;
      }
      return *this;
    }
    //! Return a C-string containing the error message associated with the thrown exception.
    const char *what() const cimg_noexcept { return _message; }
  }; // struct CImgException { ...

  // The CImgAbortException class is used to throw an exception when
  // a computationally-intensive function has been aborted by an external signal.
  struct CImgAbortException : public std::exception {
    char *_message;
    CImgAbortException() { _message = new char[1]; *_message = 0; }
    CImgAbortException(const char *const format, ...):_message(0) { _cimg_exception_err("CImgAbortException",true); }
    CImgAbortException(const CImgAbortException& e):std::exception(e) {
      const size_t size = std::strlen(e._message);
      _message = new char[size + 1];
      std::strncpy(_message,e._message,size);
      _message[size] = 0;
    }
    ~CImgAbortException() { delete[] _message; }
    CImgAbortException& operator=(const CImgAbortException& e) {
      if (this!=&e) { // Protect against self-assignment
        char *new_message = 0;
        if (e._message) {
          const size_t size = std::strlen(e._message);
          new_message = new char[size + 1];
          std::strncpy(new_message,e._message,size);
          new_message[size] = 0;
        }
        delete[] _message;
        _message = new_message;
      }
      return *this;
    }
    //! Return a C-string containing the error message associated with the thrown exception.
    const char *what() const cimg_noexcept { return _message; }
  }; // struct CImgAbortException { ...

  // The CImgArgumentException class is used to throw an exception related
  // to invalid arguments encountered in a library function call.
  struct CImgArgumentException : public CImgException {
    CImgArgumentException(const char *const format, ...) { _cimg_exception_err("CImgArgumentException",true); }
  }; // struct CImgArgumentException { ...

  // The CImgDisplayException class is used to throw an exception related
  // to display problems encountered in a library function call.
  struct CImgDisplayException : public CImgException {
    CImgDisplayException(const char *const format, ...) { _cimg_exception_err("CImgDisplayException",false); }
  }; // struct CImgDisplayException { ...

  // The CImgInstanceException class is used to throw an exception related
  // to an invalid instance encountered in a library function call.
  struct CImgInstanceException : public CImgException {
    CImgInstanceException(const char *const format, ...) { _cimg_exception_err("CImgInstanceException",true); }
  }; // struct CImgInstanceException { ...

  // The CImgIOException class is used to throw an exception related
  // to input/output file problems encountered in a library function call.
  struct CImgIOException : public CImgException {
    CImgIOException(const char *const format, ...) { _cimg_exception_err("CImgIOException",true); }
  }; // struct CImgIOException { ...

  // The CImgWarningException class is used to throw an exception for warnings
  // encountered in a library function call.
  struct CImgWarningException : public CImgException {
    CImgWarningException(const char *const format, ...) { _cimg_exception_err("CImgWarningException",false); }
  }; // struct CImgWarningException { ...

  /*-------------------------------------
    #
    # Define cimg:: namespace
    #
    -----------------------------------*/
  //! Contains low-level functions and variables of the \CImg Library.
  /**
     Most of the functions and variables within this namespace are used by the \CImg library for low-level operations.
     You may use them to access specific const values or environment variables internally used by \CImg.
     \warning Never write <tt>using namespace cimg_library::cimg;</tt> in your source code. A lot of functions in the
     <tt>cimg:: namespace</tt> have the same names as standard C functions that may be defined in the global
     namespace <tt>::</tt>.
  **/
  namespace cimg {

    // Define traits that will be used to determine the best data type to work in CImg functions.
    //
    template<typename T> struct type {
      static const char* string() {
        static const char* s[] = { "unknown",   "unknown8",   "unknown16",  "unknown24",
                                   "unknown32", "unknown40",  "unknown48",  "unknown56",
                                   "unknown64", "unknown72",  "unknown80",  "unknown88",
                                   "unknown96", "unknown104", "unknown112", "unknown120",
                                   "unknown128" };
        return s[(sizeof(T)<17)?sizeof(T):0];
      }
      static bool is_float() { return false; }
      static bool is_inf(const T) { return false; }
      static bool is_nan(const T) { return false; }
      static bool is_finite(const T) { return true; }
      static T min() { return ~max(); }
      static T max() { return (T)1<<(8*sizeof(T) - 1); }
      static T inf() { return max(); }
      static T nan() { return inf(); }
      static T cut(const double val) { return val<(double)min()?min():val>(double)max()?max():(T)val; }
      static const char* format() { return "%s"; }
      static const char* format_s() { return "%s"; }
      static const char* format(const T& val) { static const char *const s = "unknown"; cimg::unused(val); return s; }
    };

    template<> struct type<bool> {
      static const char* string() {
        static const char *const s = "bool";
        return s;
      }
      static bool is_float() { return false; }
      static bool is_inf(const bool) { return false; }
      static bool is_nan(const bool) { return false; }
      static bool is_finite(const bool) { return true; }
      static bool min() { return false; }
      static bool max() { return true; }
      static bool inf() { return max(); }
      static bool nan() { return inf(); }
      static bool is_inf() { return false; }
      static bool cut(const double val) { return val<(double)min()?min():val>(double)max()?max():(bool)val; }
      static const char* format() { return "%s"; }
      static const char* format_s() { return "%s"; }
      static const char* format(const bool val) { static const char* s[] = { "false", "true" }; return s[val?1:0]; }
    };

    template<> struct type<unsigned char> {
      static const char* string() { static const char *const s = "uint8"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const unsigned char) { return false; }
      static bool is_nan(const unsigned char) { return false; }
      static bool is_finite(const unsigned char) { return true; }
      static unsigned char min() { return 0; }
      static unsigned char max() { return (unsigned char)-1; }
      static unsigned char inf() { return max(); }
      static unsigned char nan() { return inf(); }
      static unsigned char cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(unsigned char)val; }
      static const char* format() { return "%u"; }
      static const char* format_s() { return "%u"; }
      static unsigned int format(const unsigned char val) { return (unsigned int)val; }
    };

#if defined(CHAR_MAX) && CHAR_MAX==255
    template<> struct type<char> {
      static const char* string() { static const char *const s = "uint8"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const char) { return false; }
      static bool is_nan(const char) { return false; }
      static bool is_finite(const char) { return true; }
      static char min() { return 0; }
      static char max() { return (char)-1; }
      static char inf() { return max(); }
      static char nan() { return inf(); }
      static char cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(unsigned char)val; }
      static const char* format() { return "%u"; }
      static const char* format_s() { return "%u"; }
      static unsigned int format(const char val) { return (unsigned int)val; }
    };
#else
    template<> struct type<char> {
      static const char* string() { static const char *const s = "int8"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const char) { return false; }
      static bool is_nan(const char) { return false; }
      static bool is_finite(const char) { return true; }
      static char min() { return ~max(); }
      static char max() { return (char)((unsigned char)-1>>1); }
      static char inf() { return max(); }
      static char nan() { return inf(); }
      static char cut(const double val) { return val<(double)min()?min():val>(double)max()?max():(char)val; }
      static const char* format() { return "%d"; }
      static const char* format_s() { return "%d"; }
      static int format(const char val) { return (int)val; }
    };
#endif

    template<> struct type<signed char> {
      static const char* string() { static const char *const s = "int8"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const signed char) { return false; }
      static bool is_nan(const signed char) { return false; }
      static bool is_finite(const signed char) { return true; }
      static signed char min() { return ~max(); }
      static signed char max() { return (signed char)((unsigned char)-1>>1); }
      static signed char inf() { return max(); }
      static signed char nan() { return inf(); }
      static signed char cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(signed char)val; }
      static const char* format() { return "%d"; }
      static const char* format_s() { return "%d"; }
      static int format(const signed char val) { return (int)val; }
    };

    template<> struct type<unsigned short> {
      static const char* string() { static const char *const s = "uint16"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const unsigned short) { return false; }
      static bool is_nan(const unsigned short) { return false; }
      static bool is_finite(const unsigned short) { return true; }
      static unsigned short min() { return 0; }
      static unsigned short max() { return (unsigned short)-1; }
      static unsigned short inf() { return max(); }
      static unsigned short nan() { return inf(); }
      static unsigned short cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(unsigned short)val; }
      static const char* format() { return "%u"; }
      static const char* format_s() { return "%u"; }
      static unsigned int format(const unsigned short val) { return (unsigned int)val; }
    };

    template<> struct type<short> {
      static const char* string() { static const char *const s = "int16"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const short) { return false; }
      static bool is_nan(const short) { return false; }
      static bool is_finite(const short) { return true; }
      static short min() { return ~max(); }
      static short max() { return (short)((unsigned short)-1>>1); }
      static short inf() { return max(); }
      static short nan() { return inf(); }
      static short cut(const double val) { return val<(double)min()?min():val>(double)max()?max():(short)val; }
      static const char* format() { return "%d"; }
      static const char* format_s() { return "%d"; }
      static int format(const short val) { return (int)val; }
    };

    template<> struct type<unsigned int> {
      static const char* string() { static const char *const s = "uint32"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const unsigned int) { return false; }
      static bool is_nan(const unsigned int) { return false; }
      static bool is_finite(const unsigned int) { return true; }
      static unsigned int min() { return 0; }
      static unsigned int max() { return (unsigned int)-1; }
      static unsigned int inf() { return max(); }
      static unsigned int nan() { return inf(); }
      static unsigned int cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(unsigned int)val; }
      static const char* format() { return "%u"; }
      static const char* format_s() { return "%u"; }
      static unsigned int format(const unsigned int val) { return val; }
    };

    template<> struct type<int> {
      static const char* string() { static const char *const s = "int32"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const int) { return false; }
      static bool is_nan(const int) { return false; }
      static bool is_finite(const int) { return true; }
      static int min() { return ~max(); }
      static int max() { return (int)(~0U>>1); }
      static int inf() { return max(); }
      static int nan() { return inf(); }
      static int cut(const double val) { return val<(double)min()?min():val>(double)max()?max():(int)val; }
      static const char* format() { return "%d"; }
      static const char* format_s() { return "%d"; }
      static int format(const int val) { return val; }
    };

    template<> struct type<cimg_uint64> {
      static const char* string() { static const char *const s = "uint64"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const cimg_uint64) { return false; }
      static bool is_nan(const cimg_uint64) { return false; }
      static bool is_finite(const cimg_uint64) { return true; }
      static cimg_uint64 min() { return 0; }
      static cimg_uint64 max() { return (cimg_uint64)-1; }
      static cimg_uint64 inf() { return max(); }
      static cimg_uint64 nan() { return inf(); }
      static cimg_uint64 cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(cimg_uint64)val; }
      static const char* format() { return cimg_fuint64; }
      static const char* format_s() { return cimg_fuint64; }
      static cimg_uint64 format(const cimg_uint64 val) { return val; }
    };

    template<> struct type<cimg_int64> {
      static const char* string() { static const char *const s = "int64"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const cimg_int64) { return false; }
      static bool is_nan(const cimg_int64) { return false; }
      static bool is_finite(const cimg_int64) { return true; }
      static cimg_int64 min() { return ~max(); }
      static cimg_int64 max() { return (cimg_int64)((cimg_uint64)-1>>1); }
      static cimg_int64 inf() { return max(); }
      static cimg_int64 nan() { return inf(); }
      static cimg_int64 cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(cimg_int64)val;
      }
      static const char* format() { return cimg_fint64; }
      static const char* format_s() { return cimg_fint64; }
      static long format(const long val) { return (long)val; }
    };

#if cimg_use_cpp11==1 && \
    (!(UINTPTR_MAX==0xffffffff || defined(__arm__) || defined(_M_ARM) || ((ULONG_MAX)==(UINT_MAX))))
    template<> struct type<unsigned long long> {
      static const char* string() { static const char *const s = "uint64"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const cimg_uint64) { return false; }
      static bool is_nan(const cimg_uint64) { return false; }
      static bool is_finite(const cimg_uint64) { return true; }
      static cimg_uint64 min() { return 0; }
      static cimg_uint64 max() { return (cimg_uint64)-1; }
      static cimg_uint64 inf() { return max(); }
      static cimg_uint64 nan() { return inf(); }
      static cimg_uint64 cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(cimg_uint64)val; }
      static const char* format() { return cimg_fuint64; }
      static const char* format_s() { return cimg_fuint64; }
      static cimg_uint64 format(const cimg_uint64 val) { return val; }
    };

    template<> struct type<long long> {
      static const char* string() { static const char *const s = "int64"; return s; }
      static bool is_float() { return false; }
      static bool is_inf(const cimg_int64) { return false; }
      static bool is_nan(const cimg_int64) { return false; }
      static bool is_finite(const cimg_int64) { return true; }
      static long long min() { return ~max(); }
      static long long max() { return (cimg_int64)((cimg_uint64)-1>>1); }
      static long long inf() { return max(); }
      static long long nan() { return max(); }
      static long long cut(const double val) {
        return val<(double)min()?min():val>(double)max()?max():(cimg_int64)val;
      }
      static const char* format() { return cimg_fint64; }
      static const char* format_s() { return cimg_fint64; }
      static long format(const long val) { return (long)val; }
    };
#endif

    template<> struct type<double> {
      static const char* string() { static const char *const s = "float64"; return s; }
      static bool is_float() { return true; }
      static bool is_inf(const double val) {
        if (sizeof(double)==8) { // Custom version that works with '-ffast-math'
          cimg_uint64 u;
          std::memcpy(&u,&val,sizeof(double));
          return ((unsigned int)(u>>32)&0x7fffffff)==0x7ff00000 && (unsigned int)u==0;
        }
#ifdef isinf
        return (bool)isinf(val);
#else
        return !is_nan(val) && (val<cimg::type<double>::min() || val>cimg::type<double>::max());
#endif
      }
      static bool is_nan(const double val) { // Custom version that works with '-ffast-math'
        if (sizeof(double)==8) {
          cimg_uint64 u;
          std::memcpy(&u,&val,sizeof(double));
          return ((unsigned int)(u>>32)&0x7fffffff) + ((unsigned int)u!=0)>0x7ff00000;
        }
#ifdef isnan
        return (bool)isnan(val);
#else
        return !(val==val);
#endif
      }
      static bool is_finite(const double val) {
#ifdef isfinite
        return (bool)isfinite(val);
#else
        return !is_nan(val) && !is_inf(val);
#endif
      }
      static double min() { return -DBL_MAX; }
      static double max() { return DBL_MAX; }
      static double inf() {
#ifdef INFINITY
        return (double)INFINITY;
#else
        return max()*max();
#endif
      }
      static double nan() {
#ifdef NAN
        return (double)NAN;
#else
        const double val_nan = -std::sqrt(-1.); return val_nan;
#endif
      }
      static double cut(const double val) { return val; }
      static const char* format() { return "%.17g"; }
      static const char* format_s() { return "%g"; }
      static double format(const double val) { return val; }
    };

    template<> struct type<float> {
      static const char* string() { static const char *const s = "float32"; return s; }
      static bool is_float() { return true; }
      static bool is_inf(const float val) {
        if (sizeof(float)==4) { // Custom version that works with '-ffast-math'
          unsigned int u;
          std::memcpy(&u,&val,sizeof(float));
          return (u&0x7fffffff)==0x7f800000;
        }
#ifdef isinf
        return (bool)isinf(val);
#else
        return !is_nan(val) && (val<cimg::type<float>::min() || val>cimg::type<float>::max());
#endif
      }
      static bool is_nan(const float val) { // Custom version that works with '-ffast-math'
        if (sizeof(float)==4) {
          unsigned int u;
          std::memcpy(&u,&val,sizeof(float));
          return (u&0x7fffffff)>0x7f800000;
        }
#ifdef isnan
        return (bool)isnan(val);
#else
        return !(val==val);
#endif
      }
      static bool is_finite(const float val) {
#ifdef isfinite
        return (bool)isfinite(val);
#else
        return !is_nan(val) && !is_inf(val);
#endif
      }
      static float min() { return -FLT_MAX; }
      static float max() { return FLT_MAX; }
      static float inf() { return (float)cimg::type<double>::inf(); }
      static float nan() { return (float)cimg::type<double>::nan(); }
      static float cut(const double val) { return (float)val; }
      static float cut(const float val) { return (float)val; }
      static const char* format() { return "%.9g"; }
      static const char* format_s() { return "%g"; }
      static double format(const float val) { return (double)val; }
    };

    template<> struct type<long double> {
      static const char* string() { static const char *const s = "float128"; return s; }
      static bool is_float() { return true; }
      static bool is_inf(const long double val) {
#ifdef isinf
        return (bool)isinf(val);
#else
        return !is_nan(val) && (val<cimg::type<long double>::min() || val>cimg::type<long double>::max());
#endif
      }
      static bool is_nan(const long double val) {
#ifdef isnan
        return (bool)isnan(val);
#else
        return cimg::type<double>::is_nan((double)val);
#endif
      }
      static bool is_finite(const long double val) {
#ifdef isfinite
        return (bool)isfinite(val);
#else
        return !is_nan(val) && !is_inf(val);
#endif
      }
      static long double min() { return -LDBL_MAX; }
      static long double max() { return LDBL_MAX; }
      static long double inf() { return max()*max(); }
      static long double nan() { const long double val_nan = -std::sqrt(-1.L); return val_nan; }
      static long double cut(const long double val) { return val; }
      static const char* format() { return "%.17g"; }
      static const char* format_s() { return "%g"; }
      static double format(const long double val) { return (double)val; }
    };

#if cimg_is_float16==1
    template<> struct type<cimg_float16> {
      static const char* string() { static const char *const s = "float16"; return s; }
      static bool is_float() { return true; }
      static bool is_inf(const cimg_float16 val) {
        if (sizeof(cimg_float16)==2) { // Custom version that works with '-ffast-math'
          unsigned short u;
          std::memcpy(&u,&val,sizeof(unsigned short));
          return (u&0x7fff)==0x7c00;
        }
        return cimg::type<float>::is_inf((float)val);
      }
      static bool is_nan(const cimg_float16 val) { // Custom version that works with '-ffast-math'
        if (sizeof(cimg_float16)==2) {
          short u;
          std::memcpy(&u,&val,sizeof(short));
          return (bool)((u&0x7fff)>0x7c00);
        }
        return cimg::type<float>::is_nan((float)val);
      }
      static bool is_finite(const cimg_float16 val) {
#ifdef isfinite
        return (bool)isfinite(val);
#else
        return !is_nan(val) && !is_inf(val);
#endif
      }
      static cimg_float16 min() { return (cimg_float16)-65504; }
      static cimg_float16 max() { return (cimg_float16)65504; }
      static cimg_float16 inf() { return max()*max(); }
      static cimg_float16 nan() { const cimg_float16 val_nan = (cimg_float16)-std::sqrt(-1.); return val_nan; }
      static cimg_float16 cut(const double val) { return (cimg_float16)val; }
      static const char* format() { return "%.9g"; }
      static const char* format_s() { return "%g"; }
      static double format(const cimg_float16 val) { return (double)val; }
    };
#endif

    template<typename T, typename t> struct superset { typedef T type; };
    template<> struct superset<bool,unsigned char> { typedef unsigned char type; };
    template<> struct superset<bool,char> { typedef char type; };
    template<> struct superset<bool,signed char> { typedef signed char type; };
    template<> struct superset<bool,unsigned short> { typedef unsigned short type; };
    template<> struct superset<bool,short> { typedef short type; };
    template<> struct superset<bool,unsigned int> { typedef unsigned int type; };
    template<> struct superset<bool,int> { typedef int type; };
    template<> struct superset<bool,cimg_uint64> { typedef cimg_uint64 type; };
    template<> struct superset<bool,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<bool,float> { typedef float type; };
    template<> struct superset<bool,double> { typedef double type; };
    template<> struct superset<unsigned char,char> { typedef short type; };
    template<> struct superset<unsigned char,signed char> { typedef short type; };
    template<> struct superset<unsigned char,unsigned short> { typedef unsigned short type; };
    template<> struct superset<unsigned char,short> { typedef short type; };
    template<> struct superset<unsigned char,unsigned int> { typedef unsigned int type; };
    template<> struct superset<unsigned char,int> { typedef int type; };
    template<> struct superset<unsigned char,cimg_uint64> { typedef cimg_uint64 type; };
    template<> struct superset<unsigned char,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<unsigned char,float> { typedef float type; };
    template<> struct superset<unsigned char,double> { typedef double type; };
    template<> struct superset<signed char,unsigned char> { typedef short type; };
    template<> struct superset<signed char,char> { typedef short type; };
    template<> struct superset<signed char,unsigned short> { typedef int type; };
    template<> struct superset<signed char,short> { typedef short type; };
    template<> struct superset<signed char,unsigned int> { typedef cimg_int64 type; };
    template<> struct superset<signed char,int> { typedef int type; };
    template<> struct superset<signed char,cimg_uint64> { typedef cimg_int64 type; };
    template<> struct superset<signed char,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<signed char,float> { typedef float type; };
    template<> struct superset<signed char,double> { typedef double type; };
    template<> struct superset<char,unsigned char> { typedef short type; };
    template<> struct superset<char,signed char> { typedef short type; };
    template<> struct superset<char,unsigned short> { typedef int type; };
    template<> struct superset<char,short> { typedef short type; };
    template<> struct superset<char,unsigned int> { typedef cimg_int64 type; };
    template<> struct superset<char,int> { typedef int type; };
    template<> struct superset<char,cimg_uint64> { typedef cimg_int64 type; };
    template<> struct superset<char,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<char,float> { typedef float type; };
    template<> struct superset<char,double> { typedef double type; };
    template<> struct superset<unsigned short,char> { typedef int type; };
    template<> struct superset<unsigned short,signed char> { typedef int type; };
    template<> struct superset<unsigned short,short> { typedef int type; };
    template<> struct superset<unsigned short,unsigned int> { typedef unsigned int type; };
    template<> struct superset<unsigned short,int> { typedef int type; };
    template<> struct superset<unsigned short,cimg_uint64> { typedef cimg_uint64 type; };
    template<> struct superset<unsigned short,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<unsigned short,float> { typedef float type; };
    template<> struct superset<unsigned short,double> { typedef double type; };
    template<> struct superset<short,unsigned short> { typedef int type; };
    template<> struct superset<short,unsigned int> { typedef cimg_int64 type; };
    template<> struct superset<short,int> { typedef int type; };
    template<> struct superset<short,cimg_uint64> { typedef cimg_int64 type; };
    template<> struct superset<short,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<short,float> { typedef float type; };
    template<> struct superset<short,double> { typedef double type; };
    template<> struct superset<unsigned int,char> { typedef cimg_int64 type; };
    template<> struct superset<unsigned int,signed char> { typedef cimg_int64 type; };
    template<> struct superset<unsigned int,short> { typedef cimg_int64 type; };
    template<> struct superset<unsigned int,int> { typedef cimg_int64 type; };
    template<> struct superset<unsigned int,cimg_uint64> { typedef cimg_uint64 type; };
    template<> struct superset<unsigned int,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<unsigned int,float> { typedef float type; };
    template<> struct superset<unsigned int,double> { typedef double type; };
    template<> struct superset<int,unsigned int> { typedef cimg_int64 type; };
    template<> struct superset<int,cimg_uint64> { typedef cimg_int64 type; };
    template<> struct superset<int,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<int,float> { typedef float type; };
    template<> struct superset<int,double> { typedef double type; };
    template<> struct superset<cimg_uint64,char> { typedef cimg_int64 type; };
    template<> struct superset<cimg_uint64,signed char> { typedef cimg_int64 type; };
    template<> struct superset<cimg_uint64,short> { typedef cimg_int64 type; };
    template<> struct superset<cimg_uint64,int> { typedef cimg_int64 type; };
    template<> struct superset<cimg_uint64,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<cimg_uint64,float> { typedef double type; };
    template<> struct superset<cimg_uint64,double> { typedef double type; };
    template<> struct superset<cimg_int64,float> { typedef double type; };
    template<> struct superset<cimg_int64,double> { typedef double type; };
#if cimg_use_cpp11==1 && \
    (!(UINTPTR_MAX==0xffffffff || defined(__arm__) || defined(_M_ARM) || ((ULONG_MAX)==(UINT_MAX))))
    template<> struct superset<unsigned long long,char> { typedef cimg_int64 type; };
    template<> struct superset<unsigned long long,signed char> { typedef cimg_int64 type; };
    template<> struct superset<unsigned long long,short> { typedef cimg_int64 type; };
    template<> struct superset<unsigned long long,int> { typedef cimg_int64 type; };
    template<> struct superset<unsigned long long,cimg_int64> { typedef cimg_int64 type; };
    template<> struct superset<unsigned long long,float> { typedef double type; };
    template<> struct superset<unsigned long long,double> { typedef double type; };
    template<> struct superset<long long,float> { typedef double type; };
    template<> struct superset<long long,double> { typedef double type; };
#endif
    template<> struct superset<float,cimg_uint64> { typedef double type; };
    template<> struct superset<float,cimg_int64> { typedef double type; };
    template<> struct superset<float,double> { typedef double type; };
#if cimg_is_float16==1
    template<> struct superset<cimg_float16,unsigned short> { typedef float type; };
    template<> struct superset<cimg_float16,short> { typedef float type; };
    template<> struct superset<cimg_float16,unsigned int> { typedef float type; };
    template<> struct superset<cimg_float16,int> { typedef float type; };
    template<> struct superset<cimg_float16,cimg_uint64> { typedef float type; };
    template<> struct superset<cimg_float16,cimg_int64> { typedef float type; };
    template<> struct superset<cimg_float16,float> { typedef float type; };
    template<> struct superset<cimg_float16,double> { typedef double type; };
#endif

    template<typename t1, typename t2, typename t3> struct superset2 {
      typedef typename superset<t1, typename superset<t2,t3>::type>::type type;
    };

    template<typename t1, typename t2, typename t3, typename t4> struct superset3 {
      typedef typename superset<t1, typename superset2<t2,t3,t4>::type>::type type;
    };

    template<typename t1, typename t2> struct last { typedef t2 type; };

#define _cimg_Tt typename cimg::superset<T,t>::type
#define _cimg_Tfloat typename cimg::superset<T,float>::type
#define _cimg_tfloat typename cimg::superset<t,float>::type
#define _cimg_Ttfloat typename cimg::superset2<T,t,float>::type
#define _cimg_Ttdouble typename cimg::superset2<T,t,double>::type

    // Define variables used internally by CImg.
#if cimg_display==1
    struct X11_attr {
      CImgDisplay **cimg_displays;
      unsigned int nb_cimg_displays;
      Display *display;
      pthread_t *events_thread;
      pthread_cond_t wait_event;
      pthread_mutex_t mutex_lock_display, mutex_wait_event;
      pthread_mutexattr_t attr;
      unsigned int nb_bits;
      bool is_blue_first, is_shm_enabled, byte_order, events_thread_running;

#ifdef cimg_use_xrandr
      XRRScreenSize *resolutions;
      Rotation curr_rotation;
      unsigned int curr_resolution, nb_resolutions;
#endif
      X11_attr():nb_cimg_displays(0),display(0),events_thread(0),nb_bits(0),
                 is_blue_first(false),is_shm_enabled(false),byte_order(false),events_thread_running(false) {
#ifdef __FreeBSD__
        XInitThreads();
#endif
	pthread_mutexattr_init(&attr);
	pthread_mutexattr_settype(&attr,PTHREAD_MUTEX_RECURSIVE);
        pthread_mutex_init(&mutex_wait_event, &attr);
        pthread_mutex_init(&mutex_lock_display, &attr);
        pthread_cond_init(&wait_event,0);
#ifdef cimg_use_xrandr
        resolutions = 0;
        curr_rotation = 0;
        curr_resolution = nb_resolutions = 0;
#endif
        cimg_displays = new CImgDisplay*[512];
      }

      ~X11_attr() {
        unlock();
        if (events_thread) {
          terminate_events_thread();
          delete events_thread;
        }
        pthread_cond_destroy(&wait_event);
        pthread_mutex_unlock(&mutex_wait_event);
        pthread_mutex_destroy(&mutex_wait_event);
        pthread_mutex_unlock(&mutex_lock_display);
        pthread_mutex_destroy(&mutex_lock_display);
        delete[] cimg_displays;
        if (display) { XCloseDisplay(display); }
      }

      X11_attr& lock() { // Lock display
        pthread_mutex_lock(&mutex_lock_display);
        return *this;
      }

      X11_attr& unlock() { // Unlock display
        pthread_mutex_unlock(&mutex_lock_display);
        return *this;
      }

      X11_attr& terminate_events_thread() {
        events_thread_running = false;
        pthread_join(*events_thread,0);
        delete events_thread;
        events_thread = 0;
        return *this;
      }

      static X11_attr& ref() { // Return shared instance across compilation modules
        static X11_attr ref;
        return ref;
      }

    }; // struct X11_attr { ...

#elif cimg_display==2
    struct Win32_attr {
      HANDLE wait_event;

      Win32_attr() {
        wait_event = CreateEvent(0,FALSE_WIN,FALSE_WIN,0);
      }

      static Win32_attr& ref() { // Return shared instance across compilation modules
        static Win32_attr ref;
        return ref;
      }
    }; // struct Win32_attr { ...

#elif cimg_display==3
    struct SDL3_attr {
      CImgDisplay **cimg_displays;
      unsigned int nb_cimg_displays;
      SDL_DisplayID display;
      SDL_ThreadID main_thread_id;
      const SDL_DisplayMode *mode;
      SDL_Mutex *mutex_lock_display;

      SDL3_attr():nb_cimg_displays(0),display(0),mode(0),mutex_lock_display(0) {
        bool init_failed = true;
        if (SDL_Init(SDL_INIT_VIDEO)) {
          display = SDL_GetPrimaryDisplay();
          if (display) {
            mode = SDL_GetCurrentDisplayMode(display);
            if (mode) {
              mutex_lock_display = SDL_CreateMutex();
              if (mutex_lock_display) init_failed = false;
              main_thread_id = SDL_GetCurrentThreadID();
            }
          }
        }
#if cimg_OS==1
        std::signal(SIGINT,SIG_DFL); // Restore default behavior for CTRL+C
#endif
        if (init_failed) {
          if (mutex_lock_display) {
            SDL_DestroyMutex(mutex_lock_display);
          }
          SDL_Quit();
          throw CImgDisplayException("cimg::SDL3_attr(): %s", SDL_GetError());
        }
        cimg_displays = new CImgDisplay*[512];
      }

      ~SDL3_attr() {
        unlock();
        SDL_DestroyMutex(mutex_lock_display);
        SDL_Quit();
        delete[] cimg_displays;
      }

      SDL3_attr& lock() { // Lock display
        SDL_LockMutex(mutex_lock_display);
        return *this;
      }

      SDL3_attr& unlock() { // Unlock display
        SDL_UnlockMutex(mutex_lock_display);
        return *this;
      }

      static SDL3_attr& ref() { // Return shared instance across compilation modules
        static SDL3_attr ref;
        return ref;
      }

    }; // struct SDL3_attr { ...

#endif

    struct Mutex_attr {
#if cimg_OS==1 && cimg_use_pthread==1
      pthread_mutex_t mutex[32];
      Mutex_attr() { for (unsigned int i = 0; i<32; ++i) pthread_mutex_init(&mutex[i],0); }
      ~Mutex_attr() { for (unsigned int i = 0; i<32; ++i) pthread_mutex_destroy(&mutex[i]); }
      void lock(const unsigned int n) { pthread_mutex_lock(&mutex[n]); }
      void unlock(const unsigned int n) { pthread_mutex_unlock(&mutex[n]); }
      int trylock(const unsigned int n) { return pthread_mutex_trylock(&mutex[n]); }
#elif cimg_OS==2
      HANDLE mutex[32];
      Mutex_attr() { for (unsigned int i = 0; i<32; ++i) mutex[i] = CreateMutex(0,FALSE_WIN,0); }
      ~Mutex_attr() { for (unsigned int i = 0; i<32; ++i) CloseHandle(mutex[i]); }
      void lock(const unsigned int n) { WaitForSingleObject(mutex[n],INFINITE); }
      void unlock(const unsigned int n) { ReleaseMutex(mutex[n]); }
      int trylock(const unsigned int) { return 0; }
#else
      Mutex_attr() {}
      ~Mutex_attr() {}
      void lock(const unsigned int) {}
      void unlock(const unsigned int) {}
      int trylock(const unsigned int) { return 0; }
#endif
      static Mutex_attr &ref() { // Return shared instance across compilation modules
        static Mutex_attr ref;
        return ref;
      }
    }; // struct Mutex_attr { ...

#if defined(cimg_use_magick)
    struct Magick_static {
      Magick_static() {
        Magick::InitializeMagick("");
      }
    }; // struct Magick_static { ...
    static Magick_static _Magick_static;
#endif

#if defined(cimg_use_fftw3) && !defined(cimg_use_fftw3_singlethread)
    struct FFTW3_static {
      FFTW3_static() {
        fftw_init_threads();
      }
    }; // struct FFTW3_static { ...
    static FFTW3_static _FFTW3_static;
#endif

#if cimg_display==1
    // Define keycodes for X11-based display (Unix).
    const unsigned int keyESC        = XK_Escape;
    const unsigned int keyF1         = XK_F1;
    const unsigned int keyF2         = XK_F2;
    const unsigned int keyF3         = XK_F3;
    const unsigned int keyF4         = XK_F4;
    const unsigned int keyF5         = XK_F5;
    const unsigned int keyF6         = XK_F6;
    const unsigned int keyF7         = XK_F7;
    const unsigned int keyF8         = XK_F8;
    const unsigned int keyF9         = XK_F9;
    const unsigned int keyF10        = XK_F10;
    const unsigned int keyF11        = XK_F11;
    const unsigned int keyF12        = XK_F12;
    const unsigned int keyPAUSE      = XK_Pause;
    const unsigned int key1          = XK_1;
    const unsigned int key2          = XK_2;
    const unsigned int key3          = XK_3;
    const unsigned int key4          = XK_4;
    const unsigned int key5          = XK_5;
    const unsigned int key6          = XK_6;
    const unsigned int key7          = XK_7;
    const unsigned int key8          = XK_8;
    const unsigned int key9          = XK_9;
    const unsigned int key0          = XK_0;
    const unsigned int keyBACKSPACE  = XK_BackSpace;
    const unsigned int keyINSERT     = XK_Insert;
    const unsigned int keyHOME       = XK_Home;
    const unsigned int keyPAGEUP     = XK_Page_Up;
    const unsigned int keyTAB        = XK_Tab;
    const unsigned int keyQ          = XK_q;
    const unsigned int keyW          = XK_w;
    const unsigned int keyE          = XK_e;
    const unsigned int keyR          = XK_r;
    const unsigned int keyT          = XK_t;
    const unsigned int keyY          = XK_y;
    const unsigned int keyU          = XK_u;
    const unsigned int keyI          = XK_i;
    const unsigned int keyO          = XK_o;
    const unsigned int keyP          = XK_p;
    const unsigned int keyDELETE     = XK_Delete;
    const unsigned int keyEND        = XK_End;
    const unsigned int keyPAGEDOWN   = XK_Page_Down;
    const unsigned int keyCAPSLOCK   = XK_Caps_Lock;
    const unsigned int keyA          = XK_a;
    const unsigned int keyS          = XK_s;
    const unsigned int keyD          = XK_d;
    const unsigned int keyF          = XK_f;
    const unsigned int keyG          = XK_g;
    const unsigned int keyH          = XK_h;
    const unsigned int keyJ          = XK_j;
    const unsigned int keyK          = XK_k;
    const unsigned int keyL          = XK_l;
    const unsigned int keyRETURN     = XK_Return;
    const unsigned int keySHIFTLEFT  = XK_Shift_L;
    const unsigned int keyZ          = XK_z;
    const unsigned int keyX          = XK_x;
    const unsigned int keyC          = XK_c;
    const unsigned int keyV          = XK_v;
    const unsigned int keyB          = XK_b;
    const unsigned int keyN          = XK_n;
    const unsigned int keyM          = XK_m;
    const unsigned int keySHIFTRIGHT = XK_Shift_R;
    const unsigned int keyARROWUP    = XK_Up;
    const unsigned int keyCTRLLEFT   = XK_Control_L;
    const unsigned int keyAPPLEFT    = XK_Super_L;
    const unsigned int keyALT        = XK_Alt_L;
    const unsigned int keySPACE      = XK_space;
    const unsigned int keyALTGR      = XK_Alt_R;
    const unsigned int keyAPPRIGHT   = XK_Super_R;
    const unsigned int keyMENU       = XK_Menu;
    const unsigned int keyCTRLRIGHT  = XK_Control_R;
    const unsigned int keyARROWLEFT  = XK_Left;
    const unsigned int keyARROWDOWN  = XK_Down;
    const unsigned int keyARROWRIGHT = XK_Right;
    const unsigned int keyPAD0       = XK_KP_0;
    const unsigned int keyPAD1       = XK_KP_1;
    const unsigned int keyPAD2       = XK_KP_2;
    const unsigned int keyPAD3       = XK_KP_3;
    const unsigned int keyPAD4       = XK_KP_4;
    const unsigned int keyPAD5       = XK_KP_5;
    const unsigned int keyPAD6       = XK_KP_6;
    const unsigned int keyPAD7       = XK_KP_7;
    const unsigned int keyPAD8       = XK_KP_8;
    const unsigned int keyPAD9       = XK_KP_9;
    const unsigned int keyPADADD     = XK_KP_Add;
    const unsigned int keyPADSUB     = XK_KP_Subtract;
    const unsigned int keyPADMUL     = XK_KP_Multiply;
    const unsigned int keyPADDIV     = XK_KP_Divide;
    const unsigned int keyENTER      = XK_KP_Enter;

#elif cimg_display==2
    // Define keycodes for GDI32-based display (Windows).
    const unsigned int keyESC        = VK_ESCAPE;
    const unsigned int keyF1         = VK_F1;
    const unsigned int keyF2         = VK_F2;
    const unsigned int keyF3         = VK_F3;
    const unsigned int keyF4         = VK_F4;
    const unsigned int keyF5         = VK_F5;
    const unsigned int keyF6         = VK_F6;
    const unsigned int keyF7         = VK_F7;
    const unsigned int keyF8         = VK_F8;
    const unsigned int keyF9         = VK_F9;
    const unsigned int keyF10        = VK_F10;
    const unsigned int keyF11        = VK_F11;
    const unsigned int keyF12        = VK_F12;
    const unsigned int keyPAUSE      = VK_PAUSE;
    const unsigned int key1          = '1';
    const unsigned int key2          = '2';
    const unsigned int key3          = '3';
    const unsigned int key4          = '4';
    const unsigned int key5          = '5';
    const unsigned int key6          = '6';
    const unsigned int key7          = '7';
    const unsigned int key8          = '8';
    const unsigned int key9          = '9';
    const unsigned int key0          = '0';
    const unsigned int keyBACKSPACE  = VK_BACK;
    const unsigned int keyINSERT     = VK_INSERT;
    const unsigned int keyHOME       = VK_HOME;
    const unsigned int keyPAGEUP     = VK_PRIOR;
    const unsigned int keyTAB        = VK_TAB;
    const unsigned int keyQ          = 'Q';
    const unsigned int keyW          = 'W';
    const unsigned int keyE          = 'E';
    const unsigned int keyR          = 'R';
    const unsigned int keyT          = 'T';
    const unsigned int keyY          = 'Y';
    const unsigned int keyU          = 'U';
    const unsigned int keyI          = 'I';
    const unsigned int keyO          = 'O';
    const unsigned int keyP          = 'P';
    const unsigned int keyDELETE     = VK_DELETE;
    const unsigned int keyEND        = VK_END;
    const unsigned int keyPAGEDOWN   = VK_NEXT;
    const unsigned int keyCAPSLOCK   = VK_CAPITAL;
    const unsigned int keyA          = 'A';
    const unsigned int keyS          = 'S';
    const unsigned int keyD          = 'D';
    const unsigned int keyF          = 'F';
    const unsigned int keyG          = 'G';
    const unsigned int keyH          = 'H';
    const unsigned int keyJ          = 'J';
    const unsigned int keyK          = 'K';
    const unsigned int keyL          = 'L';
    const unsigned int keyRETURN     = VK_RETURN;
    const unsigned int keySHIFTLEFT  = VK_SHIFT;
    const unsigned int keyZ          = 'Z';
    const unsigned int keyX          = 'X';
    const unsigned int keyC          = 'C';
    const unsigned int keyV          = 'V';
    const unsigned int keyB          = 'B';
    const unsigned int keyN          = 'N';
    const unsigned int keyM          = 'M';
    const unsigned int keySHIFTRIGHT = VK_SHIFT;
    const unsigned int keyARROWUP    = VK_UP;
    const unsigned int keyCTRLLEFT   = VK_CONTROL;
    const unsigned int keyAPPLEFT    = VK_LWIN;
    const unsigned int keyALT        = VK_LMENU;
    const unsigned int keySPACE      = VK_SPACE;
    const unsigned int keyALTGR      = VK_CONTROL;
    const unsigned int keyAPPRIGHT   = VK_RWIN;
    const unsigned int keyMENU       = VK_APPS;
    const unsigned int keyCTRLRIGHT  = VK_CONTROL;
    const unsigned int keyARROWLEFT  = VK_LEFT;
    const unsigned int keyARROWDOWN  = VK_DOWN;
    const unsigned int keyARROWRIGHT = VK_RIGHT;
    const unsigned int keyPAD0       = 0x60;
    const unsigned int keyPAD1       = 0x61;
    const unsigned int keyPAD2       = 0x62;
    const unsigned int keyPAD3       = 0x63;
    const unsigned int keyPAD4       = 0x64;
    const unsigned int keyPAD5       = 0x65;
    const unsigned int keyPAD6       = 0x66;
    const unsigned int keyPAD7       = 0x67;
    const unsigned int keyPAD8       = 0x68;
    const unsigned int keyPAD9       = 0x69;
    const unsigned int keyPADADD     = VK_ADD;
    const unsigned int keyPADSUB     = VK_SUBTRACT;
    const unsigned int keyPADMUL     = VK_MULTIPLY;
    const unsigned int keyPADDIV     = VK_DIVIDE;
    const unsigned int keyENTER      = VK_RETURN;

#elif cimg_display==3
    // Define keycodes for SDL3-based display.
    const unsigned int keyESC        = SDL_SCANCODE_ESCAPE;
    const unsigned int keyF1         = SDL_SCANCODE_F1;
    const unsigned int keyF2         = SDL_SCANCODE_F2;
    const unsigned int keyF3         = SDL_SCANCODE_F3;
    const unsigned int keyF4         = SDL_SCANCODE_F4;
    const unsigned int keyF5         = SDL_SCANCODE_F5;
    const unsigned int keyF6         = SDL_SCANCODE_F6;
    const unsigned int keyF7         = SDL_SCANCODE_F7;
    const unsigned int keyF8         = SDL_SCANCODE_F8;
    const unsigned int keyF9         = SDL_SCANCODE_F9;
    const unsigned int keyF10        = SDL_SCANCODE_F10;
    const unsigned int keyF11        = SDL_SCANCODE_F11;
    const unsigned int keyF12        = SDL_SCANCODE_F12;
    const unsigned int keyPAUSE      = SDL_SCANCODE_PAUSE;
    const unsigned int key1          = SDL_SCANCODE_1;
    const unsigned int key2          = SDL_SCANCODE_2;
    const unsigned int key3          = SDL_SCANCODE_3;
    const unsigned int key4          = SDL_SCANCODE_4;
    const unsigned int key5          = SDL_SCANCODE_5;
    const unsigned int key6          = SDL_SCANCODE_6;
    const unsigned int key7          = SDL_SCANCODE_7;
    const unsigned int key8          = SDL_SCANCODE_8;
    const unsigned int key9          = SDL_SCANCODE_9;
    const unsigned int key0          = SDL_SCANCODE_0;
    const unsigned int keyBACKSPACE  = SDL_SCANCODE_BACKSPACE;
    const unsigned int keyINSERT     = SDL_SCANCODE_INSERT;
    const unsigned int keyHOME       = SDL_SCANCODE_HOME;
    const unsigned int keyPAGEUP     = SDL_SCANCODE_PAGEUP;
    const unsigned int keyTAB        = SDL_SCANCODE_TAB;
    const unsigned int keyQ          = SDL_SCANCODE_Q;
    const unsigned int keyW          = SDL_SCANCODE_W;
    const unsigned int keyE          = SDL_SCANCODE_E;
    const unsigned int keyR          = SDL_SCANCODE_R;
    const unsigned int keyT          = SDL_SCANCODE_T;
    const unsigned int keyY          = SDL_SCANCODE_Y;
    const unsigned int keyU          = SDL_SCANCODE_U;
    const unsigned int keyI          = SDL_SCANCODE_I;
    const unsigned int keyO          = SDL_SCANCODE_O;
    const unsigned int keyP          = SDL_SCANCODE_P;
    const unsigned int keyDELETE     = SDL_SCANCODE_DELETE;
    const unsigned int keyEND        = SDL_SCANCODE_END;
    const unsigned int keyPAGEDOWN   = SDL_SCANCODE_PAGEDOWN;
    const unsigned int keyCAPSLOCK   = SDL_SCANCODE_CAPSLOCK;
    const unsigned int keyA          = SDL_SCANCODE_A;
    const unsigned int keyS          = SDL_SCANCODE_S;
    const unsigned int keyD          = SDL_SCANCODE_D;
    const unsigned int keyF          = SDL_SCANCODE_F;
    const unsigned int keyG          = SDL_SCANCODE_G;
    const unsigned int keyH          = SDL_SCANCODE_H;
    const unsigned int keyJ          = SDL_SCANCODE_J;
    const unsigned int keyK          = SDL_SCANCODE_K;
    const unsigned int keyL          = SDL_SCANCODE_L;
    const unsigned int keyRETURN     = SDL_SCANCODE_RETURN;
    const unsigned int keySHIFTLEFT  = SDL_SCANCODE_LSHIFT;
    const unsigned int keyZ          = SDL_SCANCODE_Z;
    const unsigned int keyX          = SDL_SCANCODE_X;
    const unsigned int keyC          = SDL_SCANCODE_C;
    const unsigned int keyV          = SDL_SCANCODE_V;
    const unsigned int keyB          = SDL_SCANCODE_B;
    const unsigned int keyN          = SDL_SCANCODE_N;
    const unsigned int keyM          = SDL_SCANCODE_M;
    const unsigned int keySHIFTRIGHT = SDL_SCANCODE_RSHIFT;
    const unsigned int keyARROWUP    = SDL_SCANCODE_UP;
    const unsigned int keyCTRLLEFT   = SDL_SCANCODE_LCTRL;
    const unsigned int keyAPPLEFT    = SDL_SCANCODE_LGUI;
    const unsigned int keyALT        = SDL_SCANCODE_LALT;
    const unsigned int keySPACE      = SDL_SCANCODE_SPACE;
    const unsigned int keyALTGR      = SDL_SCANCODE_RALT;
    const unsigned int keyAPPRIGHT   = SDL_SCANCODE_RGUI;
    const unsigned int keyMENU       = SDL_SCANCODE_MENU;
    const unsigned int keyCTRLRIGHT  = SDL_SCANCODE_RCTRL;
    const unsigned int keyARROWLEFT  = SDL_SCANCODE_LEFT;
    const unsigned int keyARROWDOWN  = SDL_SCANCODE_DOWN;
    const unsigned int keyARROWRIGHT = SDL_SCANCODE_RIGHT;
    const unsigned int keyPAD0       = SDL_SCANCODE_KP_0;
    const unsigned int keyPAD1       = SDL_SCANCODE_KP_1;
    const unsigned int keyPAD2       = SDL_SCANCODE_KP_2;
    const unsigned int keyPAD3       = SDL_SCANCODE_KP_3;
    const unsigned int keyPAD4       = SDL_SCANCODE_KP_4;
    const unsigned int keyPAD5       = SDL_SCANCODE_KP_5;
    const unsigned int keyPAD6       = SDL_SCANCODE_KP_6;
    const unsigned int keyPAD7       = SDL_SCANCODE_KP_7;
    const unsigned int keyPAD8       = SDL_SCANCODE_KP_8;
    const unsigned int keyPAD9       = SDL_SCANCODE_KP_9;
    const unsigned int keyPADADD     = SDL_SCANCODE_KP_PLUS;
    const unsigned int keyPADSUB     = SDL_SCANCODE_KP_MINUS;
    const unsigned int keyPADMUL     = SDL_SCANCODE_KP_MULTIPLY;
    const unsigned int keyPADDIV     = SDL_SCANCODE_KP_DIVIDE;
    const unsigned int keyENTER      = SDL_SCANCODE_KP_ENTER;

#else
    // Define random keycodes when no display is available.
    // (should rarely be used then!).
    const unsigned int keyESC        = 1U; //!< Keycode for the \c ESC key (architecture-dependent)
    const unsigned int keyF1         = 2U; //!< Keycode for the \c F1 key (architecture-dependent)
    const unsigned int keyF2         = 3U; //!< Keycode for the \c F2 key (architecture-dependent)
    const unsigned int keyF3         = 4U; //!< Keycode for the \c F3 key (architecture-dependent)
    const unsigned int keyF4         = 5U; //!< Keycode for the \c F4 key (architecture-dependent)
    const unsigned int keyF5         = 6U; //!< Keycode for the \c F5 key (architecture-dependent)
    const unsigned int keyF6         = 7U; //!< Keycode for the \c F6 key (architecture-dependent)
    const unsigned int keyF7         = 8U; //!< Keycode for the \c F7 key (architecture-dependent)
    const unsigned int keyF8         = 9U; //!< Keycode for the \c F8 key (architecture-dependent)
    const unsigned int keyF9         = 10U; //!< Keycode for the \c F9 key (architecture-dependent)
    const unsigned int keyF10        = 11U; //!< Keycode for the \c F10 key (architecture-dependent)
    const unsigned int keyF11        = 12U; //!< Keycode for the \c F11 key (architecture-dependent)
    const unsigned int keyF12        = 13U; //!< Keycode for the \c F12 key (architecture-dependent)
    const unsigned int keyPAUSE      = 14U; //!< Keycode for the \c PAUSE key (architecture-dependent)
    const unsigned int key1          = 15U; //!< Keycode for the \c 1 key (architecture-dependent)
    const unsigned int key2          = 16U; //!< Keycode for the \c 2 key (architecture-dependent)
    const unsigned int key3          = 17U; //!< Keycode for the \c 3 key (architecture-dependent)
    const unsigned int key4          = 18U; //!< Keycode for the \c 4 key (architecture-dependent)
    const unsigned int key5          = 19U; //!< Keycode for the \c 5 key (architecture-dependent)
    const unsigned int key6          = 20U; //!< Keycode for the \c 6 key (architecture-dependent)
    const unsigned int key7          = 21U; //!< Keycode for the \c 7 key (architecture-dependent)
    const unsigned int key8          = 22U; //!< Keycode for the \c 8 key (architecture-dependent)
    const unsigned int key9          = 23U; //!< Keycode for the \c 9 key (architecture-dependent)
    const unsigned int key0          = 24U; //!< Keycode for the \c 0 key (architecture-dependent)
    const unsigned int keyBACKSPACE  = 25U; //!< Keycode for the \c BACKSPACE key (architecture-dependent)
    const unsigned int keyINSERT     = 26U; //!< Keycode for the \c INSERT key (architecture-dependent)
    const unsigned int keyHOME       = 27U; //!< Keycode for the \c HOME key (architecture-dependent)
    const unsigned int keyPAGEUP     = 28U; //!< Keycode for the \c PAGEUP key (architecture-dependent)
    const unsigned int keyTAB        = 29U; //!< Keycode for the \c TAB key (architecture-dependent)
    const unsigned int keyQ          = 30U; //!< Keycode for the \c Q key (architecture-dependent)
    const unsigned int keyW          = 31U; //!< Keycode for the \c W key (architecture-dependent)
    const unsigned int keyE          = 32U; //!< Keycode for the \c E key (architecture-dependent)
    const unsigned int keyR          = 33U; //!< Keycode for the \c R key (architecture-dependent)
    const unsigned int keyT          = 34U; //!< Keycode for the \c T key (architecture-dependent)
    const unsigned int keyY          = 35U; //!< Keycode for the \c Y key (architecture-dependent)
    const unsigned int keyU          = 36U; //!< Keycode for the \c U key (architecture-dependent)
    const unsigned int keyI          = 37U; //!< Keycode for the \c I key (architecture-dependent)
    const unsigned int keyO          = 38U; //!< Keycode for the \c O key (architecture-dependent)
    const unsigned int keyP          = 39U; //!< Keycode for the \c P key (architecture-dependent)
    const unsigned int keyDELETE     = 40U; //!< Keycode for the \c DELETE key (architecture-dependent)
    const unsigned int keyEND        = 41U; //!< Keycode for the \c END key (architecture-dependent)
    const unsigned int keyPAGEDOWN   = 42U; //!< Keycode for the \c PAGEDOWN key (architecture-dependent)
    const unsigned int keyCAPSLOCK   = 43U; //!< Keycode for the \c CAPSLOCK key (architecture-dependent)
    const unsigned int keyA          = 44U; //!< Keycode for the \c A key (architecture-dependent)
    const unsigned int keyS          = 45U; //!< Keycode for the \c S key (architecture-dependent)
    const unsigned int keyD          = 46U; //!< Keycode for the \c D key (architecture-dependent)
    const unsigned int keyF          = 47U; //!< Keycode for the \c F key (architecture-dependent)
    const unsigned int keyG          = 48U; //!< Keycode for the \c G key (architecture-dependent)
    const unsigned int keyH          = 49U; //!< Keycode for the \c H key (architecture-dependent)
    const unsigned int keyJ          = 50U; //!< Keycode for the \c J key (architecture-dependent)
    const unsigned int keyK          = 51U; //!< Keycode for the \c K key (architecture-dependent)
    const unsigned int keyL          = 52U; //!< Keycode for the \c L key (architecture-dependent)
    const unsigned int keyRETURN     = 53U; //!< Keycode for the \c RETURN key (architecture-dependent)
    const unsigned int keySHIFTLEFT  = 54U; //!< Keycode for the \c SHIFTLEFT key (architecture-dependent)
    const unsigned int keyZ          = 55U; //!< Keycode for the \c Z key (architecture-dependent)
    const unsigned int keyX          = 56U; //!< Keycode for the \c X key (architecture-dependent)
    const unsigned int keyC          = 57U; //!< Keycode for the \c C key (architecture-dependent)
    const unsigned int keyV          = 58U; //!< Keycode for the \c V key (architecture-dependent)
    const unsigned int keyB          = 59U; //!< Keycode for the \c B key (architecture-dependent)
    const unsigned int keyN          = 60U; //!< Keycode for the \c N key (architecture-dependent)
    const unsigned int keyM          = 61U; //!< Keycode for the \c M key (architecture-dependent)
    const unsigned int keySHIFTRIGHT = 62U; //!< Keycode for the \c SHIFTRIGHT key (architecture-dependent)
    const unsigned int keyARROWUP    = 63U; //!< Keycode for the \c ARROWUP key (architecture-dependent)
    const unsigned int keyCTRLLEFT   = 64U; //!< Keycode for the \c CTRLLEFT key (architecture-dependent)
    const unsigned int keyAPPLEFT    = 65U; //!< Keycode for the \c APPLEFT key (architecture-dependent)
    const unsigned int keyALT        = 66U; //!< Keycode for the \c ALT key (architecture-dependent)
    const unsigned int keySPACE      = 67U; //!< Keycode for the \c SPACE key (architecture-dependent)
    const unsigned int keyALTGR      = 68U; //!< Keycode for the \c ALTGR key (architecture-dependent)
    const unsigned int keyAPPRIGHT   = 69U; //!< Keycode for the \c APPRIGHT key (architecture-dependent)
    const unsigned int keyMENU       = 70U; //!< Keycode for the \c MENU key (architecture-dependent)
    const unsigned int keyCTRLRIGHT  = 71U; //!< Keycode for the \c CTRLRIGHT key (architecture-dependent)
    const unsigned int keyARROWLEFT  = 72U; //!< Keycode for the \c ARROWLEFT key (architecture-dependent)
    const unsigned int keyARROWDOWN  = 73U; //!< Keycode for the \c ARROWDOWN key (architecture-dependent)
    const unsigned int keyARROWRIGHT = 74U; //!< Keycode for the \c ARROWRIGHT key (architecture-dependent)
    const unsigned int keyPAD0       = 75U; //!< Keycode for the \c PAD0 key (architecture-dependent)
    const unsigned int keyPAD1       = 76U; //!< Keycode for the \c PAD1 key (architecture-dependent)
    const unsigned int keyPAD2       = 77U; //!< Keycode for the \c PAD2 key (architecture-dependent)
    const unsigned int keyPAD3       = 78U; //!< Keycode for the \c PAD3 key (architecture-dependent)
    const unsigned int keyPAD4       = 79U; //!< Keycode for the \c PAD4 key (architecture-dependent)
    const unsigned int keyPAD5       = 80U; //!< Keycode for the \c PAD5 key (architecture-dependent)
    const unsigned int keyPAD6       = 81U; //!< Keycode for the \c PAD6 key (architecture-dependent)
    const unsigned int keyPAD7       = 82U; //!< Keycode for the \c PAD7 key (architecture-dependent)
    const unsigned int keyPAD8       = 83U; //!< Keycode for the \c PAD8 key (architecture-dependent)
    const unsigned int keyPAD9       = 84U; //!< Keycode for the \c PAD9 key (architecture-dependent)
    const unsigned int keyPADADD     = 85U; //!< Keycode for the \c PADADD key (architecture-dependent)
    const unsigned int keyPADSUB     = 86U; //!< Keycode for the \c PADSUB key (architecture-dependent)
    const unsigned int keyPADMUL     = 87U; //!< Keycode for the \c PADMUL key (architecture-dependent)
    const unsigned int keyPADDIV     = 88U; //!< Keycode for the \c PADDDIV key (architecture-dependent)
    const unsigned int keyENTER      = 89U; //!< Keycode for the \c ENTER key (architecture-dependent)
#endif

    const double PI = 3.14159265358979323846; //!< Value of the mathematical constant PI

    // Define predefined font graphics with various sizes.
    inline const char* data_font_small();
    inline const char* data_font_normal();
    inline const char* data_font_large();
    inline const char* data_font_huge();

    // Define a 40x38 'danger' color logo (used by cimg::dialog()).
    inline const unsigned char* logo40x38_data() {
      static const unsigned char data[] = {
        177,200,200,200,3,123,123,0,36,200,200,200,1,123,123,0,2,255,255,0,1,189,189,189,1,0,0,0,34,200,200,200,
        1,123,123,0,4,255,255,0,1,189,189,189,1,0,0,0,1,123,123,123,32,200,200,200,1,123,123,0,5,255,255,0,1,0,0,
        0,2,123,123,123,30,200,200,200,1,123,123,0,6,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,29,200,200,200,
        1,123,123,0,7,255,255,0,1,0,0,0,2,123,123,123,28,200,200,200,1,123,123,0,8,255,255,0,1,189,189,189,1,0,0,0,
        2,123,123,123,27,200,200,200,1,123,123,0,9,255,255,0,1,0,0,0,2,123,123,123,26,200,200,200,1,123,123,0,10,255,
        255,0,1,189,189,189,1,0,0,0,2,123,123,123,25,200,200,200,1,123,123,0,3,255,255,0,1,189,189,189,3,0,0,0,1,189,
        189,189,3,255,255,0,1,0,0,0,2,123,123,123,24,200,200,200,1,123,123,0,4,255,255,0,5,0,0,0,3,255,255,0,1,189,
        189,189,1,0,0,0,2,123,123,123,23,200,200,200,1,123,123,0,4,255,255,0,5,0,0,0,4,255,255,0,1,0,0,0,2,123,123,123,
        22,200,200,200,1,123,123,0,5,255,255,0,5,0,0,0,4,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,21,200,200,200,
        1,123,123,0,5,255,255,0,5,0,0,0,5,255,255,0,1,0,0,0,2,123,123,123,20,200,200,200,1,123,123,0,6,255,255,0,5,0,0,
        0,5,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,19,200,200,200,1,123,123,0,6,255,255,0,1,123,123,0,3,0,0,0,1,
        123,123,0,6,255,255,0,1,0,0,0,2,123,123,123,18,200,200,200,1,123,123,0,7,255,255,0,1,189,189,189,3,0,0,0,1,189,
        189,189,6,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,17,200,200,200,1,123,123,0,8,255,255,0,3,0,0,0,8,255,
        255,0,1,0,0,0,2,123,123,123,16,200,200,200,1,123,123,0,9,255,255,0,1,123,123,0,1,0,0,0,1,123,123,0,8,255,255,0,
        1,189,189,189,1,0,0,0,2,123,123,123,15,200,200,200,1,123,123,0,9,255,255,0,1,189,189,189,1,0,0,0,1,189,189,189,
        9,255,255,0,1,0,0,0,2,123,123,123,14,200,200,200,1,123,123,0,11,255,255,0,1,0,0,0,10,255,255,0,1,189,189,189,1,
        0,0,0,2,123,123,123,13,200,200,200,1,123,123,0,23,255,255,0,1,0,0,0,2,123,123,123,12,200,200,200,1,123,123,0,11,
        255,255,0,1,189,189,189,2,0,0,0,1,189,189,189,9,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,11,200,200,200,1,
        123,123,0,11,255,255,0,4,0,0,0,10,255,255,0,1,0,0,0,2,123,123,123,10,200,200,200,1,123,123,0,12,255,255,0,4,0,0,
        0,10,255,255,0,1,189,189,189,1,0,0,0,2,123,123,123,9,200,200,200,1,123,123,0,12,255,255,0,1,189,189,189,2,0,0,0,
        1,189,189,189,11,255,255,0,1,0,0,0,2,123,123,123,9,200,200,200,1,123,123,0,27,255,255,0,1,0,0,0,3,123,123,123,8,
        200,200,200,1,123,123,0,26,255,255,0,1,189,189,189,1,0,0,0,3,123,123,123,9,200,200,200,1,123,123,0,24,255,255,0,
        1,189,189,189,1,0,0,0,4,123,123,123,10,200,200,200,1,123,123,0,24,0,0,0,5,123,123,123,12,200,200,200,27,123,123,
        123,14,200,200,200,25,123,123,123,86,200,200,200,91,49,124,118,124,71,32,124,95,49,56,114,52,82,121,0 };
      return data;
    }

    // Define a 256 array, used in _cimg_math_parser to fast-check if operator tests can be skipped.
    // In this array, all values are set to 0 except for characters "=+*-/^<>&|?~!%" (set to 1).
    static const char _cimg_math_parser_check_operator[] = {
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    //! Get/set default output stream for the \CImg library messages.
    /**
       \param file Desired output stream. Set to \c 0 to get the currently used output stream only.
       \return Currently used output stream.
    **/
    inline std::FILE* output(std::FILE *file) {
      cimg::mutex(1);
      static std::FILE *res = cimg::_stderr();
      if (file) res = file;
      cimg::mutex(1,0);
      return res;
    }

    // Return number of available CPU cores.
    inline unsigned int nb_cpus() {
      unsigned int res = 1;
#if cimg_OS==2
      SYSTEM_INFO sysinfo;
      GetSystemInfo(&sysinfo);
      res = (unsigned int)sysinfo.dwNumberOfProcessors;
#elif cimg_OS==1
      res = (unsigned int)sysconf(_SC_NPROCESSORS_ONLN);
#endif
      return res?res:1U;
    }

    // Lock/unlock mutex for CImg multi-thread programming.
    inline int mutex(const unsigned int n, const int lock_mode) {
      switch (lock_mode) {
      case 0 : cimg::Mutex_attr::ref().unlock(n); return 0;
      case 1 : cimg::Mutex_attr::ref().lock(n); return 0;
      default : return cimg::Mutex_attr::ref().trylock(n);
      }
    }

    // Display a warning message on the default output stream.
    inline void warn(const char *const format, ...);

    // Execute an external system command.
    /**
       \param command C-string containing the command line to execute.
       \param module_name Module name.
       \param is_verbose Indicates whether the command output should be silent or verbose.
       \return Status value of the executed command, whose meaning is OS-dependent.
       \note This function is similar to <tt>std::system()</tt>
       but it does not open an extra console windows
       on Windows-based systems.
    **/
    inline int system(const char *const command, const char *const module_name=0, const bool is_verbose=false) {
      cimg::unused(module_name);
#ifdef cimg_no_system_calls
      cimg::unused(command,is_verbose);
      return -1;
#else

      if (is_verbose) return std::system(command);
#if cimg_OS==1
      const unsigned int l = (unsigned int)std::strlen(command);
      if (l) {
        char *const ncommand = new char[l + 24];
        std::memcpy(ncommand,command,l);
        std::strcpy(ncommand + l," >/dev/null 2>&1"); // Make command silent
        const int out_val = std::system(ncommand);
        delete[] ncommand;
        return out_val;
      } else return -1;
#elif cimg_OS==2
      const unsigned int l = (unsigned int)std::strlen(command);
      if (l) {
        char *const ncommand = new char[l + 1];
        std::strcpy(ncommand,command);
        PROCESS_INFORMATION pi;
        STARTUPINFOA si;
        std::memset(&pi,0,sizeof(PROCESS_INFORMATION));
        std::memset(&si,0,sizeof(STARTUPINFO));
        GetStartupInfoA(&si);
        si.cb = sizeof(si);
        si.wShowWindow = SW_HIDE;
        si.dwFlags|=STARTF_USESHOWWINDOW;
        const BOOL res = CreateProcessA((LPCSTR)module_name,ncommand,0,0,FALSE,0,0,0,&si,&pi);
        delete[] ncommand;
        if (res) {
          WaitForSingleObject(pi.hProcess,INFINITE);
          DWORD exitCode = 0;
          if (!GetExitCodeProcess(pi.hProcess,&exitCode)) exitCode = (DWORD)-1;
          CloseHandle(pi.hThread);
          CloseHandle(pi.hProcess);
          return (int)exitCode;
        } else {
          char* lpMsgBuf;

          // Get the error message.
          DWORD errorCode = GetLastError();
          FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                         0,errorCode,MAKELANGID(LANG_NEUTRAL,SUBLANG_DEFAULT),(LPSTR)&lpMsgBuf,0,0);
          cimg::warn("cimg::system() : Command '%s' (module name '%s) failed with error %lu: %s",
                     command==0?"(null)":command,
                     module_name==0?"(null)":module_name,
                     errorCode,lpMsgBuf);

          if (lpMsgBuf) LocalFree(lpMsgBuf);
          return -1;
        }
      } else return -1;
#else
      return std::system(command);
#endif
#endif
    }

    //! Return a reference to a temporary variable of type T.
    template<typename T>
    inline T& temporary(const T&) {
      static T temp;
      return temp;
    }

    //! Exchange values of variables \c a and \c b.
    template<typename T>
    inline void swap(T& a, T& b) {
      std::swap(a,b);
    }

    //! Exchange values of variables (\c a1,\c a2) and (\c b1,\c b2).
    template<typename T1, typename T2>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2) {
      cimg::swap(a1,b1); cimg::swap(a2,b2);
    }

    //! Exchange values of variables (\c a1,\c a2,\c a3) and (\c b1,\c b2,\c b3).
    template<typename T1, typename T2, typename T3>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3) {
      cimg::swap(a1,b1,a2,b2); cimg::swap(a3,b3);
    }

    //! Exchange values of variables (\c a1,\c a2,...,\c a4) and (\c b1,\c b2,...,\c b4).
    template<typename T1, typename T2, typename T3, typename T4>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3, T4& a4, T4& b4) {
      cimg::swap(a1,b1,a2,b2,a3,b3); cimg::swap(a4,b4);
    }

    //! Exchange values of variables (\c a1,\c a2,...,\c a5) and (\c b1,\c b2,...,\c b5).
    template<typename T1, typename T2, typename T3, typename T4, typename T5>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3, T4& a4, T4& b4, T5& a5, T5& b5) {
      cimg::swap(a1,b1,a2,b2,a3,b3,a4,b4); cimg::swap(a5,b5);
    }

    //! Exchange values of variables (\c a1,\c a2,...,\c a6) and (\c b1,\c b2,...,\c b6).
    template<typename T1, typename T2, typename T3, typename T4, typename T5, typename T6>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3, T4& a4, T4& b4, T5& a5, T5& b5, T6& a6, T6& b6) {
      cimg::swap(a1,b1,a2,b2,a3,b3,a4,b4,a5,b5); cimg::swap(a6,b6);
    }

    //! Exchange values of variables (\c a1,\c a2,...,\c a7) and (\c b1,\c b2,...,\c b7).
    template<typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3, T4& a4, T4& b4, T5& a5, T5& b5, T6& a6, T6& b6,
                     T7& a7, T7& b7) {
      cimg::swap(a1,b1,a2,b2,a3,b3,a4,b4,a5,b5,a6,b6); cimg::swap(a7,b7);
    }

    //! Exchange values of variables (\c a1,\c a2,...,\c a8) and (\c b1,\c b2,...,\c b8).
    template<typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8>
    inline void swap(T1& a1, T1& b1, T2& a2, T2& b2, T3& a3, T3& b3, T4& a4, T4& b4, T5& a5, T5& b5, T6& a6, T6& b6,
                     T7& a7, T7& b7, T8& a8, T8& b8) {
      cimg::swap(a1,b1,a2,b2,a3,b3,a4,b4,a5,b5,a6,b6,a7,b7); cimg::swap(a8,b8);
    }

    //! Return the endianness of the current architecture.
    /**
       \return \c false for <i>Little Endian</i> or \c true for <i>Big Endian</i>.
    **/
    inline bool endianness() {
      const int x = 1;
      return ((unsigned char*)&x)[0]?false:true;
    }

    //! Reverse endianness of all elements in a memory buffer.
    /**
       \param[in,out] buffer Memory buffer whose endianness must be reversed.
       \param size Number of buffer elements to reverse.
    **/
    template<typename T>
    inline void invert_endianness(T* const buffer, const cimg_ulong size) {
      if (size) switch (sizeof(T)) {
        case 1 : break;
        case 2 : {
          for (unsigned short *ptr = (unsigned short*)buffer + size; ptr>(unsigned short*)buffer; ) {
            const unsigned short val = *(--ptr);
            *ptr = (unsigned short)((val>>8) | ((val<<8)));
          }
        } break;
        case 4 : {
          for (unsigned int *ptr = (unsigned int*)buffer + size; ptr>(unsigned int*)buffer; ) {
            const unsigned int val = *(--ptr);
            *ptr = (val>>24) | ((val>>8)&0xff00) | ((val<<8)&0xff0000) | (val<<24);
          }
        } break;
        case 8 : {
          const cimg_uint64
            m0 = (cimg_uint64)0xff, m1 = m0<<8, m2 = m0<<16, m3 = m0<<24,
            m4 = m0<<32, m5 = m0<<40, m6 = m0<<48, m7 = m0<<56;
          for (cimg_uint64 *ptr = (cimg_uint64*)buffer + size; ptr>(cimg_uint64*)buffer; ) {
            const cimg_uint64 val = *(--ptr);
            *ptr =  (((val&m7)>>56) | ((val&m6)>>40) | ((val&m5)>>24) | ((val&m4)>>8) |
                     ((val&m3)<<8) |((val&m2)<<24) | ((val&m1)<<40) | ((val&m0)<<56));
          }
        } break;
        default : {
          for (T* ptr = buffer + size; ptr>buffer; ) {
            unsigned char *pb = (unsigned char*)(--ptr), *pe = pb + sizeof(T);
            for (int i = 0; i<(int)sizeof(T)/2; ++i) swap(*(pb++),*(--pe));
          }
        }
        }
    }
    inline void invert_endianness(bool* const, const cimg_ulong) {}
    inline void invert_endianness(unsigned char* const, const cimg_ulong) {}
    inline void invert_endianness(char* const, const cimg_ulong) {}

    //! Reverse endianness of a single variable.
    /**
       \param[in,out] a Variable to reverse.
       \return Reference to reversed variable.
    **/
    template<typename T>
    inline T& invert_endianness(T& a) {
      invert_endianness(&a,1);
      return a;
    }

    // Conversion functions to get more precision when trying to store 'unsigned int' values as 'float'.
    template<typename T>
    inline T uint2float(const unsigned int value, T) { // T is typically 'float' or 'float16'
      if (cimg::type<T>::string()==cimg::type<float>::string()) { // float32 version
        const unsigned int th = 1U<<24; // Consider 'float32' can safely store 'uint32' until 16777216
        if (value<th) return (float)value;
        float f;
        const unsigned int v = (value - th) | 0xC0000000; // Offset + set sign & first exponent bit to 1
        // use memcpy instead of simple assignment to avoid undesired optimizations by C++-compiler.
        std::memcpy(&f,&v,sizeof(float));
        return (T)f;
      }
#if cimg_is_float16
      else if (cimg::type<T>::string()==cimg::type<cimg_float16>::string()) { // float16 version
        const unsigned short th = 1U<<11; // Consider 'float16' can safely store 'uint16' until 2048
        if (value<th) return (float)value;
        cimg_float16 f;
        const unsigned short v = (value - th) | 0xC000; // Offset + set sign & first exponent bit to 1
        // use memcpy instead of simple assignment to avoid undesired optimizations by C++-compiler.
        std::memcpy((unsigned short*)&f,&v,sizeof(unsigned short));
        return (T)f;
      }
#endif
      return (unsigned int)value;
    }

    inline unsigned int float2uint(const float value) {
      const unsigned int th = 1U<<24; // Consider 'float32' can safely store 'uint32' until 16777216
      int tmp = 0;
      std::memcpy(&tmp,&value,sizeof(int));
      if (tmp>=0) return (unsigned int)value;
      unsigned int u;
      // use memcpy instead of assignment to avoid undesired optimizations by C++-compiler.
      std::memcpy(&u,&value,sizeof(unsigned int));
      return (u&0x3FFFFFFF) + th;
    }

#if cimg_is_float16
    inline unsigned int float2uint(const cimg_float16 value) {
      const unsigned short th = 1U<<11; // Consider 'float16' can safely store 'uint16' until 2048
      short tmp = 0;
      std::memcpy(&tmp,&value,sizeof(short));
      if (tmp>=0) return (unsigned short)value;
      unsigned short u;
      // use memcpy instead of assignment to avoid undesired optimizations by C++-compiler.
      std::memcpy(&u,&value,sizeof(unsigned short));
      return (u&0x3FFF) + th;
    }
#endif

    //! Return the value of a system timer, with a millisecond precision.
    /**
       Note: The timer does not necessarily start from \c 0.
    **/
    inline cimg_uint64 time() {
#if cimg_OS==1
      struct timeval st_time;
      gettimeofday(&st_time,0);
      return (cimg_uint64)st_time.tv_sec*1000 + (cimg_uint64)st_time.tv_usec/1000;
#elif cimg_OS==2
      ULARGE_INTEGER ul;
      FILETIME ft;
      GetSystemTimeAsFileTime(&ft);
      ul.LowPart = ft.dwLowDateTime;
      ul.HighPart = ft.dwHighDateTime;
      return (cimg_uint64)ul.QuadPart/10000;
#else
      return 0;
#endif
    }

    // Implement a tic/toc mechanism to display elapsed time of algorithms.
    inline cimg_uint64 tictoc(const bool is_tic);

    //! Start tic/toc timer for time measurement between code instructions.
    /**
       \return Current value of the timer (same value as time()).
    **/
    inline cimg_uint64 tic() {
      return cimg::tictoc(true);
    }

    //! End tic/toc timer and displays elapsed time from last call to tic().
    /**
       \return Time elapsed (in ms) since last call to tic().
    **/
    inline cimg_uint64 toc() {
      return cimg::tictoc(false);
    }

    //! Sleep for a given numbers of milliseconds.
    /**
       \param milliseconds Number of milliseconds to wait for.
       \note This function frees the CPU resources during the sleeping time.
       It can be used to pace your program properly, without wasting CPU time.
    **/
    inline void sleep(const unsigned int milliseconds) {
#if cimg_OS==1
      struct timespec tv;
      tv.tv_sec = milliseconds/1000;
      tv.tv_nsec = (milliseconds%1000)*1000000;
      nanosleep(&tv,0);
#elif cimg_OS==2
      Sleep(milliseconds);
#else
      cimg::unused(milliseconds);
#endif
    }

    inline unsigned int wait(const unsigned int milliseconds, cimg_uint64 *const p_timer) {
      if (!*p_timer) *p_timer = cimg::time();
      const cimg_uint64 current_time = cimg::time();
      if (current_time<*p_timer || current_time>=*p_timer + milliseconds) { *p_timer = current_time; return 0; }
      const unsigned int time_diff = (unsigned int)(*p_timer + milliseconds - current_time);
      *p_timer = current_time + time_diff;
      cimg::sleep(time_diff);
      return time_diff;
    }

    //! Wait for a given number of milliseconds since the last call to wait().
    /**
       \param milliseconds Number of milliseconds to wait for.
       \return Number of milliseconds elapsed since the last call to wait().
       \note Same as sleep() with a waiting time computed with regard to the last call
       of wait(). It may be used to temporize your program properly, without wasting CPU time.
    **/
    inline unsigned int wait(const unsigned int milliseconds) {
      cimg::mutex(3);
      static cimg_uint64 timer = cimg::time();
      cimg::mutex(3,0);
      return cimg::wait(milliseconds,&timer);
    }

    //! Cut (i.e. clamp) value in specified interval.
    template<typename T>
    inline T cut(const T& val, const T& val_min, const T& val_max) {
      return val<=val_min?val_min:val>=val_max?val_max:val;
    }

    // Custom random number generator (allow re-entrance).
    inline cimg_uint64& rng() { // Used as a shared global number for rng
      static cimg_uint64 rng = 0xB16B00B5U;
      return rng;
    }

    inline unsigned int _rand(cimg_uint64 *const p_rng) {
      cimg_uint64 x = *p_rng;
      x^=x<<13; x^=x>>7; x^=x<<17;
      *p_rng = x?x:1;
      return (unsigned int)((x*(cimg_uint64)0x9E3779B9U)>>32);
    }

    inline unsigned int _rand() {
      cimg::mutex(4);
      const unsigned int res = cimg::_rand(&cimg::rng());
      cimg::mutex(4,0);
      return res;
    }

    inline void srand(cimg_uint64 *const p_rng) {
      if (p_rng) {
#if cimg_OS==1 || defined(__BORLANDC__)
        *p_rng = cimg::time() + (cimg_uint64)getpid();
#elif cimg_OS==2
        *p_rng = cimg::time() + (cimg_uint64)_getpid();
#else
        *p_rng = (cimg_uint64)std::time(0);
#endif
      }
    }

    inline void srand() {
      cimg::mutex(4);
      cimg::srand(&cimg::rng());
      cimg::mutex(4,0);
    }

    inline void srand(const cimg_uint64 seed) {
      cimg::mutex(4);
      cimg::rng() = seed;
      cimg::mutex(4,0);
    }

    inline double rand(const double val_min, const double val_max, cimg_uint64 *const p_rng) {
      return val_min + (val_max - val_min)*cimg::_rand(p_rng)/~0U;
    }

    inline double rand(const double val_min, const double val_max) {
      cimg::mutex(4);
      const double res = cimg::rand(val_min,val_max,&cimg::rng());
      cimg::mutex(4,0);
      return res;
    }

    inline double rand(const double val_max, cimg_uint64 *const p_rng) {
      return val_max*cimg::_rand(p_rng)/(double)~0U;
    }

    inline double rand(const double val_max=1) {
      cimg::mutex(4);
      const double res = cimg::rand(val_max,&cimg::rng());
      cimg::mutex(4,0);
      return res;
    }

    inline double grand(cimg_uint64 *const p_rng) {
      double x1, w;
      do {
        const double x2 = cimg::rand(-1,1,p_rng);
        x1 = cimg::rand(-1,1,p_rng);
        w = x1*x1 + x2*x2;
      } while (w<=0 || w>=1.);
      return x1*std::sqrt((-2*std::log(w))/w);
    }

    inline double grand() {
      cimg::mutex(4);
      const double res = cimg::grand(&cimg::rng());
      cimg::mutex(4,0);
      return res;
    }

    inline unsigned int prand(const double z, cimg_uint64 *const p_rng) {
      if (z<=1.e-10) return 0;
      if (z>100) return (unsigned int)cimg::cut(std::sqrt(z)*cimg::grand(p_rng) + z,
                                                0.,(double)cimg::type<unsigned int>::max());
      unsigned int k = 0;
      const double y = std::exp(-z);
      for (double s = 1.; s>=y; ++k) s*=cimg::rand(1,p_rng);
      return k - 1;
    }

    inline unsigned int prand(const double z) {
      cimg::mutex(4);
      const unsigned int res = cimg::prand(z,&cimg::rng());
      cimg::mutex(4,0);
      return res;
    }

    //! Bitwise shift value to the left (safeguarded against overflow).
    template<typename T>
    inline T bsl(const T& a, const int n=1) {
      return (n<0 || n>=(int)(sizeof(T)<<3))?(T)0:(T)(a<<n);
    }

    inline float bsl(const float a, const int n=1) {
      return (float)bsl((int)a,n);
    }

    inline double bsl(const double a, const int n=1) {
      return (double)bsl((cimg_long)a,n);
    }

    inline double bsl(const long double a, const int n=1) {
      return (double)bsl((cimg_long)a,n);
    }

#if cimg_is_float16==1
    inline cimg_float16 bsl(const cimg_float16 a, const int n=1) {
      return (cimg_float16)bsl((int)a,n);
    }
#endif

    //! Bitwise shift value to the right (safeguarded against overflow).
    template<typename T>
    inline T bsr(const T& a, const int n=1) {
      return (n<0 || n>=(int)(sizeof(T)<<3))?(T)0:(T)(a>>n);
    }

    inline float bsr(const float a, const int n=1) {
      return (float)bsr((int)a,n);
    }

    inline double bsr(const double a, const int n=1) {
      return (double)bsr((cimg_long)a,n);
    }

    inline double bsr(const long double a, const int n=1) {
      return (double)bsr((cimg_long)a,n);
    }

#if cimg_is_float16==1
    inline cimg_float16 bsr(const cimg_float16 a, const int n=1) {
      return (cimg_float16)bsr((int)a,n);
    }
#endif

    //! Bitwise-rotate value on the left.
    template<typename T>
    inline T rol(const T& a, const unsigned int n=1) {
      return n?(T)((a<<n)|(a>>((sizeof(T)<<3) - n))):a;
    }

    inline float rol(const float a, const unsigned int n=1) {
      return (float)rol((int)a,n);
    }

    inline double rol(const double a, const unsigned int n=1) {
      return (double)rol((cimg_long)a,n);
    }

    inline double rol(const long double a, const unsigned int n=1) {
      return (double)rol((cimg_long)a,n);
    }

#if cimg_is_float16==1
    inline cimg_float16 rol(const cimg_float16 a, const unsigned int n=1) {
      return (cimg_float16)rol((int)a,n);
    }
#endif

    //! Bitwise-rotate value on the right.
    template<typename T>
    inline T ror(const T& a, const unsigned int n=1) {
      return n?(T)((a>>n)|(a<<((sizeof(T)<<3) - n))):a;
    }

    inline float ror(const float a, const unsigned int n=1) {
      return (float)ror((int)a,n);
    }

    inline double ror(const double a, const unsigned int n=1) {
      return (double)ror((cimg_long)a,n);
    }

    inline double ror(const long double a, const unsigned int n=1) {
      return (double)ror((cimg_long)a,n);
    }

#if cimg_is_float16==1
    inline cimg_float16 ror(const cimg_float16 a, const unsigned int n=1) {
      return (cimg_float16)ror((int)a,n);
    }
#endif

    //! Return absolute value of a value.
    template<typename T>
    inline T abs(const T& a) {
      return a>=0?a:-a;
    }
    inline bool abs(const bool a) {
      return a;
    }
    inline int abs(const unsigned char a) {
      return (int)a;
    }
    inline int abs(const unsigned short a) {
      return (int)a;
    }
    inline int abs(const unsigned int a) {
      return (int)a;
    }
    inline int abs(const int a) {
      return std::abs(a);
    }
    inline cimg_int64 abs(const cimg_uint64 a) {
      const cimg_uint64 max_signed = (cimg_uint64)cimg::type<cimg_int64>::max();
      return a<max_signed?(cimg_int64)a:cimg::type<cimg_int64>::max();
    }
    inline double abs(const double a) {
      return std::fabs(a);
    }
    inline float abs(const float a) {
      return std::fabs(a);
    }

    //! Return fractional part of a value.
    template<typename T>
    inline T frac(const T x) {
      return x - std::floor(x);
    }

    //! Return hyperbolic arcosine of a value.
    inline double acosh(const double x) {
#if cimg_use_cpp11==1 && !defined(_MSC_VER)
      return std::acosh(x);
#else
      return std::log(x + std::sqrt(x*x - 1));
#endif
    }

    //! Return hyperbolic arcsine of a value.
    inline double asinh(const double x) {
#if cimg_use_cpp11==1 && !defined(_MSC_VER)
      return std::asinh(x);
#else
      return std::log(x + std::sqrt(x*x + 1));
#endif
    }

    //! Return hyperbolic arctangent of a value.
    inline double atanh(const double x) {
#if cimg_use_cpp11==1 && !defined(_MSC_VER)
      return std::atanh(x);
#else
      return 0.5*std::log((1. + x)/(1. - x));
#endif
    }

    //! Return the sinc of a given value.
    inline double sinc(const double x) {
      return x?std::sin(x)/x:1;
    }

    //! Return base-2 logarithm of a value.
    inline double log2(const double x) {
#if cimg_use_cpp11==1 && !defined(_MSC_VER)
      return std::log2(x);
#else
      const double base2 = std::log(2.);
      return std::log(x)/base2;
#endif
    }

    //! Return square of a value.
    template<typename T>
    inline T sqr(const T& val) {
      return val*val;
    }

    // Return inverse of error function.
    template<typename T>
    inline T erfinv(const T& val) {
      const T
        sgn = val<0?-1:1,
        x = (1 - val)*(1 + val),
        lnx = std::log(x),
        tt1 = (T)(2/(cimg::PI*0.147) + 0.5*lnx),
        tt2 = lnx/(T)0.147;
      return sgn*std::sqrt(-tt1 + std::sqrt(tt1*tt1 - tt2));
    }

    //! Return cubic root of a value.
    template<typename T>
    inline double cbrt(const T& x) {
#if cimg_use_cpp11==1
      return std::cbrt(x);
#else
      return x>=0?std::pow((double)x,1./3):-std::pow(-(double)x,1./3);
#endif
    }

    template<typename T>
    inline T pow3(const T& val) {
      return val*val*val;
    }
    template<typename T>
    inline T pow4(const T& val) {
      return val*val*val*val;
    }

    //! Return the minimum between three values.
    template<typename t>
    inline t min(const t& a, const t& b, const t& c) {
      return std::min(std::min(a,b),c);
    }

    //! Return the minimum between four values.
    template<typename t>
    inline t min(const t& a, const t& b, const t& c, const t& d) {
      return std::min(std::min(a,b),std::min(c,d));
    }

    //! Return the minabs between two values.
    template<typename t>
    inline t minabs(const t& a, const t& b) {
      return cimg::abs(b)<cimg::abs(a)?b:a;
    }

    template<typename t>
    inline t minabs(const t& a, const t& b, const t& abs_b) {
      typedef typename cimg::superset<t,int>::type tint;
      return (tint)abs_b<(tint)cimg::abs(a)?b:a;
    }

    //! Return the maximum between three values.
    template<typename t>
    inline t max(const t& a, const t& b, const t& c) {
      return std::max(std::max(a,b),c);
    }

    //! Return the maximum between four values.
    template<typename t>
    inline t max(const t& a, const t& b, const t& c, const t& d) {
      return std::max(std::max(a,b),std::max(c,d));
    }

    //! Return the maxabs between two values.
    template<typename t>
    inline t maxabs(const t& a, const t& b) {
      return cimg::abs(b)>cimg::abs(a)?b:a;
    }

    template<typename t>
    inline t maxabs(const t& a, const t& b, const t& abs_b) {
      typedef typename cimg::superset<t,int>::type tint;
      return (tint)abs_b>(tint)cimg::abs(a)?b:a;
    }

    //! Return the sigmoid of a value.
    template<typename T>
    inline T sigmoid(const T& x) {
      return (T)((1 + std::tanh(x/2))/2);
    }

    //! Return the logit of a value.
    template<typename T>
    inline T logit(const T& x) {
      return (T)std::log(x/(1. - x));
    }

    // Convert radians to degrees.
    template<typename T>
    inline T rad2deg(const T& x) {
      return (T)(x*180/cimg::PI);
    }

    // Convert degrees to radians.
    template<typename T>
    inline T deg2rad(const T& x) {
      return (T)(x*cimg::PI/180);
    }

    //! Return the sign of a value.
    template<typename T>
    inline T sign(const T& x) {
      return (T)(cimg::type<T>::is_nan(x)?0:x<0?-1:x>0);
    }

    //! Cut (i.e. clamp) absolute value in specified interval.
    template<typename T>
    inline T abscut(const T& val, const T& val_min, const T& val_max, const T& offset) {
      typedef typename cimg::superset<T,int>::type Tint;
      const T sgn = cimg::sign(val);
      return (T)cimg::cut((Tint)(val*sgn + offset),(Tint)val_min,(Tint)val_max)*sgn;
    }

    //! Return the nearest power of 2 higher than given value.
    template<typename T>
    inline cimg_uint64 nearest_pow2(const T& x) {
      cimg_uint64 i = 1;
      const cimg_uint64 max_pow2 = (cimg_uint64)1<<(sizeof(cimg_uint64)*8 - 1);
      while (x>i && i<max_pow2) i<<=1;
      return i;
    }

    //! Return the modulo of a value.
    /**
       \param x Input value.
       \param m Modulo value.
       \note This modulo function accepts negative and floating-points modulo numbers, as well as variables of any type.
    **/
    template<typename T>
    inline T mod(const T& x, const T& m) {
      if (!m) {
        if (cimg::type<T>::is_float()) return cimg::type<T>::nan();
        else throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      }
      const double dx = (double)x, dm = (double)m;
      if (!cimg::type<double>::is_finite(dm)) return x;
      if (cimg::type<double>::is_finite(dx)) return (T)(dx - dm * std::floor(dx / dm));
      return (T)0;
    }
    inline int mod(const bool x, const bool m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return x?1:0;
    }
    inline int mod(const unsigned char x, const unsigned char m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return x%m;
    }
    inline int mod(const char x, const char m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
#if defined(CHAR_MAX) && CHAR_MAX==255
      return x%m;
#else
      return x>=0?x%m:(x%m?m + x%m:0);
#endif
    }
    inline int mod(const unsigned short x, const unsigned short m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (int)(x%m);
    }
    inline int mod(const short x, const short m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (int)(x>=0?x%m:(x%m?m + x%m:0));
    }
    inline int mod(const unsigned int x, const unsigned int m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (int)(x%m);
    }
    inline int mod(const int x, const int m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (int)(x>=0?x%m:(x%m?m + x%m:0));
    }
    inline cimg_int64 mod(const cimg_uint64 x, const cimg_uint64 m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (cimg_int64)(x%m);
    }
    inline cimg_int64 mod(const cimg_int64 x, const cimg_int64 m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return (cimg_int64)(x>=0?x%m:(x%m?m + x%m:0));
    }

    //! Return the min-mod of two values.
    /**
       \note <i>minmod(\p a,\p b)</i> is defined to be:
       - <i>minmod(\p a,\p b) = min(\p a,\p b)</i>, if \p a and \p b have the same sign.
       - <i>minmod(\p a,\p b) = 0</i>, if \p a and \p b have different signs.
    **/
    template<typename T>
    inline T minmod(const T& a, const T& b) {
      return a*b<=0?0:(a>0?(a<b?a:b):(a<b?b:a));
    }

    template<typename T>
    inline T round(const T& x) {
      return (T)(cimg_int64)(x>=0?x + 0.5f:x - 0.5f);
    }

    template<typename T>
    inline int uiround(const T x) {
      return cimg::type<T>::is_float()?(int)(x + 0.5f):(int)x;
    }

    // Return 'round(a/b)' where 'a' and 'b>0' are integers. 'hb' must be equal to 'b/2' ("half b").
    // Particularity: When the fractional part of 'a/b' is 0.5, the rounding depends on the sign of 'a':
    // - If a>0, 'round_div(a/b) = ceil(a/b)'.
    // - If a<0, 'round_div(a.b) = floor(a/b)'.
    // (so, this is **not** a classical rounding behavior!).
    // This function is used by drawing functions, to get coherent rounded primitive coordinates.
    // Beware, 'b' must be strictly positive!
    template<typename T, typename t>
    t inline round_div(const T a, const t b, const t hb) {
      return (t)(b==1?a:a>=0?(a + hb)/b:-(hb - 1 - a)/b);
    }
#define cimg_rd(a,b,c) cimg::round_div((cimg_long)a*b,c,h##c)

    //! Return rounded value.
    /**
       \param x Value to be rounded.
       \param y Rounding precision.
       \param rounding_type Type of rounding operation (\c 0 = nearest, \c -1 = backward, \c 1 = forward).
       \return Rounded value, having the same type as input value \c x.
    **/
    template<typename T>
    inline T round(const T& x, const double y, const int rounding_type=0) {
      if (y<=0) return x;
      if (y==1) switch (rounding_type) {
        case 0 : return cimg::round(x);
        case 1 : return (T)std::ceil((_cimg_Tfloat)x);
        default : return (T)std::floor((_cimg_Tfloat)x);
        }
      const double sx = (double)x/y, floor = std::floor(sx), delta =  sx - floor;
      return (T)(y*(rounding_type<0?floor:rounding_type>0?std::ceil(sx):delta<0.5?floor:std::ceil(sx)));
    }

    // Code to compute fast median from 2,3,5,7,9,13,25 and 49 values.
    // (contribution by RawTherapee: http://rawtherapee.com/).
    template<typename T>
    inline T median(T val0, T val1) {
      return (val0 + val1)/2;
    }

    template<typename T>
    inline T median(T val0, T val1, T val2) {
      return std::max(std::min(val0,val1),std::min(val2,std::max(val0,val1)));
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3) {
      const T
        tmp0 = cimg::min(val0,val1,val2,val3),
        tmp1 = cimg::max(val0,val1,val2,val3);
      return (val0 + val1 + val2 + val3 - tmp0 - tmp1)/2;
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4) {
      T tmp = std::min(val0,val1);
      val1 = std::max(val0,val1); val0 = tmp; tmp = std::min(val3,val4); val4 = std::max(val3,val4);
      val3 = std::max(val0,tmp);  val1 = std::min(val1,val4); tmp = std::min(val1,val2); val2 = std::max(val1,val2);
      val1 = tmp; tmp = std::min(val2,val3);
      return std::max(val1,tmp);
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4, T val5, T val6) {
      T tmp = std::min(val0,val5);
      val5 = std::max(val0,val5); val0 = tmp; tmp = std::min(val0,val3); val3 = std::max(val0,val3); val0 = tmp;
      tmp = std::min(val1,val6); val6 = std::max(val1,val6); val1 = tmp; tmp = std::min(val2,val4);
      val4 = std::max(val2,val4); val2 = tmp; val1 = std::max(val0,val1); tmp = std::min(val3,val5);
      val5 = std::max(val3,val5); val3 = tmp; tmp = std::min(val2,val6); val6 = std::max(val2,val6);
      val3 = std::max(tmp,val3); val3 = std::min(val3,val6); tmp = std::min(val4,val5); val4 = std::max(val1,tmp);
      tmp = std::min(val1,tmp); val3 = std::max(tmp,val3);
      return std::min(val3,val4);
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4, T val5, T val6, T val7, T val8) {
      T tmp = std::min(val1,val2);
      val2 = std::max(val1,val2); val1 = tmp; tmp = std::min(val4,val5);
      val5 = std::max(val4,val5); val4 = tmp; tmp = std::min(val7,val8);
      val8 = std::max(val7,val8); val7 = tmp; tmp = std::min(val0,val1);
      val1 = std::max(val0,val1); val0 = tmp; tmp = std::min(val3,val4);
      val4 = std::max(val3,val4); val3 = tmp; tmp = std::min(val6,val7);
      val7 = std::max(val6,val7); val6 = tmp; tmp = std::min(val1,val2);
      val2 = std::max(val1,val2); val1 = tmp; tmp = std::min(val4,val5);
      val5 = std::max(val4,val5); val4 = tmp; tmp = std::min(val7,val8);
      val8 = std::max(val7,val8); val3 = std::max(val0,val3); val5 = std::min(val5,val8);
      val7 = std::max(val4,tmp); tmp = std::min(val4,tmp); val6 = std::max(val3,val6);
      val4 = std::max(val1,tmp); val2 = std::min(val2,val5); val4 = std::min(val4,val7);
      tmp = std::min(val4,val2); val2 = std::max(val4,val2); val4 = std::max(val6,tmp);
      return std::min(val4,val2);
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4, T val5, T val6, T val7, T val8, T val9, T val10, T val11,
                    T val12) {
      T tmp = std::min(val1,val7);
      val7 = std::max(val1,val7); val1 = tmp; tmp = std::min(val9,val11); val11 = std::max(val9,val11); val9 = tmp;
      tmp = std::min(val3,val4);  val4 = std::max(val3,val4); val3 = tmp; tmp = std::min(val5,val8);
      val8 = std::max(val5,val8); val5 = tmp; tmp = std::min(val0,val12); val12 = std::max(val0,val12);
      val0 = tmp; tmp = std::min(val2,val6); val6 = std::max(val2,val6); val2 = tmp; tmp = std::min(val0,val1);
      val1 = std::max(val0,val1); val0 = tmp; tmp = std::min(val2,val3); val3 = std::max(val2,val3); val2 = tmp;
      tmp = std::min(val4,val6);  val6 = std::max(val4,val6); val4 = tmp; tmp = std::min(val8,val11);
      val11 = std::max(val8,val11); val8 = tmp; tmp = std::min(val7,val12); val12 = std::max(val7,val12); val7 = tmp;
      tmp = std::min(val5,val9); val9 = std::max(val5,val9); val5 = tmp; tmp = std::min(val0,val2);
      val2 = std::max(val0,val2); val0 = tmp; tmp = std::min(val3,val7); val7 = std::max(val3,val7); val3 = tmp;
      tmp = std::min(val10,val11); val11 = std::max(val10,val11); val10 = tmp; tmp = std::min(val1,val4);
      val4 = std::max(val1,val4); val1 = tmp; tmp = std::min(val6,val12); val12 = std::max(val6,val12); val6 = tmp;
      tmp = std::min(val7,val8); val8 = std::max(val7,val8); val7 = tmp; val11 = std::min(val11,val12);
      tmp = std::min(val4,val9); val9 = std::max(val4,val9); val4 = tmp; tmp = std::min(val6,val10);
      val10 = std::max(val6,val10); val6 = tmp; tmp = std::min(val3,val4); val4 = std::max(val3,val4); val3 = tmp;
      tmp = std::min(val5,val6); val6 = std::max(val5,val6); val5 = tmp; val8 = std::min(val8,val9);
      val10 = std::min(val10,val11); tmp = std::min(val1,val7); val7 = std::max(val1,val7); val1 = tmp;
      tmp = std::min(val2,val6); val6 = std::max(val2,val6); val2 = tmp; val3 = std::max(val1,val3);
      tmp = std::min(val4,val7); val7 = std::max(val4,val7); val4 = tmp; val8 = std::min(val8,val10);
      val5 = std::max(val0,val5); val5 = std::max(val2,val5); tmp = std::min(val6,val8); val8 = std::max(val6,val8);
      val5 = std::max(val3,val5); val7 = std::min(val7,val8); val6 = std::max(val4,tmp); tmp = std::min(val4,tmp);
      val5 = std::max(tmp,val5); val6 = std::min(val6,val7);
      return std::max(val5,val6);
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4,
                    T val5, T val6, T val7, T val8, T val9,
                    T val10, T val11, T val12, T val13, T val14,
                    T val15, T val16, T val17, T val18, T val19,
                    T val20, T val21, T val22, T val23, T val24) {
      T tmp = std::min(val0,val1);
      val1 = std::max(val0,val1); val0 = tmp; tmp = std::min(val3,val4); val4 = std::max(val3,val4);
      val3 = tmp; tmp = std::min(val2,val4); val4 = std::max(val2,val4); val2 = std::min(tmp,val3);
      val3 = std::max(tmp,val3); tmp = std::min(val6,val7); val7 = std::max(val6,val7); val6 = tmp;
      tmp = std::min(val5,val7); val7 = std::max(val5,val7); val5 = std::min(tmp,val6); val6 = std::max(tmp,val6);
      tmp = std::min(val9,val10); val10 = std::max(val9,val10); val9 = tmp; tmp = std::min(val8,val10);
      val10 = std::max(val8,val10); val8 = std::min(tmp,val9); val9 = std::max(tmp,val9);
      tmp = std::min(val12,val13); val13 = std::max(val12,val13); val12 = tmp; tmp = std::min(val11,val13);
      val13 = std::max(val11,val13); val11 = std::min(tmp,val12); val12 = std::max(tmp,val12);
      tmp = std::min(val15,val16); val16 = std::max(val15,val16); val15 = tmp; tmp = std::min(val14,val16);
      val16 = std::max(val14,val16); val14 = std::min(tmp,val15); val15 = std::max(tmp,val15);
      tmp = std::min(val18,val19); val19 = std::max(val18,val19); val18 = tmp; tmp = std::min(val17,val19);
      val19 = std::max(val17,val19); val17 = std::min(tmp,val18); val18 = std::max(tmp,val18);
      tmp = std::min(val21,val22); val22 = std::max(val21,val22); val21 = tmp; tmp = std::min(val20,val22);
      val22 = std::max(val20,val22); val20 = std::min(tmp,val21); val21 = std::max(tmp,val21);
      tmp = std::min(val23,val24); val24 = std::max(val23,val24); val23 = tmp; tmp = std::min(val2,val5);
      val5 = std::max(val2,val5); val2 = tmp; tmp = std::min(val3,val6); val6 = std::max(val3,val6); val3 = tmp;
      tmp = std::min(val0,val6); val6 = std::max(val0,val6); val0 = std::min(tmp,val3); val3 = std::max(tmp,val3);
      tmp = std::min(val4,val7); val7 = std::max(val4,val7); val4 = tmp; tmp = std::min(val1,val7);
      val7 = std::max(val1,val7); val1 = std::min(tmp,val4); val4 = std::max(tmp,val4); tmp = std::min(val11,val14);
      val14 = std::max(val11,val14); val11 = tmp; tmp = std::min(val8,val14); val14 = std::max(val8,val14);
      val8 = std::min(tmp,val11); val11 = std::max(tmp,val11); tmp = std::min(val12,val15);
      val15 = std::max(val12,val15); val12 = tmp; tmp = std::min(val9,val15); val15 = std::max(val9,val15);
      val9 = std::min(tmp,val12); val12 = std::max(tmp,val12); tmp = std::min(val13,val16);
      val16 = std::max(val13,val16); val13 = tmp; tmp = std::min(val10,val16); val16 = std::max(val10,val16);
      val10 = std::min(tmp,val13); val13 = std::max(tmp,val13); tmp = std::min(val20,val23);
      val23 = std::max(val20,val23); val20 = tmp; tmp = std::min(val17,val23); val23 = std::max(val17,val23);
      val17 = std::min(tmp,val20); val20 = std::max(tmp,val20); tmp = std::min(val21,val24);
      val24 = std::max(val21,val24); val21 = tmp; tmp = std::min(val18,val24); val24 = std::max(val18,val24);
      val18 = std::min(tmp,val21); val21 = std::max(tmp,val21); tmp = std::min(val19,val22);
      val22 = std::max(val19,val22); val19 = tmp; val17 = std::max(val8,val17); tmp = std::min(val9,val18);
      val18 = std::max(val9,val18); val9 = tmp; tmp = std::min(val0,val18); val18 = std::max(val0,val18);
      val9 = std::max(tmp,val9); tmp = std::min(val10,val19); val19 = std::max(val10,val19); val10 = tmp;
      tmp = std::min(val1,val19); val19 = std::max(val1,val19); val1 = std::min(tmp,val10);
      val10 = std::max(tmp,val10); tmp = std::min(val11,val20); val20 = std::max(val11,val20); val11 = tmp;
      tmp = std::min(val2,val20); val20 = std::max(val2,val20); val11 = std::max(tmp,val11);
      tmp = std::min(val12,val21); val21 = std::max(val12,val21); val12 = tmp; tmp = std::min(val3,val21);
      val21 = std::max(val3,val21); val3 = std::min(tmp,val12); val12 = std::max(tmp,val12);
      tmp = std::min(val13,val22); val22 = std::max(val13,val22); val4 = std::min(val4,val22);
      val13 = std::max(val4,tmp); tmp = std::min(val4,tmp); val4 = tmp; tmp = std::min(val14,val23);
      val23 = std::max(val14,val23); val14 = tmp; tmp = std::min(val5,val23); val23 = std::max(val5,val23);
      val5 = std::min(tmp,val14); val14 = std::max(tmp,val14); tmp = std::min(val15,val24);
      val24 = std::max(val15,val24); val15 = tmp; val6 = std::min(val6,val24); tmp = std::min(val6,val15);
      val15 = std::max(val6,val15); val6 = tmp; tmp = std::min(val7,val16); val7 = std::min(tmp,val19);
      tmp = std::min(val13,val21); val15 = std::min(val15,val23); tmp = std::min(val7,tmp);
      val7 = std::min(tmp,val15); val9 = std::max(val1,val9); val11 = std::max(val3,val11);
      val17 = std::max(val5,val17); val17 = std::max(val11,val17); val17 = std::max(val9,val17);
      tmp = std::min(val4,val10); val10 = std::max(val4,val10); val4 = tmp; tmp = std::min(val6,val12);
      val12 = std::max(val6,val12); val6 = tmp; tmp = std::min(val7,val14); val14 = std::max(val7,val14);
      val7 = tmp; tmp = std::min(val4,val6); val6 = std::max(val4,val6); val7 = std::max(tmp,val7);
      tmp = std::min(val12,val14); val14 = std::max(val12,val14); val12 = tmp; val10 = std::min(val10,val14);
      tmp = std::min(val6,val7); val7 = std::max(val6,val7); val6 = tmp; tmp = std::min(val10,val12);
      val12 = std::max(val10,val12); val10 = std::max(val6,tmp); tmp = std::min(val6,tmp);
      val17 = std::max(tmp,val17); tmp = std::min(val12,val17); val17 = std::max(val12,val17); val12 = tmp;
      val7 = std::min(val7,val17); tmp = std::min(val7,val10); val10 = std::max(val7,val10); val7 = tmp;
      tmp = std::min(val12,val18); val18 = std::max(val12,val18); val12 = std::max(val7,tmp);
      val10 = std::min(val10,val18); tmp = std::min(val12,val20); val20 = std::max(val12,val20); val12 = tmp;
      tmp = std::min(val10,val20);
      return std::max(tmp,val12);
    }

    template<typename T>
    inline T median(T val0, T val1, T val2, T val3, T val4, T val5, T val6,
                    T val7, T val8, T val9, T val10, T val11, T val12, T val13,
                    T val14, T val15, T val16, T val17, T val18, T val19, T val20,
                    T val21, T val22, T val23, T val24, T val25, T val26, T val27,
                    T val28, T val29, T val30, T val31, T val32, T val33, T val34,
                    T val35, T val36, T val37, T val38, T val39, T val40, T val41,
                    T val42, T val43, T val44, T val45, T val46, T val47, T val48) {
      T tmp = std::min(val0,val32);
      val32 = std::max(val0,val32); val0 = tmp; tmp = std::min(val1,val33); val33 = std::max(val1,val33); val1 = tmp;
      tmp = std::min(val2,val34); val34 = std::max(val2,val34); val2 = tmp; tmp = std::min(val3,val35);
      val35 = std::max(val3,val35); val3 = tmp; tmp = std::min(val4,val36); val36 = std::max(val4,val36); val4 = tmp;
      tmp = std::min(val5,val37); val37 = std::max(val5,val37); val5 = tmp; tmp = std::min(val6,val38);
      val38 = std::max(val6,val38); val6 = tmp; tmp = std::min(val7,val39); val39 = std::max(val7,val39); val7 = tmp;
      tmp = std::min(val8,val40); val40 = std::max(val8,val40); val8 = tmp; tmp = std::min(val9,val41);
      val41 = std::max(val9,val41); val9 = tmp; tmp = std::min(val10,val42); val42 = std::max(val10,val42);
      val10 = tmp; tmp = std::min(val11,val43); val43 = std::max(val11,val43); val11 = tmp;
      tmp = std::min(val12,val44); val44 = std::max(val12,val44); val12 = tmp; tmp = std::min(val13,val45);
      val45 = std::max(val13,val45); val13 = tmp; tmp = std::min(val14,val46); val46 = std::max(val14,val46);
      val14 = tmp; tmp = std::min(val15,val47); val47 = std::max(val15,val47); val15 = tmp;
      tmp = std::min(val16,val48); val48 = std::max(val16,val48); val16 = tmp; tmp = std::min(val0,val16);
      val16 = std::max(val0,val16); val0 = tmp; tmp = std::min(val1,val17); val17 = std::max(val1,val17);
      val1 = tmp; tmp = std::min(val2,val18); val18 = std::max(val2,val18); val2 = tmp; tmp = std::min(val3,val19);
      val19 = std::max(val3,val19); val3 = tmp; tmp = std::min(val4,val20); val20 = std::max(val4,val20); val4 = tmp;
      tmp = std::min(val5,val21); val21 = std::max(val5,val21); val5 = tmp; tmp = std::min(val6,val22);
      val22 = std::max(val6,val22); val6 = tmp; tmp = std::min(val7,val23); val23 = std::max(val7,val23); val7 = tmp;
      tmp = std::min(val8,val24); val24 = std::max(val8,val24); val8 = tmp; tmp = std::min(val9,val25);
      val25 = std::max(val9,val25); val9 = tmp; tmp = std::min(val10,val26); val26 = std::max(val10,val26);
      val10 = tmp; tmp = std::min(val11,val27); val27 = std::max(val11,val27); val11 = tmp;
      tmp = std::min(val12,val28); val28 = std::max(val12,val28); val12 = tmp; tmp = std::min(val13,val29);
      val29 = std::max(val13,val29); val13 = tmp; tmp = std::min(val14,val30); val30 = std::max(val14,val30);
      val14 = tmp; tmp = std::min(val15,val31); val31 = std::max(val15,val31); val15 = tmp;
      tmp = std::min(val32,val48); val48 = std::max(val32,val48); val32 = tmp; tmp = std::min(val16,val32);
      val32 = std::max(val16,val32); val16 = tmp; tmp = std::min(val17,val33); val33 = std::max(val17,val33);
      val17 = tmp; tmp = std::min(val18,val34); val34 = std::max(val18,val34); val18 = tmp;
      tmp = std::min(val19,val35); val35 = std::max(val19,val35); val19 = tmp; tmp = std::min(val20,val36);
      val36 = std::max(val20,val36); val20 = tmp; tmp = std::min(val21,val37); val37 = std::max(val21,val37);
      val21 = tmp; tmp = std::min(val22,val38); val38 = std::max(val22,val38); val22 = tmp;
      tmp = std::min(val23,val39); val39 = std::max(val23,val39); val23 = tmp; tmp = std::min(val24,val40);
      val40 = std::max(val24,val40); val24 = tmp; tmp = std::min(val25,val41); val41 = std::max(val25,val41);
      val25 = tmp; tmp = std::min(val26,val42); val42 = std::max(val26,val42); val26 = tmp;
      tmp = std::min(val27,val43); val43 = std::max(val27,val43); val27 = tmp; tmp = std::min(val28,val44);
      val44 = std::max(val28,val44); val28 = tmp; tmp = std::min(val29,val45); val45 = std::max(val29,val45);
      val29 = tmp; tmp = std::min(val30,val46); val46 = std::max(val30,val46); val30 = tmp;
      tmp = std::min(val31,val47); val47 = std::max(val31,val47); val31 = tmp; tmp = std::min(val0,val8);
      val8 = std::max(val0,val8); val0 = tmp; tmp = std::min(val1,val9); val9 = std::max(val1,val9); val1 = tmp;
      tmp = std::min(val2,val10); val10 = std::max(val2,val10); val2 = tmp; tmp = std::min(val3,val11);
      val11 = std::max(val3,val11); val3 = tmp; tmp = std::min(val4,val12); val12 = std::max(val4,val12); val4 = tmp;
      tmp = std::min(val5,val13); val13 = std::max(val5,val13); val5 = tmp; tmp = std::min(val6,val14);
      val14 = std::max(val6,val14); val6 = tmp; tmp = std::min(val7,val15); val15 = std::max(val7,val15); val7 = tmp;
      tmp = std::min(val16,val24); val24 = std::max(val16,val24); val16 = tmp; tmp = std::min(val17,val25);
      val25 = std::max(val17,val25); val17 = tmp; tmp = std::min(val18,val26); val26 = std::max(val18,val26);
      val18 = tmp; tmp = std::min(val19,val27); val27 = std::max(val19,val27); val19 = tmp;
      tmp = std::min(val20,val28); val28 = std::max(val20,val28); val20 = tmp; tmp = std::min(val21,val29);
      val29 = std::max(val21,val29); val21 = tmp; tmp = std::min(val22,val30); val30 = std::max(val22,val30);
      val22 = tmp; tmp = std::min(val23,val31); val31 = std::max(val23,val31); val23 = tmp;
      tmp = std::min(val32,val40); val40 = std::max(val32,val40); val32 = tmp; tmp = std::min(val33,val41);
      val41 = std::max(val33,val41); val33 = tmp; tmp = std::min(val34,val42); val42 = std::max(val34,val42);
      val34 = tmp; tmp = std::min(val35,val43); val43 = std::max(val35,val43); val35 = tmp;
      tmp = std::min(val36,val44); val44 = std::max(val36,val44); val36 = tmp; tmp = std::min(val37,val45);
      val45 = std::max(val37,val45); val37 = tmp; tmp = std::min(val38,val46); val46 = std::max(val38,val46);
      val38 = tmp; tmp = std::min(val39,val47); val47 = std::max(val39,val47); val39 = tmp;
      tmp = std::min(val8,val32); val32 = std::max(val8,val32); val8 = tmp; tmp = std::min(val9,val33);
      val33 = std::max(val9,val33); val9 = tmp; tmp = std::min(val10,val34); val34 = std::max(val10,val34);
      val10 = tmp; tmp = std::min(val11,val35); val35 = std::max(val11,val35); val11 = tmp;
      tmp = std::min(val12,val36); val36 = std::max(val12,val36); val12 = tmp; tmp = std::min(val13,val37);
      val37 = std::max(val13,val37); val13 = tmp; tmp = std::min(val14,val38); val38 = std::max(val14,val38);
      val14 = tmp; tmp = std::min(val15,val39); val39 = std::max(val15,val39); val15 = tmp;
      tmp = std::min(val24,val48); val48 = std::max(val24,val48); val24 = tmp; tmp = std::min(val8,val16);
      val16 = std::max(val8,val16); val8 = tmp; tmp = std::min(val9,val17); val17 = std::max(val9,val17);
      val9 = tmp; tmp = std::min(val10,val18); val18 = std::max(val10,val18); val10 = tmp;
      tmp = std::min(val11,val19); val19 = std::max(val11,val19); val11 = tmp; tmp = std::min(val12,val20);
      val20 = std::max(val12,val20); val12 = tmp; tmp = std::min(val13,val21); val21 = std::max(val13,val21);
      val13 = tmp; tmp = std::min(val14,val22); val22 = std::max(val14,val22); val14 = tmp;
      tmp = std::min(val15,val23); val23 = std::max(val15,val23); val15 = tmp; tmp = std::min(val24,val32);
      val32 = std::max(val24,val32); val24 = tmp; tmp = std::min(val25,val33); val33 = std::max(val25,val33);
      val25 = tmp; tmp = std::min(val26,val34); val34 = std::max(val26,val34); val26 = tmp;
      tmp = std::min(val27,val35); val35 = std::max(val27,val35); val27 = tmp; tmp = std::min(val28,val36);
      val36 = std::max(val28,val36); val28 = tmp; tmp = std::min(val29,val37); val37 = std::max(val29,val37);
      val29 = tmp; tmp = std::min(val30,val38); val38 = std::max(val30,val38); val30 = tmp;
      tmp = std::min(val31,val39); val39 = std::max(val31,val39); val31 = tmp; tmp = std::min(val40,val48);
      val48 = std::max(val40,val48); val40 = tmp; tmp = std::min(val0,val4); val4 = std::max(val0,val4);
      val0 = tmp; tmp = std::min(val1,val5); val5 = std::max(val1,val5); val1 = tmp; tmp = std::min(val2,val6);
      val6 = std::max(val2,val6); val2 = tmp; tmp = std::min(val3,val7); val7 = std::max(val3,val7); val3 = tmp;
      tmp = std::min(val8,val12); val12 = std::max(val8,val12); val8 = tmp; tmp = std::min(val9,val13);
      val13 = std::max(val9,val13); val9 = tmp; tmp = std::min(val10,val14); val14 = std::max(val10,val14);
      val10 = tmp; tmp = std::min(val11,val15); val15 = std::max(val11,val15); val11 = tmp;
      tmp = std::min(val16,val20); val20 = std::max(val16,val20); val16 = tmp; tmp = std::min(val17,val21);
      val21 = std::max(val17,val21); val17 = tmp; tmp = std::min(val18,val22); val22 = std::max(val18,val22);
      val18 = tmp; tmp = std::min(val19,val23); val23 = std::max(val19,val23); val19 = tmp;
      tmp = std::min(val24,val28); val28 = std::max(val24,val28); val24 = tmp; tmp = std::min(val25,val29);
      val29 = std::max(val25,val29); val25 = tmp; tmp = std::min(val26,val30); val30 = std::max(val26,val30);
      val26 = tmp; tmp = std::min(val27,val31); val31 = std::max(val27,val31); val27 = tmp;
      tmp = std::min(val32,val36); val36 = std::max(val32,val36); val32 = tmp; tmp = std::min(val33,val37);
      val37 = std::max(val33,val37); val33 = tmp; tmp = std::min(val34,val38); val38 = std::max(val34,val38);
      val34 = tmp; tmp = std::min(val35,val39); val39 = std::max(val35,val39); val35 = tmp;
      tmp = std::min(val40,val44); val44 = std::max(val40,val44); val40 = tmp; tmp = std::min(val41,val45);
      val45 = std::max(val41,val45); val41 = tmp; tmp = std::min(val42,val46); val46 = std::max(val42,val46);
      val42 = tmp; tmp = std::min(val43,val47); val47 = std::max(val43,val47); val43 = tmp;
      tmp = std::min(val4,val32); val32 = std::max(val4,val32); val4 = tmp; tmp = std::min(val5,val33);
      val33 = std::max(val5,val33); val5 = tmp; tmp = std::min(val6,val34); val34 = std::max(val6,val34);
      val6 = tmp; tmp = std::min(val7,val35); val35 = std::max(val7,val35); val7 = tmp;
      tmp = std::min(val12,val40); val40 = std::max(val12,val40); val12 = tmp; tmp = std::min(val13,val41);
      val41 = std::max(val13,val41); val13 = tmp; tmp = std::min(val14,val42); val42 = std::max(val14,val42);
      val14 = tmp; tmp = std::min(val15,val43); val43 = std::max(val15,val43); val15 = tmp;
      tmp = std::min(val20,val48); val48 = std::max(val20,val48); val20 = tmp; tmp = std::min(val4,val16);
      val16 = std::max(val4,val16); val4 = tmp; tmp = std::min(val5,val17); val17 = std::max(val5,val17);
      val5 = tmp; tmp = std::min(val6,val18); val18 = std::max(val6,val18); val6 = tmp;
      tmp = std::min(val7,val19); val19 = std::max(val7,val19); val7 = tmp; tmp = std::min(val12,val24);
      val24 = std::max(val12,val24); val12 = tmp; tmp = std::min(val13,val25); val25 = std::max(val13,val25);
      val13 = tmp; tmp = std::min(val14,val26); val26 = std::max(val14,val26); val14 = tmp;
      tmp = std::min(val15,val27); val27 = std::max(val15,val27); val15 = tmp; tmp = std::min(val20,val32);
      val32 = std::max(val20,val32); val20 = tmp; tmp = std::min(val21,val33); val33 = std::max(val21,val33);
      val21 = tmp; tmp = std::min(val22,val34); val34 = std::max(val22,val34); val22 = tmp;
      tmp = std::min(val23,val35); val35 = std::max(val23,val35); val23 = tmp; tmp = std::min(val28,val40);
      val40 = std::max(val28,val40); val28 = tmp; tmp = std::min(val29,val41); val41 = std::max(val29,val41);
      val29 = tmp; tmp = std::min(val30,val42); val42 = std::max(val30,val42); val30 = tmp;
      tmp = std::min(val31,val43); val43 = std::max(val31,val43); val31 = tmp; tmp = std::min(val36,val48);
      val48 = std::max(val36,val48); val36 = tmp; tmp = std::min(val4,val8); val8 = std::max(val4,val8);
      val4 = tmp; tmp = std::min(val5,val9); val9 = std::max(val5,val9); val5 = tmp; tmp = std::min(val6,val10);
      val10 = std::max(val6,val10); val6 = tmp; tmp = std::min(val7,val11); val11 = std::max(val7,val11); val7 = tmp;
      tmp = std::min(val12,val16); val16 = std::max(val12,val16); val12 = tmp; tmp = std::min(val13,val17);
      val17 = std::max(val13,val17); val13 = tmp; tmp = std::min(val14,val18); val18 = std::max(val14,val18);
      val14 = tmp; tmp = std::min(val15,val19); val19 = std::max(val15,val19); val15 = tmp;
      tmp = std::min(val20,val24); val24 = std::max(val20,val24); val20 = tmp; tmp = std::min(val21,val25);
      val25 = std::max(val21,val25); val21 = tmp; tmp = std::min(val22,val26); val26 = std::max(val22,val26);
      val22 = tmp; tmp = std::min(val23,val27); val27 = std::max(val23,val27); val23 = tmp;
      tmp = std::min(val28,val32); val32 = std::max(val28,val32); val28 = tmp; tmp = std::min(val29,val33);
      val33 = std::max(val29,val33); val29 = tmp; tmp = std::min(val30,val34); val34 = std::max(val30,val34);
      val30 = tmp; tmp = std::min(val31,val35); val35 = std::max(val31,val35); val31 = tmp;
      tmp = std::min(val36,val40); val40 = std::max(val36,val40); val36 = tmp; tmp = std::min(val37,val41);
      val41 = std::max(val37,val41); val37 = tmp; tmp = std::min(val38,val42); val42 = std::max(val38,val42);
      val38 = tmp; tmp = std::min(val39,val43); val43 = std::max(val39,val43); val39 = tmp;
      tmp = std::min(val44,val48); val48 = std::max(val44,val48); val44 = tmp; tmp = std::min(val0,val2);
      val2 = std::max(val0,val2); val0 = tmp; tmp = std::min(val1,val3); val3 = std::max(val1,val3); val1 = tmp;
      tmp = std::min(val4,val6); val6 = std::max(val4,val6); val4 = tmp; tmp = std::min(val5,val7);
      val7 = std::max(val5,val7); val5 = tmp; tmp = std::min(val8,val10); val10 = std::max(val8,val10); val8 = tmp;
      tmp = std::min(val9,val11); val11 = std::max(val9,val11); val9 = tmp; tmp = std::min(val12,val14);
      val14 = std::max(val12,val14); val12 = tmp; tmp = std::min(val13,val15); val15 = std::max(val13,val15);
      val13 = tmp; tmp = std::min(val16,val18); val18 = std::max(val16,val18); val16 = tmp;
      tmp = std::min(val17,val19); val19 = std::max(val17,val19); val17 = tmp; tmp = std::min(val20,val22);
      val22 = std::max(val20,val22); val20 = tmp; tmp = std::min(val21,val23); val23 = std::max(val21,val23);
      val21 = tmp; tmp = std::min(val24,val26); val26 = std::max(val24,val26); val24 = tmp;
      tmp = std::min(val25,val27); val27 = std::max(val25,val27); val25 = tmp; tmp = std::min(val28,val30);
      val30 = std::max(val28,val30); val28 = tmp; tmp = std::min(val29,val31); val31 = std::max(val29,val31);
      val29 = tmp; tmp = std::min(val32,val34); val34 = std::max(val32,val34); val32 = tmp;
      tmp = std::min(val33,val35); val35 = std::max(val33,val35); val33 = tmp; tmp = std::min(val36,val38);
      val38 = std::max(val36,val38); val36 = tmp; tmp = std::min(val37,val39); val39 = std::max(val37,val39);
      val37 = tmp; tmp = std::min(val40,val42); val42 = std::max(val40,val42); val40 = tmp;
      tmp = std::min(val41,val43); val43 = std::max(val41,val43); val41 = tmp; tmp = std::min(val44,val46);
      val46 = std::max(val44,val46); val44 = tmp; tmp = std::min(val45,val47); val47 = std::max(val45,val47);
      val45 = tmp; tmp = std::min(val2,val32); val32 = std::max(val2,val32); val2 = tmp; tmp = std::min(val3,val33);
      val33 = std::max(val3,val33); val3 = tmp; tmp = std::min(val6,val36); val36 = std::max(val6,val36); val6 = tmp;
      tmp = std::min(val7,val37); val37 = std::max(val7,val37); val7 = tmp; tmp = std::min(val10,val40);
      val40 = std::max(val10,val40); val10 = tmp; tmp = std::min(val11,val41); val41 = std::max(val11,val41);
      val11 = tmp; tmp = std::min(val14,val44); val44 = std::max(val14,val44); val14 = tmp;
      tmp = std::min(val15,val45); val45 = std::max(val15,val45); val15 = tmp; tmp = std::min(val18,val48);
      val48 = std::max(val18,val48); val18 = tmp; tmp = std::min(val2,val16); val16 = std::max(val2,val16);
      val2 = tmp; tmp = std::min(val3,val17); val17 = std::max(val3,val17); val3 = tmp;
      tmp = std::min(val6,val20); val20 = std::max(val6,val20); val6 = tmp; tmp = std::min(val7,val21);
      val21 = std::max(val7,val21); val7 = tmp; tmp = std::min(val10,val24); val24 = std::max(val10,val24);
      val10 = tmp; tmp = std::min(val11,val25); val25 = std::max(val11,val25); val11 = tmp;
      tmp = std::min(val14,val28); val28 = std::max(val14,val28); val14 = tmp; tmp = std::min(val15,val29);
      val29 = std::max(val15,val29); val15 = tmp; tmp = std::min(val18,val32); val32 = std::max(val18,val32);
      val18 = tmp; tmp = std::min(val19,val33); val33 = std::max(val19,val33); val19 = tmp;
      tmp = std::min(val22,val36); val36 = std::max(val22,val36); val22 = tmp; tmp = std::min(val23,val37);
      val37 = std::max(val23,val37); val23 = tmp; tmp = std::min(val26,val40); val40 = std::max(val26,val40);
      val26 = tmp; tmp = std::min(val27,val41); val41 = std::max(val27,val41); val27 = tmp;
      tmp = std::min(val30,val44); val44 = std::max(val30,val44); val30 = tmp; tmp = std::min(val31,val45);
      val45 = std::max(val31,val45); val31 = tmp; tmp = std::min(val34,val48); val48 = std::max(val34,val48);
      val34 = tmp; tmp = std::min(val2,val8); val8 = std::max(val2,val8); val2 = tmp; tmp = std::min(val3,val9);
      val9 = std::max(val3,val9); val3 = tmp; tmp = std::min(val6,val12); val12 = std::max(val6,val12); val6 = tmp;
      tmp = std::min(val7,val13); val13 = std::max(val7,val13); val7 = tmp; tmp = std::min(val10,val16);
      val16 = std::max(val10,val16); val10 = tmp; tmp = std::min(val11,val17); val17 = std::max(val11,val17);
      val11 = tmp; tmp = std::min(val14,val20); val20 = std::max(val14,val20); val14 = tmp;
      tmp = std::min(val15,val21); val21 = std::max(val15,val21); val15 = tmp; tmp = std::min(val18,val24);
      val24 = std::max(val18,val24); val18 = tmp; tmp = std::min(val19,val25); val25 = std::max(val19,val25);
      val19 = tmp; tmp = std::min(val22,val28); val28 = std::max(val22,val28); val22 = tmp;
      tmp = std::min(val23,val29); val29 = std::max(val23,val29); val23 = tmp; tmp = std::min(val26,val32);
      val32 = std::max(val26,val32); val26 = tmp; tmp = std::min(val27,val33); val33 = std::max(val27,val33);
      val27 = tmp; tmp = std::min(val30,val36); val36 = std::max(val30,val36); val30 = tmp;
      tmp = std::min(val31,val37); val37 = std::max(val31,val37); val31 = tmp; tmp = std::min(val34,val40);
      val40 = std::max(val34,val40); val34 = tmp; tmp = std::min(val35,val41); val41 = std::max(val35,val41);
      val35 = tmp; tmp = std::min(val38,val44); val44 = std::max(val38,val44); val38 = tmp;
      tmp = std::min(val39,val45); val45 = std::max(val39,val45); val39 = tmp; tmp = std::min(val42,val48);
      val48 = std::max(val42,val48); val42 = tmp; tmp = std::min(val2,val4); val4 = std::max(val2,val4);
      val2 = tmp; tmp = std::min(val3,val5); val5 = std::max(val3,val5); val3 = tmp; tmp = std::min(val6,val8);
      val8 = std::max(val6,val8); val6 = tmp; tmp = std::min(val7,val9); val9 = std::max(val7,val9); val7 = tmp;
      tmp = std::min(val10,val12); val12 = std::max(val10,val12); val10 = tmp; tmp = std::min(val11,val13);
      val13 = std::max(val11,val13); val11 = tmp; tmp = std::min(val14,val16); val16 = std::max(val14,val16);
      val14 = tmp; tmp = std::min(val15,val17); val17 = std::max(val15,val17); val15 = tmp;
      tmp = std::min(val18,val20); val20 = std::max(val18,val20); val18 = tmp; tmp = std::min(val19,val21);
      val21 = std::max(val19,val21); val19 = tmp; tmp = std::min(val22,val24); val24 = std::max(val22,val24);
      val22 = tmp; tmp = std::min(val23,val25); val25 = std::max(val23,val25); val23 = tmp;
      tmp = std::min(val26,val28); val28 = std::max(val26,val28); val26 = tmp; tmp = std::min(val27,val29);
      val29 = std::max(val27,val29); val27 = tmp; tmp = std::min(val30,val32); val32 = std::max(val30,val32);
      val30 = tmp; tmp = std::min(val31,val33); val33 = std::max(val31,val33); val31 = tmp;
      tmp = std::min(val34,val36); val36 = std::max(val34,val36); val34 = tmp; tmp = std::min(val35,val37);
      val37 = std::max(val35,val37); val35 = tmp; tmp = std::min(val38,val40); val40 = std::max(val38,val40);
      val38 = tmp; tmp = std::min(val39,val41); val41 = std::max(val39,val41); val39 = tmp;
      tmp = std::min(val42,val44); val44 = std::max(val42,val44); val42 = tmp; tmp = std::min(val43,val45);
      val45 = std::max(val43,val45); val43 = tmp; tmp = std::min(val46,val48); val48 = std::max(val46,val48);
      val46 = tmp; val1 = std::max(val0,val1); val3 = std::max(val2,val3); val5 = std::max(val4,val5);
      val7 = std::max(val6,val7); val9 = std::max(val8,val9); val11 = std::max(val10,val11);
      val13 = std::max(val12,val13); val15 = std::max(val14,val15); val17 = std::max(val16,val17);
      val19 = std::max(val18,val19); val21 = std::max(val20,val21); val23 = std::max(val22,val23);
      val24 = std::min(val24,val25); val26 = std::min(val26,val27); val28 = std::min(val28,val29);
      val30 = std::min(val30,val31); val32 = std::min(val32,val33); val34 = std::min(val34,val35);
      val36 = std::min(val36,val37); val38 = std::min(val38,val39); val40 = std::min(val40,val41);
      val42 = std::min(val42,val43); val44 = std::min(val44,val45); val46 = std::min(val46,val47);
      val32 = std::max(val1,val32); val34 = std::max(val3,val34); val36 = std::max(val5,val36);
      val38 = std::max(val7,val38); val9 = std::min(val9,val40); val11 = std::min(val11,val42);
      val13 = std::min(val13,val44); val15 = std::min(val15,val46); val17 = std::min(val17,val48);
      val24 = std::max(val9,val24); val26 = std::max(val11,val26); val28 = std::max(val13,val28);
      val30 = std::max(val15,val30); val17 = std::min(val17,val32); val19 = std::min(val19,val34);
      val21 = std::min(val21,val36); val23 = std::min(val23,val38); val24 = std::max(val17,val24);
      val26 = std::max(val19,val26); val21 = std::min(val21,val28); val23 = std::min(val23,val30);
      val24 = std::max(val21,val24); val23 = std::min(val23,val26);
      return std::max(val23,val24);
    }

    //! Return sqrt(x^2 + y^2).
    template<typename T>
    inline T hypot(const T x, const T y) {
#if cimg_use_cpp11==1 && !defined(_MSC_VER)
      return std::hypot(x,y);
#else
      return std::sqrt(x*x + y*y);
#endif
    }

    //! Return sqrt(x^2 + y^2 + z^2).
    template<typename T>
    inline T hypot(const T x, const T y, const T z) {
      return std::sqrt(x*x + y*y + z*z);
    }

    //! Return the factorial of n.
    inline double factorial(const int n) {
      if (n<0) return cimg::type<double>::nan();
      if (n<12) { const double tab[] = { 1,1,2,6,24,120,720,5040,40320,362880,3628800,39916800 }; return tab[n]; }
      double res = 2;
      for (int i = 3; i<=n; ++i) res*=i;
      return res;
    }

    //! Return the number of permutations of k objects in a set of n objects.
    inline double permutations(const int k, const int n, const bool with_order) {
      if (n<0 || k<0) return cimg::type<double>::nan();
      if (k>n) return 0;
      double res = 1;

      if (with_order) for (int i = n; i>=n - k + 1; --i) res*=i;
      else for (int i = 1; i<=k; ++i) { res*=(n - i + 1); res/=i; }
      return res;
    }

    inline double _fibonacci(int exp) {
      double
        base = (1 + std::sqrt(5.))/2,
        result = 1/std::sqrt(5.);
      while (exp) {
        if (exp&1) result*=base;
        exp>>=1;
        base*=base;
      }
      return result;
    }

    //! Calculate fibonacci number.
    // (Precise up to n = 78, less precise for n>78).
    inline double fibonacci(const int n) {
      if (n<0) return cimg::type<double>::nan();
      if (n<16) { const double tab[] = { 0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610 }; return tab[n]; }
      if (n<75) // precise up to n = 74, faster than the integer calculation above for n>10
        return (double)((cimg_uint64)(_fibonacci(n) + 0.5));
      if (n<94) { // precise up to n = 78, less precise for n>78 up to n = 93, overflows for n>93
        cimg_uint64
          fn1 = ((cimg_uint64)303836)<<32 | 3861581201UL, // 1304969544928657ULL (avoid C++98 warning with ULL)
          fn2 = ((cimg_uint64)187781)<<32 | 2279239217UL, // 806515533049393ULL
          fn = 0;
        for (int i = 75; i<=n; ++i) { fn = fn1 + fn2; fn2 = fn1; fn1 = fn; }
        return (double)fn;
      }
      return _fibonacci(n); // Not precise, but better than the wrong overflowing calculation
    }

    //! Wave function.
    /**
       \param x Value to evaluate.
       \param type Wave type.
       Can be { 0:Square | 1:Triangular | 2:Ascending sawtooth | 3: Descending sawtooth | 4:Sinusoidal }.
       \note A wave function has a period of 1, and has value in [-1,1].
       \return Function value.
    **/
    inline double wave(const double x, const unsigned int type=4) {
      const double p = cimg::frac(x);
      double res = 0;
      switch (type) {
      case 0 : // Square
        res = p<0.5?1:-1;
        break;
      case 1 : // Triangle
        res = p<0.25?4*p:p>0.75?4*(p - 1):1 - 4*(p - 0.25);
        break;
      case 2 : // Ascending sawtooth
        res = 2*(p - 0.5);
        break;
      case 3 : // Descending sawtooth
        res = -2*(p - 0.5);
        break;
      default : // Sine
        res = std::sin(2*cimg::PI*p);
      }
      return res;
    }

    //! Calculate greatest common divisor of two integers.
    template<typename T>
    inline T gcd(T a, T b) {
      if (a<0) a = -a;
      if (b<0) b = -b;
      while (a) { const T c = a; a = b%a; b = c; }
      return b;
    }

    //! Calculate least common multiple of two integers.
    template<typename T>
    inline T lcm(T a, T b) {
      if (a<0) a = -a;
      if (!a && !b) return 0;
      return a*(b/gcd(a,b));
    }

    //! Convert character to lower case.
    inline char lowercase(const char x) {
      return (char)((x<'A'||x>'Z')?x:x - 'A' + 'a');
    }
    inline double lowercase(const double x) {
      return (double)((x<'A'||x>'Z')?x:x - 'A' + 'a');
    }

    //! Convert C-string to lower case.
    inline void lowercase(char *const str) {
      if (str) for (char *ptr = str; *ptr; ++ptr) *ptr = lowercase(*ptr);
    }

    //! Convert character to upper case.
    inline char uppercase(const char x) {
      return (char)((x<'a'||x>'z')?x:x - 'a' + 'A');
    }

    inline double uppercase(const double x) {
      return (double)((x<'a'||x>'z')?x:x - 'a' + 'A');
    }

    //! Convert C-string to upper case.
    inline void uppercase(char *const str) {
      if (str) for (char *ptr = str; *ptr; ++ptr) *ptr = uppercase(*ptr);
    }

    //! Return \c true if input character is blank (space, tab, or non-printable character).
    inline bool is_blank(const char c) {
      return (unsigned char)c<=' ';
    }

    // Return \c true if specified argument is in set \c [a-zA-Z0-9_].
    inline bool is_varchar(const char c) {
      return (c>='a' && c<='z') || (c>='A' && c<='Z') || (c>='0' && c<='9') || c=='_';
    }

    //! Return \c true if argument \p str can be considered as a regular variable name.
    inline bool is_varname(const char *const str, const unsigned int length=~0U) {
      if (*str>='0' && *str<='9') return false;
      for (unsigned int l = 0; l<length && str[l]; ++l)
        if (!is_varchar(str[l])) return false;
      return true;
    }

    //! Read value in a C-string.
    /**
       \param str C-string containing the float value to read.
       \return Read value.
       \note Same as <tt>std::atof()</tt> extended to manage the retrieval of fractions from C-strings,
       as in <em>"1/2"</em>.
    **/
    inline double atof(const char *const str) {
      double x = 0, y = 1;
      return str && cimg_sscanf(str,"%lf/%lf",&x,&y)>0?x/y:0;
    }

    // Portable Version of 'strtoll()' (C++98 / C++11)
    inline cimg_int64 strtoll(const char* str, char** endptr, int base) {
#if cimg_use_cpp11==1
      return (cimg_int64)std::strtoll(str,endptr,base);
#else
      // C++-98 fallback version (std::strtol is guaranteed to be >= 32 bits).
      return (cimg_int64)std::strtol(str,endptr,base);
#endif
    }

    //! Compare the first \p length characters of two C-strings, ignoring the case.
    /**
       \param str1 C-string.
       \param str2 C-string.
       \param length Number of characters to compare.
       \return \c 0 if the two strings are equal, something else otherwise.
       \note This function has to be defined since it is not provided by all C++-compilers (not ANSI).
    **/
    inline int strncasecmp(const char *const str1, const char *const str2, const int length) {
      if (!length) return 0;
      if (!str1) return str2?-1:0;
      const char *nstr1 = str1, *nstr2 = str2;
      int k, diff = 0;
      for (k = 0; k<length && !(diff = lowercase(*nstr1) - lowercase(*nstr2)); ++k) { ++nstr1; ++nstr2; }
      return k!=length?diff:0;
    }

    //! Compare two C-strings, ignoring the case.
    /**
       \param str1 C-string.
       \param str2 C-string.
       \return \c 0 if the two strings are equal, something else otherwise.
       \note This function has to be defined since it is not provided by all C++-compilers (not ANSI).
    **/
    inline int strcasecmp(const char *const str1, const char *const str2) {
      if (!str1) return str2?-1:0;
      const int
        l1 = (int)std::strlen(str1),
        l2 = (int)std::strlen(str2);
      return cimg::strncasecmp(str1,str2,1 + (l1<l2?l1:l2));
    }

    //! Ellipsize a string.
    /**
       \param str C-string.
       \param l Max number of printed characters.
       \param is_ending Indicates whether the dots are placed at the end or at the center of the ellipsized string.
    **/
    inline char *strellipsize(char *const str, const unsigned int l=64,
                              const bool is_ending=true) {
      if (!str) return str;
      const unsigned int nl = l<5?5:l, ls = (unsigned int)std::strlen(str);
      if (ls<=nl) return str;
      if (is_ending) std::strcpy(str + nl - 5,"(...)");
      else {
        const unsigned int ll = (nl - 5)/2 + 1 - (nl%2), lr = nl - ll - 5;
        std::strcpy(str + ll,"(...)");
        std::memmove(str + ll + 5,str + ls - lr,lr);
      }
      str[nl] = 0;
      return str;
    }

    //! Ellipsize a string.
    /**
       \param str C-string.
       \param res output C-string.
       \param l Max number of printed characters. String 'res' must be a size of at least 'l+1'.
       \param is_ending Indicates whether the dots are placed at the end or at the center of the ellipsized string.
    **/
    inline char *strellipsize(const char *const str, char *const res, const unsigned int l=64,
                              const bool is_ending=true) {
      const unsigned int nl = l<5?5:l, ls = (unsigned int)std::strlen(str);
      if (ls<=nl) { std::strcpy(res,str); return res; }
      if (is_ending) {
        std::strncpy(res,str,nl - 5);
        std::strcpy(res + nl -5,"(...)");
      } else {
        const unsigned int ll = (nl - 5)/2 + 1 - (nl%2), lr = nl - ll - 5;
        std::strncpy(res,str,ll);
        std::strcpy(res + ll,"(...)");
        std::strncpy(res + ll + 5,str + ls - lr,lr);
      }
      res[nl] = 0;
      return res;
    }

    //! Remove delimiters on the start and/or end of a C-string.
    /**
       \param[in,out] str C-string to work with (modified at output).
       \param delimiter Delimiter character code to remove.
       \param is_symmetric Indicates whether the removal is done only if delimiters are symmetric
       (both at the beginning and the end of \c s).
       \param is_iterative Indicates whether the removal is done if several iterations are possible.
       \return \c true if delimiters have been removed, \c false otherwise.
   **/
    inline bool strpare(char *const str, const char delimiter,
                        const bool is_symmetric, const bool is_iterative) {
      if (!str) return false;
      const int l = (int)std::strlen(str);
      int p, q;
      if (is_symmetric) for (p = 0, q = l - 1; p<q && str[p]==delimiter && str[q]==delimiter; ) {
          --q; ++p; if (!is_iterative) break;
        } else {
        for (p = 0; p<l && str[p]==delimiter; ) { ++p; if (!is_iterative) break; }
        for (q = l - 1; q>p && str[q]==delimiter; ) { --q; if (!is_iterative) break; }
      }
      const int n = q - p + 1;
      if (n!=l) { std::memmove(str,str + p,(unsigned int)n); str[n] = 0; return true; }
      return false;
    }

    //! Remove white spaces on the start and/or end of a C-string.
    inline bool strpare(char *const str, const bool is_symmetric, const bool is_iterative) {
      if (!str) return false;
      const int l = (int)std::strlen(str);
      int p, q;
      if (is_symmetric) for (p = 0, q = l - 1; p<q && is_blank(str[p]) && is_blank(str[q]); ) {
          --q; ++p; if (!is_iterative) break;
        } else {
        for (p = 0; p<l && is_blank(str[p]); ) { ++p; if (!is_iterative) break; }
        for (q = l - 1; q>p && is_blank(str[q]); ) { --q; if (!is_iterative) break; }
      }
      const int n = q - p + 1;
      if (n!=l) { std::memmove(str,str + p,(unsigned int)n); str[n] = 0; return true; }
      return false;
    }

    //! Replace reserved characters (for Windows filename) by another character.
    /**
       \param[in,out] str C-string to work with (modified at output).
       \param[in] c Replacement character.
    **/
    inline void strwindows_reserved(char *const str, const char c='_') {
      for (char *s = str; *s; ++s) {
        const char i = *s;
        if (i=='<' || i=='>' || i==':' || i=='\"' || i=='/' || i=='\\' || i=='|' || i=='?' || i=='*') *s = c;
      }
    }

    //! Replace escape sequences in C-strings by character values.
    /**
       \param[in,out] str C-string to work with (modified at output).
    **/
    inline void strunescape(char *const str) {
#define cimg_strunescape(ci,co) case ci : *nd = co; ++ns; break;

      unsigned char val = 0;
      for (char *ns = str, *nd = str; *ns || (bool)(*nd = 0); ++nd) if (*ns=='\\') switch (*(++ns)) {
            cimg_strunescape('a','\a');
            cimg_strunescape('b','\b');
            cimg_strunescape('e',0x1B);
            cimg_strunescape('f','\f');
            cimg_strunescape('n','\n');
            cimg_strunescape('r','\r');
            cimg_strunescape('t','\t');
            cimg_strunescape('v','\v');
            cimg_strunescape('\\','\\');
            cimg_strunescape('\'','\'');
            cimg_strunescape('\"','\"');
            cimg_strunescape('\?','\?');
          case '0' : case '1' : case '2' : case '3' : case '4' : case '5' : case '6' : case '7' :
            val = (unsigned char)(*(ns++) - '0');
            if (*ns>='0' && *ns<='7') (val<<=3)|=*(ns++) - '0';
            if (*ns>='0' && *ns<='7') (val<<=3)|=*(ns++) - '0';
            *nd = (char)val;
            break;
          case 'x' : {
            char c = lowercase(*(++ns));
            if ((c>='0' && c<='9') || (c>='a' && c<='f')) {
              val = (unsigned char)(c<='9'?c - '0':c - 'a' + 10);
              c = lowercase(*(++ns));
              if ((c>='0' && c<='9') || (c>='a' && c<='f')) {
                (val<<=4)|=(c<='9'?c - '0':c - 'a' + 10);
                ++ns;
              }
              *nd = (char)val;
            } else *nd = c;
          } break;
          case 'u' : { // UTF-8 BMP
            char c1, c2, c3, c4;
            if ((((c1 = lowercase(ns[1]))>='0' && c1<='9') || (c1>='a' && c1<='f')) &&
                (((c2 = lowercase(ns[2]))>='0' && c2<='9') || (c2>='a' && c2<='f')) &&
                (((c3 = lowercase(ns[3]))>='0' && c3<='9') || (c3>='a' && c3<='f')) &&
                (((c4 = lowercase(ns[4]))>='0' && c4<='9') || (c4>='a' && c4<='f'))) {
              c1 = (c1<='9'?c1 - '0':c1 - 'a' + 10);
              c2 = (c2<='9'?c2 - '0':c2 - 'a' + 10);
              c3 = (c3<='9'?c3 - '0':c3 - 'a' + 10);
              c4 = (c4<='9'?c4 - '0':c4 - 'a' + 10);
              const unsigned int ival =
                ((unsigned int)c1<<12) | ((unsigned int)c2<<8) | ((unsigned int)c3<<4) | c4;
              if (ival<=0x007f) *nd = (char)ival;
              else if (ival<=0x07ff) {
                *(nd++) = (char)((ival>>6)|0xc0);
                *nd = (char)((ival&0x3f)|0x80);
              } else {
                *(nd++) = (char)((ival>>12)|0xe0);
                *(nd++) = (char)(((ival>>6)&0x3f)|0x80);
                *nd = (char)((ival&0x3f)|0x80);
              }
              ns+=5;
            } else *nd = *(ns++);
          } break;
          case 'U' : { // UTF-8 astral planes
            char c1, c2, c3, c4, c5, c6, c7, c8;
            if ((((c1 = lowercase(ns[1]))>='0' && c1<='9') || (c1>='a' && c1<='f')) &&
                (((c2 = lowercase(ns[2]))>='0' && c2<='9') || (c2>='a' && c2<='f')) &&
                (((c3 = lowercase(ns[3]))>='0' && c3<='9') || (c3>='a' && c3<='f')) &&
                (((c4 = lowercase(ns[4]))>='0' && c4<='9') || (c4>='a' && c4<='f')) &&
                (((c5 = lowercase(ns[5]))>='0' && c5<='9') || (c5>='a' && c5<='f')) &&
                (((c6 = lowercase(ns[6]))>='0' && c6<='9') || (c6>='a' && c6<='f')) &&
                (((c7 = lowercase(ns[7]))>='0' && c7<='9') || (c7>='a' && c7<='f')) &&
                (((c8 = lowercase(ns[8]))>='0' && c8<='9') || (c8>='a' && c8<='f'))) {
              c1 = (c1<='9'?c1 - '0':c1 - 'a' + 10);
              c2 = (c2<='9'?c2 - '0':c2 - 'a' + 10);
              c3 = (c3<='9'?c3 - '0':c3 - 'a' + 10);
              c4 = (c4<='9'?c4 - '0':c4 - 'a' + 10);
              c5 = (c5<='9'?c5 - '0':c5 - 'a' + 10);
              c6 = (c6<='9'?c6 - '0':c6 - 'a' + 10);
              c7 = (c7<='9'?c7 - '0':c7 - 'a' + 10);
              c8 = (c8<='9'?c8 - '0':c8 - 'a' + 10);
              const unsigned int ival =
                ((unsigned int)c1<<28) | ((unsigned int)c2<<24) | ((unsigned int)c3<<20) | ((unsigned int)c4<<16) |
                ((unsigned int)c5<<12) | ((unsigned int)c6<<8) | ((unsigned int)c7<<4) | (unsigned int)c8;
              if (ival<=0x007f) *nd = (char)ival;
              else if (ival<=0x07ff) {
                *(nd++) = (char)((ival>>6)|0xc0);
                *nd = (char)((ival&0x3f)|0x80);
              } else if (ival<=0xffff) {
                *(nd++) = (char)((ival>>12)|0xe0);
                *(nd++) = (char)(((ival>>6)&0x3f)|0x80);
                *nd = (char)((ival&0x3f)|0x80);
              } else {
                *(nd++) = (char)((ival>>18)|0xf0);
                *(nd++) = (char)(((ival>>12)&0x3f)|0x80);
                *(nd++) = (char)(((ival>>6)&0x3f)|0x80);
                *nd = (char)((ival&0x3f)|0x80);
              }
              ns+=9;
            } else *nd = *(ns++);
          } break;
          default : if (*ns) *nd = *(ns++);
          }
        else *nd = *(ns++);
    }

    // Return a temporary string describing the size of a memory buffer.
    inline const char *strbuffersize(const cimg_ulong size);

    // Return string that identifies the running OS.
    inline const char *stros() {
#if defined(linux) || defined(__linux) || defined(__linux__)
      static const char *const str = "Linux";
#elif defined(sun) || defined(__sun)
      static const char *const str = "Sun OS";
#elif defined(BSD) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__FreeBSD__) || defined (__DragonFly__)
      static const char *const str = "BSD";
#elif defined(sgi) || defined(__sgi)
      static const char *const str = "Irix";
#elif defined(__MACOSX__) || defined(__APPLE__)
      static const char *const str = "Mac OS";
#elif defined(unix) || defined(__unix) || defined(__unix__)
      static const char *const str = "Generic Unix";
#elif defined(_MSC_VER) || defined(WIN32)  || defined(_WIN32) || defined(__WIN32__) || \
  defined(WIN64) || defined(_WIN64) || defined(__WIN64__)
      static const char *const str = "Windows";
#else
      const char
        *const _str1 = std::getenv("OSTYPE"),
        *const _str2 = _str1?_str1:std::getenv("OS"),
        *const str = _str2?_str2:"Unknown OS";
#endif
      return str;
    }

    //! Return the basename of a filename.
    inline const char* basename(const char *const s, const char separator=cimg_directory_separator)  {
      const char *p = 0, *np = s;
      while (np>=s && (p=np)) np = std::strchr(np,separator) + 1;
      return p;
    }

    // Return a random filename.
    inline const char* filenamerand() {
      cimg::mutex(6);
      static char randomid[9];
      for (unsigned int k = 0; k<8; ++k) {
        const int v = (int)cimg::rand(65535)%3;
        randomid[k] = (char)(v==0?('0' + ((int)cimg::rand(65535)%10)):
                             (v==1?('a' + ((int)cimg::rand(65535)%26)):
                              ('A' + ((int)cimg::rand(65535)%26))));
      }
      cimg::mutex(6,0);
      return randomid;
    }

    // Convert filename to a Windows-style filename (short path name).
    inline void winformat_string(char *const str) {
      if (str && *str) {
#if cimg_OS==2
        char *const nstr = new char[MAX_PATH];
        if (GetShortPathNameA(str,nstr,MAX_PATH)) std::strcpy(str,nstr);
        delete[] nstr;
#endif
      }
    }

    // Open a file (similar to std::fopen(), but with wide character support on Windows).
    inline std::FILE *std_fopen(const char *const path, const char *const mode);

    //! Open a file.
    /**
       \param path Path of the filename to open.
       \param mode C-string describing the opening mode.
       \return Opened file.
       \note Same as <tt>std::fopen()</tt> but throw a \c CImgIOException when
       the specified file cannot be opened, instead of returning \c 0.
    **/
    inline std::FILE *fopen(const char *const path, const char *const mode) {
      if (!path)
        throw CImgArgumentException("cimg::fopen(): Specified file path is (null).");
      if (!mode)
        throw CImgArgumentException("cimg::fopen(): File '%s', specified mode is (null).",
                                    path);
      std::FILE *res = 0;
      if (*path=='-' && (!path[1] || path[1]=='.')) {
        res = (*mode=='r')?cimg::_stdin():cimg::_stdout();
#if cimg_OS==2
        if (*mode && mode[1]=='b') { // Force stdin/stdout to be in binary mode
#ifdef __BORLANDC__
          if (setmode(_fileno(res),0x8000)==-1) res = 0;
#else
          if (_setmode(_fileno(res),0x8000)==-1) res = 0;
#endif
        }
#endif
      } else res = cimg::std_fopen(path,mode);
      if (!res) throw CImgIOException("cimg::fopen(): Failed to open file '%s' with mode '%s'.",
                                      path,mode);
      return res;
    }

    //! Close a file.
    /**
       \param file File to close.
       \return \c 0 if file has been closed properly, something else otherwise.
       \note Same as <tt>std::fclose()</tt> but display a warning message if
       the file has not been closed properly.
    **/
    inline int fclose(std::FILE *file) {
      if (!file) { warn("cimg::fclose(): Specified file is (null)."); return 0; }
      if (file==cimg::_stdin(false) || file==cimg::_stdout(false)) return 0;
      const int errn = std::fclose(file);
      if (errn!=0) warn("cimg::fclose(): Error code %d returned during file closing.",
                        errn);
      return errn;
    }

    //! Version of 'fseek()' that supports >=64bits offsets everywhere (for Windows).
    inline int fseek(FILE *stream, cimg_long offset, int origin) {
#if defined(WIN64) || defined(_WIN64) || defined(__WIN64__)
      return _fseeki64(stream,(__int64)offset,origin);
#else
      return std::fseek(stream,offset,origin);
#endif
    }

    //! Version of 'ftell()' that supports >=64bits offsets everywhere (for Windows).
    inline cimg_long ftell(FILE *stream) {
#if defined(WIN64) || defined(_WIN64) || defined(__WIN64__)
      return (cimg_long)_ftelli64(stream);
#else
      return (cimg_long)std::ftell(stream);
#endif
    }

    // Get the file or directory attributes with support for UTF-8 paths (Windows only).
#if cimg_OS==2
    inline DWORD win_getfileattributes(const char *const path);
    inline BOOL win_getfileattributesEx(const char* const path, WIN32_FILE_ATTRIBUTE_DATA* attr);
#endif

    //! Check if a path is a directory.
    /**
       \param path Specified path to test.
    **/
    inline bool is_directory(const char *const path) {
      if (!path || !*path) return false;
#if cimg_OS==1
      struct stat st_buf;
      return (!stat(path,&st_buf) && S_ISDIR(st_buf.st_mode));
#elif cimg_OS==2
      const DWORD res = win_getfileattributes(path);
      return res!=INVALID_FILE_ATTRIBUTES && (res&FILE_ATTRIBUTE_DIRECTORY);
#else
      return false;
#endif
    }

    //! Check if a path is a file.
    /**
       \param path Specified path to test.
    **/
    inline bool is_file(const char *const path) {
      if (!path || !*path) return false;
#if cimg_OS==2
      const DWORD res = cimg::win_getfileattributes(path);
      return res!=INVALID_FILE_ATTRIBUTES && !(res&FILE_ATTRIBUTE_DIRECTORY);
#elif cimg_OS==1
      struct stat st_buf;
      return (!stat(path,&st_buf) && (S_ISREG(st_buf.st_mode) || S_ISFIFO(st_buf.st_mode) ||
                                      S_ISCHR(st_buf.st_mode) || S_ISBLK(st_buf.st_mode)));
#else
      std::FILE *const file = cimg::std_fopen(path,"rb");
      if (!file) return false;
      cimg::fclose(file);
      return !is_directory(path);
#endif
    }

    //! Check if a path exists.
    /**
       \param path Specified path to test.
    **/
    inline bool path_exists(const char *const path) {
      if (!path || !*path) return false;
#if cimg_OS==2
      const DWORD res = cimg::win_getfileattributes(path);
      return res!=INVALID_FILE_ATTRIBUTES;
#elif cimg_OS==1
      return !access(path,F_OK);
#else
      std::FILE *const file = cimg::std_fopen(path,"rb");
      if (!file) return false;
      cimg::fclose(file);
      return true;
#endif
    }

    // Get file size.
    inline cimg_int64 fsize(std::FILE *const file);
    inline cimg_int64 fsize(const char *const filename);

    // Thread-safe version of std::localtime().
    inline struct tm* localtime(const time_t *const time_ptr, struct tm *const result) {
#if cimg_OS==2
      if (!localtime_s(result,time_ptr)) return result;
      return 0;
#elif cimg_OS==1
      return localtime_r(time_ptr,result);
#else
      std::memcpy(result,std::localtime(time_ptr),sizeof(struct tm));
      return result;
#endif
    }

    //! Get last write time of a given file or directory (multiple-attributes version).
    /**
       \param path Specified path to get attributes from.
       \param[in,out] attr Type of requested time attributes.
                      Can be { 0=year | 1=month | 2=day | 3=day of week | 4=hour | 5=minute | 6=second }
                      Replaced by read attributes after return (or -1 if an error occurred).
       \param nb_attr Number of attributes to read/write.
       \return Latest read attribute.
    **/
    template<typename T>
    inline int fdate(const char *const path, T *attr, const unsigned int nb_attr) {
#define _cimg_fdate_err() for (unsigned int i = 0; i<nb_attr; ++i) attr[i] = (T)-1
      int res = -1;
      if (!path || !*path) { _cimg_fdate_err(); return -1; }
      cimg::mutex(6);
#if cimg_OS==2
      WIN32_FILE_ATTRIBUTE_DATA attr_data;
      if (GetFileAttributesExA(path,GetFileExInfoStandard,&attr_data)) {
        FILETIME _ft = attr_data.ftLastWriteTime;
        SYSTEMTIME ft;
        if (FileTimeToSystemTime(&_ft,&ft)) {
          for (unsigned int i = 0; i<nb_attr; ++i) {
            res = (int)(attr[i]==0?ft.wYear:attr[i]==1?ft.wMonth:attr[i]==2?ft.wDay:
                        attr[i]==3?ft.wDayOfWeek:attr[i]==4?ft.wHour:attr[i]==5?ft.wMinute:
                        attr[i]==6?ft.wSecond:-1);
            attr[i] = (T)res;
          }
        } else _cimg_fdate_err();
      } else _cimg_fdate_err();
#elif cimg_OS==1
      struct stat st_buf;
      if (!stat(path,&st_buf)) {
        const time_t _ft = st_buf.st_mtime;
        struct tm ft_buf, *const p_ft = cimg::localtime(&_ft,&ft_buf);
        if (p_ft) {
          const struct tm& ft = *p_ft;
          for (unsigned int i = 0; i<nb_attr; ++i) {
            res = (int)(attr[i]==0?ft.tm_year + 1900:attr[i]==1?ft.tm_mon + 1:attr[i]==2?ft.tm_mday:
                        attr[i]==3?ft.tm_wday:attr[i]==4?ft.tm_hour:attr[i]==5?ft.tm_min:
                        attr[i]==6?ft.tm_sec:-1);
            attr[i] = (T)res;
          }
        } else _cimg_fdate_err();
      } else _cimg_fdate_err();
#endif
      cimg::mutex(6,0);
      return res;
    }

    //! Get last write time of a given file or directory (single-attribute version).
    /**
       \param path Specified path to get attributes from.
       \param attr Type of requested time attributes.
                   Can be { 0=year | 1=month | 2=day | 3=day of week | 4=hour | 5=minute | 6=second }
       \return Specified attribute or -1 if an error occurred.
    **/
    inline int fdate(const char *const path, unsigned int attr) {
      int out = (int)attr;
      return fdate(path,&out,1);
    }

    //! Get current local time (multiple-attributes version).
    /**
       \param[in,out] attr Type of requested time attributes.
                           Can be { 0=year | 1=month | 2=day | 3=day of week | 4=hour | 5=minute | 6=second |
                                    7=millisecond }
                           Replaced by read attributes after return (or -1 if an error occurred).
       \param nb_attr Number of attributes to read/write.
       \return Latest read attribute.
    **/
    template<typename T>
    inline int date(T *attr, const unsigned int nb_attr) {
      int res = -1;
      cimg::mutex(6);
#if cimg_OS==2
      SYSTEMTIME st;
      GetLocalTime(&st);
      for (unsigned int i = 0; i<nb_attr; ++i) {
        res = (int)(attr[i]==0?st.wYear:
                    attr[i]==1?st.wMonth:
                    attr[i]==2?st.wDay:
                    attr[i]==3?st.wDayOfWeek:
                    attr[i]==4?st.wHour:
                    attr[i]==5?st.wMinute:
                    attr[i]==6?st.wSecond:
                    attr[i]==7?st.wMilliseconds:-1);
        attr[i] = (T)res;
      }
#else
      struct timeval _st;
      gettimeofday(&_st,0);
      struct tm st_buf, *const st = cimg::localtime(&_st.tv_sec,&st_buf);
      if (st) {
        for (unsigned int i = 0; i<nb_attr; ++i) {
          res = (int)(attr[i]==0?st->tm_year + 1900:
                      attr[i]==1?st->tm_mon + 1:
                      attr[i]==2?st->tm_mday:
                      attr[i]==3?st->tm_wday:
                      attr[i]==4?st->tm_hour:
                      attr[i]==5?st->tm_min:
                      attr[i]==6?st->tm_sec:
                      attr[i]==7?_st.tv_usec/1000:-1);
          attr[i] = (T)res;
        }
      } else for (unsigned int i = 0; i<nb_attr; ++i) attr[i] = (T)-1;
#endif
      cimg::mutex(6,0);
      return res;
    }

    //! Get current local time (single-attribute version).
    /**
       \param attr Type of requested time attribute.
                   Can be { 0=year | 1=month | 2=day | 3=day of week | 4=hour | 5=minute | 6=second |
                            7=millisecond }
       \return Specified attribute or -1 if an error occurred.
    **/
    inline int date(unsigned int attr) {
      int out = (int)attr;
      return date(&out,1);
    }

    //! Convert date to epoch (UTC time).
    // 'year' must be >=1900, 'month' in [ 1,12 ], 'day' in [ 1,31 ], 'hour' in [ 0,23 ],
    // 'minute' in [ 0,59 ] and 'second' in [ 0,60 ].
    inline cimg_int64 epoch(const int year, const int month=1,
                            const int day=1, const int hour=0,
                            const int minute=0, const int second=0) {
      static const int tab_days[] = { 31,28,31,30,31,30,31,31,30,31,30,31 };
#define cimg_is_leap(y) ((!((y)%4) && ((y)%100)) || !((y)%400))
#define cimg_days_in_month(y,m) ((m)==2 && cimg_is_leap(y)?29:tab_days[cimg::cut(m,1,12) - 1])
      cimg_int64 days = 0;
      if (year>=1970) for (int y = 1970; y<year; ++y) days+=cimg_is_leap(y)?366:365;
      else for (int y = year; y<1970; ++y) days-=cimg_is_leap(y)?366:365;
      for (int m = 1; m<month; ++m) days+=cimg_days_in_month(year,m);
      days+=day - 1;
      return days*86400 + hour*3600 + minute*60 + second;
    }

    // Get/set path to the \c curl binary.
    inline const char *curl_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the \c dcraw binary.
    inline const char *dcraw_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the FFMPEG's \c ffmpeg binary.
    inline const char *ffmpeg_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the GraphicsMagick's \c gm binary.
    inline const char* graphicsmagick_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the \c gunzip binary.
    inline const char *gunzip_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the \c gzip binary.
    inline const char *gzip_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the ImageMagick's \c convert binary.
    inline const char* imagemagick_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the Medcon's \c medcon binary.
    inline const char* medcon_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to store temporary files.
    inline const char* temporary_path(const char *const user_path=0, const bool reinit_path=false);

    // Get/set path to the \c wget binary.
    inline const char *wget_path(const char *const user_path=0, const bool reinit_path=false);

#if cimg_OS==2
    // Get/set path to the \c powershell binary.
    inline const char *powershell_path(const char *const user_path=0, const bool reinit_path=false);
#endif

#if cimg_OS==1
    inline bool posix_searchpath(const char *file);
#endif

    //! Split filename into two C-strings \c body and \c extension.
    /**
       filename and body must not overlap!
    **/
    inline const char *split_filename(const char *const filename, char *const body=0) {
      if (!filename) { if (body) *body = 0; return ""; }
      const char * p = std::strrchr(filename,'.');
      if (!p || std::strchr(p,'/') || std::strchr(p,'\\')) { // No extension
        if (body) std::strcpy(body,filename);
        return filename + std::strlen(filename);
      }
      const unsigned int l = (unsigned int)(p - filename);
      if (body) { if (l) std::memcpy(body,filename,l); body[l] = 0; }
      return p + 1;
    }

    // Generate a numbered version of a filename.
    inline char* number_filename(const char *const filename, const int number,
                                 const unsigned int digits, char *const str);

    //! Read data from file.
    /**
       \param[out] ptr Pointer to memory buffer that will contain the binary data read from file.
       \param nmemb Number of elements to read.
       \param stream File to read data from.
       \return Number of read elements.
       \note Same as <tt>std::fread()</tt> but may display warning message if all elements could not be read.
    **/
    template<typename T>
    inline size_t fread(T *const ptr, const size_t nmemb, std::FILE *stream) {
      if (!ptr || !stream)
        throw CImgArgumentException("cimg::fread(): Invalid request for reading %lu %s%s from file %p to buffer %p.",
                                    (unsigned long)nmemb,cimg::type<T>::string(),nmemb>1?"s":"",stream,ptr);
      if (!nmemb) return 0;
      const size_t wlimitT = 63*1024*1024, wlimit = wlimitT/sizeof(T);
      size_t to_read = nmemb, al_read = 0, l_to_read = 0, l_al_read = 0;
      do {
        l_to_read = (to_read*sizeof(T))<wlimitT?to_read:wlimit;
        l_al_read = std::fread((void*)(ptr + al_read),sizeof(T),l_to_read,stream);
        al_read+=l_al_read;
        to_read-=l_al_read;
      } while (l_to_read==l_al_read && to_read>0);
      if (to_read>0)
        warn("cimg::fread(): Only %lu/%lu elements could be read from file.",
             (unsigned long)al_read,(unsigned long)nmemb);
      return al_read;
    }

    //! Write data to file.
    /**
       \param ptr Pointer to memory buffer containing the binary data to write on file.
       \param nmemb Number of elements to write.
       \param[out] stream File to write data on.
       \return Number of written elements.
       \note Similar to <tt>std::fwrite</tt> but may display warning messages if all elements could not be written.
    **/
    template<typename T>
    inline size_t fwrite(const T *ptr, const size_t nmemb, std::FILE *stream) {
      if (!ptr || !stream)
        throw CImgArgumentException("cimg::fwrite(): Invalid request for writing %lu %s%s from buffer %p to file %p.",
                                    (unsigned long)nmemb,cimg::type<T>::string(),nmemb>1?"s":"",ptr,stream);
      if (!nmemb) return 0;
      const size_t wlimitT = 63*1024*1024, wlimit = wlimitT/sizeof(T);
      size_t to_write = nmemb, al_write = 0, l_to_write = 0, l_al_write = 0;
      do {
        l_to_write = (to_write*sizeof(T))<wlimitT?to_write:wlimit;
        l_al_write = std::fwrite((void*)(ptr + al_write),sizeof(T),l_to_write,stream);
        al_write+=l_al_write;
        to_write-=l_al_write;
      } while (l_to_write==l_al_write && to_write>0);
      if (to_write>0)
        warn("cimg::fwrite(): Only %lu/%lu elements could be written in file.",
             (unsigned long)al_write,(unsigned long)nmemb);
      return al_write;
    }

    //! Create an empty file.
    /**
       \param file Input file (can be \c 0 if \c filename is set).
       \param filename Filename, as a C-string (can be \c 0 if \c file is set).
    **/
    inline void fempty(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException("cimg::fempty(): Specified filename is (null).");
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      if (!file) cimg::fclose(nfile);
    }

    // Try to guess the format of an image file.
    inline const char *ftype(std::FILE *const file, const char *const filename);

    // Load a file from network as a local temporary file.
    inline char *load_network(const char *const url, char *const filename_local,
                              const unsigned int timeout=0, const bool try_fallback=false,
                              const char *const referer=0, const char *const user_agent=0);

    //! Return options specified on the command line.
    inline const char* option(const char *const name, const int argc, const char *const *const argv,
                              const char *const _default, const char *const usage, const bool reset_static) {
      static bool first = true, visu = false;
      if (reset_static) { first = true; return 0; }
      const char *res = 0;
      if (first) {
        first = false;
        visu = cimg::option("-h",argc,argv,(char*)0,(char*)0,false)!=0;
        visu|=cimg::option("-help",argc,argv,(char*)0,(char*)0,false)!=0;
        visu|=cimg::option("--help",argc,argv,(char*)0,(char*)0,false)!=0;
      }
      if (!name && visu) {
        if (usage) {
          std::fprintf(cimg::output(),"\n %s%s%s",cimg::t_red(),cimg::basename(argv[0]),cimg::t_normal());
          std::fprintf(cimg::output(),": %s",usage);
          std::fprintf(cimg::output()," (%s, %s)\n\n",cimg_date,cimg_time);
        }
        if (_default) std::fprintf(cimg::output(),"%s\n",_default);
      }
      if (name) {
        if (argc>0) {
          int k = 0;
          while (k<argc && std::strcmp(argv[k],name)) ++k;
          res = (k++==argc?_default:(k==argc?argv[--k]:argv[k]));
        } else res = _default;
        if (visu && usage) std::fprintf(cimg::output(),"    %s%-16s%s %-24s %s%s%s\n",
                                        cimg::t_bold(),name,cimg::t_normal(),res?res:"0",
                                        cimg::t_green(),usage,cimg::t_normal());
      }
      return res;
    }

    inline const char* option(const char *const name, const int argc, const char *const *const argv,
                              const char *const _default, const char *const usage=0) {
      return option(name,argc,argv,_default,usage,false);
    }

    inline bool option(const char *const name, const int argc, const char *const *const argv,
                       const bool _default, const char *const usage=0) {
      const char *const s = cimg::option(name,argc,argv,(char*)0);
      const bool res = s?(cimg::strcasecmp(s,"false") && cimg::strcasecmp(s,"off") && cimg::strcasecmp(s,"0")):_default;
      cimg::option(name,0,0,res?"true":"false",usage);
      return res;
    }

    inline int option(const char *const name, const int argc, const char *const *const argv,
                      const int _default, const char *const usage=0) {
      const char *const s = cimg::option(name,argc,argv,(char*)0);
      const int res = s?std::atoi(s):_default;
      char *const tmp = new char[256];
      cimg_snprintf(tmp,256,"%d",res);
      cimg::option(name,0,0,tmp,usage);
      delete[] tmp;
      return res;
    }

    inline char option(const char *const name, const int argc, const char *const *const argv,
                       const char _default, const char *const usage=0) {
      const char *const s = cimg::option(name,argc,argv,(char*)0);
      const char res = s?*s:_default;
      char tmp[8];
      *tmp = res; tmp[1] = 0;
      cimg::option(name,0,0,tmp,usage);
      return res;
    }

    inline float option(const char *const name, const int argc, const char *const *const argv,
                        const float _default, const char *const usage=0) {
      const char *const s = cimg::option(name,argc,argv,(char*)0);
      const float res = s?(float)cimg::atof(s):_default;
      char *const tmp = new char[256];
      cimg_snprintf(tmp,256,"%g",res);
      cimg::option(name,0,0,tmp,usage);
      delete[] tmp;
      return res;
    }

    inline double option(const char *const name, const int argc, const char *const *const argv,
                         const double _default, const char *const usage=0) {
      const char *const s = cimg::option(name,argc,argv,(char*)0);
      const double res = s?cimg::atof(s):_default;
      char *const tmp = new char[256];
      cimg_snprintf(tmp,256,"%g",res);
      cimg::option(name,0,0,tmp,usage);
      delete[] tmp;
      return res;
    }

    //! Print information about \CImg environment variables.
    /**
       \note Output is done on the default output stream.
    **/
    inline void info() {
      std::fprintf(cimg::output(),"\n %s%sCImg Library %u.%u.%u%s, compiled %s ( %s ) with the following flags:\n\n",
                   cimg::t_red(),cimg::t_bold(),cimg_version/100,(cimg_version/10)%10,cimg_version%10,
                   cimg::t_normal(),cimg_date,cimg_time);

      std::fprintf(cimg::output(),"  > Operating System:         %s%-13s%s %s('cimg_OS'=%d)%s\n",
                   cimg::t_bold(),
                   cimg_OS==1?"Unix":(cimg_OS==2?"Windows":"Unknown"),
                   cimg::t_normal(),cimg::t_green(),
                   cimg_OS,
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > CPU endianness:           %s%s Endian%s\n",
                   cimg::t_bold(),
                   cimg::endianness()?"Big":"Little",
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Verbosity mode:           %s%-13s%s %s('cimg_verbosity'=%d)%s\n",
                   cimg::t_bold(),
                   cimg_verbosity==0?"Quiet":
                   cimg_verbosity==1?"Console":
                   cimg_verbosity==2?"Dialog":
                   cimg_verbosity==3?"Console+Warnings":"Dialog+Warnings",
                   cimg::t_normal(),cimg::t_green(),
                   cimg_verbosity,
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Strict warnings:          %s%-13s%s %s('cimg_strict_warnings' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_strict_warnings
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Support for C++11:        %s%-13s%s %s('cimg_use_cpp11'=%d)%s\n",
                   cimg::t_bold(),
                   cimg_use_cpp11?"Yes":"No",
                   cimg::t_normal(),cimg::t_green(),
                   (int)cimg_use_cpp11,
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Using VT100 messages:     %s%-13s%s %s('cimg_use_vt100' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_vt100
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Display type:             %s%-13s%s %s('cimg_display'=%d)%s\n",
                   cimg::t_bold(),
                   cimg_display==0?"No display":
                   cimg_display==1?"X11":
                   cimg_display==2?"Windows GDI":
                   cimg_display==3?"SDL3":"Unknown",
                   cimg::t_normal(),cimg::t_green(),
                   (int)cimg_display,
                   cimg::t_normal());

#if cimg_display==1
      std::fprintf(cimg::output(),"  > Using XShm for X11:       %s%-13s%s %s('cimg_use_xshm' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_xshm
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Using XRand for X11:      %s%-13s%s %s('cimg_use_xrandr' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_xrandr
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());
#endif
      std::fprintf(cimg::output(),"  > Using OpenMP:             %s%-13s%s %s('cimg_use_openmp' %s)%s\n",
                   cimg::t_bold(),
#if cimg_use_openmp!=0
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());
      std::fprintf(cimg::output(),"  > Using PNG library:        %s%-13s%s %s('cimg_use_png' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_png
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());
      std::fprintf(cimg::output(),"  > Using JPEG library:       %s%-13s%s %s('cimg_use_jpeg' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_jpeg
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Using TIFF library:       %s%-13s%s %s('cimg_use_tiff' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_tiff
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Using Magick++ library:   %s%-13s%s %s('cimg_use_magick' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_magick
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      std::fprintf(cimg::output(),"  > Using FFTW3 library:      %s%-13s%s %s('cimg_use_fftw3' %s)%s\n",
                   cimg::t_bold(),
#ifdef cimg_use_fftw3
                   "Yes",cimg::t_normal(),cimg::t_green(),"defined",
#else
                   "No",cimg::t_normal(),cimg::t_green(),"undefined",
#endif
                   cimg::t_normal());

      char *const tmp = new char[1024];

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::curl_path());
      std::fprintf(cimg::output(),"  > Path of 'curl':           %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::dcraw_path());
      std::fprintf(cimg::output(),"  > Path of 'dcraw':          %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::ffmpeg_path());
      std::fprintf(cimg::output(),"  > Path of 'ffmpeg':         %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::graphicsmagick_path());
      std::fprintf(cimg::output(),"  > Path of 'graphicsmagick': %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::gunzip_path());
      std::fprintf(cimg::output(),"  > Path of 'gunzip':         %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::gzip_path());
      std::fprintf(cimg::output(),"  > Path of 'gzip':           %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::imagemagick_path());
      std::fprintf(cimg::output(),"  > Path of 'imagemagick':    %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::medcon_path());
      std::fprintf(cimg::output(),"  > Path of 'medcon':         %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::temporary_path());
      std::fprintf(cimg::output(),"  > Temporary path:           %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());

      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::wget_path());
      std::fprintf(cimg::output(),"  > Path of 'wget':           %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());
#if cimg_OS==2
      cimg_snprintf(tmp,1024,"\"%.1020s\"",cimg::powershell_path());
      std::fprintf(cimg::output(),"  > Path of 'powershell':     %s%-13s%s\n",
                   cimg::t_bold(),
                   tmp,
                   cimg::t_normal());
#endif

      std::fprintf(cimg::output(),"\n");
      delete[] tmp;
    }

  } // namespace cimg { ...

  /*------------------------------------------------
   #
   #
   #   Definition of mathematical operators and
   #   external functions.
   #
   #
   -------------------------------------------------*/

#define _cimg_create_operator(typ) \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator+(const typ val, const CImg<T>& img) { \
    return img.operator+(val); \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator-(const typ val, const CImg<T>& img) { \
    typedef typename cimg::superset<T,typ>::type Tt; \
    return CImg<Tt>(img._width,img._height,img._depth,img._spectrum,val)-=img; \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator*(const typ val, const CImg<T>& img) { \
    return img.operator*(val); \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator/(const typ val, const CImg<T>& img) { \
    return val*img.get_invert(); \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator&(const typ val, const CImg<T>& img) { \
    return img.operator&(val); \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator|(const typ val, const CImg<T>& img) { \
    return img.operator|(val); \
  } \
  template<typename T> \
  inline CImg<typename cimg::superset<T,typ>::type> operator^(const typ val, const CImg<T>& img) { \
    return img.operator^(val); \
  } \
  template<typename T> \
  inline bool operator==(const typ val, const CImg<T>& img) {   \
    return img.operator==(val); \
  } \
  template<typename T> \
  inline bool operator!=(const typ val, const CImg<T>& img) { \
    return img.operator!=(val); \
  }

  _cimg_create_operator(bool)
  _cimg_create_operator(unsigned char)
  _cimg_create_operator(char)
  _cimg_create_operator(signed char)
  _cimg_create_operator(unsigned short)
  _cimg_create_operator(short)
  _cimg_create_operator(unsigned int)
  _cimg_create_operator(int)
  _cimg_create_operator(cimg_uint64)
  _cimg_create_operator(cimg_int64)
  _cimg_create_operator(float)
  _cimg_create_operator(double)
  _cimg_create_operator(long double)

  template<typename T>
  inline CImg<_cimg_Tfloat> operator+(const char *const expression, const CImg<T>& img) {
    return img + expression;
  }

  template<typename T>
  inline CImg<_cimg_Tfloat> operator-(const char *const expression, const CImg<T>& img) {
    return CImg<_cimg_Tfloat>(img,false).fill(expression,true)-=img;
  }

  template<typename T>
  inline CImg<_cimg_Tfloat> operator*(const char *const expression, const CImg<T>& img) {
    return img*expression;
  }

  template<typename T>
  inline CImg<_cimg_Tfloat> operator/(const char *const expression, const CImg<T>& img) {
    return expression*img.get_invert();
  }

  template<typename T>
  inline CImg<T> operator&(const char *const expression, const CImg<T>& img) {
    return img & expression;
  }

  template<typename T>
  inline CImg<T> operator|(const char *const expression, const CImg<T>& img) {
    return img | expression;
  }

  template<typename T>
  inline CImg<T> operator^(const char *const expression, const CImg<T>& img) {
    return img ^ expression;
  }

  template<typename T>
  inline bool operator==(const char *const expression, const CImg<T>& img) {
    return img==expression;
  }

  template<typename T>
  inline bool operator!=(const char *const expression, const CImg<T>& img) {
    return img!=expression;
  }

  template<typename T>
  inline CImg<T> transpose(const CImg<T>& instance) {
    return instance.get_transpose();
  }

  template<typename T>
  inline CImg<_cimg_Tfloat> invert(const CImg<T>& instance) {
    return instance.get_invert();
  }

#define _cimg_create_pointwise_function(name) \
  template<typename T> \
  inline CImg<_cimg_Tfloat> name(const CImg<T>& instance) { \
    return instance.get_##name(); \
  }

  _cimg_create_pointwise_function(abs)
  _cimg_create_pointwise_function(acos)
  _cimg_create_pointwise_function(acosh)
  _cimg_create_pointwise_function(asin)
  _cimg_create_pointwise_function(asinh)
  _cimg_create_pointwise_function(atan)
  _cimg_create_pointwise_function(atanh)
  _cimg_create_pointwise_function(cos)
  _cimg_create_pointwise_function(cosh)
  _cimg_create_pointwise_function(erf)
  _cimg_create_pointwise_function(exp)
  _cimg_create_pointwise_function(log)
  _cimg_create_pointwise_function(log2)
  _cimg_create_pointwise_function(log10)
  _cimg_create_pointwise_function(sqr)
  _cimg_create_pointwise_function(sqrt)
  _cimg_create_pointwise_function(sign)
  _cimg_create_pointwise_function(sin)
  _cimg_create_pointwise_function(sinc)
  _cimg_create_pointwise_function(sinh)
  _cimg_create_pointwise_function(tan)
  _cimg_create_pointwise_function(tanh)

  /*-----------------------------------
   #
   # Define the CImgDisplay structure
   #
   ----------------------------------*/
  //! Allow the creation of windows, display images on them and manage user events (keyboard, mouse and windows events).
  /**
     CImgDisplay functions rely on a low-level graphic library to perform: it can be either \b X-Window
     (X11, for Unix-based systems) or \b GDI32 (for Windows-based systems).
     If both libraries are missing, CImgDisplay will not be able to display images on screen, and will enter
     a minimal mode where warning messages will be outputted each time the program is trying to call one of the
     CImgDisplay function.

     The configuration variable \c cimg_display indicates the graphic library used.
     It is set automatically by \CImg when one of these graphic libraries has been detected.
     But, you can override its value if necessary. Valid choices are:
     - 0: Disable display capabilities.
     - 1: Use \b X-Window (X11) library.
     - 2: Use \b GDI32 library.

     Remember to link your program against \b X11 or \b GDI32 libraries if you use CImgDisplay.
  **/
  struct CImgDisplay {
    cimg_uint64 _timer, _fps_frames, _fps_timer;
    unsigned int _width, _height, _normalization;
    float _fps_fps, _min, _max;
    bool _is_fullscreen;
    char *_title;
    unsigned int _window_width, _window_height, _button, _keys[128], _released_keys[128];

    int _window_x, _window_y, _mouse_x, _mouse_y, _wheel;
    bool _is_closed, _is_resized, _is_moved, _is_event,
      _is_keyESC, _is_keyF1, _is_keyF2, _is_keyF3, _is_keyF4, _is_keyF5, _is_keyF6, _is_keyF7,
      _is_keyF8, _is_keyF9, _is_keyF10, _is_keyF11, _is_keyF12, _is_keyPAUSE, _is_key1, _is_key2,
      _is_key3, _is_key4, _is_key5, _is_key6, _is_key7, _is_key8, _is_key9, _is_key0,
      _is_keyBACKSPACE, _is_keyINSERT, _is_keyHOME, _is_keyPAGEUP, _is_keyTAB, _is_keyQ, _is_keyW, _is_keyE,
      _is_keyR, _is_keyT, _is_keyY, _is_keyU, _is_keyI, _is_keyO, _is_keyP, _is_keyDELETE,
      _is_keyEND, _is_keyPAGEDOWN, _is_keyCAPSLOCK, _is_keyA, _is_keyS, _is_keyD, _is_keyF, _is_keyG,
      _is_keyH, _is_keyJ, _is_keyK, _is_keyL, _is_keyRETURN, _is_keySHIFTLEFT, _is_keyZ, _is_keyX,
      _is_keyC, _is_keyV, _is_keyB, _is_keyN, _is_keyM, _is_keySHIFTRIGHT, _is_keyARROWUP, _is_keyCTRLLEFT,
      _is_keyAPPLEFT, _is_keyALT, _is_keySPACE, _is_keyALTGR, _is_keyAPPRIGHT, _is_keyMENU, _is_keyCTRLRIGHT,
      _is_keyARROWLEFT, _is_keyARROWDOWN, _is_keyARROWRIGHT, _is_keyPAD0, _is_keyPAD1, _is_keyPAD2, _is_keyPAD3,
      _is_keyPAD4, _is_keyPAD5, _is_keyPAD6, _is_keyPAD7, _is_keyPAD8, _is_keyPAD9, _is_keyPADADD, _is_keyPADSUB,
      _is_keyPADMUL, _is_keyPADDIV, _is_keyENTER;

    //@}
    //---------------------------
    //
    //! \name Plugins
    //@{
    //---------------------------

#ifdef cimgdisplay_plugin
#include cimgdisplay_plugin
#endif
#ifdef cimgdisplay_plugin1
#include cimgdisplay_plugin1
#endif
#ifdef cimgdisplay_plugin2
#include cimgdisplay_plugin2
#endif
#ifdef cimgdisplay_plugin3
#include cimgdisplay_plugin3
#endif
#ifdef cimgdisplay_plugin4
#include cimgdisplay_plugin4
#endif
#ifdef cimgdisplay_plugin5
#include cimgdisplay_plugin5
#endif
#ifdef cimgdisplay_plugin6
#include cimgdisplay_plugin6
#endif
#ifdef cimgdisplay_plugin7
#include cimgdisplay_plugin7
#endif
#ifdef cimgdisplay_plugin8
#include cimgdisplay_plugin8
#endif

    //@}
    //--------------------------------------------------------
    //
    //! \name Constructors / Destructor / Instance Management
    //@{
    //--------------------------------------------------------

    //! Destructor.
    /**
       \note If the associated window is visible on the screen, it is closed by the call to the destructor.
    **/
    ~CImgDisplay() {
      assign();
    }

    //! Construct an empty display.
    /**
       \note Constructing an empty CImgDisplay instance does not make a window appearing on the screen, until
       display of valid data is performed.
       \par Example
       \code
       CImgDisplay disp; // Does actually nothing
       ...
       disp.display(img); // Construct new window and display image in it
       \endcode
    **/
    CImgDisplay():
      _width(0),_height(0),_normalization(0),
      _min(0),_max(0),
      _is_fullscreen(false),
      _title(0),
      _window_width(0),_window_height(0),_button(0),
      _window_x(cimg::type<int>::min()),_window_y(cimg::type<int>::min()),
      _mouse_x(-1),_mouse_y(-1),_wheel(0),
      _is_closed(true),_is_resized(false),_is_moved(false),_is_event(false) {
      assign();
    }

    //! Construct a display with specified dimensions.
    /** \param width Window width.
        \param height Window height.
        \param title Window title.
        \param normalization Normalization type
        (<tt>0</tt>=none, <tt>1</tt>=always, <tt>2</tt>=once, <tt>3</tt>=pixel type-dependent, see normalization()).
        \param is_fullscreen Indicates whether fullscreen mode is enabled.
        \param is_closed Indicates whether associated window is initially visible.
        \note A black background is initially displayed on the associated window.
    **/
    CImgDisplay(const unsigned int width, const unsigned int height,
                const char *const title=0, const unsigned int normalization=3,
                const bool is_fullscreen=false, const bool is_closed=false):
      _width(0),_height(0),_normalization(0),
      _min(0),_max(0),
      _is_fullscreen(false),
      _title(0),
      _window_width(0),_window_height(0),_button(0),
      _window_x(cimg::type<int>::min()),_window_y(cimg::type<int>::min()),
      _mouse_x(-1),_mouse_y(-1),_wheel(0),
      _is_closed(true),_is_resized(false),_is_moved(false),_is_event(false) {
      assign(width,height,title,normalization,is_fullscreen,is_closed);
    }

    //! Construct a display from an image.
    /** \param img Image used as a model to create the window.
        \param title Window title.
        \param normalization Normalization type
        (<tt>0</tt>=none, <tt>1</tt>=always, <tt>2</tt>=once, <tt>3</tt>=pixel type-dependent, see normalization()).
        \param is_fullscreen Indicates whether fullscreen mode is enabled.
        \param is_closed Indicates whether associated window is initially visible.
        \note The pixels of the input image are initially displayed on the associated window.
    **/
    template<typename T>
    explicit CImgDisplay(const CImg<T>& img,
                         const char *const title=0, const unsigned int normalization=3,
                         const bool is_fullscreen=false, const bool is_closed=false):
      _width(0),_height(0),_normalization(0),
      _min(0),_max(0),
      _is_fullscreen(false),
      _title(0),
      _window_width(0),_window_height(0),_button(0),
      _window_x(cimg::type<int>::min()),_window_y(cimg::type<int>::min()),
      _mouse_x(-1),_mouse_y(-1),_wheel(0),
      _is_closed(true),_is_resized(false),_is_moved(false),_is_event(false) {
      assign(img,title,normalization,is_fullscreen,is_closed);
    }

    //! Construct a display from an image list.
    /** \param list The images list to display.
        \param title Window title.
        \param normalization Normalization type
        (<tt>0</tt>=none, <tt>1</tt>=always, <tt>2</tt>=once, <tt>3</tt>=pixel type-dependent, see normalization()).
        \param is_fullscreen Indicates whether fullscreen mode is enabled.
        \param is_closed Indicates whether associated window is initially visible.
        \note All images of the list, appended along the X-axis, are initially displayed on the associated window.
    **/
    template<typename T>
    explicit CImgDisplay(const CImgList<T>& list,
                         const char *const title=0, const unsigned int normalization=3,
                         const bool is_fullscreen=false, const bool is_closed=false):
      _width(0),_height(0),_normalization(0),
      _min(0),_max(0),
      _is_fullscreen(false),
      _title(0),
      _window_width(0),_window_height(0),_button(0),
      _window_x(cimg::type<int>::min()),_window_y(cimg::type<int>::min()),
      _mouse_x(-1),_mouse_y(-1),_wheel(0),
      _is_closed(true),_is_resized(false),_is_moved(false),_is_event(false) {
      assign(list,title,normalization,is_fullscreen,is_closed);
    }

    //! Construct a display as a copy of an existing one.
    /**
        \param disp Display instance to copy.
        \note The pixel buffer of the input window is initially displayed on the associated window.
    **/
    CImgDisplay(const CImgDisplay& disp):
      _width(0),_height(0),_normalization(0),
      _min(0),_max(0),
      _is_fullscreen(false),
      _title(0),
      _window_width(0),_window_height(0),_button(0),
      _window_x(cimg::type<int>::min()),_window_y(cimg::type<int>::min()),
      _mouse_x(-1),_mouse_y(-1),_wheel(0),
      _is_closed(true),_is_resized(false),_is_moved(false),_is_event(false) {
      assign(disp);
    }

    //! Take a screenshot.
    /**
       \param[out] img Output screenshot. Can be empty on input
    **/
    template<typename T>
    static void screenshot(CImg<T>& img) {
      return screenshot(0,0,cimg::type<int>::max(),cimg::type<int>::max(),img);
    }

#if cimg_display==0

    static void _no_display_exception() {
      throw CImgDisplayException("CImgDisplay(): No display available.");
    }

    //! Destructor - Empty constructor \inplace.
    /**
       \note Replace the current instance by an empty display.
    **/
    CImgDisplay& assign() {
      return flush();
    }

    //! Construct a display with specified dimensions \inplace.
    /**
    **/
    CImgDisplay& assign(const unsigned int width, const unsigned int height,
                        const char *const title=0, const unsigned int normalization=3,
                        const bool is_fullscreen=false, const bool is_closed=false) {
      cimg::unused(width,height,title,normalization,is_fullscreen,is_closed);
      _no_display_exception();
      return assign();
    }

    //! Construct a display from an image \inplace.
    /**
    **/
    template<typename T>
    CImgDisplay& assign(const CImg<T>& img,
                        const char *const title=0, const unsigned int normalization=3,
                        const bool is_fullscreen=false, const bool is_closed=false) {
      _no_display_exception();
      return assign(img._width,img._height,title,normalization,is_fullscreen,is_closed);
    }

    //! Construct a display from an image list \inplace.
    /**
    **/
    template<typename T>
    CImgDisplay& assign(const CImgList<T>& list,
                        const char *const title=0, const unsigned int normalization=3,
                        const bool is_fullscreen=false, const bool is_closed=false) {
      _no_display_exception();
      return assign(list._width,list._width,title,normalization,is_fullscreen,is_closed);
    }

    //! Construct a display as a copy of another one \inplace.
    /**
    **/
    CImgDisplay& assign(const CImgDisplay &disp) {
      _no_display_exception();
      return assign(disp._width,disp._height);
    }

#endif

    //! Return a reference to an empty display.
    /**
       \note Can be useful for writing function prototypes where one of the argument (of type CImgDisplay&)
       must have a default value.
       \par Example
       \code
       void foo(CImgDisplay& disp=CImgDisplay::empty());
       \endcode
    **/
    static CImgDisplay& empty() {
      static CImgDisplay _empty;
      return _empty.assign();
    }

    //! Return a reference to an empty display \const.
    static const CImgDisplay& const_empty() {
      static const CImgDisplay _empty;
      return _empty;
    }

#define cimg_fitscreen(dx,dy,dz) CImgDisplay::_fitscreen(dx,dy,dz,-25,-85,false), \
                                 CImgDisplay::_fitscreen(dx,dy,dz,-25,-85,true)
    static unsigned int _fitscreen(const unsigned int dx, const unsigned int dy, const unsigned int dz,
                                   const int dmin, const int dmax, const bool return_y) {
      const int
        u = CImgDisplay::screen_width(),
        v = CImgDisplay::screen_height();
      const float
        mw = dmin<0?cimg::round(u*-dmin/100.f):(float)dmin,
        mh = dmin<0?cimg::round(v*-dmin/100.f):(float)dmin,
        Mw = dmax<0?cimg::round(u*-dmax/100.f):(float)dmax,
        Mh = dmax<0?cimg::round(v*-dmax/100.f):(float)dmax;
      float
        w = (float)std::max(1U,dx),
        h = (float)std::max(1U,dy);
      if (dz>1) { w+=dz; h+=dz; }
      if (w<mw) { h = h*mw/w; w = mw; }
      if (h<mh) { w = w*mh/h; h = mh; }
      if (w>Mw) { h = h*Mw/w; w = Mw; }
      if (h>Mh) { w = w*Mh/h; h = Mh; }
      if (w<mw) w = mw;
      if (h<mh) h = mh;
      return std::max(1U,(unsigned int)cimg::round(return_y?h:w));
    }

    //@}
    //------------------------------------------
    //
    //! \name Overloaded Operators
    //@{
    //------------------------------------------

    //! Display image on associated window.
    /**
       \note <tt>disp = img</tt> is equivalent to <tt>disp.display(img)</tt>.
    **/
    template<typename t>
    CImgDisplay& operator=(const CImg<t>& img) {
      return display(img);
    }

    //! Display list of images on associated window.
    /**
       \note <tt>disp = list</tt> is equivalent to <tt>disp.display(list)</tt>.
    **/
    template<typename t>
    CImgDisplay& operator=(const CImgList<t>& list) {
      return display(list);
    }

    //! Construct a display as a copy of another one \inplace.
    /**
       \note Equivalent to assign(const CImgDisplay&).
     **/
    CImgDisplay& operator=(const CImgDisplay& disp) {
      if (this==&disp) return *this;
      return assign(disp);
    }

    //! Return \c false if display is empty, \c true otherwise.
    /**
       \note <tt>if (disp) { ... }</tt> is equivalent to <tt>if (!disp.is_empty()) { ... }</tt>.
    **/
    operator bool() const {
      return !is_empty();
    }

    //@}
    //------------------------------------------
    //
    //! \name Instance Checking
    //@{
    //------------------------------------------

    //! Return \c true if display is empty, \c false otherwise.
    /**
    **/
    bool is_empty() const {
      return !(_width && _height);
    }

    //! Return \c true if display is closed (i.e. not visible on the screen), \c false otherwise.
    /**
       \note
       - When a user physically closes the associated window, the display is set to closed.
       - A closed display is not destroyed. Its associated window can be show again on the screen using show().
    **/
    bool is_closed() const {
      return _is_closed;
    }

    //! Return \c true if display is visible (i.e. not closed by the user), \c false otherwise.
    bool is_visible() const {
      return !is_closed();
    }

    //! Return \c true if associated window has been resized on the screen, \c false otherwise.
    /**
    **/
    bool is_resized() const {
      return _is_resized;
    }

    //! Return \c true if associated window has been moved on the screen, \c false otherwise.
    /**
    **/
    bool is_moved() const {
      return _is_moved;
    }

    //! Return \c true if any event has occurred on the associated window, \c false otherwise.
    /**
    **/
    bool is_event() const {
      return _is_event;
    }

    //! Return \c true if current display is in fullscreen mode, \c false otherwise.
    /**
    **/
    bool is_fullscreen() const {
      return _is_fullscreen;
    }

    //! Return \c true if any key is being pressed on the associated window, \c false otherwise.
    /**
       \note The functions below do the same only for specific keys.
    **/
    bool is_key() const {
      return _is_keyESC || _is_keyF1 || _is_keyF2 || _is_keyF3 ||
        _is_keyF4 || _is_keyF5 || _is_keyF6 || _is_keyF7 ||
        _is_keyF8 || _is_keyF9 || _is_keyF10 || _is_keyF11 ||
        _is_keyF12 || _is_keyPAUSE || _is_key1 || _is_key2 ||
        _is_key3 || _is_key4 || _is_key5 || _is_key6 ||
        _is_key7 || _is_key8 || _is_key9 || _is_key0 ||
        _is_keyBACKSPACE || _is_keyINSERT || _is_keyHOME ||
        _is_keyPAGEUP || _is_keyTAB || _is_keyQ || _is_keyW ||
        _is_keyE || _is_keyR || _is_keyT || _is_keyY ||
        _is_keyU || _is_keyI || _is_keyO || _is_keyP ||
        _is_keyDELETE || _is_keyEND || _is_keyPAGEDOWN ||
        _is_keyCAPSLOCK || _is_keyA || _is_keyS || _is_keyD ||
        _is_keyF || _is_keyG || _is_keyH || _is_keyJ ||
        _is_keyK || _is_keyL || _is_keyRETURN ||
        _is_keySHIFTLEFT || _is_keyZ || _is_keyX || _is_keyC ||
        _is_keyV || _is_keyB || _is_keyN || _is_keyM ||
        _is_keySHIFTRIGHT || _is_keyARROWUP || _is_keyCTRLLEFT ||
        _is_keyAPPLEFT || _is_keyALT || _is_keySPACE || _is_keyALTGR ||
        _is_keyAPPRIGHT || _is_keyMENU || _is_keyCTRLRIGHT ||
        _is_keyARROWLEFT || _is_keyARROWDOWN || _is_keyARROWRIGHT ||
        _is_keyPAD0 || _is_keyPAD1 || _is_keyPAD2 ||
        _is_keyPAD3 || _is_keyPAD4 || _is_keyPAD5 ||
        _is_keyPAD6 || _is_keyPAD7 || _is_keyPAD8 ||
        _is_keyPAD9 || _is_keyPADADD || _is_keyPADSUB ||
        _is_keyPADMUL || _is_keyPADDIV || _is_keyENTER;
    }

    //! Return \c true if key specified by given keycode is being pressed on the associated window, \c false otherwise.
    /**
       \param keycode Keycode to test.
       \note Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
       \par Example
       \code
       CImgDisplay disp(400,400);
       while (!disp.is_closed()) {
         if (disp.key(cimg::keyTAB)) { ... } // Equivalent to 'if (disp.is_keyTAB())'
         disp.wait();
       }
       \endcode
    **/
    bool is_key(const unsigned int keycode) const {
#define _cimg_iskey_test(k) if (keycode==cimg::key##k) return _is_key##k;
      _cimg_iskey_test(ESC); _cimg_iskey_test(F1); _cimg_iskey_test(F2); _cimg_iskey_test(F3);
      _cimg_iskey_test(F4); _cimg_iskey_test(F5); _cimg_iskey_test(F6); _cimg_iskey_test(F7);
      _cimg_iskey_test(F8); _cimg_iskey_test(F9); _cimg_iskey_test(F10); _cimg_iskey_test(F11);
      _cimg_iskey_test(F12); _cimg_iskey_test(PAUSE); _cimg_iskey_test(1); _cimg_iskey_test(2);
      _cimg_iskey_test(3); _cimg_iskey_test(4); _cimg_iskey_test(5); _cimg_iskey_test(6);
      _cimg_iskey_test(7); _cimg_iskey_test(8); _cimg_iskey_test(9); _cimg_iskey_test(0);
      _cimg_iskey_test(BACKSPACE); _cimg_iskey_test(INSERT); _cimg_iskey_test(HOME);
      _cimg_iskey_test(PAGEUP); _cimg_iskey_test(TAB); _cimg_iskey_test(Q); _cimg_iskey_test(W);
      _cimg_iskey_test(E); _cimg_iskey_test(R); _cimg_iskey_test(T); _cimg_iskey_test(Y);
      _cimg_iskey_test(U); _cimg_iskey_test(I); _cimg_iskey_test(O); _cimg_iskey_test(P);
      _cimg_iskey_test(DELETE); _cimg_iskey_test(END); _cimg_iskey_test(PAGEDOWN);
      _cimg_iskey_test(CAPSLOCK); _cimg_iskey_test(A); _cimg_iskey_test(S); _cimg_iskey_test(D);
      _cimg_iskey_test(F); _cimg_iskey_test(G); _cimg_iskey_test(H); _cimg_iskey_test(J);
      _cimg_iskey_test(K); _cimg_iskey_test(L); _cimg_iskey_test(RETURN);
      _cimg_iskey_test(SHIFTLEFT); _cimg_iskey_test(Z); _cimg_iskey_test(X); _cimg_iskey_test(C);
      _cimg_iskey_test(V); _cimg_iskey_test(B); _cimg_iskey_test(N); _cimg_iskey_test(M);
      _cimg_iskey_test(SHIFTRIGHT); _cimg_iskey_test(ARROWUP); _cimg_iskey_test(CTRLLEFT);
      _cimg_iskey_test(APPLEFT); _cimg_iskey_test(ALT); _cimg_iskey_test(SPACE); _cimg_iskey_test(ALTGR);
      _cimg_iskey_test(APPRIGHT); _cimg_iskey_test(MENU); _cimg_iskey_test(CTRLRIGHT);
      _cimg_iskey_test(ARROWLEFT); _cimg_iskey_test(ARROWDOWN); _cimg_iskey_test(ARROWRIGHT);
      _cimg_iskey_test(PAD0); _cimg_iskey_test(PAD1); _cimg_iskey_test(PAD2);
      _cimg_iskey_test(PAD3); _cimg_iskey_test(PAD4); _cimg_iskey_test(PAD5);
      _cimg_iskey_test(PAD6); _cimg_iskey_test(PAD7); _cimg_iskey_test(PAD8);
      _cimg_iskey_test(PAD9); _cimg_iskey_test(PADADD); _cimg_iskey_test(PADSUB);
      _cimg_iskey_test(PADMUL); _cimg_iskey_test(PADDIV); _cimg_iskey_test(ENTER);
      return false;
    }

    //! Return \c true if key specified by given keycode is being pressed on the associated window, \c false otherwise.
    /**
       \param keycode C-string containing the keycode label of the key to test.
       \note Use it when the key you want to test can be dynamically set by the user.
       \par Example
       \code
       CImgDisplay disp(400,400);
       const char *const keycode = "TAB";
       while (!disp.is_closed()) {
         if (disp.is_key(keycode)) { ... } // Equivalent to 'if (disp.is_keyTAB())'
         disp.wait();
       }
       \endcode
    **/
    bool& is_key(const char *const keycode) {
      static bool f = false;
      f = false;
#define _cimg_iskey_test2(k) if (!cimg::strcasecmp(keycode,#k)) return _is_key##k;
      _cimg_iskey_test2(ESC); _cimg_iskey_test2(F1); _cimg_iskey_test2(F2); _cimg_iskey_test2(F3);
      _cimg_iskey_test2(F4); _cimg_iskey_test2(F5); _cimg_iskey_test2(F6); _cimg_iskey_test2(F7);
      _cimg_iskey_test2(F8); _cimg_iskey_test2(F9); _cimg_iskey_test2(F10); _cimg_iskey_test2(F11);
      _cimg_iskey_test2(F12); _cimg_iskey_test2(PAUSE); _cimg_iskey_test2(1); _cimg_iskey_test2(2);
      _cimg_iskey_test2(3); _cimg_iskey_test2(4); _cimg_iskey_test2(5); _cimg_iskey_test2(6);
      _cimg_iskey_test2(7); _cimg_iskey_test2(8); _cimg_iskey_test2(9); _cimg_iskey_test2(0);
      _cimg_iskey_test2(BACKSPACE); _cimg_iskey_test2(INSERT); _cimg_iskey_test2(HOME);
      _cimg_iskey_test2(PAGEUP); _cimg_iskey_test2(TAB); _cimg_iskey_test2(Q); _cimg_iskey_test2(W);
      _cimg_iskey_test2(E); _cimg_iskey_test2(R); _cimg_iskey_test2(T); _cimg_iskey_test2(Y);
      _cimg_iskey_test2(U); _cimg_iskey_test2(I); _cimg_iskey_test2(O); _cimg_iskey_test2(P);
      _cimg_iskey_test2(DELETE); _cimg_iskey_test2(END); _cimg_iskey_test2(PAGEDOWN);
      _cimg_iskey_test2(CAPSLOCK); _cimg_iskey_test2(A); _cimg_iskey_test2(S); _cimg_iskey_test2(D);
      _cimg_iskey_test2(F); _cimg_iskey_test2(G); _cimg_iskey_test2(H); _cimg_iskey_test2(J);
      _cimg_iskey_test2(K); _cimg_iskey_test2(L); _cimg_iskey_test2(RETURN);
      _cimg_iskey_test2(SHIFTLEFT); _cimg_iskey_test2(Z); _cimg_iskey_test2(X); _cimg_iskey_test2(C);
      _cimg_iskey_test2(V); _cimg_iskey_test2(B); _cimg_iskey_test2(N); _cimg_iskey_test2(M);
      _cimg_iskey_test2(SHIFTRIGHT); _cimg_iskey_test2(ARROWUP); _cimg_iskey_test2(CTRLLEFT);
      _cimg_iskey_test2(APPLEFT); _cimg_iskey_test2(ALT); _cimg_iskey_test2(SPACE); _cimg_iskey_test2(ALTGR);
      _cimg_iskey_test2(APPRIGHT); _cimg_iskey_test2(MENU); _cimg_iskey_test2(CTRLRIGHT);
      _cimg_iskey_test2(ARROWLEFT); _cimg_iskey_test2(ARROWDOWN); _cimg_iskey_test2(ARROWRIGHT);
      _cimg_iskey_test2(PAD0); _cimg_iskey_test2(PAD1); _cimg_iskey_test2(PAD2);
      _cimg_iskey_test2(PAD3); _cimg_iskey_test2(PAD4); _cimg_iskey_test2(PAD5);
      _cimg_iskey_test2(PAD6); _cimg_iskey_test2(PAD7); _cimg_iskey_test2(PAD8);
      _cimg_iskey_test2(PAD9); _cimg_iskey_test2(PADADD); _cimg_iskey_test2(PADSUB);
      _cimg_iskey_test2(PADMUL); _cimg_iskey_test2(PADDIV); _cimg_iskey_test2(ENTER);
      return f;
    }

    //! Return \c true if specified key sequence has been typed on the associated window, \c false otherwise.
    /**
       \param keycodes_sequence Buffer of keycodes to test.
       \param length Number of keys in the \c keycodes_sequence buffer.
       \param remove_sequence Indicates whether the key sequence must be removed from the key history, if found.
       \note Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
       \par Example
       \code
       CImgDisplay disp(400,400);
       const unsigned int key_seq[] = { cimg::keyCTRLLEFT, cimg::keyD };
       while (!disp.is_closed()) {
         if (disp.is_key_sequence(key_seq,2)) { ... } // Test for the 'CTRL+D' keyboard event
         disp.wait();
       }
       \endcode
    **/
    bool is_key_sequence(const unsigned int *const keycodes_sequence, const unsigned int length,
                         const bool remove_sequence=false) {
      if (keycodes_sequence && length) {
        const unsigned int
          *const ps_end = keycodes_sequence + length - 1,
          *const pk_end = (unsigned int*)_keys + 1 + 128 - length,
          k = *ps_end;
        for (unsigned int *pk = (unsigned int*)_keys; pk<pk_end; ) {
          if (*(pk++)==k) {
            bool res = true;
            const unsigned int *ps = ps_end, *pk2 = pk;
            for (unsigned int i = 1; i<length; ++i) res = (*(--ps)==*(pk2++));
            if (res) {
              if (remove_sequence) std::memset((void*)(pk - 1),0,sizeof(unsigned int)*length);
              return true;
            }
          }
        }
      }
      return false;
    }

#define _cimg_iskey_def(k) \
    bool is_key##k() const { \
      return _is_key##k; \
    }

    //! Return \c true if the \c ESC key is being pressed on the associated window, \c false otherwise.
    /**
       \note Similar functions exist for all keys managed by \CImg (see cimg::keyESC).
    **/
    _cimg_iskey_def(ESC); _cimg_iskey_def(F1); _cimg_iskey_def(F2); _cimg_iskey_def(F3);
    _cimg_iskey_def(F4); _cimg_iskey_def(F5); _cimg_iskey_def(F6); _cimg_iskey_def(F7);
    _cimg_iskey_def(F8); _cimg_iskey_def(F9); _cimg_iskey_def(F10); _cimg_iskey_def(F11);
    _cimg_iskey_def(F12); _cimg_iskey_def(PAUSE); _cimg_iskey_def(1); _cimg_iskey_def(2);
    _cimg_iskey_def(3); _cimg_iskey_def(4); _cimg_iskey_def(5); _cimg_iskey_def(6);
    _cimg_iskey_def(7); _cimg_iskey_def(8); _cimg_iskey_def(9); _cimg_iskey_def(0);
    _cimg_iskey_def(BACKSPACE); _cimg_iskey_def(INSERT); _cimg_iskey_def(HOME);
    _cimg_iskey_def(PAGEUP); _cimg_iskey_def(TAB); _cimg_iskey_def(Q); _cimg_iskey_def(W);
    _cimg_iskey_def(E); _cimg_iskey_def(R); _cimg_iskey_def(T); _cimg_iskey_def(Y);
    _cimg_iskey_def(U); _cimg_iskey_def(I); _cimg_iskey_def(O); _cimg_iskey_def(P);
    _cimg_iskey_def(DELETE); _cimg_iskey_def(END); _cimg_iskey_def(PAGEDOWN);
    _cimg_iskey_def(CAPSLOCK); _cimg_iskey_def(A); _cimg_iskey_def(S); _cimg_iskey_def(D);
    _cimg_iskey_def(F); _cimg_iskey_def(G); _cimg_iskey_def(H); _cimg_iskey_def(J);
    _cimg_iskey_def(K); _cimg_iskey_def(L); _cimg_iskey_def(RETURN);
    _cimg_iskey_def(SHIFTLEFT); _cimg_iskey_def(Z); _cimg_iskey_def(X); _cimg_iskey_def(C);
    _cimg_iskey_def(V); _cimg_iskey_def(B); _cimg_iskey_def(N); _cimg_iskey_def(M);
    _cimg_iskey_def(SHIFTRIGHT); _cimg_iskey_def(ARROWUP); _cimg_iskey_def(CTRLLEFT);
    _cimg_iskey_def(APPLEFT); _cimg_iskey_def(ALT); _cimg_iskey_def(SPACE); _cimg_iskey_def(ALTGR);
    _cimg_iskey_def(APPRIGHT); _cimg_iskey_def(MENU); _cimg_iskey_def(CTRLRIGHT);
    _cimg_iskey_def(ARROWLEFT); _cimg_iskey_def(ARROWDOWN); _cimg_iskey_def(ARROWRIGHT);
    _cimg_iskey_def(PAD0); _cimg_iskey_def(PAD1); _cimg_iskey_def(PAD2);
    _cimg_iskey_def(PAD3); _cimg_iskey_def(PAD4); _cimg_iskey_def(PAD5);
    _cimg_iskey_def(PAD6); _cimg_iskey_def(PAD7); _cimg_iskey_def(PAD8);
    _cimg_iskey_def(PAD9); _cimg_iskey_def(PADADD); _cimg_iskey_def(PADSUB);
    _cimg_iskey_def(PADMUL); _cimg_iskey_def(PADDIV); _cimg_iskey_def(ENTER);

    //@}
    //------------------------------------------
    //
    //! \name Instance Characteristics
    //@{
    //------------------------------------------

#if cimg_display==0

    //! Return width of the screen (current resolution along the X-axis).
    /**
    **/
    static int screen_width() {
      _no_display_exception();
      return 0;
    }

    //! Return height of the screen (current resolution along the Y-axis).
    /**
    **/
    static int screen_height() {
      _no_display_exception();
      return 0;
    }

#endif

    //! Return display width.
    /**
       \note The width of the display (i.e. the width of the pixel data buffer associated with the CImgDisplay instance)
       may be different from the actual width of the associated window.
    **/
    int width() const {
      return (int)_width;
    }

    //! Return display height.
    /**
       \note The height of the display (i.e. the height of the pixel data buffer associated with the CImgDisplay
         instance) may be different from the actual height of the associated window.
    **/
    int height() const {
      return (int)_height;
    }

    //! Return normalization type of the display.
    /**
       The normalization type indicates how the values of an input image are normalized by the CImgDisplay to be
       correctly displayed. The range of values for pixels displayed on the screen is <tt>[0,255]</tt>.
       If the range of values of the data to display is different, a normalization may be required for displaying
       the data in a correct way. The normalization type can be one of:
       - \c 0: Value normalization is disabled. It is then assumed that all input data to be displayed by the
       CImgDisplay instance have values in range <tt>[0,255]</tt>.
       - \c 1: Value normalization is always performed (this is the default behavior).
       Before displaying an input image, its values will be (virtually) stretched
       in range <tt>[0,255]</tt>, so that the contrast of the displayed pixels will be maximum.
       Use this mode for images whose minimum and maximum values are not prescribed to known values
       (e.g. float-valued images).
       Note that when normalized versions of images are computed for display purposes, the actual values of these
       images are not modified.
       - \c 2: Value normalization is performed once (on the first image display), then the same normalization
       coefficients are kept for next displayed frames.
       - \c 3: Value normalization depends on the pixel type of the data to display. For integer pixel types,
       the normalization is done regarding the minimum/maximum values of the type (no normalization occurs then
       for <tt>unsigned char</tt>).
       For float-valued pixel types, the normalization is done regarding the minimum/maximum value of the image
       data instead.
    **/
    unsigned int normalization() const {
      return _normalization;
    }

    //! Return title of the associated window as a C-string.
    /**
       \note Window title may be not visible, depending on the used window manager or if the current display is
       in fullscreen mode.
    **/
    const char *title() const {
      return _title?_title:"";
    }

    //! Return width of the associated window.
    /**
       \note The width of the display (i.e. the width of the pixel data buffer associated with the CImgDisplay instance)
       may be different from the actual width of the associated window.
    **/
    int window_width() const {
      return (int)_window_width;
    }

    //! Return height of the associated window.
    /**
       \note The height of the display (i.e. the height of the pixel data buffer associated with the CImgDisplay
         instance) may be different from the actual height of the associated window.
    **/
    int window_height() const {
      return (int)_window_height;
    }

    //! Return X-coordinate of the associated window.
    /**
       \note The returned coordinate corresponds to the location of the upper-left corner of the associated window.
    **/
    int window_x() const {
      return _window_x;
    }

    //! Return Y-coordinate of the associated window.
    /**
       \note The returned coordinate corresponds to the location of the upper-left corner of the associated window.
    **/
    int window_y() const {
      return _window_y;
    }

    //! Return X-coordinate of the mouse pointer.
    /**
       \note
       - If the mouse pointer is outside window area, \c -1 is returned.
       - Otherwise, the returned value is in the range [0,width()-1].
    **/
    int mouse_x() const {
      return _mouse_x;
    }

    //! Return Y-coordinate of the mouse pointer.
    /**
       \note
       - If the mouse pointer is outside window area, \c -1 is returned.
       - Otherwise, the returned value is in the range [0,height()-1].
    **/
    int mouse_y() const {
      return _mouse_y;
    }

    //! Return current state of the mouse buttons.
    /**
       \note Three mouse buttons can be managed. If one button is pressed, its corresponding bit in the returned
       value is set:
       - bit \c 0 (value \c 0x1): State of the left mouse button.
       - bit \c 1 (value \c 0x2): State of the right mouse button.
       - bit \c 2 (value \c 0x4): State of the middle mouse button.

       Several bits can be activated if more than one button are pressed at the same time.
       \par Example
       \code
       CImgDisplay disp(400,400);
       while (!disp.is_closed()) {
         if (disp.button()&1) { // Left button clicked
           ...
         }
         if (disp.button()&2) { // Right button clicked
           ...
         }
         if (disp.button()&4) { // Middle button clicked
           ...
         }
         disp.wait();
       }
       \endcode
    **/
    unsigned int button() const {
      return _button;
    }

    //! Return current state of the mouse wheel.
    /**
       \note
       - The returned value can be positive or negative depending on whether the mouse wheel has been scrolled
       forward or backward.
       - Scrolling the wheel forward add \c 1 to the wheel value.
       - Scrolling the wheel backward subtract \c 1 from the wheel value.
       - The returned value cumulates the number of forward of backward scrolls since the creation of the display,
       or since the last reset of the wheel value (using set_wheel()). It is strongly recommended to quickly reset
       the wheel counter when an action has been performed regarding the current wheel value.
       Otherwise, the returned wheel value may be for instance \c 0 despite the fact that many scrolls have been done
       (as many in forward as in backward directions).
       \par Example
       \code
       CImgDisplay disp(400,400);
       while (!disp.is_closed()) {
         if (disp.wheel()) {
           int counter = disp.wheel(); // Read the state of the mouse wheel
           ... // Do what you want with 'counter'
           disp.set_wheel(); // Reset the wheel value to 0
         }
         disp.wait();
       }
       \endcode
    **/
    int wheel() const {
      return _wheel;
    }

    //! Return one entry from the pressed keys history.
    /**
       \param pos Index to read from the pressed keys history (index \c 0 corresponds to latest entry).
       \return Keycode of a pressed key or \c 0 for a released key.
       \note
       - Each CImgDisplay stores a history of the pressed keys in a buffer of size \c 128. When a new key is pressed,
       its keycode is stored in the pressed keys history. When a key is released, \c 0 is put instead.
       This means that up to the 64 last pressed keys may be read from the pressed keys history.
       When a new value is stored, the pressed keys history is shifted so that the latest entry is always
       stored at position \c 0.
       - Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
    **/
    const unsigned int& key(const unsigned int pos=0) const {
      static unsigned int key0;
      return pos<128?_keys[pos]:(key0 = 0);
    }

    //! Return one entry from the released keys history.
    /**
       \param pos Index to read from the released keys history (index \c 0 corresponds to latest entry).
       \return Keycode of a released key or \c 0 for a pressed key.
       \note
       - Each CImgDisplay stores a history of the released keys in a buffer of size \c 128. When a new key is released,
       its keycode is stored in the pressed keys history. When a key is pressed, \c 0 is put instead.
       This means that up to the 64 last released keys may be read from the released keys history.
       When a new value is stored, the released keys history is shifted so that the latest entry is always
       stored at position \c 0.
       - Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
    **/
    const unsigned int& released_key(const unsigned int pos=0) const {
      static unsigned int key0;
      return pos<128?_released_keys[pos]:(key0 = 0);
    }

    //! Return keycode corresponding to the specified string.
    /**
       \note Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
       \par Example
       \code
       const unsigned int keyTAB = CImgDisplay::keycode("TAB"); // Return cimg::keyTAB
       \endcode
    **/
    static unsigned int keycode(const char *const keycode) {
#define _cimg_keycode(k) if (!cimg::strcasecmp(keycode,#k)) return cimg::key##k;
      _cimg_keycode(ESC); _cimg_keycode(F1); _cimg_keycode(F2); _cimg_keycode(F3);
      _cimg_keycode(F4); _cimg_keycode(F5); _cimg_keycode(F6); _cimg_keycode(F7);
      _cimg_keycode(F8); _cimg_keycode(F9); _cimg_keycode(F10); _cimg_keycode(F11);
      _cimg_keycode(F12); _cimg_keycode(PAUSE); _cimg_keycode(1); _cimg_keycode(2);
      _cimg_keycode(3); _cimg_keycode(4); _cimg_keycode(5); _cimg_keycode(6);
      _cimg_keycode(7); _cimg_keycode(8); _cimg_keycode(9); _cimg_keycode(0);
      _cimg_keycode(BACKSPACE); _cimg_keycode(INSERT); _cimg_keycode(HOME);
      _cimg_keycode(PAGEUP); _cimg_keycode(TAB); _cimg_keycode(Q); _cimg_keycode(W);
      _cimg_keycode(E); _cimg_keycode(R); _cimg_keycode(T); _cimg_keycode(Y);
      _cimg_keycode(U); _cimg_keycode(I); _cimg_keycode(O); _cimg_keycode(P);
      _cimg_keycode(DELETE); _cimg_keycode(END); _cimg_keycode(PAGEDOWN);
      _cimg_keycode(CAPSLOCK); _cimg_keycode(A); _cimg_keycode(S); _cimg_keycode(D);
      _cimg_keycode(F); _cimg_keycode(G); _cimg_keycode(H); _cimg_keycode(J);
      _cimg_keycode(K); _cimg_keycode(L); _cimg_keycode(RETURN);
      _cimg_keycode(SHIFTLEFT); _cimg_keycode(Z); _cimg_keycode(X); _cimg_keycode(C);
      _cimg_keycode(V); _cimg_keycode(B); _cimg_keycode(N); _cimg_keycode(M);
      _cimg_keycode(SHIFTRIGHT); _cimg_keycode(ARROWUP); _cimg_keycode(CTRLLEFT);
      _cimg_keycode(APPLEFT); _cimg_keycode(ALT); _cimg_keycode(SPACE); _cimg_keycode(ALTGR);
      _cimg_keycode(APPRIGHT); _cimg_keycode(MENU); _cimg_keycode(CTRLRIGHT);
      _cimg_keycode(ARROWLEFT); _cimg_keycode(ARROWDOWN); _cimg_keycode(ARROWRIGHT);
      _cimg_keycode(PAD0); _cimg_keycode(PAD1); _cimg_keycode(PAD2);
      _cimg_keycode(PAD3); _cimg_keycode(PAD4); _cimg_keycode(PAD5);
      _cimg_keycode(PAD6); _cimg_keycode(PAD7); _cimg_keycode(PAD8);
      _cimg_keycode(PAD9); _cimg_keycode(PADADD); _cimg_keycode(PADSUB);
      _cimg_keycode(PADMUL); _cimg_keycode(PADDIV); _cimg_keycode(ENTER);
      return 0;
    }

    //! Return the current refresh rate, in frames per second.
    /**
       \note Returns a meaningful value when the current instance is used to display successive frames.
       It measures the delay between successive calls to frames_per_second().
    **/
    float frames_per_second() {
      if (!_fps_timer) _fps_timer = cimg::time();
      const float delta = (float)((cimg::time() - _fps_timer)/1000.f);
      ++_fps_frames;
      if (delta>=1) {
        _fps_fps = _fps_frames/delta;
        _fps_frames = 0;
        _fps_timer = cimg::time();
      }
      return _fps_fps;
    }

    // Move the current display window such that its content remains within the current screen.
    CImgDisplay& move_inside_screen() {
      if (is_empty()) return *this;
      const int
        x0 = window_x(),
        y0 = window_y(),
        x1 = x0 + window_width() - 1,
        y1 = y0 + window_height() - 1,
        sw = CImgDisplay::screen_width(),
        sh = CImgDisplay::screen_height();
      if (x0<0 || y0<0 || x1>=sw || y1>=sh)
        move(std::max(0,std::min(x0,sw - x1 + x0)),
             std::max(0,std::min(y0,sh - y1 + y0)));
      return *this;
    }

    //@}
    //---------------------------------------
    //
    //! \name Window Manipulation
    //@{
    //---------------------------------------

#if cimg_display==0

    //! Display image on associated window.
    /**
       \param img Input image to display.
       \note This function returns immediately.
    **/
    template<typename T>
    CImgDisplay& display(const CImg<T>& img) {
      return assign(img);
    }

#endif

    //! Display list of images on associated window.
    /**
       \param list List of images to display.
       \param axis Axis along which to append the images for the visualization (can be \c x, \c y, \c z or \c c).
       \param align Relative position of aligned images when displaying lists with images of different sizes
       (\c 0 for upper-left, \c 0.5 for centering and \c 1 for lower-right).
       \note This function returns immediately.
    **/
    template<typename T>
    CImgDisplay& display(const CImgList<T>& list, const char axis='x', const float align=0) {
      if (list._width==1) {
        const CImg<T>& img = list[0];
        if (img._depth==1 && (img._spectrum==1 || img._spectrum>=3) && _normalization!=1) return display(img);
      }
      CImgList<typename CImg<T>::ucharT> visu(list._width);
      unsigned int dims = 0;
      cimglist_for(list,l) {
        const CImg<T>& img = list._data[l];
        img._get_select(*this,_normalization,(img._width - 1)/2,(img._height - 1)/2,
                        (img._depth - 1)/2).move_to(visu[l]);
        dims = std::max(dims,visu[l]._spectrum);
      }
      cimglist_for(list,l) if (visu[l]._spectrum<dims) visu[l].resize(-100,-100,-100,dims,1);
      visu.get_append(axis,align).display(*this);
      return *this;
    }

#if cimg_display==0

    //! Show (closed) associated window on the screen.
    /**
       \note
       - Force the associated window of a display to be visible on the screen, even if it has been closed before.
       - Using show() on a visible display does nothing.
    **/
    CImgDisplay& show() {
      return assign();
    }

    //! Close (visible) associated window and make it disappear from the screen.
    /**
       \note
       - A closed display only means the associated window is not visible anymore. This does not mean the display has
       been destroyed.
       Use show() to make the associated window reappear.
       - Using close() on a closed display does nothing.
    **/
    CImgDisplay& close() {
      return assign();
    }

    //! Move associated window to a new location.
    /**
       \param pos_x X-coordinate of the new window location.
       \param pos_y Y-coordinate of the new window location.
       \note Depending on the window manager behavior, this function may not succeed (no exceptions are thrown
       nevertheless).
    **/
    CImgDisplay& move(const int pos_x, const int pos_y) {
      return assign(pos_x,pos_y);
    }

#endif

    //! Resize display to the size of the associated window.
    /**
       \param force_redraw Indicates whether the previous window content must be updated and refreshed as well.
       \note
       - Calling this function ensures that width() and window_width() become equal, as well as height() and
       window_height().
       - The associated window is also resized to specified dimensions.
    **/
    CImgDisplay& resize(const bool force_redraw=true) {
      resize(window_width(),window_height(),force_redraw);
      return *this;
    }

#if cimg_display==0

    //! Resize display to the specified size.
    /**
       \param width Requested display width.
       \param height Requested display height.
       \param force_redraw Indicates whether the previous window content must be updated and refreshed as well.
       \note The associated window is also resized to specified dimensions.
    **/
    CImgDisplay& resize(const int width, const int height, const bool force_redraw=true) {
      return assign(width,height,0,3,force_redraw);
    }

#endif

    //! Resize display to the size of an input image.
    /**
       \param img Input image to take size from.
       \param force_redraw Indicates whether the previous window content must be resized and updated as well.
       \note
       - Calling this function ensures that width() and <tt>img.width()</tt> become equal, as well as height() and
       <tt>img.height()</tt>.
       - The associated window is also resized to specified dimensions.
    **/
    template<typename T>
    CImgDisplay& resize(const CImg<T>& img, const bool force_redraw=true) {
      return resize(img._width,img._height,force_redraw);
    }

    //! Resize display to the size of another CImgDisplay instance.
    /**
       \param disp Input display to take size from.
       \param force_redraw Indicates whether the previous window content must be resized and updated as well.
       \note
       - Calling this function ensures that width() and <tt>disp.width()</tt> become equal, as well as height() and
       <tt>disp.height()</tt>.
       - The associated window is also resized to specified dimensions.
    **/
    CImgDisplay& resize(const CImgDisplay& disp, const bool force_redraw=true) {
      return resize(disp.width(),disp.height(),force_redraw);
    }

    // [internal] Render a pixel buffer of size (wd,hd) from a source buffer of size (ws,hs).
    template<typename t, typename T>
    static void _render_resize(const T *ptrs, const unsigned int ws, const unsigned int hs,
                               t *ptrd, const unsigned int wd, const unsigned int hd) {
      typedef typename cimg::last<T,cimg_uint64>::type uint64T;
      const uint64T one = (uint64T)1;
      CImg<uint64T> off_x(wd), off_y(hd + 1);
      if (wd==ws) off_x.fill(1);
      else {
        uint64T *poff_x = off_x._data, curr = 0;
        for (unsigned int x = 0; x<wd; ++x) {
          const uint64T old = curr;
          curr = (x + one)*ws/wd;
          *(poff_x++) = curr - old;
        }
      }
      if (hd==hs) off_y.fill(ws);
      else {
        uint64T *poff_y = off_y._data, curr = 0;
        for (unsigned int y = 0; y<hd; ++y) {
          const uint64T old = curr;
          curr = (y + one)*hs/hd;
          *(poff_y++) = ws*(curr - old);
        }
        *poff_y = 0;
      }
      uint64T *poff_y = off_y._data;
      for (unsigned int y = 0; y<hd; ) {
        const T *ptr = ptrs;
        uint64T *poff_x = off_x._data;
        for (unsigned int x = 0; x<wd; ++x) { *(ptrd++) = *ptr; ptr+=*(poff_x++); }
        ++y;
        uint64T dy = *(poff_y++);
        for ( ; !dy && y<hd; std::memcpy(ptrd,ptrd - wd,sizeof(t)*wd), ++y, ptrd+=wd, dy = *(poff_y++)) {}
        ptrs+=dy;
      }
    }

    //! Set normalization type.
    /**
       \param normalization New normalization mode.
    **/
    CImgDisplay& set_normalization(const unsigned int normalization) {
      _normalization = normalization;
      _min = _max = 0;
      return *this;
    }

#if cimg_display==0

    //! Set title of the associated window.
    /**
       \param format C-string containing the format of the title, as with <tt>std::printf()</tt>.
       \warning As the first argument is a format string, it is highly recommended to write
       \code
       disp.set_title("%s",window_title);
       \endcode
       instead of
       \code
       disp.set_title(window_title);
       \endcode
       if \c window_title can be arbitrary, to prevent memory access violations (or undefined behavior).
    **/
    CImgDisplay& set_title(const char *const format, ...) {
      return assign(0,0,format);
    }

#endif

    //! Enable or disable fullscreen mode.
    /**
       \param is_fullscreen Indicates whether fullscreen mode must be activated.
       \param force_redraw Indicates whether the previous window content must be displayed as well.
       \note
       - When fullscreen mode is enabled, the associated window fills the entire screen but the size of the
       current display is not modified.
       - The screen resolution may be switched to fit the associated window size and ensure it appears as large
       as possible.
       For X-Window (X11) users, the configuration flag \c cimg_use_xrandr has to be set to allow the screen
       resolution change (requires the X11 extensions to be enabled).
    **/
    CImgDisplay& set_fullscreen(const bool is_fullscreen, const bool force_redraw=true) {
      if (is_empty() || _is_fullscreen==is_fullscreen) return *this;
      return toggle_fullscreen(force_redraw);
    }

#if cimg_display==0

    //! Toggle fullscreen mode.
    /**
       \param force_redraw Indicates whether the previous window content must be displayed as well.
       \note Enable fullscreen mode if it was not enabled, and disable it otherwise.
    **/
    CImgDisplay& toggle_fullscreen(const bool force_redraw=true) {
      return assign(_width,_height,0,3,force_redraw);
    }

    //! Show mouse pointer.
    /**
       \note Depending on the window manager behavior, this function may not succeed
       (no exceptions are thrown nevertheless).
    **/
    CImgDisplay& show_mouse() {
      return assign();
    }

    //! Hide mouse pointer.
    /**
       \note Depending on the window manager behavior, this function may not succeed
       (no exceptions are thrown nevertheless).
    **/
    CImgDisplay& hide_mouse() {
      return assign();
    }

    //! Move mouse pointer to a specified location.
    /**
       \note Depending on the window manager behavior, this function may not succeed
       (no exceptions are thrown nevertheless).
    **/
    CImgDisplay& set_mouse(const int pos_x, const int pos_y) {
      return assign(pos_x,pos_y);
    }

#endif

    //! Simulate a mouse button release event.
    /**
       \note All mouse buttons are considered released at the same time.
    **/
    CImgDisplay& set_button() {
      _button = 0;
      _is_event = true;
#if cimg_display==1
      pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
      SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      return *this;
    }

    //! Simulate a mouse button press or release event.
    /**
       \param button Buttons event code, where each button is associated with a single bit.
       \param is_pressed Indicates whether the mouse button is considered as pressed or released.
    **/
    CImgDisplay& set_button(const unsigned int button, const bool is_pressed=true) {
      const unsigned int buttoncode = button==1U?1U:button==2U?2U:button==3U?4U:0U;
      if (is_pressed) _button|=buttoncode; else _button&=~buttoncode;
      _is_event = buttoncode?true:false;
      if (buttoncode) {
#if cimg_display==1
        pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
        SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      }
      return *this;
    }

    //! Flush all mouse wheel events.
    /**
       \note Make wheel() to return \c 0, if called afterwards.
    **/
    CImgDisplay& set_wheel() {
      _wheel = 0;
      _is_event = true;
#if cimg_display==1
      pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
      SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      return *this;
    }

    //! Simulate a wheel event.
    /**
       \param amplitude Amplitude of the wheel scrolling to simulate.
       \note Make wheel() to return \c amplitude, if called afterwards.
    **/
    CImgDisplay& set_wheel(const int amplitude) {
      _wheel+=amplitude;
      _is_event = amplitude?true:false;
      if (amplitude) {
#if cimg_display==1
        pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
        SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      }
      return *this;
    }

    //! Flush all key events.
    /**
       \note Make key() to return \c 0, if called afterwards.
    **/
    CImgDisplay& set_key() {
      std::memset((void*)_keys,0,128*sizeof(unsigned int));
      std::memset((void*)_released_keys,0,128*sizeof(unsigned int));
      _is_keyESC = _is_keyF1 = _is_keyF2 = _is_keyF3 = _is_keyF4 = _is_keyF5 = _is_keyF6 = _is_keyF7 = _is_keyF8 =
        _is_keyF9 = _is_keyF10 = _is_keyF11 = _is_keyF12 = _is_keyPAUSE = _is_key1 = _is_key2 = _is_key3 = _is_key4 =
        _is_key5 = _is_key6 = _is_key7 = _is_key8 = _is_key9 = _is_key0 = _is_keyBACKSPACE = _is_keyINSERT =
        _is_keyHOME = _is_keyPAGEUP = _is_keyTAB = _is_keyQ = _is_keyW = _is_keyE = _is_keyR = _is_keyT = _is_keyY =
        _is_keyU = _is_keyI = _is_keyO = _is_keyP = _is_keyDELETE = _is_keyEND = _is_keyPAGEDOWN = _is_keyCAPSLOCK =
        _is_keyA = _is_keyS = _is_keyD = _is_keyF = _is_keyG = _is_keyH = _is_keyJ = _is_keyK = _is_keyL =
        _is_keyRETURN = _is_keySHIFTLEFT = _is_keyZ = _is_keyX = _is_keyC = _is_keyV = _is_keyB = _is_keyN =
        _is_keyM = _is_keySHIFTRIGHT = _is_keyARROWUP = _is_keyCTRLLEFT = _is_keyAPPLEFT = _is_keyALT = _is_keySPACE =
        _is_keyALTGR = _is_keyAPPRIGHT = _is_keyMENU = _is_keyCTRLRIGHT = _is_keyARROWLEFT = _is_keyARROWDOWN =
        _is_keyARROWRIGHT = _is_keyPAD0 = _is_keyPAD1 = _is_keyPAD2 = _is_keyPAD3 = _is_keyPAD4 = _is_keyPAD5 =
        _is_keyPAD6 = _is_keyPAD7 = _is_keyPAD8 = _is_keyPAD9 = _is_keyPADADD = _is_keyPADSUB = _is_keyPADMUL =
        _is_keyPADDIV = _is_keyENTER = false;
      _is_event = true;
#if cimg_display==1
      pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
      SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      return *this;
    }

    //! Simulate a keyboard press/release event.
    /**
       \param keycode Keycode of the associated key.
       \param is_pressed Indicates whether the key is considered as pressed or released.
       \note Keycode constants are defined in the cimg namespace and are architecture-dependent. Use them to ensure
       your code stay portable (see cimg::keyESC).
    **/
    CImgDisplay& set_key(const unsigned int keycode, const bool is_pressed=true) {
#define _cimg_set_key(k) if (keycode==cimg::key##k) _is_key##k = is_pressed;
      _cimg_set_key(ESC); _cimg_set_key(F1); _cimg_set_key(F2); _cimg_set_key(F3);
      _cimg_set_key(F4); _cimg_set_key(F5); _cimg_set_key(F6); _cimg_set_key(F7);
      _cimg_set_key(F8); _cimg_set_key(F9); _cimg_set_key(F10); _cimg_set_key(F11);
      _cimg_set_key(F12); _cimg_set_key(PAUSE); _cimg_set_key(1); _cimg_set_key(2);
      _cimg_set_key(3); _cimg_set_key(4); _cimg_set_key(5); _cimg_set_key(6);
      _cimg_set_key(7); _cimg_set_key(8); _cimg_set_key(9); _cimg_set_key(0);
      _cimg_set_key(BACKSPACE); _cimg_set_key(INSERT); _cimg_set_key(HOME);
      _cimg_set_key(PAGEUP); _cimg_set_key(TAB); _cimg_set_key(Q); _cimg_set_key(W);
      _cimg_set_key(E); _cimg_set_key(R); _cimg_set_key(T); _cimg_set_key(Y);
      _cimg_set_key(U); _cimg_set_key(I); _cimg_set_key(O); _cimg_set_key(P);
      _cimg_set_key(DELETE); _cimg_set_key(END); _cimg_set_key(PAGEDOWN);
      _cimg_set_key(CAPSLOCK); _cimg_set_key(A); _cimg_set_key(S); _cimg_set_key(D);
      _cimg_set_key(F); _cimg_set_key(G); _cimg_set_key(H); _cimg_set_key(J);
      _cimg_set_key(K); _cimg_set_key(L); _cimg_set_key(RETURN);
      _cimg_set_key(SHIFTLEFT); _cimg_set_key(Z); _cimg_set_key(X); _cimg_set_key(C);
      _cimg_set_key(V); _cimg_set_key(B); _cimg_set_key(N); _cimg_set_key(M);
      _cimg_set_key(SHIFTRIGHT); _cimg_set_key(ARROWUP); _cimg_set_key(CTRLLEFT);
      _cimg_set_key(APPLEFT); _cimg_set_key(ALT); _cimg_set_key(SPACE); _cimg_set_key(ALTGR);
      _cimg_set_key(APPRIGHT); _cimg_set_key(MENU); _cimg_set_key(CTRLRIGHT);
      _cimg_set_key(ARROWLEFT); _cimg_set_key(ARROWDOWN); _cimg_set_key(ARROWRIGHT);
      _cimg_set_key(PAD0); _cimg_set_key(PAD1); _cimg_set_key(PAD2);
      _cimg_set_key(PAD3); _cimg_set_key(PAD4); _cimg_set_key(PAD5);
      _cimg_set_key(PAD6); _cimg_set_key(PAD7); _cimg_set_key(PAD8);
      _cimg_set_key(PAD9); _cimg_set_key(PADADD); _cimg_set_key(PADSUB);
      _cimg_set_key(PADMUL); _cimg_set_key(PADDIV); _cimg_set_key(ENTER);
      if (is_pressed) {
        if (*_keys)
          std::memmove((void*)(_keys + 1),(void*)_keys,127*sizeof(unsigned int));
        *_keys = keycode;
        if (*_released_keys) {
          std::memmove((void*)(_released_keys + 1),(void*)_released_keys,127*sizeof(unsigned int));
          *_released_keys = 0;
        }
      } else {
        if (*_keys) {
          std::memmove((void*)(_keys + 1),(void*)_keys,127*sizeof(unsigned int));
          *_keys = 0;
        }
        if (*_released_keys)
          std::memmove((void*)(_released_keys + 1),(void*)_released_keys,127*sizeof(unsigned int));
        *_released_keys = keycode;
      }
      _is_event = keycode?true:false;
      if (keycode) {
#if cimg_display==1
        pthread_cond_broadcast(&cimg::X11_attr::ref().wait_event);
#elif cimg_display==2
        SetEvent(cimg::Win32_attr::ref().wait_event);
#endif
      }
      return *this;
    }

    //! Flush all display events.
    /**
       \note Remove all passed events from the current display.
    **/
    CImgDisplay& flush() {
      set_key().set_button().set_wheel();
      _is_resized = _is_moved = _is_event = false;
      _fps_timer = _fps_frames = _timer = 0;
      _fps_fps = 0;
      return *this;
    }

    //! Wait for any user event occurring on the current display.
    CImgDisplay& wait() {
      wait(*this);
      return *this;
    }

    //! Wait for any event occurring on the display \c disp1.
    static void wait(CImgDisplay& disp1) {
      disp1._is_event = false;
      while (!disp1._is_closed && !disp1._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1 or \c disp2.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2) {
      disp1._is_event = disp2._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed) &&
             !disp1._is_event && !disp2._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2 or \c disp3.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3) {
      disp1._is_event = disp2._is_event = disp3._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3 or \c disp4.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4 or \c disp5.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4,
                     CImgDisplay& disp5) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event)
        wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4, ... \c disp6.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4, CImgDisplay& disp5,
                     CImgDisplay& disp6) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event =
        disp6._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed ||
              !disp6._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event &&
             !disp6._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4, ... \c disp7.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4, CImgDisplay& disp5,
                     CImgDisplay& disp6, CImgDisplay& disp7) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event =
        disp6._is_event = disp7._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed ||
              !disp6._is_closed || !disp7._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event &&
             !disp6._is_event && !disp7._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4, ... \c disp8.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4, CImgDisplay& disp5,
                     CImgDisplay& disp6, CImgDisplay& disp7, CImgDisplay& disp8) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event =
        disp6._is_event = disp7._is_event = disp8._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed ||
              !disp6._is_closed || !disp7._is_closed || !disp8._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event &&
             !disp6._is_event && !disp7._is_event && !disp8._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4, ... \c disp9.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4, CImgDisplay& disp5,
                     CImgDisplay& disp6, CImgDisplay& disp7, CImgDisplay& disp8, CImgDisplay& disp9) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event =
        disp6._is_event = disp7._is_event = disp8._is_event = disp9._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed ||
              !disp6._is_closed || !disp7._is_closed || !disp8._is_closed || !disp9._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event &&
             !disp6._is_event && !disp7._is_event && !disp8._is_event && !disp9._is_event) wait_all();
    }

    //! Wait for any event occurring either on the display \c disp1, \c disp2, \c disp3, \c disp4, ... \c disp10.
    static void wait(CImgDisplay& disp1, CImgDisplay& disp2, CImgDisplay& disp3, CImgDisplay& disp4, CImgDisplay& disp5,
                     CImgDisplay& disp6, CImgDisplay& disp7, CImgDisplay& disp8, CImgDisplay& disp9,
                     CImgDisplay& disp10) {
      disp1._is_event = disp2._is_event = disp3._is_event = disp4._is_event = disp5._is_event =
        disp6._is_event = disp7._is_event = disp8._is_event = disp9._is_event = disp10._is_event = false;
      while ((!disp1._is_closed || !disp2._is_closed || !disp3._is_closed || !disp4._is_closed || !disp5._is_closed ||
              !disp6._is_closed || !disp7._is_closed || !disp8._is_closed || !disp9._is_closed || !disp10._is_closed) &&
             !disp1._is_event && !disp2._is_event && !disp3._is_event && !disp4._is_event && !disp5._is_event &&
             !disp6._is_event && !disp7._is_event && !disp8._is_event && !disp9._is_event && !disp10._is_event)
        wait_all();
    }

#if cimg_display==0

    //! Wait for any window event occurring in any opened CImgDisplay.
    static void wait_all() {
      return _no_display_exception();
    }

    //! Wait for a given number of milliseconds since the last call to wait().
    /**
       \param milliseconds Number of milliseconds to wait for.
       \note Similar to cimg::wait().
    **/
    CImgDisplay& wait(const unsigned int milliseconds) {
      cimg::wait(milliseconds,&_timer);
      return *this;
    }

    //! Render image into internal display buffer.
    /**
       \param img Input image data to render.
       \note
       - Convert image data representation into the internal display buffer (architecture-dependent structure).
       - The content of the associated window is not modified, until paint() is called.
       - Should not be used for common CImgDisplay uses, since display() is more useful.
    **/
    template<typename T>
    CImgDisplay& render(const CImg<T>& img) {
      return assign(img);
    }

    //! Paint internal display buffer on associated window.
    /**
       \note
       - Update the content of the associated window with the internal display buffer, e.g. after a render() call.
       - Should not be used for common CImgDisplay uses, since display() is more useful.
    **/
    CImgDisplay& paint() {
      return assign();
    }

    //! Take a snapshot of the current screen content.
    /**
       \param x0 X-coordinate of the upper left corner.
       \param y0 Y-coordinate of the upper left corner.
       \param x1 X-coordinate of the lower right corner.
       \param y1 Y-coordinate of the lower right corner.
       \param[out] img Output screenshot. Can be empty on input
    **/
    template<typename T>
    static void screenshot(const int x0, const int y0, const int x1, const int y1, CImg<T>& img) {
      cimg::unused(x0,y0,x1,y1,&img);
      _no_display_exception();
    }

    //! Take a snapshot of the associated window content.
    /**
       \param[out] img Output snapshot. Can be empty on input.
    **/
    template<typename T>
    const CImgDisplay& snapshot(CImg<T>& img) const {
      cimg::unused(img);
      _no_display_exception();
      return *this;
    }
#endif

    // X11-based implementation.
    //--------------------------
#if cimg_display==1

    Atom _wm_window_atom, _wm_protocol_atom;
    Window _window, _background_window;
    Colormap _colormap;
    XImage *_image;
    void *_data;

#ifdef cimg_use_xshm
    XShmSegmentInfo *_shminfo;
#endif

    // Internal functions.
    void _assign(const unsigned int dimw, const unsigned int dimh, const char *const p_title=0,
                 const unsigned int normalization_type=3,
                 const bool is_fullscreen=false, const bool closed_flag=false) {
      cimg::mutex(14);

      // Allocate space for window title.
      const char *const np_title = p_title?p_title:"";
      const unsigned int s = (unsigned int)std::strlen(np_title) + 1;
      char *const tmp_title = s?new char[s]:0;
      if (s) std::memcpy(tmp_title,np_title,s*sizeof(char));

      // Destroy previous display window if existing.
      if (!is_empty()) assign(false);

      // Open X11 display and retrieve graphical properties.
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      if (X11_attr.nb_cimg_displays>=512) {
        X11_attr.unlock();
        throw CImgDisplayException("CImgDisplay::assign(): Max number of displays (512) already opened.");
      }

      Display* &dpy = X11_attr.display;
      if (!dpy) {
        dpy = XOpenDisplay(0);
        if (!dpy)
          throw CImgDisplayException(_cimgdisplay_instance
                                     "assign(): Failed to open X11 display.",
                                     cimgdisplay_instance);

        X11_attr.nb_bits = DefaultDepth(dpy,DefaultScreen(dpy));
        if (X11_attr.nb_bits!=8 && X11_attr.nb_bits!=16 &&
            X11_attr.nb_bits!=24 && X11_attr.nb_bits!=32)
          throw CImgDisplayException(_cimgdisplay_instance
                                     "assign(): Invalid %u bits screen mode detected "
                                     "(only 8, 16, 24 and 32 bits modes are managed).",
                                     cimgdisplay_instance,
                                     X11_attr.nb_bits);
        XVisualInfo vtemplate;
        vtemplate.visualid = XVisualIDFromVisual(DefaultVisual(dpy,DefaultScreen(dpy)));
        int nb_visuals;
        XVisualInfo *vinfo = XGetVisualInfo(dpy,VisualIDMask,&vtemplate,&nb_visuals);
        if (vinfo && vinfo->red_mask<vinfo->blue_mask) X11_attr.is_blue_first = true;
        X11_attr.byte_order = ImageByteOrder(dpy);
        XFree(vinfo);
      }

      X11_attr.lock();
      if (!X11_attr.events_thread) {
        X11_attr.events_thread = new pthread_t;
        pthread_create(X11_attr.events_thread,0,_events_thread,0);
      }

      // Set display variables.
      _width = std::min(dimw,(unsigned int)screen_width());
      _height = std::min(dimh,(unsigned int)screen_height());
      _normalization = normalization_type<4?normalization_type:3;
      _is_fullscreen = is_fullscreen;
      _window_x = _window_y = cimg::type<int>::min();
      _is_closed = closed_flag;
      _title = tmp_title;
      flush();

      // Create X11 window (and LUT, if 8bits display).
      if (_is_fullscreen) {
        if (!_is_closed) _init_fullscreen();
        const unsigned int sx = screen_width(), sy = screen_height();
        XSetWindowAttributes attr_set;
        attr_set.override_redirect = 1;
        _window = XCreateWindow(dpy,DefaultRootWindow(dpy),(sx - _width)/2,(sy - _height)/2,_width,_height,0,0,
                                InputOutput,CopyFromParent,CWOverrideRedirect,&attr_set);
      } else
        _window = XCreateSimpleWindow(dpy,DefaultRootWindow(dpy),0,0,_width,_height,0,0L,0L);

      XSelectInput(dpy,_window,
                   ExposureMask | StructureNotifyMask | ButtonPressMask | KeyPressMask | PointerMotionMask |
                   EnterWindowMask | LeaveWindowMask | ButtonReleaseMask | KeyReleaseMask);

      XStoreName(dpy,_window,_title?_title:" ");
      if (X11_attr.nb_bits==8) {
        _colormap = XCreateColormap(dpy,_window,DefaultVisual(dpy,DefaultScreen(dpy)),AllocAll);
        _set_colormap(_colormap,3);
        XSetWindowColormap(dpy,_window,_colormap);
      }

      static const char *const _window_class = cimg_appname;
      XClassHint *const window_class = XAllocClassHint();
      window_class->res_name = (char*)_window_class;
      window_class->res_class = (char*)_window_class;
      XSetClassHint(dpy,_window,window_class);
      XFree(window_class);

      _window_width = _width;
      _window_height = _height;

      // Create XImage.
#ifdef cimg_use_xshm
      _shminfo = 0;
      if (XShmQueryExtension(dpy)) {
        _shminfo = new XShmSegmentInfo;
        _image = XShmCreateImage(dpy,DefaultVisual(dpy,DefaultScreen(dpy)),X11_attr.nb_bits,
                                 ZPixmap,0,_shminfo,_width,_height);
        if (!_image) { delete _shminfo; _shminfo = 0; }
        else {
          _shminfo->shmid = shmget(IPC_PRIVATE,_image->bytes_per_line*_image->height,IPC_CREAT|0777);
          if (_shminfo->shmid==-1) { XDestroyImage(_image); delete _shminfo; _shminfo = 0; }
          else {
            _shminfo->shmaddr = _image->data = (char*)(_data = shmat(_shminfo->shmid,0,0));
            if (_shminfo->shmaddr==(char*)-1) {
              shmctl(_shminfo->shmid,IPC_RMID,0); XDestroyImage(_image); delete _shminfo; _shminfo = 0;
            } else {
              _shminfo->readOnly = 0;
              X11_attr.is_shm_enabled = true;
              XErrorHandler oldXErrorHandler = XSetErrorHandler(_assign_xshm);
              XShmAttach(dpy,_shminfo);
              XSync(dpy,0);
              XSetErrorHandler(oldXErrorHandler);
              if (!X11_attr.is_shm_enabled) {
                shmdt(_shminfo->shmaddr); shmctl(_shminfo->shmid,IPC_RMID,0); XDestroyImage(_image);
                delete _shminfo; _shminfo = 0;
              }
            }
          }
        }
      }
      if (!_shminfo)
#endif
        {
          const cimg_ulong buf_size = (cimg_ulong)_width*_height*(X11_attr.nb_bits==8?1:
                                                                  (X11_attr.nb_bits==16?2:4));
          _data = std::malloc(buf_size);
          _image = XCreateImage(dpy,DefaultVisual(dpy,DefaultScreen(dpy)),X11_attr.nb_bits,
                                ZPixmap,0,(char*)_data,_width,_height,8,0);
        }

      _wm_window_atom = XInternAtom(dpy,"WM_DELETE_WINDOW",0);
      _wm_protocol_atom = XInternAtom(dpy,"WM_PROTOCOLS",0);
      XSetWMProtocols(dpy,_window,&_wm_window_atom,1);

      if (_is_fullscreen) XGrabKeyboard(dpy,_window,1,GrabModeAsync,GrabModeAsync,CurrentTime);
      X11_attr.cimg_displays[X11_attr.nb_cimg_displays++] = this;
      if (!_is_closed) _map_window(); else _window_x = _window_y = cimg::type<int>::min();
      X11_attr.unlock();
      cimg::mutex(14,0);
    }

    static int _assign_xshm(Display *dpy, XErrorEvent *error) {
      cimg::unused(dpy,error);
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      X11_attr.is_shm_enabled = false;
      return 0;
    }

    void _desinit_fullscreen() {
      if (!_is_fullscreen) return;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      XUngrabKeyboard(dpy,CurrentTime);

#ifdef cimg_use_xrandr
      if (X11_attr.resolutions && X11_attr.curr_resolution) {
        XRRScreenConfiguration *config = XRRGetScreenInfo(dpy,DefaultRootWindow(dpy));
        XRRSetScreenConfig(dpy,config,DefaultRootWindow(dpy),0,X11_attr.curr_rotation,CurrentTime);
        XRRFreeScreenConfigInfo(config);
        XSync(dpy,0);
        X11_attr.curr_resolution = 0;
      }
#endif
      if (_background_window) XDestroyWindow(dpy,_background_window);
      _background_window = 0;
      _is_fullscreen = false;
    }

    static void* _events_thread(void*) { // Thread to manage events for all opened display windows
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      X11_attr.events_thread_running = true;

      Display *const dpy = X11_attr.display;
      XEvent event;
      while (X11_attr.events_thread_running) {
        X11_attr.lock();
        bool is_event = XCheckTypedEvent(dpy,ClientMessage,&event);
        if (!is_event) is_event = XCheckMaskEvent(dpy,
                                                  ExposureMask | StructureNotifyMask | ButtonPressMask |
                                                  KeyPressMask | PointerMotionMask | EnterWindowMask |
                                                  LeaveWindowMask | ButtonReleaseMask | KeyReleaseMask,&event);
        if (is_event) { // Find CImgDisplay associated with event
          for (unsigned int k = 0; k<X11_attr.nb_cimg_displays; ++k)
            if (event.xany.window==X11_attr.cimg_displays[k]->_window) {
              if (!X11_attr.cimg_displays[k]->_is_closed && X11_attr.events_thread_running)
                X11_attr.cimg_displays[k]->_process_event(&event);
              break;
            }
          X11_attr.unlock();
        } else {
          X11_attr.unlock();
          cimg::sleep(8);
        }
        pthread_testcancel();
      }
      return 0;
    }

    void _init_fullscreen() {
      if (!_is_fullscreen || _is_closed) return;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      _background_window = 0;

#ifdef cimg_use_xrandr
      int foo;
      if (XRRQueryExtension(dpy,&foo,&foo)) {
        XRRRotations(dpy,DefaultScreen(dpy),&X11_attr.curr_rotation);
        if (!X11_attr.resolutions) {
          X11_attr.resolutions = XRRSizes(dpy,DefaultScreen(dpy),&foo);
          X11_attr.nb_resolutions = (unsigned int)foo;
        }
        if (X11_attr.resolutions) {
          X11_attr.curr_resolution = 0;
          for (unsigned int i = 0; i<X11_attr.nb_resolutions; ++i) {
            const unsigned int
              nw = (unsigned int)(X11_attr.resolutions[i].width),
              nh = (unsigned int)(X11_attr.resolutions[i].height);
            if (nw>=_width && nh>=_height &&
                nw<=(unsigned int)(X11_attr.resolutions[X11_attr.curr_resolution].width) &&
                nh<=(unsigned int)(X11_attr.resolutions[X11_attr.curr_resolution].height))
              X11_attr.curr_resolution = i;
          }
          if (X11_attr.curr_resolution>0) {
            XRRScreenConfiguration *config = XRRGetScreenInfo(dpy,DefaultRootWindow(dpy));
            XRRSetScreenConfig(dpy,config,DefaultRootWindow(dpy),
                               X11_attr.curr_resolution,X11_attr.curr_rotation,CurrentTime);
            XRRFreeScreenConfigInfo(config);
            XSync(dpy,0);
          }
        }
      }
      if (!X11_attr.resolutions)
        cimg::warn(_cimgdisplay_instance
                   "init_fullscreen(): Xrandr extension not supported by the X server.",
                   cimgdisplay_instance);
#endif

      const unsigned int sx = screen_width(), sy = screen_height();
      if (sx==_width && sy==_height) return;
      XSetWindowAttributes attr_set;

      attr_set.background_pixel = XBlackPixel(dpy,XDefaultScreen(dpy));
      attr_set.override_redirect = 1;
      _background_window = XCreateWindow(dpy,DefaultRootWindow(dpy),0,0,sx,sy,0,0,
                                         InputOutput,CopyFromParent,CWBackPixel | CWOverrideRedirect,&attr_set);
      XEvent event;
      XSelectInput(dpy,_background_window,StructureNotifyMask);
      XMapRaised(dpy,_background_window);
      do XWindowEvent(dpy,_background_window,StructureNotifyMask,&event);
      while (event.type!=MapNotify);

      XWindowAttributes attr;
      do {
        XGetWindowAttributes(dpy,_background_window,&attr);
        if (attr.map_state!=IsViewable) { XSync(dpy,0); cimg::sleep(10); }
      } while (attr.map_state!=IsViewable);
    }

    void _map_window() {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      bool is_exposed = false, is_mapped = false;
      XWindowAttributes attr;
      XEvent event;
      XMapRaised(dpy,_window);
      do { // Wait for the window to be mapped
        XWindowEvent(dpy,_window,StructureNotifyMask | ExposureMask,&event);
        switch (event.type) {
        case MapNotify : is_mapped = true; break;
        case Expose : is_exposed = true; break;
        }
      } while (!is_exposed || !is_mapped);
      do { // Wait for the window to be visible
        XGetWindowAttributes(dpy,_window,&attr);
        if (attr.map_state!=IsViewable) { XSync(dpy,0); cimg::sleep(10); }
      } while (attr.map_state!=IsViewable);
      _window_x = attr.x;
      _window_y = attr.y;
    }

    void _paint(const bool wait_expose=true) {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      if (_is_closed || !_image) return;
      Display *const dpy = X11_attr.display;
      if (wait_expose) { // Send an expose event sticked to display window to force repaint
        XEvent event = {};
        event.xexpose.type = Expose;
        event.xexpose.serial = 0;
        event.xexpose.send_event = 1;
        event.xexpose.display = dpy;
        event.xexpose.window = _window;
        event.xexpose.x = 0;
        event.xexpose.y = 0;
        event.xexpose.width = width();
        event.xexpose.height = height();
        event.xexpose.count = 0;
        XSendEvent(dpy,_window,0,0,&event);
      } else { // Repaint directly (may be called from the expose event)
        GC gc = DefaultGC(dpy,DefaultScreen(dpy));

#ifdef cimg_use_xshm
        if (_shminfo) XShmPutImage(dpy,_window,gc,_image,0,0,0,0,_width,_height,1);
        else XPutImage(dpy,_window,gc,_image,0,0,0,0,_width,_height);
#else
        XPutImage(dpy,_window,gc,_image,0,0,0,0,_width,_height);
#endif
      }
    }

    void _process_event(XEvent *const p_event) {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      XEvent &event = *p_event;
      bool is_event = false;

      switch (event.type) {
      case ClientMessage : {
        if ((int)event.xclient.message_type==(int)_wm_protocol_atom &&
            (int)event.xclient.data.l[0]==(int)_wm_window_atom) {
          XUnmapWindow(X11_attr.display,_window);
          _is_closed = is_event = true;
        }
      } break;
      case ConfigureNotify : {
        while (XCheckWindowEvent(dpy,_window,StructureNotifyMask,&event)) {}
        const unsigned int nw = event.xconfigure.width, nh = event.xconfigure.height;
        const int nx = event.xconfigure.x, ny = event.xconfigure.y;
        if (nw && nh && (nw!=_window_width || nh!=_window_height)) {
          _window_width = nw; _window_height = nh; _mouse_x = _mouse_y = -1;
          XResizeWindow(dpy,_window,_window_width,_window_height);
          _is_resized = is_event = true;
        }
        if (nx!=_window_x || ny!=_window_y) {
          _window_x = nx;
          _window_y = ny;
          _is_moved = is_event = true;
        }
      } break;
      case Expose : {
        while (XCheckWindowEvent(dpy,_window,ExposureMask,&event)) {}
        _paint(false);
        if (_is_fullscreen) {
          XWindowAttributes attr;
          do {
            XGetWindowAttributes(dpy,_window,&attr);
            if (attr.map_state!=IsViewable) { XSync(dpy,0); cimg::sleep(10); }
          } while (attr.map_state!=IsViewable);
          XSetInputFocus(dpy,_window,RevertToParent,CurrentTime);
        }
      } break;
      case ButtonPress : {
        do {
          _mouse_x = event.xmotion.x; _mouse_y = event.xmotion.y;
          if (_mouse_x<0 || _mouse_y<0 || _mouse_x>=width() || _mouse_y>=height()) _mouse_x = _mouse_y = -1;
          switch (event.xbutton.button) {
          case 1 : set_button(1); break;
          case 3 : set_button(2); break;
          case 2 : set_button(3); break;
          }
        } while (XCheckWindowEvent(dpy,_window,ButtonPressMask,&event));
      } break;
      case ButtonRelease : {
        do {
          _mouse_x = event.xmotion.x; _mouse_y = event.xmotion.y;
          if (_mouse_x<0 || _mouse_y<0 || _mouse_x>=width() || _mouse_y>=height()) _mouse_x = _mouse_y = -1;
          switch (event.xbutton.button) {
          case 1 : set_button(1,false); break;
          case 3 : set_button(2,false); break;
          case 2 : set_button(3,false); break;
          case 4 : set_wheel(1); break;
          case 5 : set_wheel(-1); break;
          }
        } while (XCheckWindowEvent(dpy,_window,ButtonReleaseMask,&event));
      } break;
      case KeyPress : {
        char tmp = 0; KeySym ksym;
        XLookupString(&event.xkey,&tmp,1,&ksym,0);
        set_key((unsigned int)ksym,true);
      } break;
      case KeyRelease : {
        char keys_return[32]; // Check that the key has been physically unpressed
        XQueryKeymap(dpy,keys_return);
        const unsigned int kc = event.xkey.keycode, kc1 = kc/8, kc2 = kc%8;
        const bool is_key_pressed = kc1>=32?false:(keys_return[kc1]>>kc2)&1;
        if (!is_key_pressed) {
          char tmp = 0; KeySym ksym;
          XLookupString(&event.xkey,&tmp,1,&ksym,0);
          set_key((unsigned int)ksym,false);
        }
      } break;
      case EnterNotify: {
        while (XCheckWindowEvent(dpy,_window,EnterWindowMask,&event)) {}
        _mouse_x = event.xmotion.x;
        _mouse_y = event.xmotion.y;
        if (_mouse_x<0 || _mouse_y<0 || _mouse_x>=width() || _mouse_y>=height()) _mouse_x = _mouse_y = -1;
      } break;
      case LeaveNotify : {
        while (XCheckWindowEvent(dpy,_window,LeaveWindowMask,&event)) {}
        _mouse_x = _mouse_y = -1; is_event = true;
      } break;
      case MotionNotify : {
        while (XCheckWindowEvent(dpy,_window,PointerMotionMask,&event)) {}
        _mouse_x = event.xmotion.x;
        _mouse_y = event.xmotion.y;
        if (_mouse_x<0 || _mouse_y<0 || _mouse_x>=width() || _mouse_y>=height()) _mouse_x = _mouse_y = -1;
        is_event = true;
      } break;
      }
      if (is_event) {
        _is_event = true;
        pthread_cond_broadcast(&X11_attr.wait_event);
      }
    }

    template<typename T>
    void _resize(T pixel_type, const unsigned int ndimx, const unsigned int ndimy, const bool force_redraw) {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      cimg::unused(pixel_type);

#ifdef cimg_use_xshm
      if (_shminfo) {
        XShmSegmentInfo *const nshminfo = new XShmSegmentInfo;
        XImage *const nimage = XShmCreateImage(dpy,DefaultVisual(dpy,DefaultScreen(dpy)),
                                               X11_attr.nb_bits,ZPixmap,0,nshminfo,ndimx,ndimy);
        if (!nimage) { delete nshminfo; return; }
        else {
          nshminfo->shmid = shmget(IPC_PRIVATE,ndimx*ndimy*sizeof(T),IPC_CREAT | 0777);
          if (nshminfo->shmid==-1) { XDestroyImage(nimage); delete nshminfo; return; }
          else {
            nshminfo->shmaddr = nimage->data = (char*)shmat(nshminfo->shmid,0,0);
            if (nshminfo->shmaddr==(char*)-1) {
              shmctl(nshminfo->shmid,IPC_RMID,0); XDestroyImage(nimage); delete nshminfo; return;
            } else {
              nshminfo->readOnly = 0;
              X11_attr.is_shm_enabled = true;
              XErrorHandler oldXErrorHandler = XSetErrorHandler(_assign_xshm);
              XShmAttach(dpy,nshminfo);
              XFlush(dpy);
              XSetErrorHandler(oldXErrorHandler);
              if (!X11_attr.is_shm_enabled) {
                shmdt(nshminfo->shmaddr);
                shmctl(nshminfo->shmid,IPC_RMID,0);
                XDestroyImage(nimage);
                delete nshminfo;
                return;
              } else {
                T *const ndata = (T*)nimage->data;
                if (force_redraw) _render_resize((T*)_data,_width,_height,ndata,ndimx,ndimy);
                else std::memset(ndata,0,sizeof(T)*ndimx*ndimy);
                XShmDetach(dpy,_shminfo);
                XDestroyImage(_image);
                shmdt(_shminfo->shmaddr);
                shmctl(_shminfo->shmid,IPC_RMID,0);
                delete _shminfo;
                _shminfo = nshminfo;
                _image = nimage;
                _data = (void*)ndata;
              }
            }
          }
        }
      } else
#endif
        {
          T *ndata = (T*)std::malloc(ndimx*ndimy*sizeof(T));
          if (force_redraw) _render_resize((T*)_data,_width,_height,ndata,ndimx,ndimy);
          else std::memset(ndata,0,sizeof(T)*ndimx*ndimy);
          _data = (void*)ndata;
          XDestroyImage(_image);
          _image = XCreateImage(dpy,DefaultVisual(dpy,DefaultScreen(dpy)),
                                X11_attr.nb_bits,ZPixmap,0,(char*)_data,ndimx,ndimy,8,0);
        }
    }

    void _set_colormap(Colormap& cmap, const unsigned int dim) {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      XColor *const colormap = new XColor[256];
      switch (dim) {
      case 1 : { // colormap for greyscale images
        for (unsigned int index = 0; index<256; ++index) {
          colormap[index].pixel = index;
          colormap[index].red = colormap[index].green = colormap[index].blue = (unsigned short)(index<<8);
          colormap[index].flags = DoRed | DoGreen | DoBlue;
        }
      } break;
      case 2 : { // colormap for RG images
        for (unsigned int index = 0, r = 8; r<256; r+=16)
          for (unsigned int g = 8; g<256; g+=16) {
            colormap[index].pixel = index;
            colormap[index].red = colormap[index].blue = (unsigned short)(r<<8);
            colormap[index].green = (unsigned short)(g<<8);
            colormap[index++].flags = DoRed | DoGreen | DoBlue;
          }
      } break;
      default : { // colormap for RGB images
        for (unsigned int index = 0, r = 16; r<256; r+=32)
          for (unsigned int g = 16; g<256; g+=32)
            for (unsigned int b = 32; b<256; b+=64) {
              colormap[index].pixel = index;
              colormap[index].red = (unsigned short)(r<<8);
              colormap[index].green = (unsigned short)(g<<8);
              colormap[index].blue = (unsigned short)(b<<8);
              colormap[index++].flags = DoRed | DoGreen | DoBlue;
            }
      }
      }
      XStoreColors(X11_attr.display,cmap,colormap,256);
      delete[] colormap;
    }

    // Public functions.
    static int screen_width() {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      int res = 0;
      if (!dpy) {
        Display *const _dpy = XOpenDisplay(0);
        if (!_dpy)
          throw CImgDisplayException("CImgDisplay::screen_width(): Failed to open X11 display.");
        res = DisplayWidth(_dpy,DefaultScreen(_dpy));
        XCloseDisplay(_dpy);
      } else {

#ifdef cimg_use_xrandr
        if (X11_attr.resolutions && X11_attr.curr_resolution)
          res = X11_attr.resolutions[X11_attr.curr_resolution].width;
        else res = DisplayWidth(dpy,DefaultScreen(dpy));
#else
        res = DisplayWidth(dpy,DefaultScreen(dpy));
#endif
      }
      return res;
    }

    static int screen_height() {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      int res = 0;
      if (!dpy) {
        Display *const _dpy = XOpenDisplay(0);
        if (!_dpy)
          throw CImgDisplayException("CImgDisplay::screen_height(): Failed to open X11 display.");
        res = DisplayHeight(_dpy,DefaultScreen(_dpy));
        XCloseDisplay(_dpy);
      } else {

#ifdef cimg_use_xrandr
        if (X11_attr.resolutions && X11_attr.curr_resolution)
          res = X11_attr.resolutions[X11_attr.curr_resolution].height;
        else res = DisplayHeight(dpy,DefaultScreen(dpy));
#else
        res = DisplayHeight(dpy,DefaultScreen(dpy));
#endif
      }
      return res;
    }

    static void wait_all() {
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      if (!X11_attr.display) return;
      pthread_mutex_lock(&X11_attr.mutex_wait_event);
      pthread_cond_wait(&X11_attr.wait_event,&X11_attr.mutex_wait_event);
      pthread_mutex_unlock(&X11_attr.mutex_wait_event);
    }

    CImgDisplay& wait(const unsigned int milliseconds) {
      cimg::wait(milliseconds,&_timer);
      return *this;
    }

    CImgDisplay& assign(const bool allow_terminate_events_thread=true) {
      if (is_empty()) return flush();
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      if (!dpy) return *this;
      X11_attr.lock();

      // Remove display window from event thread list.
      unsigned int i;
      for (i = 0; i<X11_attr.nb_cimg_displays && X11_attr.cimg_displays[i]!=this; ++i) {}
      for ( ; i<X11_attr.nb_cimg_displays - 1; ++i)
        X11_attr.cimg_displays[i] = X11_attr.cimg_displays[i + 1];
      --X11_attr.nb_cimg_displays;
      if (!X11_attr.nb_cimg_displays && allow_terminate_events_thread)
        X11_attr.unlock().terminate_events_thread().lock();

      // Destroy associated resources.
      if (_is_fullscreen && !_is_closed) _desinit_fullscreen();

#ifdef cimg_use_xshm
      if (_shminfo) {
        XShmDetach(dpy,_shminfo);
        shmdt(_shminfo->shmaddr);
        shmctl(_shminfo->shmid,IPC_RMID,0);
        delete _shminfo;
        _shminfo = 0;
      }
#endif

      XDestroyImage(_image);
      if (X11_attr.nb_bits==8) XFreeColormap(dpy,_colormap);
      XDestroyWindow(dpy,_window);
      XSync(dpy,0);
      _window = 0; _colormap = 0; _data = 0; _image = 0;

      // Reset display variables.
      delete[] _title;
      _width = _height = _normalization = _window_width = _window_height = 0;
      _window_x = _window_y = cimg::type<int>::min();
      _is_fullscreen = false;
      _is_closed = true;
      _min = _max = 0;
      _title = 0;
      flush();

      X11_attr.unlock();
      return *this;
    }

    CImgDisplay& assign(const unsigned int dimw, const unsigned int dimh, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!dimw || !dimh) return assign();
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      _assign(dimw,dimh,title,normalization_type,is_fullscreen,closed_flag);
      _min = _max = 0;
      std::memset(_data,0,(X11_attr.nb_bits==8?sizeof(unsigned char):
                           (X11_attr.nb_bits==16?sizeof(unsigned short):sizeof(unsigned int)))*
                  (size_t)_width*_height);
      return paint();
    }

    template<typename T>
    CImgDisplay& assign(const CImg<T>& img, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!img) return assign();
      CImg<T> tmp;
      const CImg<T>& nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                           (img._height - 1)/2,
                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return render(nimg).paint();
    }

    template<typename T>
    CImgDisplay& assign(const CImgList<T>& list, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!list) return assign();
      CImg<T> tmp;
      const CImg<T> img = list>'x', &nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                                           (img._height - 1)/2,
                                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return render(nimg).paint();
    }

    CImgDisplay& assign(const CImgDisplay& disp) {
      if (this==&disp) return *this;
      if (!disp) return assign();
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      _assign(disp._width,disp._height,disp._title,disp._normalization,disp._is_fullscreen,disp._is_closed);
      std::memcpy(_data,disp._data,(X11_attr.nb_bits==8?sizeof(unsigned char):
                                    X11_attr.nb_bits==16?sizeof(unsigned short):
                                    sizeof(unsigned int))*(size_t)_width*_height);
      return paint();
    }

    CImgDisplay& resize(const int nwidth, const int nheight, const bool force_redraw=true) {
      if (!nwidth || !nheight || (is_empty() && (nwidth<0 || nheight<0))) return assign();
      if (is_empty()) return assign(nwidth,nheight);
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      const unsigned int
        tmpdimx = (nwidth>0)?nwidth:(-nwidth*width()/100),
        tmpdimy = (nheight>0)?nheight:(-nheight*height()/100),
        dimx = tmpdimx?tmpdimx:1,
        dimy = tmpdimy?tmpdimy:1;
      if (_width!=dimx || _height!=dimy || _window_width!=dimx || _window_height!=dimy) {
        show();
        X11_attr.lock();
        if (_window_width!=dimx || _window_height!=dimy) {
          XWindowAttributes attr;
          for (unsigned int i = 0; i<10; ++i) {
            XResizeWindow(dpy,_window,dimx,dimy);
            XGetWindowAttributes(dpy,_window,&attr);
            if (attr.width==(int)dimx && attr.height==(int)dimy) break;
            cimg::wait(5,&_timer);
          }
        }
        if (_width!=dimx || _height!=dimy) switch (X11_attr.nb_bits) {
          case 8 :  { unsigned char pixel_type = 0; _resize(pixel_type,dimx,dimy,force_redraw); } break;
          case 16 : { unsigned short pixel_type = 0; _resize(pixel_type,dimx,dimy,force_redraw); } break;
          default : { unsigned int pixel_type = 0; _resize(pixel_type,dimx,dimy,force_redraw); }
          }
        _window_width = _width = dimx; _window_height = _height = dimy;
        X11_attr.unlock();
      }
      _is_resized = false;
      if (_is_fullscreen) move((screen_width() - _width)/2,(screen_height() - _height)/2);
      if (force_redraw) return paint();
      return *this;
    }

    CImgDisplay& toggle_fullscreen(const bool force_redraw=true) {
      if (is_empty()) return *this;
      if (force_redraw) {
        cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
        const cimg_ulong buf_size = (cimg_ulong)_width*_height*(X11_attr.nb_bits==8?1:(X11_attr.nb_bits==16?2:4));
        void *image_data = std::malloc(buf_size);
        std::memcpy(image_data,_data,buf_size);
        assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
        std::memcpy(_data,image_data,buf_size);
        std::free(image_data);
        return paint();
      }
      return assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
    }

    CImgDisplay& show() {
      if (is_empty() || !_is_closed) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      X11_attr.lock();
      _is_closed = false;
      if (_is_fullscreen) _init_fullscreen();
      _map_window();
      X11_attr.unlock();
      return paint();
    }

    CImgDisplay& close() {
      if (is_empty() || _is_closed) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      X11_attr.lock();
      if (_is_fullscreen) _desinit_fullscreen();
      XUnmapWindow(dpy,_window);
      _window_x = _window_y = cimg::type<int>::min();
      _is_closed = true;
      X11_attr.unlock();
      return *this;
    }

    CImgDisplay& move(const int posx, const int posy) {
      if (is_empty()) return *this;
      show();
      if (_window_x!=posx || _window_y!=posy) {
        cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
        Display *const dpy = X11_attr.display;
        X11_attr.lock();
        XMoveWindow(dpy,_window,posx,posy);
        _window_x = posx;
        _window_y = posy;
        X11_attr.unlock();
      }
      _is_moved = false;
      return paint();
    }

    CImgDisplay& show_mouse() {
      if (is_empty()) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      X11_attr.lock();
      XUndefineCursor(dpy,_window);
      X11_attr.unlock();
      return *this;
    }

    CImgDisplay& hide_mouse() {
      if (is_empty()) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      X11_attr.lock();
      static const char pix_data[8] = {};
      XColor col;
      col.red = col.green = col.blue = 0;
      Pixmap pix = XCreateBitmapFromData(dpy,_window,pix_data,8,8);
      Cursor cur = XCreatePixmapCursor(dpy,pix,pix,&col,&col,0,0);
      XFreePixmap(dpy,pix);
      XDefineCursor(dpy,_window,cur);
      X11_attr.unlock();
      return *this;
    }

    CImgDisplay& set_mouse(const int posx, const int posy) {
      if (is_empty() || _is_closed) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      X11_attr.lock();
      XWarpPointer(dpy,0L,_window,0,0,0,0,posx,posy);
      _mouse_x = posx; _mouse_y = posy;
      _is_moved = false;
      XSync(dpy,0);
      X11_attr.unlock();
      return *this;
    }

    CImgDisplay& set_title(const char *const format, ...) {
      if (is_empty()) return *this;
      char *const tmp = new char[1024];
      va_list ap;
      va_start(ap, format);
      cimg_vsnprintf(tmp,1024,format,ap);
      va_end(ap);
      if (!std::strcmp(_title,tmp)) { delete[] tmp; return *this; }
      delete[] _title;
      const unsigned int s = (unsigned int)std::strlen(tmp) + 1;
      _title = new char[s];
      std::memcpy(_title,tmp,s*sizeof(char));

      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *const dpy = X11_attr.display;
      X11_attr.lock();
      XStoreName(dpy,_window,tmp);
      X11_attr.unlock();
      delete[] tmp;
      return *this;
    }

    template<typename T>
    CImgDisplay& display(const CImg<T>& img) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "display(): Empty specified image.",
                                    cimgdisplay_instance);
      if (is_empty()) return assign(img);
      return render(img).paint(false);
    }

    CImgDisplay& paint(const bool wait_expose=true) {
      if (is_empty()) return *this;
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      X11_attr.lock();
      _paint(wait_expose);
      X11_attr.unlock();
      return *this;
    }

    template<typename T>
    CImgDisplay& render(const CImg<T>& img, const bool flag8=false) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "render(): Empty specified image.",
                                    cimgdisplay_instance);
      if (is_empty()) return *this;
      if (img._depth!=1) return render(img.get_projections2d((img._width - 1)/2,(img._height - 1)/2,
                                                             (img._depth - 1)/2));

      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      if (X11_attr.nb_bits==8 && (img._width!=_width || img._height!=_height))
        return render(img.get_resize(_width,_height,1,-100,1));
      if (X11_attr.nb_bits==8 && !flag8 && img._spectrum==3) {
        static const CImg<typename CImg<T>::ucharT> default_colormap = CImg<typename CImg<T>::ucharT>::default_LUT256();
        return render(img.get_index(default_colormap,1,false));
      }

      const T
        *data1 = img._data,
        *data2 = (img._spectrum>1)?img.data(0,0,0,1):data1,
        *data3 = (img._spectrum>2)?img.data(0,0,0,2):data1;

      if (X11_attr.is_blue_first) cimg::swap(data1,data3);
      X11_attr.lock();

      if (!_normalization || (_normalization==3 && cimg::type<T>::string()==cimg::type<unsigned char>::string())) {
        _min = _max = 0;
        switch (X11_attr.nb_bits) {
        case 8 : { // 256 colormap, no normalization
          _set_colormap(_colormap,img._spectrum);
          unsigned char
            *const ndata = (img._width==_width && img._height==_height)?(unsigned char*)_data:
            new unsigned char[(size_t)img._width*img._height],
            *ptrd = (unsigned char*)ndata;
          switch (img._spectrum) {
          case 1 :
            for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
              (*ptrd++) = (unsigned char)*(data1++);
            break;
          case 2 : for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
              const unsigned char
                R = (unsigned char)*(data1++),
                G = (unsigned char)*(data2++);
              (*ptrd++) = (R&0xf0) | (G>>4);
            } break;
          default : for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
              const unsigned char
                R = (unsigned char)*(data1++),
                G = (unsigned char)*(data2++),
                B = (unsigned char)*(data3++);
              (*ptrd++) = (R&0xe0) | ((G>>5)<<2) | (B>>6);
            }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned char*)_data,_width,_height);
            delete[] ndata;
          }
        } break;
        case 16 : { // 16 bits colors, no normalization
          unsigned short *const ndata = (img._width==_width && img._height==_height)?(unsigned short*)_data:
            new unsigned short[(size_t)img._width*img._height];
          unsigned char *ptrd = (unsigned char*)ndata;
          const unsigned int M = 248;
          switch (img._spectrum) {
          case 1 :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char val = (unsigned char)*(data1++), G = val>>2;
                ptrd[0] = (val&M) | (G>>3);
                ptrd[1] = (G<<5) | (G>>1);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char val = (unsigned char)*(data1++), G = val>>2;
                ptrd[0] = (G<<5) | (G>>1);
                ptrd[1] = (val&M) | (G>>3);
                ptrd+=2;
              }
            break;
          case 2 :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)*(data2++)>>2;
                ptrd[0] = ((unsigned char)*(data1++)&M) | (G>>3);
                ptrd[1] = (G<<5);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)*(data2++)>>2;
                ptrd[0] = (G<<5);
                ptrd[1] = ((unsigned char)*(data1++)&M) | (G>>3);
                ptrd+=2;
              }
            break;
          default :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)*(data2++)>>2;
                ptrd[0] = ((unsigned char)*(data1++)&M) | (G>>3);
                ptrd[1] = (G<<5) | ((unsigned char)*(data3++)>>3);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)*(data2++)>>2;
                ptrd[0] = (G<<5) | ((unsigned char)*(data3++)>>3);
                ptrd[1] = ((unsigned char)*(data1++)&M) | (G>>3);
                ptrd+=2;
              }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned short*)_data,_width,_height);
            delete[] ndata;
          }
        } break;
        default : { // 24 bits colors, no normalization
          unsigned int *const ndata = (img._width==_width && img._height==_height)?(unsigned int*)_data:
            new unsigned int[(size_t)img._width*img._height];
          if (sizeof(int)==4) { // 32 bits int uses optimized version
            unsigned int *ptrd = ndata;
            switch (img._spectrum) {
            case 1 :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  const unsigned char val = (unsigned char)*(data1++);
                  *(ptrd++) = (val<<16) | (val<<8) | val;
                }
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                 const unsigned char val = (unsigned char)*(data1++);
                  *(ptrd++) = (val<<16) | (val<<8) | val;
                }
              break;
            case 2 :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) = ((unsigned char)*(data1++)<<16) | ((unsigned char)*(data2++)<<8);
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) = ((unsigned char)*(data2++)<<16) | ((unsigned char)*(data1++)<<8);
              break;
            default :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) = ((unsigned char)*(data1++)<<16) | ((unsigned char)*(data2++)<<8) |
                    (unsigned char)*(data3++);
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) = ((unsigned char)*(data3++)<<24) | ((unsigned char)*(data2++)<<16) |
                    ((unsigned char)*(data1++)<<8);
            }
          } else {
            unsigned char *ptrd = (unsigned char*)ndata;
            switch (img._spectrum) {
            case 1 :
              if (X11_attr.byte_order)
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = 0;
                  ptrd[1] = (unsigned char)*(data1++);
                  ptrd[2] = 0;
                  ptrd[3] = 0;
                  ptrd+=4;
                } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = 0;
                  ptrd[1] = 0;
                  ptrd[2] = (unsigned char)*(data1++);
                  ptrd[3] = 0;
                  ptrd+=4;
                }
              break;
            case 2 :
              if (X11_attr.byte_order) cimg::swap(data1,data2);
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                ptrd[0] = 0;
                ptrd[1] = (unsigned char)*(data2++);
                ptrd[2] = (unsigned char)*(data1++);
                ptrd[3] = 0;
                ptrd+=4;
              }
              break;
            default :
              if (X11_attr.byte_order)
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = 0;
                  ptrd[1] = (unsigned char)*(data1++);
                  ptrd[2] = (unsigned char)*(data2++);
                  ptrd[3] = (unsigned char)*(data3++);
                  ptrd+=4;
                } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = (unsigned char)*(data3++);
                  ptrd[1] = (unsigned char)*(data2++);
                  ptrd[2] = (unsigned char)*(data1++);
                  ptrd[3] = 0;
                  ptrd+=4;
                }
            }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned int*)_data,_width,_height);
            delete[] ndata;
          }
        }
        }
      } else {
        if (_normalization==3) {
          if (sizeof(T)>1 && cimg::type<T>::string()!=cimg::type<bool>::string()) _min = (float)img.min_max(_max);
          else { _min = (float)cimg::type<T>::min(); _max = (float)cimg::type<T>::max(); }
        } else if ((_min>_max) || _normalization==1) _min = (float)img.min_max(_max);
        const float delta = _max - _min, mm = 255/(delta?delta:1.f);
        switch (X11_attr.nb_bits) {
        case 8 : { // 256 colormap, with normalization
          _set_colormap(_colormap,img._spectrum);
          unsigned char *const ndata = (img._width==_width && img._height==_height)?(unsigned char*)_data:
            new unsigned char[(size_t)img._width*img._height];
          unsigned char *ptrd = (unsigned char*)ndata;
          switch (img._spectrum) {
          case 1 : for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
              const unsigned char R = (unsigned char)((*(data1++) - _min)*mm);
              *(ptrd++) = R;
            } break;
          case 2 : for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
              const unsigned char
                R = (unsigned char)((*(data1++) - _min)*mm),
                G = (unsigned char)((*(data2++) - _min)*mm);
            (*ptrd++) = (R&0xf0) | (G>>4);
          } break;
          default :
            for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
              const unsigned char
                R = (unsigned char)((*(data1++) - _min)*mm),
                G = (unsigned char)((*(data2++) - _min)*mm),
                B = (unsigned char)((*(data3++) - _min)*mm);
              *(ptrd++) = (R&0xe0) | ((G>>5)<<2) | (B>>6);
            }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned char*)_data,_width,_height);
            delete[] ndata;
          }
        } break;
        case 16 : { // 16 bits colors, with normalization
          unsigned short *const ndata = (img._width==_width && img._height==_height)?(unsigned short*)_data:
            new unsigned short[(size_t)img._width*img._height];
          unsigned char *ptrd = (unsigned char*)ndata;
          const unsigned int M = 248;
          switch (img._spectrum) {
          case 1 :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char val = (unsigned char)((*(data1++) - _min)*mm), G = val>>2;
                ptrd[0] = (val&M) | (G>>3);
                ptrd[1] = (G<<5) | (val>>3);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char val = (unsigned char)((*(data1++) - _min)*mm), G = val>>2;
                ptrd[0] = (G<<5) | (val>>3);
                ptrd[1] = (val&M) | (G>>3);
                ptrd+=2;
              }
            break;
          case 2 :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)((*(data2++) - _min)*mm)>>2;
                ptrd[0] = ((unsigned char)((*(data1++) - _min)*mm)&M) | (G>>3);
                ptrd[1] = (G<<5);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)((*(data2++) - _min)*mm)>>2;
                ptrd[0] = (G<<5);
                ptrd[1] = ((unsigned char)((*(data1++) - _min)*mm)&M) | (G>>3);
                ptrd+=2;
              }
            break;
          default :
            if (X11_attr.byte_order)
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)((*(data2++) - _min)*mm)>>2;
                ptrd[0] = ((unsigned char)((*(data1++) - _min)*mm)&M) | (G>>3);
                ptrd[1] = (G<<5) | ((unsigned char)((*(data3++) - _min)*mm)>>3);
                ptrd+=2;
              } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                const unsigned char G = (unsigned char)((*(data2++) - _min)*mm)>>2;
                ptrd[0] = (G<<5) | ((unsigned char)((*(data3++) - _min)*mm)>>3);
                ptrd[1] = ((unsigned char)((*(data1++) - _min)*mm)&M) | (G>>3);
                ptrd+=2;
              }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned short*)_data,_width,_height);
            delete[] ndata;
          }
        } break;
        default : { // 24 bits colors, with normalization
          unsigned int *const ndata = (img._width==_width && img._height==_height)?(unsigned int*)_data:
            new unsigned int[(size_t)img._width*img._height];
          if (sizeof(int)==4) { // 32 bits int uses optimized version
            unsigned int *ptrd = ndata;
            switch (img._spectrum) {
            case 1 :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
                  *(ptrd++) = (val<<16) | (val<<8) | val;
                }
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
                  *(ptrd++) = (val<<24) | (val<<16) | (val<<8);
                }
              break;
            case 2 :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) =
                    ((unsigned char)((*(data1++) - _min)*mm)<<16) |
                    ((unsigned char)((*(data2++) - _min)*mm)<<8);
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) =
                    ((unsigned char)((*(data2++) - _min)*mm)<<16) |
                    ((unsigned char)((*(data1++) - _min)*mm)<<8);
              break;
            default :
              if (X11_attr.byte_order==cimg::endianness())
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) =
                    ((unsigned char)((*(data1++) - _min)*mm)<<16) |
                    ((unsigned char)((*(data2++) - _min)*mm)<<8) |
                    (unsigned char)((*(data3++) - _min)*mm);
              else
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy)
                  *(ptrd++) =
                    ((unsigned char)((*(data3++) - _min)*mm)<<24) |
                    ((unsigned char)((*(data2++) - _min)*mm)<<16) |
                    ((unsigned char)((*(data1++) - _min)*mm)<<8);
            }
          } else {
            unsigned char *ptrd = (unsigned char*)ndata;
            switch (img._spectrum) {
            case 1 :
              if (X11_attr.byte_order)
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
                  ptrd[0] = 0;
                  ptrd[1] = val;
                  ptrd[2] = val;
                  ptrd[3] = val;
                  ptrd+=4;
                } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
                  ptrd[0] = val;
                  ptrd[1] = val;
                  ptrd[2] = val;
                  ptrd[3] = 0;
                  ptrd+=4;
                }
              break;
            case 2 :
              if (X11_attr.byte_order) cimg::swap(data1,data2);
              for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                ptrd[0] = 0;
                ptrd[1] = (unsigned char)((*(data2++) - _min)*mm);
                ptrd[2] = (unsigned char)((*(data1++) - _min)*mm);
                ptrd[3] = 0;
                ptrd+=4;
              }
              break;
            default :
              if (X11_attr.byte_order)
                for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = 0;
                  ptrd[1] = (unsigned char)((*(data1++) - _min)*mm);
                  ptrd[2] = (unsigned char)((*(data2++) - _min)*mm);
                  ptrd[3] = (unsigned char)((*(data3++) - _min)*mm);
                  ptrd+=4;
                } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
                  ptrd[0] = (unsigned char)((*(data3++) - _min)*mm);
                  ptrd[1] = (unsigned char)((*(data2++) - _min)*mm);
                  ptrd[2] = (unsigned char)((*(data1++) - _min)*mm);
                  ptrd[3] = 0;
                  ptrd+=4;
                }
            }
          }
          if (ndata!=_data) {
            _render_resize(ndata,img._width,img._height,(unsigned int*)_data,_width,_height);
            delete[] ndata;
          }
        }
        }
      }
      X11_attr.unlock();
      return *this;
    }

    template<typename T>
    static void screenshot(const int x0, const int y0, const int x1, const int y1, CImg<T>& img) {
      img.assign();
      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      Display *dpy = X11_attr.display;
      X11_attr.lock();
      if (!dpy) {
        dpy = XOpenDisplay(0);
        if (!dpy)
          throw CImgDisplayException("CImgDisplay::screenshot(): Failed to open X11 display.");
      }
      Window root = DefaultRootWindow(dpy);
      XWindowAttributes gwa;
      XGetWindowAttributes(dpy,root,&gwa);
      const int width = gwa.width, height = gwa.height;
      int _x0 = x0, _y0 = y0, _x1 = x1, _y1 = y1;
      if (_x0>_x1) cimg::swap(_x0,_x1);
      if (_y0>_y1) cimg::swap(_y0,_y1);

      XImage *image = 0;
      if (_x1>=0 && _x0<width && _y1>=0 && _y0<height) {
        _x0 = std::max(_x0,0);
        _y0 = std::max(_y0,0);
        _x1 = std::min(_x1,width - 1);
        _y1 = std::min(_y1,height - 1);
        image = XGetImage(dpy,root,_x0,_y0,_x1 - _x0 + 1,_y1 - _y0 + 1,AllPlanes,ZPixmap);

        if (image) {
          const unsigned long
            red_mask = image->red_mask,
            green_mask = image->green_mask,
            blue_mask = image->blue_mask;
          img.assign(image->width,image->height,1,3);
          T *pR = img.data(0,0,0,0), *pG = img.data(0,0,0,1), *pB = img.data(0,0,0,2);
          cimg_forXY(img,x,y) {
            const unsigned long pixel = XGetPixel(image,x,y);
            *(pR++) = (T)((pixel & red_mask)>>16);
            *(pG++) = (T)((pixel & green_mask)>>8);
            *(pB++) = (T)(pixel & blue_mask);
          }
          XDestroyImage(image);
        }
      }
      if (!X11_attr.display) XCloseDisplay(dpy);
      X11_attr.unlock();
      if (img.is_empty())
        throw CImgDisplayException("CImgDisplay::screenshot(): Failed to take screenshot "
                                   "with coordinates (%d,%d)-(%d,%d).",
                                   x0,y0,x1,y1);
    }

    template<typename T>
    const CImgDisplay& snapshot(CImg<T>& img) const {
      if (is_empty()) { img.assign(); return *this; }
      const unsigned char *ptrs = (unsigned char*)_data;
      img.assign(_width,_height,1,3);
      T
        *data1 = img.data(0,0,0,0),
        *data2 = img.data(0,0,0,1),
        *data3 = img.data(0,0,0,2);

      cimg::X11_attr &X11_attr = cimg::X11_attr::ref();
      if (X11_attr.is_blue_first) cimg::swap(data1,data3);
      switch (X11_attr.nb_bits) {
      case 8 : {
        for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
          const unsigned char val = *(ptrs++);
          *(data1++) = (T)(val&0xe0);
          *(data2++) = (T)((val&0x1c)<<3);
          *(data3++) = (T)(val<<6);
        }
      } break;
      case 16 : {
        if (X11_attr.byte_order) for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
          const unsigned char
            val0 = ptrs[0],
            val1 = ptrs[1];
          ptrs+=2;
          *(data1++) = (T)(val0&0xf8);
          *(data2++) = (T)((val0<<5) | ((val1&0xe0)>>5));
          *(data3++) = (T)(val1<<3);
          } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
          const unsigned short
            val0 = ptrs[0],
            val1 = ptrs[1];
          ptrs+=2;
          *(data1++) = (T)(val1&0xf8);
          *(data2++) = (T)((val1<<5) | ((val0&0xe0)>>5));
          *(data3++) = (T)(val0<<3);
        }
      } break;
      default : {
        if (X11_attr.byte_order) for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
          ++ptrs;
          *(data1++) = (T)ptrs[0];
          *(data2++) = (T)ptrs[1];
          *(data3++) = (T)ptrs[2];
          ptrs+=3;
          } else for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            *(data3++) = (T)ptrs[0];
            *(data2++) = (T)ptrs[1];
            *(data1++) = (T)ptrs[2];
            ptrs+=3;
            ++ptrs;
          }
      }
      }
      return *this;
    }

    // GDI32-based implementation.
    //----------------------------
#elif cimg_display==2

    bool _is_mouse_tracked, _is_cursor_visible;
    HANDLE _thread, _is_created, _mutex;
    HWND _window, _background_window;
    CLIENTCREATESTRUCT _ccs;
    unsigned int *_data;
    DEVMODE _curr_mode;
    BITMAPINFO _bmi;
    HDC _hdc;

    // Internal functions.
    CImgDisplay& _assign(const unsigned int dimw, const unsigned int dimh, const char *const p_title=0,
                         const unsigned int normalization_type=3,
                         const bool is_fullscreen=false, const bool closed_flag=false) {

      // Allocate space for window title.
      const char *const np_title = p_title?p_title:"";
      const unsigned int s = (unsigned int)std::strlen(np_title) + 1;
      char *const tmp_title = s?new char[s]:0;
      if (s) std::memcpy(tmp_title,np_title,s*sizeof(char));

      // Destroy previous window if existing.
      if (!is_empty()) assign();

      // Set display variables.
      _width = std::min(dimw,(unsigned int)screen_width());
      _height = std::min(dimh,(unsigned int)screen_height());
      _normalization = normalization_type<4?normalization_type:3;
      _is_fullscreen = is_fullscreen;
      _window_x = _window_y = cimg::type<int>::min();
      _is_closed = closed_flag;
      _is_cursor_visible = true;
      _is_mouse_tracked = false;
      _title = tmp_title;
      flush();
      if (_is_fullscreen) _init_fullscreen();

      // Create event thread.
      void *const arg = (void*)(new void*[2]);
      ((void**)arg)[0] = (void*)this;
      ((void**)arg)[1] = (void*)_title;
      _mutex = CreateMutex(0,FALSE_WIN,0);
      _is_created = CreateEvent(0,FALSE_WIN,FALSE_WIN,0);
      _thread = CreateThread(0,0,_events_thread,arg,0,0);
      WaitForSingleObject(_is_created,INFINITE);
      return *this;
    }

    void _desinit_fullscreen() {
      if (!_is_fullscreen) return;
      if (_background_window) DestroyWindow(_background_window);
      _background_window = 0;
      if (_curr_mode.dmSize) ChangeDisplaySettings(&_curr_mode,0);
      _is_fullscreen = false;
    }

    static DWORD WINAPI _events_thread(void* arg) {
      CImgDisplay *const disp = (CImgDisplay*)(((void**)arg)[0]);
      const char *const title = (const char*)(((void**)arg)[1]);
      MSG msg;
      delete[] (void**)arg;
      disp->_bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
      disp->_bmi.bmiHeader.biWidth = disp->width();
      disp->_bmi.bmiHeader.biHeight = -disp->height();
      disp->_bmi.bmiHeader.biPlanes = 1;
      disp->_bmi.bmiHeader.biBitCount = 32;
      disp->_bmi.bmiHeader.biCompression = BI_RGB;
      disp->_bmi.bmiHeader.biSizeImage = 0;
      disp->_bmi.bmiHeader.biXPelsPerMeter = 1;
      disp->_bmi.bmiHeader.biYPelsPerMeter = 1;
      disp->_bmi.bmiHeader.biClrUsed = 0;
      disp->_bmi.bmiHeader.biClrImportant = 0;
      disp->_data = new unsigned int[(size_t)disp->_width*disp->_height];
      if (!disp->_is_fullscreen) { // Normal window
        RECT rect;
        rect.left = rect.top = 0; rect.right = (LONG)disp->_width - 1; rect.bottom = (LONG)disp->_height - 1;
        AdjustWindowRect(&rect,WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX,false);
        const int
          border1 = (int)((rect.right - rect.left + 1 - disp->_width)/2),
          border2 = (int)(rect.bottom - rect.top + 1 - disp->_height - border1),
          ww = disp->width() + 2*border1,
          wh = disp->height() + border1 + border2,
          sw = CImgDisplay::screen_width(),
          sh = CImgDisplay::screen_height();
        int
          wx = (int)cimg::round(cimg::rand(0,sw - ww -1)),
          wy = (int)cimg::round(cimg::rand(64,sh - wh - 65));
        if (wx + ww>=sw) wx = sw - ww;
        if (wy + wh>=sh) wy = sh - wh;
        if (wx<0) wx = 0;
        if (wy<0) wy = 0;
        disp->_window = CreateWindowA("MDICLIENT",title?title:" ",
                                      (DWORD)(WS_OVERLAPPEDWINDOW | (disp->_is_closed?0:WS_VISIBLE)),
                                      wx,wy,ww,wh,0,0,0,&(disp->_ccs));
        if (!disp->_is_closed) {
          GetWindowRect(disp->_window,&rect);
          disp->_window_x = rect.left;
          disp->_window_y = rect.top;
        } else disp->_window_x = disp->_window_y = cimg::type<int>::min();
      } else { // Fullscreen window
        const unsigned int
          sx = (unsigned int)screen_width(),
          sy = (unsigned int)screen_height();
        disp->_window = CreateWindowA("MDICLIENT",title?title:" ",
                                      (DWORD)(WS_POPUP | (disp->_is_closed?0:WS_VISIBLE)),
                                      (int)(sx - disp->_width)/2,
                                      (int)(sy - disp->_height)/2,
                                      disp->width(),disp->height(),0,0,0,&(disp->_ccs));
        disp->_window_x = disp->_window_y = 0;
      }
      SetForegroundWindow(disp->_window);
      disp->_hdc = GetDC(disp->_window);
      disp->_window_width = disp->_width;
      disp->_window_height = disp->_height;
      disp->flush();
#ifdef _WIN64
      SetWindowLongPtr(disp->_window,GWLP_USERDATA,(LONG_PTR)disp);
      SetWindowLongPtr(disp->_window,GWLP_WNDPROC,(LONG_PTR)_process_event);
#else
      SetWindowLong(disp->_window,GWL_USERDATA,(LONG)disp);
      SetWindowLong(disp->_window,GWL_WNDPROC,(LONG)_process_event);
#endif
      SetEvent(disp->_is_created);
      while (GetMessage(&msg,0,0,0)) DispatchMessage(&msg);
      return 0;
    }

    void _init_fullscreen() {
      _background_window = 0;
      if (!_is_fullscreen || _is_closed) _curr_mode.dmSize = 0;
      else {
/*        DEVMODE mode;
        unsigned int imode = 0, ibest = 0, bestbpp = 0, bw = ~0U, bh = ~0U;
        for (mode.dmSize = sizeof(DEVMODE), mode.dmDriverExtra = 0; EnumDisplaySettings(0,imode,&mode); ++imode) {
          const unsigned int nw = mode.dmPelsWidth, nh = mode.dmPelsHeight;
          if (nw>=_width && nh>=_height && mode.dmBitsPerPel>=bestbpp && nw<=bw && nh<=bh) {
            bestbpp = mode.dmBitsPerPel;
            ibest = imode;
            bw = nw; bh = nh;
          }
        }
        if (bestbpp) {
          _curr_mode.dmSize = sizeof(DEVMODE); _curr_mode.dmDriverExtra = 0;
          EnumDisplaySettings(0,ENUM_CURRENT_SETTINGS,&_curr_mode);
          EnumDisplaySettings(0,ibest,&mode);
          ChangeDisplaySettings(&mode,0);
        } else _curr_mode.dmSize = 0;
*/
        _curr_mode.dmSize = 0;
        const unsigned int
          sx = (unsigned int)screen_width(),
          sy = (unsigned int)screen_height();
        if (sx!=_width || sy!=_height) {
          CLIENTCREATESTRUCT background_ccs = { 0,0 };
          _background_window = CreateWindowA("MDICLIENT","",WS_POPUP | WS_VISIBLE,
                                             0,0,(int)sx,(int)sy,0,0,0,&background_ccs);
          SetForegroundWindow(_background_window);
        }
      }
    }

    static LRESULT APIENTRY _process_event(HWND window, UINT msg, WPARAM wParam, LPARAM lParam) {
#ifdef _WIN64
      CImgDisplay *const disp = (CImgDisplay*)GetWindowLongPtr(window,GWLP_USERDATA);
#else
      CImgDisplay *const disp = (CImgDisplay*)GetWindowLong(window,GWL_USERDATA);
#endif
      MSG st_msg;
      switch (msg) {
      case WM_CLOSE :
        disp->_mouse_x = disp->_mouse_y = -1;
        disp->_window_x = disp->_window_y = cimg::type<int>::min();
        disp->set_button().set_key(0).set_key(0,false)._is_closed = true;
        ReleaseMutex(disp->_mutex);
        ShowWindow(disp->_window,SW_HIDE);
        disp->_is_event = true;
        SetEvent(cimg::Win32_attr::ref().wait_event);
        return 0;
      case WM_SIZE : {
        while (PeekMessage(&st_msg,window,WM_SIZE,WM_SIZE,PM_REMOVE)) {}
        WaitForSingleObject(disp->_mutex,INFINITE);
        const unsigned int nw = LOWORD(lParam),nh = HIWORD(lParam);
        if (nw && nh && (nw!=disp->_width || nh!=disp->_height)) {
          disp->_window_width = nw;
          disp->_window_height = nh;
          disp->_mouse_x = disp->_mouse_y = -1;
          disp->_is_resized = disp->_is_event = true;
          SetEvent(cimg::Win32_attr::ref().wait_event);
        }
        ReleaseMutex(disp->_mutex);
      } break;
      case WM_MOVE : {
        while (PeekMessage(&st_msg,window,WM_SIZE,WM_SIZE,PM_REMOVE)) {}
        WaitForSingleObject(disp->_mutex,INFINITE);
        const int nx = (int)(short)(LOWORD(lParam)), ny = (int)(short)(HIWORD(lParam));
        if (nx!=disp->_window_x || ny!=disp->_window_y) {
          disp->_window_x = nx;
          disp->_window_y = ny;
          disp->_is_moved = disp->_is_event = true;
          SetEvent(cimg::Win32_attr::ref().wait_event);
        }
        ReleaseMutex(disp->_mutex);
      } break;
      case WM_PAINT :
        disp->paint();
        if (disp->_is_cursor_visible) while (ShowCursor(TRUE)<0); else while (ShowCursor(FALSE_WIN)>=0);
        break;
      case WM_ERASEBKGND :
        //        return 0;
        break;
      case WM_KEYDOWN :
        disp->set_key((unsigned int)wParam);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_KEYUP :
        disp->set_key((unsigned int)wParam,false);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_MOUSEMOVE : {
        while (PeekMessage(&st_msg,window,WM_MOUSEMOVE,WM_MOUSEMOVE,PM_REMOVE)) {}
        disp->_mouse_x = LOWORD(lParam);
        disp->_mouse_y = HIWORD(lParam);
#if (_WIN32_WINNT>=0x0400) && !defined(NOTRACKMOUSEEVENT)
        if (!disp->_is_mouse_tracked) {
          TRACKMOUSEEVENT tme;
          tme.cbSize = sizeof(TRACKMOUSEEVENT);
          tme.dwFlags = TME_LEAVE;
          tme.hwndTrack = disp->_window;
          if (TrackMouseEvent(&tme)) disp->_is_mouse_tracked = true;
        }
#endif
        if (disp->_mouse_x<0 || disp->_mouse_y<0 || disp->_mouse_x>=disp->width() || disp->_mouse_y>=disp->height())
          disp->_mouse_x = disp->_mouse_y = -1;
        disp->_is_event = true;
        SetEvent(cimg::Win32_attr::ref().wait_event);
        if (disp->_is_cursor_visible) while (ShowCursor(TRUE)<0); else while (ShowCursor(FALSE_WIN)>=0);
      } break;
      case WM_MOUSELEAVE : {
        disp->_mouse_x = disp->_mouse_y = -1;
        disp->_is_mouse_tracked = false;
        while (ShowCursor(TRUE)<0) {}
      } break;
      case WM_LBUTTONDOWN :
        disp->set_button(1);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_RBUTTONDOWN :
        disp->set_button(2);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_MBUTTONDOWN :
        disp->set_button(3);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_LBUTTONUP :
        disp->set_button(1,false);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_RBUTTONUP :
        disp->set_button(2,false);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case WM_MBUTTONUP :
        disp->set_button(3,false);
        SetEvent(cimg::Win32_attr::ref().wait_event);
        break;
      case 0x020A : // WM_MOUSEWHEEL:
        disp->set_wheel((int)((short)HIWORD(wParam))/120);
        SetEvent(cimg::Win32_attr::ref().wait_event);
      }
      return DefWindowProc(window,msg,wParam,lParam);
    }

    CImgDisplay& _update_window_pos() {
      if (_is_closed) _window_x = _window_y = cimg::type<int>::min();
      else {
        RECT rect;
        rect.left = rect.top = 0; rect.right = (LONG)_width - 1; rect.bottom = (LONG)_height - 1;
        AdjustWindowRect(&rect,WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX,false);
        GetWindowRect(_window,&rect);
        _window_x = rect.left;
        _window_y = rect.top;
      }
      return *this;
    }

    // Public functions.
    static int screen_width() {
      DEVMODE mode;
      mode.dmSize = sizeof(DEVMODE);
      mode.dmDriverExtra = 0;
      EnumDisplaySettings(0,ENUM_CURRENT_SETTINGS,&mode);
      return (int)mode.dmPelsWidth;
    }

    static int screen_height() {
      DEVMODE mode;
      mode.dmSize = sizeof(DEVMODE);
      mode.dmDriverExtra = 0;
      EnumDisplaySettings(0,ENUM_CURRENT_SETTINGS,&mode);
      return (int)mode.dmPelsHeight;
    }

    static void wait_all() {
      WaitForSingleObject(cimg::Win32_attr::ref().wait_event,INFINITE);
    }

    CImgDisplay& wait(const unsigned int milliseconds) {
      cimg::wait(milliseconds,&_timer);
      return *this;
    }

    CImgDisplay& assign() {
      if (is_empty()) return flush();
      DestroyWindow(_window);
      TerminateThread(_thread,0);
      delete[] _data;
      delete[] _title;
      _data = 0;
      _title = 0;
      if (_is_fullscreen) _desinit_fullscreen();
      _width = _height = _normalization = _window_width = _window_height = 0;
      _window_x = _window_y = cimg::type<int>::min();
      _is_fullscreen = false;
      _is_closed = true;
      _min = _max = 0;
      _title = 0;
      flush();
      return *this;
    }

    CImgDisplay& assign(const unsigned int dimw, const unsigned int dimh, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!dimw || !dimh) return assign();
      _assign(dimw,dimh,title,normalization_type,is_fullscreen,closed_flag);
      _min = _max = 0;
      std::memset(_data,0,sizeof(unsigned int)*_width*_height);
      return paint();
    }

    template<typename T>
    CImgDisplay& assign(const CImg<T>& img, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!img) return assign();
      CImg<T> tmp;
      const CImg<T>& nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                           (img._height - 1)/2,
                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return display(nimg);
    }

    template<typename T>
    CImgDisplay& assign(const CImgList<T>& list, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!list) return assign();
      CImg<T> tmp;
      const CImg<T> img = list>'x', &nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                                           (img._height - 1)/2,
                                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return display(nimg);
    }

    CImgDisplay& assign(const CImgDisplay& disp) {
      if (this==&disp) return *this;
      if (!disp) return assign();
      _assign(disp._width,disp._height,disp._title,disp._normalization,disp._is_fullscreen,disp._is_closed);
      std::memcpy(_data,disp._data,sizeof(unsigned int)*_width*_height);
      return paint();
    }

    CImgDisplay& resize(const int nwidth, const int nheight, const bool force_redraw=true) {
      if (!nwidth || !nheight || (is_empty() && (nwidth<0 || nheight<0))) return assign();
      if (is_empty()) return assign((unsigned int)nwidth,(unsigned int)nheight);
      const unsigned int
        tmpdimx = (nwidth>0)?nwidth:(-nwidth*_width/100),
        tmpdimy = (nheight>0)?nheight:(-nheight*_height/100),
        dimx = tmpdimx?tmpdimx:1,
        dimy = tmpdimy?tmpdimy:1;
      if (_width!=dimx || _height!=dimy || _window_width!=dimx || _window_height!=dimy) {
        if (_window_width!=dimx || _window_height!=dimy) {
          RECT rect; rect.left = rect.top = 0; rect.right = (LONG)dimx - 1; rect.bottom = (LONG)dimy - 1;
          AdjustWindowRect(&rect,WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX,false);
          const int cwidth = rect.right - rect.left + 1, cheight = rect.bottom - rect.top + 1;
          SetWindowPos(_window,0,0,0,cwidth,cheight,SWP_NOMOVE | SWP_NOZORDER | SWP_NOCOPYBITS);
        }
        if (_width!=dimx || _height!=dimy) {
          unsigned int *const ndata = new unsigned int[(cimg_ulong)dimx*dimy];
          if (force_redraw) _render_resize(_data,_width,_height,ndata,dimx,dimy);
          else std::memset(ndata,0x80,sizeof(unsigned int)*dimx*dimy);
          delete[] _data;
          _data = ndata;
          _bmi.bmiHeader.biWidth = (LONG)dimx;
          _bmi.bmiHeader.biHeight = -(int)dimy;
          _width = dimx;
          _height = dimy;
        }
        _window_width = dimx; _window_height = dimy;
        show();
      }
      _is_resized = false;
      if (_is_fullscreen) move((screen_width() - width())/2,(screen_height() - height())/2);
      if (force_redraw) return paint();
      return *this;
    }

    CImgDisplay& toggle_fullscreen(const bool force_redraw=true) {
      if (is_empty()) return *this;
      if (force_redraw) {
        const cimg_ulong buf_size = (cimg_ulong)_width*_height*4;
        void *odata = std::malloc(buf_size);
        if (odata) {
          std::memcpy(odata,_data,buf_size);
          assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
          std::memcpy(_data,odata,buf_size);
          std::free(odata);
        }
        return paint();
      }
      return assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
    }

    CImgDisplay& show() {
      if (is_empty() || !_is_closed) return *this;
      _is_closed = false;
      if (_is_fullscreen) _init_fullscreen();
      ShowWindow(_window,SW_SHOW);
      _update_window_pos();
      return paint();
    }

    CImgDisplay& close() {
      if (is_empty() || _is_closed) return *this;
      _is_closed = true;
      if (_is_fullscreen) _desinit_fullscreen();
      ShowWindow(_window,SW_HIDE);
      _window_x = _window_y = cimg::type<int>::min();
      return *this;
    }

    CImgDisplay& move(const int posx, const int posy) {
      if (is_empty()) return *this;
      if (_window_x!=posx || _window_y!=posy) {
        SetWindowPos(_window,0,posx,posy,0,0,SWP_NOSIZE | SWP_NOZORDER);
        _window_x = posx;
        _window_y = posy;
      }
      show();
      _is_moved = false;
      return *this;
    }

    CImgDisplay& show_mouse() {
      if (is_empty()) return *this;
      _is_cursor_visible = true;
      return *this;
    }

    CImgDisplay& hide_mouse() {
      if (is_empty()) return *this;
      _is_cursor_visible = false;
      return *this;
    }

    CImgDisplay& set_mouse(const int posx, const int posy) {
      if (is_empty() || _is_closed || posx<0 || posy<0) return *this;
      if (!_is_closed) {
        _update_window_pos();
        const int res = (int)SetCursorPos(_window_x + posx,_window_y + posy);
        if (res) { _mouse_x = posx; _mouse_y = posy; }
      }
      return *this;
    }

    CImgDisplay& set_title(const char *const format, ...) {
      if (is_empty()) return *this;
      char *const tmp = new char[1024];
      va_list ap;
      va_start(ap, format);
      cimg_vsnprintf(tmp,1024,format,ap);
      va_end(ap);
      if (!std::strcmp(_title,tmp)) { delete[] tmp; return *this; }
      delete[] _title;
      const unsigned int s = (unsigned int)std::strlen(tmp) + 1;
      _title = new char[s];
      std::memcpy(_title,tmp,s*sizeof(char));
      SetWindowTextA(_window, tmp);
      delete[] tmp;
      return *this;
    }

    template<typename T>
    CImgDisplay& display(const CImg<T>& img) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "display(): Empty specified image.",
                                    cimgdisplay_instance);
      if (is_empty()) return assign(img);
      return render(img).paint();
    }

    CImgDisplay& paint() {
      if (_is_closed) return *this;
      WaitForSingleObject(_mutex,INFINITE);
      SetDIBitsToDevice(_hdc,0,0,_width,_height,0,0,0,_height,_data,&_bmi,DIB_RGB_COLORS);
      ReleaseMutex(_mutex);
      return *this;
    }

    template<typename T>
    CImgDisplay& render(const CImg<T>& img) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "render(): Empty specified image.",
                                    cimgdisplay_instance);

      if (is_empty()) return *this;
      if (img._depth!=1) return render(img.get_projections2d((img._width - 1)/2,(img._height - 1)/2,
                                                             (img._depth - 1)/2));

      const T
        *data1 = img._data,
        *data2 = (img._spectrum>=2)?img.data(0,0,0,1):data1,
        *data3 = (img._spectrum>=3)?img.data(0,0,0,2):data1;

      WaitForSingleObject(_mutex,INFINITE);
      unsigned *ndata = 0;
      try {
        ndata = (img._width==_width && img._height==_height)?_data:
          new unsigned int[(size_t)img._width*img._height];
      } catch (...) {
        ReleaseMutex(_mutex);
        throw;
      }
      unsigned int *ptrd = ndata;

      if (!_normalization || (_normalization==3 && cimg::type<T>::string()==cimg::type<unsigned char>::string())) {
        _min = _max = 0;
        switch (img._spectrum) {
        case 1 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char val = (unsigned char)*(data1++);
            *(ptrd++) = (unsigned int)((val<<16) | (val<<8) | val);
          }
        } break;
        case 2 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)*(data1++),
              G = (unsigned char)*(data2++);
            *(ptrd++) = (unsigned int)((R<<16) | (G<<8));
          }
        } break;
        default : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)*(data1++),
              G = (unsigned char)*(data2++),
              B = (unsigned char)*(data3++);
            *(ptrd++) = (unsigned int)((R<<16) | (G<<8) | B);
          }
        }
        }
      } else {
        if (_normalization==3) {
          if (cimg::type<T>::is_float()) _min = (float)img.min_max(_max);
          else {
            _min = (float)cimg::type<T>::min();
            _max = (float)cimg::type<T>::max();
          }
        } else if ((_min>_max) || _normalization==1) _min = (float)img.min_max(_max);
        const float delta = _max - _min, mm = 255/(delta?delta:1.f);
        switch (img._spectrum) {
        case 1 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
            *(ptrd++) = (unsigned int)((val<<16) | (val<<8) | val);
          }
        } break;
        case 2 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)((*(data1++) - _min)*mm),
              G = (unsigned char)((*(data2++) - _min)*mm);
            *(ptrd++) = (unsigned int)((R<<16) | (G<<8));
          }
        } break;
        default : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)((*(data1++) - _min)*mm),
              G = (unsigned char)((*(data2++) - _min)*mm),
              B = (unsigned char)((*(data3++) - _min)*mm);
            *(ptrd++) = (unsigned int)((R<<16) | (G<<8) | B);
          }
        }
        }
      }
      if (ndata!=_data) { _render_resize(ndata,img._width,img._height,_data,_width,_height); delete[] ndata; }
      ReleaseMutex(_mutex);
      return *this;
    }

    template<typename T>
    static void screenshot(const int x0, const int y0, const int x1, const int y1, CImg<T>& img) {
      img.assign();
      HDC hScreen = GetDC(GetDesktopWindow());
      if (hScreen) {
        const int
          width = GetDeviceCaps(hScreen,HORZRES),
          height = GetDeviceCaps(hScreen,VERTRES);
        int _x0 = x0, _y0 = y0, _x1 = x1, _y1 = y1;
        if (_x0>_x1) cimg::swap(_x0,_x1);
        if (_y0>_y1) cimg::swap(_y0,_y1);
        if (_x1>=0 && _x0<width && _y1>=0 && _y0<height) {
          _x0 = std::max(_x0,0);
          _y0 = std::max(_y0,0);
          _x1 = std::min(_x1,width - 1);
          _y1 = std::min(_y1,height - 1);
          const int bw = _x1 - _x0 + 1, bh = _y1 - _y0 + 1;

          HDC hdcMem = CreateCompatibleDC(hScreen);
          if (hdcMem) {
            HBITMAP hBitmap = CreateCompatibleBitmap(hScreen,bw,bh);
            if (hBitmap) {
              HGDIOBJ hOld = SelectObject(hdcMem,hBitmap);
              if (hOld) {
                const BOOL bitblt_ok = BitBlt(hdcMem,0,0,bw,bh,hScreen,_x0,_y0,SRCCOPY);
                if (bitblt_ok) {
                  BITMAPINFOHEADER bmi;
                  bmi.biSize = sizeof(BITMAPINFOHEADER);
                  bmi.biWidth = bw;
                  bmi.biHeight = -bh;
                  bmi.biPlanes = 1;
                  bmi.biBitCount = 32;
                  bmi.biCompression = BI_RGB;
                  bmi.biSizeImage = 0;
                  bmi.biXPelsPerMeter = bmi.biYPelsPerMeter = 0;
                  bmi.biClrUsed = bmi.biClrImportant = 0;
                  unsigned char *buf = new unsigned char[4*bw*bh];
                  if (GetDIBits(hdcMem,hBitmap,0,bh,buf,(BITMAPINFO*)&bmi,DIB_RGB_COLORS)) {
                    try {
                      img.assign(bw,bh,1,3);
                      const unsigned char *ptrs = buf;
                      T *pR = img.data(0,0,0,0), *pG = img.data(0,0,0,1), *pB = img.data(0,0,0,2);
                      cimg_forXY(img,x,y) {
                        *(pR++) = (T)ptrs[2];
                        *(pG++) = (T)ptrs[1];
                        *(pB++) = (T)ptrs[0];
                        ptrs+=4;
                      }
                    } catch (...) {
                      delete[] buf;
                      SelectObject(hdcMem,hOld);
                      DeleteObject(hBitmap);
                      DeleteDC(hdcMem);
                      ReleaseDC(GetDesktopWindow(),hScreen);
                      throw;
                    }
                  }
                  delete[] buf;
                }
                SelectObject(hdcMem,hOld);
              }
              DeleteObject(hBitmap);
            }
            DeleteDC(hdcMem);
          }
        }
        ReleaseDC(GetDesktopWindow(),hScreen);
      }
      if (img.is_empty())
        throw CImgDisplayException("CImgDisplay::screenshot(): Failed to take screenshot "
                                   "with coordinates (%d,%d)-(%d,%d).",
                                   x0,y0,x1,y1);
    }

    template<typename T>
    const CImgDisplay& snapshot(CImg<T>& img) const {
      if (is_empty()) { img.assign(); return *this; }
      WaitForSingleObject(_mutex,INFINITE);
      const unsigned int *ptrs = _data;
      img.assign(_width,_height,1,3);
      T
        *data1 = img.data(0,0,0,0),
        *data2 = img.data(0,0,0,1),
        *data3 = img.data(0,0,0,2);
      for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
        const unsigned int val = *(ptrs++);
        *(data1++) = (T)(unsigned char)(val>>16);
        *(data2++) = (T)(unsigned char)((val>>8)&0xFF);
        *(data3++) = (T)(unsigned char)(val&0xFF);
      }
      ReleaseMutex(_mutex);
      return *this;
    }

    // SDL3-based implementation.
    //---------------------------
    // Note: This display system does *not* use a thread to manage events,
    // because SDL3 can retrieve and manage events only from the main thread.
#elif cimg_display==3

    SDL_Window *_window;
    SDL_Renderer *_renderer;
    SDL_Texture *_texture;
    SDL_ThreadID _thread_id; // ID of the thread that created this display
    unsigned int *_data;
    bool _is_cursor_visible, _paint_request;

    // Internal functions.
    void _assign(const unsigned int dimw, const unsigned int dimh, const char *const p_title=0,
                 const unsigned int normalization_type=3,
                 const bool is_fullscreen=false, const bool closed_flag=false) {

      // Destroy previous display window if existing.
      if (!is_empty()) assign();
      _data = new unsigned int[_width*_height];

      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();

      if (SDL3_attr.nb_cimg_displays>=512) {
        SDL3_attr.unlock();
        throw CImgDisplayException("CImgDisplay::assign(): Max number of displays (512) already opened.");
      }

      // Allocate space for window title.
      const char *const np_title = p_title?p_title:"";
      const unsigned int s = (unsigned int)std::strlen(np_title) + 1;
      char *const tmp_title = s?new char[s]:0;
      if (s) std::memcpy(tmp_title,np_title,s*sizeof(char));

      // Set display variables.
      _width = std::min(dimw,(unsigned int)screen_width());
      _height = std::min(dimh,(unsigned int)screen_height());
      _normalization = normalization_type<4?normalization_type:3;
      _is_fullscreen = is_fullscreen;
      _window_x = _window_y = cimg::type<int>::min();
      _is_closed = closed_flag;
      _is_cursor_visible = true;
      _paint_request = false;
      _title = tmp_title;
      _thread_id = SDL_GetCurrentThreadID();
      flush();

      // Create window and renderer.
      if (!SDL_CreateWindowAndRenderer(_title,(int)_width,(int)_height,
                                       SDL_WINDOW_RESIZABLE | SDL_WINDOW_INPUT_FOCUS | SDL_WINDOW_MOUSE_FOCUS |
                                       (_is_fullscreen?SDL_WINDOW_FULLSCREEN:0) |
                                       (_is_closed?SDL_WINDOW_HIDDEN:0),
                                       &_window,&_renderer)) {
        SDL3_attr.unlock();
        throw CImgDisplayException("CImgDisplay::assign(): %s",SDL_GetError());
      }
      SDL_RaiseWindow(_window);
      SDL_SetRenderDrawColor(_renderer,0,0,0,255);
      _window_width = _width;
      _window_height = _height;
      _update_window_pos();

      // Create texture.
      _texture = SDL_CreateTexture(_renderer,SDL_PIXELFORMAT_RGBA8888,SDL_TEXTUREACCESS_STREAMING,
                                   (int)_width,(int)_height);

      // Add to managed list of CImgDisplays.
      SDL3_attr.cimg_displays[SDL3_attr.nb_cimg_displays++] = this;
      SDL3_attr.unlock();
      paint();
    }

    void _process_event(const SDL_Event &event) {
      bool is_event = false;
      switch (event.type) {

        // Window events.
      case SDL_EVENT_WINDOW_CLOSE_REQUESTED:
        _is_closed = is_event = true;
        break;
      case SDL_EVENT_WINDOW_RESIZED: {
        _window_width = (unsigned int)event.window.data1;
        _window_height = (unsigned int)event.window.data2;
        _is_resized = _paint_request = is_event = true;
      } break;
      case SDL_EVENT_WINDOW_MOVED:
        _update_window_pos();
        _paint_request = is_event = true;
        break;
      case SDL_EVENT_WINDOW_FOCUS_GAINED:
      case SDL_EVENT_WINDOW_MINIMIZED:
      case SDL_EVENT_WINDOW_MAXIMIZED:
      case SDL_EVENT_WINDOW_RESTORED:
        _paint_request = is_event = true;
        break;
      case SDL_EVENT_WINDOW_OCCLUDED:
        _paint_request = true;
        break;

        // Mouse events.
      case SDL_EVENT_MOUSE_MOTION:
      case SDL_EVENT_WINDOW_MOUSE_ENTER: {
        float x,y;
        SDL_GetMouseState(&x,&y);
        if (x<0 || x>=_width || y<0 || y>=_height) {
          _mouse_x = _mouse_y = -1;
          SDL_ShowCursor();
        } else {
          _mouse_x = (int)x;
          _mouse_y = (int)y;
          if (_is_cursor_visible) SDL_ShowCursor(); else SDL_HideCursor();
        }
        is_event = true;
      } break;
      case SDL_EVENT_WINDOW_MOUSE_LEAVE:
        _mouse_x = _mouse_y = -1;
        SDL_ShowCursor();
        is_event = true;
        break;
      case SDL_EVENT_MOUSE_BUTTON_DOWN:
      case SDL_EVENT_MOUSE_BUTTON_UP: {
        SDL_MouseButtonFlags button = SDL_GetMouseState(0,0);
        _button = (button&1) | ((button&4)>>2)<<1 | ((button&2)>>1)<<2;
        is_event = true;
      } break;
      case SDL_EVENT_MOUSE_WHEEL:
        set_wheel((int)event.wheel.y);
        break;

        // Keyboard events.
      case SDL_EVENT_KEY_DOWN:
      case SDL_EVENT_KEY_UP:
        set_key((unsigned int)event.key.scancode,event.type==SDL_EVENT_KEY_DOWN);
        break;
      }
      if (is_event) { _is_event = true; }
    }

    CImgDisplay& _update_window_pos() {
      if (_is_closed) _window_x = _window_y = cimg::type<int>::min();
      else SDL_GetWindowPosition(_window,&_window_x,&_window_y);
      return *this;
    }

    // Public functions.
    static int screen_width() {
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      return SDL3_attr.mode->w;
    }

    static int screen_height() {
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      return SDL3_attr.mode->h;
    }

    static void wait_all() {
      process_events(true);
    }

    CImgDisplay& wait(const unsigned int milliseconds) {
      cimg::wait(milliseconds,&_timer);
      process_events(false);
      return *this;
    }

    // Process all events in event queue.
    static void process_events(bool wait_event) {
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      const SDL_ThreadID current_thread_id = SDL_GetCurrentThreadID();

      // Re-paint display windows from current thread if necessary.
      for (unsigned int k = 0; k<SDL3_attr.nb_cimg_displays; ++k) {
        CImgDisplay &disp = *SDL3_attr.cimg_displays[k];
        if (!disp.is_closed() && disp._paint_request && disp._thread_id==current_thread_id)
          SDL3_attr.cimg_displays[k]->paint();
      }

      // Make sure only the main thread process events.
      if (current_thread_id!=SDL3_attr.main_thread_id) {
        if (wait_event) cimg::sleep(8);
        return;
      }
      if (!wait_event) SDL3_attr.lock();

      // Dispatch global events to managed CImgDisplay instances.
      SDL_Event event;
      bool is_event, _wait_event = wait_event;
      do {
        is_event = _wait_event?SDL_WaitEvent(&event):SDL_PollEvent(&event);
        if (is_event) {
          if (event.type==SDL_EVENT_QUIT) {
            for (unsigned int k = 0; k<SDL3_attr.nb_cimg_displays; ++k) {
              CImgDisplay &disp = *SDL3_attr.cimg_displays[k];
              disp._is_closed = disp._is_event = true;
            }
          } else {
            SDL_Window *const window = SDL_GetWindowFromID(event.window.windowID);
            if (window) // Find CImgDisplay associated with event
              for (unsigned int k = 0; k<SDL3_attr.nb_cimg_displays; ++k) {
                CImgDisplay &disp = *SDL3_attr.cimg_displays[k];
                if (window==disp._window) {
                  if (!disp._is_closed) disp._process_event(event);
                  break;
                }
              }
          }
        }
        _wait_event = false;
      } while (is_event);

      if (!wait_event) SDL3_attr.unlock();
    }

    CImgDisplay& assign() {
      if (is_empty()) return flush();
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();

      // Remove display window from event thread list.
      unsigned int i;
      for (i = 0; i<SDL3_attr.nb_cimg_displays && SDL3_attr.cimg_displays[i]!=this; ++i) {}
      for ( ; i<SDL3_attr.nb_cimg_displays - 1; ++i)
        SDL3_attr.cimg_displays[i] = SDL3_attr.cimg_displays[i + 1];
      --SDL3_attr.nb_cimg_displays;

      // Destroy associated resources.
      SDL_DestroyRenderer(_renderer);
      SDL_DestroyWindow(_window);
      SDL_DestroyTexture(_texture);
      delete[] _data;
      _data = 0;
      _renderer = 0;
      _window = 0;
      _texture = 0;
      _thread_id = 0;
      _width = _height = _normalization = _window_width = _window_height = 0;
      _window_x = _window_y = cimg::type<int>::min();
      _is_fullscreen = false;
      _is_closed = true;
      _min = _max = 0;
      _is_cursor_visible = true;
      _paint_request = false;
      _title = 0;
      flush();
      SDL3_attr.unlock();
      return *this;
    }

    CImgDisplay& assign(const unsigned int dimw, const unsigned int dimh, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!dimw || !dimh) return assign();
      _assign(dimw,dimh,title,normalization_type,is_fullscreen,closed_flag);
      _min = _max = 0;
      std::memset(_data,0,sizeof(unsigned int)*_width*_height);
      return paint();
    }

    template<typename T>
    CImgDisplay& assign(const CImg<T>& img, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!img) return assign();
      CImg<T> tmp;
      const CImg<T>& nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                           (img._height - 1)/2,
                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return display(nimg);
    }

    template<typename T>
    CImgDisplay& assign(const CImgList<T>& list, const char *const title=0,
                        const unsigned int normalization_type=3,
                        const bool is_fullscreen=false, const bool closed_flag=false) {
      if (!list) return assign();
      CImg<T> tmp;
      const CImg<T> img = list>'x', &nimg = (img._depth==1)?img:(tmp=img.get_projections2d((img._width - 1)/2,
                                                                                           (img._height - 1)/2,
                                                                                           (img._depth - 1)/2));
      _assign(nimg._width,nimg._height,title,normalization_type,is_fullscreen,closed_flag);
      if (_normalization==2) _min = (float)nimg.min_max(_max);
      return display(nimg);
    }

    CImgDisplay& assign(const CImgDisplay& disp) {
      if (this==&disp) return *this;
      if (!disp) return assign();
      _assign(disp._width,disp._height,disp._title,disp._normalization,disp._is_fullscreen,disp._is_closed);
      std::memcpy(_data,disp._data,sizeof(unsigned int)*_width*_height);
      return paint();
    }

    CImgDisplay& move(const int posx, const int posy) {
      if (is_empty()) return *this;
      if (_window_x!=posx || _window_y!=posy) {
        cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
        SDL3_attr.lock();
        SDL_SetWindowPosition(_window,posx,posy);
        _window_x = posx;
        _window_y = posy;
        SDL3_attr.unlock();
      }
      show();
      _is_moved = false;
      return *this;
    }

    CImgDisplay& resize(const int nwidth, const int nheight, const bool force_redraw=true) {
      if (!nwidth || !nheight || (is_empty() && (nwidth<0 || nheight<0))) return assign();
      if (is_empty()) return assign((unsigned int)nwidth,(unsigned int)nheight);
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      const unsigned int
        tmpdimx = (nwidth>0)?nwidth:(-nwidth*_width/100),
        tmpdimy = (nheight>0)?nheight:(-nheight*_height/100),
        dimx = tmpdimx?tmpdimx:1,
        dimy = tmpdimy?tmpdimy:1;
      if (_width!=dimx || _height!=dimy || _window_width!=dimx || _window_height!=dimy) {
        if (_window_width!=dimx || _window_height!=dimy) {
          SDL_SetWindowSize(_window,(int)dimx,(int)dimy);
        }
        SDL3_attr.unlock();
        show();
        SDL3_attr.lock();
        unsigned int *const ndata = new unsigned int[(cimg_ulong)dimx*dimy];
        if (force_redraw) _render_resize(_data,_width,_height,ndata,dimx,dimy);
        else std::memset(ndata,0,sizeof(unsigned int)*dimx*dimy);
        delete[] _data;
        _data = ndata;
        _window_width = _width = dimx;
        _window_height = _height = dimy;
      }
      _is_resized = false;
      SDL3_attr.unlock();
      if (_is_fullscreen) move((screen_width() - width())/2,(screen_height() - height())/2);
      if (force_redraw) paint();
      return *this;
    }

    CImgDisplay& toggle_fullscreen(const bool force_redraw=true) {
      if (is_empty()) return *this;
      if (!force_redraw) return assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      const cimg_ulong buf_size = (cimg_ulong)_width*_height*sizeof(unsigned int);
      unsigned int *odata = new unsigned int[_width*_height];
      std::memcpy(odata,_data,buf_size);
      SDL3_attr.unlock();
      assign(_width,_height,_title,_normalization,!_is_fullscreen,false);
      cimg::swap(_data,odata);
      delete[] odata;
      return paint();
    }

    CImgDisplay& show() {
      if (is_empty() || !_is_closed) return *this;
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      _is_closed = false;
      if (_is_fullscreen) SDL_SetWindowFullscreen(_window,true);
      SDL_ShowWindow(_window);
      _update_window_pos();
      SDL3_attr.unlock();
      return paint();
    }

    CImgDisplay& close() {
      if (is_empty() || _is_closed) return *this;
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      _is_closed = true;
      if (_is_fullscreen) SDL_SetWindowFullscreen(_window,false);
      SDL_HideWindow(_window);
      _window_x = _window_y = cimg::type<int>::min();
      SDL3_attr.unlock();
      return *this;
    }

    CImgDisplay& set_title(const char *const format, ...) {
      if (is_empty()) return *this;
      char *const tmp = new char[1024];
      va_list ap;
      va_start(ap, format);
      cimg_vsnprintf(tmp,1024,format,ap);
      va_end(ap);
      if (!std::strcmp(_title,tmp)) { delete[] tmp; return *this; }

      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      delete[] _title;
      const unsigned int s = (unsigned int)std::strlen(tmp) + 1;
      _title = new char[s];
      std::memcpy(_title,tmp,s*sizeof(char));
      SDL_SetWindowTitle(_window,tmp);
      delete[] tmp;
      SDL3_attr.unlock();
      return *this;
    }

    CImgDisplay& show_mouse() {
      if (is_empty()) return *this;
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      SDL_ShowCursor();
      _is_cursor_visible = true;
      SDL3_attr.unlock();
      return *this;
    }

    CImgDisplay& hide_mouse() {
      if (is_empty()) return *this;
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      SDL_HideCursor();
      _is_cursor_visible = false;
      SDL3_attr.unlock();
      return *this;
    }

    CImgDisplay& set_mouse(const int posx, const int posy) {
      if (is_empty() || _is_closed || posx<0 || posy<0) return *this;
      if (!_is_closed) {
        cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
        SDL3_attr.lock();
        SDL_WarpMouseInWindow(_window,(float)posx,(float)posy);
        _mouse_x = posx; _mouse_y = posy;
        SDL3_attr.unlock();
      }
      return *this;
    }

    template<typename T>
    CImgDisplay& display(const CImg<T>& img) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "display(): Empty specified image.",
                                    cimgdisplay_instance);
      if (is_empty()) return assign(img);
      return render(img).paint();
    }

    CImgDisplay& paint() {
      if (_is_closed) return *this;
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();

      const SDL_ThreadID current_thread_id = SDL_GetCurrentThreadID();
      if (current_thread_id!=_thread_id) {
        // Make sure repaint is done by the thread that created the window.
        _paint_request = true;
        return *this;
      }

      SDL3_attr.lock();
      if (!_texture || _texture->w!=(int)_width || _texture->h!=(int)_height) {
        if (_texture) SDL_DestroyTexture(_texture);
        _texture = SDL_CreateTexture(_renderer,SDL_PIXELFORMAT_RGBA8888,SDL_TEXTUREACCESS_STREAMING,
                                     (int)_width,(int)_height);
      }
      SDL_UpdateTexture(_texture,0,_data,_width*sizeof(unsigned int));
      SDL_RenderClear(_renderer);
      SDL_FRect rect;
      rect.x = rect.y = 0;
      rect.w = (float)_width;
      rect.h = (float)_height;
      SDL_RenderTexture(_renderer,_texture,0,&rect);
      SDL_RenderPresent(_renderer);
      _paint_request = false;
      SDL3_attr.unlock();
      return *this;
    }

    template<typename T>
    CImgDisplay& render(const CImg<T>& img) {
      if (!img)
        throw CImgArgumentException(_cimgdisplay_instance
                                    "render(): Empty specified image.",
                                    cimgdisplay_instance);

      if (is_empty()) return *this;
      if (img._depth!=1) return render(img.get_projections2d((img._width - 1)/2,(img._height - 1)/2,
                                                             (img._depth - 1)/2));
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      const T
        *data1 = img._data,
        *data2 = (img._spectrum>=2)?img.data(0,0,0,1):data1,
        *data3 = (img._spectrum>=3)?img.data(0,0,0,2):data1;

      unsigned int *ndata = 0;
      try {
        ndata = (img._width==_width && img._height==_height)?_data:
          new unsigned int[(size_t)img._width*img._height];
      } catch (...) {
        SDL3_attr.unlock();
        throw;
      }
      unsigned int *ptrd = ndata;

      if (!_normalization || (_normalization==3 && cimg::type<T>::string()==cimg::type<unsigned char>::string())) {
        _min = _max = 0;
        switch (img._spectrum) {
        case 1 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char val = (unsigned char)*(data1++);
            *(ptrd++) = (unsigned int)((val<<24) | (val<<16) | (val<<8) | 255);
          }
        } break;
        case 2 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)*(data1++),
              G = (unsigned char)*(data2++);
            *(ptrd++) = (unsigned int)((R<<24) | (G<<16) | 255);
          }
        } break;
        default : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)*(data1++),
              G = (unsigned char)*(data2++),
              B = (unsigned char)*(data3++);
            *(ptrd++) = (unsigned int)((R<<24) | (G<<16) | (B<<8) | 255);
          }
        }
        }
      } else {
        if (_normalization==3) {
          if (cimg::type<T>::is_float()) _min = (float)img.min_max(_max);
          else {
            _min = (float)cimg::type<T>::min();
            _max = (float)cimg::type<T>::max();
          }
        } else if ((_min>_max) || _normalization==1) _min = (float)img.min_max(_max);
        const float delta = _max - _min, mm = 255/(delta?delta:1.f);
        switch (img._spectrum) {
        case 1 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char val = (unsigned char)((*(data1++) - _min)*mm);
            *(ptrd++) = (unsigned int)((val<<24) | (val<<16) | (val<<8) | 255);
          }
        } break;
        case 2 : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)((*(data1++) - _min)*mm),
              G = (unsigned char)((*(data2++) - _min)*mm);
            *(ptrd++) = (unsigned int)((R<<24) | (G<<16) | 255);
          }
        } break;
        default : {
          for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
            const unsigned char
              R = (unsigned char)((*(data1++) - _min)*mm),
              G = (unsigned char)((*(data2++) - _min)*mm),
              B = (unsigned char)((*(data3++) - _min)*mm);
            *(ptrd++) = (unsigned int)((R<<24) | (G<<16) | (B<<8) | 255);
          }
        }
        }
      }
      if (ndata!=_data) { _render_resize(ndata,img._width,img._height,_data,_width,_height); delete[] ndata; }
      SDL3_attr.unlock();

//      process_events(false);
      return *this;
    }

    template<typename T>
    static void screenshot(const int, const int, const int, const int, CImg<T>&) {
      throw CImgDisplayException("screenshot(): Screenshot feature is not supported when using SDL3-based display.");
    }

    template<typename T>
    const CImgDisplay& snapshot(CImg<T>& img) const {
      if (is_empty()) { img.assign(); return *this; }
      cimg::SDL3_attr &SDL3_attr = cimg::SDL3_attr::ref();
      SDL3_attr.lock();
      const unsigned int *ptrs = _data;
      img.assign(_width,_height,1,3);
      T
        *data1 = img.data(0,0,0,0),
        *data2 = img.data(0,0,0,1),
        *data3 = img.data(0,0,0,2);
      for (cimg_ulong xy = (cimg_ulong)img._width*img._height; xy>0; --xy) {
        const unsigned int val = *(ptrs++);
        *(data1++) = (T)(unsigned char)(val>>24);
        *(data2++) = (T)(unsigned char)((val>>16)&0xFF);
        *(data3++) = (T)(unsigned char)((val>>8)&0xFF);
      }
      SDL3_attr.unlock();
      return *this;
    }

#endif

    //@}
  }; // struct CImgDisplay { ...

  /*
   #--------------------------------------
   #
   #
   #
   # Definition of the CImg<T> structure
   #
   #
   #
   #--------------------------------------
   */

  //! Class representing an image (up to 4 dimensions wide), where each pixel is of type \c T.
  /**
     This is the main class of the \CImg Library. It declares and constructs
     an image, allows access to its pixel values, and is able to perform various image operations.

     \par Image representation

     A \CImg image is defined as an instance of the container \c CImg<T>, which contains a regular grid of pixels,
     each pixel value being of type \c T. The image grid can have up to 4 dimensions: width, height, depth
     and number of channels.
     Usually, the first three dimensions are used to describe spatial coordinates <tt>(x,y,z)</tt>,
     while the number of channels is rather used as a vector-valued dimension
     (it may describe the R,G,B color channels for instance).
     If you need a fifth dimension, you can use image lists \c CImgList<T> rather than simple images \c CImg<T>.

     Thus, the \c CImg<T> class is able to represent volumetric images of vector-valued pixels,
     as well as images with less dimensions (1D scalar signal, 2D color images, ...).
     Most member functions of the class CImg<\c T> are designed to handle this maximum case of (3+1) dimensions.

     Concerning the pixel value type \c T:
     fully supported template types are the basic C++ types: <tt>unsigned char, char, short, unsigned int, int,
     unsigned long, long, float, double, ... </tt>.
     Typically, fast image display can be done using <tt>CImg<unsigned char></tt> images,
     while complex image processing algorithms may be rather coded using <tt>CImg<float></tt> or <tt>CImg<double></tt>
     images that have floating-point pixel values. The default value for the template T is \c float.
     Using your own template types may be possible. However, you will certainly have to define the complete set
     of arithmetic and logical operators for your class.

     \par Image structure

     The \c CImg<T> structure contains \e six fields:
     - \c _width defines the number of \a columns of the image (size along the X-axis).
     - \c _height defines the number of \a rows of the image (size along the Y-axis).
     - \c _depth defines the number of \a slices of the image (size along the Z-axis).
     - \c _spectrum defines the number of \a channels of the image (size along the C-axis).
     - \c _data defines a \a pointer to the \a pixel \a data (of type \c T).
     - \c _is_shared is a boolean indicating that the memory buffer \c data is shared with
       another image.

     You can access these fields publicly although it is recommended to use the dedicated functions
     width(), height(), depth(), spectrum() and ptr() to do so.
     Image dimensions are not limited to a specific range (as long as you have enough available memory).
     A value of \e 1 usually means that the corresponding dimension is \a flat.
     If one of the dimensions is \e 0, or if the data pointer is null, the image is considered as \e empty.
     Empty images should not contain any pixel data and thus, will not be processed by CImg member functions
     (a CImgInstanceException will be thrown instead).
     Pixel data is stored in memory, in a non-interleaved mode (See \ref cimg_storage).

     \par Image declaration and construction

     Declaring an image can be done by using one of the several available constructors.
     Here is a list of the most used:

     - Construct images from arbitrary dimensions:
         - <tt>CImg<char> img;</tt> declares an empty image.
         - <tt>CImg<unsigned char> img(128,128);</tt> declares a 128x128 greyscale image with
         \c unsigned \c char pixel values.
         - <tt>CImg<double> img(3,3);</tt> declares a 3x3 matrix with \c double coefficients.
         - <tt>CImg<unsigned char> img(256,256,1,3);</tt> declares a 256x256x1x3 (color) image
         (colors are stored as an image with three channels).
         - <tt>CImg<double> img(128,128,128);</tt> declares a 128x128x128 volumetric and greyscale image
         (with \c double pixel values).
         - <tt>CImg<> img(128,128,128,3);</tt> declares a 128x128x128 volumetric color image
         (with \c float pixels, which is the default value of the template parameter \c T).
         - \b Note: images pixels are <b>not automatically initialized to 0</b>. You may use the function \c fill() to
         do it, or use the specific constructor taking 5 parameters like this:
         <tt>CImg<> img(128,128,128,3,0);</tt> declares a 128x128x128 volumetric color image with all pixel values to 0.

     - Construct images from filenames:
         - <tt>CImg<unsigned char> img("image.jpg");</tt> reads a JPEG color image from the file "image.jpg".
         - <tt>CImg<float> img("analyze.hdr");</tt> reads a volumetric image (ANALYZE7.5 format) from the
         file "analyze.hdr".
         - \b Note: You need to install <a href="http://www.imagemagick.org">ImageMagick</a>
         to be able to read common compressed image formats (JPG,PNG, ...) (See \ref cimg_files_io).

     - Construct images from C-style arrays:
         - <tt>CImg<int> img(data_buffer,256,256);</tt> constructs a 256x256 greyscale image from a \c int* buffer
         \c data_buffer (of size 256x256=65536).
         - <tt>CImg<unsigned char> img(data_buffer,256,256,1,3);</tt> constructs a 256x256 color image
         from a \c unsigned \c char* buffer \c data_buffer (where R,G,B channels follow each others).

         The complete list of constructors can be found <a href="#constructors">here</a>.

     \par Most useful functions

     The \c CImg<T> class contains a lot of functions that operate on images.
     Some of the most useful are:

     - operator()(): Read or write pixel values.
     - display(): Displays the image in a new window.
  **/
  template<typename T>
  struct CImg {

    unsigned int _width, _height, _depth, _spectrum;
    bool _is_shared;
    T *_data;

    //! Simple iterator type to loop through each pixel value of an image instance.
    /**
       \note
       - The \c CImg<T>::iterator type is defined to be a <tt>T*</tt>.
       - You will seldom have to use iterators in \CImg, most classical operations
         being achieved (often in a faster way) using functions of \c CImg<T>.
       \par Example
       \code
       CImg<float> img("reference.jpg"); // Load image from file
       // Set all pixels to '0', with a CImg iterator.
       for (CImg<float>::iterator it = img.begin(); it<img.end(); ++it) *it = 0;
       img.fill(0); // Do the same with a built-in function
       \endcode
   **/
    typedef T* iterator;

    //! Simple const iterator type, to loop through each pixel value of a \c const image instance.
    /**
       \note
       - The \c CImg<T>::const_iterator type is defined to be a \c const \c T*.
       - You will seldom have to use iterators in \CImg, most classical operations
         being achieved (often in a faster way) using functions of \c CImg<T>.
       \par Example
       \code
       const CImg<float> img("reference.jpg"); // Load image from file
       float sum = 0;
       // Compute sum of all pixel values, with a CImg iterator.
       for (CImg<float>::const_iterator it = img.begin(); it<img.end(); ++it) sum+=*it;
       const float sum2 = img.sum(); // Do the same with a built-in function
       \endcode
    **/
    typedef const T* const_iterator;

    //! Pixel value type.
    /**
       Refer to the type of the pixel values of an image instance.
       \note
       - The \c CImg<T>::value_type type of a \c CImg<T> is defined to be a \c T.
       - \c CImg<T>::value_type is actually not used in \CImg functions. It has been mainly defined for
         compatibility with STL naming conventions.
    **/
    typedef T value_type;

    // Define common types related to template type T.
    typedef typename cimg::superset<T,bool>::type Tbool;
    typedef typename cimg::superset<T,unsigned char>::type Tuchar;
    typedef typename cimg::superset<T,char>::type Tchar;
    typedef typename cimg::superset<T,unsigned short>::type Tushort;
    typedef typename cimg::superset<T,short>::type Tshort;
    typedef typename cimg::superset<T,unsigned int>::type Tuint;
    typedef typename cimg::superset<T,int>::type Tint;
    typedef typename cimg::superset<T,cimg_ulong>::type Tulong;
    typedef typename cimg::superset<T,cimg_long>::type Tlong;
    typedef typename cimg::superset<T,float>::type Tfloat;
    typedef typename cimg::superset<T,double>::type Tdouble;
    typedef typename cimg::last<T,bool>::type boolT;
    typedef typename cimg::last<T,unsigned char>::type ucharT;
    typedef typename cimg::last<T,char>::type charT;
    typedef typename cimg::last<T,unsigned short>::type ushortT;
    typedef typename cimg::last<T,short>::type shortT;
    typedef typename cimg::last<T,unsigned int>::type uintT;
    typedef typename cimg::last<T,int>::type intT;
    typedef typename cimg::last<T,cimg_ulong>::type ulongT;
    typedef typename cimg::last<T,cimg_long>::type longT;
    typedef typename cimg::last<T,cimg_uint64>::type uint64T;
    typedef typename cimg::last<T,cimg_int64>::type int64T;
    typedef typename cimg::last<T,float>::type floatT;
    typedef typename cimg::last<T,double>::type doubleT;

    // Return 'dx*dy*dz*dc' as a 'size_t' and check that no overflow occurs.
    static size_t safe_size(const unsigned int dx, const unsigned int dy,
                            const unsigned int dz, const unsigned int dc) {
      if (!(dx && dy && dz && dc)) return 0;
      size_t siz = (size_t)dx;
      const size_t max_size_t = ~((size_t)0); // Portable definition of size_t maximum value in C++98

      // Perform strict division-based overflow checks for dimensions and type size.
      if ((dy==1 || (siz<=max_size_t/dy && (siz*=dy))) &&
          (dz==1 || (siz<=max_size_t/dz && (siz*=dz))) &&
          (dc==1 || (siz<=max_size_t/dc && (siz*=dc))) &&
          (sizeof(T)==1 || siz<=max_size_t/sizeof(T))) {
        const size_t total_bytes = siz*sizeof(T);
        if (total_bytes>cimg_max_buf_size) {
          throw CImgArgumentException("CImg<%s>::safe_size(): Specified size (%u,%u,%u,%u) exceeds maximum "
                                      "allowed buffer size of %lu.",
                                      pixel_type(),dx,dy,dz,dc,cimg_max_buf_size);
        }
        return siz;
      }
      throw CImgArgumentException("CImg<%s>::safe_size(): Specified size (%u,%u,%u,%u) overflows 'size_t'.",
                                  pixel_type(),dx,dy,dz,dc);
    }

    //@}
    //---------------------------
    //
    //! \name Plugins
    //@{
    //---------------------------
#ifdef cimg_plugin
#include cimg_plugin
#endif
#ifdef cimg_plugin1
#include cimg_plugin1
#endif
#ifdef cimg_plugin2
#include cimg_plugin2
#endif
#ifdef cimg_plugin3
#include cimg_plugin3
#endif
#ifdef cimg_plugin4
#include cimg_plugin4
#endif
#ifdef cimg_plugin5
#include cimg_plugin5
#endif
#ifdef cimg_plugin6
#include cimg_plugin6
#endif
#ifdef cimg_plugin7
#include cimg_plugin7
#endif
#ifdef cimg_plugin8
#include cimg_plugin8
#endif

    //@}
    //---------------------------------------------------------
    //
    //! \name Constructors / Destructor / Instance Management
    //@{
    //---------------------------------------------------------

    //! Destroy image.
    /**
       \note
       - The pixel buffer data() is deallocated if necessary, e.g. for non-empty and non-shared image instances.
       - Destroying an empty or shared image does nothing actually.
       \warning
       - When destroying a non-shared image, make sure that you will \e not operate on a remaining shared image
         that shares its buffer with the destroyed instance, in order to avoid further invalid memory access
         (to a deallocated buffer).
    **/
    ~CImg() {
      if (!_is_shared) delete[] _data;
    }

    //! Construct empty image.
    /**
       \note
       - An empty image has no pixel data and all of its dimensions width(), height(), depth(), spectrum()
         are set to \c 0, as well as its pixel buffer pointer data().
       - An empty image may be re-assigned afterwards, e.g. with the family of
         assign(unsigned int,unsigned int,unsigned int,unsigned int) functions,
         or by operator=(const CImg<t>&). In all cases, the type of pixels stays \c T.
       - An empty image is never shared.
       \par Example
       \code
       CImg<float> img1, img2; // Construct two empty images
       img1.assign(256,256,1,3); // Re-assign 'img1' to be a 256x256x1x3 (color) image
       img2 = img1.get_rand(0,255); // Re-assign 'img2' to be a random-valued version of 'img1'
       img2.assign(); // Re-assign 'img2' to be an empty image again
       \endcode
    **/
    CImg():_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {}

    //! Construct image with specified size.
    /**
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \note
       - It can only create \e non-shared images, and allocates thus a pixel buffer data()
         for each constructed image instance.
       - Setting one dimension \c size_x,\c size_y,\c size_z or \c size_c to \c 0 leads to the construction of
         an \e empty image.
       - A \c CImgInstanceException is thrown when the pixel buffer cannot be allocated
         (e.g. when requested size is too big for available memory).
       \warning
       - The allocated pixel buffer is \e not filled with a default value, and is likely to contain garbage values.
         In order to initialize pixel values during construction (e.g. with \c 0), use constructor
         CImg(unsigned int,unsigned int,unsigned int,unsigned int,T) instead.
       \par Example
       \code
       CImg<float> img1(256,256,1,3); // Construct a 256x256x1x3 (color) image, filled with garbage values
       CImg<float> img2(256,256,1,3,0); // Construct a 256x256x1x3 (color) image, filled with value '0'
       \endcode
    **/
    explicit CImg(const unsigned int size_x, const unsigned int size_y=1,
                  const unsigned int size_z=1, const unsigned int size_c=1):
      _is_shared(false) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (siz) {
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                      size_x,size_y,size_z,size_c);
        }
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Construct image with specified size and initialize pixel values.
    /**
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param value Initialization value.
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int),
         but it also fills the pixel buffer with the specified \c value.
       \warning
       - It cannot be used to construct a vector-valued image and initialize it with \e vector-valued pixels
         (e.g. RGB vector, for color images).
         For this task, you may use fillC() after construction.
    **/
    CImg(const unsigned int size_x, const unsigned int size_y,
         const unsigned int size_z, const unsigned int size_c, const T& value):
      _is_shared(false) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (siz) {
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                      size_x,size_y,size_z,size_c);
        }
        fill(value);
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Construct image with specified size and initialize pixel values from a sequence of integers.
    /**
       Construct a new image instance of size \c size_x x \c size_y x \c size_z x \c size_c,
       with pixels of type \c T, and initialize pixel
       values from the specified sequence of integers \c value0,\c value1,\c ...
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param value0 First value of the initialization sequence (must be an \e integer).
       \param value1 Second value of the initialization sequence (must be an \e integer).
       \param ...
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int), but it also fills
         the pixel buffer with a sequence of specified integer values.
       \warning
       - You must specify \e exactly \c size_x*\c size_y*\c size_z*\c size_c integers in the initialization sequence.
         Otherwise, the constructor may crash or fill your image pixels with garbage.
       \par Example
       \code
       const CImg<float> img(2,2,1,3, // Construct a 2x2 color (RGB) image
                             0,255,0,255, // Set the 4 values for the red component
                             0,0,255,255, // Set the 4 values for the green component
                             64,64,64,64); // Set the 4 values for the blue component
       img.resize(150,150).display();
       \endcode
       \image html ref_constructor1.jpg
     **/
    CImg(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z, const unsigned int size_c,
         const int value0, const int value1, ...):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
#define _CImg_stdarg(img,a0,a1,N,t) { \
        size_t _siz = (size_t)N; \
        if (_siz--) { \
          va_list ap; \
          va_start(ap,a1); \
          T *ptrd = (img)._data; \
          *(ptrd++) = (T)a0; \
          if (_siz--) { \
            *(ptrd++) = (T)a1; \
            for ( ; _siz; --_siz) *(ptrd++) = (T)va_arg(ap,t); \
          } \
          va_end(ap); \
        } \
      }
      assign(size_x,size_y,size_z,size_c);
      _CImg_stdarg(*this,value0,value1,safe_size(size_x,size_y,size_z,size_c),int);
    }

#if cimg_use_cpp11==1
    //! Construct image with specified size and initialize pixel values from an initializer list of integers.
    /**
       Construct a new image instance of size \c size_x x \c size_y x \c size_z x \c size_c,
       with pixels of type \c T, and initialize pixel
       values from the specified initializer list of integers { \c value0,\c value1,\c ... }
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param { value0, value1, ... } Initialization list
       \param repeat_values Indicates whether the value filling process is repeated over the image.

       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int), but it also fills
         the pixel buffer with a sequence of specified integer values.
       \par Example
       \code
       const CImg<float> img(2,2,1,3, // Construct a 2x2 color (RGB) image
                             { 0,255,0,255, // Set the 4 values for the red component
                               0,0,255,255, // Set the 4 values for the green component
                               64,64,64,64 }); // Set the 4 values for the blue component
       img.resize(150,150).display();
       \endcode
       \image html ref_constructor1.jpg
    **/
    template<typename t>
    CImg(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z, const unsigned int size_c,
         const std::initializer_list<t> values,
         const bool repeat_values=true):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
#define _cimg_constructor_cpp11(repeat_values) \
  auto it = values.begin(); \
  size_t siz = size(); \
  if (repeat_values) for (T *ptrd = _data; siz--; ) { \
    *(ptrd++) = (T)(*(it++)); if (it==values.end()) it = values.begin(); } \
  else { siz = std::min(siz,values.size()); for (T *ptrd = _data; siz--; ) *(ptrd++) = (T)(*(it++)); }
      assign(size_x,size_y,size_z,size_c);
      _cimg_constructor_cpp11(repeat_values);
    }

    template<typename t>
    CImg(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z,
         std::initializer_list<t> values,
         const bool repeat_values=true):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(size_x,size_y,size_z);
      _cimg_constructor_cpp11(repeat_values);
    }

    template<typename t>
    CImg(const unsigned int size_x, const unsigned int size_y,
         std::initializer_list<t> values,
         const bool repeat_values=true):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(size_x,size_y);
      _cimg_constructor_cpp11(repeat_values);
    }

    template<typename t>
    CImg(const unsigned int size_x,
         std::initializer_list<t> values,
         const bool repeat_values=true):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(size_x);
      _cimg_constructor_cpp11(repeat_values);
    }

    //! Construct single channel 1D image with pixel values and width obtained from an initializer list of integers.
    /**
       Construct a new image instance of size \c width x \c 1 x \c 1 x \c 1,
       with pixels of type \c T, and initialize pixel
       values from the specified initializer list of integers { \c value0,\c value1,\c ... }. Image width is
       given by the size of the initializer list.
       \param { value0, value1, ... } Initialization list
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int) with height=1, depth=1, and spectrum=1,
         but it also fills the pixel buffer with a sequence of specified integer values.
       \par Example
       \code
       const CImg<float> img = {10,20,30,20,10 }; // Construct a 5x1 image with one channel, and set its pixel values
       img.resize(150,150).display();
       \endcode
       \image html ref_constructor1.jpg
     **/
    template<typename t>
    CImg(const std::initializer_list<t> values):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(values.size(),1,1,1);
      auto it = values.begin();
      unsigned int siz = _width;
      for (T *ptrd = _data; siz--; ) *(ptrd++) = (T)(*(it++));
    }

    template<typename t>
    CImg<T>& operator=(std::initializer_list<t> values) {
      _cimg_constructor_cpp11(siz>values.size());
      return *this;
    }
#endif

    //! Construct image with specified size and initialize pixel values from a sequence of doubles.
    /**
       Construct a new image instance of size \c size_x x \c size_y x \c size_z x \c size_c, with pixels of type \c T,
       and initialize pixel values from the specified sequence of doubles \c value0,\c value1,\c ...
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param value0 First value of the initialization sequence (must be a \e double).
       \param value1 Second value of the initialization sequence (must be a \e double).
       \param ...
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int,int,int,...), but
         takes a sequence of double values instead of integers.
       \warning
       - You must specify \e exactly \c dx*\c dy*\c dz*\c dc doubles in the initialization sequence.
         Otherwise, the constructor may crash or fill your image with garbage.
         For instance, the code below will probably crash on most platforms:
         \code
         const CImg<float> img(2,2,1,1, 0.5,0.5,255,255); // FAIL: The two last arguments are 'int', not 'double'!
         \endcode
     **/
    CImg(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z, const unsigned int size_c,
         const double value0, const double value1, ...):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(size_x,size_y,size_z,size_c);
      _CImg_stdarg(*this,value0,value1,safe_size(size_x,size_y,size_z,size_c),double);
    }

    //! Construct image with specified size and initialize pixel values from a value string.
    /**
       Construct a new image instance of size \c size_x x \c size_y x \c size_z x \c size_c, with pixels of type \c T,
       and initializes pixel values from the specified string \c values.
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param values Value string describing the way pixel values are set.
       \param repeat_values Indicates whether the value filling process is repeated over the image.
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int), but it also fills
         the pixel buffer with values described in the value string \c values.
       - Value string \c values may describe two different filling processes:
         - Either \c values is a sequences of values assigned to the image pixels, as in <tt>"1,2,3,7,8,2"</tt>.
           In this case, set \c repeat_values to \c true to periodically fill the image with the value sequence.
         - Either, \c values is a formula, as in <tt>"cos(x/10)*sin(y/20)"</tt>.
           In this case, parameter \c repeat_values is pointless.
       - For both cases, specifying \c repeat_values is mandatory.
         It disambiguates the possible overloading of constructor
         CImg(unsigned int,unsigned int,unsigned int,unsigned int,T) with \c T being a <tt>const char*</tt>.
       - A \c CImgArgumentException is thrown when an invalid value string \c values is specified.
       \par Example
       \code
       const CImg<float> img1(129,129,1,3,"0,64,128,192,255",true), // Construct image from a value sequence
                         img2(129,129,1,3,"if(c==0,255*abs(cos(x/10)),1.8*y)",false); // Construct image from a formula
       (img1,img2).display();
       \endcode
       \image html ref_constructor2.jpg
     **/
    CImg(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z, const unsigned int size_c,
         const char *const values, const bool repeat_values):_is_shared(false) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (siz) {
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                      size_x,size_y,size_z,size_c);
        }
        fill(values,repeat_values);
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer.
    /**
       Construct a new image instance of size \c size_x x \c size_y x \c size_z x \c size_c, with pixels of type \c T,
       and initializes pixel values from the specified \c t* memory buffer.
       \param values Pointer to the input memory buffer.
       \param size_x Image width().
       \param size_y Image height().
       \param size_z Image depth().
       \param size_c Image spectrum() (number of channels).
       \param is_shared Indicates whether input memory buffer must be shared by the current instance.
       \note
       - If \c is_shared is \c false, the image instance allocates its own pixel buffer,
         and values from the specified input buffer are copied to the instance buffer.
         If buffer types \c T and \c t are different, a regular static cast is performed during buffer copy.
       - Otherwise, the image instance does \e not allocate a new buffer, and uses the input memory buffer as its
         own pixel buffer. This case requires that types \c T and \c t are the same. Later, destroying such a shared
         image will not deallocate the pixel buffer, this task being obviously charged to the initial buffer allocator.
       - A \c CImgInstanceException is thrown when the pixel buffer cannot be allocated
         (e.g. when requested size is too big for available memory).
       \warning
       - You must take care when operating on a shared image, since it may have an invalid pixel buffer pointer data()
         (e.g. already deallocated).
       \par Example
       \code
       unsigned char tab[256*256] = {};
       CImg<unsigned char> img1(tab,256,256,1,1,false), // Construct new non-shared image from buffer 'tab'
                           img2(tab,256,256,1,1,true); // Construct new shared-image from buffer 'tab'
       tab[1024] = 255; // Here, 'img2' is indirectly modified, but not 'img1'
       \endcode
    **/
    template<typename t>
    CImg(const t *const values, const unsigned int size_x, const unsigned int size_y=1,
         const unsigned int size_z=1, const unsigned int size_c=1, const bool is_shared=false):_is_shared(false) {
      if (is_shared) {
        _width = _height = _depth = _spectrum = 0; _data = 0;
        throw CImgArgumentException(_cimg_instance
                                    "CImg(): Invalid request for constructing a (%u,%u,%u,%u) shared instance "
                                    "from a (%s*) buffer (pixel types are different).",
                                    cimg_instance,
                                    size_x,size_y,size_z,size_c,CImg<t>::pixel_type());
      }
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (values && siz) {
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                      size_x,size_y,size_z,size_c);

        }
        const t *ptrs = values; cimg_for(*this,ptrd,T) *ptrd = (T)*(ptrs++);
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer \specialization.
    CImg(const T *const values, const unsigned int size_x, const unsigned int size_y=1,
         const unsigned int size_z=1, const unsigned int size_c=1, const bool is_shared=false) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (values && siz) {
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c; _is_shared = is_shared;
        if (_is_shared) _data = const_cast<T*>(values);
        else {
          try { _data = new T[siz]; } catch (...) {
            _width = _height = _depth = _spectrum = 0; _data = 0;
            throw CImgInstanceException(_cimg_instance
                                        "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                        cimg_instance,
                                        cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                        size_x,size_y,size_z,size_c);
          }
          std::memcpy(_data,values,siz*sizeof(T));
        }
      } else { _width = _height = _depth = _spectrum = 0; _is_shared = false; _data = 0; }
    }

    //! Construct image from memory buffer with specified size and pixel ordering scheme.
    template<typename t>
    CImg(const t *const values, const unsigned int size_x, const unsigned int size_y,
         const unsigned int size_z, const unsigned int size_c,
         const char *const axes_order):_data(0),_is_shared(false) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (values && siz) {
        unsigned char s_code[4] = { 0,1,2,3 }, n_code[4] = {};
        for (unsigned int l = 0; axes_order[l]; ++l) {
          int c = cimg::lowercase(axes_order[l]);
          if (l>=4 || (c!='x' && c!='y' && c!='z' && c!='c')) { *s_code = 4; break; }
          else { ++n_code[c%=4]; s_code[l] = c; }
        }
        if (*axes_order && *s_code<4 && *n_code<=1 && n_code[1]<=1 && n_code[2]<=1 && n_code[3]<=1) {
          const unsigned int code = (s_code[0]<<12) | (s_code[1]<<8) | (s_code[2]<<4) | (s_code[3]);
          int s0 = 0, s1 = 0, s2 = 0, s3 = 0;
          const char *inv_order = 0;
          switch (code) {
            case 0x0123 : inv_order = "xyzc"; s0 = size_x; s1 = size_y; s2 = size_z; s3 = size_c; break; // xyzc
            case 0x0132 : inv_order = "xyzc"; s0 = size_x; s1 = size_y; s2 = size_c; s3 = size_z; break; // xycz
            case 0x0213 : inv_order = "xzyc"; s0 = size_x; s1 = size_z; s2 = size_y; s3 = size_c; break; // xzyc
            case 0x0231 : inv_order = "xcyz"; s0 = size_x; s1 = size_z; s2 = size_c; s3 = size_y; break; // xzcy
            case 0x0312 : inv_order = "xzcy"; s0 = size_x; s1 = size_c; s2 = size_y; s3 = size_z; break; // xcyz
            case 0x0321 : inv_order = "xczy"; s0 = size_x; s1 = size_c; s2 = size_z; s3 = size_y; break; // xczy
            case 0x1023 : inv_order = "yxzc"; s0 = size_y; s1 = size_x; s2 = size_z; s3 = size_c; break; // yxzc
            case 0x1032 : inv_order = "yxcz"; s0 = size_y; s1 = size_x; s2 = size_c; s3 = size_z; break; // yxcz
            case 0x1203 : inv_order = "zxyc"; s0 = size_y; s1 = size_z; s2 = size_x; s3 = size_c; break; // yzxc
            case 0x1230 : inv_order = "cxyz"; s0 = size_y; s1 = size_z; s2 = size_c; s3 = size_x; break; // yzcx
            case 0x1302 : inv_order = "zxcy"; s0 = size_y; s1 = size_c; s2 = size_x; s3 = size_z; break; // ycxz
            case 0x1320 : inv_order = "cxzy"; s0 = size_y; s1 = size_c; s2 = size_z; s3 = size_x; break; // yczx
            case 0x2013 : inv_order = "yzxc"; s0 = size_z; s1 = size_x; s2 = size_y; s3 = size_c; break; // zxyc
            case 0x2031 : inv_order = "ycxz"; s0 = size_z; s1 = size_x; s2 = size_c; s3 = size_y; break; // zxcy
            case 0x2103 : inv_order = "zyxc"; s0 = size_z; s1 = size_y; s2 = size_x; s3 = size_c; break; // zyxc
            case 0x2130 : inv_order = "cyxz"; s0 = size_z; s1 = size_y; s2 = size_c; s3 = size_x; break; // zycx
            case 0x2301 : inv_order = "zcxy"; s0 = size_z; s1 = size_c; s2 = size_x; s3 = size_y; break; // zcxy
            case 0x2310 : inv_order = "czxy"; s0 = size_z; s1 = size_c; s2 = size_y; s3 = size_x; break; // zcyx
            case 0x3012 : inv_order = "yzcx"; s0 = size_c; s1 = size_x; s2 = size_y; s3 = size_z; break; // cxyz
            case 0x3021 : inv_order = "yczx"; s0 = size_c; s1 = size_x; s2 = size_z; s3 = size_y; break; // cxzy
            case 0x3102 : inv_order = "zycx"; s0 = size_c; s1 = size_y; s2 = size_x; s3 = size_z; break; // cyxz
            case 0x3120 : inv_order = "cyzx"; s0 = size_c; s1 = size_y; s2 = size_z; s3 = size_x; break; // cyzx
            case 0x3201 : inv_order = "zcyx"; s0 = size_c; s1 = size_z; s2 = size_x; s3 = size_y; break; // czxy
            case 0x3210 : inv_order = "czyx"; s0 = size_c; s1 = size_z; s2 = size_y; s3 = size_x; break; // czyx
          }
          CImg<t>(values,s0,s1,s2,s3,true).get_permute_axes(inv_order).move_to(*this);
        } else {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgArgumentException(_cimg_instance
                                      "CImg(): Invalid specified axes order '%s'.",
                                      cimg_instance,
                                      axes_order);
        }
      } else { _width = _height = _depth = _spectrum = 0; _is_shared = false; _data = 0; }
    }

    //! Construct image from reading an image file.
    /**
       Construct a new image instance with pixels of type \c T, and initialize pixel values with the data read from
       an image file.
       \param filename Filename, as a C-string.
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int), but it reads the image
         dimensions and pixel values from the specified image file.
       - The recognition of the image file format by \CImg higlhy depends on the tools installed on your system
         and on the external libraries you used to link your code against.
       - Considered pixel type \c T should better fit the file format specification, or data loss may occur during
         file load (e.g. constructing a \c CImg<unsigned char> from a float-valued image file).
       - A \c CImgIOException is thrown when the specified \c filename cannot be read, or if the file format is not
         recognized.
       \par Example
       \code
       const CImg<float> img("reference.jpg");
       img.display();
       \endcode
       \image html ref_image.jpg
    **/
    explicit CImg(const char *const filename):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(filename);
    }

    //! Construct image copy.
    /**
       Construct a new image instance with pixels of type \c T, as a copy of an existing \c CImg<t> instance.
       \param img Input image to copy.
       \note
       - Constructed copy has the same size width() x height() x depth() x spectrum() and pixel values as the
         input image \c img.
       - If input image \c img is \e shared and if types \c T and \c t are the same, the constructed copy is also
         \e shared, and shares its pixel buffer with \c img.
         Modifying a pixel value in the constructed copy will thus also modifies it in the input image \c img.
         This behavior is needful to allow functions to return shared images.
       - Otherwise, the constructed copy allocates its own pixel buffer, and copies pixel values from the input
         image \c img into its buffer. The copied pixel values may be eventually statically casted if types \c T and
         \c t are different.
       - Constructing a copy from an image \c img when types \c t and \c T are the same is significantly faster than
         with different types.
       - A \c CImgInstanceException is thrown when the pixel buffer cannot be allocated
         (e.g. not enough available memory).
    **/
    template<typename t>
    CImg(const CImg<t>& img):_is_shared(false) {
      const size_t siz = (size_t)img.size();
      if (img._data && siz) {
        _width = img._width; _height = img._height; _depth = img._depth; _spectrum = img._spectrum;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*img._width*img._height*img._depth*img._spectrum),
                                      img._width,img._height,img._depth,img._spectrum);
        }
        const t *ptrs = img._data; cimg_for(*this,ptrd,T) *ptrd = (T)*(ptrs++);
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Construct image copy \specialization.
    CImg(const CImg<T>& img) {
      const size_t siz = (size_t)img.size();
      if (img._data && siz) {
        _width = img._width; _height = img._height; _depth = img._depth; _spectrum = img._spectrum;
        _is_shared = img._is_shared;
        if (_is_shared) _data = const_cast<T*>(img._data);
        else {
          try { _data = new T[siz]; } catch (...) {
            _width = _height = _depth = _spectrum = 0; _data = 0;
            throw CImgInstanceException(_cimg_instance
                                        "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                        cimg_instance,
                                        cimg::strbuffersize(sizeof(T)*img._width*img._height*img._depth*img._spectrum),
                                        img._width,img._height,img._depth,img._spectrum);

          }
          std::memcpy(_data,img._data,siz*sizeof(T));
        }
      } else { _width = _height = _depth = _spectrum = 0; _is_shared = false; _data = 0; }
    }

    //! Advanced copy constructor.
    /**
       Construct a new image instance with pixels of type \c T, as a copy of an existing \c CImg<t> instance,
       while forcing the shared state of the constructed copy.
       \param img Input image to copy.
       \param is_shared Indicates the shared state of the constructed copy.
       \note
       - Similar to CImg(const CImg<t>&), except that it allows users to decide the shared state of
         the constructed image, which does not depend anymore on the shared state of the input image \c img:
         - If \c is_shared is \c true, the constructed copy will share its pixel buffer with the input image \c img.
           For that case, the pixel types \c T and \c t \e must be the same.
         - If \c is_shared is \c false, the constructed copy will allocate its own pixel buffer, whether the input
           image \c img is shared or not.
       - A \c CImgArgumentException is thrown when a shared copy is requested with different pixel types \c T and \c t.
    **/
    template<typename t>
    CImg(const CImg<t>& img, const bool is_shared):_is_shared(false) {
      if (is_shared) {
        _width = _height = _depth = _spectrum = 0; _data = 0;
        throw CImgArgumentException(_cimg_instance
                                    "CImg(): Invalid request for constructing a shared instance from a "
                                    "CImg<%s> image (%u,%u,%u,%u,%p) (pixel types are different).",
                                    cimg_instance,
                                    CImg<t>::pixel_type(),img._width,img._height,img._depth,img._spectrum,img._data);
      }
      const size_t siz = (size_t)img.size();
      if (img._data && siz) {
        _width = img._width; _height = img._height; _depth = img._depth; _spectrum = img._spectrum;
        try { _data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*img._width*img._height*img._depth*img._spectrum),
                                      img._width,img._height,img._depth,img._spectrum);
        }
        const t *ptrs = img._data; cimg_for(*this,ptrd,T) *ptrd = (T)*(ptrs++);
      } else { _width = _height = _depth = _spectrum = 0; _data = 0; }
    }

    //! Advanced copy constructor \specialization.
    CImg(const CImg<T>& img, const bool is_shared) {
      const size_t siz = (size_t)img.size();
      if (img._data && siz) {
        _width = img._width; _height = img._height; _depth = img._depth; _spectrum = img._spectrum;
        _is_shared = is_shared;
        if (_is_shared) _data = const_cast<T*>(img._data);
        else {
          try { _data = new T[siz]; } catch (...) {
            _width = _height = _depth = _spectrum = 0; _data = 0;
            throw CImgInstanceException(_cimg_instance
                                        "CImg(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                        cimg_instance,
                                        cimg::strbuffersize(sizeof(T)*img._width*img._height*img._depth*img._spectrum),
                                        img._width,img._height,img._depth,img._spectrum);
          }
          std::memcpy(_data,img._data,siz*sizeof(T));
        }
      } else { _width = _height = _depth = _spectrum = 0; _is_shared = false; _data = 0; }
    }

    //! Construct image with dimensions borrowed from another image.
    /**
       Construct a new image instance with pixels of type \c T, and size get from some dimensions of an existing
       \c CImg<t> instance.
       \param img Input image from which dimensions are borrowed.
       \param dimensions C-string describing the image size along the X,Y,Z and C-dimensions.
       \note
       - Similar to CImg(unsigned int,unsigned int,unsigned int,unsigned int), but it takes the image dimensions
         (\e not its pixel values) from an existing \c CImg<t> instance.
       - The allocated pixel buffer is \e not filled with a default value, and is likely to contain garbage values.
         In order to initialize pixel values (e.g. with \c 0), use constructor CImg(const CImg<t>&,const char*,T)
         instead.
       \par Example
       \code
       const CImg<float> img1(256,128,1,3), // 'img1' is a 256x128x1x3 image
                         img2(img1,"xyzc"), // 'img2' is a 256x128x1x3 image
                         img3(img1,"y,x,z,c"), // 'img3' is a 128x256x1x3 image
                         img4(img1,"c,x,y,3",0), // 'img4' is a 3x128x256x3 image (with pixels initialized to '0')
       \endcode
     **/
    template<typename t>
    CImg(const CImg<t>& img, const char *const dimensions):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(img,dimensions);
    }

    //! Construct image with dimensions borrowed from another image and initialize pixel values.
    /**
       Construct a new image instance with pixels of type \c T, and size get from the dimensions of an existing
       \c CImg<t> instance, and set all pixel values to specified \c value.
       \param img Input image from which dimensions are borrowed.
       \param dimensions String describing the image size along the X,Y,Z and V-dimensions.
       \param value Value used for initialization.
       \note
       - Similar to CImg(const CImg<t>&,const char*), but it also fills the pixel buffer with the specified \c value.
     **/
    template<typename t>
    CImg(const CImg<t>& img, const char *const dimensions, const T& value):
      _width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      assign(img,dimensions).fill(value);
    }

    //! Construct image from a display window.
    /**
       Construct a new image instance with pixels of type \c T, as a snapshot of an existing \c CImgDisplay instance.
       \param disp Input display window.
       \note
       - The width() and height() of the constructed image instance are the same as the specified \c CImgDisplay.
       - The depth() and spectrum() of the constructed image instance are respectively set to \c 1 and \c 3
         (i.e. a 2D color image).
       - The image pixels are read as 8-bits RGB values.
     **/
    explicit CImg(const CImgDisplay &disp):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      disp.snapshot(*this);
    }

    // Constructor and assignment operator for rvalue references (c++11).
    // This avoids an additional image copy for functions returning new images. Can save RAM for big images!
#if cimg_use_cpp11==1
    CImg(CImg<T>&& img):_width(0),_height(0),_depth(0),_spectrum(0),_is_shared(false),_data(0) {
      swap(img);
    }

    CImg<T>& operator=(CImg<T>&& img) {
      if (_is_shared) return assign(img);
      return img.swap(*this);
    }
#endif

    //! Construct empty image \inplace.
    /**
       In-place version of the default constructor CImg(). It simply resets the instance to an empty image.
    **/
    CImg<T>& assign() {
      if (!_is_shared) delete[] _data;
      _width = _height = _depth = _spectrum = 0; _is_shared = false; _data = 0;
      return *this;
    }

    //! Construct image with specified size \inplace.
    /**
       In-place version of the constructor CImg(unsigned int,unsigned int,unsigned int,unsigned int).
    **/
    CImg<T>& assign(const unsigned int size_x, const unsigned int size_y=1,
                    const unsigned int size_z=1, const unsigned int size_c=1) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (!siz) return assign();
      const size_t curr_siz = (size_t)size();
      if (siz!=curr_siz) {
        if (_is_shared)
          throw CImgArgumentException(_cimg_instance
                                      "assign(): Invalid request for assigning a shared instance from specified "
                                      "image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      size_x,size_y,size_z,size_c);
        if (siz>curr_siz || (curr_siz>4096 && siz<curr_siz/2)) {
          delete[] _data;
          try { _data = new T[siz]; } catch (...) {
            _width = _height = _depth = _spectrum = 0; _data = 0;
            throw CImgInstanceException(_cimg_instance
                                        "assign(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                        cimg_instance,
                                        cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                        size_x,size_y,size_z,size_c);
          }
        }
      }
      _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
      return *this;
    }

    //! Construct image with specified size and initialize pixel values \inplace.
    /**
       In-place version of the constructor CImg(unsigned int,unsigned int,unsigned int,unsigned int,T).
    **/
    CImg<T>& assign(const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c, const T& value) {
      return assign(size_x,size_y,size_z,size_c).fill(value);
    }

    //! Construct image with specified size and initialize pixel values from a sequence of integers \inplace.
    /**
       In-place version of the constructor CImg(unsigned int,unsigned int,unsigned int,unsigned int,int,int,...).
    **/
    CImg<T>& assign(const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c,
                    const int value0, const int value1, ...) {
      assign(size_x,size_y,size_z,size_c);
      _CImg_stdarg(*this,value0,value1,safe_size(size_x,size_y,size_z,size_c),int);
      return *this;
    }

    //! Construct image with specified size and initialize pixel values from a sequence of doubles \inplace.
    /**
       In-place version of the constructor CImg(unsigned int,unsigned int,unsigned int,unsigned int,double,double,...).
    **/
    CImg<T>& assign(const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c,
                    const double value0, const double value1, ...) {
      assign(size_x,size_y,size_z,size_c);
      _CImg_stdarg(*this,value0,value1,safe_size(size_x,size_y,size_z,size_c),double);
      return *this;
    }

    //! Construct image with specified size and initialize pixel values from a value string \inplace.
    /**
       In-place version of the constructor CImg(unsigned int,unsigned int,unsigned int,unsigned int,const char*,bool).
    **/
    CImg<T>& assign(const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c,
                    const char *const values, const bool repeat_values) {
      return assign(size_x,size_y,size_z,size_c).fill(values,repeat_values);
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer \inplace.
    /**
       In-place version of the constructor CImg(const t*,unsigned int,unsigned int,unsigned int,unsigned int).
    **/
    template<typename t>
    CImg<T>& assign(const t *const values, const unsigned int size_x, const unsigned int size_y=1,
                    const unsigned int size_z=1, const unsigned int size_c=1) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (!values || !siz) return assign();
      assign(size_x,size_y,size_z,size_c);
      const t *ptrs = values; cimg_for(*this,ptrd,T) *ptrd = (T)*(ptrs++);
      return *this;
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer \specialization.
    CImg<T>& assign(const T *const values, const unsigned int size_x, const unsigned int size_y=1,
                    const unsigned int size_z=1, const unsigned int size_c=1) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (!values || !siz) return assign();
      const size_t curr_siz = (size_t)size();
      if (values==_data && siz==curr_siz) return assign(size_x,size_y,size_z,size_c);
      if (_is_shared || values + siz<_data || values>=_data + size()) {
        assign(size_x,size_y,size_z,size_c);
        if (_is_shared) std::memmove((void*)_data,(void*)values,siz*sizeof(T));
        else std::memcpy((void*)_data,(void*)values,siz*sizeof(T));
      } else {
        T *new_data = 0;
        try { new_data = new T[siz]; } catch (...) {
          _width = _height = _depth = _spectrum = 0; _data = 0;
          throw CImgInstanceException(_cimg_instance
                                      "assign(): Failed to allocate memory (%s) for image (%u,%u,%u,%u).",
                                      cimg_instance,
                                      cimg::strbuffersize(sizeof(T)*size_x*size_y*size_z*size_c),
                                      size_x,size_y,size_z,size_c);
        }
        std::memcpy((void*)new_data,(void*)values,siz*sizeof(T));
        delete[] _data; _data = new_data; _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c;
      }
      return *this;
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer \overload.
    template<typename t>
    CImg<T>& assign(const t *const values, const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c, const bool is_shared) {
      if (is_shared)
        throw CImgArgumentException(_cimg_instance
                                    "assign(): Invalid request for assigning a shared instance from (%s*) buffer "
                                    "(pixel types are different).",
                                    cimg_instance,
                                    CImg<t>::pixel_type());
      return assign(values,size_x,size_y,size_z,size_c);
    }

    //! Construct image with specified size and initialize pixel values from a memory buffer \overload.
    CImg<T>& assign(const T *const values, const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c, const bool is_shared) {
      const size_t siz = safe_size(size_x,size_y,size_z,size_c);
      if (!values || !siz) return assign();
      if (!is_shared) { if (_is_shared) assign(); assign(values,size_x,size_y,size_z,size_c); }
      else {
        if (!_is_shared) {
          if (values + siz<_data || values>=_data + size()) assign();
          else cimg::warn(_cimg_instance
                          "assign(): Shared image instance has overlapping memory.",
                          cimg_instance);
        }
        _width = size_x; _height = size_y; _depth = size_z; _spectrum = size_c; _is_shared = true;
        _data = const_cast<T*>(values);
      }
      return *this;
    }

    //! Construct image from memory buffer with specified size and pixel ordering scheme.
    template<typename t>
    CImg<T>& assign(const t *const values, const unsigned int size_x, const unsigned int size_y,
                    const unsigned int size_z, const unsigned int size_c,
                    const char *const axes_order) {
      CImg<T>(values,size_x,size_y,size_z,size_c,axes_order).move_to(*this);
    }

    //! Construct image from reading an image file \inplace.
    /**
       In-place version of the constructor CImg(const char*).
    **/
    CImg<T>& assign(const char *const filename) {
      return load(filename);
    }

    //! Construct image copy \inplace.
    /**
       In-place version of the constructor CImg(const CImg<t>&).
    **/
    template<typename t>
    CImg<T>& assign(const CImg<t>& img) {
      return assign(img._data,img._width,img._height,img._depth,img._spectrum);
    }

    //! In-place version of the advanced copy constructor.
    /**
       In-place version of the constructor CImg(const CImg<t>&,bool).
     **/
    template<typename t>
    CImg<T>& assign(const CImg<t>& img, const bool is_shared) {
      return assign(img._data,img._width,img._height,img._depth,img._spectrum,is_shared);
    }

    //! Construct image from a display window \inplace.
    /**
       In-place version of the constructor CImg(const CImgDisplay&).
    **/
    CImg<T>& assign(const CImgDisplay &disp) {
      disp.snapshot(*this);
      return *this;
    }

    //! Construct empty image \inplace.
    /**
       Equivalent to assign().
       \note
       - It has been defined for compatibility with STL naming conventions.
    **/
    CImg<T>& clear() {
      return assign();
    }

    //! Transfer content of an image instance into another one.
    /**
       Transfers the dimensions and the pixel buffer content of an image instance into another one,
       and replace instance by an empty image. It avoids the copy of the pixel buffer
       when possible.
       \param img Destination image.
       \note
       - Pixel types \c T and \c t of source and destination images can be different, though the process is
         designed to be instantaneous when \c T and \c t are the same.
       \par Example
       \code
       CImg<float> src(256,256,1,3,0), // Construct a 256x256x1x3 (color) image filled with value '0'
                   dest(16,16); // Construct a 16x16x1x1 (scalar) image
       src.move_to(dest); // Now, 'src' is empty and 'dest' is the 256x256x1x3 image
       \endcode
    **/
    template<typename t>
    CImg<t>& move_to(CImg<t>& img) {
      img.assign(*this);
      assign();
      return img;
    }

    //! Transfer content of an image instance into another one \specialization.
    CImg<T>& move_to(CImg<T>& img) {
      if (_is_shared || img._is_shared) img.assign(*this);
      else swap(img);
      assign();
      return img;
    }

    //! Transfer content of an image instance into a new image in an image list.
    /**
       Transfers the dimensions and the pixel buffer content of an image instance
       into a newly inserted image at position \c pos in specified \c CImgList<t> instance.
       \param list Destination list.
       \param pos Position of the newly inserted image in the list.
       \note
       - When optional parameter \c pos is omitted, the image instance is transferred as a new
         image at the end of the specified \c list.
       - It is convenient to sequentially insert new images into image lists, with no
         additional copies of memory buffer.
       \par Example
       \code
       CImgList<float> list; // Construct an empty image list
       CImg<float> img("reference.jpg"); // Read image from filename
       img.move_to(list); // Transfer image content as a new item in the list (no buffer copy)
       \endcode
    **/
    template<typename t>
    CImgList<t>& move_to(CImgList<t>& list, const unsigned int pos=~0U) {
      const unsigned int npos = pos>list._width?list._width:pos;
      move_to(list.insert(1,npos)[npos]);
      return list;
    }

    //! Swap fields of two image instances.
    /**
      \param img Image to swap fields with.
      \note
      - It can be used to interchange the content of two images in a very fast way. Can be convenient when dealing
        with algorithms requiring two swapping buffers.
      \par Example
      \code
      CImg<float> img1("lena.jpg"),
                  img2("milla.jpg");
      img1.swap(img2); // Now, 'img1' is 'milla' and 'img2' is 'lena'
      \endcode
    **/
    CImg<T>& swap(CImg<T>& img) {
      cimg::swap(_width,img._width,_height,img._height,_depth,img._depth,_spectrum,img._spectrum);
      cimg::swap(_data,img._data);
      cimg::swap(_is_shared,img._is_shared);
      return img;
    }

    //! Return a reference to an empty image.
    /**
       \note
       This function is useful mainly to declare optional parameters having type \c CImg<T> in functions prototypes,
       e.g.
       \code
       void f(const int x=0, const int y=0, const CImg<float>& img=CImg<float>::empty());
       \endcode
     **/
    static CImg<T>& empty() {
      static CImg<T> _empty;
      return _empty.assign();
    }

    //! Return a reference to an empty image \const.
    static const CImg<T>& const_empty() {
      static const CImg<T> _empty;
      return _empty;
    }

    //@}
    //------------------------------------------
    //
    //! \name Overloaded Operators
    //@{
    //------------------------------------------

    //! Access to a pixel value.
    /**
       Return a reference to a located pixel value of the image instance,
       being possibly \e const, whether the image instance is \e const or not.
       This is the standard function to get/set pixel values in \c CImg<T> images.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Range of pixel coordinates start from <tt>(0,0,0,0)</tt> to
         <tt>(width() - 1,height() - 1,depth() - 1,spectrum() - 1)</tt>.
       - Due to the particular arrangement of the pixel buffers defined in \CImg, you can omit one coordinate if the
         corresponding dimension is equal to \c 1.
         For instance, pixels of a 2D image (depth() equal to \c 1) can be accessed by <tt>img(x,y,c)</tt> instead of
         <tt>img(x,y,0,c)</tt>.
       \warning
       - There is \e no boundary checking done in this operator, to make it as fast as possible.
         You \e must take care of out-of-bounds access by yourself, if necessary.
         For debugging purposes, you may want to define macro \c 'cimg_verbosity'>=3 to enable additional boundary
         checking operations in this operator. In that case, warning messages will be printed on the error output
         when accessing out-of-bounds pixels.
       \par Example
       \code
       CImg<float> img(100,100,1,3,0); // Construct a 100x100x1x3 (color) image with pixels set to '0'
       const float
          valR = img(10,10,0,0), // Read red value at coordinates (10,10)
          valG = img(10,10,0,1), // Read green value at coordinates (10,10)
          valB = img(10,10,2), // Read blue value at coordinates (10,10) (Z-coordinate can be omitted)
          avg = (valR + valG + valB)/3; // Compute average pixel value
       img(10,10,0) = img(10,10,1) = img(10,10,2) = avg; // Replace the color pixel (10,10) by the average grey value
       \endcode
    **/
#if cimg_verbosity>=3
    T& operator()(const unsigned int x, const unsigned int y=0,
                  const unsigned int z=0, const unsigned int c=0) {
      const ulongT off = (ulongT)offset(x,y,z,c);
      if (!_data || off>=size()) {
        cimg::warn(_cimg_instance
                   "operator(): Invalid pixel request, at coordinates (%d,%d,%d,%d) [offset=%u].",
                   cimg_instance,
                   (int)x,(int)y,(int)z,(int)c,off);
        return *_data;
      }
      else return _data[off];
    }

    //! Access to a pixel value \const.
    const T& operator()(const unsigned int x, const unsigned int y=0,
                        const unsigned int z=0, const unsigned int c=0) const {
      return const_cast<CImg<T>*>(this)->operator()(x,y,z,c);
    }

    //! Access to a pixel value.
    /**
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param wh Precomputed offset, must be equal to <tt>width()*\ref height()</tt>.
       \param whd Precomputed offset, must be equal to <tt>width()*\ref height()*\ref depth()</tt>.
       \note
       - Similar to (but faster than) operator()().
         It uses precomputed offsets to optimize memory access. You may use it to optimize
         the reading/writing of several pixel values in the same image (e.g. in a loop).
     **/
    T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c,
                  const ulongT wh, const ulongT whd=0) {
      cimg::unused(wh,whd);
      return (*this)(x,y,z,c);
    }

    //! Access to a pixel value \const.
    const T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c,
                        const ulongT wh, const ulongT whd=0) const {
      cimg::unused(wh,whd);
      return (*this)(x,y,z,c);
    }
#else
    T& operator()(const unsigned int x) {
      return _data[x];
    }

    const T& operator()(const unsigned int x) const {
      return _data[x];
    }

    T& operator()(const unsigned int x, const unsigned int y) {
      return _data[x + y*_width];
    }

    const T& operator()(const unsigned int x, const unsigned int y) const {
      return _data[x + y*_width];
    }

    T& operator()(const unsigned int x, const unsigned int y, const unsigned int z) {
      return _data[x + y*(ulongT)_width + z*(ulongT)_width*_height];
   }

    const T& operator()(const unsigned int x, const unsigned int y, const unsigned int z) const {
      return _data[x + y*(ulongT)_width + z*(ulongT)_width*_height];
    }

    T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c) {
      return _data[x + y*(ulongT)_width + z*(ulongT)_width*_height + c*(ulongT)_width*_height*_depth];
    }

    const T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c) const {
      return _data[x + y*(ulongT)_width + z*(ulongT)_width*_height + c*(ulongT)_width*_height*_depth];
    }

    T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int,
                  const ulongT wh) {
      return _data[x + y*_width + z*wh];
    }

    const T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int,
                        const ulongT wh) const {
      return _data[x + y*_width + z*wh];
    }

    T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c,
                  const ulongT wh, const ulongT whd) {
      return _data[x + y*_width + z*wh + c*whd];
    }

    const T& operator()(const unsigned int x, const unsigned int y, const unsigned int z, const unsigned int c,
                        const ulongT wh, const ulongT whd) const {
      return _data[x + y*_width + z*wh + c*whd];
    }
#endif

    //! Implicitly cast an image into a \c T*.
    /**
       Implicitly cast a \c CImg<T> instance into a \c T* or \c const \c T* pointer, whether the image instance
       is \e const or not. The returned pointer points on the first value of the image pixel buffer.
       \note
       - It simply returns the pointer data() to the pixel buffer.
       - This implicit conversion is convenient to test the empty state of images (data() being \c 0 in this case), e.g.
       \code
       CImg<float> img1(100,100), img2; // 'img1' is a 100x100 image, 'img2' is an empty image
       if (img1) { // Test succeeds, 'img1' is not an empty image
         if (!img2) { // Test succeeds, 'img2' is an empty image
           std::printf("'img1' is not empty, 'img2' is empty.");
         }
       }
       \endcode
       - It also allows users to use brackets to access pixel values, without need for a \c CImg<T>::operator[](), e.g.
       \code
       CImg<float> img(100,100);
       const float value = img[99]; // Access to value of the last pixel on the first row
       img[510] = 255; // Set pixel value at (10,5)
       \endcode
    **/
    operator T*() {
      return _data;
    }

    //! Implicitly cast an image into a \c T* \const.
    operator const T*() const {
      return _data;
    }

    //! Assign a value to all image pixels.
    /**
       Assign specified \c value to each pixel value of the image instance.
       \param value Value that will be assigned to image pixels.
       \note
       - The image size is never modified.
       - The \c value may be casted to pixel type \c T if necessary.
       \par Example
       \code
       CImg<char> img(100,100); // Declare image (with garbage values)
       img = 0; // Set all pixel values to '0'
       img = 1.2; // Set all pixel values to '1' (cast of '1.2' as a 'char')
       \endcode
    **/
    CImg<T>& operator=(const T& value) {
      return fill(value);
    }

    //! Assign pixels values from a specified expression.
    /**
       Initialize all pixel values from the specified string \c expression.
       \param expression Value string describing the way pixel values are set.
       \note
       - String parameter \c expression may describe different things:
         - If \c expression is a list of values (as in \c "1,2,3,8,3,2"), or a formula (as in \c "(x*y)%255"),
           the pixel values are set from specified \c expression and the image size is not modified.
         - If \c expression is a filename (as in \c "reference.jpg"), the corresponding image file is loaded and
           replace the image instance. The image size is modified if necessary.
       \par Example
       \code
       CImg<float> img1(100,100), img2(img1), img3(img1); // Declare 3 scalar images 100x100 with uninitialized values
       img1 = "0,50,100,150,200,250,200,150,100,50"; // Set pixel values of 'img1' from a value sequence
       img2 = "10*((x*y)%25)"; // Set pixel values of 'img2' from a formula
       img3 = "reference.jpg"; // Set pixel values of 'img3' from a file (image size is modified)
       (img1,img2,img3).display();
       \endcode
       \image html ref_operator_eq.jpg
    **/
    CImg<T>& operator=(const char *const expression) {
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      try {
        _fill(expression,true,3,(CImgList<T>*)0,"operator=",(CImg<T>*)0,(CImg<doubleT>*)0);
      } catch (CImgException&) {
        cimg::exception_mode(omode);
        load(expression);
      }
      cimg::exception_mode(omode);
      return *this;
    }

    //! Copy an image into the current image instance.
    /**
       Similar to the in-place copy constructor assign(const CImg<t>&).
    **/
    template<typename t>
    CImg<T>& operator=(const CImg<t>& img) {
      return assign(img);
    }

    //! Copy an image into the current image instance \specialization.
    CImg<T>& operator=(const CImg<T>& img) {
      return assign(img);
    }

    //! Copy the content of a display window to the current image instance.
    /**
       Similar to assign(const CImgDisplay&).
    **/
    CImg<T>& operator=(const CImgDisplay& disp) {
      disp.snapshot(*this);
      return *this;
    }

    //! In-place addition operator.
    /**
       Add specified \c value to all pixels of an image instance.
       \param value Value to add.
       \note
       - Resulting pixel values are casted to fit the pixel type \c T.
         For instance, adding \c 0.2 to a \c CImg<char> is possible but does nothing indeed.
       - Overflow values are treated as with standard C++ numeric types. For instance,
       \code
       CImg<unsigned char> img(100,100,1,1,255); // Construct a 100x100 image with pixel values '255'
       img+=1; // Add '1' to each pixels -> Overflow
       // here all pixels of image 'img' are equal to '0'.
       \endcode
       - To prevent value overflow, you may want to consider pixel type \c T as \c float or \c double,
         and use cut() after addition.
       \par Example
       \code
       CImg<unsigned char> img1("reference.jpg"); // Load a 8-bits RGB image (values in [0,255])
       CImg<float> img2(img1); // Construct a float-valued copy of 'img1'
       img2+=100; // Add '100' to pixel values -> goes out of [0,255] but no problems with floats
       img2.cut(0,255); // Cut values in [0,255] to fit the 'unsigned char' constraint
       img1 = img2; // Rewrite safe result in 'unsigned char' version 'img1'
       const CImg<unsigned char> img3 = (img1 + 100).cut(0,255); // Do the same in a more simple and elegant way
       (img1,img2,img3).display();
       \endcode
       \image html ref_operator_plus.jpg
     **/
    template<typename t>
    CImg<T>& operator+=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr + value,524288,T);
      return *this;
    }

    //! In-place addition operator.
    /**
       Add values to image pixels, according to the specified string \c expression.
       \param expression Value string describing the way pixel values are added.
       \note
       - Similar to operator=(const char*), except that it adds values to the pixels of the current image instance,
         instead of assigning them.
    **/
    CImg<T>& operator+=(const char *const expression) {
      return *this+=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator+=",this,(CImg<doubleT>*)0);
    }

    //! In-place addition operator.
    /**
       Add values to image pixels, according to the values of the input image \c img.
       \param img Input image to add.
       \note
       - The size of the image instance is never modified.
       - It is not mandatory that input image \c img has the same size as the image instance.
         If fewer values are available in \c img, then the values are added periodically. For instance, adding one
         WxH scalar image (spectrum() equal to \c 1) to one WxH color image (spectrum() equal to \c 3)
         means each color channel will be incremented with the same values at the same locations.
       \par Example
       \code
       CImg<float> img1("reference.jpg"); // Load a RGB color image (img1.spectrum()==3)
       // Construct a scalar shading (img2.spectrum()==1).
       const CImg<float> img2(img1.width(),img.height(),1,1,"255*(x/w)^2");
       img1+=img2; // Add shading to each channel of 'img1'
       img1.cut(0,255); // Prevent [0,255] overflow
       (img2,img1).display();
       \endcode
       \image html ref_operator_plus1.jpg
    **/
    template<typename t>
    CImg<T>& operator+=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this+=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)(*ptrd + *(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)(*ptrd + *(ptrs++));
      }
      return *this;
    }

    //! In-place increment operator (prefix).
    /**
       Add \c 1 to all image pixels, and return a reference to the current incremented image instance.
       \note
       - Writing \c ++img is equivalent to \c img+=1.
     **/
    CImg<T>& operator++() {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr + 1,524288,T);
      return *this;
    }

    //! In-place increment operator (postfix).
    /**
       Add \c 1 to all image pixels, and return a new copy of the initial (pre-incremented) image instance.
       \note
       - Use the prefixed version operator++() if you don't need a copy of the initial
         (pre-incremented) image instance, since a useless image copy may be expensive in terms of memory usage.
     **/
    CImg<T> operator++(int) {
      const CImg<T> copy(*this,false);
      ++*this;
      return copy;
    }

    //! Return a non-shared copy of the image instance.
    /**
       \note
       - Use this operator to ensure you get a non-shared copy of an image instance with same pixel type \c T.
         Indeed, the usual copy constructor CImg<T>(const CImg<T>&) returns a shared copy of a shared input image,
         and it may be not desirable to work on a regular copy (e.g. for a resize operation) if you have no
         information about the shared state of the input image.
       - Writing \c (+img) is equivalent to \c CImg<T>(img,false).
    **/
    CImg<T> operator+() const {
      return CImg<T>(*this,false);
    }

    //! Addition operator.
    /**
       Similar to operator+=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
     **/
    template<typename t>
    CImg<_cimg_Tt> operator+(const t value) const {
      return CImg<_cimg_Tt>(*this,false)+=value;
    }

    //! Addition operator.
    /**
       Similar to operator+=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
     **/
    CImg<Tfloat> operator+(const char *const expression) const {
      return CImg<Tfloat>(*this,false)+=expression;
    }

    //! Addition operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
     **/
    template<typename t>
    CImg<_cimg_Tt> operator+(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false)+=img;
    }

    //! In-place subtraction operator.
    /**
       Similar to operator+=(const t), except that it performs a subtraction instead of an addition.
     **/
    template<typename t>
    CImg<T>& operator-=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr - value,524288,T);
      return *this;
    }

    //! In-place subtraction operator.
    /**
       Similar to operator+=(const char*), except that it performs a subtraction instead of an addition.
     **/
    CImg<T>& operator-=(const char *const expression) {
      return *this-=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator-=",this,(CImg<doubleT>*)0);
    }

    //! In-place subtraction operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a subtraction instead of an addition.
     **/
    template<typename t>
    CImg<T>& operator-=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this-=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)(*ptrd - *(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)(*ptrd - *(ptrs++));
      }
      return *this;
    }

    //! In-place decrement operator (prefix).
    /**
       Similar to operator++(), except that it performs a decrement instead of an increment.
    **/
    CImg<T>& operator--() {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr - 1,524288,T);
      return *this;
    }

    //! In-place decrement operator (postfix).
    /**
       Similar to operator++(int), except that it performs a decrement instead of an increment.
    **/
    CImg<T> operator--(int) {
      const CImg<T> copy(*this,false);
      --*this;
      return copy;
    }

    //! Replace each pixel by its opposite value.
    /**
       \note
       - If the computed opposite values are out-of-range, they are treated as with standard C++ numeric types.
         For instance, the \c unsigned \c char opposite of \c 1 is \c 255.
       \par Example
       \code
       const CImg<unsigned char>
         img1("reference.jpg"), // Load a RGB color image
         img2 = -img1; // Compute its opposite (in 'unsigned char')
       (img1,img2).display();
       \endcode
       \image html ref_operator_minus.jpg
     **/
    CImg<T> operator-() const {
      return CImg<T>(_width,_height,_depth,_spectrum,(T)0)-=*this;
    }

    //! Subtraction operator.
    /**
       Similar to operator-=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator-(const t value) const {
      return CImg<_cimg_Tt>(*this,false)-=value;
    }

    //! Subtraction operator.
    /**
       Similar to operator-=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    CImg<Tfloat> operator-(const char *const expression) const {
      return CImg<Tfloat>(*this,false)-=expression;
    }

    //! Subtraction operator.
    /**
       Similar to operator-=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator-(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false)-=img;
    }

    //! In-place multiplication operator.
    /**
       Similar to operator+=(const t), except that it performs a multiplication instead of an addition.
     **/
    template<typename t>
    CImg<T>& operator*=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr * value,262144,T);
      return *this;
    }

    //! In-place multiplication operator.
    /**
       Similar to operator+=(const char*), except that it performs a multiplication instead of an addition.
     **/
    CImg<T>& operator*=(const char *const expression) {
      return mul((+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator*=",this,(CImg<doubleT>*)0));
    }

    //! In-place multiplication operator.
    /**
       Replace the image instance by the matrix multiplication between the image instance and the specified matrix
       \c img.
       \param img Second operand of the matrix multiplication.
       \note
       - It does \e not compute a pointwise multiplication between two images. For this purpose, use
         mul(const CImg<t>&) instead.
       - The size of the image instance can be modified by this operator.
       \par Example
       \code
       CImg<float> A(2,2,1,1, 1,2,3,4); // Construct 2x2 matrix A = [1,2;3,4]
       const CImg<float> X(1,2,1,1, 1,2); // Construct 1x2 vector X = [1;2]
       A*=X; // Assign matrix multiplication A*X to 'A'
       // 'A' is now a 1x2 vector whose values are [5;11].
       \endcode
    **/
    template<typename t>
    CImg<T>& operator*=(const CImg<t>& img) {
      return ((*this)*img).move_to(*this);
    }

    //! Multiplication operator.
    /**
       Similar to operator*=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator*(const t value) const {
      return CImg<_cimg_Tt>(*this,false)*=value;
    }

    //! Multiplication operator.
    /**
       Similar to operator*=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    CImg<Tfloat> operator*(const char *const expression) const {
      return CImg<Tfloat>(*this,false)*=expression;
    }

    //! Multiplication operator.
    /**
       Similar to operator*=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator*(const CImg<t>& img) const {
      typedef _cimg_Ttdouble Ttdouble;
      typedef _cimg_Tt Tt;
      if (_width!=img._height || _depth!=1 || _spectrum!=1 || img._depth!=1 || img._spectrum!=1)
        throw CImgArgumentException(_cimg_instance
                                    "operator*(): Invalid multiplication of instance by specified "
                                    "matrix (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    img._width,img._height,img._depth,img._spectrum,img._data);
      CImg<Tt> res(img._width,_height);

      // Check for common cases to optimize.
      if (img._width==1) { // Matrix * Vector
        if (_height==1) switch (_width) { // Vector^T * Vector
          case 1 :
            res[0] = (Tt)((Ttdouble)_data[0]*img[0]);
            return res;
          case 2 :
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1]);
            return res;
          case 3 :
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1] +
                          (Ttdouble)_data[2]*img[2]);
            return res;
          case 4 :
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1] +
                          (Ttdouble)_data[2]*img[2] + (Ttdouble)_data[3]*img[3]);
            return res;
          default : {
            Ttdouble val = 0;
            cimg_pragma_openmp(parallel for reduction(+:val) cimg_openmp_if_size(size(),4096))
            cimg_forX(*this,i) val+=(Ttdouble)_data[i]*img[i];
            res[0] = val;
            return res;
          }
          } else if (_height==_width) switch (_width) { // Square_matrix * Vector
          case 2 : // 2x2_matrix * Vector
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1]);
            res[1] = (Tt)((Ttdouble)_data[2]*img[0] + (Ttdouble)_data[3]*img[1]);
            return res;
          case 3 : // 3x3_matrix * Vector
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1] +
                          (Ttdouble)_data[2]*img[2]);
            res[1] = (Tt)((Ttdouble)_data[3]*img[0] + (Ttdouble)_data[4]*img[1] +
                          (Ttdouble)_data[5]*img[2]);
            res[2] = (Tt)((Ttdouble)_data[6]*img[0] + (Ttdouble)_data[7]*img[1] +
                          (Ttdouble)_data[8]*img[2]);
            return res;
          case 4 : // 4x4_matrix * Vector
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[1] +
                          (Ttdouble)_data[2]*img[2] + (Ttdouble)_data[3]*img[3]);
            res[1] = (Tt)((Ttdouble)_data[4]*img[0] + (Ttdouble)_data[5]*img[1] +
                          (Ttdouble)_data[6]*img[2] + (Ttdouble)_data[7]*img[3]);
            res[2] = (Tt)((Ttdouble)_data[8]*img[0] + (Ttdouble)_data[9]*img[1] +
                          (Ttdouble)_data[10]*img[2] + (Ttdouble)_data[11]*img[3]);
            res[3] = (Tt)((Ttdouble)_data[12]*img[0] + (Ttdouble)_data[13]*img[1] +
                          (Ttdouble)_data[14]*img[2] + (Ttdouble)_data[15]*img[3]);
            return res;
          }
      } else if (_height==_width) {
        if (img._height==img._width) switch (_width) { // Square_matrix * Square_matrix
          case 2 : // 2x2_matrix * 2x2_matrix
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[2]);
            res[1] = (Tt)((Ttdouble)_data[0]*img[1] + (Ttdouble)_data[1]*img[3]);
            res[2] = (Tt)((Ttdouble)_data[2]*img[0] + (Ttdouble)_data[3]*img[2]);
            res[3] = (Tt)((Ttdouble)_data[2]*img[1] + (Ttdouble)_data[3]*img[3]);
            return res;
          case 3 : // 3x3_matrix * 3x3_matrix
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[3] +
                          (Ttdouble)_data[2]*img[6]);
            res[1] = (Tt)((Ttdouble)_data[0]*img[1] + (Ttdouble)_data[1]*img[4] +
                          (Ttdouble)_data[2]*img[7]);
            res[2] = (Tt)((Ttdouble)_data[0]*img[2] + (Ttdouble)_data[1]*img[5] +
                          (Ttdouble)_data[2]*img[8]);
            res[3] = (Tt)((Ttdouble)_data[3]*img[0] + (Ttdouble)_data[4]*img[3] +
                          (Ttdouble)_data[5]*img[6]);
            res[4] = (Tt)((Ttdouble)_data[3]*img[1] + (Ttdouble)_data[4]*img[4] +
                          (Ttdouble)_data[5]*img[7]);
            res[5] = (Tt)((Ttdouble)_data[3]*img[2] + (Ttdouble)_data[4]*img[5] +
                          (Ttdouble)_data[5]*img[8]);
            res[6] = (Tt)((Ttdouble)_data[6]*img[0] + (Ttdouble)_data[7]*img[3] +
                          (Ttdouble)_data[8]*img[6]);
            res[7] = (Tt)((Ttdouble)_data[6]*img[1] + (Ttdouble)_data[7]*img[4] +
                          (Ttdouble)_data[8]*img[7]);
            res[8] = (Tt)((Ttdouble)_data[6]*img[2] + (Ttdouble)_data[7]*img[5] +
                          (Ttdouble)_data[8]*img[8]);
            return res;
          case 4 : // 4x4_matrix * 4x4_matrix
            res[0] = (Tt)((Ttdouble)_data[0]*img[0] + (Ttdouble)_data[1]*img[4] +
                          (Ttdouble)_data[2]*img[8] + (Ttdouble)_data[3]*img[12]);
            res[1] = (Tt)((Ttdouble)_data[0]*img[1] + (Ttdouble)_data[1]*img[5] +
                          (Ttdouble)_data[2]*img[9] + (Ttdouble)_data[3]*img[13]);
            res[2] = (Tt)((Ttdouble)_data[0]*img[2] + (Ttdouble)_data[1]*img[6] +
                          (Ttdouble)_data[2]*img[10] + (Ttdouble)_data[3]*img[14]);
            res[3] = (Tt)((Ttdouble)_data[0]*img[3] + (Ttdouble)_data[1]*img[7] +
                          (Ttdouble)_data[2]*img[11] + (Ttdouble)_data[3]*img[15]);
            res[4] = (Tt)((Ttdouble)_data[4]*img[0] + (Ttdouble)_data[5]*img[4] +
                          (Ttdouble)_data[6]*img[8] + (Ttdouble)_data[7]*img[12]);
            res[5] = (Tt)((Ttdouble)_data[4]*img[1] + (Ttdouble)_data[5]*img[5] +
                          (Ttdouble)_data[6]*img[9] + (Ttdouble)_data[7]*img[13]);
            res[6] = (Tt)((Ttdouble)_data[4]*img[2] + (Ttdouble)_data[5]*img[6] +
                          (Ttdouble)_data[6]*img[10] + (Ttdouble)_data[7]*img[14]);
            res[7] = (Tt)((Ttdouble)_data[4]*img[3] + (Ttdouble)_data[5]*img[7] +
                          (Ttdouble)_data[6]*img[11] + (Ttdouble)_data[7]*img[15]);
            res[8] = (Tt)((Ttdouble)_data[8]*img[0] + (Ttdouble)_data[9]*img[4] +
                          (Ttdouble)_data[10]*img[8] + (Ttdouble)_data[11]*img[12]);
            res[9] = (Tt)((Ttdouble)_data[8]*img[1] + (Ttdouble)_data[9]*img[5] +
                          (Ttdouble)_data[10]*img[9] + (Ttdouble)_data[11]*img[13]);
            res[10] = (Tt)((Ttdouble)_data[8]*img[2] + (Ttdouble)_data[9]*img[6] +
                           (Ttdouble)_data[10]*img[10] + (Ttdouble)_data[11]*img[14]);
            res[11] = (Tt)((Ttdouble)_data[8]*img[3] + (Ttdouble)_data[9]*img[7] +
                           (Ttdouble)_data[10]*img[11] + (Ttdouble)_data[11]*img[15]);
            res[12] = (Tt)((Ttdouble)_data[12]*img[0] + (Ttdouble)_data[13]*img[4] +
                           (Ttdouble)_data[14]*img[8] + (Ttdouble)_data[15]*img[12]);
            res[13] = (Tt)((Ttdouble)_data[12]*img[1] + (Ttdouble)_data[13]*img[5] +
                           (Ttdouble)_data[14]*img[9] + (Ttdouble)_data[15]*img[13]);
            res[14] = (Tt)((Ttdouble)_data[12]*img[2] + (Ttdouble)_data[13]*img[6] +
                           (Ttdouble)_data[14]*img[10] + (Ttdouble)_data[15]*img[14]);
            res[15] = (Tt)((Ttdouble)_data[12]*img[3] + (Ttdouble)_data[13]*img[7] +
                           (Ttdouble)_data[14]*img[11] + (Ttdouble)_data[15]*img[15]);
            return res;
          } else switch (_width) { // Square_matrix * Matrix
          case 2 : { // 2x2_matrix * Matrix
            const t *const ps0 = img.data(), *const ps1 = img.data(0,1);
            Tt *const pd0 = res.data(), *const pd1 = res.data(0,1);
            const Ttdouble
              a0 = (Ttdouble)_data[0], a1 = (Ttdouble)_data[1],
              a2 = (Ttdouble)_data[2], a3 = (Ttdouble)_data[3];
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(img.width(),4096))
            cimg_forX(img,i) {
              const Ttdouble x = (Ttdouble)ps0[i], y = (Ttdouble)ps1[i];
              pd0[i] = (Tt)(a0*x + a1*y);
              pd1[i] = (Tt)(a2*x + a3*y);
            }
            return res;
          }
          case 3 : { // 3x3_matrix * Matrix
            const t *const ps0 = img.data(), *const ps1 = img.data(0,1), *const ps2 = img.data(0,2);
            Tt *const pd0 = res.data(), *const pd1 = res.data(0,1), *const pd2 = res.data(0,2);
            const Ttdouble
              a0 = (Ttdouble)_data[0], a1 = (Ttdouble)_data[1], a2 = (Ttdouble)_data[2],
              a3 = (Ttdouble)_data[3], a4 = (Ttdouble)_data[4], a5 = (Ttdouble)_data[5],
              a6 = (Ttdouble)_data[6], a7 = (Ttdouble)_data[7], a8 = (Ttdouble)_data[8];
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(img.width(),1024))
            cimg_forX(img,i) {
              const Ttdouble x = (Ttdouble)ps0[i], y = (Ttdouble)ps1[i], z = (Ttdouble)ps2[i];
              pd0[i] = (Tt)(a0*x + a1*y + a2*z);
              pd1[i] = (Tt)(a3*x + a4*y + a5*z);
              pd2[i] = (Tt)(a6*x + a7*y + a8*z);
            }
            return res;
          }
          case 4 : { // 4x4_matrix * Matrix
            const t
              *const ps0 = img.data(), *const ps1 = img.data(0,1),
              *const ps2 = img.data(0,2), *const ps3 = img.data(0,3);
            Tt
              *const pd0 = res.data(), *const pd1 = res.data(0,1),
              *const pd2 = res.data(0,2), *const pd3 = res.data(0,3);
            const Ttdouble
              a0 = (Ttdouble)_data[0], a1 = (Ttdouble)_data[1], a2 = (Ttdouble)_data[2], a3 = (Ttdouble)_data[3],
              a4 = (Ttdouble)_data[4], a5 = (Ttdouble)_data[5], a6 = (Ttdouble)_data[6], a7 = (Ttdouble)_data[7],
              a8 = (Ttdouble)_data[8], a9 = (Ttdouble)_data[9], a10 = (Ttdouble)_data[10], a11 = (Ttdouble)_data[11],
              a12 = (Ttdouble)_data[12], a13 = (Ttdouble)_data[13], a14 = (Ttdouble)_data[14],
              a15 = (Ttdouble)_data[15];
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(img.width(),512))
            cimg_forX(img,i) {
              const Ttdouble x = (Ttdouble)ps0[i], y = (Ttdouble)ps1[i], z = (Ttdouble)ps2[i], c = (Ttdouble)ps3[i];
              pd0[i] = (Tt)(a0*x + a1*y + a2*z + a3*c);
              pd1[i] = (Tt)(a4*x + a5*y + a6*z + a7*c);
              pd2[i] = (Tt)(a8*x + a9*y + a10*z + a11*c);
              pd3[i] = (Tt)(a12*x + a13*y + a14*z + a15*c);
            }
            return res;
          }
          }
      }

      // Fallback to generic version.
#if cimg_use_openmp!=0
      cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                         cimg_openmp_if(size()>(cimg_openmp_sizefactor)*1024 &&
                                        img.size()>(cimg_openmp_sizefactor)*1024))
      cimg_forXY(res,i,j) {
        Ttdouble value = 0;
        cimg_forX(*this,k) value+=(*this)(k,j)*img(i,k);
        res(i,j) = (Tt)value;
      }
#else
      Tt *ptrd = res._data;
      cimg_forXY(res,i,j) {
        Ttdouble value = 0;
        cimg_forX(*this,k) value+=(*this)(k,j)*img(i,k);
        *(ptrd++) = (Tt)value;
      }
#endif
      return res;
    }

    //! In-place division operator.
    /**
       Similar to operator+=(const t), except that it performs a division instead of an addition.
     **/
    template<typename t>
    CImg<T>& operator/=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,*ptr / value,32768,T);
      return *this;
    }

    //! In-place division operator.
    /**
       Similar to operator+=(const char*), except that it performs a division instead of an addition.
     **/
    CImg<T>& operator/=(const char *const expression) {
      return div((+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator/=",this,(CImg<doubleT>*)0));
    }

    //! In-place division operator.
    /**
       Replace the image instance by the (right) matrix division between the image instance and the specified
       matrix \c img.
       \param img Second operand of the matrix division.
       \note
       - It does \e not compute a pointwise division between two images. For this purpose, use
         div(const CImg<t>&) instead.
       - It returns the matrix operation \c A*inverse(img).
       - The size of the image instance can be modified by this operator.
     **/
    template<typename t>
    CImg<T>& operator/=(const CImg<t>& img) {
      return (*this*img.get_invert()).move_to(*this);
    }

    //! Division operator.
    /**
       Similar to operator/=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator/(const t value) const {
      return CImg<_cimg_Tt>(*this,false)/=value;
    }

    //! Division operator.
    /**
       Similar to operator/=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    CImg<Tfloat> operator/(const char *const expression) const {
      return CImg<Tfloat>(*this,false)/=expression;
    }

    //! Division operator.
    /**
       Similar to operator/=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator/(const CImg<t>& img) const {
      return (*this)*img.get_invert();
    }

    //! In-place modulo operator.
    /**
       Similar to operator+=(const t), except that it performs a modulo operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator%=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,cimg::mod(*ptr,(T)value),16384,T);
      return *this;
    }

    //! In-place modulo operator.
    /**
       Similar to operator+=(const char*), except that it performs a modulo operation instead of an addition.
    **/
    CImg<T>& operator%=(const char *const expression) {
      return *this%=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator%=",this,(CImg<doubleT>*)0);
    }

    //! In-place modulo operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a modulo operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator%=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this%=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = cimg::mod(*ptrd,(T)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = cimg::mod(*ptrd,(T)*(ptrs++));
      }
      return *this;
    }

    //! Modulo operator.
    /**
       Similar to operator%=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator%(const t value) const {
      return CImg<_cimg_Tt>(*this,false)%=value;
    }

    //! Modulo operator.
    /**
       Similar to operator%=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    CImg<Tfloat> operator%(const char *const expression) const {
      return CImg<Tfloat>(*this,false)%=expression;
    }

    //! Modulo operator.
    /**
       Similar to operator%=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image may be a superset of the initial pixel type \c T, if necessary.
    **/
    template<typename t>
    CImg<_cimg_Tt> operator%(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false)%=img;
    }

    //! In-place bitwise AND operator.
    /**
       Similar to operator+=(const t), except that it performs a bitwise AND operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator&=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,(longT)*ptr & (longT)value,32768,T);
      return *this;
    }

    //! In-place bitwise AND operator.
    /**
       Similar to operator+=(const char*), except that it performs a bitwise AND operation instead of an addition.
    **/
    CImg<T>& operator&=(const char *const expression) {
      return *this&=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator&=",this,(CImg<doubleT>*)0);
    }

    //! In-place bitwise AND operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a bitwise AND operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator&=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this&=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)((longT)*ptrd & (longT)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)((longT)*ptrd & (longT)*(ptrs++));
      }
      return *this;
    }

    //! Bitwise AND operator.
    /**
       Similar to operator&=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator&(const t value) const {
      return (+*this)&=value;
    }

    //! Bitwise AND operator.
    /**
       Similar to operator&=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    CImg<T> operator&(const char *const expression) const {
      return (+*this)&=expression;
    }

    //! Bitwise AND operator.
    /**
       Similar to operator&=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator&(const CImg<t>& img) const {
      return (+*this)&=img;
    }

    //! In-place bitwise OR operator.
    /**
       Similar to operator+=(const t), except that it performs a bitwise OR operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator|=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,(longT)*ptr | (longT)value,32768,T);
      return *this;
    }

    //! In-place bitwise OR operator.
    /**
       Similar to operator+=(const char*), except that it performs a bitwise OR operation instead of an addition.
    **/
    CImg<T>& operator|=(const char *const expression) {
      return *this|=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator|=",this,(CImg<doubleT>*)0);
    }

    //! In-place bitwise OR operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a bitwise OR operation instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator|=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this|=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)((longT)*ptrd | (longT)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)((longT)*ptrd | (longT)*(ptrs++));
      }
      return *this;
    }

    //! Bitwise OR operator.
    /**
       Similar to operator|=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator|(const t value) const {
      return (+*this)|=value;
    }

    //! Bitwise OR operator.
    /**
       Similar to operator|=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    CImg<T> operator|(const char *const expression) const {
      return (+*this)|=expression;
    }

    //! Bitwise OR operator.
    /**
       Similar to operator|=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator|(const CImg<t>& img) const {
      return (+*this)|=img;
    }

    //! In-place bitwise XOR operator.
    /**
       Similar to operator+=(const t), except that it performs a bitwise XOR operation instead of an addition.
       \warning
       - It does \e not compute the \e power of pixel values. For this purpose, use pow(const t) instead.
    **/
    template<typename t>
    CImg<T>& operator^=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,(longT)*ptr ^ (longT)value,32768,T);
      return *this;
    }

    //! In-place bitwise XOR operator.
    /**
       Similar to operator+=(const char*), except that it performs a bitwise XOR operation instead of an addition.
       \warning
       - It does \e not compute the \e power of pixel values. For this purpose, use pow(const char*) instead.
    **/
    CImg<T>& operator^=(const char *const expression) {
      return *this^=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator^=",this,(CImg<doubleT>*)0);
    }

    //! In-place bitwise XOR operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a bitwise XOR operation instead of an addition.
       \warning
       - It does \e not compute the \e power of pixel values. For this purpose, use pow(const CImg<t>&) instead.
    **/
    template<typename t>
    CImg<T>& operator^=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this^=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)((longT)*ptrd ^ (longT)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)((longT)*ptrd ^ (longT)*(ptrs++));
      }
      return *this;
    }

    //! Bitwise XOR operator.
    /**
       Similar to operator^=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator^(const t value) const {
      return (+*this)^=value;
    }

    //! Bitwise XOR operator.
    /**
       Similar to operator^=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    CImg<T> operator^(const char *const expression) const {
      return (+*this)^=expression;
    }

    //! Bitwise XOR operator.
    /**
       Similar to operator^=(const CImg<t>&), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator^(const CImg<t>& img) const {
      return (+*this)^=img;
    }

    //! In-place bitwise left shift operator.
    /**
       Similar to operator+=(const t), except that it performs a bitwise left shift instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator<<=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,((longT)*ptr) << (int)value,65536,T);
      return *this;
    }

    //! In-place bitwise left shift operator.
    /**
       Similar to operator+=(const char*), except that it performs a bitwise left shift instead of an addition.
    **/
    CImg<T>& operator<<=(const char *const expression) {
      return *this<<=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator<<=",this,(CImg<doubleT>*)0);
    }

    //! In-place bitwise left shift operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a bitwise left shift instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator<<=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this^=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)((longT)*ptrd << (int)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)((longT)*ptrd << (int)*(ptrs++));
      }
      return *this;
    }

    //! Bitwise left shift operator.
    /**
       Similar to operator<<=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator<<(const t value) const {
      return (+*this)<<=value;
    }

    //! Bitwise left shift operator.
    /**
       Similar to operator<<=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    CImg<T> operator<<(const char *const expression) const {
      return (+*this)<<=expression;
    }

    //! Bitwise left shift operator.
    /**
       Similar to operator<<=(const CImg<t>&), except that it returns a new image instance instead of
       operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator<<(const CImg<t>& img) const {
      return (+*this)<<=img;
    }

    //! In-place bitwise right shift operator.
    /**
       Similar to operator+=(const t), except that it performs a bitwise right shift instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator>>=(const t value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,((longT)*ptr) >> (int)value,65536,T);
      return *this;
    }

    //! In-place bitwise right shift operator.
    /**
       Similar to operator+=(const char*), except that it performs a bitwise right shift instead of an addition.
    **/
    CImg<T>& operator>>=(const char *const expression) {
      return *this>>=(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator>>=",this,(CImg<doubleT>*)0);
    }

    //! In-place bitwise right shift operator.
    /**
       Similar to operator+=(const CImg<t>&), except that it performs a bitwise right shift instead of an addition.
    **/
    template<typename t>
    CImg<T>& operator>>=(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return *this^=+img;
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)((longT)*ptrd >> (int)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)((longT)*ptrd >> (int)*(ptrs++));
      }
      return *this;
    }

    //! Bitwise right shift operator.
    /**
       Similar to operator>>=(const t), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator>>(const t value) const {
      return (+*this)>>=value;
    }

    //! Bitwise right shift operator.
    /**
       Similar to operator>>=(const char*), except that it returns a new image instance instead of operating in-place.
       The pixel type of the returned image is \c T.
    **/
    CImg<T> operator>>(const char *const expression) const {
      return (+*this)>>=expression;
    }

    //! Bitwise right shift operator.
    /**
       Similar to operator>>=(const CImg<t>&), except that it returns a new image instance instead of
       operating in-place.
       The pixel type of the returned image is \c T.
    **/
    template<typename t>
    CImg<T> operator>>(const CImg<t>& img) const {
      return (+*this)>>=img;
    }

    //! Bitwise inversion operator.
    /**
       Similar to operator-(), except that it compute the bitwise inverse instead of the opposite value.
    **/
    CImg<T> operator~() const {
      CImg<T> res(_width,_height,_depth,_spectrum);
      const T *ptrs = _data;
      cimg_for(res,ptrd,T) { const ulongT value = (ulongT)*(ptrs++); *ptrd = (T)~value; }
      return res;
    }

    //! Test if all pixels of an image have the same value.
    /**
       Return \c true is all pixels of the image instance are equal to the specified \c value.
       \param value Reference value to compare with.
    **/
    template<typename t>
    bool operator==(const t value) const {
      if (is_empty()) return false;
      typedef _cimg_Tt Tt;
      bool is_equal = true;
      for (T *ptrd = _data + size(); is_equal && ptrd>_data; is_equal = ((Tt)*(--ptrd)==(Tt)value)) {}
      return is_equal;
    }

    //! Test if all pixel values of an image follow a specified expression.
    /**
       Return \c true is all pixels of the image instance are equal to the specified \c expression.
       \param expression Value string describing the way pixel values are compared.
    **/
    bool operator==(const char *const expression) const {
      return *this==(+*this)._fill(expression,true,3,(CImgList<T>*)0,"operator==",this,(CImg<doubleT>*)0);
    }

    //! Test if two images have the same size and values.
    /**
       Return \c true if the image instance and the input image \c img have the same pixel values,
       even if the dimensions of the two images do not match. It returns \c false otherwise.
       \param img Input image to compare with.
       \note
       - The pixel buffer pointers data() of the two compared images do not have to be the same for operator==()
         to return \c true.
         Only the dimensions and the pixel values matter. Thus, the comparison can be \c true even for different
         pixel types \c T and \c t.
       \par Example
       \code
       const CImg<float> img1(1,3,1,1, 0,1,2); // Construct a 1x3 vector [0;1;2] (with 'float' pixel values)
       const CImg<char> img2(1,3,1,1, 0,1,2); // Construct a 1x3 vector [0;1;2] (with 'char' pixel values)
       if (img1==img2) { // Test succeeds, image dimensions and values are the same
         std::printf("'img1' and 'img2' have same dimensions and values.");
       }
       \endcode
    **/
    template<typename t>
    bool operator==(const CImg<t>& img) const {
      typedef _cimg_Tt Tt;
      const ulongT siz = size();
      bool is_equal = true;
      if (siz!=img.size()) return false;
      t *ptrs = img._data + siz;
      for (T *ptrd = _data + siz; is_equal && ptrd>_data; is_equal = ((Tt)*(--ptrd)==(Tt)*(--ptrs))) {}
      return is_equal;
    }

    //! Test if pixels of an image are all different from a value.
    /**
       Return \c true is all pixels of the image instance are different than the specified \c value.
       \param value Reference value to compare with.
    **/
    template<typename t>
    bool operator!=(const t value) const {
      return !((*this)==value);
    }

    //! Test if all pixel values of an image are different from a specified expression.
    /**
       Return \c true is all pixels of the image instance are different to the specified \c expression.
       \param expression Value string describing the way pixel values are compared.
    **/
    bool operator!=(const char *const expression) const {
      return !((*this)==expression);
    }

    //! Test if two images have different sizes or values.
    /**
       Return \c true if the image instance and the input image \c img have different dimensions or pixel values,
       and \c false otherwise.
       \param img Input image to compare with.
       \note
       - Writing \c img1!=img2 is equivalent to \c !(img1==img2).
    **/
    template<typename t>
    bool operator!=(const CImg<t>& img) const {
      return !((*this)==img);
    }

    //! Construct an image list from two images.
    /**
       Return a new list of image (\c CImgList instance) containing exactly two elements:
         - A copy of the image instance, at position [\c 0].
         - A copy of the specified image \c img, at position [\c 1].

       \param img Input image that will be the second image of the resulting list.
       \note
       - The family of operator,() is convenient to easily create list of images, but it is also \e quite \e slow
         in practice (see warning below).
       - Constructed lists contain no shared images. If image instance or input image \c img are shared, they are
         inserted as new non-shared copies in the resulting list.
       - The pixel type of the returned list may be a superset of the initial pixel type \c T, if necessary.
       \warning
       - Pipelining operator,() \c N times will perform \c N copies of the entire content of a (growing) image list.
         This may become very expensive in terms of speed and used memory. You should avoid using this technique to
         build a new CImgList instance from several images, if you are seeking for performance.
         Fast insertions of images in an image list are possible with
         CImgList<T>::insert(const CImg<t>&,unsigned int,bool) or move_to(CImgList<t>&,unsigned int).
       \par Example
       \code
       const CImg<float>
          img1("reference.jpg"),
          img2 = img1.get_mirror('x'),
          img3 = img2.get_blur(5);
       const CImgList<float> list = (img1,img2); // Create list of two elements from 'img1' and 'img2'
       (list,img3).display(); // Display image list containing copies of 'img1','img2' and 'img3'
       \endcode
       \image html ref_operator_comma.jpg
    **/
    template<typename t>
    CImgList<_cimg_Tt> operator,(const CImg<t>& img) const {
      return CImgList<_cimg_Tt>(*this,img);
    }

    //! Construct an image list from image instance and an input image list.
    /**
       Return a new list of images (\c CImgList instance) containing exactly \c list.size() \c + \c 1 elements:
         - A copy of the image instance, at position [\c 0].
         - A copy of the specified image list \c list, from positions [\c 1] to [\c list.size()].

       \param list Input image list that will be appended to the image instance.
       \note
       - Similar to operator,(const CImg<t>&) const, except that it takes an image list as an argument.
    **/
    template<typename t>
    CImgList<_cimg_Tt> operator,(const CImgList<t>& list) const {
      return CImgList<_cimg_Tt>(list,false).insert(*this,0);
    }

    //! Split the image along a specified axis.
    /**
       Return a new list of images (\c CImgList instance) containing the split components
       of the instance image along the specified axis.
       \param axis Splitting axis (can be '\c x','\c y','\c z' or '\c c')
       \note
       - Similar to get_split(char,int) const, with default second argument.
       \par Example
       \code
       const CImg<unsigned char> img("reference.jpg"); // Load a RGB color image
       const CImgList<unsigned char> list = (img<'c'); // Get a list of its three R,G,B channels
       (img,list).display();
       \endcode
       \image html ref_operator_less.jpg
    **/
    CImgList<T> operator<(const char axis) const {
      return get_split(axis);
    }

    //@}
    //-------------------------------------
    //
    //! \name Instance Characteristics
    //@{
    //-------------------------------------

    //! Return the type of image pixel values as a C string.
    /**
       Return a \c char* string containing the usual type name of the image pixel values
       (i.e. a stringified version of the template parameter \c T).
       \note
       - The returned string does not contain any spaces.
       - If the pixel type \c T does not correspond to a registered type, the string <tt>"unknown"</tt> is returned.
    **/
    static const char* pixel_type() {
      return cimg::type<T>::string();
    }

    //! Return the number of image columns.
    /**
       Return the image width, i.e. the image dimension along the X-axis.
       \note
       - The width() of an empty image is equal to \c 0.
       - width() is typically equal to \c 1 when considering images as \e vectors for matrix calculations.
       - width() returns an \c int, although the image width is internally stored as an \c unsigned \c int.
         Using an \c int is safer and prevents arithmetic traps possibly encountered when doing calculations involving
         \c unsigned \c int variables.
         Access to the initial \c unsigned \c int variable is possible (though not recommended) by
         <tt>(*this)._width</tt>.
    **/
    int width() const {
      return (int)_width;
    }

    //! Return the number of image rows.
    /**
       Return the image height, i.e. the image dimension along the Y-axis.
       \note
       - The height() of an empty image is equal to \c 0.
       - height() returns an \c int, although the image height is internally stored as an \c unsigned \c int.
         Using an \c int is safer and prevents arithmetic traps possibly encountered when doing calculations involving
         \c unsigned \c int variables.
         Access to the initial \c unsigned \c int variable is possible (though not recommended) by
         <tt>(*this)._height</tt>.
    **/
    int height() const {
      return (int)_height;
    }

    //! Return the number of image slices.
    /**
       Return the image depth, i.e. the image dimension along the Z-axis.
       \note
       - The depth() of an empty image is equal to \c 0.
       - depth() is typically equal to \c 1 when considering usual 2D images. When depth()\c > \c 1, the image
         is said to be \e volumetric.
       - depth() returns an \c int, although the image depth is internally stored as an \c unsigned \c int.
         Using an \c int is safer and prevents arithmetic traps possibly encountered when doing calculations involving
         \c unsigned \c int variables.
         Access to the initial \c unsigned \c int variable is possible (though not recommended) by
         <tt>(*this)._depth</tt>.
    **/
    int depth() const {
      return (int)_depth;
    }

    //! Return the number of image channels.
    /**
       Return the number of image channels, i.e. the image dimension along the C-axis.
       \note
       - The spectrum() of an empty image is equal to \c 0.
       - spectrum() is typically equal to \c 1 when considering scalar-valued images, to \c 3
         for RGB-coded color images, and to \c 4 for RGBA-coded color images (with alpha-channel).
         The number of channels of an image instance is not limited. The meaning of the pixel values is not linked
         up to the number of channels (e.g. a 4-channel image may represent either a RGBA or a CMYK color image).
       - spectrum() returns an \c int, although the image spectrum is internally stored as an \c unsigned \c int.
         Using an \c int is safer and prevents arithmetic traps possibly encountered when doing calculations involving
         \c unsigned \c int variables.
         Access to the initial \c unsigned \c int variable is possible (though not recommended) by
         <tt>(*this)._spectrum</tt>.
    **/
    int spectrum() const {
      return (int)_spectrum;
    }

    //! Return the total number of pixel values.
    /**
       Return <tt>width()*\ref height()*\ref depth()*\ref spectrum()</tt>,
       i.e. the total number of values of type \c T in the pixel buffer of the image instance.
       \note
       - The size() of an empty image is equal to \c 0.
       - The allocated memory size for a pixel buffer of a non-shared \c CImg<T> instance is equal to
         <tt>size()*sizeof(T)</tt>.
       \par Example
       \code
       const CImg<float> img(100,100,1,3); // Construct new 100x100 color image
       if (img.size()==30000) // Test succeeds
         std::printf("Pixel buffer uses %lu bytes",
                     img.size()*sizeof(float));
       \endcode
    **/
    ulongT size() const {
      return (ulongT)_width*_height*_depth*_spectrum;
    }

    //! Return a pointer to the first pixel value.
    /**
       Return a \c T*, or a \c const \c T* pointer to the first value in the pixel buffer of the image instance,
       whether the instance is \c const or not.
       \note
       - The data() of an empty image is equal to \c 0 (null pointer).
       - The allocated pixel buffer for the image instance starts from \c data()
         and goes to <tt>data()+\ref size() - 1</tt> (included).
       - To get the pointer to one particular location of the pixel buffer, use
         data(unsigned int,unsigned int,unsigned int,unsigned int) instead.
    **/
    T* data() {
      return _data;
    }

    //! Return a pointer to the first pixel value \const.
    const T* data() const {
      return _data;
    }

    //! Return a pointer to a located pixel value.
    /**
       Return a \c T*, or a \c const \c T* pointer to the value located at (\c x,\c y,\c z,\c c) in the pixel buffer
       of the image instance, whether the instance is \c const or not.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Writing \c img.data(x,y,z,c) is equivalent to <tt>&(img(x,y,z,c))</tt>. Thus, this function has the same
         properties as operator()(unsigned int,unsigned int,unsigned int,unsigned int).
     **/
#if cimg_verbosity>=3
    T *data(const unsigned int x, const unsigned int y=0, const unsigned int z=0, const unsigned int c=0) {
      const ulongT off = (ulongT)offset(x,y,z,c);
      if (off>=size())
        cimg::warn(_cimg_instance
                   "data(): Invalid pointer request, at coordinates (%u,%u,%u,%u) [offset=%u].",
                   cimg_instance,
                   x,y,z,c,off);
      return _data + off;
    }

    //! Return a pointer to a located pixel value \const.
    const T* data(const unsigned int x, const unsigned int y=0, const unsigned int z=0, const unsigned int c=0) const {
      return const_cast<CImg<T>*>(this)->data(x,y,z,c);
    }
#else
    T* data(const unsigned int x, const unsigned int y=0, const unsigned int z=0, const unsigned int c=0) {
      return _data + x + (ulongT)y*_width + (ulongT)z*_width*_height + (ulongT)c*_width*_height*_depth;
    }

    const T* data(const unsigned int x, const unsigned int y=0, const unsigned int z=0, const unsigned int c=0) const {
      return _data + x + (ulongT)y*_width + (ulongT)z*_width*_height + (ulongT)c*_width*_height*_depth;
    }
#endif

    //! Return the offset to a located pixel value, with respect to the beginning of the pixel buffer.
    /**
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Writing \c img.data(x,y,z,c) is equivalent to <tt>&(img(x,y,z,c)) - img.data()</tt>.
         Thus, this function has the same properties as operator()(unsigned int,unsigned int,unsigned int,unsigned int).
       \par Example
       \code
       const CImg<float> img(100,100,1,3); // Define a 100x100 RGB-color image
       const long off = img.offset(10,10,0,2); // Get the offset of the blue value of the pixel located at (10,10)
       const float val = img[off]; // Get the blue value of this pixel
       \endcode
    **/
    longT offset(const int x, const int y=0, const int z=0, const int c=0) const {
      return x + (longT)y*_width + (longT)z*_width*_height + (longT)c*_width*_height*_depth;
    }

    //! Return a CImg<T>::iterator pointing to the first pixel value.
    /**
       \note
       - Equivalent to data().
       - It has been mainly defined for compatibility with STL naming conventions.
     **/
    iterator begin() {
      return _data;
    }

    //! Return a CImg<T>::iterator pointing to the first value of the pixel buffer \const.
    const_iterator begin() const {
      return _data;
    }

    //! Return a CImg<T>::iterator pointing next to the last pixel value.
    /**
       \note
       - Writing \c img.end() is equivalent to <tt>img.data() + img.size()</tt>.
       - It has been mainly defined for compatibility with STL naming conventions.
       \warning
       - The returned iterator actually points to a value located \e outside the acceptable bounds of the pixel buffer.
         Trying to read or write the content of the returned iterator will probably result in a crash.
         Use it mainly as a strict upper bound for a CImg<T>::iterator.
       \par Example
       \code
       CImg<float> img(100,100,1,3); // Define a 100x100 RGB color image
       // 'img.end()' used below as an upper bound for the iterator.
       for (CImg<float>::iterator it = img.begin(); it<img.end(); ++it)
         *it = 0;
       \endcode
    **/
    iterator end() {
      return _data + size();
    }

    //! Return a CImg<T>::iterator pointing next to the last pixel value \const.
    const_iterator end() const {
      return _data + size();
    }

    //! Return a reference to the first pixel value.
    /**
       \note
       - Writing \c img.front() is equivalent to <tt>img[0]</tt>, or <tt>img(0,0,0,0)</tt>.
       - It has been mainly defined for compatibility with STL naming conventions.
    **/
    T& front() {
      return *_data;
    }

    //! Return a reference to the first pixel value \const.
    const T& front() const {
      return *_data;
    }

    //! Return a reference to the last pixel value.
    /**
       \note
       - Writing \c img.back() is equivalent to <tt>img[img.size() - 1]</tt>, or
         <tt>img(img.width() - 1,img.height() - 1,img.depth() - 1,img.spectrum() - 1)</tt>.
       - It has been mainly defined for compatibility with STL naming conventions.
    **/
    T& back() {
      return *(_data + size() - 1);
    }

    //! Return a reference to the last pixel value \const.
    const T& back() const {
      return *(_data + size() - 1);
    }

    //! Access to a pixel value at a specified offset, using Dirichlet boundary conditions.
    /**
       Return a reference to the pixel value of the image instance located at a specified \c offset,
       or to a specified default value in case of out-of-bounds access.
       \param offset Offset to the desired pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note
       - Writing \c img.at(offset,out_value) is similar to <tt>img[offset]</tt>, except that if \c offset
         is outside bounds (e.g. \c offset<0 or \c offset>=img.size()), a reference to a value \c out_value
         is safely returned instead.
       - Due to the additional boundary checking operation, this function is slower than operator()(). Use it when
         you are \e not sure about the validity of the specified pixel offset.
    **/
    T& at(const int offset, const T& out_value) {
      return (offset<0 || offset>=(int)size())?(cimg::temporary(out_value)=out_value):(*this)[offset];
    }

    //! Access to a pixel value at a specified offset, using Dirichlet boundary conditions \const.
    T at(const int offset, const T& out_value) const {
      return (offset<0 || offset>=(int)size())?out_value:(*this)[offset];
    }

    //! Access to a pixel value at a specified offset, using Neumann boundary conditions.
    /**
       Return a reference to the pixel value of the image instance located at a specified \c offset,
       or to the nearest pixel location in the image instance in case of out-of-bounds access.
       \param offset Offset to the desired pixel value.
       \note
       - Similar to at(int,const T), except that an out-of-bounds access returns the value of the
         nearest pixel in the image instance, regarding the specified offset, i.e.
         - If \c offset<0, then \c img[0] is returned.
         - If \c offset>=img.size(), then \c img[img.size() - 1] is returned.
       - Due to the additional boundary checking operation, this function is slower than operator()(). Use it when
         you are \e not sure about the validity of the specified pixel offset.
       - If you know your image instance is \e not empty, you may rather use the slightly faster function \c _at(int).
     **/
    T& at(const int offset) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "at(): Empty instance.",
                                    cimg_instance);
      return _at(offset);
    }

    T& _at(const int offset) {
      const unsigned int siz = (unsigned int)size();
      return (*this)[offset<0?0:(unsigned int)offset>=siz?siz - 1:offset];
    }

    //! Access to a pixel value at a specified offset, using Neumann boundary conditions \const.
    const T& at(const int offset) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "at(): Empty instance.",
                                    cimg_instance);
      return _at(offset);
    }

    const T& _at(const int offset) const {
      const unsigned int siz = (unsigned int)size();
      return (*this)[offset<0?0:(unsigned int)offset>=siz?siz - 1:offset];
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X-coordinate.
    /**
       Return a reference to the pixel value of the image instance located at (\c x,\c y,\c z,\c c),
       or to a specified default value in case of out-of-bounds access along the X-axis.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c (\c x,\c y,\c z,\c c) is outside image bounds.
       \note
       - Similar to operator()(), except that an out-of-bounds access along the X-axis returns the specified value
         \c out_value.
       - Due to the additional boundary checking operation, this function is slower than operator()(). Use it when
         you are \e not sure about the validity of the specified pixel coordinates.
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
    **/
    T& atX(const int x, const int y, const int z, const int c, const T& out_value) {
      return (x<0 || x>=width())?(cimg::temporary(out_value)=out_value):(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X-coordinate \const.
    T atX(const int x, const int y, const int z, const int c, const T& out_value) const {
      return (x<0 || x>=width())?out_value:(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X-coordinate.
    /**
       Return a reference to the pixel value of the image instance located at (\c x,\c y,\c z,\c c),
       or to the nearest pixel location in the image instance in case of out-of-bounds access along the X-axis.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Similar to at(int,int,int,int,const T), except that an out-of-bounds access returns the value of the
         nearest pixel in the image instance, regarding the specified X-coordinate.
       - Due to the additional boundary checking operation, this function is slower than operator()(). Use it when
         you are \e not sure about the validity of the specified pixel coordinates.
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _at(int,int,int,int).
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
     **/
    T& atX(const int x, const int y=0, const int z=0, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atX(): Empty instance.",
                                    cimg_instance);
      return _atX(x,y,z,c);
    }

    T& _atX(const int x, const int y=0, const int z=0, const int c=0) {
      return (*this)(x<0?0:(x>=width()?width() - 1:x),y,z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X-coordinate \const.
    const T& atX(const int x, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atX(): Empty instance.",
                                    cimg_instance);
      return _atX(x,y,z,c);
    }

    const T& _atX(const int x, const int y=0, const int z=0, const int c=0) const {
      return (*this)(x<0?0:(x>=width()?width() - 1:x),y,z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X and Y-coordinates.
    /**
       Similar to atX(int,int,int,int,const T), except that boundary checking is performed both on X and Y-coordinates.
    **/
    T& atXY(const int x, const int y, const int z, const int c, const T& out_value) {
      return (x<0 || y<0 || x>=width() || y>=height())?(cimg::temporary(out_value)=out_value):(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X and Y coordinates \const.
    T atXY(const int x, const int y, const int z, const int c, const T& out_value) const {
      return (x<0 || y<0 || x>=width() || y>=height())?out_value:(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X and Y-coordinates.
    /**
       Similar to atX(int,int,int,int), except that boundary checking is performed both on X and Y-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _atXY(int,int,int,int).
     **/
    T& atXY(const int x, const int y, const int z=0, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXY(): Empty instance.",
                                    cimg_instance);
      return _atXY(x,y,z,c);
    }

    T& _atXY(const int x, const int y, const int z=0, const int c=0) {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X and Y-coordinates \const.
    const T& atXY(const int x, const int y, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXY(): Empty instance.",
                                    cimg_instance);
      return _atXY(x,y,z,c);
    }

    const T& _atXY(const int x, const int y, const int z=0, const int c=0) const {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to atX(int,int,int,int,const T), except that boundary checking is performed both on
       X,Y and Z-coordinates.
    **/
    T& atXYZ(const int x, const int y, const int z, const int c, const T& out_value) {
      return (x<0 || y<0 || z<0 || x>=width() || y>=height() || z>=depth())?
        (cimg::temporary(out_value)=out_value):(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions for the X,Y and Z-coordinates \const.
    T atXYZ(const int x, const int y, const int z, const int c, const T& out_value) const {
      return (x<0 || y<0 || z<0 || x>=width() || y>=height() || z>=depth())?out_value:(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to atX(int,int,int,int), except that boundary checking is performed both on X,Y and Z-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _atXYZ(int,int,int,int).
    **/
    T& atXYZ(const int x, const int y, const int z, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXYZ(): Empty instance.",
                                    cimg_instance);
      return _atXYZ(x,y,z,c);
    }

    T& _atXYZ(const int x, const int y, const int z, const int c=0) {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),
                     cimg::cut(z,0,depth() - 1),c);
    }

    //! Access to a pixel value, using Neumann boundary conditions for the X,Y and Z-coordinates \const.
    const T& atXYZ(const int x, const int y, const int z, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXYZ(): Empty instance.",
                                    cimg_instance);
      return _atXYZ(x,y,z,c);
    }

    const T& _atXYZ(const int x, const int y, const int z, const int c=0) const {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),
                     cimg::cut(z,0,depth() - 1),c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions.
    /**
       Similar to atX(int,int,int,int,const T), except that boundary checking is performed on all
       X,Y,Z and C-coordinates.
    **/
    T& atXYZC(const int x, const int y, const int z, const int c, const T& out_value) {
      return (x<0 || y<0 || z<0 || c<0 || x>=width() || y>=height() || z>=depth() || c>=spectrum())?
        (cimg::temporary(out_value)=out_value):(*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Dirichlet boundary conditions \const.
    T atXYZC(const int x, const int y, const int z, const int c, const T& out_value) const {
      return (x<0 || y<0 || z<0 || c<0 || x>=width() || y>=height() || z>=depth() || c>=spectrum())?out_value:
        (*this)(x,y,z,c);
    }

    //! Access to a pixel value, using Neumann boundary conditions.
    /**
       Similar to atX(int,int,int,int), except that boundary checking is performed on all X,Y,Z and C-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _atXYZC(int,int,int,int).
    **/
    T& atXYZC(const int x, const int y, const int z, const int c) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXYZC(): Empty instance.",
                                    cimg_instance);
      return _atXYZC(x,y,z,c);
    }

    T& _atXYZC(const int x, const int y, const int z, const int c) {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),
                     cimg::cut(z,0,depth() - 1),
                     cimg::cut(c,0,spectrum() - 1));
    }

    //! Access to a pixel value, using Neumann boundary conditions \const.
    const T& atXYZC(const int x, const int y, const int z, const int c) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "atXYZC(): Empty instance.",
                                    cimg_instance);
      return _atXYZC(x,y,z,c);
    }

    const T& _atXYZC(const int x, const int y, const int z, const int c) const {
      return (*this)(cimg::cut(x,0,width() - 1),
                     cimg::cut(y,0,height() - 1),
                     cimg::cut(z,0,depth() - 1),
                     cimg::cut(c,0,spectrum() - 1));
    }

    //! Return pixel value, using linear interpolation and Dirichlet boundary conditions for the X-coordinate.
    /**
       Return a linearly-interpolated pixel value of the image instance located at (\c fx,\c y,\c z,\c c),
       or a specified default value in case of out-of-bounds access along the X-axis.
       \param fx X-coordinate of the pixel value (float-valued).
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c (\c fx,\c y,\c z,\c c) is outside image bounds.
       \note
       - Similar to atX(int,int,int,int,const T), except that the returned pixel value is approximated by
         a linear interpolation along the X-axis, if corresponding coordinates are not integers.
       - The type of the returned pixel value is extended to \c float, if the pixel type \c T is not float-valued.
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
    **/
    Tfloat linear_atX(const float fx, const int y, const int z, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1;
      const float
        dx = fx - x;
      const Tfloat
        Ic = (Tfloat)atX(x,y,z,c,out_value), In = (Tfloat)atXY(nx,y,z,c,out_value);
      return Ic + dx*(In - Ic);
    }

    //! Return pixel value, using linear interpolation and Neumann boundary conditions for the X-coordinate.
    /**
       Return a linearly-interpolated pixel value of the image instance located at (\c fx,\c y,\c z,\c c),
       or the value of the nearest pixel location in the image instance in case of out-of-bounds access along
       the X-axis.
       \param fx X-coordinate of the pixel value (float-valued).
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Similar to linear_atX(float,int,int,int,const T) const, except that an out-of-bounds access returns
         the value of the nearest pixel in the image instance, regarding the specified X-coordinate.
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _linear_atX(float,int,int,int).
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
    **/
    Tfloat linear_atX(const float fx, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atX(): Empty instance.",
                                    cimg_instance);

      return _linear_atX(fx,y,z,c);
    }

    Tfloat _linear_atX(const float fx, const int y=0, const int z=0, const int c=0) const {
      const float
        nfx = cimg::cut(fx,0.f,width() - 1.f);
      const unsigned int
        x = (unsigned int)nfx;
      const float
        dx = nfx - x;
      const unsigned int
        nx = dx>0?x + 1:x;
      const Tfloat
        Ic = (Tfloat)(*this)(x,y,z,c), In = (Tfloat)(*this)(nx,y,z,c);
      return Ic + dx*(In - Ic);
    }

    //! Return pixel value, using linear interpolation and periodic boundary conditions for the X-coordinate.
    Tfloat linear_atX_p(const float fx, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atX_p(): Empty instance.",
                                    cimg_instance);

      return _linear_atX_p(fx,y,z,c);
    }

    Tfloat _linear_atX_p(const float fx, const int y=0, const int z=0, const int c=0) const {
      const float
        nfx = cimg::mod(fx,_width - 0.5f);
      const unsigned int
        x = (unsigned int)nfx;
      const float
        dx = nfx - x;
      const unsigned int
        nx = cimg::mod(x + 1,_width);
      const Tfloat
        Ic = (Tfloat)(*this)(x,y,z,c), In = (Tfloat)(*this)(nx,y,z,c);
      return Ic + dx*(In - Ic);
    }

    //! Return pixel value, using linear interpolation and Dirichlet boundary conditions for the X and Y-coordinates.
    /**
       Similar to linear_atX(float,int,int,int,const T) const, except that the linear interpolation and the
       boundary checking are achieved both for X and Y-coordinates.
    **/
    Tfloat linear_atXY(const float fx, const float fy, const int z, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1,
        y = (int)fy - (fy>=0?0:1), ny = y + 1;
      const float
        dx = fx - x,
        dy = fy - y;
      const Tfloat
        Icc = (Tfloat)atXY(x,y,z,c,out_value),  Inc = (Tfloat)atXY(nx,y,z,c,out_value),
        Icn = (Tfloat)atXY(x,ny,z,c,out_value), Inn = (Tfloat)atXY(nx,ny,z,c,out_value);
      return Icc + (Inc - Icc + (Icc + Inn - Icn - Inc)*dy)*dx + (Icn - Icc)*dy;
    }

    //! Return pixel value, using linear interpolation and Neumann boundary conditions for the X and Y-coordinates.
    /**
       Similar to linear_atX(float,int,int,int) const, except that the linear interpolation and the boundary checking
       are achieved both for X and Y-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _linear_atXY(float,float,int,int).
    **/
    Tfloat linear_atXY(const float fx, const float fy, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXY(): Empty instance.",
                                    cimg_instance);

      return _linear_atXY(fx,fy,z,c);
    }

    Tfloat _linear_atXY(const float fx, const float fy, const int z=0, const int c=0) const {
      const float
        nfx = cimg::cut(fx,0.f,width() - 1.f),
        nfy = cimg::cut(fy,0.f,height() - 1.f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy;
      const float
        dx = nfx - x,
        dy = nfy - y;
      const unsigned int
        nx = dx>0?x + 1:x,
        ny = dy>0?y + 1:y;
      const Tfloat
        Icc = (Tfloat)(*this)(x,y,z,c),  Inc = (Tfloat)(*this)(nx,y,z,c),
        Icn = (Tfloat)(*this)(x,ny,z,c), Inn = (Tfloat)(*this)(nx,ny,z,c);
      return Icc + (Inc - Icc + (Icc + Inn - Icn - Inc)*dy)*dx + (Icn - Icc)*dy;
    }

    //! Return pixel value, using linear interpolation and periodic boundary conditions for the X and Y-coordinates.
    Tfloat linear_atXY_p(const float fx, const float fy, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXY_p(): Empty instance.",
                                    cimg_instance);

      return _linear_atXY_p(fx,fy,z,c);
    }

    Tfloat _linear_atXY_p(const float fx, const float fy, const int z=0, const int c=0) const {
      const float
        nfx = cimg::mod(fx,_width - 0.5f),
        nfy = cimg::mod(fy,_height - 0.5f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy;
      const float
        dx = nfx - x,
        dy = nfy - y;
      const unsigned int
        nx = cimg::mod(x + 1,_width),
        ny = cimg::mod(y + 1,_height);
      const Tfloat
        Icc = (Tfloat)(*this)(x,y,z,c),  Inc = (Tfloat)(*this)(nx,y,z,c),
        Icn = (Tfloat)(*this)(x,ny,z,c), Inn = (Tfloat)(*this)(nx,ny,z,c);
      return Icc + (Inc - Icc + (Icc + Inn - Icn - Inc)*dy)*dx + (Icn - Icc)*dy;
    }

    //! Return pixel value, using linear interpolation and Dirichlet boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to linear_atX(float,int,int,int,const T) const, except that the linear interpolation and the
       boundary checking are achieved both for X,Y and Z-coordinates.
    **/
    Tfloat linear_atXYZ(const float fx, const float fy, const float fz, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1,
        y = (int)fy - (fy>=0?0:1), ny = y + 1,
        z = (int)fz - (fz>=0?0:1), nz = z + 1;
      const float
        dx = fx - x,
        dy = fy - y,
        dz = fz - z;
      const Tfloat
        Iccc = (Tfloat)atXYZ(x,y,z,c,out_value), Incc = (Tfloat)atXYZ(nx,y,z,c,out_value),
        Icnc = (Tfloat)atXYZ(x,ny,z,c,out_value), Innc = (Tfloat)atXYZ(nx,ny,z,c,out_value),
        Iccn = (Tfloat)atXYZ(x,y,nz,c,out_value), Incn = (Tfloat)atXYZ(nx,y,nz,c,out_value),
        Icnn = (Tfloat)atXYZ(x,ny,nz,c,out_value), Innn = (Tfloat)atXYZ(nx,ny,nz,c,out_value);
      return Iccc +
        (Incc - Iccc +
         (Iccc + Innc - Icnc - Incc +
          (Iccn + Innn + Icnc + Incc - Icnn - Incn - Iccc - Innc)*dz)*dy +
         (Iccc + Incn - Iccn - Incc)*dz)*dx +
        (Icnc - Iccc +
         (Iccc + Icnn - Iccn - Icnc)*dz)*dy +
        (Iccn - Iccc)*dz;
    }

    //! Return pixel value, using linear interpolation and Neumann boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to linear_atX(float,int,int,int) const, except that the linear interpolation and the boundary checking
       are achieved both for X,Y and Z-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _linear_atXYZ(float,float,float,int).
    **/
    Tfloat linear_atXYZ(const float fx, const float fy=0, const float fz=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXYZ(): Empty instance.",
                                    cimg_instance);

      return _linear_atXYZ(fx,fy,fz,c);
    }

    Tfloat _linear_atXYZ(const float fx, const float fy=0, const float fz=0, const int c=0) const {
      const float
        nfx = cimg::cut(fx,0.f,width() - 1.f),
        nfy = cimg::cut(fy,0.f,height() - 1.f),
        nfz = cimg::cut(fz,0.f,depth() - 1.f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy,
        z = (unsigned int)nfz;
      const float
        dx = nfx - x,
        dy = nfy - y,
        dz = nfz - z;
      const unsigned int
        nx = dx>0?x + 1:x,
        ny = dy>0?y + 1:y,
        nz = dz>0?z + 1:z;
      const Tfloat
        Iccc = (Tfloat)(*this)(x,y,z,c), Incc = (Tfloat)(*this)(nx,y,z,c),
        Icnc = (Tfloat)(*this)(x,ny,z,c), Innc = (Tfloat)(*this)(nx,ny,z,c),
        Iccn = (Tfloat)(*this)(x,y,nz,c), Incn = (Tfloat)(*this)(nx,y,nz,c),
        Icnn = (Tfloat)(*this)(x,ny,nz,c), Innn = (Tfloat)(*this)(nx,ny,nz,c);
      return Iccc +
        (Incc - Iccc +
         (Iccc + Innc - Icnc - Incc +
          (Iccn + Innn + Icnc + Incc - Icnn - Incn - Iccc - Innc)*dz)*dy +
         (Iccc + Incn - Iccn - Incc)*dz)*dx +
        (Icnc - Iccc +
         (Iccc + Icnn - Iccn - Icnc)*dz)*dy +
        (Iccn - Iccc)*dz;
    }

    //! Return pixel value, using linear interpolation and periodic boundary conditions for the X,Y and Z-coordinates.
    Tfloat linear_atXYZ_p(const float fx, const float fy=0, const float fz=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXYZ_p(): Empty instance.",
                                    cimg_instance);

      return _linear_atXYZ_p(fx,fy,fz,c);
    }

    Tfloat _linear_atXYZ_p(const float fx, const float fy=0, const float fz=0, const int c=0) const {
      const float
        nfx = cimg::mod(fx,_width - 0.5f),
        nfy = cimg::mod(fy,_height - 0.5f),
        nfz = cimg::mod(fz,_depth - 0.5f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy,
        z = (unsigned int)nfz;
      const float
        dx = nfx - x,
        dy = nfy - y,
        dz = nfz - z;
      const unsigned int
        nx = cimg::mod(x + 1,_width),
        ny = cimg::mod(y + 1,_height),
        nz = cimg::mod(z + 1,_depth);
      const Tfloat
        Iccc = (Tfloat)(*this)(x,y,z,c), Incc = (Tfloat)(*this)(nx,y,z,c),
        Icnc = (Tfloat)(*this)(x,ny,z,c), Innc = (Tfloat)(*this)(nx,ny,z,c),
        Iccn = (Tfloat)(*this)(x,y,nz,c), Incn = (Tfloat)(*this)(nx,y,nz,c),
        Icnn = (Tfloat)(*this)(x,ny,nz,c), Innn = (Tfloat)(*this)(nx,ny,nz,c);
      return Iccc +
        (Incc - Iccc +
         (Iccc + Innc - Icnc - Incc +
          (Iccn + Innn + Icnc + Incc - Icnn - Incn - Iccc - Innc)*dz)*dy +
         (Iccc + Incn - Iccn - Incc)*dz)*dx +
        (Icnc - Iccc +
         (Iccc + Icnn - Iccn - Icnc)*dz)*dy +
        (Iccn - Iccc)*dz;
    }

    //! Return pixel value, using linear interpolation and Dirichlet boundary conditions for all X,Y,Z,C-coordinates.
    /**
       Similar to linear_atX(float,int,int,int,const T) const, except that the linear interpolation and the
       boundary checking are achieved for all X,Y,Z and C-coordinates.
    **/
    Tfloat linear_atXYZC(const float fx, const float fy, const float fz, const float fc, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1,
        y = (int)fy - (fy>=0?0:1), ny = y + 1,
        z = (int)fz - (fz>=0?0:1), nz = z + 1,
        c = (int)fc - (fc>=0?0:1), nc = c + 1;
      const float
        dx = fx - x,
        dy = fy - y,
        dz = fz - z,
        dc = fc - c;
      const Tfloat
        Icccc = (Tfloat)atXYZC(x,y,z,c,out_value), Inccc = (Tfloat)atXYZC(nx,y,z,c,out_value),
        Icncc = (Tfloat)atXYZC(x,ny,z,c,out_value), Inncc = (Tfloat)atXYZC(nx,ny,z,c,out_value),
        Iccnc = (Tfloat)atXYZC(x,y,nz,c,out_value), Incnc = (Tfloat)atXYZC(nx,y,nz,c,out_value),
        Icnnc = (Tfloat)atXYZC(x,ny,nz,c,out_value), Innnc = (Tfloat)atXYZC(nx,ny,nz,c,out_value),
        Icccn = (Tfloat)atXYZC(x,y,z,nc,out_value), Inccn = (Tfloat)atXYZC(nx,y,z,nc,out_value),
        Icncn = (Tfloat)atXYZC(x,ny,z,nc,out_value), Inncn = (Tfloat)atXYZC(nx,ny,z,nc,out_value),
        Iccnn = (Tfloat)atXYZC(x,y,nz,nc,out_value), Incnn = (Tfloat)atXYZC(nx,y,nz,nc,out_value),
        Icnnn = (Tfloat)atXYZC(x,ny,nz,nc,out_value), Innnn = (Tfloat)atXYZC(nx,ny,nz,nc,out_value);
      return Icccc +
        dx*(Inccc - Icccc +
            dy*(Icccc + Inncc - Icncc - Inccc +
                dz*(Iccnc + Innnc + Icncc + Inccc - Icnnc - Incnc - Icccc - Inncc +
                    dc*(Iccnn + Innnn + Icncn + Inccn + Icnnc + Incnc + Icccc + Inncc -
                        Icnnn - Incnn - Icccn - Inncn - Iccnc - Innnc - Icncc - Inccc)) +
                dc*(Icccn + Inncn + Icncc + Inccc - Icncn - Inccn - Icccc - Inncc)) +
            dz*(Icccc + Incnc - Iccnc - Inccc +
                dc*(Icccn + Incnn + Iccnc + Inccc - Iccnn - Inccn - Icccc - Incnc)) +
            dc*(Icccc + Inccn - Inccc - Icccn)) +
        dy*(Icncc - Icccc +
            dz*(Icccc + Icnnc - Iccnc - Icncc +
                dc*(Icccn + Icnnn + Iccnc + Icncc - Iccnn - Icncn - Icccc - Icnnc)) +
            dc*(Icccc + Icncn - Icncc - Icccn)) +
        dz*(Iccnc - Icccc +
            dc*(Icccc + Iccnn - Iccnc - Icccn)) +
        dc*(Icccn  -Icccc);
    }

    //! Return pixel value, using linear interpolation and Neumann boundary conditions for all X,Y,Z and C-coordinates.
    /**
       Similar to linear_atX(float,int,int,int) const, except that the linear interpolation and the boundary checking
       are achieved for all X,Y,Z and C-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _linear_atXYZC(float,float,float,float).
    **/
    Tfloat linear_atXYZC(const float fx, const float fy=0, const float fz=0, const float fc=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXYZC(): Empty instance.",
                                    cimg_instance);

      return _linear_atXYZC(fx,fy,fz,fc);
    }

    Tfloat _linear_atXYZC(const float fx, const float fy=0, const float fz=0, const float fc=0) const {
      const float
        nfx = cimg::cut(fx,0.f,width() - 1.f),
        nfy = cimg::cut(fy,0.f,height() - 1.f),
        nfz = cimg::cut(fz,0.f,depth() - 1.f),
        nfc = cimg::cut(fc,0.f,spectrum() - 1.f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy,
        z = (unsigned int)nfz,
        c = (unsigned int)nfc;
      const float
        dx = nfx - x,
        dy = nfy - y,
        dz = nfz - z,
        dc = nfc - c;
      const unsigned int
        nx = dx>0?x + 1:x,
        ny = dy>0?y + 1:y,
        nz = dz>0?z + 1:z,
        nc = dc>0?c + 1:c;
      const Tfloat
        Icccc = (Tfloat)(*this)(x,y,z,c), Inccc = (Tfloat)(*this)(nx,y,z,c),
        Icncc = (Tfloat)(*this)(x,ny,z,c), Inncc = (Tfloat)(*this)(nx,ny,z,c),
        Iccnc = (Tfloat)(*this)(x,y,nz,c), Incnc = (Tfloat)(*this)(nx,y,nz,c),
        Icnnc = (Tfloat)(*this)(x,ny,nz,c), Innnc = (Tfloat)(*this)(nx,ny,nz,c),
        Icccn = (Tfloat)(*this)(x,y,z,nc), Inccn = (Tfloat)(*this)(nx,y,z,nc),
        Icncn = (Tfloat)(*this)(x,ny,z,nc), Inncn = (Tfloat)(*this)(nx,ny,z,nc),
        Iccnn = (Tfloat)(*this)(x,y,nz,nc), Incnn = (Tfloat)(*this)(nx,y,nz,nc),
        Icnnn = (Tfloat)(*this)(x,ny,nz,nc), Innnn = (Tfloat)(*this)(nx,ny,nz,nc);
      return Icccc +
        dx*(Inccc - Icccc +
            dy*(Icccc + Inncc - Icncc - Inccc +
                dz*(Iccnc + Innnc + Icncc + Inccc - Icnnc - Incnc - Icccc - Inncc +
                    dc*(Iccnn + Innnn + Icncn + Inccn + Icnnc + Incnc + Icccc + Inncc -
                        Icnnn - Incnn - Icccn - Inncn - Iccnc - Innnc - Icncc - Inccc)) +
                dc*(Icccn + Inncn + Icncc + Inccc - Icncn - Inccn - Icccc - Inncc)) +
            dz*(Icccc + Incnc - Iccnc - Inccc +
                dc*(Icccn + Incnn + Iccnc + Inccc - Iccnn - Inccn - Icccc - Incnc)) +
            dc*(Icccc + Inccn - Inccc - Icccn)) +
        dy*(Icncc - Icccc +
            dz*(Icccc + Icnnc - Iccnc - Icncc +
                dc*(Icccn + Icnnn + Iccnc + Icncc - Iccnn - Icncn - Icccc - Icnnc)) +
            dc*(Icccc + Icncn - Icncc - Icccn)) +
        dz*(Iccnc - Icccc +
            dc*(Icccc + Iccnn - Iccnc - Icccn)) +
        dc*(Icccn - Icccc);
    }

    //! Return pixel value, using linear interpolation and periodic boundary conditions for all X,Y,Z and C-coordinates.
    Tfloat linear_atXYZC_p(const float fx, const float fy=0, const float fz=0, const float fc=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "linear_atXYZC_p(): Empty instance.",
                                    cimg_instance);

      return _linear_atXYZC_p(fx,fy,fz,fc);
    }

    Tfloat _linear_atXYZC_p(const float fx, const float fy=0, const float fz=0, const float fc=0) const {
      const float
        nfx = cimg::mod(fx,_width - 0.5f),
        nfy = cimg::mod(fy,_height - 0.5f),
        nfz = cimg::mod(fz,_depth - 0.5f),
        nfc = cimg::mod(fc,_spectrum - 0.5f);
      const unsigned int
        x = (unsigned int)nfx,
        y = (unsigned int)nfy,
        z = (unsigned int)nfz,
        c = (unsigned int)nfc;
      const float
        dx = nfx - x,
        dy = nfy - y,
        dz = nfz - z,
        dc = nfc - c;
      const unsigned int
        nx = cimg::mod(x + 1,_width),
        ny = cimg::mod(y + 1,_height),
        nz = cimg::mod(z + 1,_depth),
        nc = cimg::mod(c + 1,_spectrum);
      const Tfloat
        Icccc = (Tfloat)(*this)(x,y,z,c), Inccc = (Tfloat)(*this)(nx,y,z,c),
        Icncc = (Tfloat)(*this)(x,ny,z,c), Inncc = (Tfloat)(*this)(nx,ny,z,c),
        Iccnc = (Tfloat)(*this)(x,y,nz,c), Incnc = (Tfloat)(*this)(nx,y,nz,c),
        Icnnc = (Tfloat)(*this)(x,ny,nz,c), Innnc = (Tfloat)(*this)(nx,ny,nz,c),
        Icccn = (Tfloat)(*this)(x,y,z,nc), Inccn = (Tfloat)(*this)(nx,y,z,nc),
        Icncn = (Tfloat)(*this)(x,ny,z,nc), Inncn = (Tfloat)(*this)(nx,ny,z,nc),
        Iccnn = (Tfloat)(*this)(x,y,nz,nc), Incnn = (Tfloat)(*this)(nx,y,nz,nc),
        Icnnn = (Tfloat)(*this)(x,ny,nz,nc), Innnn = (Tfloat)(*this)(nx,ny,nz,nc);
      return Icccc +
        dx*(Inccc - Icccc +
            dy*(Icccc + Inncc - Icncc - Inccc +
                dz*(Iccnc + Innnc + Icncc + Inccc - Icnnc - Incnc - Icccc - Inncc +
                    dc*(Iccnn + Innnn + Icncn + Inccn + Icnnc + Incnc + Icccc + Inncc -
                        Icnnn - Incnn - Icccn - Inncn - Iccnc - Innnc - Icncc - Inccc)) +
                dc*(Icccn + Inncn + Icncc + Inccc - Icncn - Inccn - Icccc - Inncc)) +
            dz*(Icccc + Incnc - Iccnc - Inccc +
                dc*(Icccn + Incnn + Iccnc + Inccc - Iccnn - Inccn - Icccc - Incnc)) +
            dc*(Icccc + Inccn - Inccc - Icccn)) +
        dy*(Icncc - Icccc +
            dz*(Icccc + Icnnc - Iccnc - Icncc +
                dc*(Icccn + Icnnn + Iccnc + Icncc - Iccnn - Icncn - Icccc - Icnnc)) +
            dc*(Icccc + Icncn - Icncc - Icccn)) +
        dz*(Iccnc - Icccc +
            dc*(Icccc + Iccnn - Iccnc - Icccn)) +
        dc*(Icccn - Icccc);
    }

    //! Return pixel value, using cubic interpolation and Dirichlet boundary conditions for the X-coordinate.
    /**
       Return a cubicly-interpolated pixel value of the image instance located at (\c fx,\c y,\c z,\c c),
       or a specified default value in case of out-of-bounds access along the X-axis.
       The cubic interpolation uses Hermite splines.
       \param fx d X-coordinate of the pixel value (float-valued).
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c (\c fx,\c y,\c z,\c c) is outside image bounds.
       \note
       - Similar to linear_atX(float,int,int,int,const T) const, except that the returned pixel value is
         approximated by a \e cubic interpolation along the X-axis.
       - The type of the returned pixel value is extended to \c float, if the pixel type \c T is not float-valued.
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
    **/
    Tfloat cubic_atX(const float fx, const int y, const int z, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), px = x - 1, nx = x + 1, ax = x + 2;
      const float
        dx = fx - x;
      const Tfloat
        Ip = (Tfloat)atX(px,y,z,c,out_value), Ic = (Tfloat)atX(x,y,z,c,out_value),
        In = (Tfloat)atX(nx,y,z,c,out_value), Ia = (Tfloat)atX(ax,y,z,c,out_value);
      return Ic + 0.5f*(dx*(-Ip + In) + dx*dx*(2*Ip - 5*Ic + 4*In - Ia) + dx*dx*dx*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Dirichlet boundary conditions for the X-coordinate.
    /**
       Similar to cubic_atX(float,int,int,int,const T) const, except that the return value is clamped to stay in the
       min/max range of the datatype \c T.
    **/
    T cubic_atX_c(const float fx, const int y, const int z, const int c, const T& out_value) const {
      return cimg::type<T>::cut(cubic_atX(fx,y,z,c,out_value));
    }

    //! Return pixel value, using cubic interpolation and Neumann boundary conditions for the X-coordinate.
    /**
       Return a cubicly-interpolated pixel value of the image instance located at (\c fx,\c y,\c z,\c c),
       or the value of the nearest pixel location in the image instance in case of out-of-bounds access
       along the X-axis. The cubic interpolation uses Hermite splines.
       \param fx X-coordinate of the pixel value (float-valued).
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Similar to cubic_atX(float,int,int,int,const T) const, except that the returned pixel value is
         approximated by a cubic interpolation along the X-axis.
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _cubic_atX(float,int,int,int).
       \warning
       - There is \e no boundary checking performed for the Y,Z and C-coordinates, so they must be inside image bounds.
    **/
    Tfloat cubic_atX(const float fx, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atX(): Empty instance.",
                                    cimg_instance);
      return _cubic_atX(fx,y,z,c);
    }

    Tfloat _cubic_atX(const float fx, const int y=0, const int z=0, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::cut(fx,0.f,width() - 1.f);
      const int
        x = (int)nfx;
      const float
        dx = nfx - x;
      const int
        px = x - 1<0?0:x - 1, nx = dx>0?x + 1:x, ax = x + 2>=width()?width() - 1:x + 2;
      const Tfloat
        Ip = (Tfloat)(*this)(px,y,z,c), Ic = (Tfloat)(*this)(x,y,z,c),
        In = (Tfloat)(*this)(nx,y,z,c), Ia = (Tfloat)(*this)(ax,y,z,c);
      return Ic + 0.5f*(dx*(-Ip + In) + dx*dx*(2*Ip - 5*Ic + 4*In - Ia) + dx*dx*dx*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Neumann boundary conditions for the X-coordinate.
    /**
       Similar to cubic_atX(float,int,int,int) const, except that the return value is clamped to stay in the
       min/max range of the datatype \c T.
    **/
    T cubic_atX_c(const float fx, const int y, const int z, const int c) const {
      return cimg::type<T>::cut(cubic_atX(fx,y,z,c));
    }

    T _cubic_atX_c(const float fx, const int y, const int z, const int c) const {
      return cimg::type<T>::cut(_cubic_atX(fx,y,z,c));
    }

    //! Return pixel value, using cubic interpolation and periodic boundary conditions for the X-coordinate.
    Tfloat cubic_atX_p(const float fx, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atX_p(): Empty instance.",
                                    cimg_instance);
      return _cubic_atX_p(fx,y,z,c);
    }

    Tfloat _cubic_atX_p(const float fx, const int y=0, const int z=0, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::mod(fx,_width - 0.5f);
      const int
        x = (int)nfx;
      const float
        dx = nfx - x;
      const int
        px = cimg::mod(x - 1,width()), nx = cimg::mod(x + 1,width()), ax = cimg::mod(x + 2,width());
      const Tfloat
        Ip = (Tfloat)(*this)(px,y,z,c), Ic = (Tfloat)(*this)(x,y,z,c),
        In = (Tfloat)(*this)(nx,y,z,c), Ia = (Tfloat)(*this)(ax,y,z,c);
      return Ic + 0.5f*(dx*(-Ip + In) + dx*dx*(2*Ip - 5*Ic + 4*In - Ia) + dx*dx*dx*(-Ip + 3*Ic - 3*In + Ia));
    }

    T cubic_atX_pc(const float fx, const int y, const int z, const int c) const {
      return cimg::type<T>::cut(cubic_atX_p(fx,y,z,c));
    }

    T _cubic_atX_pc(const float fx, const int y, const int z, const int c) const {
      return cimg::type<T>::cut(_cubic_atX_p(fx,y,z,c));
    }

    //! Return pixel value, using cubic interpolation and Dirichlet boundary conditions for the X and Y-coordinates.
    /**
       Similar to cubic_atX(float,int,int,int,const T) const, except that the cubic interpolation and boundary checking
       are achieved both for X and Y-coordinates.
    **/
    Tfloat cubic_atXY(const float fx, const float fy, const int z, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), px = x - 1, nx = x + 1, ax = x + 2,
        y = (int)fy - (fy>=0?0:1), py = y - 1, ny = y + 1, ay = y + 2;
      const float dx = fx - x, dy = fy - y;
      const Tfloat
        Ipp = (Tfloat)atXY(px,py,z,c,out_value), Icp = (Tfloat)atXY(x,py,z,c,out_value),
        Inp = (Tfloat)atXY(nx,py,z,c,out_value), Iap = (Tfloat)atXY(ax,py,z,c,out_value),
        Ip = Icp + 0.5f*(dx*(-Ipp + Inp) + dx*dx*(2*Ipp - 5*Icp + 4*Inp - Iap) + dx*dx*dx*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ipc = (Tfloat)atXY(px,y,z,c,out_value),  Icc = (Tfloat)atXY(x, y,z,c,out_value),
        Inc = (Tfloat)atXY(nx,y,z,c,out_value),  Iac = (Tfloat)atXY(ax,y,z,c,out_value),
        Ic = Icc + 0.5f*(dx*(-Ipc + Inc) + dx*dx*(2*Ipc - 5*Icc + 4*Inc - Iac) + dx*dx*dx*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ipn = (Tfloat)atXY(px,ny,z,c,out_value), Icn = (Tfloat)atXY(x,ny,z,c,out_value),
        Inn = (Tfloat)atXY(nx,ny,z,c,out_value), Ian = (Tfloat)atXY(ax,ny,z,c,out_value),
        In = Icn + 0.5f*(dx*(-Ipn + Inn) + dx*dx*(2*Ipn - 5*Icn + 4*Inn - Ian) + dx*dx*dx*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ipa = (Tfloat)atXY(px,ay,z,c,out_value), Ica = (Tfloat)atXY(x,ay,z,c,out_value),
        Ina = (Tfloat)atXY(nx,ay,z,c,out_value), Iaa = (Tfloat)atXY(ax,ay,z,c,out_value),
        Ia = Ica + 0.5f*(dx*(-Ipa + Ina) + dx*dx*(2*Ipa - 5*Ica + 4*Ina - Iaa) + dx*dx*dx*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dy*(-Ip + In) + dy*dy*(2*Ip - 5*Ic + 4*In - Ia) + dy*dy*dy*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Dirichlet boundary conditions for the X,Y-coordinates.
    /**
       Similar to cubic_atXY(float,float,int,int,const T) const, except that the return value is clamped to stay in the
       min/max range of the datatype \c T.
    **/
    T cubic_atXY_c(const float fx, const float fy, const int z, const int c, const T& out_value) const {
      return cimg::type<T>::cut(cubic_atXY(fx,fy,z,c,out_value));
    }

    //! Return pixel value, using cubic interpolation and Neumann boundary conditions for the X and Y-coordinates.
    /**
       Similar to cubic_atX(float,int,int,int) const, except that the cubic interpolation and boundary checking
       are achieved for both X and Y-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
       \c _cubic_atXY(float,float,int,int).
    **/
    Tfloat cubic_atXY(const float fx, const float fy, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atXY(): Empty instance.",
                                    cimg_instance);
      return _cubic_atXY(fx,fy,z,c);
    }

    Tfloat _cubic_atXY(const float fx, const float fy, const int z=0, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::cut(fx,0.f,width() - 1.f),
        nfy = cimg::type<float>::is_nan(fy)?0:cimg::cut(fy,0.f,height() - 1.f);
      const int x = (int)nfx, y = (int)nfy;
      const float dx = nfx - x, dy = nfy - y;
      const int
        px = x - 1<0?0:x - 1, nx = dx<=0?x:x + 1, ax = x + 2>=width()?width() - 1:x + 2,
        py = y - 1<0?0:y - 1, ny = dy<=0?y:y + 1, ay = y + 2>=height()?height() - 1:y + 2;
      const Tfloat
        Ipp = (Tfloat)(*this)(px,py,z,c), Icp = (Tfloat)(*this)(x,py,z,c), Inp = (Tfloat)(*this)(nx,py,z,c),
        Iap = (Tfloat)(*this)(ax,py,z,c),
        Ip = Icp + 0.5f*(dx*(-Ipp + Inp) + dx*dx*(2*Ipp - 5*Icp + 4*Inp - Iap) + dx*dx*dx*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ipc = (Tfloat)(*this)(px,y,z,c),  Icc = (Tfloat)(*this)(x, y,z,c), Inc = (Tfloat)(*this)(nx,y,z,c),
        Iac = (Tfloat)(*this)(ax,y,z,c),
        Ic = Icc + 0.5f*(dx*(-Ipc + Inc) + dx*dx*(2*Ipc - 5*Icc + 4*Inc - Iac) + dx*dx*dx*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ipn = (Tfloat)(*this)(px,ny,z,c), Icn = (Tfloat)(*this)(x,ny,z,c), Inn = (Tfloat)(*this)(nx,ny,z,c),
        Ian = (Tfloat)(*this)(ax,ny,z,c),
        In = Icn + 0.5f*(dx*(-Ipn + Inn) + dx*dx*(2*Ipn - 5*Icn + 4*Inn - Ian) + dx*dx*dx*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ipa = (Tfloat)(*this)(px,ay,z,c), Ica = (Tfloat)(*this)(x,ay,z,c), Ina = (Tfloat)(*this)(nx,ay,z,c),
        Iaa = (Tfloat)(*this)(ax,ay,z,c),
        Ia = Ica + 0.5f*(dx*(-Ipa + Ina) + dx*dx*(2*Ipa - 5*Ica + 4*Ina - Iaa) + dx*dx*dx*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dy*(-Ip + In) + dy*dy*(2*Ip - 5*Ic + 4*In - Ia) + dy*dy*dy*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Neumann boundary conditions for the X,Y-coordinates.
    /**
       Similar to cubic_atXY(float,float,int,int) const, except that the return value is clamped to stay in the
       min/max range of the datatype \c T.
    **/
    T cubic_atXY_c(const float fx, const float fy, const int z, const int c) const {
      return cimg::type<T>::cut(cubic_atXY(fx,fy,z,c));
    }

    T _cubic_atXY_c(const float fx, const float fy, const int z, const int c) const {
      return cimg::type<T>::cut(_cubic_atXY(fx,fy,z,c));
    }

    //! Return pixel value, using cubic interpolation and periodic boundary conditions for the X and Y-coordinates.
    Tfloat cubic_atXY_p(const float fx, const float fy, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atXY_p(): Empty instance.",
                                    cimg_instance);
      return _cubic_atXY_p(fx,fy,z,c);
    }

    Tfloat _cubic_atXY_p(const float fx, const float fy, const int z=0, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::mod(fx,_width - 0.5f),
        nfy = cimg::type<float>::is_nan(fy)?0:cimg::mod(fy,_height - 0.5f);
      const int x = (int)nfx, y = (int)nfy;
      const float dx = nfx - x, dy = nfy - y;
      const int
        px = cimg::mod(x - 1,width()), nx = cimg::mod(x + 1,width()), ax = cimg::mod(x + 2,width()),
        py = cimg::mod(y - 1,height()), ny = cimg::mod(y + 1,height()), ay = cimg::mod(y + 2,height());
      const Tfloat
        Ipp = (Tfloat)(*this)(px,py,z,c), Icp = (Tfloat)(*this)(x,py,z,c), Inp = (Tfloat)(*this)(nx,py,z,c),
        Iap = (Tfloat)(*this)(ax,py,z,c),
        Ip = Icp + 0.5f*(dx*(-Ipp + Inp) + dx*dx*(2*Ipp - 5*Icp + 4*Inp - Iap) + dx*dx*dx*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ipc = (Tfloat)(*this)(px,y,z,c),  Icc = (Tfloat)(*this)(x, y,z,c), Inc = (Tfloat)(*this)(nx,y,z,c),
        Iac = (Tfloat)(*this)(ax,y,z,c),
        Ic = Icc + 0.5f*(dx*(-Ipc + Inc) + dx*dx*(2*Ipc - 5*Icc + 4*Inc - Iac) + dx*dx*dx*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ipn = (Tfloat)(*this)(px,ny,z,c), Icn = (Tfloat)(*this)(x,ny,z,c), Inn = (Tfloat)(*this)(nx,ny,z,c),
        Ian = (Tfloat)(*this)(ax,ny,z,c),
        In = Icn + 0.5f*(dx*(-Ipn + Inn) + dx*dx*(2*Ipn - 5*Icn + 4*Inn - Ian) + dx*dx*dx*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ipa = (Tfloat)(*this)(px,ay,z,c), Ica = (Tfloat)(*this)(x,ay,z,c), Ina = (Tfloat)(*this)(nx,ay,z,c),
        Iaa = (Tfloat)(*this)(ax,ay,z,c),
        Ia = Ica + 0.5f*(dx*(-Ipa + Ina) + dx*dx*(2*Ipa - 5*Ica + 4*Ina - Iaa) + dx*dx*dx*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dy*(-Ip + In) + dy*dy*(2*Ip - 5*Ic + 4*In - Ia) + dy*dy*dy*(-Ip + 3*Ic - 3*In + Ia));
    }

    T cubic_atXY_pc(const float fx, const float fy, const int z, const int c) const {
      return cimg::type<T>::cut(cubic_atXY_p(fx,fy,z,c));
    }

    T _cubic_atXY_pc(const float fx, const float fy, const int z, const int c) const {
      return cimg::type<T>::cut(_cubic_atXY_p(fx,fy,z,c));
    }

    //! Return pixel value, using cubic interpolation and Dirichlet boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to cubic_atX(float,int,int,int,const T) const, except that the cubic interpolation and boundary checking
       are achieved both for X,Y and Z-coordinates.
    **/
    Tfloat cubic_atXYZ(const float fx, const float fy, const float fz, const int c, const T& out_value) const {
      const int
        x = (int)fx - (fx>=0?0:1), px = x - 1, nx = x + 1, ax = x + 2,
        y = (int)fy - (fy>=0?0:1), py = y - 1, ny = y + 1, ay = y + 2,
        z = (int)fz - (fz>=0?0:1), pz = z - 1, nz = z + 1, az = z + 2;
      const float dx = fx - x, dy = fy - y, dz = fz - z;
      const Tfloat
        Ippp = (Tfloat)atXYZ(px,py,pz,c,out_value), Icpp = (Tfloat)atXYZ(x,py,pz,c,out_value),
        Inpp = (Tfloat)atXYZ(nx,py,pz,c,out_value), Iapp = (Tfloat)atXYZ(ax,py,pz,c,out_value),
        Ipp = Icpp + 0.5f*(dx*(-Ippp + Inpp) + dx*dx*(2*Ippp - 5*Icpp + 4*Inpp - Iapp) +
                           dx*dx*dx*(-Ippp + 3*Icpp - 3*Inpp + Iapp)),
        Ipcp = (Tfloat)atXYZ(px,y,pz,c,out_value),  Iccp = (Tfloat)atXYZ(x, y,pz,c,out_value),
        Incp = (Tfloat)atXYZ(nx,y,pz,c,out_value),  Iacp = (Tfloat)atXYZ(ax,y,pz,c,out_value),
        Icp = Iccp + 0.5f*(dx*(-Ipcp + Incp) + dx*dx*(2*Ipcp - 5*Iccp + 4*Incp - Iacp) +
                           dx*dx*dx*(-Ipcp + 3*Iccp - 3*Incp + Iacp)),
        Ipnp = (Tfloat)atXYZ(px,ny,pz,c,out_value), Icnp = (Tfloat)atXYZ(x,ny,pz,c,out_value),
        Innp = (Tfloat)atXYZ(nx,ny,pz,c,out_value), Ianp = (Tfloat)atXYZ(ax,ny,pz,c,out_value),
        Inp = Icnp + 0.5f*(dx*(-Ipnp + Innp) + dx*dx*(2*Ipnp - 5*Icnp + 4*Innp - Ianp) +
                           dx*dx*dx*(-Ipnp + 3*Icnp - 3*Innp + Ianp)),
        Ipap = (Tfloat)atXYZ(px,ay,pz,c,out_value), Icap = (Tfloat)atXYZ(x,ay,pz,c,out_value),
        Inap = (Tfloat)atXYZ(nx,ay,pz,c,out_value), Iaap = (Tfloat)atXYZ(ax,ay,pz,c,out_value),
        Iap = Icap + 0.5f*(dx*(-Ipap + Inap) + dx*dx*(2*Ipap - 5*Icap + 4*Inap - Iaap) +
                           dx*dx*dx*(-Ipap + 3*Icap - 3*Inap + Iaap)),
        Ip = Icp + 0.5f*(dy*(-Ipp + Inp) + dy*dy*(2*Ipp - 5*Icp + 4*Inp - Iap) +
                         dy*dy*dy*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ippc = (Tfloat)atXYZ(px,py,z,c,out_value), Icpc = (Tfloat)atXYZ(x,py,z,c,out_value),
        Inpc = (Tfloat)atXYZ(nx,py,z,c,out_value), Iapc = (Tfloat)atXYZ(ax,py,z,c,out_value),
        Ipc = Icpc + 0.5f*(dx*(-Ippc + Inpc) + dx*dx*(2*Ippc - 5*Icpc + 4*Inpc - Iapc) +
                           dx*dx*dx*(-Ippc + 3*Icpc - 3*Inpc + Iapc)),
        Ipcc = (Tfloat)atXYZ(px,y,z,c,out_value),  Iccc = (Tfloat)atXYZ(x, y,z,c,out_value),
        Incc = (Tfloat)atXYZ(nx,y,z,c,out_value),  Iacc = (Tfloat)atXYZ(ax,y,z,c,out_value),
        Icc = Iccc + 0.5f*(dx*(-Ipcc + Incc) + dx*dx*(2*Ipcc - 5*Iccc + 4*Incc - Iacc) +
                           dx*dx*dx*(-Ipcc + 3*Iccc - 3*Incc + Iacc)),
        Ipnc = (Tfloat)atXYZ(px,ny,z,c,out_value), Icnc = (Tfloat)atXYZ(x,ny,z,c,out_value),
        Innc = (Tfloat)atXYZ(nx,ny,z,c,out_value), Ianc = (Tfloat)atXYZ(ax,ny,z,c,out_value),
        Inc = Icnc + 0.5f*(dx*(-Ipnc + Innc) + dx*dx*(2*Ipnc - 5*Icnc + 4*Innc - Ianc) +
                           dx*dx*dx*(-Ipnc + 3*Icnc - 3*Innc + Ianc)),
        Ipac = (Tfloat)atXYZ(px,ay,z,c,out_value), Icac = (Tfloat)atXYZ(x,ay,z,c,out_value),
        Inac = (Tfloat)atXYZ(nx,ay,z,c,out_value), Iaac = (Tfloat)atXYZ(ax,ay,z,c,out_value),
        Iac = Icac + 0.5f*(dx*(-Ipac + Inac) + dx*dx*(2*Ipac - 5*Icac + 4*Inac - Iaac) +
                           dx*dx*dx*(-Ipac + 3*Icac - 3*Inac + Iaac)),
        Ic = Icc + 0.5f*(dy*(-Ipc + Inc) + dy*dy*(2*Ipc - 5*Icc + 4*Inc - Iac) +
                         dy*dy*dy*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ippn = (Tfloat)atXYZ(px,py,nz,c,out_value), Icpn = (Tfloat)atXYZ(x,py,nz,c,out_value),
        Inpn = (Tfloat)atXYZ(nx,py,nz,c,out_value), Iapn = (Tfloat)atXYZ(ax,py,nz,c,out_value),
        Ipn = Icpn + 0.5f*(dx*(-Ippn + Inpn) + dx*dx*(2*Ippn - 5*Icpn + 4*Inpn - Iapn) +
                           dx*dx*dx*(-Ippn + 3*Icpn - 3*Inpn + Iapn)),
        Ipcn = (Tfloat)atXYZ(px,y,nz,c,out_value),  Iccn = (Tfloat)atXYZ(x, y,nz,c,out_value),
        Incn = (Tfloat)atXYZ(nx,y,nz,c,out_value),  Iacn = (Tfloat)atXYZ(ax,y,nz,c,out_value),
        Icn = Iccn + 0.5f*(dx*(-Ipcn + Incn) + dx*dx*(2*Ipcn - 5*Iccn + 4*Incn - Iacn) +
                           dx*dx*dx*(-Ipcn + 3*Iccn - 3*Incn + Iacn)),
        Ipnn = (Tfloat)atXYZ(px,ny,nz,c,out_value), Icnn = (Tfloat)atXYZ(x,ny,nz,c,out_value),
        Innn = (Tfloat)atXYZ(nx,ny,nz,c,out_value), Iann = (Tfloat)atXYZ(ax,ny,nz,c,out_value),
        Inn = Icnn + 0.5f*(dx*(-Ipnn + Innn) + dx*dx*(2*Ipnn - 5*Icnn + 4*Innn - Iann) +
                           dx*dx*dx*(-Ipnn + 3*Icnn - 3*Innn + Iann)),
        Ipan = (Tfloat)atXYZ(px,ay,nz,c,out_value), Ican = (Tfloat)atXYZ(x,ay,nz,c,out_value),
        Inan = (Tfloat)atXYZ(nx,ay,nz,c,out_value), Iaan = (Tfloat)atXYZ(ax,ay,nz,c,out_value),
        Ian = Ican + 0.5f*(dx*(-Ipan + Inan) + dx*dx*(2*Ipan - 5*Ican + 4*Inan - Iaan) +
                           dx*dx*dx*(-Ipan + 3*Ican - 3*Inan + Iaan)),
        In = Icn + 0.5f*(dy*(-Ipn + Inn) + dy*dy*(2*Ipn - 5*Icn + 4*Inn - Ian) +
                         dy*dy*dy*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ippa = (Tfloat)atXYZ(px,py,az,c,out_value), Icpa = (Tfloat)atXYZ(x,py,az,c,out_value),
        Inpa = (Tfloat)atXYZ(nx,py,az,c,out_value), Iapa = (Tfloat)atXYZ(ax,py,az,c,out_value),
        Ipa = Icpa + 0.5f*(dx*(-Ippa + Inpa) + dx*dx*(2*Ippa - 5*Icpa + 4*Inpa - Iapa) +
                           dx*dx*dx*(-Ippa + 3*Icpa - 3*Inpa + Iapa)),
        Ipca = (Tfloat)atXYZ(px,y,az,c,out_value),  Icca = (Tfloat)atXYZ(x, y,az,c,out_value),
        Inca = (Tfloat)atXYZ(nx,y,az,c,out_value),  Iaca = (Tfloat)atXYZ(ax,y,az,c,out_value),
        Ica = Icca + 0.5f*(dx*(-Ipca + Inca) + dx*dx*(2*Ipca - 5*Icca + 4*Inca - Iaca) +
                           dx*dx*dx*(-Ipca + 3*Icca - 3*Inca + Iaca)),
        Ipna = (Tfloat)atXYZ(px,ny,az,c,out_value), Icna = (Tfloat)atXYZ(x,ny,az,c,out_value),
        Inna = (Tfloat)atXYZ(nx,ny,az,c,out_value), Iana = (Tfloat)atXYZ(ax,ny,az,c,out_value),
        Ina = Icna + 0.5f*(dx*(-Ipna + Inna) + dx*dx*(2*Ipna - 5*Icna + 4*Inna - Iana) +
                           dx*dx*dx*(-Ipna + 3*Icna - 3*Inna + Iana)),
        Ipaa = (Tfloat)atXYZ(px,ay,az,c,out_value), Icaa = (Tfloat)atXYZ(x,ay,az,c,out_value),
        Inaa = (Tfloat)atXYZ(nx,ay,az,c,out_value), Iaaa = (Tfloat)atXYZ(ax,ay,az,c,out_value),
        Iaa = Icaa + 0.5f*(dx*(-Ipaa + Inaa) + dx*dx*(2*Ipaa - 5*Icaa + 4*Inaa - Iaaa) +
                           dx*dx*dx*(-Ipaa + 3*Icaa - 3*Inaa + Iaaa)),
        Ia = Ica + 0.5f*(dy*(-Ipa + Ina) + dy*dy*(2*Ipa - 5*Ica + 4*Ina - Iaa) +
                         dy*dy*dy*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dz*(-Ip + In) + dz*dz*(2*Ip - 5*Ic + 4*In - Ia) + dz*dz*dz*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Dirichlet boundary conditions for the XYZ-coordinates.
    /**
       Similar to cubic_atXYZ(float,float,float,int,const T) const, except that the return value is clamped to stay
       in the min/max range of the datatype \c T.
    **/
    T cubic_atXYZ_c(const float fx, const float fy, const float fz, const int c, const T& out_value) const {
      return cimg::type<T>::cut(cubic_atXYZ(fx,fy,fz,c,out_value));
    }

    //! Return pixel value, using cubic interpolation and Neumann boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to cubic_atX(float,int,int,int) const, except that the cubic interpolation and boundary checking
       are achieved both for X,Y and Z-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _cubic_atXYZ(float,float,float,int).
    **/
    Tfloat cubic_atXYZ(const float fx, const float fy, const float fz, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atXYZ(): Empty instance.",
                                    cimg_instance);
      return _cubic_atXYZ(fx,fy,fz,c);
    }

    Tfloat _cubic_atXYZ(const float fx, const float fy, const float fz, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::cut(fx,0.f,width() - 1.f),
        nfy = cimg::type<float>::is_nan(fy)?0:cimg::cut(fy,0.f,height() - 1.f),
        nfz = cimg::type<float>::is_nan(fz)?0:cimg::cut(fz,0.f,depth() - 1.f);
      const int x = (int)nfx, y = (int)nfy, z = (int)nfz;
      const float dx = nfx - x, dy = nfy - y, dz = nfz - z;
      const int
        px = x - 1<0?0:x - 1, nx = dx>0?x + 1:x, ax = x + 2>=width()?width() - 1:x + 2,
        py = y - 1<0?0:y - 1, ny = dy>0?y + 1:y, ay = y + 2>=height()?height() - 1:y + 2,
        pz = z - 1<0?0:z - 1, nz = dz>0?z + 1:z, az = z + 2>=depth()?depth() - 1:z + 2;
      const Tfloat
        Ippp = (Tfloat)(*this)(px,py,pz,c), Icpp = (Tfloat)(*this)(x,py,pz,c),
        Inpp = (Tfloat)(*this)(nx,py,pz,c), Iapp = (Tfloat)(*this)(ax,py,pz,c),
        Ipp = Icpp + 0.5f*(dx*(-Ippp + Inpp) + dx*dx*(2*Ippp - 5*Icpp + 4*Inpp - Iapp) +
                           dx*dx*dx*(-Ippp + 3*Icpp - 3*Inpp + Iapp)),
        Ipcp = (Tfloat)(*this)(px,y,pz,c),  Iccp = (Tfloat)(*this)(x, y,pz,c),
        Incp = (Tfloat)(*this)(nx,y,pz,c),  Iacp = (Tfloat)(*this)(ax,y,pz,c),
        Icp = Iccp + 0.5f*(dx*(-Ipcp + Incp) + dx*dx*(2*Ipcp - 5*Iccp + 4*Incp - Iacp) +
                           dx*dx*dx*(-Ipcp + 3*Iccp - 3*Incp + Iacp)),
        Ipnp = (Tfloat)(*this)(px,ny,pz,c), Icnp = (Tfloat)(*this)(x,ny,pz,c),
        Innp = (Tfloat)(*this)(nx,ny,pz,c), Ianp = (Tfloat)(*this)(ax,ny,pz,c),
        Inp = Icnp + 0.5f*(dx*(-Ipnp + Innp) + dx*dx*(2*Ipnp - 5*Icnp + 4*Innp - Ianp) +
                           dx*dx*dx*(-Ipnp + 3*Icnp - 3*Innp + Ianp)),
        Ipap = (Tfloat)(*this)(px,ay,pz,c), Icap = (Tfloat)(*this)(x,ay,pz,c),
        Inap = (Tfloat)(*this)(nx,ay,pz,c), Iaap = (Tfloat)(*this)(ax,ay,pz,c),
        Iap = Icap + 0.5f*(dx*(-Ipap + Inap) + dx*dx*(2*Ipap - 5*Icap + 4*Inap - Iaap) +
                           dx*dx*dx*(-Ipap + 3*Icap - 3*Inap + Iaap)),
        Ip = Icp + 0.5f*(dy*(-Ipp + Inp) + dy*dy*(2*Ipp - 5*Icp + 4*Inp - Iap) +
                         dy*dy*dy*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ippc = (Tfloat)(*this)(px,py,z,c), Icpc = (Tfloat)(*this)(x,py,z,c),
        Inpc = (Tfloat)(*this)(nx,py,z,c), Iapc = (Tfloat)(*this)(ax,py,z,c),
        Ipc = Icpc + 0.5f*(dx*(-Ippc + Inpc) + dx*dx*(2*Ippc - 5*Icpc + 4*Inpc - Iapc) +
                           dx*dx*dx*(-Ippc + 3*Icpc - 3*Inpc + Iapc)),
        Ipcc = (Tfloat)(*this)(px,y,z,c),  Iccc = (Tfloat)(*this)(x, y,z,c),
        Incc = (Tfloat)(*this)(nx,y,z,c),  Iacc = (Tfloat)(*this)(ax,y,z,c),
        Icc = Iccc + 0.5f*(dx*(-Ipcc + Incc) + dx*dx*(2*Ipcc - 5*Iccc + 4*Incc - Iacc) +
                           dx*dx*dx*(-Ipcc + 3*Iccc - 3*Incc + Iacc)),
        Ipnc = (Tfloat)(*this)(px,ny,z,c), Icnc = (Tfloat)(*this)(x,ny,z,c),
        Innc = (Tfloat)(*this)(nx,ny,z,c), Ianc = (Tfloat)(*this)(ax,ny,z,c),
        Inc = Icnc + 0.5f*(dx*(-Ipnc + Innc) + dx*dx*(2*Ipnc - 5*Icnc + 4*Innc - Ianc) +
                           dx*dx*dx*(-Ipnc + 3*Icnc - 3*Innc + Ianc)),
        Ipac = (Tfloat)(*this)(px,ay,z,c), Icac = (Tfloat)(*this)(x,ay,z,c),
        Inac = (Tfloat)(*this)(nx,ay,z,c), Iaac = (Tfloat)(*this)(ax,ay,z,c),
        Iac = Icac + 0.5f*(dx*(-Ipac + Inac) + dx*dx*(2*Ipac - 5*Icac + 4*Inac - Iaac) +
                           dx*dx*dx*(-Ipac + 3*Icac - 3*Inac + Iaac)),
        Ic = Icc + 0.5f*(dy*(-Ipc + Inc) + dy*dy*(2*Ipc - 5*Icc + 4*Inc - Iac) +
                         dy*dy*dy*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ippn = (Tfloat)(*this)(px,py,nz,c), Icpn = (Tfloat)(*this)(x,py,nz,c),
        Inpn = (Tfloat)(*this)(nx,py,nz,c), Iapn = (Tfloat)(*this)(ax,py,nz,c),
        Ipn = Icpn + 0.5f*(dx*(-Ippn + Inpn) + dx*dx*(2*Ippn - 5*Icpn + 4*Inpn - Iapn) +
                           dx*dx*dx*(-Ippn + 3*Icpn - 3*Inpn + Iapn)),
        Ipcn = (Tfloat)(*this)(px,y,nz,c),  Iccn = (Tfloat)(*this)(x, y,nz,c),
        Incn = (Tfloat)(*this)(nx,y,nz,c),  Iacn = (Tfloat)(*this)(ax,y,nz,c),
        Icn = Iccn + 0.5f*(dx*(-Ipcn + Incn) + dx*dx*(2*Ipcn - 5*Iccn + 4*Incn - Iacn) +
                           dx*dx*dx*(-Ipcn + 3*Iccn - 3*Incn + Iacn)),
        Ipnn = (Tfloat)(*this)(px,ny,nz,c), Icnn = (Tfloat)(*this)(x,ny,nz,c),
        Innn = (Tfloat)(*this)(nx,ny,nz,c), Iann = (Tfloat)(*this)(ax,ny,nz,c),
        Inn = Icnn + 0.5f*(dx*(-Ipnn + Innn) + dx*dx*(2*Ipnn - 5*Icnn + 4*Innn - Iann) +
                           dx*dx*dx*(-Ipnn + 3*Icnn - 3*Innn + Iann)),
        Ipan = (Tfloat)(*this)(px,ay,nz,c), Ican = (Tfloat)(*this)(x,ay,nz,c),
        Inan = (Tfloat)(*this)(nx,ay,nz,c), Iaan = (Tfloat)(*this)(ax,ay,nz,c),
        Ian = Ican + 0.5f*(dx*(-Ipan + Inan) + dx*dx*(2*Ipan - 5*Ican + 4*Inan - Iaan) +
                           dx*dx*dx*(-Ipan + 3*Ican - 3*Inan + Iaan)),
        In = Icn + 0.5f*(dy*(-Ipn + Inn) + dy*dy*(2*Ipn - 5*Icn + 4*Inn - Ian) +
                         dy*dy*dy*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ippa = (Tfloat)(*this)(px,py,az,c), Icpa = (Tfloat)(*this)(x,py,az,c),
        Inpa = (Tfloat)(*this)(nx,py,az,c), Iapa = (Tfloat)(*this)(ax,py,az,c),
        Ipa = Icpa + 0.5f*(dx*(-Ippa + Inpa) + dx*dx*(2*Ippa - 5*Icpa + 4*Inpa - Iapa) +
                           dx*dx*dx*(-Ippa + 3*Icpa - 3*Inpa + Iapa)),
        Ipca = (Tfloat)(*this)(px,y,az,c),  Icca = (Tfloat)(*this)(x, y,az,c),
        Inca = (Tfloat)(*this)(nx,y,az,c),  Iaca = (Tfloat)(*this)(ax,y,az,c),
        Ica = Icca + 0.5f*(dx*(-Ipca + Inca) + dx*dx*(2*Ipca - 5*Icca + 4*Inca - Iaca) +
                           dx*dx*dx*(-Ipca + 3*Icca - 3*Inca + Iaca)),
        Ipna = (Tfloat)(*this)(px,ny,az,c), Icna = (Tfloat)(*this)(x,ny,az,c),
        Inna = (Tfloat)(*this)(nx,ny,az,c), Iana = (Tfloat)(*this)(ax,ny,az,c),
        Ina = Icna + 0.5f*(dx*(-Ipna + Inna) + dx*dx*(2*Ipna - 5*Icna + 4*Inna - Iana) +
                           dx*dx*dx*(-Ipna + 3*Icna - 3*Inna + Iana)),
        Ipaa = (Tfloat)(*this)(px,ay,az,c), Icaa = (Tfloat)(*this)(x,ay,az,c),
        Inaa = (Tfloat)(*this)(nx,ay,az,c), Iaaa = (Tfloat)(*this)(ax,ay,az,c),
        Iaa = Icaa + 0.5f*(dx*(-Ipaa + Inaa) + dx*dx*(2*Ipaa - 5*Icaa + 4*Inaa - Iaaa) +
                           dx*dx*dx*(-Ipaa + 3*Icaa - 3*Inaa + Iaaa)),
        Ia = Ica + 0.5f*(dy*(-Ipa + Ina) + dy*dy*(2*Ipa - 5*Ica + 4*Ina - Iaa) +
                         dy*dy*dy*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dz*(-Ip + In) + dz*dz*(2*Ip - 5*Ic + 4*In - Ia) + dz*dz*dz*(-Ip + 3*Ic - 3*In + Ia));
    }

    //! Return clamped pixel value, using cubic interpolation and Neumann boundary conditions for the XYZ-coordinates.
    /**
       Similar to cubic_atXYZ(float,float,float,int) const, except that the return value is clamped to stay in the
       min/max range of the datatype \c T.
    **/
    T cubic_atXYZ_c(const float fx, const float fy, const float fz, const int c) const {
      return cimg::type<T>::cut(cubic_atXYZ(fx,fy,fz,c));
    }

    T _cubic_atXYZ_c(const float fx, const float fy, const float fz, const int c) const {
      return cimg::type<T>::cut(_cubic_atXYZ(fx,fy,fz,c));
    }

    //! Return pixel value, using cubic interpolation and Neumann boundary conditions for the X,Y and Z-coordinates.
    /**
       Similar to cubic_atX(float,int,int,int) const, except that the cubic interpolation and boundary checking
       are achieved both for X,Y and Z-coordinates.
       \note
       - If you know your image instance is \e not empty, you may rather use the slightly faster function
         \c _cubic_atXYZ(float,float,float,int).
    **/
    Tfloat cubic_atXYZ_p(const float fx, const float fy, const float fz, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "cubic_atXYZ_p(): Empty instance.",
                                    cimg_instance);
      return _cubic_atXYZ_p(fx,fy,fz,c);
    }

    Tfloat _cubic_atXYZ_p(const float fx, const float fy, const float fz, const int c=0) const {
      const float
        nfx = cimg::type<float>::is_nan(fx)?0:cimg::mod(fx,_width - 0.5f),
        nfy = cimg::type<float>::is_nan(fy)?0:cimg::mod(fy,_height - 0.5f),
        nfz = cimg::type<float>::is_nan(fz)?0:cimg::mod(fz,_depth - 0.5f);
      const int x = (int)nfx, y = (int)nfy, z = (int)nfz;
      const float dx = nfx - x, dy = nfy - y, dz = nfz - z;
      const int
        px = cimg::mod(x - 1,width()), nx = cimg::mod(x + 1,width()), ax = cimg::mod(x + 2,width()),
        py = cimg::mod(y - 1,height()), ny = cimg::mod(y + 1,height()), ay = cimg::mod(y + 2,height()),
        pz = cimg::mod(z - 1,depth()), nz = cimg::mod(z + 1,depth()), az = cimg::mod(z + 2,depth());
      const Tfloat
        Ippp = (Tfloat)(*this)(px,py,pz,c), Icpp = (Tfloat)(*this)(x,py,pz,c),
        Inpp = (Tfloat)(*this)(nx,py,pz,c), Iapp = (Tfloat)(*this)(ax,py,pz,c),
        Ipp = Icpp + 0.5f*(dx*(-Ippp + Inpp) + dx*dx*(2*Ippp - 5*Icpp + 4*Inpp - Iapp) +
                           dx*dx*dx*(-Ippp + 3*Icpp - 3*Inpp + Iapp)),
        Ipcp = (Tfloat)(*this)(px,y,pz,c),  Iccp = (Tfloat)(*this)(x, y,pz,c),
        Incp = (Tfloat)(*this)(nx,y,pz,c),  Iacp = (Tfloat)(*this)(ax,y,pz,c),
        Icp = Iccp + 0.5f*(dx*(-Ipcp + Incp) + dx*dx*(2*Ipcp - 5*Iccp + 4*Incp - Iacp) +
                           dx*dx*dx*(-Ipcp + 3*Iccp - 3*Incp + Iacp)),
        Ipnp = (Tfloat)(*this)(px,ny,pz,c), Icnp = (Tfloat)(*this)(x,ny,pz,c),
        Innp = (Tfloat)(*this)(nx,ny,pz,c), Ianp = (Tfloat)(*this)(ax,ny,pz,c),
        Inp = Icnp + 0.5f*(dx*(-Ipnp + Innp) + dx*dx*(2*Ipnp - 5*Icnp + 4*Innp - Ianp) +
                           dx*dx*dx*(-Ipnp + 3*Icnp - 3*Innp + Ianp)),
        Ipap = (Tfloat)(*this)(px,ay,pz,c), Icap = (Tfloat)(*this)(x,ay,pz,c),
        Inap = (Tfloat)(*this)(nx,ay,pz,c), Iaap = (Tfloat)(*this)(ax,ay,pz,c),
        Iap = Icap + 0.5f*(dx*(-Ipap + Inap) + dx*dx*(2*Ipap - 5*Icap + 4*Inap - Iaap) +
                           dx*dx*dx*(-Ipap + 3*Icap - 3*Inap + Iaap)),
        Ip = Icp + 0.5f*(dy*(-Ipp + Inp) + dy*dy*(2*Ipp - 5*Icp + 4*Inp - Iap) +
                         dy*dy*dy*(-Ipp + 3*Icp - 3*Inp + Iap)),
        Ippc = (Tfloat)(*this)(px,py,z,c), Icpc = (Tfloat)(*this)(x,py,z,c),
        Inpc = (Tfloat)(*this)(nx,py,z,c), Iapc = (Tfloat)(*this)(ax,py,z,c),
        Ipc = Icpc + 0.5f*(dx*(-Ippc + Inpc) + dx*dx*(2*Ippc - 5*Icpc + 4*Inpc - Iapc) +
                           dx*dx*dx*(-Ippc + 3*Icpc - 3*Inpc + Iapc)),
        Ipcc = (Tfloat)(*this)(px,y,z,c),  Iccc = (Tfloat)(*this)(x, y,z,c),
        Incc = (Tfloat)(*this)(nx,y,z,c),  Iacc = (Tfloat)(*this)(ax,y,z,c),
        Icc = Iccc + 0.5f*(dx*(-Ipcc + Incc) + dx*dx*(2*Ipcc - 5*Iccc + 4*Incc - Iacc) +
                           dx*dx*dx*(-Ipcc + 3*Iccc - 3*Incc + Iacc)),
        Ipnc = (Tfloat)(*this)(px,ny,z,c), Icnc = (Tfloat)(*this)(x,ny,z,c),
        Innc = (Tfloat)(*this)(nx,ny,z,c), Ianc = (Tfloat)(*this)(ax,ny,z,c),
        Inc = Icnc + 0.5f*(dx*(-Ipnc + Innc) + dx*dx*(2*Ipnc - 5*Icnc + 4*Innc - Ianc) +
                           dx*dx*dx*(-Ipnc + 3*Icnc - 3*Innc + Ianc)),
        Ipac = (Tfloat)(*this)(px,ay,z,c), Icac = (Tfloat)(*this)(x,ay,z,c),
        Inac = (Tfloat)(*this)(nx,ay,z,c), Iaac = (Tfloat)(*this)(ax,ay,z,c),
        Iac = Icac + 0.5f*(dx*(-Ipac + Inac) + dx*dx*(2*Ipac - 5*Icac + 4*Inac - Iaac) +
                           dx*dx*dx*(-Ipac + 3*Icac - 3*Inac + Iaac)),
        Ic = Icc + 0.5f*(dy*(-Ipc + Inc) + dy*dy*(2*Ipc - 5*Icc + 4*Inc - Iac) +
                         dy*dy*dy*(-Ipc + 3*Icc - 3*Inc + Iac)),
        Ippn = (Tfloat)(*this)(px,py,nz,c), Icpn = (Tfloat)(*this)(x,py,nz,c),
        Inpn = (Tfloat)(*this)(nx,py,nz,c), Iapn = (Tfloat)(*this)(ax,py,nz,c),
        Ipn = Icpn + 0.5f*(dx*(-Ippn + Inpn) + dx*dx*(2*Ippn - 5*Icpn + 4*Inpn - Iapn) +
                           dx*dx*dx*(-Ippn + 3*Icpn - 3*Inpn + Iapn)),
        Ipcn = (Tfloat)(*this)(px,y,nz,c),  Iccn = (Tfloat)(*this)(x, y,nz,c),
        Incn = (Tfloat)(*this)(nx,y,nz,c),  Iacn = (Tfloat)(*this)(ax,y,nz,c),
        Icn = Iccn + 0.5f*(dx*(-Ipcn + Incn) + dx*dx*(2*Ipcn - 5*Iccn + 4*Incn - Iacn) +
                           dx*dx*dx*(-Ipcn + 3*Iccn - 3*Incn + Iacn)),
        Ipnn = (Tfloat)(*this)(px,ny,nz,c), Icnn = (Tfloat)(*this)(x,ny,nz,c),
        Innn = (Tfloat)(*this)(nx,ny,nz,c), Iann = (Tfloat)(*this)(ax,ny,nz,c),
        Inn = Icnn + 0.5f*(dx*(-Ipnn + Innn) + dx*dx*(2*Ipnn - 5*Icnn + 4*Innn - Iann) +
                           dx*dx*dx*(-Ipnn + 3*Icnn - 3*Innn + Iann)),
        Ipan = (Tfloat)(*this)(px,ay,nz,c), Ican = (Tfloat)(*this)(x,ay,nz,c),
        Inan = (Tfloat)(*this)(nx,ay,nz,c), Iaan = (Tfloat)(*this)(ax,ay,nz,c),
        Ian = Ican + 0.5f*(dx*(-Ipan + Inan) + dx*dx*(2*Ipan - 5*Ican + 4*Inan - Iaan) +
                           dx*dx*dx*(-Ipan + 3*Ican - 3*Inan + Iaan)),
        In = Icn + 0.5f*(dy*(-Ipn + Inn) + dy*dy*(2*Ipn - 5*Icn + 4*Inn - Ian) +
                         dy*dy*dy*(-Ipn + 3*Icn - 3*Inn + Ian)),
        Ippa = (Tfloat)(*this)(px,py,az,c), Icpa = (Tfloat)(*this)(x,py,az,c),
        Inpa = (Tfloat)(*this)(nx,py,az,c), Iapa = (Tfloat)(*this)(ax,py,az,c),
        Ipa = Icpa + 0.5f*(dx*(-Ippa + Inpa) + dx*dx*(2*Ippa - 5*Icpa + 4*Inpa - Iapa) +
                           dx*dx*dx*(-Ippa + 3*Icpa - 3*Inpa + Iapa)),
        Ipca = (Tfloat)(*this)(px,y,az,c),  Icca = (Tfloat)(*this)(x, y,az,c),
        Inca = (Tfloat)(*this)(nx,y,az,c),  Iaca = (Tfloat)(*this)(ax,y,az,c),
        Ica = Icca + 0.5f*(dx*(-Ipca + Inca) + dx*dx*(2*Ipca - 5*Icca + 4*Inca - Iaca) +
                           dx*dx*dx*(-Ipca + 3*Icca - 3*Inca + Iaca)),
        Ipna = (Tfloat)(*this)(px,ny,az,c), Icna = (Tfloat)(*this)(x,ny,az,c),
        Inna = (Tfloat)(*this)(nx,ny,az,c), Iana = (Tfloat)(*this)(ax,ny,az,c),
        Ina = Icna + 0.5f*(dx*(-Ipna + Inna) + dx*dx*(2*Ipna - 5*Icna + 4*Inna - Iana) +
                           dx*dx*dx*(-Ipna + 3*Icna - 3*Inna + Iana)),
        Ipaa = (Tfloat)(*this)(px,ay,az,c), Icaa = (Tfloat)(*this)(x,ay,az,c),
        Inaa = (Tfloat)(*this)(nx,ay,az,c), Iaaa = (Tfloat)(*this)(ax,ay,az,c),
        Iaa = Icaa + 0.5f*(dx*(-Ipaa + Inaa) + dx*dx*(2*Ipaa - 5*Icaa + 4*Inaa - Iaaa) +
                           dx*dx*dx*(-Ipaa + 3*Icaa - 3*Inaa + Iaaa)),
        Ia = Ica + 0.5f*(dy*(-Ipa + Ina) + dy*dy*(2*Ipa - 5*Ica + 4*Ina - Iaa) +
                         dy*dy*dy*(-Ipa + 3*Ica - 3*Ina + Iaa));
      return Ic + 0.5f*(dz*(-Ip + In) + dz*dz*(2*Ip - 5*Ic + 4*In - Ia) + dz*dz*dz*(-Ip + 3*Ic - 3*In + Ia));
    }

    T cubic_atXYZ_pc(const float fx, const float fy, const float fz, const int c) const {
      return cimg::type<T>::cut(cubic_atXYZ_p(fx,fy,fz,c));
    }

    T _cubic_atXYZ_pc(const float fx, const float fy, const float fz, const int c) const {
      return cimg::type<T>::cut(_cubic_atXYZ_p(fx,fy,fz,c));
    }

    //! Set pixel value, using linear interpolation for the X-coordinates.
    /**
       Set pixel value at specified coordinates (\c fx,\c y,\c z,\c c) in the image instance, in a way that
       the value is spread amongst several neighbors if the pixel coordinates are float-valued.
       \param value Pixel value to set.
       \param fx X-coordinate of the pixel value (float-valued).
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param is_added Indicates whether the pixel value is added to (\c true), or simply replace (\c false)
         the current image pixel(s).
       \return A reference to the current image instance.
       \note
       - Calling this function with out-of-bounds coordinates does nothing.
    **/
    CImg<T>& set_linear_atX(const T& value, const float fx, const int y=0, const int z=0, const int c=0,
                            const bool is_added=false) {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1;
      const float
        dx = fx - x;
      if (y>=0 && y<height() && z>=0 && z<depth() && c>=0 && c<spectrum()) {
        if (x>=0 && x<width()) {
          const float w1 = 1 - dx, w2 = is_added?1:(1 - w1);
          (*this)(x,y,z,c) = (T)(w1*value + w2*(*this)(x,y,z,c));
        }
        if (nx>=0 && nx<width()) {
          const float w1 = dx, w2 = is_added?1:(1 - w1);
          (*this)(nx,y,z,c) = (T)(w1*value + w2*(*this)(nx,y,z,c));
        }
      }
      return *this;
    }

    //! Set pixel value, using linear interpolation for the X and Y-coordinates.
    /**
       Similar to set_linear_atX(const T&,float,int,int,int,bool), except that the linear interpolation
       is achieved both for X and Y-coordinates.
    **/
    CImg<T>& set_linear_atXY(const T& value, const float fx, const float fy=0, const int z=0, const int c=0,
                             const bool is_added=false) {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1,
        y = (int)fy - (fy>=0?0:1), ny = y + 1;
      const float
        dx = fx - x,
        dy = fy - y;
      if (z>=0 && z<depth() && c>=0 && c<spectrum()) {
        if (y>=0 && y<height()) {
          if (x>=0 && x<width()) {
            const float w1 = (1 - dx)*(1 - dy), w2 = is_added?1:(1 - w1);
            (*this)(x,y,z,c) = (T)(w1*value + w2*(*this)(x,y,z,c));
          }
          if (nx>=0 && nx<width()) {
            const float w1 = dx*(1 - dy), w2 = is_added?1:(1 - w1);
            (*this)(nx,y,z,c) = (T)(w1*value + w2*(*this)(nx,y,z,c));
          }
        }
        if (ny>=0 && ny<height()) {
          if (x>=0 && x<width()) {
            const float w1 = (1 - dx)*dy, w2 = is_added?1:(1 - w1);
            (*this)(x,ny,z,c) = (T)(w1*value + w2*(*this)(x,ny,z,c));
          }
          if (nx>=0 && nx<width()) {
            const float w1 = dx*dy, w2 = is_added?1:(1 - w1);
            (*this)(nx,ny,z,c) = (T)(w1*value + w2*(*this)(nx,ny,z,c));
          }
        }
      }
      return *this;
    }

    //! Set pixel value, using linear interpolation for the X,Y and Z-coordinates.
    /**
       Similar to set_linear_atXY(const T&,float,float,int,int,bool), except that the linear interpolation
       is achieved both for X,Y and Z-coordinates.
    **/
    CImg<T>& set_linear_atXYZ(const T& value, const float fx, const float fy=0, const float fz=0, const int c=0,
                              const bool is_added=false) {
      const int
        x = (int)fx - (fx>=0?0:1), nx = x + 1,
        y = (int)fy - (fy>=0?0:1), ny = y + 1,
        z = (int)fz - (fz>=0?0:1), nz = z + 1;
      const float
        dx = fx - x,
        dy = fy - y,
        dz = fz - z;
      if (c>=0 && c<spectrum()) {
        if (z>=0 && z<depth()) {
          if (y>=0 && y<height()) {
            if (x>=0 && x<width()) {
              const float w1 = (1 - dx)*(1 - dy)*(1 - dz), w2 = is_added?1:(1 - w1);
              (*this)(x,y,z,c) = (T)(w1*value + w2*(*this)(x,y,z,c));
            }
            if (nx>=0 && nx<width()) {
              const float w1 = dx*(1 - dy)*(1 - dz), w2 = is_added?1:(1 - w1);
              (*this)(nx,y,z,c) = (T)(w1*value + w2*(*this)(nx,y,z,c));
            }
          }
          if (ny>=0 && ny<height()) {
            if (x>=0 && x<width()) {
              const float w1 = (1 - dx)*dy*(1 - dz), w2 = is_added?1:(1 - w1);
              (*this)(x,ny,z,c) = (T)(w1*value + w2*(*this)(x,ny,z,c));
            }
            if (nx>=0 && nx<width()) {
              const float w1 = dx*dy*(1 - dz), w2 = is_added?1:(1 - w1);
              (*this)(nx,ny,z,c) = (T)(w1*value + w2*(*this)(nx,ny,z,c));
            }
          }
        }
        if (nz>=0 && nz<depth()) {
          if (y>=0 && y<height()) {
            if (x>=0 && x<width()) {
              const float w1 = (1 - dx)*(1 - dy)*dz, w2 = is_added?1:(1 - w1);
              (*this)(x,y,nz,c) = (T)(w1*value + w2*(*this)(x,y,nz,c));
            }
            if (nx>=0 && nx<width()) {
              const float w1 = dx*(1 - dy)*dz, w2 = is_added?1:(1 - w1);
              (*this)(nx,y,nz,c) = (T)(w1*value + w2*(*this)(nx,y,nz,c));
            }
          }
          if (ny>=0 && ny<height()) {
            if (x>=0 && x<width()) {
              const float w1 = (1 - dx)*dy*dz, w2 = is_added?1:(1 - w1);
              (*this)(x,ny,nz,c) = (T)(w1*value + w2*(*this)(x,ny,nz,c));
            }
            if (nx>=0 && nx<width()) {
              const float w1 = dx*dy*dz, w2 = is_added?1:(1 - w1);
              (*this)(nx,ny,nz,c) = (T)(w1*value + w2*(*this)(nx,ny,nz,c));
            }
          }
        }
      }
      return *this;
    }

    //! Return a C-string containing a list of all values of the image instance.
    /**
       Return a new \c CImg<char> image whose buffer data() is a \c char* string describing the list of all pixel values
       of the image instance (written in base 10), separated by specified \c separator character.
       \param separator A \c char character which specifies the separator between values in the returned C-string.
       \param max_size Maximum size of the returned image (or \c 0 if no limits are set).
       \param format For float/double-values, tell the printf format used to generate the text representation
         of the numbers (or \c 0 for default representation).
       \note
       - The returned image is never empty.
       - For an empty image instance, the returned string is <tt>""</tt>.
       - If \c max_size is equal to \c 0, there are no limits on the size of the returned string.
       - Otherwise, if the maximum number of string characters is exceeded, the value string is cut off
         and terminated by character \c '\0'. In that case, the returned image size is <tt>max_size + 1</tt>.
    **/
    CImg<charT> value_string(const char separator=',', const unsigned int max_size=0,
                             const char *const format=0) const {
      if (is_empty() || max_size==1) return CImg<charT>(1,1,1,1,0);
      CImgList<charT> items;
      CImg<charT> s_item(256); *s_item = 0;
      const T *ptrs = _data;
      unsigned int string_size = 0;
      const char *const _format = format?format:cimg::type<T>::format();
      for (ulongT off = 0, siz = size(); off<siz && (!max_size || string_size<max_size); ++off) {
        const unsigned int printed_size = 1U + cimg_snprintf(s_item,s_item._width,_format,
                                                             cimg::type<T>::format(*(ptrs++)));
        CImg<charT> item(s_item._data,std::min(printed_size,s_item._width));
        item[printed_size - 1] = separator;
        item.move_to(items);
        if (max_size) string_size+=printed_size;
      }
      CImg<charT> res;
      (items>'x').move_to(res);
      if (max_size && res._width>=max_size) res.crop(0,max_size - 1);
      res.back() = 0;
      return res;
    }

    //@}
    //-------------------------------------
    //
    //! \name Instance Checking
    //@{
    //-------------------------------------

    //! Test shared state of the pixel buffer.
    /**
       Return \c true if image instance has a shared memory buffer, and \c false otherwise.
       \note
       - A shared image does not own its pixel buffer data() and will not deallocate it on destruction.
       - Most of the time, a \c CImg<T> image instance will \e not be shared.
       - A shared image can only be obtained by a limited set of constructors and functions (see list below).
    **/
    bool is_shared() const {
      return _is_shared;
    }

    //! Test if image instance is empty.
    /**
       Return \c true if image instance is empty, i.e. does \e not contain any pixel values, has dimensions
       \c 0 x \c 0 x \c 0 x \c 0 and a pixel buffer pointer set to \c 0 (null pointer), and \c false otherwise.
    **/
    bool is_empty() const {
      return !(_data && _width && _height && _depth && _spectrum);
    }

    //! Test if image instance contains a 'inf' value.
    /**
       Return \c true if image instance contains a 'inf' value, and \c false otherwise.
    **/
    bool is_inf() const {
      if (cimg::type<T>::is_float()) cimg_for(*this,p,T) if (cimg::type<T>::is_inf((double)*p)) return true;
      return false;
    }

    //! Test if image instance contains a NaN value.
    /**
       Return \c true if image instance contains a NaN value, and \c false otherwise.
    **/
    bool is_nan() const {
      if (cimg::type<T>::is_float()) cimg_for(*this,p,T) if (cimg::type<T>::is_nan((double)*p)) return true;
      return false;
    }

    //! Test if image width is equal to specified value.
    bool is_sameX(const unsigned int size_x) const {
      return _width==size_x;
    }

    //! Test if image width is equal to specified value.
    template<typename t>
    bool is_sameX(const CImg<t>& img) const {
      return is_sameX(img._width);
    }

    //! Test if image width is equal to specified value.
    bool is_sameX(const CImgDisplay& disp) const {
      return is_sameX(disp._width);
    }

    //! Test if image height is equal to specified value.
    bool is_sameY(const unsigned int size_y) const {
      return _height==size_y;
    }

    //! Test if image height is equal to specified value.
    template<typename t>
    bool is_sameY(const CImg<t>& img) const {
      return is_sameY(img._height);
    }

    //! Test if image height is equal to specified value.
    bool is_sameY(const CImgDisplay& disp) const {
      return is_sameY(disp._height);
    }

    //! Test if image depth is equal to specified value.
    bool is_sameZ(const unsigned int size_z) const {
      return _depth==size_z;
    }

    //! Test if image depth is equal to specified value.
    template<typename t>
    bool is_sameZ(const CImg<t>& img) const {
      return is_sameZ(img._depth);
    }

    //! Test if image spectrum is equal to specified value.
    bool is_sameC(const unsigned int size_c) const {
      return _spectrum==size_c;
    }

    //! Test if image spectrum is equal to specified value.
    template<typename t>
    bool is_sameC(const CImg<t>& img) const {
      return is_sameC(img._spectrum);
    }

    //! Test if image width and height are equal to specified values.
    /**
       Test if is_sameX(unsigned int) const and is_sameY(unsigned int) const are both verified.
    **/
    bool is_sameXY(const unsigned int size_x, const unsigned int size_y) const {
      return _width==size_x && _height==size_y;
    }

    //! Test if image width and height are the same as those of another image.
    /**
       Test if is_sameX(const CImg<t>&) const and is_sameY(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXY(const CImg<t>& img) const {
      return is_sameXY(img._width,img._height);
    }

    //! Test if image width and height are the same as that of an existing display window.
    /**
       Test if is_sameX(const CImgDisplay&) const and is_sameY(const CImgDisplay&) const are both verified.
    **/
    bool is_sameXY(const CImgDisplay& disp) const {
      return is_sameXY(disp._width,disp._height);
    }

    //! Test if image width and depth are equal to specified values.
    /**
       Test if is_sameX(unsigned int) const and is_sameZ(unsigned int) const are both verified.
    **/
    bool is_sameXZ(const unsigned int size_x, const unsigned int size_z) const {
      return _width==size_x && _depth==size_z;
    }

    //! Test if image width and depth are the same as those of another image.
    /**
       Test if is_sameX(const CImg<t>&) const and is_sameZ(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXZ(const CImg<t>& img) const {
      return is_sameXZ(img._width,img._depth);
    }

    //! Test if image width and spectrum are equal to specified values.
    /**
       Test if is_sameX(unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameXC(const unsigned int size_x, const unsigned int size_c) const {
      return _width==size_x && _spectrum==size_c;
    }

    //! Test if image width and spectrum are the same as those of another image.
    /**
       Test if is_sameX(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXC(const CImg<t>& img) const {
      return is_sameXC(img._width,img._spectrum);
    }

    //! Test if image height and depth are equal to specified values.
    /**
       Test if is_sameY(unsigned int) const and is_sameZ(unsigned int) const are both verified.
    **/
    bool is_sameYZ(const unsigned int size_y, const unsigned int size_z) const {
      return _height==size_y && _depth==size_z;
    }

    //! Test if image height and depth are the same as those of another image.
    /**
       Test if is_sameY(const CImg<t>&) const and is_sameZ(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameYZ(const CImg<t>& img) const {
      return is_sameYZ(img._height,img._depth);
    }

    //! Test if image height and spectrum are equal to specified values.
    /**
       Test if is_sameY(unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameYC(const unsigned int size_y, const unsigned int size_c) const {
      return _height==size_y && _spectrum==size_c;
    }

    //! Test if image height and spectrum are the same as those of another image.
    /**
       Test if is_sameY(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameYC(const CImg<t>& img) const {
      return is_sameYC(img._height,img._spectrum);
    }

    //! Test if image depth and spectrum are equal to specified values.
    /**
       Test if is_sameZ(unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameZC(const unsigned int size_z, const unsigned int size_c) const {
      return _depth==size_z && _spectrum==size_c;
    }

    //! Test if image depth and spectrum are the same as those of another image.
    /**
       Test if is_sameZ(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameZC(const CImg<t>& img) const {
      return is_sameZC(img._depth,img._spectrum);
    }

    //! Test if image width, height and depth are equal to specified values.
    /**
       Test if is_sameXY(unsigned int,unsigned int) const and is_sameZ(unsigned int) const are both verified.
    **/
    bool is_sameXYZ(const unsigned int size_x, const unsigned int size_y, const unsigned int size_z) const {
      return is_sameXY(size_x,size_y) && _depth==size_z;
    }

    //! Test if image width, height and depth are the same as those of another image.
    /**
       Test if is_sameXY(const CImg<t>&) const and is_sameZ(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXYZ(const CImg<t>& img) const {
      return is_sameXYZ(img._width,img._height,img._depth);
    }

    //! Test if image width, height and spectrum are equal to specified values.
    /**
       Test if is_sameXY(unsigned int,unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameXYC(const unsigned int size_x, const unsigned int size_y, const unsigned int size_c) const {
      return is_sameXY(size_x,size_y) && _spectrum==size_c;
    }

    //! Test if image width, height and spectrum are the same as those of another image.
    /**
       Test if is_sameXY(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXYC(const CImg<t>& img) const {
      return is_sameXYC(img._width,img._height,img._spectrum);
    }

    //! Test if image width, depth and spectrum are equal to specified values.
    /**
       Test if is_sameXZ(unsigned int,unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameXZC(const unsigned int size_x, const unsigned int size_z, const unsigned int size_c) const {
      return is_sameXZ(size_x,size_z) && _spectrum==size_c;
    }

    //! Test if image width, depth and spectrum are the same as those of another image.
    /**
       Test if is_sameXZ(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXZC(const CImg<t>& img) const {
      return is_sameXZC(img._width,img._depth,img._spectrum);
    }

    //! Test if image height, depth and spectrum are equal to specified values.
    /**
       Test if is_sameYZ(unsigned int,unsigned int) const and is_sameC(unsigned int) const are both verified.
    **/
    bool is_sameYZC(const unsigned int size_y, const unsigned int size_z, const unsigned int size_c) const {
      return is_sameYZ(size_y,size_z) && _spectrum==size_c;
    }

    //! Test if image height, depth and spectrum are the same as those of another image.
    /**
       Test if is_sameYZ(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameYZC(const CImg<t>& img) const {
      return is_sameYZC(img._height,img._depth,img._spectrum);
    }

    //! Test if image width, height, depth and spectrum are equal to specified values.
    /**
       Test if is_sameXYZ(unsigned int,unsigned int,unsigned int) const and is_sameC(unsigned int) const are both
       verified.
    **/
    bool is_sameXYZC(const unsigned int size_x, const unsigned int size_y,
                     const unsigned int size_z, const unsigned int size_c) const {
      return is_sameXYZ(size_x,size_y,size_z) && _spectrum==size_c;
    }

    //! Test if image width, height, depth and spectrum are the same as those of another image.
    /**
       Test if is_sameXYZ(const CImg<t>&) const and is_sameC(const CImg<t>&) const are both verified.
    **/
    template<typename t>
    bool is_sameXYZC(const CImg<t>& img) const {
      return is_sameXYZC(img._width,img._height,img._depth,img._spectrum);
    }

    //! Test if specified coordinates are inside image bounds.
    /**
       Return \c true if pixel located at (\c x,\c y,\c z,\c c) is inside bounds of the image instance,
       and \c false otherwise.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note
       - Return \c true only if all these conditions are verified:
         - The image instance is \e not empty.
         - <tt>0<=x<=\ref width() - 1</tt>.
         - <tt>0<=y<=\ref height() - 1</tt>.
         - <tt>0<=z<=\ref depth() - 1</tt>.
         - <tt>0<=c<=\ref spectrum() - 1</tt>.
    **/
    bool containsXYZC(const int x, const int y=0, const int z=0, const int c=0) const {
      return x>=0 && x<width() && y>=0 && y<height() && z>=0 && z<depth() && c>=0 && c<spectrum();
    }

    //! Test if pixel value is inside image bounds and get its X,Y,Z and C-coordinates.
    /**
       Return \c true if specified reference refers to a pixel value inside bounds of the image instance,
       and \c false otherwise.
       \param pixel Reference to pixel value to test.
       \param[out] x X-coordinate of the pixel value, if test succeeds.
       \param[out] y Y-coordinate of the pixel value, if test succeeds.
       \param[out] z Z-coordinate of the pixel value, if test succeeds.
       \param[out] c C-coordinate of the pixel value, if test succeeds.
       \note
       - Useful to convert an offset to a buffer value into pixel value coordinates:
       \code
       const CImg<float> img(100,100,1,3); // Construct a 100x100 RGB color image
       const unsigned long offset = 1249; // Offset to the pixel (49,12,0,0)
       unsigned int x,y,z,c;
       if (img.contains(img[offset],x,y,z,c)) { // Convert offset to (x,y,z,c) coordinates
         std::printf("Offset %u refers to pixel located at (%u,%u,%u,%u).\n",
                     offset,x,y,z,c);
       }
       \endcode
    **/
    template<typename t>
    bool contains(const T& pixel, t& x, t& y, t& z, t& c) const {
      const ulongT wh = (ulongT)_width*_height, whd = wh*_depth, siz = whd*_spectrum;
      const T *const ppixel = &pixel;
      if (is_empty() || ppixel<_data || ppixel>=_data + siz) return false;
      ulongT off = (ulongT)(ppixel - _data);
      const ulongT nc = off/whd;
      off%=whd;
      const ulongT nz = off/wh;
      off%=wh;
      const ulongT ny = off/_width, nx = off%_width;
      x = (t)nx; y = (t)ny; z = (t)nz; c = (t)nc;
      return true;
    }

    //! Test if pixel value is inside image bounds and get its X,Y and Z-coordinates.
    /**
       Similar to contains(const T&,t&,t&,t&,t&) const, except that only the X,Y and Z-coordinates are set.
    **/
    template<typename t>
    bool contains(const T& pixel, t& x, t& y, t& z) const {
      const ulongT wh = (ulongT)_width*_height, whd = wh*_depth, siz = whd*_spectrum;
      const T *const ppixel = &pixel;
      if (is_empty() || ppixel<_data || ppixel>=_data + siz) return false;
      ulongT off = ((ulongT)(ppixel - _data))%whd;
      const ulongT nz = off/wh;
      off%=wh;
      const ulongT ny = off/_width, nx = off%_width;
      x = (t)nx; y = (t)ny; z = (t)nz;
      return true;
    }

    //! Test if pixel value is inside image bounds and get its X and Y-coordinates.
    /**
       Similar to contains(const T&,t&,t&,t&,t&) const, except that only the X and Y-coordinates are set.
    **/
    template<typename t>
    bool contains(const T& pixel, t& x, t& y) const {
      const ulongT wh = (ulongT)_width*_height, siz = wh*_depth*_spectrum;
      const T *const ppixel = &pixel;
      if (is_empty() || ppixel<_data || ppixel>=_data + siz) return false;
      ulongT off = ((unsigned int)(ppixel - _data))%wh;
      const ulongT ny = off/_width, nx = off%_width;
      x = (t)nx; y = (t)ny;
      return true;
    }

    //! Test if pixel value is inside image bounds and get its X-coordinate.
    /**
       Similar to contains(const T&,t&,t&,t&,t&) const, except that only the X-coordinate is set.
    **/
    template<typename t>
    bool contains(const T& pixel, t& x) const {
      const T *const ppixel = &pixel;
      if (is_empty() || ppixel<_data || ppixel>=_data + size()) return false;
      x = (t)(((ulongT)(ppixel - _data))%_width);
      return true;
    }

    //! Test if pixel value is inside image bounds.
    /**
       Similar to contains(const T&,t&,t&,t&,t&) const, except that no pixel coordinates are set.
    **/
    bool contains(const T& pixel) const {
      const T *const ppixel = &pixel;
      return !is_empty() && ppixel>=_data && ppixel<_data + size();
    }

    //! Test if pixel buffers of instance and input images overlap.
    /**
       Return \c true if pixel buffers attached to image instance and input image \c img overlap,
       and \c false otherwise.
       \param img Input image to compare with.
       \note
       - Buffer overlapping may happen when manipulating \e shared images.
       - If two image buffers overlap, operating on one of the image will probably modify the other one.
       - Most of the time, \c CImg<T> instances are \e non-shared and do not overlap between each others.
       \par Example
       \code
       const CImg<float>
         img1("reference.jpg"), // Load RGB-color image
         img2 = img1.get_shared_channel(1); // Get shared version of the green channel
       if (img1.is_overlapped(img2)) { // Test succeeds, 'img1' and 'img2' overlaps
         std::printf("Buffers overlap!\n");
       }
       \endcode
    **/
    template<typename t>
    bool is_overlapped(const CImg<t>& img) const {
      const ulongT csiz = size(), isiz = img.size();
      return !((void*)(_data + csiz)<=(void*)img._data || (void*)_data>=(void*)(img._data + isiz));
    }

    //! Test if the set {\c *this,\c primitives,\c colors,\c opacities} defines a valid 3D object.
    /**
       Return \c true if the 3D object represented by the set {\c *this,\c primitives,\c colors,\c opacities} is valid,
         and \c false otherwise. The vertex coordinates are defined by the instance image.
       \param primitives List of primitives of the 3D object.
       \param colors List of colors of the 3D object.
       \param opacities List (or image) of opacities of the 3D object.
       \param full_check Indicates whether full checking of the 3D object must be performed.
       \param[out] error_message C-string to contain the error message, if the test does not succeed
                   (at least 256 bytes).
       \note
       - Set \c full_checking to \c false to speed-up the 3D object checking. In this case, only the size of
         each 3D object component is checked.
       - Size of the string \c error_message should be at least 128-bytes long, to be able to contain the error message.
    **/
    template<typename tp, typename tc, typename to>
    bool is_object3d(const CImgList<tp>& primitives,
                     const CImgList<tc>& colors,
                     const to& opacities,
                     const bool full_check=true,
                     char *const error_message=0) const {
      if (error_message) *error_message = 0;

      // Check the consistency for the particular case of an empty 3D object.
      if (is_empty()) {
        if (primitives || colors || opacities) {
          if (error_message) cimg_snprintf(error_message,256,
                                          "3D object (%u,%u) defines no vertices but %u primitives, "
                                          "%u colors and %lu opacities",
                                          _width,primitives._width,primitives._width,
                                          colors._width,(unsigned long)opacities.size());
          return false;
        }
        return true;
      }

      // Check the consistency of vertices.
      if (_height!=3 || _depth>1 || _spectrum>1) { // Check vertices dimensions
        if (error_message) cimg_snprintf(error_message,256,
                                        "3D object (%u,%u) has invalid vertex dimensions (%u,%u,%u,%u)",
                                        _width,primitives._width,_width,_height,_depth,_spectrum);
        return false;
      }
      if (colors._width>primitives._width + 1) {
        if (error_message) cimg_snprintf(error_message,256,
                                        "3D object (%u,%u) defines %u colors",
                                        _width,primitives._width,colors._width);
        return false;
      }
      if (opacities.size()>primitives._width) {
        if (error_message) cimg_snprintf(error_message,256,
                                        "3D object (%u,%u) defines %lu opacities",
                                        _width,primitives._width,(unsigned long)opacities.size());
        return false;
      }
      if (!full_check) return true;

      // Check the consistency of primitives.
      cimglist_for(primitives,l) {
        const CImg<tp>& primitive = primitives[l];
        const unsigned int psiz = (unsigned int)primitive.size();
        switch (psiz) {
        case 1 : { // Point
          const unsigned int i0 = (unsigned int)primitive(0);
          if (i0>=_width) {
            if (error_message) cimg_snprintf(error_message,256,
                                            "3D object (%u,%u) refers to invalid vertex index %u in "
                                            "point primitive [%u]",
                                            _width,primitives._width,i0,l);
            return false;
          }
        } break;
        case 5 : { // Sphere
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1);
          if (i0>=_width || i1>=_width) {
            if (error_message) cimg_snprintf(error_message,256,
                                            "3D object (%u,%u) refers to invalid vertex indices (%u,%u) in "
                                            "sphere primitive [%u]",
                                            _width,primitives._width,i0,i1,l);
            return false;
          }
        } break;
        case 2 : case 6 : { // Segment
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1);
          if (i0>=_width || i1>=_width) {
            if (error_message) cimg_snprintf(error_message,256,
                                            "3D object (%u,%u) refers to invalid vertex indices (%u,%u) in "
                                            "segment primitive [%u]",
                                            _width,primitives._width,i0,i1,l);
            return false;
          }
        } break;
        case 3 : case 9 : { // Triangle
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1),
            i2 = (unsigned int)primitive(2);
          if (i0>=_width || i1>=_width || i2>=_width) {
            if (error_message) cimg_snprintf(error_message,256,
                                            "3D object (%u,%u) refers to invalid vertex indices (%u,%u,%u) in "
                                            "triangle primitive [%u]",
                                            _width,primitives._width,i0,i1,i2,l);
            return false;
          }
        } break;
        case 4 : case 12 : { // Quadrangle
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1),
            i2 = (unsigned int)primitive(2),
            i3 = (unsigned int)primitive(3);
          if (i0>=_width || i1>=_width || i2>=_width || i3>=_width) {
            if (error_message) cimg_snprintf(error_message,256,
                                            "3D object (%u,%u) refers to invalid vertex indices (%u,%u,%u,%u) in "
                                            "quadrangle primitive [%u]",
                                            _width,primitives._width,i0,i1,i2,i3,l);
            return false;
          }
        } break;
        default :
          if (error_message) cimg_snprintf(error_message,256,
                                          "3D object (%u,%u) defines an invalid primitive [%u] of size %u",
                                          _width,primitives._width,l,(unsigned int)psiz);
          return false;
        }
      }

      // Check the consistency of colors.
      cimglist_for(colors,c) {
        const CImg<tc>& color = colors[c];
        if (!color) {
          if (error_message) cimg_snprintf(error_message,256,
                                          "3D object (%u,%u) defines no color for primitive [%u]",
                                          _width,primitives._width,c);
          return false;
        }
      }

      // Check the consistency of light texture.
      if (colors._width>primitives._width) {
        const CImg<tc> &light = colors.back();
        if (!light || light._depth>1) {
          if (error_message) cimg_snprintf(error_message,256,
                                          "3D object (%u,%u) defines an invalid light texture (%u,%u,%u,%u)",
                                          _width,primitives._width,light._width,
                                          light._height,light._depth,light._spectrum);
          return false;
        }
      }

      return true;
    }

    //! Test if image instance represents a valid serialization of a 3D object.
    /**
       Return \c true if the image instance represents a valid serialization of a 3D object, and \c false otherwise.
       \param full_check Indicates whether full checking of the instance must be performed.
       \param[out] error_message C-string to contain the error message, if the test does not succeed.
       \note
       - Set \c full_check to \c false to speed-up the 3D object checking. In this case, only the size of
         each 3D object component is checked.
       - Size of the string \c error_message should be at least 256-bytes long, to be able to contain the error message.
    **/
    bool is_CImg3d(const bool full_check=true, char *const error_message=0) const {
      if (error_message) *error_message = 0;

      // Check instance dimension and header.
      if (_width!=1 || _height<8 || _depth!=1 || _spectrum!=1) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d has invalid dimensions (%u,%u,%u,%u)",
                                         _width,_height,_depth,_spectrum);
        return false;
      }
      const T *ptrs = _data, *const ptre = end();
      if (!_is_CImg3d(*(ptrs++),'C') || !_is_CImg3d(*(ptrs++),'I') || !_is_CImg3d(*(ptrs++),'m') ||
          !_is_CImg3d(*(ptrs++),'g') || !_is_CImg3d(*(ptrs++),'3') || !_is_CImg3d(*(ptrs++),'d')) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d header not found");
        return false;
      }
      if (!cimg::type<T>::is_finite(*ptrs) || !cimg::type<T>::is_finite(ptrs[1])) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "Specified numbers of vertices/primitives (%g/%g) are invalid",
                                         (double)*ptrs,(double)ptrs[1]);
        return false;
      }

      const unsigned int
        nb_points = cimg::float2uint(*(ptrs++)),
        nb_primitives = cimg::float2uint(*(ptrs++));

      // Check the consistency of number of vertices / primitives.
      if (!full_check) {
        const ulongT minimal_size = 8UL + 3*nb_points + 6*nb_primitives;
        if (_data + minimal_size>ptre) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) has only %lu values, "
                                           "while at least %lu values were expected",
                                           nb_points,nb_primitives,(unsigned long)size(),(unsigned long)minimal_size);
          return false;
        }
      }

      // Check the consistency of vertex data.
      if (!nb_points) {
        if (nb_primitives) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) defines no vertices but %u primitives",
                                           nb_points,nb_primitives,nb_primitives);
          return false;
        }
        if (ptrs!=ptre) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) is an empty object but contains %u value%s "
                                           "more than expected",
                                           nb_points,nb_primitives,(unsigned int)(ptre - ptrs),(ptre - ptrs)>1?"s":"");
          return false;
        }
        return true;
      }
      if (ptrs + 3*nb_points>ptre) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d (%u,%u) defines only %u vertices data",
                                         nb_points,nb_primitives,(unsigned int)(ptre - ptrs)/3);
        return false;
      }
      ptrs+=3*nb_points;

      // Check the consistency of primitive data.
      if (ptrs==ptre) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d (%u,%u) defines %u vertices but no primitive",
                                         nb_points,nb_primitives,nb_points);
        return false;
      }

      if (!full_check) return true;

      for (unsigned int p = 0; p<nb_primitives; ++p) {
        const unsigned int nb_inds = (unsigned int)*(ptrs++);
        switch (nb_inds) {
        case 1 : { // Point
          const unsigned int i0 = cimg::float2uint(*(ptrs++));
          if (i0>=nb_points) {
            if (error_message) cimg_snprintf(error_message,256,
                                             "CImg3d (%u,%u) refers to invalid vertex index %u in point primitive [%u]",
                                             nb_points,nb_primitives,i0,p);
            return false;
          }
        } break;
        case 5 : { // Sphere
          const unsigned int
            i0 = cimg::float2uint(*(ptrs++)),
            i1 = cimg::float2uint(*(ptrs++));
          ptrs+=3;
          if (i0>=nb_points || i1>=nb_points) {
            if (error_message) cimg_snprintf(error_message,256,
                                             "CImg3d (%u,%u) refers to invalid vertex indices (%u,%u) in "
                                             "sphere primitive [%u]",
                                             nb_points,nb_primitives,i0,i1,p);
            return false;
          }
        } break;
        case 2 : case 6 : { // Segment
          const unsigned int
            i0 = cimg::float2uint(*(ptrs++)),
            i1 = cimg::float2uint(*(ptrs++));
          if (nb_inds==6) ptrs+=4;
          if (i0>=nb_points || i1>=nb_points) {
            if (error_message) cimg_snprintf(error_message,256,
                                             "CImg3d (%u,%u) refers to invalid vertex indices (%u,%u) in "
                                             "segment primitive [%u]",
                                             nb_points,nb_primitives,i0,i1,p);
            return false;
          }
        } break;
        case 3 : case 9 : { // Triangle
          const unsigned int
            i0 = cimg::float2uint(*(ptrs++)),
            i1 = cimg::float2uint(*(ptrs++)),
            i2 = cimg::float2uint(*(ptrs++));
          if (nb_inds==9) ptrs+=6;
          if (i0>=nb_points || i1>=nb_points || i2>=nb_points) {
            if (error_message) cimg_snprintf(error_message,256,
                                             "CImg3d (%u,%u) refers to invalid vertex indices (%u,%u,%u) in "
                                             "triangle primitive [%u]",
                                             nb_points,nb_primitives,i0,i1,i2,p);
            return false;
          }
        } break;
        case 4 : case 12 : { // Quadrangle
          const unsigned int
            i0 = cimg::float2uint(*(ptrs++)),
            i1 = cimg::float2uint(*(ptrs++)),
            i2 = cimg::float2uint(*(ptrs++)),
            i3 = cimg::float2uint(*(ptrs++));
          if (nb_inds==12) ptrs+=8;
          if (i0>=nb_points || i1>=nb_points || i2>=nb_points || i3>=nb_points) {
            if (error_message) cimg_snprintf(error_message,256,
                                             "CImg3d (%u,%u) refers to invalid vertex indices (%u,%u,%u,%u) in "
                                             "quadrangle primitive [%u]",
                                             nb_points,nb_primitives,i0,i1,i2,i3,p);
            return false;
          }
        } break;
        default :
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) defines an invalid primitive [%u] of size %u",
                                           nb_points,nb_primitives,p,nb_inds);
          return false;
        }
        if (ptrs>ptre) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) has incomplete primitive data for primitive [%u], "
                                           "%u values missing",
                                           nb_points,nb_primitives,p,(unsigned int)(ptrs - ptre));
          return false;
        }
      }

      // Check the consistency of color data.
      if (ptrs==ptre) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d (%u,%u) defines no color/texture data",
                                         nb_points,nb_primitives);
        return false;
      }
      for (unsigned int c = 0; c<nb_primitives; ++c) {
        if (*(ptrs++)!=(T)-128) ptrs+=2;
        else if ((ptrs+=3)<ptre) {
          const unsigned int
            w = (unsigned int)cimg::float2uint(*(ptrs - 3)),
            h = (unsigned int)*(ptrs - 2),
            s = (unsigned int)*(ptrs - 1);
          if (!h && !s) {
            if (w>=c) {
              if (error_message) cimg_snprintf(error_message,256,
                                               "CImg3d (%u,%u) refers to invalid shared sprite/texture index %u "
                                               "for primitive [%u]",
                                               nb_points,nb_primitives,w,c);
              return false;
            }
          } else ptrs+=w*h*s;
        }
        if (ptrs>ptre) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) has incomplete color/texture data for primitive [%u], "
                                           "%u values missing",
                                           nb_points,nb_primitives,c,(unsigned int)(ptrs - ptre));
          return false;
        }
      }

      // Check the consistency of opacity data.
      if (ptrs==ptre) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d (%u,%u) defines no opacity data",
                                         nb_points,nb_primitives);
        return false;
      }
      for (unsigned int o = 0; o<nb_primitives; ++o) {
        if (*(ptrs++)==(T)-128 && (ptrs+=3)<ptre) {
          const unsigned int
            w = (unsigned int)cimg::float2uint(*(ptrs - 3)),
            h = (unsigned int)*(ptrs - 2),
            s = (unsigned int)*(ptrs - 1);
          if (!h && !s) {
            if (w>=o) {
              if (error_message) cimg_snprintf(error_message,256,
                                               "CImg3d (%u,%u) refers to invalid shared opacity index %u "
                                               "for primitive [%u]",
                                               nb_points,nb_primitives,w,o);
              return false;
            }
          } else ptrs+=w*h*s;
        }
        if (ptrs>ptre) {
          if (error_message) cimg_snprintf(error_message,256,
                                           "CImg3d (%u,%u) has incomplete opacity data for primitive [%u]",
                                           nb_points,nb_primitives,o);
          return false;
        }
      }

      // Check end of data.
      if (ptrs<ptre) {
        if (error_message) cimg_snprintf(error_message,256,
                                         "CImg3d (%u,%u) contains %u value%s more than expected",
                                         nb_points,nb_primitives,(unsigned int)(ptre - ptrs),(ptre - ptrs)>1?"s":"");
        return false;
      }
      return true;
    }

    static bool _is_CImg3d(const T val, const char c) {
      return val>=(T)c && val<(T)(c + 1);
    }

    //@}
    //-------------------------------------
    //
    //! \name Mathematical Functions
    //@{
    //-------------------------------------

    // Define the math formula parser/compiler and expression evaluator.
    struct _cimg_math_parser {
      CImgList<ulongT> _code, _code_begin_t, _code_end_t, code_begin, code_end, &code, &code_begin_t, &code_end_t;
      CImgList<doubleT> _list_median, _list_norm, _list_stats, &list_median, &list_norm, &list_stats;
      CImgList<charT> macro_def, macro_body, variable_def;
      CImgList<T>& imglist;

      CImg<uintT> constcache_inds, level, mem_img_stats, reserved_label, variable_pos;
      CImg<doubleT> _img_stats, &img_stats, constcache_vals, mem;
      CImg<intT> memmerge, memtype;
      CImg<charT> expr, pexpr;
      CImg<ulongT> opcode;
      CImg<T> &imgout;

      const CImg<ulongT> *const p_break, *p_code, *p_code_end;
      const CImg<T>& imgin;

      unsigned int break_type, constcache_size, debug_indent, mem_img_index, mem_img_median, mem_img_norm, mempos,
        _0_index, _1_index, result_dim, result_end_dim;
      bool is_end_code, is_fill, is_noncritical_run, is_parallelizable, need_input_copy, return_comp;
      const char *const calling_function, *s_op, *ss_op;
      double *result, *result_end;
      char *user_macro;
      cimg_uint64 rng;

      typedef double (*mp_func)(_cimg_math_parser&);

#define _cimg_mp_calling_function s_calling_function()._data
#define _cimg_mp_check_const_scalar(arg,n_arg,mode) check_const_scalar(arg,n_arg,mode,ss,se,saved_char)
#define _cimg_mp_check_const_index(arg) check_const_index(arg,ss,se,saved_char)
#define _cimg_mp_check_notnan_index(arg,s_arg) check_notnan_index(arg,s_arg,ss,se,saved_char)
#define _cimg_mp_check_list() check_list(ss,se,saved_char)
#define _cimg_mp_check_matrix_square(arg,n_arg) check_matrix_square(arg,n_arg,ss,se,saved_char)
#define _cimg_mp_check_type(arg,n_arg,mode,N) check_type(arg,n_arg,mode,N,ss,se,saved_char)
#define _cimg_mp_const_scalar(val) _cimg_mp_return(const_scalar((double)(val)))
#define _cimg_mp_op(s) s_op = s; ss_op = ss
#define _cimg_mp_return(x) { *se = saved_char; s_op = previous_s_op; ss_op = previous_ss_op; return x; }
#define _cimg_mp_return_nan() _cimg_mp_return(_cimg_mp_slot_nan)
#define _cimg_mp_same(x) _cimg_mp_return(same(x));
#define _cimg_mp_scalar0(op) _cimg_mp_return(scalar0(mp_##op))
#define _cimg_mp_scalar1(op,i1) _cimg_mp_return(scalar1(mp_##op,i1))
#define _cimg_mp_scalar2(op,i1,i2) _cimg_mp_return(scalar2(mp_##op,i1,i2))
#define _cimg_mp_scalar3(op,i1,i2,i3) _cimg_mp_return(scalar3(mp_##op,i1,i2,i3))
#define _cimg_mp_scalar4(op,i1,i2,i3,i4) _cimg_mp_return(scalar4(mp_##op,i1,i2,i3,i4))
#define _cimg_mp_scalar5(op,i1,i2,i3,i4,i5) _cimg_mp_return(scalar5(mp_##op,i1,i2,i3,i4,i5))
#define _cimg_mp_scalar6(op,i1,i2,i3,i4,i5,i6) _cimg_mp_return(scalar6(mp_##op,i1,i2,i3,i4,i5,i6))
#define _cimg_mp_scalar8(op,i1,i2,i3,i4,i5,i6,i7,i8) _cimg_mp_return(scalar8(mp_##op,i1,i2,i3,i4,i5,i6,i7,i8))
#define _cimg_mp_strerr \
  *se = saved_char; \
  for (s0 = ss; s0>expr._data && *s0!=';'; --s0) {} \
  if (*s0==';') ++s0; \
  while (cimg::is_blank(*s0)) ++s0; \
  cimg::strellipsize(s0,64)
#define _cimg_mp_vector1(op,i1) _cimg_mp_return(vector1(mp_vector_##op,size(i1),i1))
#define _cimg_mp_vector2(op,i1,i2) { \
    const unsigned int _mp_si1 = size(i1), _mp_si2 = size(i2); \
    _cimg_mp_return(vector2(!_mp_si1 && _mp_si2?mp_vector_##op##_sv:\
                            _mp_si1 && !_mp_si2?mp_vector_##op##_vs:mp_vector_##op##_vv,\
                            std::max(_mp_si1,_mp_si2),i1,i2)); }
#define _cimg_mp_vector3(op,i1,i2,i3) _cimg_mp_return(vector3(mp_vector_##op,size(i1),i1,i2,i3))
#define _cimg_mp_self_vector1(op,i1) CImg<ulongT>::vector((ulongT)(op),i1,size(i1)).move_to(code)
#define _cimg_mp_self_vector2(op,i1,i2) CImg<ulongT>::vector((ulongT)(op),i1,size(i1),i2).move_to(code)

      // Constructors / Destructors.
      ~_cimg_math_parser() {
        cimg::srand(rng);
      }

      _cimg_math_parser(const char *const expression, const char *const funcname=0,
                        const CImg<T>& img_input=CImg<T>::const_empty(), CImg<T> *const img_output=0,
                        CImgList<T> *const list_images=0, const bool _is_fill=false):
        code(_code),code_begin_t(_code_begin_t),code_end_t(_code_end_t),
        list_median(_list_median),list_norm(_list_norm),list_stats(_list_stats),
        imglist(list_images?*list_images:CImgList<T>::empty()),
        img_stats(_img_stats),
        imgout(img_output?*img_output:CImg<T>::empty()),
        p_break((CImg<ulongT>*)(cimg_ulong)-2),
        imgin(img_input),
        break_type(0),constcache_size(0),debug_indent(0),mem_img_index(~0U),mem_img_median(~0U),mem_img_norm(~0U),
          _0_index(~0U),_1_index(~0U),result_dim(0),result_end_dim(0),
        is_fill(_is_fill),is_noncritical_run(false),is_parallelizable(true),need_input_copy(false),
        calling_function(funcname?funcname:"cimg_math_parser"),
        result_end(0),
        user_macro(0),
        rng((cimg::_rand(),cimg::rng())) {

#if cimg_use_openmp!=0
        rng+=omp_get_thread_num();
#endif
        if (!expression || !*expression)
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: Empty expression.",
                                      pixel_type(),_cimg_mp_calling_function);
        const char *_expression = expression;
        while (*_expression && (cimg::is_blank(*_expression) || *_expression==';')) ++_expression;
        CImg<charT>::string(_expression).move_to(expr);
        char *ps;
        if (expr._width>1) {
          ps = &expr.back() - 1;
          while (ps>expr._data && (cimg::is_blank(*ps) || *ps==';')) --ps;
          *(++ps) = 0; expr._width = (unsigned int)(ps - expr._data + 1);
        }

        // Ease the retrieval of previous non-space characters afterwards.
        pexpr.assign(expr._width);
        char c, *pe = pexpr._data;
        for (ps = expr._data, c = ' '; *ps; ++ps) {
          if (!cimg::is_blank(*ps)) c = *ps; else *ps = ' ';
          *(pe++) = c;
        }
        *pe = 0;
        level = get_level(expr);

        // Init constant values.
#define _cimg_mp_interpolation (reserved_label[31]!=~0U?reserved_label[31]:0)
#define _cimg_mp_boundary (reserved_label[32]!=~0U?reserved_label[32]:0)
#define _cimg_mp_slot_t 17
#define _cimg_mp_slot_nan 30
#define _cimg_mp_slot_x 31
#define _cimg_mp_slot_y 32
#define _cimg_mp_slot_z 33
#define _cimg_mp_slot_c 34

        mem.assign(96);
        for (unsigned int i = 0; i<=10; ++i) mem[i] = (double)i; // mem[0-10] = 0...10
        for (unsigned int i = 1; i<=5; ++i) mem[i + 10] = -(double)i; // mem[11-15] = -1...-5
        mem[16] = 0.5;
        mem[_cimg_mp_slot_t] = 0; // thread_id
        mem[18] = (double)imgin._width; // w
        mem[19] = (double)imgin._height; // h
        mem[20] = (double)imgin._depth; // d
        mem[21] = (double)imgin._spectrum; // s
        mem[22] = (double)imgin._is_shared; // r
        mem[23] = (double)imgin._width*imgin._height; // wh
        mem[24] = (double)imgin._width*imgin._height*imgin._depth; // whd
        mem[25] = (double)imgin._width*imgin._height*imgin._depth*imgin._spectrum; // whds
        mem[26] = (double)imglist._width; // l
        mem[27] = std::exp(1.); // e
        mem[28] = cimg::PI; // pi
        mem[29] = DBL_EPSILON; // eps
        mem[_cimg_mp_slot_nan] = cimg::type<double>::nan(); // nan

        // Type property for each value in memory :
        // { -1 = reserved (e.g. variable) | 0 = computation scalar |
        //    1 = compile-time constant | N>1 = start of a vector(#N-1) }.
        memtype.assign(mem._width,1,1,1,0);
        for (unsigned int i = 0; i<_cimg_mp_slot_x; ++i) memtype[i] = 1;
        memtype[_cimg_mp_slot_t] = memtype[_cimg_mp_slot_x] = memtype[_cimg_mp_slot_y] =
          memtype[_cimg_mp_slot_z] = memtype[_cimg_mp_slot_c] = -1;
        mempos = _cimg_mp_slot_c + 1;
        variable_pos.assign(8);

        reserved_label.assign(128,1,1,1,~0U);
        // reserved_label[0-35] are used to store the memory index of these variables:
        // [0] = wh, [1] = whd, [2] = whds, [3] = pi, [4] = im, [5] = iM, [6] = ia, [7] = iv, [8] = id,
        // [9] = is, [10] = ip, [11] = ic, [12] = in, [13] = xm, [14] = ym, [15] = zm, [16] = cm, [17] = xM,
        // [18] = yM, [19] = zM, [20] = cM, [21] = i0...[30] = i9, [31] = interpolation, [32] = boundary, [33] = eps,
        // [34] = _0, [35] = _1

        // Compile expression into a sequence of opcodes.
        s_op = ""; ss_op = expr._data;
        const unsigned int ind_result = compile(expr._data,expr._data + expr._width - 1,0,0,0);
        if (!is_const_scalar(ind_result) && ind_result!=_cimg_mp_slot_t &&
            ind_result!=_0_index && ind_result!=_1_index) {
          if (is_vector(ind_result))
            CImg<doubleT>(&mem[ind_result] + 1,size(ind_result),1,1,1,true).
              fill(cimg::type<double>::nan());
          else mem[ind_result] = cimg::type<double>::nan();
        }
        if (mem._width>=256 && mem._width - mempos>=mem._width/2) mem.resize(mempos,1,1,1,-1);
        result_dim = size(ind_result);
        result = mem._data + ind_result;

        // Free resources used for compiling expression and prepare evaluation.
        memtype.assign();
        constcache_vals.assign();
        constcache_inds.assign();
        level.assign();
        variable_pos.assign();
        reserved_label.assign();
        expr.assign();
        pexpr.assign();
        opcode.assign();
        opcode._is_shared = true;
        p_code_end = code.end();
        begin();
      }

      _cimg_math_parser():
        code(_code),code_begin_t(_code_begin_t),code_end_t(_code_end_t),
        list_median(_list_median),list_norm(_list_norm),list_stats(_list_stats),
        imglist(CImgList<T>::empty()),
        img_stats(_img_stats),
        imgout(CImg<T>::empty()),
        p_break((CImg<ulongT>*)(cimg_ulong)-2),p_code_end(0),
        imgin(CImg<T>::const_empty()),
        break_type(0),constcache_size(0),debug_indent(0),result_dim(0),result_end_dim(0),
        is_fill(false),is_noncritical_run(false),is_parallelizable(true),need_input_copy(false),
        calling_function(0),
        result_end(0),
        rng(0) {
        mem.assign(1 + _cimg_mp_slot_c,1,1,1,0); // Makes it possible to skip 'is_empty?' test in operator()()
        result = mem._data;
      }

      _cimg_math_parser(const _cimg_math_parser& mp):
        code(mp.code),code_begin_t(mp.code_begin_t),code_end_t(mp.code_end_t),
        list_median(mp.list_median),list_norm(mp.list_norm),list_stats(mp.list_stats),
        imglist(mp.imglist),
        img_stats(mp.img_stats),mem(mp.mem),
        imgout(mp.imgout),
        p_break(mp.p_break),p_code_end(mp.p_code_end),
        imgin(mp.imgin),
        break_type(0),constcache_size(0),debug_indent(0),result_dim(mp.result_dim),result_end_dim(mp.result_end_dim),
        is_fill(mp.is_fill),is_noncritical_run(mp.is_noncritical_run),is_parallelizable(mp.is_parallelizable),
          need_input_copy(mp.need_input_copy),
        calling_function(0),
        result(mem._data + (mp.result - mp.mem._data)),
          result_end(mp.result_end?mem._data + (mp.result_end - mp.mem._data):0),
        rng((cimg::_rand(),cimg::rng())) {

#if cimg_use_openmp!=0
        mem[_cimg_mp_slot_t] = (double)omp_get_thread_num();
        rng+=omp_get_thread_num();
#endif
        opcode.assign();
        opcode._is_shared = true;
      }

      // Compilation procedure.
      unsigned int compile(char *ss, char *se, const unsigned int depth, unsigned int *const p_ref,
                           unsigned char block_flags) {
        if (depth>256) {
          cimg::strellipsize(expr,64);
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: Call stack overflow (infinite recursion?), "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,
                                      (ss - 4)>expr._data?ss - 4:expr._data);
        }
        char c1, c2;

        // Simplify expression when possible.
        do {
          c2 = 0;
          if (ss<se) {
            while (*ss && (cimg::is_blank(*ss) || *ss==';')) ++ss; // Remove leading blanks and ';'
            while (se>ss && (cimg::is_blank(c1 = *(se - 1)) || c1==';')) --se; // Remove trailing blanks and ';'
          }
          while (*ss=='(' && *(se - 1)==')' && std::strchr(ss,')')==se - 1) { // Remove useless start/end parentheses
            ++ss; --se; c2 = 1;
          }
          if (*ss=='_' && ss + 1<se && ss[1]=='(') { // Remove leading '_(something)' comment
            const unsigned int clevel = level[ss - expr._data];
            ss+=2;
            while (ss<se && (*ss!=')' || level[ss - expr._data]!=clevel)) ++ss;
            if (ss<se) ++ss;
            if (ss>=se) return _cimg_mp_slot_nan;
            c2 = 1;
          }
        } while (c2 && ss<se);

        if (se<=ss || !*ss) {
          cimg::strellipsize(expr,64);
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s Missing %s, in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",
                                      *s_op=='F'?"argument":"item",
                                      ss_op);
        }

        static const size_t siz_ref = 7*sizeof(unsigned int);
        const char *const previous_s_op = s_op, *const previous_ss_op = ss_op;
        const unsigned int depth1 = depth + 1;
        unsigned int pos, p1, p2, p3, arg1, arg2, arg3, arg4, arg5, arg6;
        char
          *const se1 = se - 1, *const se2 = se - 2, *const se3 = se - 3, *const se4 = se - 4,
          *const ss1 = ss + 1, *const ss2 = ss + 2, *const ss3 = ss + 3, *const ss4 = ss + 4,
          *const ss5 = ss + 5, *const ss6 = ss + 6, *const ss7 = ss + 7, *const ss8 = ss + 8,
          *s, *ps, *ns, *s0, *s1, *s2, *s3, sep = 0, end = 0;
        double val = 0, val1, val2, val3;
        mp_func op;

        return_comp = false;

        // Bits of 'block_flags' tell about in which code block we currently are:
        // 0: critical(), 1: begin(), 2: begin_t(), 3: end(), 4: end_t(), 5: is_new_variable_assignment
        const bool
          is_inside_critical = (bool)(block_flags&1),
          is_inside_begin = (bool)(block_flags&2),
          is_inside_begin_t = (bool)(block_flags&4),
          is_inside_end = (bool)(block_flags&8),
          is_inside_end_t = (bool)(block_flags&16),
          is_new_variable_assignment = (bool)(block_flags&32);
        block_flags&=31; // Deeper calls to 'compile()' won't automatically pass 'is_new_variable_assigment=true'

        // 'p_ref' is a 'unsigned int[7]' used to return a reference to an image or vector value
        // linked to the returned memory slot (reference that cannot be determined at compile time).
        // p_ref[0] can be { 0 = scalar (unlinked) | 1 = vector value | 2 = image value (offset) |
        //                   3 = image value (coordinates) | 4 = image value as a vector (offset) |
        //                   5 = image value as a vector (coordinates) }.
        // Depending on p_ref[0], the remaining p_ref[k] have the following meaning:
        // When p_ref[0]==0, p_ref is actually unlinked.
        // When p_ref[0]==1, p_ref = [ 1, vector_ind, offset ].
        // When p_ref[0]==2, p_ref = [ 2, image_ind (or ~0U), is_relative, offset ].
        // When p_ref[0]==3, p_ref = [ 3, image_ind (or ~0U), is_relative, x, y, z, c ].
        // When p_ref[0]==4, p_ref = [ 4, image_ind (or ~0U), is_relative, offset ].
        // When p_ref[0]==5, p_ref = [ 5, image_ind (or ~0U), is_relative, x, y, z ].
        if (p_ref) { *p_ref = 0; p_ref[1] = p_ref[2] = p_ref[3] = p_ref[4] = p_ref[5] = p_ref[6] = ~0U; }

        const char saved_char = *se; *se = 0;
        const unsigned int clevel = level[ss - expr._data], clevel1 = clevel + 1;
        bool is_sth, is_relative;
        CImg<uintT> ref;
        CImg<charT> variable_name;
        CImgList<ulongT> l_opcode;

        // Look for a single value or a predefined variable.
        int nb = 0;
        is_sth = *ss=='-';
        s = ss + (*ss=='+' || is_sth?1:0);
        if (*s=='i' || *s=='I' || *s=='n' || *s=='N') { // Particular cases : +/-NaN and +/-Inf
          if (!cimg::strcasecmp(s,"inf")) { val = cimg::type<double>::inf(); nb = 1; }
          else if (!cimg::strcasecmp(s,"nan")) { val = cimg::type<double>::nan(); nb = 1; }
        } else if (*s=='0' && (s[1]=='x' || s[1]=='X') && s[2]!='-') { // Hexadecimal literal
          cimg_uint64 num;
          if ((nb = cimg_sscanf(s + 2,cimg_fhex64 "%c",&num,&sep))==1 || (nb==2 && sep=='%'))
            val = (double)num;
        } else if (*s=='0' && (s[1]=='b' || s[1]=='B') && s[2]!='-') { // Binary literal
          variable_name.assign(65);
          if ((nb = cimg_sscanf(s + 2,"%64[01]%c",variable_name.data(),&sep))==1 || (nb==2 && sep=='%'))
            val = (double)cimg::strtoll(variable_name,0,2);
          variable_name.assign();
        }
        if (is_sth && nb) val = -val;
        else if (!nb) nb = cimg_sscanf(ss,"%lf%c%c",&val,&(sep=0),&(end=0));
        if (nb==1) _cimg_mp_const_scalar(val);
        if (nb==2 && sep=='%') _cimg_mp_const_scalar(val/100);

        if (ss1==se) switch (*ss) { // One-char reserved variable
          case 'c' : _cimg_mp_return(reserved_label[(int)'c']!=~0U?reserved_label[(int)'c']:_cimg_mp_slot_c);
          case 'd' : _cimg_mp_return(reserved_label[(int)'d']!=~0U?reserved_label[(int)'d']:20);
          case 'e' : _cimg_mp_return(reserved_label[(int)'e']!=~0U?reserved_label[(int)'e']:27);
          case 'h' : _cimg_mp_return(reserved_label[(int)'h']!=~0U?reserved_label[(int)'h']:19);
          case 'k' :
            if (reserved_label[(int)'k']!=~0U) _cimg_mp_return(reserved_label[(int)'k']);
            pos = get_mem_img_index();
            if (pos!=~0U) _cimg_mp_return(pos);
            _cimg_mp_return_nan();
          case 'l' : _cimg_mp_return(reserved_label[(int)'l']!=~0U?reserved_label[(int)'l']:26);
          case 'r' : _cimg_mp_return(reserved_label[(int)'r']!=~0U?reserved_label[(int)'r']:22);
          case 's' : _cimg_mp_return(reserved_label[(int)'s']!=~0U?reserved_label[(int)'s']:21);
          case 't' : _cimg_mp_return(reserved_label[(int)'t']!=~0U?reserved_label[(int)'t']:_cimg_mp_slot_t);
          case 'n' :
            if (reserved_label[(int)'n']!=~0U) _cimg_mp_return(reserved_label[(int)'n']);
#if cimg_use_openmp!=0
            _cimg_mp_const_scalar((double)omp_get_max_threads());
#else
            _cimg_mp_return(1);
#endif
          case 'w' : _cimg_mp_return(reserved_label[(int)'w']!=~0U?reserved_label[(int)'w']:18);
          case 'x' : _cimg_mp_return(reserved_label[(int)'x']!=~0U?reserved_label[(int)'x']:_cimg_mp_slot_x);
          case 'y' : _cimg_mp_return(reserved_label[(int)'y']!=~0U?reserved_label[(int)'y']:_cimg_mp_slot_y);
          case 'z' : _cimg_mp_return(reserved_label[(int)'z']!=~0U?reserved_label[(int)'z']:_cimg_mp_slot_z);
          case 'u' :
            if (reserved_label[(int)'u']!=~0U) _cimg_mp_return(reserved_label[(int)'u']);
            _cimg_mp_scalar0(rand_double_0_1);
          case 'v' :
            if (reserved_label[(int)'v']!=~0U) _cimg_mp_return(reserved_label[(int)'v']);
            _cimg_mp_scalar0(rand_int_0_1);
          case 'g' :
            if (reserved_label[(int)'g']!=~0U) _cimg_mp_return(reserved_label[(int)'g']);
            _cimg_mp_scalar0(rand_double_gaussian);
          case 'i' :
            if (reserved_label[(int)'i']!=~0U) _cimg_mp_return(reserved_label[(int)'i']);
            _cimg_mp_scalar0(i);
          case 'I' :
            _cimg_mp_op("Variable 'I'");
            if (reserved_label[(int)'I']!=~0U) _cimg_mp_return(reserved_label[(int)'I']);
            if (!imgin._spectrum) _cimg_mp_return(0);
            need_input_copy = true;
            pos = vector(imgin._spectrum);
            CImg<ulongT>::vector((ulongT)mp_I,pos,imgin._spectrum).move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          case 'R' :
            if (reserved_label[(int)'R']!=~0U) _cimg_mp_return(reserved_label[(int)'R']);
            need_input_copy = true;
            _cimg_mp_scalar8(ijxyzc1,0,~0U,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,0,0,0);
          case 'G' :
            if (reserved_label[(int)'G']!=~0U) _cimg_mp_return(reserved_label[(int)'G']);
            need_input_copy = true;
            _cimg_mp_scalar8(ijxyzc1,0,~0U,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,1,0,0);
          case 'B' :
            if (reserved_label[(int)'B']!=~0U) _cimg_mp_return(reserved_label[(int)'B']);
            need_input_copy = true;
            _cimg_mp_scalar8(ijxyzc1,0,~0U,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,2,0,0);
          case 'A' :
            if (reserved_label[(int)'A']!=~0U) _cimg_mp_return(reserved_label[(int)'A']);
            need_input_copy = true;
            _cimg_mp_scalar8(ijxyzc1,0,~0U,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,3,0,0);
          }
        else if (ss2==se) { // Two-chars reserved variable
          arg1 = arg2 = ~0U;
          if (*ss=='w' && *ss1=='h') // wh
            _cimg_mp_return(reserved_label[0]!=~0U?reserved_label[0]:23);
          if (*ss=='p' && *ss1=='i') // pi
            _cimg_mp_return(reserved_label[3]!=~0U?reserved_label[3]:28);
          if (*ss=='_' && *ss1=='0') { // _0
            if (reserved_label[34]!=~0U) _cimg_mp_return(reserved_label[34]);
            if (_0_index==~0U) {
              if (imgin.is_empty()) _cimg_mp_return_nan();
              _0_index = vector(imgin._spectrum);
              std::memset(&mem[_0_index] + 1,0,imgin._spectrum*sizeof(double));
              set_reserved_vector(_0_index);
            }
            _cimg_mp_return(_0_index);
          }
          if (*ss=='_' && *ss1=='1') { // _1
            if (reserved_label[35]!=~0U) _cimg_mp_return(reserved_label[35]);
            if (_1_index==~0U) {
              if (imgin.is_empty()) _cimg_mp_return_nan();
              _1_index = vector(imgin._spectrum);
              cimg_forC(imgin,c) mem[_1_index + 1 + c] = 1.0;
              set_reserved_vector(_1_index);
            }
            _cimg_mp_return(_1_index);
          }
          if (*ss=='i') {
            if (*ss1>='0' && *ss1<='9') { // i0...i9
              pos = 21 + *ss1 - '0';
              if (reserved_label[pos]!=~0U) _cimg_mp_return(reserved_label[pos]);
              need_input_copy = true;
              _cimg_mp_scalar8(ijxyzc1,0,~0U,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,pos - 21,0,0);
            }
            switch (*ss1) {
            case 'a' : arg1 = 6; arg2 = 2; break; // ia
            case 'c' : // ic
              if (reserved_label[11]!=~0U) _cimg_mp_return(reserved_label[11]);
              if (mem_img_median==~0U) mem_img_median = imgin?const_scalar(imgin.median()):0;
              _cimg_mp_return(mem_img_median);
              break;
            case 'd' : arg1 = 8; arg2 = 3; break; // id
            case 'm' : arg1 = 4; arg2 = 0; break; // im
            case 'M' : arg1 = 5; arg2 = 1; break; // iM
            case 'n' : // in
              if (reserved_label[12]!=~0U) _cimg_mp_return(reserved_label[12]);
              if (mem_img_norm==~0U) mem_img_norm = imgin?const_scalar(imgin.magnitude(2)):0;
              _cimg_mp_return(mem_img_norm);
              break;
            case 'p' : arg1 = 10; arg2 = 13; break; // ip
            case 's' : arg1 = 9; arg2 = 12; break; // is
            case 'v' : arg1 = 7; arg2 = 3; break; // iv
            }
          }
          else if (*ss1=='m') switch (*ss) {
            case 'x' : arg1 = 13; arg2 = 4; break; // xm
            case 'y' : arg1 = 14; arg2 = 5; break; // ym
            case 'z' : arg1 = 15; arg2 = 6; break; // zm
            case 'c' : arg1 = 16; arg2 = 7; break; // cm
            }
          else if (*ss1=='M') switch (*ss) {
            case 'x' : arg1 = 17; arg2 = 8; break; // xM
            case 'y' : arg1 = 18; arg2 = 9; break; // yM
            case 'z' : arg1 = 19; arg2 = 10; break; // zM
            case 'c' : arg1 = 20; arg2 = 11; break; // cM
            }
          if (arg1!=~0U) {
            if (reserved_label[arg1]!=~0U) _cimg_mp_return(reserved_label[arg1]);
            if (!img_stats) {
              img_stats.assign(1,15,1,1,0).fill(imgin.get_stats(),false);
              mem_img_stats.assign(1,15,1,1,~0U);
            }
            if (mem_img_stats[arg2]==~0U) mem_img_stats[arg2] = const_scalar(img_stats[arg2]);
            if (arg1==8) _cimg_mp_const_scalar(std::sqrt(img_stats[arg2])); // id: std variation
            _cimg_mp_return(mem_img_stats[arg2]);
          }
        } else if (ss3==se) { // Three-chars reserved variable
          if (*ss=='w' && *ss1=='h' && *ss2=='d') // whd
            _cimg_mp_return(reserved_label[1]!=~0U?reserved_label[1]:24);
          if (*ss=='e' && *ss1=='p' && *ss2=='s') // eps
            _cimg_mp_return(reserved_label[33]!=~0U?reserved_label[33]:29);
        } else if (ss4==se) { // Four-chars reserved variable
          if (*ss=='w' && *ss1=='h' && *ss2=='d' && *ss3=='s') // whds
            _cimg_mp_return(reserved_label[2]!=~0U?reserved_label[2]:25);
        }

        pos = ~0U;
        is_sth = false;
        for (s0 = ss, s1 = ss1; s1<se1; ++s1) {
          if (!(s1 = (char*)std::memchr(s1,';',se1 - s1))) break;
          if (level[s1 - expr._data]==clevel) { // Separator ';'
            is_end_code = false;
            arg1 = compile(s0,s1++,depth,0,block_flags);
            if (!is_end_code) pos = arg1; // 'end()' and 'end_t()' return void
            is_sth = true;
            while (*s1 && (cimg::is_blank(*s1) || *s1==';')) ++s1;
            s0 = s1;
          }
        }
        if (is_sth) {
          is_end_code = false;
          arg1 = compile(s0,se,depth,p_ref,block_flags);
          if (!is_end_code) pos = arg1; // 'end()' and 'end_t()' return void
          _cimg_mp_return(pos!=~0U?pos:_cimg_mp_slot_nan);
        }

        // Declare / assign variable, vector value or image value.
        for (s = ss1; s<se1; ++s) {
          if (!(s = (char*)std::memchr(s,'=',se1 - s))) break;
          ps = s - 1; ns = s + 1;
          const char pc = *ps;
          if (level[s - expr._data]==clevel &&
              *ns!='=' && pc!='=' && pc!='>' && pc!='<' && pc!='!' &&
              pc!='+' && pc!='-' && pc!='*' && pc!='/' && pc!='%' &&
              pc!='>' && pc!='<' && pc!='&' && pc!='|' && pc!='^') {
            variable_name.assign(ss,(unsigned int)(s + 1 - ss)).back() = 0;
            cimg::strpare(variable_name,false,true);
            const unsigned int l_variable_name = (unsigned int)std::strlen(variable_name);
            char *const ve1 = ss + l_variable_name - 1;
            _cimg_mp_op("Operator '='");

            // Assign image value (direct).
            if (l_variable_name>2 && (*ss=='i' || *ss=='j' || *ss=='I' || *ss=='J') && (*ss1=='(' || *ss1=='[') &&
                (reserved_label[(int)*ss]==~0U || *ss1=='(' || !is_vector(reserved_label[(int)*ss]))) {
              is_relative = *ss=='j' || *ss=='J';

              if (*ss1=='[' && *ve1==']') { // i/j/I/J[_#ind,offset] = value
                if (!is_inside_critical) is_parallelizable = false;
                if (*ss2=='#') { // Index specified
                  s0 = ss3; while (s0<ve1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                  p1 = compile(ss3,s0++,depth1,0,block_flags);
                  _cimg_mp_check_notnan_index(p1,ss3);
                  _cimg_mp_check_list();
                } else { p1 = ~0U; s0 = ss2; }
                arg1 = compile(s0,ve1,depth1,0,block_flags); // Offset
                _cimg_mp_check_type(arg1,0,1,0);
                arg2 = compile(s + 1,se,depth1,0,block_flags); // Value to assign
                _cimg_mp_check_type(arg2,2,*ss>='i'?1:3,0);
                if (is_vector(arg2)) {
                  if (p1!=~0U) {
                    _cimg_mp_check_const_index(p1);
                    p3 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
                    p2 = imglist[p3]._spectrum;
                  } else p2 = imgin._spectrum;
                  if (!p2) _cimg_mp_return(0);
                  _cimg_mp_check_type(arg2,2,2,p2);
                } else p2 = 0;

                if (p_ref) {
                  *p_ref = *ss=='I' || *ss=='J'?4:2;
                  p_ref[1] = p1;
                  p_ref[2] = (unsigned int)is_relative;
                  p_ref[3] = arg1;
                  if (is_vector(arg2)) set_reserved_vector(arg2); // Prevent from being used in further optimization
                  else if (is_comp_scalar(arg2)) memtype[arg2] = -1;
                  if (is_comp_scalar(arg1)) memtype[arg1] = -1;
                }

                if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                  if (*ss>='i')
                    CImg<ulongT>::vector((ulongT)mp_set_ijoff,arg2,(ulongT)is_relative,
                                         p1,arg1).move_to(code);
                  else if (is_scalar(arg2))
                    CImg<ulongT>::vector((ulongT)mp_set_IJoff_s,arg2,(ulongT)is_relative,
                                         p1,arg1).move_to(code);
                  else
                    CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg2,(ulongT)is_relative,
                                         p1,arg1,size(arg2)).move_to(code);
                }
                _cimg_mp_return(arg2);
              }

              if (*ss1=='(' && *ve1==')') { // i/j/I/J(_#ind,_x,_y,_z,_c) = value
                if (!is_inside_critical) is_parallelizable = false;
                if (*ss2=='#') { // Index specified
                  s0 = ss3; while (s0<ve1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                  p1 = compile(ss3,s0++,depth1,0,block_flags);
                  _cimg_mp_check_notnan_index(p1,ss3);
                  _cimg_mp_check_list();
                } else { p1 = ~0U; s0 = ss2; }
                arg1 = is_relative?0U:(unsigned int)_cimg_mp_slot_x;
                arg2 = is_relative?0U:(unsigned int)_cimg_mp_slot_y;
                arg3 = is_relative?0U:(unsigned int)_cimg_mp_slot_z;
                arg4 = is_relative?0U:(unsigned int)_cimg_mp_slot_c;
                arg5 = compile(s + 1,se,depth1,0,block_flags); // Value to assign
                _cimg_mp_check_type(arg5,2,*ss>='i'?1:3,0);
                if (s0<ve1) { // X or [ X,_Y,_Z,_C ]
                  s1 = s0; while (s1<ve1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg1 = compile(s0,s1,depth1,0,block_flags);
                  if (is_vector(arg1)) { // Coordinates specified as a vector
                    p2 = size(arg1); // Vector size
                    ++arg1;
                    if (p2>1) {
                      arg2 = arg1 + 1;
                      if (p2>2) {
                        arg3 = arg2 + 1;
                        if (p2>3) arg4 = arg3 + 1;
                      }
                    }
                  } else if (s1<ve1) { // Y
                    s2 = ++s1; while (s2<ve1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg2 = compile(s1,s2,depth1,0,block_flags);
                    if (s2<ve1) { // Z
                      s3 = ++s2; while (s3<ve1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                      arg3 = compile(s2,s3,depth1,0,block_flags);
                      if (s3<ve1) arg4 = compile(++s3,ve1,depth1,0,block_flags); // C
                    }
                  }
                }

                if (is_vector(arg5)) {
                  if (p1!=~0U) {
                    _cimg_mp_check_const_index(p1);
                    p3 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
                    p2 = imglist[p3]._spectrum;
                  } else p2 = imgin._spectrum;
                  if (!p2) _cimg_mp_return(0);
                  _cimg_mp_check_type(arg5,2,2,p2);
                } else p2 = 0;


                if (p_ref) {
                  *p_ref = *ss=='I' || *ss=='J'?5:3;
                  p_ref[1] = p1;
                  p_ref[2] = (unsigned int)is_relative;
                  p_ref[3] = arg1;
                  p_ref[4] = arg2;
                  p_ref[5] = arg3;
                  p_ref[6] = arg4;
                  if (is_vector(arg5)) set_reserved_vector(arg5); // Prevent from being used in further optimization
                  else if (is_comp_scalar(arg5)) memtype[arg5] = -1;
                  if (p1!=~0U && is_comp_scalar(p1)) memtype[p1] = -1;
                  if (is_comp_scalar(arg1)) memtype[arg1] = -1;
                  if (is_comp_scalar(arg2)) memtype[arg2] = -1;
                  if (is_comp_scalar(arg3)) memtype[arg3] = -1;
                  if (is_comp_scalar(arg4)) memtype[arg4] = -1;
                }

                if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                  if (*ss>='i')
                    CImg<ulongT>::vector((ulongT)mp_set_ijxyzc,arg5,(ulongT)is_relative,
                                         p1,arg1,arg2,arg3,arg4).move_to(code);
                  else if (is_scalar(arg5))
                    CImg<ulongT>::vector((ulongT)mp_set_IJxyz_s,arg5,(ulongT)is_relative,
                                         p1,arg1,arg2,arg3).move_to(code);
                  else
                    CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg5,(ulongT)is_relative,
                                         p1,arg1,arg2,arg3,size(arg5)).move_to(code);
                }
                _cimg_mp_return(arg5);
              }
            }

            // Assign vector value (direct).
            if (l_variable_name>3 && *ve1==']' && *ss!='[') {
              s0 = ve1; while (s0>ss && (*s0!='[' || level[s0 - expr._data]!=clevel)) --s0;
              if (s0>ss && cimg::is_varname(ss,s0 - ss)) {
                variable_name[s0 - ss] = 0; // Remove brackets in variable name
                if (*variable_name=='_' && (variable_name[1]=='0' || variable_name[1]=='1') &&
                    !variable_name[2]) // Force '_0' and '_1' to be allocated
                  arg1 = compile(ss,s0,depth1,0,block_flags);
                else {
                  get_variable_pos(variable_name,arg1,arg2);
                  arg1 = arg2!=~0U?reserved_label[arg2]:arg1!=~0U?variable_pos[arg1]:~0U; // Vector slot
                }

                if (arg1==~0U || is_scalar(arg1))
                  compile(ss,s0,depth1,0,block_flags); // Variable does not exist or is not a vector -> error

                arg2 = compile(++s0,ve1,depth1,0,block_flags); // Index
                arg3 = compile(s + 1,se,depth1,0,block_flags); // Value to assign
                _cimg_mp_check_type(arg3,2,1,0);

                if (is_const_scalar(arg2)) { // Constant index -> return corresponding variable slot directly
                  nb = (int)mem[arg2];
                  if (nb>=0 && nb<(int)size(arg1)) {
                    arg1+=nb + 1;
                    CImg<ulongT>::vector((ulongT)mp_copy,arg1,arg3).move_to(code);
                    _cimg_mp_return(arg1);
                  }
                  compile(ss,s,depth1,0,block_flags); // Out-of-bounds reference -> error
                }

                // Case of non-constant index -> return assigned value + linked reference.
                if (p_ref) {
                  *p_ref = 1;
                  p_ref[1] = arg1;
                  p_ref[2] = arg2;
                  if (is_comp_scalar(arg3)) memtype[arg3] = -1; // Prevent from being used in further optimization
                  if (is_comp_scalar(arg2)) memtype[arg2] = -1;
                }
                CImg<ulongT>::vector((ulongT)mp_vector_set_off,arg3,arg1,(ulongT)size(arg1),arg2).
                  move_to(code);
                _cimg_mp_return(arg3);
              }
            }

            // Assign user-defined macro.
            if (l_variable_name>2 && *ve1==')' && *ss!='(') {
              s0 = ve1; while (s0>ss && *s0!='(') --s0;
              if (cimg::is_varname(ss,s0 - ss) && std::strncmp(variable_name,"debug(",6) &&
                  std::strncmp(variable_name,"print(",6)) { // Valid macro name
                s0 = variable_name._data + (s0 - ss);
                *s0 = 0;
                s1 = variable_name._data + l_variable_name - 1; // Pointer to closing parenthesis
                CImg<charT>(variable_name._data,(unsigned int)(s0 - variable_name._data + 1)).move_to(macro_def,0);
                ++s; while (*s && cimg::is_blank(*s)) ++s;
                CImg<charT>(s,(unsigned int)(se - s + 1)).move_to(macro_body,0);

                bool is_variadic = false;
                p1 = 1; // Index of current parsed argument
                for (s = s0 + 1; s<=s1; ++p1, s = ns + 1) { // Parse function arguments
                  if (is_variadic && p1>1) {
                    _cimg_mp_strerr;
                    cimg::strellipsize(variable_name,64);
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Multiple arguments not allowed when first one is "
                                                "variadic, in macro definition '%s()', in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                variable_name._data,s0);
                  }
                  if (p1>24) {
                    _cimg_mp_strerr;
                    cimg::strellipsize(variable_name,64);
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Too many specified arguments (>24), in macro "
                                                "definition '%s()', in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                variable_name._data,s0);
                  }
                  while (*s && cimg::is_blank(*s)) ++s;
                  if (*s==')' && p1==1) break; // Function has no arguments
                  s2 = s; // Start of the argument name
                  is_sth = true; // is_valid_argument_name?
                  if (*s2>='0' && *s2<='9') is_sth = false;
                  else for (ns = s2; ns<s1 && *ns!=',' && *ns!='.' && !cimg::is_blank(*ns); ++ns)
                         if (!cimg::is_varchar(*ns)) { is_sth = false; break; }
                  s3 = ns; // End of the argument name
                  if (is_sth && ns>s2 && *ns=='.' && ns[1]=='.' && ns[2]=='.') { is_variadic = true; ns+=3; }
                  else if (*ns=='.') is_sth = false;
                  while (*ns && cimg::is_blank(*ns)) ++ns;

                  if (!is_sth || s2==s3 || (*ns!=',' && ns!=s1)) {
                    cimg::strellipsize(variable_name,64);
                    _cimg_mp_strerr;
                    if (is_sth)
                      throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                  "CImg<%s>::%s: %s: Empty argument name for argument %u of "
                                                  "macro '%s()', in expression '%s'.",
                                                  pixel_type(),_cimg_mp_calling_function,s_op,p1,
                                                  variable_name._data,s0);
                    else {
                      for (s3 = s2; *s3 && *s3!=',' && *s3!=')'; ++s3) {}
                      CImg<charT> argument_name(s2,s3 - s2 + 1); argument_name.back() = 0;
                      throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                  "CImg<%s>::%s: %s: Invalid argument name '%s' for argument %u of "
                                                  "macro '%s()', in expression '%s'.",
                                                  pixel_type(),_cimg_mp_calling_function,s_op,argument_name._data,p1,
                                                  variable_name._data,s0);
                    }
                  }

                  if (ns==s1 || *ns==',' || (is_variadic && *ns=='.')) { // New argument found
                    *s3 = 0;
                    p2 = (unsigned int)(s3 - s2); // Argument length
                    for (ps = std::strstr(macro_body[0],s2); ps; ps = std::strstr(ps,s2)) { // Replace by arg number
                      if (!((ps>macro_body[0]._data && cimg::is_varchar(*(ps - 1))) ||
                            (ps + p2<macro_body[0].end() && cimg::is_varchar(*(ps + p2))))) {
                        if (ps>macro_body[0]._data && *(ps - 1)=='#') { // Remove pre-number sign
                          *(ps - 1) = (char)p1;
                          if (ps + p2<macro_body[0].end() && *(ps + p2)=='#') { // Has pre & post number signs
                            std::memmove(ps,ps + p2 + 1,macro_body[0].end() - ps - p2 - 1);
                            macro_body[0]._width-=p2 + 1;
                          } else { // Has pre number sign only
                            std::memmove(ps,ps + p2,macro_body[0].end() - ps - p2);
                            macro_body[0]._width-=p2;
                          }
                        } else if (ps + p2<macro_body[0].end() && *(ps + p2)=='#') { // Remove post-number sign
                          *(ps++) = (char)p1;
                          std::memmove(ps,ps + p2,macro_body[0].end() - ps - p2);
                          macro_body[0]._width-=p2;
                        } else if (is_variadic) { // Replace variadic argument
                          *(ps++) = (char)p1;
                          std::memmove(ps,ps + p2 - 1,macro_body[0].end() - ps - p2 + 1);
                          macro_body[0]._width-=p2 - 1;
                        } else { // Not near a number sign
                          if (p2<3) {
                            ps-=(ulongT)macro_body[0]._data;
                            macro_body[0].resize(macro_body[0]._width - p2 + 3,1,1,1,0);
                            ps+=(ulongT)macro_body[0]._data;
                          } else macro_body[0]._width-=p2 - 3;
                          std::memmove(ps + 3,ps + p2,macro_body[0].end() - ps - 3);
                          *(ps++) = '(';
                          *(ps++) = (char)p1;
                          *(ps++) = ')';
                        }
                      } else ++ps;
                    }
                  }
                }

                // Store number of arguments.
                macro_def[0].resize(macro_def[0]._width + 1,1,1,1,0).back() = is_variadic?(char)-1:(char)(p1 - 1);
                _cimg_mp_return_nan();
              }
            }

            // Check if the variable name could be valid. If not, this is probably an lvalue assignment.
            const bool is_const = l_variable_name>6 && !std::strncmp(variable_name,"const ",6);
            s0 = variable_name._data;
            if (is_const) {
              s0+=6; while (cimg::is_blank(*s0)) ++s0;
              variable_name.resize(variable_name.end() - s0,1,1,1,0,0,1);
            }

            if (cimg::is_varname(variable_name)) { // Valid variable name

              // Assign variable (direct).
              get_variable_pos(variable_name,arg1,arg2);
              arg1 = arg2!=~0U?reserved_label[arg2]:arg1!=~0U?variable_pos[arg1]:~0U;
              arg3 = compile(s + 1,se,depth1,0,block_flags|(arg1==~0U?32:0));
              is_sth = return_comp; // is arg3 a new blank object?
              if (is_const) _cimg_mp_check_const_scalar(arg3,2,0);

              if (arg1==~0U) { // Create new variable
                if (is_vector(arg3)) { // Vector variable
                  arg1 = is_sth || is_comp_vector(arg3)?arg3:copy(arg3);
                  set_reserved_vector(arg1); // Prevent from being used in further optimization
                } else { // Scalar variable
                  if (is_const) arg1 = arg3;
                  else {
                    arg1 = is_sth || is_comp_scalar(arg3)?arg3:scalar1(mp_copy,arg3);
                    memtype[arg1] = -1;
                  }
                }

                if (arg2!=~0U) reserved_label[arg2] = arg1;
                else {
                  if (variable_def._width>=variable_pos._width) variable_pos.resize(-200,1,1,1,0);
                  variable_pos[variable_def._width] = arg1;
                  variable_name.move_to(variable_def);
                }

              } else { // Variable already exists -> assign a new value
                if (is_const || is_const_scalar(arg1)) {
                  cimg::strellipsize(variable_name,64);
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Invalid assignment of %sconst variable '%s'%s, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              is_const_scalar(arg1)?"":"non-",
                                              variable_name._data,
                                              !is_const_scalar(arg1) && is_const?" as a const variable":"",
                                              s0);
                }
                _cimg_mp_check_type(arg3,2,is_vector(arg1)?3:1,size(arg1));
                if (is_vector(arg1)) { // Vector
                  if (is_vector(arg3)) { // From vector
                    if (arg1!=arg3) {
                      CImg<ulongT> &pop = code.back();
                      mp_func fn = (mp_func)pop[0];
                      if ((fn==mp_cumulate || fn==mp_equalize || fn==mp_mirror || fn==mp_noise || fn==mp_normalize ||
                           fn==mp_permute || fn==mp_reverse || fn==mp_shift || fn==mp_sort) &&
                          pop[1]==arg3 && pop[2]==arg1) {
                        // Spot cases 'X = func(X)' -> call in-place version of 'func()'.
                        pop[0] = (ulongT)(fn==mp_cumulate?mp_cumulate_ip:
                                          fn==mp_equalize?mp_equalize_ip:
                                          fn==mp_mirror?mp_mirror_ip:
                                          fn==mp_noise?mp_noise_ip:
                                          fn==mp_normalize?mp_normalize_ip:
                                          fn==mp_permute?mp_permute_ip:
                                          fn==mp_reverse?mp_reverse_ip:
                                          fn==mp_shift?mp_shift_ip:
                                          mp_sort_ip);
                        pop[1] = (ulongT)_cimg_mp_slot_nan;
                        if (mempos==arg3 + size(arg3) + 1) {
                          mempos-=size(arg3) + 1;
                          std::memset(&memtype[mempos],0,sizeof(int)*size(arg3) + 1);
                        }
                      } else {
                        is_sth = is_comp_vector(arg3) && pop[1]==arg3 &&
                          fn!=mp_set_IJoff_v && fn!=mp_set_IJxyz_v;
                        if (is_sth)
                          for (unsigned int k = 2; k<pop.size(); ++k) if (pop[k]==arg3) { is_sth = false; break; }
                        if (is_sth) {
                          // Spot case 'X = f(...)' -> make 'f()' write directly into variable slot.
                          pop[1] = arg1;
                          if (mempos==arg3 + size(arg3) + 1) {
                            mempos-=size(arg3) + 1;
                            std::memset(&memtype[mempos],0,sizeof(int)*size(arg3) + 1);
                          }
                        } else
                          CImg<ulongT>::vector((ulongT)mp_vector_copy,arg1,arg3,(ulongT)size(arg1)).
                            move_to(code);
                      }
                    }
                  } else // From scalar
                    CImg<ulongT>::vector((ulongT)mp_vector_init,arg1,(ulongT)size(arg1),1,arg3,0).
                      move_to(code);
                } else { // Scalar
                  if (arg1!=arg3) {
                    CImg<ulongT> &pop = code.back();
                    mp_func fn = (mp_func)pop[0];
                    is_sth = is_comp_scalar(arg3) && pop[1]==arg3 &&
                      fn!=mp_set_ijoff && fn!=mp_set_ijxyzc && fn!=mp_set_IJoff_s && fn!=mp_set_IJxyz_s;
                    if (is_sth)
                      for (unsigned int k = 2; k<pop.size(); ++k) if (pop[k]==arg3) { is_sth = false; break; }
                    if (is_sth) {
                      // Spot case 'x = f(...)' -> make 'f()' write directly into variable slot.
                      pop[1] = arg1;
                      if (mempos==arg3 + 1) memtype[--mempos] = 0;
                    } else
                      CImg<ulongT>::vector((ulongT)mp_copy,arg1,arg3).move_to(code);
                  }
                }
              }
              return_comp = false;
              _cimg_mp_return(arg1);
            }

            // Assign lvalue (the variable name was not valid for a direct assignment).
            arg1 = ~0U;
            is_sth = (bool)std::strchr(variable_name,'?'); // Contains_ternary_operator?
            if (is_sth) break; // Do nothing and make ternary operator priority over assignment

            if (l_variable_name>2 && (std::strchr(variable_name,'(') || std::strchr(variable_name,'['))) {
              ref.assign(7);
              arg1 = compile(ss,s,depth1,ref,block_flags); // Lvalue slot
              arg2 = compile(s + 1,se,depth1,0,block_flags); // Value to assign

              if (*ref==1) { // Vector value (scalar): (V[k]) = scalar
                _cimg_mp_check_type(arg2,2,1,0);
                arg3 = ref[1]; // Vector slot
                arg4 = ref[2]; // Index
                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
                CImg<ulongT>::vector((ulongT)mp_vector_set_off,arg2,arg3,(ulongT)size(arg3),arg4).
                  move_to(code);
                _cimg_mp_return(arg2);
              }

              if (*ref==2) { // Image value (scalar): (i/j[_#ind,off]) = scalar
                if (!is_inside_critical) is_parallelizable = false;
                _cimg_mp_check_type(arg2,2,1,0);
                p1 = ref[1]; // Index
                is_relative = (bool)ref[2];
                arg3 = ref[3]; // Offset
                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
                if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                  CImg<ulongT>::vector((ulongT)mp_set_ijoff,arg2,(ulongT)is_relative,
                                       p1,arg3).move_to(code);
                _cimg_mp_return(arg2);
              }

              if (*ref==3) { // Image value (scalar): (i/j(_#ind,_x,_y,_z,_c)) = scalar
                if (!is_inside_critical) is_parallelizable = false;
                _cimg_mp_check_type(arg2,2,1,0);
                p1 = ref[1]; // Index
                is_relative = (bool)ref[2];
                arg3 = ref[3]; // X
                arg4 = ref[4]; // Y
                arg5 = ref[5]; // Z
                arg6 = ref[6]; // C
                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
                if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                  CImg<ulongT>::vector((ulongT)mp_set_ijxyzc,arg2,(ulongT)is_relative,
                                       p1,arg3,arg4,arg5,arg6).move_to(code);
                _cimg_mp_return(arg2);
              }

              if (*ref==4) { // Image value (vector): (I/J[_#ind,off]) = value
                if (!is_inside_critical) is_parallelizable = false;
                _cimg_mp_check_type(arg2,2,3,size(arg1));
                p1 = ref[1]; // Index
                is_relative = (bool)ref[2];
                arg3 = ref[3]; // Offset
                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
                if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                  if (is_scalar(arg2))
                    CImg<ulongT>::vector((ulongT)mp_set_IJoff_s,arg2,(ulongT)is_relative,
                                         p1,arg3).move_to(code);
                  else {
                    _cimg_mp_check_const_index(p1);
                    CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg2,(ulongT)is_relative,
                                         p1,arg3,size(arg2)).move_to(code);
                  }
                }
                _cimg_mp_return(arg2);
              }

              if (*ref==5) { // Image value (vector): (I/J(_#ind,_x,_y,_z,_c)) = value
                if (!is_inside_critical) is_parallelizable = false;
                _cimg_mp_check_type(arg2,2,3,size(arg1));
                p1 = ref[1]; // Index
                is_relative = (bool)ref[2];
                arg3 = ref[3]; // X
                arg4 = ref[4]; // Y
                arg5 = ref[5]; // Z
                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
                if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                  if (is_scalar(arg2))
                    CImg<ulongT>::vector((ulongT)mp_set_IJxyz_s,arg2,(ulongT)is_relative,
                                         p1,arg3,arg4,arg5).move_to(code);
                  else {
                    _cimg_mp_check_const_index(p1);
                    CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg2,(ulongT)is_relative,
                                         p1,arg3,arg4,arg5,size(arg2)).move_to(code);
                  }
                }
                _cimg_mp_return(arg2);
              }

              if (is_vector(arg1)) { // Vector variable: (V) = value
                _cimg_mp_check_type(arg2,2,3,size(arg1));
                if (is_vector(arg2)) { // From vector
                  if (arg1!=arg2) {
                    CImg<ulongT> &pop = code.back();
                    mp_func fn = (mp_func)pop[0];
                    if ((fn==mp_cumulate || fn==mp_equalize || fn==mp_mirror || fn==mp_noise || fn==mp_normalize ||
                         fn==mp_permute || fn==mp_reverse || fn==mp_shift || fn==mp_sort) &&
                        pop[1]==arg2 && pop[2]==arg1) {
                      // Spot cases 'X = func(X)' -> call in-place version of 'func()'.
                      pop[0] = (ulongT)(fn==mp_cumulate?mp_cumulate_ip:
                                        fn==mp_equalize?mp_equalize_ip:
                                        fn==mp_mirror?mp_mirror_ip:
                                        fn==mp_noise?mp_noise_ip:
                                        fn==mp_normalize?mp_normalize_ip:
                                        fn==mp_permute?mp_permute_ip:
                                        fn==mp_reverse?mp_reverse_ip:
                                        fn==mp_shift?mp_shift_ip:
                                        mp_sort_ip);
                      pop[1] = (ulongT)_cimg_mp_slot_nan;
                      if (mempos==arg2 + size(arg2) + 1) {
                        mempos-=size(arg2) + 1;
                        std::memset(&memtype[mempos],0,sizeof(int)*size(arg2) + 1);
                      }
                    } else {
                      is_sth = is_comp_vector(arg2) && pop[1]==arg2 &&
                        fn!=mp_set_IJoff_v && fn!=mp_set_IJxyz_v;
                      if (is_sth)
                        for (unsigned int k = 2; k<pop.size(); ++k) if (pop[k]==arg2) { is_sth = false; break; }
                      if (is_sth) {
                        // Spot case '(X) = f(...)' -> make 'f()' write directly into variable slot.
                        pop[1] = arg1;
                        if (mempos==arg2 + size(arg2) + 1) {
                          mempos-=size(arg2) + 1;
                          std::memset(&memtype[mempos],0,sizeof(int)*size(arg2) + 1);
                        }
                      } else
                        CImg<ulongT>::vector((ulongT)mp_vector_copy,arg1,arg2,(ulongT)size(arg1)).
                          move_to(code);
                    }
                  }
                } else // From scalar
                  CImg<ulongT>::vector((ulongT)mp_vector_init,arg1,(ulongT)size(arg1),1,arg2,0).
                    move_to(code);
                return_comp = false;
                _cimg_mp_return(arg1);
              }

              if (is_reserved(arg1) && arg1>_cimg_mp_slot_c) { // Scalar variable: (s) = scalar
                _cimg_mp_check_type(arg2,2,1,0);
                if (arg1!=arg2) {
                  CImg<ulongT> &pop = code.back();
                  mp_func fn = (mp_func)pop[0];
                  is_sth = is_comp_scalar(arg2) && pop[1]==arg2 &&
                    fn!=mp_set_ijoff && fn!=mp_set_ijxyzc && fn!=mp_set_IJoff_s && fn!=mp_set_IJxyz_s;
                  if (is_sth)
                    for (unsigned int k = 2; k<pop.size(); ++k) if (pop[k]==arg2) { is_sth = false; break; }
                  if (is_sth) {
                    // Spot case '(x) = f(...)' -> make 'f()' write directly into variable slot.
                    pop[1] = arg1;
                    if (mempos==arg2 + 1) memtype[--mempos] = 0;
                  } else
                    CImg<ulongT>::vector((ulongT)mp_copy,arg1,arg2).move_to(code);
                }
                return_comp = false;
                _cimg_mp_return(arg1);
              }
            }

            // No assignment expressions match -> error.
            cimg::strellipsize(variable_name,64);
            _cimg_mp_strerr;
            throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                        "CImg<%s>::%s: %s: Invalid %slvalue '%s', "
                                        "in expression '%s'.",
                                        pixel_type(),_cimg_mp_calling_function,s_op,
                                        arg1!=~0U && is_const_scalar(arg1)?"const ":"",
                                        variable_name._data,s0);
          }
        }

        // Apply unary/binary/ternary operators. The operator precedences should be the same as in C++.
        is_sth = true;
        for (s = ss; s<se1; ++s) // Do a first pass to quickly skip costly operator checks that require for() loop
          if (cimg::_cimg_math_parser_check_operator[(unsigned char)*s] && level[s - expr._data]==clevel) {
            is_sth = false; break;
          }
        if (is_sth) goto cimg_skip_iterative_operator_parsing;

        for (s = se2, ps = se3, ns = ps - 1; s>ss1; --s, --ps, --ns) // Here, ns = ps - 1
          if (*s=='=' && (*ps=='*' || *ps=='/' || *ps=='^') && *ns==*ps &&
              level[s - expr._data]==clevel) { // Self-operators for complex numbers only (**=,//=,^^=)
            _cimg_mp_op(*ps=='*'?"Operator '**='":*ps=='/'?"Operator '//='":"Operator '^^='");

            ref.assign(7);
            arg1 = compile(ss,ns,depth1,ref,block_flags); // Vector slot
            arg2 = compile(s + 1,se,depth1,0,block_flags); // Right operand
            _cimg_mp_check_type(arg1,1,2,2);
            _cimg_mp_check_type(arg2,2,3,2);
            if (is_vector(arg2)) { // Complex **= complex
              if (*ps=='*')
                CImg<ulongT>::vector((ulongT)mp_complex_mul,arg1,arg1,arg2).move_to(code);
              else if (*ps=='/')
                CImg<ulongT>::vector((ulongT)mp_complex_div_vv,arg1,arg1,arg2).move_to(code);
              else
                CImg<ulongT>::vector((ulongT)mp_complex_pow_vv,arg1,arg1,arg2).move_to(code);
            } else { // Complex **= scalar
              if (arg2==1) _cimg_mp_return(arg1);
              if (*ps=='*') _cimg_mp_self_vector2(mp_self_vector_mul_s,arg1,arg2);
              else if (*ps=='/') _cimg_mp_self_vector2(mp_self_vector_div_s,arg1,arg2);
              else if (arg2==2) CImg<ulongT>::vector((ulongT)mp_complex_sqr,arg1,2,arg1).move_to(code);
              else CImg<ulongT>::vector((ulongT)mp_complex_pow_vs,arg1,arg1,arg2).move_to(code);
            }

            if (*ref==4) { // Image value (vector): I/J[_#ind,off] **= value
              if (!is_inside_critical) is_parallelizable = false;
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // Offset
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                if (p1!=~0U) _cimg_mp_check_const_index(p1);
                CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg1,(ulongT)is_relative,
                                     p1,arg3,size(arg1)).move_to(code);
              }
            } else if (*ref==5) { // Image value (vector): I/J(_#ind,_x,_y,_z,_c) **= value
              if (!is_inside_critical) is_parallelizable = false;
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // X
              arg4 = ref[4]; // Y
              arg5 = ref[5]; // Z
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                if (p1!=~0U) _cimg_mp_check_const_index(p1);
                CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg1,(ulongT)is_relative,
                                     p1,arg3,arg4,arg5,size(arg1)).move_to(code);
              }
            }
            _cimg_mp_return(arg1);
          }

        for (s = se2, ps = se3, ns = ps - 1; s>ss1; --s, --ps, --ns) // Here, ns = ps - 1
          if (*s=='=' && (*ps=='+' || *ps=='-' || *ps=='*' || *ps=='/' || (*ps=='%' && s[1]!='=') ||
                          *ps=='&' || *ps=='^' || *ps=='|' ||
                          (*ps=='>' && *ns=='>') || (*ps=='<' && *ns=='<')) &&
              level[s - expr._data]==clevel) { // Self-operators (+=,-=,*=,/=,%=,>>=,<<=,&=,^=,|=)
            mp_func op_s, op_v;
            switch (*ps) {
            case '+' :
              op = mp_self_add;
              op_s = mp_self_vector_add_s; op_v = mp_self_vector_add_v;
              _cimg_mp_op("Operator '+='");
              break;
            case '-' :
              op = mp_self_sub;
              op_s = mp_self_vector_sub_s; op_v = mp_self_vector_sub_v;
              _cimg_mp_op("Operator '-='");
              break;
            case '*' :
              op = mp_self_mul;
              op_s = mp_self_vector_mul_s; op_v = mp_self_vector_mul_v;
              _cimg_mp_op("Operator '*='");
              break;
            case '/' :
              op = mp_self_div;
              op_s = mp_self_vector_div_s; op_v = mp_self_vector_div_v;
              _cimg_mp_op("Operator '/='");
              break;
            case '%' :
              op = mp_self_modulo;
              op_s = mp_self_vector_modulo_s; op_v = mp_self_vector_modulo_v;
              _cimg_mp_op("Operator '%='");
              break;
            case '<' :
              op = mp_self_bitwise_left_shift;
              op_s = mp_self_vector_bitwise_left_shift_s; op_v = mp_self_vector_bitwise_left_shift_v;
              _cimg_mp_op("Operator '<<='");
              break;
            case '>' :
              op = mp_self_bitwise_right_shift;
              op_s = mp_self_vector_bitwise_right_shift_s; op_v = mp_self_vector_bitwise_right_shift_v;
              _cimg_mp_op("Operator '>>='");
              break;
            case '&' :
              op = mp_self_bitwise_and;
              op_s = mp_self_vector_bitwise_and_s; op_v = mp_self_vector_bitwise_and_v;
              _cimg_mp_op("Operator '&='");
              break;
            case '|' :
              op = mp_self_bitwise_or;
              op_s = mp_self_vector_bitwise_or_s; op_v = mp_self_vector_bitwise_or_v;
              _cimg_mp_op("Operator '|='");
              break;
            default :
              op = mp_self_pow;
              op_s = mp_self_vector_pow_s; op_v = mp_self_vector_pow_v;
              _cimg_mp_op("Operator '^='");
              break;
            }
            s1 = *ps=='>' || *ps=='<'?ns:ps;

            ref.assign(7);
            arg1 = compile(ss,s1,depth1,ref,block_flags); // Variable slot
            arg2 = compile(s + 1,se,depth1,0,block_flags); // Value to apply

            // Check for particular case to be simplified.
            if ((op==mp_self_add || op==mp_self_sub) && !arg2) _cimg_mp_return(arg1);
            if ((op==mp_self_mul || op==mp_self_div || op==mp_self_pow) && arg2==1) _cimg_mp_return(arg1);
            if (op==mp_self_pow && (arg2==0 || arg2==2)) {
              if (!arg2) CImg<ulongT>::vector((ulongT)mp_copy,arg1,1).move_to(code);
              else CImg<ulongT>::vector((ulongT)mp_sqr,arg1,arg1).move_to(code);
              _cimg_mp_return(arg1);
            }

            if (*ref==1) { // Vector value (scalar): V[k] += scalar
              _cimg_mp_check_type(arg2,2,1,0);
              arg3 = ref[1]; // Vector slot
              arg4 = ref[2]; // Index
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              CImg<ulongT>::vector((ulongT)op,arg1,arg2).move_to(code);
              CImg<ulongT>::vector((ulongT)mp_vector_set_off,arg1,arg3,(ulongT)size(arg3),arg4).
                move_to(code);
              _cimg_mp_return(arg1);
            }

            if (*ref==2) { // Image value (scalar): i/j[_#ind,off] += scalar
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_check_type(arg2,2,1,0);
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // Offset
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              CImg<ulongT>::vector((ulongT)op,arg1,arg2).move_to(code);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                CImg<ulongT>::vector((ulongT)mp_set_ijoff,arg1,(ulongT)is_relative,
                                     p1,arg3).move_to(code);
              _cimg_mp_return(arg1);
            }

            if (*ref==3) { // Image value (scalar): i/j(_#ind,_x,_y,_z,_c) += scalar
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_check_type(arg2,2,1,0);
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // X
              arg4 = ref[4]; // Y
              arg5 = ref[5]; // Z
              arg6 = ref[6]; // C
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              CImg<ulongT>::vector((ulongT)op,arg1,arg2).move_to(code);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                CImg<ulongT>::vector((ulongT)mp_set_ijxyzc,arg1,(ulongT)is_relative,
                                     p1,arg3,arg4,arg5,arg6).move_to(code);
              _cimg_mp_return(arg1);
            }

            if (*ref==4) { // Image value (vector): I/J[_#ind,off] += value
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_check_type(arg2,2,3,size(arg1));
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // Offset
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              _cimg_mp_self_vector2(is_scalar(arg2)?op_s:op_v,arg1,arg2);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg1,(ulongT)is_relative,
                                     p1,arg3,size(arg1)).move_to(code);
              _cimg_mp_return(arg1);
            }

            if (*ref==5) { // Image value (vector): I/J(_#ind,_x,_y,_z,_c) += value
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_check_type(arg2,2,3,size(arg1));
              p1 = ref[1]; // Index
              is_relative = (bool)ref[2];
              arg3 = ref[3]; // X
              arg4 = ref[4]; // Y
              arg5 = ref[5]; // Z
              if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              _cimg_mp_self_vector2(is_scalar(arg2)?op_s:op_v,arg1,arg2);
              if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg1,(ulongT)is_relative,
                                     p1,arg3,arg4,arg5,size(arg1)).move_to(code);
              _cimg_mp_return(arg1);
            }

            if (is_vector(arg1)) { // Vector variable: V += value
              _cimg_mp_check_type(arg2,2,3,size(arg1));
              _cimg_mp_self_vector2(is_scalar(arg2)?op_s:op_v,arg1,arg2);
              _cimg_mp_return(arg1);
            }

            if (is_reserved(arg1)) { // Scalar variable: s += scalar
              _cimg_mp_check_type(arg2,2,1,0);
              CImg<ulongT>::vector((ulongT)op,arg1,arg2).move_to(code);
              _cimg_mp_return(arg1);
            }

            variable_name.assign(ss,(unsigned int)(s - ss)).back() = 0;
            cimg::strpare(variable_name,false,true);
            cimg::strellipsize(variable_name,64);
            _cimg_mp_strerr;
            throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                        "CImg<%s>::%s: %s: Invalid %slvalue '%s', "
                                        "in expression '%s'.",
                                        pixel_type(),_cimg_mp_calling_function,s_op,
                                        is_const_scalar(arg1)?"const ":"",
                                        variable_name._data,s0);
          }

        for (s = ss1; s<se1; ++s)
          if (*s=='?' && level[s - expr._data]==clevel) { // Ternary operator 'cond?expr1:expr2'
            _cimg_mp_op("Operator '?:'");
            s1 = s + 1; while (s1<se1 && (*s1!=':' || level[s1 - expr._data]!=clevel)) ++s1;
            arg1 = compile(ss,s,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,1,0);
            if (is_const_scalar(arg1)) {
              if ((bool)mem[arg1]) return compile(s + 1,*s1!=':'?se:s1,depth1,0,block_flags);
              else return *s1!=':'?0:compile(++s1,se,depth1,0,block_flags);
            }
            p2 = code._width;
            arg2 = compile(s + 1,*s1!=':'?se:s1,depth1,0,block_flags);
            p3 = code._width;
            arg3 = *s1==':'?compile(++s1,se,depth1,0,block_flags):
              is_vector(arg2)?vector(size(arg2),0):0;
            _cimg_mp_check_type(arg3,3,is_vector(arg2)?2:1,size(arg2));
            arg4 = size(arg2);
            if (arg4) pos = vector(arg4); else pos = scalar();
            CImg<ulongT>::vector((ulongT)mp_if,pos,arg1,arg2,arg3,
                                 p3 - p2,code._width - p3,arg4).move_to(code,p2);
            return_comp = true;
            _cimg_mp_return(pos);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='|' && *ns=='|' && level[s - expr._data]==clevel) { // Logical or ('||')
            _cimg_mp_op("Operator '||'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,1,0);
            if (is_const_scalar(arg1) && mem[arg1]) _cimg_mp_return(1);
            p2 = code._width;
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,1,0);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1] || mem[arg2]);
            if (!arg1) _cimg_mp_scalar1(bool,arg2);
            pos = scalar();
            CImg<ulongT>::vector((ulongT)mp_logical_or,pos,arg1,arg2,code._width - p2).move_to(code,p2);
            return_comp = true;
            _cimg_mp_return(pos);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='&' && *ns=='&' && level[s - expr._data]==clevel) { // Logical and ('&&')
            _cimg_mp_op("Operator '&&'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,1,0);
            if (!arg1) _cimg_mp_return(0);
            p2 = code._width;
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,1,0);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1] && mem[arg2]);
            if (is_const_scalar(arg1) && mem[arg1]) _cimg_mp_scalar1(bool,arg2);
            pos = scalar();
            CImg<ulongT>::vector((ulongT)mp_logical_and,pos,arg1,arg2,code._width - p2).
              move_to(code,p2);
            return_comp = true;
            _cimg_mp_return(pos);
          }

        for (s = se2; s>ss; --s)
          if (*s=='|' && level[s - expr._data]==clevel) { // Bitwise or ('|')
            _cimg_mp_op("Operator '|'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) {
              if (!arg2) _cimg_mp_same(arg1);
              if (!arg1) _cimg_mp_same(arg2);
              _cimg_mp_vector2(bitwise_or,arg1,arg2);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar((longT)mem[arg1] | (longT)mem[arg2]);
            if (!arg2) _cimg_mp_same(arg1);
            if (!arg1) _cimg_mp_same(arg2);
            _cimg_mp_scalar2(bitwise_or,arg1,arg2);
          }

        for (s = se2; s>ss; --s)
          if (*s=='&' && level[s - expr._data]==clevel) { // Bitwise and ('&')
            _cimg_mp_op("Operator '&'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(bitwise_and,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar((longT)mem[arg1] & (longT)mem[arg2]);
            if (!arg1 || !arg2) _cimg_mp_return(0);
            _cimg_mp_scalar2(bitwise_and,arg1,arg2);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='!' && *ns=='=' && level[s - expr._data]==clevel) { // Not equal to ('!=')
            _cimg_mp_op("Operator '!='");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            if (arg1==arg2) _cimg_mp_return(0);
            p1 = size(arg1);
            p2 = size(arg2);
            if (p1 || p2) {
              if (p1 && p2 && p1!=p2) _cimg_mp_return(1);
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_vector_neq,pos,arg1,p1,arg2,p2,11,1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]!=mem[arg2]);
            _cimg_mp_scalar2(neq,arg1,arg2);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='=' && *ns=='=' && level[s - expr._data]==clevel) { // Equal to ('==')
            _cimg_mp_op("Operator '=='");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            if (arg1==arg2) _cimg_mp_return(1);
            p1 = size(arg1);
            p2 = size(arg2);
            if (p1 || p2) {
              if (p1 && p2 && p1!=p2) _cimg_mp_return(0);
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_vector_eq,pos,arg1,p1,arg2,p2,11,1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]==mem[arg2]);
            _cimg_mp_scalar2(eq,arg1,arg2);
          }

        for (s = se3, ns = se2, ps = se4; s>ss; --s, --ns)
          if (*s=='<' && *ns=='=' && *ps!='$' && level[s - expr._data]==clevel) { // Less than or equal to ('<=')
            _cimg_mp_op("Operator '<='");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(lte,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]<=mem[arg2]);
            if (arg1==arg2) _cimg_mp_return(1);
            _cimg_mp_scalar2(lte,arg1,arg2);
          }

        for (s = se3, ns = se2, ps = se4; s>ss; --s, --ns)
          if (*s=='>' && *ns=='=' && *ps!='$' && level[s - expr._data]==clevel) { // Greater than or equal to ('>=')
            _cimg_mp_op("Operator '>='");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(gte,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]>=mem[arg2]);
            if (arg1==arg2) _cimg_mp_return(1);
            _cimg_mp_scalar2(gte,arg1,arg2);
          }

        for (s = se2, ns = se1, ps = se3; s>ss; --s, --ns, --ps)
          if (*s=='<' && *ns!='<' && *ps!='<' && *ps!='$' && level[s - expr._data]==clevel) { // Less than ('<')
            _cimg_mp_op("Operator '<'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(lt,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]<mem[arg2]);
            if (arg1==arg2) _cimg_mp_return(0);
            _cimg_mp_scalar2(lt,arg1,arg2);
          }

        for (s = se2, ns = se1, ps = se3; s>ss; --s, --ns, --ps)
          if (*s=='>' && *ns!='>' && *ps!='>' && *ps!='$' && level[s - expr._data]==clevel) { // Greater than ('>')
            _cimg_mp_op("Operator '>'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(gt,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]>mem[arg2]);
            if (arg1==arg2) _cimg_mp_return(0);
            _cimg_mp_scalar2(gt,arg1,arg2);
          }

        for (s = se3, ns = se2, ps = se4; s>ss; --s, --ns)
          if (*s=='<' && *ns=='<' && *ps!='$' && level[s - expr._data]==clevel) { // Left bit shift ('<<')
            _cimg_mp_op("Operator '<<'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) {
              if (!arg2) _cimg_mp_same(arg1);
              _cimg_mp_vector2(bitwise_left_shift,arg1,arg2);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(cimg::bsl(mem[arg1],(int)mem[arg2]));
            if (!arg1) _cimg_mp_return(0);
            if (!arg2) _cimg_mp_same(arg1);
            _cimg_mp_scalar2(bitwise_left_shift,arg1,arg2);
          }

        for (s = se3, ns = se2, ps = se4; s>ss; --s, --ns)
          if (*s=='>' && *ns=='>' && *ps!='$' && level[s - expr._data]==clevel) { // Right bit shift ('>>')
            _cimg_mp_op("Operator '>>'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) {
              if (!arg2) _cimg_mp_same(arg1);
              _cimg_mp_vector2(bitwise_right_shift,arg1,arg2);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(cimg::bsr(mem[arg1],(int)mem[arg2]));
            if (!arg1) _cimg_mp_return(0);
            if (!arg2) _cimg_mp_same(arg1);
            _cimg_mp_scalar2(bitwise_right_shift,arg1,arg2);
          }

        for (s = se2, ns = se1, ps = pexpr._data + (se3 - expr._data); s>ss; --ns, --s, --ps)
          if (*s=='+' && (*ns!='+' || ns!=se1) && *ps!='-' && *ps!='+' && *ps!='*' && *ps!='/' && *ps!='%' &&
              *ps!='&' && *ps!='|' && *ps!='^' && *ps!='!' && *ps!='~' && *ps!='#' &&
              (*ps!='e' || !(ps - pexpr._data>ss - expr._data && (*(ps - 1)=='.' || (*(ps - 1)>='0' &&
                                                                                     *(ps - 1)<='9')))) &&
              level[s - expr._data]==clevel) { // Addition ('+')
            _cimg_mp_op("Operator '+'");
            p1 = p2 = ~0U;
            const ulongT *ptr1 = 0, *ptr2 = 0;
            p3 = code.size();
            arg1 = compile(ss,s,depth1,0,block_flags);

            // Spot cases '(a + b) + c', '(a - b) + c', '(a*b) + c' and '(a/b) + c'.
            if (is_scalar(arg1) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if ((op==mp_add || op==mp_sub || op==mp_mul || op==mp_div) && pop[1]==arg1) {
                p1 = code.size() - 1;
                ptr1 = pop.data();
              }
            }
            p3 = code.size();
            arg2 = compile(s + 1,se,depth1,0,block_flags);

            // Spot cases 'a + (b - c)', 'a + (b*c)' and 'a + (b/c)'.
            if (!ptr1 && is_scalar(arg2) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if ((op==mp_sub || op==mp_mul || op==mp_div) && pop[1]==arg2) {
                p2 = code.size() - 1;
                ptr2 = pop.data();
              }
            }
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (!arg2) _cimg_mp_same(arg1);
            if (!arg1) _cimg_mp_same(arg2);
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(add,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2)) _cimg_mp_const_scalar(mem[arg1] + mem[arg2]);
            if (p1<code.size() && code[p1].data()==ptr1 && ptr1[1]==(ulongT)arg1) {
              arg3 = (unsigned int)ptr1[2]; arg4 = (unsigned int)ptr1[3];
              op = (mp_func)*ptr1;
              code.remove(p1);
              if (op==mp_add) { // Particular case '(a + b) + c'
                if (is_const_scalar(arg2)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(add,arg4,const_scalar(mem[arg2] + mem[arg3]));
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(add,arg3,const_scalar(mem[arg2] + mem[arg4]));
                }
                _cimg_mp_scalar3(add_add,arg2,arg3,arg4);
              } else if (op==mp_sub) { // Particular case '(a - b) + c'
                if (is_const_scalar(arg2)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(sub,const_scalar(mem[arg2] + mem[arg3]),arg4);
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(add,arg3,const_scalar(mem[arg2] - mem[arg4]));
                }
                _cimg_mp_scalar3(add_sub,arg2,arg3,arg4);
              }
              else if (op==mp_mul) _cimg_mp_scalar3(add_mul,arg2,arg3,arg4); // Particular case '(a*b) + c'
              _cimg_mp_scalar3(div_add,arg3,arg4,arg2); // Particular case '(a/b) + c'
            }
            if (p2<code.size() && code[p2].data()==ptr2 && ptr2[1]==(ulongT)arg2) {
              arg3 = (unsigned int)ptr2[2]; arg4 = (unsigned int)ptr2[3];
              op = (mp_func)*ptr2;
              code.remove(p2);
              if (op==mp_sub) { // Particular case 'a + (b - c)'
                if (is_const_scalar(arg1)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(sub,const_scalar(mem[arg1] + mem[arg3]),arg4);
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(add,arg3,const_scalar(mem[arg1] - mem[arg4]));
                }
                _cimg_mp_scalar3(add_sub,arg1,arg3,arg4);
              } else if (op==mp_mul) _cimg_mp_scalar3(add_mul,arg1,arg3,arg4); // Particular case 'a + (b*c)'
              _cimg_mp_scalar3(div_add,arg3,arg4,arg1); // Particular case 'a + (b/c)'
            }
            if (arg2==1) _cimg_mp_scalar1(increment,arg1);
            if (arg1==1) _cimg_mp_scalar1(increment,arg2);
            _cimg_mp_scalar2(add,arg1,arg2);
          }

        for (s = se2, ns = se1, ps = pexpr._data + (se3 - expr._data); s>ss; --ns, --s, --ps)
          if (*s=='-' && (*ns!='-' || ns!=se1) && *ps!='-' && *ps!='+' && *ps!='*' && *ps!='/' && *ps!='%' &&
              *ps!='&' && *ps!='|' && *ps!='^' && *ps!='!' && *ps!='~' && *ps!='#' &&
              (*ps!='e' || !(ps - pexpr._data>ss - expr._data && (*(ps - 1)=='.' || (*(ps - 1)>='0' &&
                                                                                     *(ps - 1)<='9')))) &&
              level[s - expr._data]==clevel) { // Subtraction ('-')
            _cimg_mp_op("Operator '-'");
            p1 = p2 = ~0U;
            const ulongT *ptr1 = 0, *ptr2 = 0;
            p3 = code.size();
            arg1 = compile(ss,s,depth1,0,block_flags);

            // Spot cases '(a - b) - c', '(a*b) - c' and '(a/b) - c'.
            if (is_scalar(arg1) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if ((op==mp_sub || op==mp_mul || op==mp_div) && pop[1]==arg1) {
                p1 = code.size() - 1;
                ptr1 = pop.data();
              }
            }
            p3 = code.size();
            arg2 = compile(s + 1,se,depth1,0,block_flags);

            // Spot cases 'a - (b*c)' and 'a - (b/c)'.
            if (!ptr1 && is_scalar(arg2) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if ((op==mp_mul || op==mp_div) && pop[1]==arg2) {
                p2 = code.size() - 1;
                ptr2 = pop.data();
              }
            }
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (!arg2) _cimg_mp_same(arg1);
            if (is_vector(arg1) || is_vector(arg2)) {
              if (!arg1) _cimg_mp_vector1(minus,arg2);
              _cimg_mp_vector2(sub,arg1,arg2);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2)) _cimg_mp_const_scalar(mem[arg1] - mem[arg2]);
            if (!arg1) _cimg_mp_scalar1(minus,arg2);
            if (p1<code.size() && code[p1].data()==ptr1 && ptr1[1]==(ulongT)arg1) {
              arg3 = (unsigned int)ptr1[2]; arg4 = (unsigned int)ptr1[3];
              op = (mp_func)*ptr1;
              code.remove(p1);
              if (op==mp_sub) { // Particular case '(a - b) - c'
                if (is_const_scalar(arg2)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(sub,const_scalar(mem[arg3] - mem[arg2]),arg4);
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(sub,arg3,const_scalar(mem[arg2] + mem[arg4]));
                }
                _cimg_mp_scalar3(sub_sub,arg3,arg4,arg2);
              }
              else if (op==mp_mul) _cimg_mp_scalar3(mul_sub,arg3,arg4,arg2); // Particular case '(a*b) - c'
              _cimg_mp_scalar3(div_sub,arg3,arg4,arg2); // Particular case '(a/b) - c'
            }
            if (p2<code.size() && code[p2].data()==ptr2 && ptr2[1]==(ulongT)arg2) {
              arg3 = (unsigned int)ptr2[2]; arg4 = (unsigned int)ptr2[3];
              op = (mp_func)*ptr2;
              code.remove(p2);
              if (op==mp_mul) _cimg_mp_scalar3(sub_mul,arg1,arg3,arg4); // Particular case 'a - (b*c)'
              _cimg_mp_scalar3(sub_div,arg1,arg3,arg4); // Particular case 'a - (b/c)'
            }
            if (arg2==1) _cimg_mp_scalar1(decrement,arg1);
            _cimg_mp_scalar2(sub,arg1,arg2);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='*' && *ns=='*' && level[s - expr._data]==clevel) { // Complex multiplication ('**')
            _cimg_mp_op("Operator '**'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,3,2);
            _cimg_mp_check_type(arg2,2,3,2);
            if (arg2==1) _cimg_mp_same(arg1);
            if (arg1==1) _cimg_mp_same(arg2);
            if (is_vector(arg1) && is_vector(arg2)) {
              pos = vector(2);
              CImg<ulongT>::vector((ulongT)mp_complex_mul,pos,arg1,arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            if ((is_vector(arg1) && is_scalar(arg2)) ||
                (is_scalar(arg1) && is_vector(arg2))) _cimg_mp_vector2(mul,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]*mem[arg2]);
            if (!arg1 || !arg2) _cimg_mp_return(0);
            _cimg_mp_scalar2(mul,arg1,arg2);
          }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='/' && *ns=='/' && level[s - expr._data]==clevel) { // Complex division ('//')
            _cimg_mp_op("Operator '//'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,3,2);
            _cimg_mp_check_type(arg2,2,3,2);
            if (arg2==1) _cimg_mp_same(arg1);
            if (is_vector(arg1) && is_vector(arg2)) {
              pos = vector(2);
              CImg<ulongT>::vector((ulongT)mp_complex_div_vv,pos,arg1,arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            if (is_vector(arg1) && is_scalar(arg2)) _cimg_mp_vector2(div,arg1,arg2);
            if (is_scalar(arg1) && is_vector(arg2)) {
              pos = vector(2);
              CImg<ulongT>::vector((ulongT)mp_complex_div_sv,pos,arg1,arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]/mem[arg2]);
            if (!arg1) _cimg_mp_return(0);
            _cimg_mp_scalar2(div,arg1,arg2);
          }

        for (s = se2; s>ss; --s) if (*s=='*' && level[s - expr._data]==clevel) { // Multiplication ('*')
            _cimg_mp_op("Operator '*'");
            p1 = p2 = ~0U;
            const ulongT *ptr1 = 0, *ptr2 = 0;
            p3 = code.size();
            arg1 = compile(ss,s,depth1,0,block_flags);

            // Spot cases '(a*b)*c' and '(a/b)*c'.
            if (is_scalar(arg1) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if ((op==mp_mul || op==mp_div) && pop[1]==arg1) {
                p1 = code.size() - 1;
                ptr1 = pop.data();
              }
            }
            arg2 = compile(s + 1,se,depth1,0,block_flags);

            // Spot case 'a*(b/c)'.
            if (!ptr1 && is_scalar(arg2) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if (op==mp_div && pop[1]==arg2) {
                p2 = code.size() - 1;
                ptr2 = pop.data();
              }
            }

            p3 = size(arg2);
            if (p3>0 && (ulongT)size(arg1)==(ulongT)p3*p3) { // Particular case of matrix multiplication
              pos = vector(p3);
              CImg<ulongT>::vector((ulongT)mp_matrix_mul,pos,arg1,arg2,p3,p3,1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (arg2==1) _cimg_mp_same(arg1);
            if (arg1==1) _cimg_mp_same(arg2);
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(mul,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2)) _cimg_mp_const_scalar(mem[arg1]*mem[arg2]);
            if (!arg1 || !arg2) _cimg_mp_return(0);
            if (p1<code.size() && code[p1].data()==ptr1 && ptr1[1]==(ulongT)arg1) {
              arg3 = (unsigned int)ptr1[2]; arg4 = (unsigned int)ptr1[3];
              op = (mp_func)*ptr1;
              code.remove(p1);
              if (op==mp_mul) { // Particular case '(a*b)*c'
                if (is_const_scalar(arg2)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(mul,arg4,const_scalar(mem[arg2]*mem[arg3]));
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(mul,arg3,const_scalar(mem[arg2]*mem[arg4]));
                }
                _cimg_mp_scalar3(mul_mul,arg3,arg4,arg2);
              } else { // Particular case '(a/b)*c'
                if (is_const_scalar(arg2)) {
                  if (is_const_scalar(arg3)) _cimg_mp_scalar2(div,const_scalar(mem[arg3]*mem[arg2]),arg4);
                  if (is_const_scalar(arg4)) _cimg_mp_scalar2(mul,arg3,const_scalar(mem[arg2]/mem[arg4]));
                }
                _cimg_mp_scalar3(mul_div,arg2,arg3,arg4);
              }
            }
            if (p2<code.size() && code[p2].data()==ptr2 && *ptr2==(ulongT)mp_div &&
                ptr2[1]==(ulongT)arg2) { // Particular case 'a*(b/c)'
              arg3 = (unsigned int)ptr2[2]; arg4 = (unsigned int)ptr2[3];
              code.remove(p2);
              if (is_const_scalar(arg1)) {
                if (is_const_scalar(arg3)) _cimg_mp_scalar2(div,const_scalar(mem[arg1]*mem[arg3]),arg4);
                if (is_const_scalar(arg4)) _cimg_mp_scalar2(mul,arg3,const_scalar(mem[arg1]/mem[arg4]));
              }
              _cimg_mp_scalar3(mul_div,arg1,arg3,arg4);
            }
            _cimg_mp_scalar2(mul,arg1,arg2);
          }

        for (s = se2; s>ss; --s) if (*s=='/' && level[s - expr._data]==clevel) { // Division ('/')
            _cimg_mp_op("Operator '/'");
            p1 = ~0U;
            const ulongT *ptr1 = 0;
            p3 = code.size();
            arg1 = compile(ss,s,depth1,0,block_flags);

            // Spot case 'a/b/c'.
            if (is_scalar(arg1) && code.size()>p3) {
              CImg<ulongT>& pop = code.back();
              op = (mp_func)*pop;
              if (op==mp_div && pop[1]==arg1) {
                p1 = code.size() - 1;
                ptr1 = pop.data();
              }
            }
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (arg2==1) _cimg_mp_same(arg1);
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(div,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(mem[arg1]/mem[arg2]);
            if (!arg1) _cimg_mp_return(0);
            if (p1<code.size() && code[p1].data()==ptr1 && *ptr1==(ulongT)mp_div &&
                ptr1[1]==(ulongT)arg1) { // Particular case '(a/b)/c'
              arg3 = (unsigned int)ptr1[2]; arg4 = (unsigned int)ptr1[3];
              code.remove(p1);
              if (is_const_scalar(arg2)) {
                if (is_const_scalar(arg3)) _cimg_mp_scalar2(div,const_scalar(mem[arg3]/mem[arg2]),arg4);
                if (is_const_scalar(arg4)) _cimg_mp_scalar2(div,arg3,const_scalar(mem[arg2]*mem[arg4]));
              }
              _cimg_mp_scalar3(div_div,arg3,arg4,arg2);
            }
            _cimg_mp_scalar2(div,arg1,arg2);
          }

        for (s = se2, ns = se1, ps = se3; s>ss; --s, --ns, --ps)
          if (*s=='%' && *ns!='^' && *ps!='$' && level[s - expr._data]==clevel) { // Modulo ('%')
            _cimg_mp_op("Operator '%'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(modulo,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(cimg::mod(mem[arg1],mem[arg2]));
            _cimg_mp_scalar2(modulo,arg1,arg2);
          }

        if (se1>ss) {
          if (*ss=='+' && (*ss1!='+' || (ss2<se && *ss2>='0' && *ss2<='9'))) { // Unary plus ('+')
            _cimg_mp_op("Operator '+'");
            _cimg_mp_return(compile(ss1,se,depth1,0,block_flags));
          }

          if (*ss=='-' && (*ss1!='-' || (ss2<se && *ss2>='0' && *ss2<='9'))) { // Unary minus ('-')
            _cimg_mp_op("Operator '-'");
            arg1 = compile(ss1,se,depth1,0,block_flags);
            if (is_vector(arg1)) _cimg_mp_vector1(minus,arg1);
            if (is_const_scalar(arg1)) _cimg_mp_const_scalar(-mem[arg1]);
            _cimg_mp_scalar1(minus,arg1);
          }

          if (*ss=='!') { // Logical not ('!')
            _cimg_mp_op("Operator '!'");
            if (*ss1=='!') { // '!!expr' optimized as 'bool(expr)'
              arg1 = compile(ss2,se,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(bool,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar((bool)mem[arg1]);
              _cimg_mp_scalar1(bool,arg1);
            }
            arg1 = compile(ss1,se,depth1,0,block_flags);
            if (is_vector(arg1)) _cimg_mp_vector1(logical_not,arg1);
            if (is_const_scalar(arg1)) _cimg_mp_const_scalar(!mem[arg1]);
            _cimg_mp_scalar1(logical_not,arg1);
          }

          if (*ss=='~') { // Bitwise not ('~')
            _cimg_mp_op("Operator '~'");
            arg1 = compile(ss1,se,depth1,0,block_flags);
            if (is_vector(arg1)) _cimg_mp_vector1(bitwise_not,arg1);
            if (is_const_scalar(arg1)) _cimg_mp_const_scalar(~(unsigned int)(int64T)mem[arg1]);
            _cimg_mp_scalar1(bitwise_not,arg1);
          }
        }

        for (s = se3, ns = se2; s>ss; --s, --ns)
          if (*s=='^' && *ns=='^' && level[s - expr._data]==clevel) { // Complex power ('^^')
            _cimg_mp_op("Operator '^^'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 2,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg1,1,3,2);
            _cimg_mp_check_type(arg2,2,3,2);
            if (arg2==1) _cimg_mp_same(arg1);
            pos = vector(2);
            if (!arg2) CImg<ulongT>::vector((ulongT)mp_complex_one,pos).move_to(code);
            else if (arg2==2) {
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_sqr,pos,2,arg1).move_to(code);
            } else {
              if (is_vector(arg1) && is_vector(arg2))
                CImg<ulongT>::vector((ulongT)mp_complex_pow_vv,pos,arg1,arg2).move_to(code);
              else if (is_vector(arg1) && is_scalar(arg2))
                CImg<ulongT>::vector((ulongT)mp_complex_pow_vs,pos,arg1,arg2).move_to(code);
              else if (is_scalar(arg1) && is_vector(arg2))
                CImg<ulongT>::vector((ulongT)mp_complex_pow_sv,pos,arg1,arg2).move_to(code);
              else
                CImg<ulongT>::vector((ulongT)mp_complex_pow_ss,pos,arg1,arg2).move_to(code);
            }
            return_comp = true;
            _cimg_mp_return(pos);
          }

        for (s = se2; s>ss; --s)
          if (*s=='^' && level[s - expr._data]==clevel) { // Power ('^')
            _cimg_mp_op("Operator '^'");
            arg1 = compile(ss,s,depth1,0,block_flags);
            arg2 = compile(s + 1,se,depth1,0,block_flags);
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            if (arg2==1) _cimg_mp_same(arg1);
            if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(pow,arg1,arg2);
            if (is_const_scalar(arg1) && is_const_scalar(arg2))
              _cimg_mp_const_scalar(std::pow(mem[arg1],mem[arg2]));
            switch (arg2) {
            case 0 : _cimg_mp_return(1);
            case 2 : _cimg_mp_scalar1(sqr,arg1);
            case 3 : _cimg_mp_scalar1(pow3,arg1);
            case 4 : _cimg_mp_scalar1(pow4,arg1);
            default :
              if (is_const_scalar(arg2)) {
                if (mem[arg2]==0.5) { _cimg_mp_scalar1(sqrt,arg1); }
                else if (mem[arg2]==0.25) { _cimg_mp_scalar1(pow0_25,arg1); }
              }
              _cimg_mp_scalar2(pow,arg1,arg2);
            }
          }

      cimg_skip_iterative_operator_parsing :

        // Percentage computation.
        if (*se1=='%' && se1>ss && *se2!='$') {
          arg1 = compile(ss,se1,depth1,0,block_flags);
          arg2 = is_const_scalar(arg1)?0:const_scalar(100);
          if (is_vector(arg1)) _cimg_mp_vector2(div,arg1,arg2);
          if (is_const_scalar(arg1)) _cimg_mp_const_scalar(mem[arg1]/100);
          _cimg_mp_scalar2(div,arg1,arg2);
        }

        // Degree to radian postfix operator ('°' in UTF-8).
        if (se2>ss && (unsigned char)*se2==0xC2 && (unsigned char)*se1==0xB0) {
          arg1 = compile(ss,se2,depth1,0,block_flags);
          if (is_vector(arg1)) _cimg_mp_vector1(deg2rad,arg1);
          if (is_const_scalar(arg1)) _cimg_mp_const_scalar(mem[arg1]*cimg::PI/180);
          _cimg_mp_scalar1(deg2rad,arg1);
        }

        // Pre/post-decrement and increment.
        is_sth = ss1<se1 && (*ss=='+' || *ss=='-') && *ss1==*ss; // is pre-?
        if (is_sth || (se2>ss && (*se1=='+' || *se1=='-') && *se2==*se1)) {
          if ((is_sth && *ss=='+') || (!is_sth && *se1=='+')) {
            _cimg_mp_op("Operator '++'");
            op = mp_self_increment;
          } else {
            _cimg_mp_op("Operator '--'");
            op = mp_self_decrement;
          }
          ref.assign(7);
          arg1 = is_sth?compile(ss2,se,depth1,ref,block_flags):
            compile(ss,se2,depth1,ref,block_flags); // Variable slot

          pos = is_sth?arg1:copy(arg1); // Determine return index, depending on pre/post action

          if (*ref==1) { // Vector value (scalar): V[k]++
            arg3 = ref[1]; // Vector slot
            arg4 = ref[2]; // Index
            if (is_sth && p_ref) std::memcpy(p_ref,ref,ref._width*sizeof(unsigned int));
            CImg<ulongT>::vector((ulongT)op,arg1,1).move_to(code);
            CImg<ulongT>::vector((ulongT)mp_vector_set_off,arg1,arg3,(ulongT)size(arg3),arg4).
              move_to(code);
            _cimg_mp_return(pos);
          }

          if (*ref==2) { // Image value (scalar): i/j[_#ind,off]++
            if (!is_inside_critical) is_parallelizable = false;
            p1 = ref[1]; // Index
            is_relative = (bool)ref[2];
            arg3 = ref[3]; // Offset
            if (is_sth && p_ref) std::memcpy(p_ref,ref,ref._width*sizeof(unsigned int));
            CImg<ulongT>::vector((ulongT)op,arg1).move_to(code);
            if ((p1==~0U && imgout) || (p1!=~0U && imglist))
              CImg<ulongT>::vector((ulongT)mp_set_ijoff,arg1,(ulongT)is_relative,
                                   p1,arg3).move_to(code);
            _cimg_mp_return(pos);
          }

          if (*ref==3) { // Image value (scalar): i/j(_#ind,_x,_y,_z,_c)++
            if (!is_inside_critical) is_parallelizable = false;
            p1 = ref[1]; // Index
            is_relative = (bool)ref[2];
            arg3 = ref[3]; // X
            arg4 = ref[4]; // Y
            arg5 = ref[5]; // Z
            arg6 = ref[6]; // C
            if (is_sth && p_ref) std::memcpy(p_ref,ref,ref._width*sizeof(unsigned int));
            CImg<ulongT>::vector((ulongT)op,arg1).move_to(code);
            if ((p1==~0U && imgout) || (p1!=~0U && imglist))
              CImg<ulongT>::vector((ulongT)mp_set_ijxyzc,arg1,(ulongT)is_relative,
                                   p1,arg3,arg4,arg5,arg6).move_to(code);
            _cimg_mp_return(pos);
          }

          if (*ref==4) { // Image value (vector): I/J[_#ind,off]++
            if (!is_inside_critical) is_parallelizable = false;
            p1 = ref[1]; // Index
            is_relative = (bool)ref[2];
            arg3 = ref[3]; // Offset
            if (is_sth && p_ref) std::memcpy(p_ref,ref,ref._width*sizeof(unsigned int));
            _cimg_mp_self_vector1(op==mp_self_increment?mp_self_vector_increment:mp_self_vector_decrement,arg1);
            if ((p1==~0U && imgout) || (p1!=~0U && imglist))
              CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg1,(ulongT)is_relative,
                                   p1,arg3,size(arg1)).move_to(code);
            _cimg_mp_return(pos);
          }

          if (*ref==5) { // Image value (vector): I/J(_#ind,_x,_y,_z,_c)++
            if (!is_inside_critical) is_parallelizable = false;
            p1 = ref[1]; // Index
            is_relative = (bool)ref[2];
            arg3 = ref[3]; // X
            arg4 = ref[4]; // Y
            arg5 = ref[5]; // Z
            if (is_sth && p_ref) std::memcpy(p_ref,ref,ref._width*sizeof(unsigned int));
            _cimg_mp_self_vector1(op==mp_self_increment?mp_self_vector_increment:mp_self_vector_decrement,arg1);
            if ((p1==~0U && imgout) || (p1!=~0U && imglist))
              CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg1,(ulongT)is_relative,
                                   p1,arg3,arg4,arg5,size(arg1)).move_to(code);
            _cimg_mp_return(pos);
          }

          if (is_vector(arg1)) { // Vector variable: V++
            _cimg_mp_self_vector1(op==mp_self_increment?mp_self_vector_increment:mp_self_vector_decrement,arg1);
            _cimg_mp_return(pos);
          }

          if (is_reserved(arg1)) { // Scalar variable: s++
            CImg<ulongT>::vector((ulongT)op,arg1).move_to(code);
            _cimg_mp_return(pos);
          }

          if (is_sth) variable_name.assign(ss2,(unsigned int)(se - ss1));
          else variable_name.assign(ss,(unsigned int)(se1 - ss));
          variable_name.back() = 0;
          cimg::strpare(variable_name,false,true);
          cimg::strellipsize(variable_name,64);
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s: Invalid %slvalue '%s', "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,
                                      is_const_scalar(arg1)?"const ":"",
                                      variable_name._data,s0);
        }

        // Array-like access to vectors and image values 'i/j/I/J[_#ind,offset,_boundary]' and 'vector[offset]'.
        if (*se1==']') {
          _cimg_mp_op("Value accessor '[]'");

          // Find opening bracket for the offset.
          s0 = se1; while (s0>ss && (*s0!='[' || level[s0 - expr._data]!=clevel)) --s0;
          if (s0>ss) { s1 = s0; do { --s1; } while (cimg::is_blank(*s1)); cimg::swap(*s0,*++s1); }
          is_sth=s0>ss && *(s0-1)==']'; // Particular case s.a. '..[..][..]' ?
          is_relative = *ss=='j' || *ss=='J';

          if (!is_sth && (*ss=='I' || *ss=='J') && *ss1=='[' &&
              (reserved_label[(int)*ss]==~0U ||
               !is_vector(reserved_label[(int)*ss]))) { // Image value as a vector
            if (*ss2=='#') { // Index specified
              s0 = ss3; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              p1 = compile(ss3,s0++,depth1,0,block_flags);
              _cimg_mp_check_const_index(p1);
              _cimg_mp_check_notnan_index(p1,ss3);
              _cimg_mp_check_list();
            } else { p1 = ~0U; s0 = ss2; }
            s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
            p2 = 1 + (p1!=~0U);
            arg1 = compile(s0,s1,depth1,0,block_flags); // Offset
            _cimg_mp_check_type(arg1,p2,1,0);
            arg2 = ~0U;
            if (s1<se1) {
              arg2 = compile(++s1,se1,depth1,0,block_flags); // Boundary
              _cimg_mp_check_type(arg2,p2 + 1,1,0);
            }
            if (p_ref && arg2==~0U) {
              *p_ref = 4;
              p_ref[1] = p1;
              p_ref[2] = (unsigned int)is_relative;
              p_ref[3] = arg1;
              if (is_comp_scalar(arg1)) memtype[arg1] = -1;
            }
            p2 = ~0U; // 'p2' must be the dimension of the vector-valued operand if any
            if (p1==~0U) p2 = imgin._spectrum;
            else {
              p3 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
              p2 = imglist[p3]._spectrum;
            }
            if (!p2) _cimg_mp_return(0);
            pos = vector(p2);
            if (p1==~0U) need_input_copy = true;
            CImg<ulongT>::vector((ulongT)mp_IJoff,pos,(ulongT)is_relative,p1,
                                 arg1,arg2==~0U?_cimg_mp_boundary:arg2,p2).move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          }

          if (!is_sth && (*ss=='i' || *ss=='j') && *ss1=='[' &&
              (reserved_label[(int)*ss]==~0U ||
               !is_vector(reserved_label[(int)*ss]))) { // Image value as a scalar
            if (*ss2=='#') { // Index specified
              s0 = ss3; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              p1 = compile(ss3,s0++,depth1,0,block_flags);
              _cimg_mp_check_notnan_index(p1,ss3);
            } else { p1 = ~0U; s0 = ss2; }
            s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
            arg1 = compile(s0,s1,depth1,0,block_flags); // Offset
            arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U; // Boundary
            if (p_ref && arg2==~0U) {
              *p_ref = 2;
              p_ref[1] = p1;
              p_ref[2] = (unsigned int)is_relative;
              p_ref[3] = arg1;
              if (p1!=~0U && is_comp_scalar(p1)) memtype[p1] = -1; // Prevent from being used in further optimization
              if (is_comp_scalar(arg1)) memtype[arg1] = -1;
            }
            if (p1==~0U) { if (!imgin) _cimg_mp_return(0); need_input_copy = true; }
            else if (!imglist) _cimg_mp_return(0);
            pos = scalar4(mp_ijoff,(unsigned int)is_relative,p1,arg1,arg2==~0U?_cimg_mp_boundary:arg2);
            memtype[pos] = -1; // Prevent from being used in further optimization
            _cimg_mp_return(pos);
          }

          s0 = se1; while (s0>ss && (*s0!='[' || level[s0 - expr._data]!=clevel)) --s0;
          if (s0>ss) { // Vector element
            arg1 = compile(ss,s0,depth1,0,block_flags);
            if (is_scalar(arg1)) {
              variable_name.assign(ss,(unsigned int)(s0 - ss + 1)).back() = 0;
              cimg::strellipsize(variable_name,64);
              _cimg_mp_strerr;
              throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                          "CImg<%s>::%s: %s: Array brackets used on non-vector variable '%s', "
                                          "in expression '%s'.",
                                          pixel_type(),_cimg_mp_calling_function,s_op,
                                          variable_name._data,s0);
            }
            s1 = s0 + 1; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;

            if (s1<se1) { // Two or three arguments -> sub-vector extraction
              p1 = size(arg1);
              arg2 = compile(++s0,s1,depth1,0,block_flags); // Starting index
              s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              arg3 = compile(s1,s0,depth1,0,block_flags); // Length
              arg4 = s0<se1?compile(++s0,se1,depth1,0,block_flags):1; // Step
              _cimg_mp_check_const_scalar(arg3,2,3);
              arg3 = (unsigned int)mem[arg3];
              pos = vector(arg3);
              CImg<ulongT>::vector((ulongT)mp_vector_crop,pos,arg1,p1,arg2,arg3,arg4).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            // One argument -> vector value reference.
            arg2 = compile(++s0,se1,depth1,0,block_flags);
            if (is_const_scalar(arg2)) { // Constant index
              nb = (int)mem[arg2];
              if (nb>=0 && nb<(int)size(arg1)) _cimg_mp_return(arg1 + 1 + nb);
              variable_name.assign(ss,(unsigned int)(s0 - ss)).back() = 0;
              cimg::strellipsize(variable_name,64);
              _cimg_mp_strerr;
              throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                          "CImg<%s>::%s: Out-of-bounds reference '%s[%d]' "
                                          "(vector '%s' has dimension %u), "
                                          "in expression '%s'.",
                                          pixel_type(),_cimg_mp_calling_function,
                                          variable_name._data,nb,
                                          variable_name._data,size(arg1),s0);
            }
            if (p_ref) {
              *p_ref = 1;
              p_ref[1] = arg1;
              p_ref[2] = arg2;
              if (is_comp_scalar(arg2)) memtype[arg2] = -1; // Prevent from being used in further optimization
            }
            pos = scalar3(mp_vector_off,arg1,size(arg1),arg2);
            memtype[pos] = -1; // Prevent from being used in further optimization
            _cimg_mp_return(pos);
          }
        }

        // Look for a function call, an access to image value, or a parenthesis.
        if (*se1==')') {
          if (*ss=='(') _cimg_mp_return(compile(ss1,se1,depth1,p_ref,block_flags)); // Simple parentheses
          _cimg_mp_op("Value accessor '()'");
          is_relative = *ss=='j' || *ss=='J';
          s0 = s1 = std::strchr(ss,'('); if (s0) { do { --s1; } while (cimg::is_blank(*s1)); cimg::swap(*s0,*++s1); }

          // I/J(_#ind,_x,_y,_z,_interpolation,_boundary_conditions).
          if ((*ss=='I' || *ss=='J') && *ss1=='(') { // Image value as scalar
            if (*ss2=='#') { // Index specified
              s0 = ss3; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              p1 = compile(ss3,s0++,depth1,0,block_flags);
              _cimg_mp_check_const_index(p1);
              _cimg_mp_check_notnan_index(p1,ss3);
              _cimg_mp_check_list();
            } else { p1 = ~0U; s0 = ss2; }
            arg1 = is_relative?0U:(unsigned int)_cimg_mp_slot_x;
            arg2 = is_relative?0U:(unsigned int)_cimg_mp_slot_y;
            arg3 = is_relative?0U:(unsigned int)_cimg_mp_slot_z;
            arg4 = arg5 = ~0U;
            if (s0<se1) {
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              if (is_vector(arg1)) { // Coordinates specified as a vector
                p2 = size(arg1);
                ++arg1;
                if (p2>1) {
                  arg2 = arg1 + 1;
                  if (p2>2) arg3 = arg2 + 1;
                }
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg4 = compile(s1,s2,depth1,0,block_flags);
                  arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):~0U;
                }
              } else if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                if (s2<se1) {
                  s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                  arg3 = compile(s2,s3,depth1,0,block_flags);
                  if (s3<se1) {
                    s2 = ++s3; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg4 = compile(s3,s2,depth1,0,block_flags);
                    arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):~0U;
                  }
                }
              }
            }
            if (p_ref && arg4==~0U && arg5==~0U) {
              *p_ref = 5;
              p_ref[1] = p1;
              p_ref[2] = (unsigned int)is_relative;
              p_ref[3] = arg1;
              p_ref[4] = arg2;
              p_ref[5] = arg3;
              if (p1!=~0U && is_comp_scalar(p1)) memtype[p1] = -1; // Prevent from being used in further optimization
              if (is_comp_scalar(arg1)) memtype[arg1] = -1;
              if (is_comp_scalar(arg2)) memtype[arg2] = -1;
              if (is_comp_scalar(arg3)) memtype[arg3] = -1;
            }
            p2 = ~0U; // 'p2' must be the dimension of the vector-valued operand if any
            if (p1==~0U) p2 = imgin._spectrum;
            else if (is_const_scalar(p1)) {
              p3 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
              p2 = imglist[p3]._spectrum;
            }
            if (!p2) _cimg_mp_return(0);
            pos = vector(p2);
            const bool
              is_intz = is_const_integer(arg3) || (arg3>=_cimg_mp_slot_x && arg3<=_cimg_mp_slot_c), // optimized for 2D?
              is_inty = is_intz && // optimized for 1D?
              (is_const_integer(arg2) || (arg2>=_cimg_mp_slot_x && arg2<=_cimg_mp_slot_c));
            if (p1==~0U) need_input_copy = true;
            CImg<ulongT>::vector((ulongT)(is_inty?mp_IJxyz1:is_intz?mp_IJxyz2:mp_IJxyz3),
                                 pos,(ulongT)is_relative,p1,arg1,arg2,arg3,
                                 arg4==~0U?_cimg_mp_interpolation:arg4,
                                 arg5==~0U?_cimg_mp_boundary:arg5,p2).move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          }

          // i/j(_#ind,_x,_y,_z,_c,_interpolation,_boundary_conditions).
          if ((*ss=='i' || *ss=='j') && *ss1=='(') { // Image value as scalar
            if (*ss2=='#') { // Index specified
              s0 = ss3; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              p1 = compile(ss3,s0++,depth1,0,block_flags);
              _cimg_mp_check_notnan_index(p1,ss3);
            } else { p1 = ~0U; s0 = ss2; }
            arg1 = is_relative?0U:(unsigned int)_cimg_mp_slot_x;
            arg2 = is_relative?0U:(unsigned int)_cimg_mp_slot_y;
            arg3 = is_relative?0U:(unsigned int)_cimg_mp_slot_z;
            arg4 = is_relative?0U:(unsigned int)_cimg_mp_slot_c;
            arg5 = arg6 = ~0U;
            if (s0<se1) {
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              if (is_vector(arg1)) { // Coordinates specified as a vector
                p2 = size(arg1);
                ++arg1;
                if (p2>1) {
                  arg2 = arg1 + 1;
                  if (p2>2) {
                    arg3 = arg2 + 1;
                    if (p2>3) arg4 = arg3 + 1;
                  }
                }
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg5 = compile(s1,s2,depth1,0,block_flags);
                  arg6 = s2<se1?compile(++s2,se1,depth1,0,block_flags):~0U;
                }
              } else if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                if (s2<se1) {
                  s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                  arg3 = compile(s2,s3,depth1,0,block_flags);
                  if (s3<se1) {
                    s2 = ++s3; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg4 = compile(s3,s2,depth1,0,block_flags);
                    if (s2<se1) {
                      s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                      arg5 = compile(s2,s3,depth1,0,block_flags);
                      arg6 = s3<se1?compile(++s3,se1,depth1,0,block_flags):~0U;
                    }
                  }
                }
              }
            }
            if (p_ref && arg5==~0U && arg6==~0U) {
              *p_ref = 3;
              p_ref[1] = p1;
              p_ref[2] = (unsigned int)is_relative;
              p_ref[3] = arg1;
              p_ref[4] = arg2;
              p_ref[5] = arg3;
              p_ref[6] = arg4;
              if (p1!=~0U && is_comp_scalar(p1)) memtype[p1] = -1; // Prevent from being used in further optimization
              if (is_comp_scalar(arg1)) memtype[arg1] = -1;
              if (is_comp_scalar(arg2)) memtype[arg2] = -1;
              if (is_comp_scalar(arg3)) memtype[arg3] = -1;
              if (is_comp_scalar(arg4)) memtype[arg4] = -1;
            }

            const bool
              is_intz = is_const_integer(arg3) || (arg3>=_cimg_mp_slot_x && arg3<=_cimg_mp_slot_c), // optimized for 2D?
              is_inty = is_intz && // optimized for 1D?
              (is_const_integer(arg2) || (arg2>=_cimg_mp_slot_x && arg2<=_cimg_mp_slot_c));
            if (p1==~0U) { if (!imgin) _cimg_mp_return(0); need_input_copy = true; }
            else if (!imglist) _cimg_mp_return(0);
            pos = scalar8(is_inty?mp_ijxyzc1:is_intz?mp_ijxyzc2:mp_ijxyzc3,
                          (unsigned int)is_relative,p1,arg1,arg2,arg3,arg4,
                          arg5==~0U?_cimg_mp_interpolation:arg5,
                          arg6==~0U?_cimg_mp_boundary:arg6);
            memtype[pos] = -1; // Prevent from being used in further optimization
            _cimg_mp_return(pos);
          }

          // Mathematical functions.
          switch (*ss) {
          case 'a' :

#ifdef cimg_mp_func_abort
            if (!std::strncmp(ss,"abort(",6)) { // Abort
              _cimg_mp_op("Function 'abort()'");
              if (pexpr[se2 - expr._data]=='(') { // no arguments?
                CImg<ulongT>::vector((ulongT)mp_abort,_cimg_mp_slot_nan).move_to(code);
                _cimg_mp_return_nan();
              }
            }
#endif

            if (!std::strncmp(ss,"abs(",4)) { // Absolute value
              _cimg_mp_op("Function 'abs()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (code) { // Spot 'abs(maxabs())' and 'abs(minabs())' cases
                CImg<ulongT> &pop = code.back();
                op = (mp_func)*pop;
                if (op==mp_maxabs) { pop[0] = (ulongT)mp_absmaxabs; _cimg_mp_return(pop[1]); }
                else if (op==mp_minabs) { pop[0] = (ulongT)mp_absminabs; _cimg_mp_return(pop[1]); }
              }
              if (is_vector(arg1)) _cimg_mp_vector1(abs,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::abs(mem[arg1]));
              _cimg_mp_scalar1(abs,arg1);
            }

            if (!std::strncmp(ss,"abscut(",7)) { // Cut of absolute value
              _cimg_mp_op("Function 'abscut()'");
              s1 = ss7; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss7,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):0;
              } else { arg3 = const_scalar(cimg::type<double>::inf()); arg4 = 0; }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              _cimg_mp_check_type(arg4,3,1,0);
              if (is_vector(arg1)) {
                p1 = size(arg1);
                pos = vector(p1);
                CImg<ulongT>::vector((ulongT)mp_vector_abscut,pos,p1,arg1,arg2,arg3,arg4).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }
              if (is_const_scalar(arg1) && is_const_scalar(arg2) && is_const_scalar(arg3) && is_const_scalar(arg4)) {
                val = mem[arg1];
                val1 = mem[arg2];
                val2 = mem[arg3];
                val3 = mem[arg4];
                _cimg_mp_const_scalar(cimg::abscut(val,val1,val2,val3));
              }
              _cimg_mp_scalar4(abscut,arg1,arg2,arg3,arg4);
            }

            if (!std::strncmp(ss,"addr(",5)) { // Pointer address
              _cimg_mp_op("Function 'addr()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_const_scalar((double)arg1);
            }

            if (!std::strncmp(ss,"acos(",5)) { // Arccos
              _cimg_mp_op("Function 'acos()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(acos,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::acos(mem[arg1]));
              _cimg_mp_scalar1(acos,arg1);
            }

            if (!std::strncmp(ss,"acosh(",6)) { // Hyperbolic arccosine
              _cimg_mp_op("Function 'acosh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(acosh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::acosh(mem[arg1]));
              _cimg_mp_scalar1(acosh,arg1);
            }

            if (!std::strncmp(ss,"arg0(",5) ||
                !std::strncmp(ss,"arg1(",5)) { // Nth argument
              _cimg_mp_op(*ss3=='0'?"Function 'arg0()'":"Function 'arg1()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,1,0);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              p2 = size(arg2);
              p3 = 3;
              CImg<ulongT>::vector((ulongT)(*ss3=='0'?mp_arg0:mp_arg1),0,0,p2,arg1,arg2).move_to(l_opcode);
              for (s = ++s2; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg3 = compile(s,ns,depth1,0,block_flags);
                _cimg_mp_check_type(arg3,p3,p2?2:1,p2);
                CImg<ulongT>::vector(arg3).move_to(l_opcode);
                ++p3;
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              opcode[2] = opcode._height - 4;
              if (is_const_scalar(arg1)) {
                p3-=1; // Number of args
                if (*ss3=='0') arg1 = (unsigned int)(mem[arg1]<0?mem[arg1] + p3:mem[arg1] + 1);
                else arg1 = (unsigned int)(mem[arg1]<0?mem[arg1] + p3:mem[arg1]);
                if (arg1<p3) _cimg_mp_return(opcode[4 + arg1]);
                if (p2) {
                  pos = vector(p2);
                  std::memset(&mem[pos] + 1,0,p2*sizeof(double));
                  return_comp = true;
                  _cimg_mp_return(pos);
                } else _cimg_mp_return(0);
              }
              pos = opcode[1] = p2?vector(p2):scalar();
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"asin(",5)) { // Arcsin
              _cimg_mp_op("Function 'asin()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(asin,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::asin(mem[arg1]));
              _cimg_mp_scalar1(asin,arg1);
            }

            if (!std::strncmp(ss,"asinh(",6)) { // Hyperbolic arcsine
              _cimg_mp_op("Function 'asinh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(asinh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::asinh(mem[arg1]));
              _cimg_mp_scalar1(asinh,arg1);
            }

            if (!std::strncmp(ss,"atan(",5)) { // Arctan
              _cimg_mp_op("Function 'atan()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(atan,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::atan(mem[arg1]));
              _cimg_mp_scalar1(atan,arg1);
            }

            if (!std::strncmp(ss,"atan2(",6)) { // Arctan2
              _cimg_mp_op("Function 'atan2()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg2,2,3,size(arg1));
              if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(atan2,arg1,arg2);
              if (is_const_scalar(arg1) && is_const_scalar(arg2))
                _cimg_mp_const_scalar(std::atan2(mem[arg1],mem[arg2]));
              _cimg_mp_scalar2(atan2,arg1,arg2);
            }

            if (!std::strncmp(ss,"atanh(",6)) { // Hyperbolic arctangent
              _cimg_mp_op("Function 'atanh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(atanh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::atanh(mem[arg1]));
              _cimg_mp_scalar1(atanh,arg1);
            }
            break;

          case 'b' :
            if (!std::strncmp(ss,"begin(",6)) { // Begin
              _cimg_mp_op("Function 'begin()'");
              s1 = ss6; while (s1<se1 && cimg::is_blank(*s1)) ++s1;
              if (s1!=se1) {
                if (!is_inside_begin) code.swap(code_begin);
                arg1 = compile(s1,se1,depth1,p_ref,2);
                if (!is_inside_begin) code.swap(code_begin);
                _cimg_mp_return(arg1);
              } else _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"begin_t(",8)) { // Begin thread
              _cimg_mp_op("Function 'begin_t()'");
              s1 = ss8; while (s1<se1 && cimg::is_blank(*s1)) ++s1;
              if (s1!=se1) {
                if (!is_inside_begin_t) code.swap(code_begin_t);
                arg1 = compile(s1,se1,depth1,p_ref,4);
                if (!is_inside_begin_t) code.swap(code_begin_t);
                _cimg_mp_return(arg1);
              } else _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"bool(",5)) { // Boolean cast
              _cimg_mp_op("Function 'bool()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(bool,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar((bool)mem[arg1]);
              _cimg_mp_scalar1(bool,arg1);
            }

            if (!std::strncmp(ss,"break(",6)) { // Break current block
              if (pexpr[se2 - expr._data]=='(') { // no arguments?
                CImg<ulongT>::vector((ulongT)mp_break,_cimg_mp_slot_nan).move_to(code);
                _cimg_mp_return_nan();
              }
            }

            if (!std::strncmp(ss,"breakpoint(",11)) { // Break point (for abort test)
              _cimg_mp_op("Function 'breakpoint()'");
              if (pexpr[se2 - expr._data]=='(') { // no arguments?
                CImg<ulongT>::vector((ulongT)mp_breakpoint,_cimg_mp_slot_nan).move_to(code);
                _cimg_mp_return_nan();
              }
            }
            break;

          case 'c' :
            if (!std::strncmp(ss,"c2o(",4)) { // Coordinates to offset
              _cimg_mp_op("Function 'c2o()'");
              if (*ss4=='#') { // Index specified
                s0 = ss5; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss5,s0++,depth1,0,block_flags);
                p3 = 1;
                _cimg_mp_check_notnan_index(p1,ss5);
                _cimg_mp_check_list();
              } else { p1 = ~0U; s0 = ss4; p3 = 0; }
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              pos = compile(s0,s1,depth1,0,block_flags);
              p2 = size(pos);
              if (p2) { // Coordinates specified as a vector
                if (p2>4) {
                  *s1 = 0; s1 = s0;
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Argument '%s' is a vector of size %u (should be <=4), "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,s1,p2,s0);
                }
                arg1 = pos + 1;
                arg2 = p2>1?pos + 2:0;
                arg3 = p2>2?pos + 3:0;
                arg4 = p2>3?pos + 4:0;
                arg5 = s1!=se1?compile(s1 + 1,se1,depth1,0,block_flags):0; // boundary conditions
                _cimg_mp_check_type(arg5,p3 + 2,1,0);
              } else { // Coordinates specified as scalars
                arg1 = pos; arg2 = arg3 = arg4 = arg5 = 0;
                if (s1<se1) {
                  s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                  arg2 = compile(s1,s0,depth1,0,block_flags);
                  _cimg_mp_check_type(arg2,p3 + 2,1,0);
                  if (s0<se1) {
                    s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                    arg3 = compile(s0,s1,depth1,0,block_flags);
                    _cimg_mp_check_type(arg3,p3 + 3,1,0);
                    if (s1<se1) {
                      s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                      arg4 = compile(s1,s0,depth1,0,block_flags);
                      _cimg_mp_check_type(arg4,p3 + 4,1,0);
                      arg5 = s0<se1?compile(++s0,se1,depth1,0,block_flags):0; // boundary conditions
                      _cimg_mp_check_type(arg5,p3 + 5,1,0);
                    }
                  } else arg3 = 0;
                } else arg2 = 0;
              }
              _cimg_mp_scalar6(c2o,p1,arg1,arg2,arg3,arg4,arg5);
            }

            if (!std::strncmp(ss,"cabs(",5)) { // Complex absolute value
              _cimg_mp_op("Function 'cabs()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              if (is_scalar(arg1)) _cimg_mp_scalar2(complex_abs,arg1,0);
              _cimg_mp_scalar2(complex_abs,arg1 + 1,arg1 + 2);
            }

            if (!std::strncmp(ss,"carg(",5)) { // Complex argument
              _cimg_mp_op("Function 'carg()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              if (is_scalar(arg1)) _cimg_mp_scalar2(atan2,0,arg1);
              _cimg_mp_scalar2(atan2,arg1 + 2,arg1 + 1);
            }

            if (!std::strncmp(ss,"cbrt(",5)) { // Cubic root
              _cimg_mp_op("Function 'cbrt()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(cbrt,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::cbrt(mem[arg1]));
              _cimg_mp_scalar1(cbrt,arg1);
            }

            if (!std::strncmp(ss,"cconj(",6)) { // Complex conjugate
              _cimg_mp_op("Function 'cconj()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_conj,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ccos(",5)) { // Complex cosine
              _cimg_mp_op("Function 'ccos()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_cos,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ccosh(",6)) { // Complex hyperbolic cosine
              _cimg_mp_op("Function 'ccosh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_cosh,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ceil(",5)) { // Ceil
              _cimg_mp_op("Function 'ceil()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(ceil,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::ceil(mem[arg1]));
              _cimg_mp_scalar1(ceil,arg1);
            }

            if (!std::strncmp(ss,"cexp(",5)) { // Complex exponential
              _cimg_mp_op("Function 'cexp()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_exp,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"clog(",5)) { // Complex logarithm
              _cimg_mp_op("Function 'clog()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_log,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='m' && *ss2=='(') { // Image c-coordinate of minimum value
              _cimg_mp_op("Function 'cm()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_cm,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='M' && *ss2=='(') { // Image c-coordinate of maximum value
              _cimg_mp_op("Function 'cM()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_cM,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"continue(",9)) { // Continue loop
              if (pexpr[se2 - expr._data]=='(') { // no arguments?
                CImg<ulongT>::vector((ulongT)mp_continue,_cimg_mp_slot_nan).move_to(code);
                _cimg_mp_return_nan();
              }
            }

            if (!std::strncmp(ss,"convolve(",9) || !std::strncmp(ss,"correlate(",10)) { // Convolve & Correlate
              is_sth = *ss2=='n'; // is_convolve?
              _cimg_mp_op(is_sth?"Function 'convolve()'":"Function 'correlate()'");
              op = is_sth?mp_convolve:mp_correlate;
              const ulongT default_params[] = { (ulongT)op,0, // [0]=function, [1]=result vector
                0,0,0,0,0, // [2]=I, [3]=wI, [4]=hI, [5]=dI, [6]=sI
                0,0,0,0,0, // [7]=K, [8]=wK, [9]=hK, [10]=dK, [11]=sK
                1,0,1, // [12]=boundary_conditions, [13]=is_normalized, [14]=chan._mode
                ~0U,~0U,~0U, // [15]=xcenter, [16]=ycenter, [17]=zcenter
                1,1,1, // [18]=xstride, [19]=ystride, [20]=zstride
                1,1,1, // [21]=xdilation, [22]=ydilation, [23]=zdilation,
                0,0,0, // [24]=xoffset, [25]=yoffset, [26]=zoffset
                ~0U,~0U,~0U}; // [27]=xsize, [28]=ysize, [29]=zsize

              l_opcode.assign(); // Don't use 'opcode': it could be modified by further calls to 'compile()'!
              CImg<ulongT>(default_params,1,sizeof(default_params)/sizeof(ulongT)).move_to(l_opcode);

              arg1 = 2;
              for (s = std::strchr(ss,'(') + 1; s<se && arg1<l_opcode[0]._height; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                l_opcode(0,arg1++) = compile(s,ns,depth1,0,block_flags);
                s = ns;
              }
              l_opcode[0].move_to(opcode);

              if (arg1<12 || arg1>opcode._height) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: %s arguments provided, in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            arg1<12?"Not enough":"Too many",s0);
              }
              _cimg_mp_check_type(opcode[2],1,2,0); // I
              _cimg_mp_check_const_scalar(opcode[3],2,3); // wI
              _cimg_mp_check_const_scalar(opcode[4],3,3); // hI
              _cimg_mp_check_const_scalar(opcode[5],4,3); // dI
              _cimg_mp_check_const_scalar(opcode[6],5,3); // sI
              _cimg_mp_check_type(opcode[7],6,2,0); // K
              _cimg_mp_check_const_scalar(opcode[8],7,3); // wK
              _cimg_mp_check_const_scalar(opcode[9],8,3); // hK
              _cimg_mp_check_const_scalar(opcode[10],9,3); // dK
              _cimg_mp_check_const_scalar(opcode[11],10,3); // sK
              _cimg_mp_check_type(opcode[12],11,1,0); // boundary_conditions
              _cimg_mp_check_type(opcode[13],12,1,0); // is_normalized
              _cimg_mp_check_const_scalar(opcode[14],13,1); // channel_mode
              if (opcode[15]!=~0U) _cimg_mp_check_type(opcode[15],14,1,0); // xcenter
              if (opcode[16]!=~0U) _cimg_mp_check_type(opcode[16],15,1,0); // ycenter
              if (opcode[17]!=~0U) _cimg_mp_check_type(opcode[17],16,1,0); // zcenter
              _cimg_mp_check_const_scalar(opcode[18],17,3); // xstride
              _cimg_mp_check_const_scalar(opcode[19],18,3); // ystride
              _cimg_mp_check_const_scalar(opcode[20],19,3); // zstride
              _cimg_mp_check_type(opcode[21],20,1,0); // xdilation
              _cimg_mp_check_type(opcode[22],21,1,0); // ydilation
              _cimg_mp_check_type(opcode[23],22,1,0); // zdilation
              _cimg_mp_check_type(opcode[24],23,1,0); // xoffset
              _cimg_mp_check_type(opcode[25],24,1,0); // yoffset
              _cimg_mp_check_type(opcode[26],25,1,0); // zoffset
              if (opcode[27]!=~0U) _cimg_mp_check_const_scalar(opcode[27],26,3); // xsize
              if (opcode[28]!=~0U) _cimg_mp_check_const_scalar(opcode[28],27,3); // ysize
              if (opcode[29]!=~0U) _cimg_mp_check_const_scalar(opcode[29],28,3); // zsize

              const unsigned int
                wI = (unsigned int)mem[opcode[3]],
                hI = (unsigned int)mem[opcode[4]],
                dI = (unsigned int)mem[opcode[5]],
                sI = (unsigned int)mem[opcode[6]],
                wK = (unsigned int)mem[opcode[8]],
                hK = (unsigned int)mem[opcode[9]],
                dK = (unsigned int)mem[opcode[10]],
                sK = (unsigned int)mem[opcode[11]],
                channel_mode = (unsigned int)mem[opcode[14]],
                xstride = (int)mem[opcode[18]],
                ystride = (int)mem[opcode[19]],
                zstride = (int)mem[opcode[20]],
                xsize = opcode[27]==~0U?wI/xstride:(unsigned int)mem[opcode[27]],
                ysize = opcode[28]==~0U?hI/ystride:(unsigned int)mem[opcode[28]],
                zsize = opcode[29]==~0U?dI/zstride:(unsigned int)mem[opcode[29]];

              if (wI*hI*dI*sI!=size(opcode[2])) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Specified input size (%ux%ux%ux%u = %u) does "
                                            "not match size of input variable (%u), in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            wI,hI,dI,sI,wI*hI*dI*sI,size(opcode[2]),
                                            s0);
              }
              if (wK*hK*dK*sK!=size(opcode[7])) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Specified kernel size (%ux%ux%ux%u = %u) does "
                                            "not match size of kernel variable (%u), in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            wK,hK,dK,sK,wK*hK*dK*sK,size(opcode[7]),
                                            s0);
              }

              arg2 = !channel_mode?sI*sK:channel_mode==1?std::max(sI,sK):
                channel_mode==2?std::max(sI,sK)/std::min(sI,sK):1U;

              opcode[1] = pos = vector(xsize*ysize*zsize*arg2);
              opcode[3] = (ulongT)wI;
              opcode[4] = (ulongT)hI;
              opcode[5] = (ulongT)dI;
              opcode[6] = (ulongT)sI;
              opcode[8] = (ulongT)wK;
              opcode[9] = (ulongT)hK;
              opcode[10] = (ulongT)dK;
              opcode[11] = (ulongT)sK;
              opcode[14] = (ulongT)channel_mode;
              opcode[18] = (ulongT)xstride;
              opcode[19] = (ulongT)ystride;
              opcode[20] = (ulongT)zstride;
              opcode[27] = (ulongT)xsize;
              opcode[28] = (ulongT)ysize;
              opcode[29] = (ulongT)zsize;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"copy(",5)) { // Memory copy
              _cimg_mp_op("Function 'copy()'");
              ref.assign(14);
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = p1 = compile(ss5,s1,depth1,ref,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,ref._data + 7,block_flags);
              arg3 = arg4 = arg5 = ~0U; arg6 = 1;
              if (s2<se1) {
                s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                arg3 = compile(s2,s3,depth1,0,block_flags);
                if (s3<se1) {
                  s1 = ++s3; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg4 = compile(s3,s1,depth1,0,block_flags);
                  if (s1<se1) {
                    s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg5 = compile(s1,s2,depth1,0,block_flags);
                    arg6 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1;
                  }
                }
              }
              if (is_vector(arg1)) {
                if (!ref[0]) ++arg1;
                else if (ref[0]>=4 && arg4==~0U) arg4 = scalar1(mp_image_whd,ref[1]);
              }
              if (is_vector(arg2)) {
                if (arg3==~0U) arg3 = const_scalar(size(arg2));
                if (!ref[7]) ++arg2;
                if (ref[7]>=4 && arg5==~0U) arg5 = scalar1(mp_image_whd,ref[8]);
              }
              if (arg3==~0U) arg3 = 1;
              if (arg4==~0U) arg4 = 1;
              if (arg5==~0U) arg5 = 1;
              _cimg_mp_check_type(arg3,3,1,0);
              _cimg_mp_check_type(arg4,4,1,0);
              _cimg_mp_check_type(arg5,5,1,0);
              _cimg_mp_check_type(arg6,5,1,0);
              CImg<ulongT>(1,22).move_to(code);
              code.back().get_shared_rows(0,7).fill((ulongT)mp_mem_copy,p1,arg1,arg2,arg3,arg4,arg5,arg6);
              code.back().get_shared_rows(8,21).fill(ref);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"cos(",4)) { // Cosine
              _cimg_mp_op("Function 'cos()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(cos,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::cos(mem[arg1]));
              _cimg_mp_scalar1(cos,arg1);
            }

            if (!std::strncmp(ss,"cosh(",5)) { // Hyperbolic cosine
              _cimg_mp_op("Function 'cosh()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(cosh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::cosh(mem[arg1]));
              _cimg_mp_scalar1(cosh,arg1);
            }

            if (!std::strncmp(ss,"cov(",4)) { // Covariance
              _cimg_mp_op("Function 'cov()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = arg4 = ~0U;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
              }
              _cimg_mp_check_type(arg2,2,is_scalar(arg1)?1:2,size(arg1));
              if (arg3!=~0U) _cimg_mp_check_type(arg3,3,1,0);
              if (arg4!=~0U) _cimg_mp_check_type(arg4,4,1,0);
              if (arg3==~0U && arg4==~0U && size(arg1)<2) _cimg_mp_const_scalar(0);
              _cimg_mp_scalar5(cov,arg1,arg2,size(arg1),arg3,arg4);
            }

            if (!std::strncmp(ss,"critical(",9)) { // Critical section (single thread at a time)
              _cimg_mp_op("Function 'critical()'");
              p1 = code._width;
              arg1 = compile(ss + 9,se1,depth1,p_ref,block_flags | 1);
              CImg<ulongT>::vector((ulongT)mp_critical,arg1,code._width - p1).move_to(code,p1);
              _cimg_mp_return(arg1);
            }

            if (!std::strncmp(ss,"crop(",5)) { // Image or vector crop
              _cimg_mp_op("Function 'crop()'");
              is_sth = false; // is image crop ?
              arg1 = 0;
              if (*ss5=='#') { // Index specified
                s0 = ss6; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss6,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
                pos = 2;
                is_sth = true;
              } else { p1 = ~0U; s0 = ss5; need_input_copy = true; pos = 1; }
              if (s0<se1) for (s = s0; s<se; ++s, ++pos) {
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                  arg1 = compile(s,ns,depth1,0,block_flags);
                  if (pos==1 && is_scalar(arg1)) is_sth = true;
                  else if (pos>1) _cimg_mp_check_type(arg1,pos,1,0);
                  CImg<ulongT>::vector(arg1).move_to(l_opcode);
                  s = ns;
                }
              (l_opcode>'y').move_to(opcode);

              if (!opcode || is_sth) { // Image crop
                arg1 = 0; arg2 = (p1!=~0U);
                switch (opcode._height) {
                case 0 : case 1 :
                  CImg<ulongT>::vector(0,0,0,0,~0U,~0U,~0U,~0U,0).move_to(opcode);
                  break;
                case 2 :
                  CImg<ulongT>::vector(*opcode,0,0,0,opcode[1],~0U,~0U,~0U,_cimg_mp_boundary).move_to(opcode);
                  arg1 = 2 + arg2; break;
                case 3 :
                  CImg<ulongT>::vector(*opcode,0,0,0,opcode[1],~0U,~0U,~0U,opcode[2]).move_to(opcode);
                  arg1 = 2 + arg2; break;
                case 4 :
                  CImg<ulongT>::vector(*opcode,opcode[1],0,0,opcode[2],opcode[3],~0U,~0U,_cimg_mp_boundary).
                    move_to(opcode);
                  arg1 = 3 + arg2; break;
                case 5 :
                  CImg<ulongT>::vector(*opcode,opcode[1],0,0,opcode[2],opcode[3],~0U,~0U,opcode[4]).
                    move_to(opcode);
                  arg1 = 3 + arg2; break;
                case 6 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],0,opcode[3],opcode[4],opcode[5],~0U,
                                       _cimg_mp_boundary).move_to(opcode);
                  arg1 = 4 + arg2; break;
                case 7 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],0,opcode[3],opcode[4],opcode[5],~0U,
                                       opcode[6]).move_to(opcode);
                  arg1 = 4 + arg2; break;
                case 8 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],opcode[5],opcode[6],
                                       opcode[7],_cimg_mp_boundary).move_to(opcode);
                  arg1 = 5 + arg2; break;
                case 9 :
                  arg1 = 5 + arg2; break;
                default : // Error -> too many arguments
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Too many arguments specified, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,s0);
                }

                if (opcode[4]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[4],arg1,3);
                  opcode[4] = (ulongT)mem[opcode[4]];
                }
                if (opcode[5]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[5],arg1 + 1,3);
                  opcode[5] = (ulongT)mem[opcode[5]];
                }
                if (opcode[6]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[6],arg1 + 2,3);
                  opcode[6] = (ulongT)mem[opcode[6]];
                }
                if (opcode[7]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[7],arg1 + 3,3);
                  opcode[7] = (ulongT)mem[opcode[7]];
                }
                _cimg_mp_check_type((unsigned int)opcode[8],arg1 + 4,1,0);

                if (opcode[4]==(ulongT)~0U || opcode[5]==(ulongT)~0U ||
                    opcode[6]==(ulongT)~0U || opcode[7]==(ulongT)~0U) {
                  p2 = 0;
                  if (p1!=~0U) {
                    _cimg_mp_check_const_scalar(p1,1,1);
                    p2 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
                  }
                  const CImg<T> &img = p1!=~0U?imglist[p2]:imgin;
                  if (!img) {
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Cannot crop empty image when "
                                                "some xyzc-coordinates are unspecified, in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,s0);
                  }
                  if (opcode[4]==(ulongT)~0U) opcode[4] = (ulongT)img._width;
                  if (opcode[5]==(ulongT)~0U) opcode[5] = (ulongT)img._height;
                  if (opcode[6]==(ulongT)~0U) opcode[6] = (ulongT)img._depth;
                  if (opcode[7]==(ulongT)~0U) opcode[7] = (ulongT)img._spectrum;
                }

                pos = vector((unsigned int)(opcode[4]*opcode[5]*opcode[6]*opcode[7]));
                CImg<ulongT>::vector((ulongT)mp_image_crop,
                                     pos,p1, // 1-2: res,#ind
                                     *opcode,opcode[1],opcode[2],opcode[3], // 3-6: x,y,z,c
                                     opcode[4],opcode[5],opcode[6],opcode[7], // 7-10: dx,dy,dz,dc
                                     opcode[8]).move_to(code); // 11: boundary conditions

              } else { // Vector crop
                switch (opcode._height) {
                case 5 : case 6 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       0,0,0,0,~0U,~0U,~0U,~0U,0).move_to(opcode);
                  break;
                case 7 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],0,0,0,opcode[6],~0U,~0U,~0U,_cimg_mp_boundary).move_to(opcode);
                  arg1 = 7; break;
                case 8 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],0,0,0,opcode[6],~0U,~0U,~0U,opcode[7]).move_to(opcode);
                  arg1 = 7; break;
                case 9 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],opcode[6],0,0,opcode[7],opcode[8],~0U,~0U,_cimg_mp_boundary).
                    move_to(opcode);
                  arg1 = 8; break;
                case 10 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],opcode[6],0,0,opcode[7],opcode[8],~0U,~0U,opcode[9]).
                    move_to(opcode);
                  arg1 = 8; break;
                case 11 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],opcode[6],opcode[7],0,opcode[8],opcode[9],opcode[10],~0U,
                                       _cimg_mp_boundary).move_to(opcode);
                  arg1 = 9; break;
                case 12 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],opcode[6],opcode[7],0,opcode[8],opcode[9],opcode[10],~0U,
                                       opcode[11]).move_to(opcode);
                  arg1 = 9; break;
                case 13 :
                  CImg<ulongT>::vector(*opcode,opcode[1],opcode[2],opcode[3],opcode[4],
                                       opcode[5],opcode[6],opcode[7],opcode[8],opcode[9],opcode[10],opcode[11],
                                       opcode[12],_cimg_mp_boundary).move_to(opcode);
                  arg1 = 10; break;
                case 14 :
                  arg1 = 10; break;
                default : // Error -> too few or too many arguments
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Too %s arguments specified, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              opcode._height<5?"few":"much",s0);
                }

                _cimg_mp_check_const_scalar((unsigned int)opcode[1],2,3); // w
                opcode[1] = (ulongT)mem[opcode[1]];
                _cimg_mp_check_const_scalar((unsigned int)opcode[2],3,3); // h
                opcode[2] = (ulongT)mem[opcode[2]];
                _cimg_mp_check_const_scalar((unsigned int)opcode[3],4,3); // d
                opcode[3] = (ulongT)mem[opcode[3]];
                _cimg_mp_check_const_scalar((unsigned int)opcode[4],5,3); // s
                opcode[4] = (ulongT)mem[opcode[4]];
                p1 = size((unsigned int)opcode[0]);
                arg2 = (unsigned int)opcode[1];
                arg3 = (unsigned int)opcode[2];
                arg4 = (unsigned int)opcode[3];
                arg5 = (unsigned int)opcode[4];
                if (arg2*arg3*arg4*arg5!=p1) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                              "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              p1,arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
                }
                if (opcode[9]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[9],arg1,3);
                  opcode[9] = (ulongT)mem[opcode[9]];
                } else opcode[9] = opcode[1];
                if (opcode[10]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[10],arg1 + 1,3);
                  opcode[10] = (ulongT)mem[opcode[10]];
                } else opcode[10] = opcode[2];
                if (opcode[11]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[11],arg1 + 2,3);
                  opcode[11] = (ulongT)mem[opcode[11]];
                } else opcode[11] = opcode[3];
                if (opcode[12]!=(ulongT)~0U) {
                  _cimg_mp_check_const_scalar((unsigned int)opcode[12],arg1 + 3,3);
                  opcode[12] = (ulongT)mem[opcode[12]];
                } else opcode[12] = opcode[4];
                _cimg_mp_check_type((unsigned int)opcode[13],arg1 + 4,1,0);

                pos = vector((unsigned int)(opcode[9]*opcode[10]*opcode[11]*opcode[12]));
                CImg<ulongT>::vector((ulongT)mp_vector_crop_ext,
                                     pos,*opcode, // 1-2: res,S
                                     opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                     opcode[5],opcode[6],opcode[7],opcode[8], // 7-10: x,y,z,c
                                     opcode[9],opcode[10],opcode[11],opcode[12], // 11-14: dx,dy,dz,dc
                                     opcode[13]).move_to(code); // 15: boundary conditions
              }
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"cross(",6)) { // Cross product
              _cimg_mp_op("Function 'cross()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,3);
              _cimg_mp_check_type(arg2,2,2,3);
              pos = vector(3);
              CImg<ulongT>::vector((ulongT)mp_cross,pos,arg1,arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"csin(",5)) { // Complex sine
              _cimg_mp_op("Function 'csin()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_sin,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"csinh(",6)) { // Complex hyperbolic sine
              _cimg_mp_op("Function 'csinh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_sinh,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"csqr(",5)) { // Complex square
              _cimg_mp_op("Function 'csqr()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_sqr,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"csqrt(",6)) { // Complex square root
              _cimg_mp_op("Function 'csqrt()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_sqrt,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ctan(",5)) { // Complex tangent
              _cimg_mp_op("Function 'ctan()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_tan,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ctanh(",6)) { // Complex hyperbolic tangent
              _cimg_mp_op("Function 'ctanh()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,0,3,2);
              pos = vector(2);
              if (is_scalar(arg1)) {
                CImg<ulongT>::vector((ulongT)mp_vector_init,pos,2,2,0,arg1,0,0).move_to(code);
                arg1 = pos;
              }
              CImg<ulongT>::vector((ulongT)mp_complex_tanh,pos,2,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"cumulate(",9)) { // Cumulate
              _cimg_mp_op("Function 'cumulate()'");
              s0 = ss + 9;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              p1 = size(arg1);
              arg2 = p1;
              arg3 = arg4 = arg5 = 1;
              arg6 = p2 = ~0U;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg4 = compile(s1,s2,depth1,0,block_flags);
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg5 = compile(s2,s1,depth1,0,block_flags);
                arg6 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
                _cimg_mp_check_const_scalar(arg2,2,3);
                _cimg_mp_check_const_scalar(arg3,3,3);
                _cimg_mp_check_const_scalar(arg4,4,3);
                _cimg_mp_check_const_scalar(arg5,5,3);
                arg2 = (unsigned int)mem[arg2];
                arg3 = (unsigned int)mem[arg3];
                arg4 = (unsigned int)mem[arg4];
                arg5 = (unsigned int)mem[arg5];
                p2 = arg6!=~0U?size(arg6):~0U;
              }
              if (arg2*arg3*arg4*arg5!=std::max(1U,p1)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                            "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p1,1U),arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
              }
              pos = vector(arg2*arg3*arg4*arg5);
              CImg<ulongT>::vector((ulongT)mp_cumulate,pos,arg1,arg2,arg3,arg4,arg5,arg6,p2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"cut(",4)) { // Cut
              _cimg_mp_op("Function 'cut()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):const_scalar(cimg::type<double>::inf());
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              if (is_vector(arg1)) _cimg_mp_vector3(cut,arg1,arg2,arg3);
              if (is_const_scalar(arg1) && is_const_scalar(arg2) && is_const_scalar(arg3)) {
                val = mem[arg1];
                val1 = mem[arg2];
                val2 = mem[arg3];
                _cimg_mp_const_scalar(cimg::cut(val,val1,val2));
              }
              _cimg_mp_scalar3(cut,arg1,arg2,arg3);
            }
            break;

          case 'd' :
            if (*ss1=='(') { // Image depth
              _cimg_mp_op("Function 'd()'");
              if (*ss2=='#') { // Index specified
                p1 = compile(ss3,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss3);
                _cimg_mp_check_list();
              } else { if (ss2!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_depth,p1);
            }

            if (!std::strncmp(ss,"da_back(",8) ||
                !std::strncmp(ss,"da_pop(",7) ||
                !std::strncmp(ss,"da_pop_heap(",12)) { // Get latest element in a dynamic array
              if (!is_inside_critical) is_parallelizable = false;
              const bool is_pop = *ss3=='p', is_pop_heap = *ss6=='_';
              _cimg_mp_op(is_pop_heap?"Function 'da_pop_heap()":
                          is_pop?"Function 'da_pop()'":"Function 'da_back()'");
              s0 = ss + (is_pop_heap?12:is_pop?7:8);
              if (*s0=='#') { // Index specified
                s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                p1 = compile(s0,s1++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,s0);
              } else { p1 = 11; s1 = s0; } // Default: #-1
              _cimg_mp_check_list();
              _cimg_mp_check_const_scalar(p1,1,1);
              p3 = (unsigned int)cimg::mod((int)mem[p1],imglist.width());
              p2 = imglist[p3]._spectrum;
              if (p2>1) pos = vector(p2); else pos = scalar(); // Return vector or scalar result
              CImg<ulongT>::vector((ulongT)mp_da_back_or_pop,pos,p2,p1,is_pop_heap?2:is_pop?1:0).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"da_freeze(",10)) { // Freeze dynamic array
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'da_freeze()'");
              s0 = ss + 10;
              if (*s0=='#') { // Index specified
                s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                p1 = compile(s0,s1++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,s0);
              } else { p1 = 11; s1 = s0; } // Default: #-1
              _cimg_mp_check_list();
              CImg<ulongT>::vector((ulongT)mp_da_freeze,_cimg_mp_slot_nan,p1).move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"da_insert(",10) ||
                !std::strncmp(ss,"da_insert_n(",12) ||
                !std::strncmp(ss,"da_push(",8) ||
                !std::strncmp(ss,"da_push_n(",10) ||
                !std::strncmp(ss,"da_push_heap(",13) ||
                !std::strncmp(ss,"da_push_heap_n(",15)) { // Insert element(s) in a dynamic array
              if (!is_inside_critical) is_parallelizable = false;
              const bool
                is_push_heap = *ss3=='p' && *ss7=='_' && *ss8=='h',
                is_push = !is_push_heap && *ss3=='p',
                is_insert = !is_push_heap && !is_push,
                is_n = is_push_heap?ss[12]=='_':is_push?*ss7=='_':ss[9]=='_';
              _cimg_mp_op(is_push_heap?(is_n?"Function 'da_push_heap_n()'":"Function 'da_push_heap()'"):
                          is_push?(is_n?"Function 'da_push_n()'":"Function 'da_push()'"):
                          (is_n?"Function 'da_insert_n()'":"Function 'da_insert()'"));
              s0 = ss + (is_push_heap?13:is_push?8:10) + (is_n?2:0);
              if (*s0=='#') { // Index specified
                s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                p1 = compile(s0,s1++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,s0);
              } else { p1 = 11; s1 = s0; } // Default: #-1
              _cimg_mp_check_list();
              if (is_n) {
                s0 = s1; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg1 = compile(s0,s1++,depth1,0,block_flags); // Count
              } else arg1 = ~0U;
              if (is_insert) {
                s0 = s1; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg2 = compile(s0,s1++,depth1,0,block_flags); // Position
              } else if (is_push_heap) arg2 = ~0U - 1;
              else arg2 = ~0U;
              CImg<ulongT>::vector((ulongT)mp_da_insert_or_push_n,_cimg_mp_slot_nan,p1,arg1,arg2,0,0).move_to(l_opcode);
              pos = (p1==~0U?2:3) + (is_n?1:0) + (is_insert?1:0);
              p1 = ~0U;
              for (s = s1; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg3 = compile(s,ns,depth1,0,block_flags); // Element
                p3 = size(arg3);
                if (p1==~0U) p1 = p3;
                else {
                  if (!p1) _cimg_mp_check_type(arg3,pos,1,0);
                  else _cimg_mp_check_type(arg3,pos,2,p1);
                }
                CImg<ulongT>::vector(arg3).move_to(l_opcode);
                s = ns;
                ++pos;
              }
              if (p1==~0U && !is_n) compile(++s1,se1,depth1,0,block_flags); // Missing element -> error, if !is_n
              (l_opcode>'y').move_to(opcode);
              opcode[5] = p1;
              opcode[6] = opcode._height - 7;
              opcode.move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"da_remove(",10)) { // Remove element(s) in a dynamic array
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'da_remove()'");
              if (ss[10]=='#') { // Index specified
                s0 = ss + 11; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss + 11,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss + 11);
              } else { p1 = 11; s0 = ss + 10; } // Default: #-1
              _cimg_mp_check_list();

              arg1 = arg2 = ~0U;
              if (s0<se1) {
                s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg1 = compile(s0,s1,depth1,0,block_flags); // Starting position
                arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U; // Ending position
              }
              CImg<ulongT>::vector((ulongT)mp_da_remove,_cimg_mp_slot_nan,p1,arg1,arg2).move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"da_size(",8)) { // Size of a dynamic array
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'da_size()'");
              if (ss[8]=='#') { // Index specified
                s0 = ss + 9; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss + 9,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss + 9);
              } else { p1 = 11; s0 = ss + 8; } // Default: #-1
              _cimg_mp_check_list();
              _cimg_mp_scalar1(da_size,p1);
            }

            if (!std::strncmp(ss,"date(",5)) { // Current date or file date
              _cimg_mp_op("Function 'date()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = ss5!=se1?compile(ss5,s1,depth1,0,block_flags):~0U;
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
              if (arg2!=~0U) _cimg_mp_check_type(arg2,1,2,0);
              pos = arg1==~0U || is_vector(arg1)?vector(arg1==~0U?7:size(arg1)):scalar();
              CImg<ulongT>::vector((ulongT)mp_date,pos,size(pos),
                                   arg1,arg1==~0U?~0U:size(arg1),
                                   arg2,arg2==~0U?~0U:size(arg2)).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"debug(",6)) { // Print debug info
              _cimg_mp_op("Function 'debug()'");
              p1 = code._width;
              arg1 = compile(ss6,se1,depth1,p_ref,block_flags);
              *se1 = 0;
              variable_name.assign(CImg<charT>::string(ss6,true,true).unroll('y'),true);
              cimg::strpare(variable_name,false,true);
              ((CImg<ulongT>::vector((ulongT)mp_debug,arg1,0,code._width - p1),
                variable_name)>'y').move_to(opcode);
              opcode[2] = opcode._height - 4;
              opcode.move_to(code,p1);
              *se1 = ')';
              _cimg_mp_return(arg1);
            }

            if (!std::strncmp(ss,"deg2rad(",8)) { // Degrees to radians
              _cimg_mp_op("Function 'deg2rad()'");
              arg1 = compile(ss8,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(deg2rad,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(mem[arg1]*cimg::PI/180);
              _cimg_mp_scalar1(deg2rad,arg1);
            }

            if (!std::strncmp(ss,"det(",4)) { // Matrix determinant
              _cimg_mp_op("Function 'det()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              _cimg_mp_check_matrix_square(arg1,1);
              p1 = (unsigned int)cimg::round(std::sqrt((float)size(arg1)));
              _cimg_mp_scalar2(det,arg1,p1);
            }

            if (!std::strncmp(ss,"diag(",5)) { // Diagonal matrix
              _cimg_mp_op("Function 'diag()'");
              CImg<ulongT>::vector((ulongT)mp_diag,0,0).move_to(l_opcode);
              for (s = ss5; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                if (is_vector(arg2))
                  CImg<ulongT>::sequence(size(arg2),arg2 + 1,arg2 + (ulongT)size(arg2)).move_to(l_opcode);
                else
                  CImg<ulongT>::vector(arg2).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              arg1 = opcode._height - 3;
              pos = vector(arg1*arg1);
              opcode[1] = pos;
              opcode[2] = arg1;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"display(",8)) { // Display memory, vector or image
              _cimg_mp_op("Function 'display()'");
              if (pexpr[se2 - expr._data]=='(') { // no arguments?
                CImg<ulongT>::vector((ulongT)mp_mem_display,_cimg_mp_slot_nan).move_to(code);
                _cimg_mp_return_nan();
              }
              if (*ss8!='#') { // Vector
                s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg1 = compile(ss8,s1,depth1,0,block_flags);
                arg2 = 0; arg3 = arg4 = arg5 = 1;
                if (s1<se1) {
                  s2 = s1 + 1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg2 = compile(s1 + 1,s2,depth1,0,block_flags);
                  if (s2<se1) {
                    s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                    arg3 = compile(s2,s3,depth1,0,block_flags);
                    if (s3<se1) {
                      s2 = ++s3; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                      arg4 = compile(s3,s2,depth1,0,block_flags);
                      arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1;
                    }
                  }
                }
                _cimg_mp_check_type(arg2,2,1,0);
                _cimg_mp_check_type(arg3,3,1,0);
                _cimg_mp_check_type(arg4,4,1,0);
                _cimg_mp_check_type(arg5,5,1,0);

                c1 = *s1; *s1 = 0;
                variable_name.assign(CImg<charT>::string(ss8,true,true).unroll('y'),true);
                cimg::strpare(variable_name,false,true);
                if (is_vector(arg1))
                  ((CImg<ulongT>::vector((ulongT)mp_vector_print,arg1,0,(ulongT)size(arg1),0),
                    variable_name)>'y').move_to(opcode);
                else
                  ((CImg<ulongT>::vector((ulongT)mp_print,arg1,0,0),
                    variable_name)>'y').move_to(opcode);
                opcode[2] = opcode._height;
                opcode.move_to(code);

                ((CImg<ulongT>::vector((ulongT)mp_vector_display,arg1,0,(ulongT)size(arg1),
                                       arg2,arg3,arg4,arg5),
                  variable_name)>'y').move_to(opcode);
                opcode[2] = opcode._height - 8;
                opcode.move_to(code);
                *s1 = c1;
                _cimg_mp_return(arg1);

              } else { // Image
                p1 = compile(ss8 + 1,se1,depth1,0,block_flags);
                _cimg_mp_check_list();
                CImg<ulongT>::vector((ulongT)mp_image_display,_cimg_mp_slot_nan,p1).move_to(code);
                _cimg_mp_return_nan();
              }
            }

            if (!std::strncmp(ss,"do(",3)) { // Do..while
              _cimg_mp_op("Function 'do()'");
              s0 = *ss2=='('?ss3:ss8;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = code._width;
              arg6 = mempos;
              p1 = compile(s0,s1,depth1,0,block_flags); // Body
              arg2 = code._width;
              p2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1; // Condition
              _cimg_mp_check_type(p2,2,1,0);
              CImg<ulongT>::vector((ulongT)mp_do,p1,p2,arg2 - arg1,code._width - arg2,size(p1),
                                   p1>=arg6 && !is_const_scalar(p1),
                                   p2>=arg6 && !is_const_scalar(p2)).move_to(code,arg1);
              _cimg_mp_return(p1);
            }

            if (!std::strncmp(ss,"dot(",4)) { // Dot product
              _cimg_mp_op("Function 'dot()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              if (is_vector(arg1)) {
                _cimg_mp_check_type(arg2,2,2,size(arg1));
                _cimg_mp_scalar3(dot,arg1,arg2,size(arg1));
              }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_scalar2(mul,arg1,arg2);
            }

            if (!std::strncmp(ss,"draw(",5)) { // Draw image
              _cimg_mp_op("Function 'draw()'");
              if (*ss5=='#') { // Index specified
                s0 = ss6; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss6,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
              } else { p1 = ~0U; s0 = ss5; }

              for (s = s0; s<se; ++s, ++pos) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg1 = compile(s,ns,depth1,0,block_flags);
                CImg<ulongT>::vector(arg1).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);

              is_sth = p1==~0U && opcode._height>5 && is_vector((unsigned int)opcode[5]); // Is vector drawing?
              if ((is_sth && (opcode._height<6 || opcode._height>17)) ||
                  (!is_sth && (opcode._height<1 || opcode._height>12))) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Too %s arguments specified, "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            opcode._height>12?"much":"few",s0);
              }

              if (is_sth) { // Drawing in a vector
                _cimg_mp_check_type((unsigned int)*opcode,1,2,0); // D
                _cimg_mp_check_type((unsigned int)opcode[1],2,1,0); // w
                _cimg_mp_check_type((unsigned int)opcode[2],3,1,0); // h
                _cimg_mp_check_type((unsigned int)opcode[3],4,1,0); // d
                _cimg_mp_check_type((unsigned int)opcode[4],5,1,0); // s

                if (opcode._height<8 || (opcode._height<10 && is_vector((unsigned int)opcode[7]))) {
                  // D,w,h,d,s,S[,opac,M,maxM].
                  if (opcode._height>6) _cimg_mp_check_type((unsigned int)opcode[6],7,1,0); // opac
                  if (opcode._height>8) _cimg_mp_check_type((unsigned int)opcode[8],9,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_vector_draw,
                                       *opcode,size((unsigned int)*opcode), // 1-2: D,sizD
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                       opcode[5],size((unsigned int)opcode[5]), // 7-8: S,sizS
                                       0,0,0,0, // 9-12: x,y,z,c
                                       ~0U,~0U,~0U,~0U, // 13-16: dx,dy,dz,dc
                                       opcode._height<7?1:opcode[6], // 17: opac
                                       opcode._height<8?~0U:opcode[7], // 18: M
                                       opcode._height<8?0:size((unsigned int)opcode[7]), // 19: sizM
                                       opcode._height<9?1:opcode[8]).move_to(code); // 20: maxM
                } else if (opcode._height<10 || (opcode._height<12 && is_vector((unsigned int)opcode[9]))) {
                  // D,w,h,d,s,S,x,dx[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[6],7,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[7],8,1,0); // dx
                  if (opcode._height>8) _cimg_mp_check_type((unsigned int)opcode[8],9,1,0); // opac
                  if (opcode._height>10) _cimg_mp_check_type((unsigned int)opcode[10],11,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_vector_draw,
                                       *opcode,size((unsigned int)*opcode), // 1-2: D,sizD
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                       opcode[5],size((unsigned int)opcode[5]), // 7-8: S,sizS
                                       opcode[6],0,0,0, // 9-12: x,y,z,c
                                       opcode[7],~0U,~0U,~0U, // 13-16: dx,dy,dz,dc
                                       opcode._height<9?1:opcode[8], // 17: opac
                                       opcode._height<10?~0U:opcode[9], // 18: M
                                       opcode._height<10?0:size((unsigned int)opcode[9]), // 19: sizM
                                       opcode._height<11?1:opcode[10]).move_to(code); // 20: maxM
                } else if (opcode._height<12 || (opcode._height<14 && is_vector((unsigned int)opcode[11]))) {
                  // D,w,h,d,s,S,x,y,dx,dy[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[6],7,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[7],8,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[8],9,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[9],10,1,0); // dy
                  if (opcode._height>10) _cimg_mp_check_type((unsigned int)opcode[10],11,1,0); // opac
                  if (opcode._height>12) _cimg_mp_check_type((unsigned int)opcode[12],13,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_vector_draw,
                                       *opcode,size((unsigned int)*opcode), // 1-2: D,sizD
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                       opcode[5],size((unsigned int)opcode[5]), // 7-8: S,sizS
                                       opcode[6],opcode[7],0,0, // 9-12: x,y,z,c
                                       opcode[8],opcode[9],~0U,~0U, // 13-16: dx,dy,dz,dc
                                       opcode._height<11?1:opcode[10], // 17: opac
                                       opcode._height<12?~0U:opcode[11], // 18: M
                                       opcode._height<12?0:size((unsigned int)opcode[11]), // 19: sizM
                                       opcode._height<13?1:opcode[12]).move_to(code); // 20: maxM
                } else if (opcode._height<14 || (opcode._height<16 && is_vector((unsigned int)opcode[13]))) {
                  // D,w,h,d,s,S,x,y,z,dx,dy,dz[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[6],7,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[7],8,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[8],9,1,0); // z
                  _cimg_mp_check_type((unsigned int)opcode[9],10,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[10],11,1,0); // dy
                  _cimg_mp_check_type((unsigned int)opcode[11],12,1,0); // dz
                  if (opcode._height>12) _cimg_mp_check_type((unsigned int)opcode[12],13,1,0); // opac
                  if (opcode._height>14) _cimg_mp_check_type((unsigned int)opcode[14],15,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_vector_draw,
                                       *opcode,size((unsigned int)*opcode), // 1-2: D,sizD
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                       opcode[5],size((unsigned int)opcode[5]), // 7-8: S,sizS
                                       opcode[6],opcode[7],opcode[8],0, // 9-12: x,y,z,c
                                       opcode[9],opcode[10],opcode[11],~0U, // 13-16: dx,dy,dz,dc
                                       opcode._height<13?1:opcode[12], // 17: opac
                                       opcode._height<14?~0U:opcode[13], // 18: M
                                       opcode._height<14?0:size((unsigned int)opcode[13]), // 19: sizM
                                       opcode._height<15?1:opcode[14]).move_to(code); // 20: maxM
                } else if (opcode._height<16 || (opcode._height<18 && is_vector((unsigned int)opcode[15]))) {
                  // D,w,h,d,s,S,x,y,z,c,dx,dy,dz,dc[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[6],7,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[7],8,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[8],9,1,0); // z
                  _cimg_mp_check_type((unsigned int)opcode[9],10,1,0); // c
                  _cimg_mp_check_type((unsigned int)opcode[10],11,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[11],12,1,0); // dy
                  _cimg_mp_check_type((unsigned int)opcode[12],13,1,0); // dz
                  _cimg_mp_check_type((unsigned int)opcode[13],14,1,0); // dc
                  if (opcode._height>14) _cimg_mp_check_type((unsigned int)opcode[14],15,1,0); // opac
                  if (opcode._height>16) _cimg_mp_check_type((unsigned int)opcode[16],17,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_vector_draw,
                                       *opcode,size((unsigned int)*opcode), // 1-2: D,sizD
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 3-6: w,h,d,s
                                       opcode[5],size((unsigned int)opcode[5]), // 7-8: S,sizS
                                       opcode[6],opcode[7],opcode[8],opcode[9], // 9-12: x,y,z,c
                                       opcode[10],opcode[11],opcode[12],opcode[13], // 13-16: dx,dy,dz,dc
                                       opcode._height<15?1:opcode[14], // 17: opac
                                       opcode._height<16?~0U:opcode[15], // 18: M
                                       opcode._height<16?0:size((unsigned int)opcode[15]), // 19: sizM
                                       opcode._height<17?1:opcode[16]).move_to(code); // 20: maxM
                } else {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Invalid types in specified arguments, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,s0);
                }

              } else { // Drawing in an image
                if (!is_inside_critical) is_parallelizable = false;
                arg1 = p1!=~0U;
                _cimg_mp_check_type((unsigned int)*opcode,1 + arg1,2,0); // S
                if (opcode._height<3 || (opcode._height<5 && is_vector((unsigned int)opcode[2]))) {
                  // S[,opac,M,maxM].
                  if (opcode._height>1) _cimg_mp_check_type((unsigned int)opcode[1],2 + arg1,1,0); // opac
                  if (opcode._height>3) _cimg_mp_check_type((unsigned int)opcode[3],4 + arg1,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_image_draw,
                                       *opcode,size((unsigned int)*opcode),p1, // 1-3: S,sizS,#ind
                                       0,0,0,0, // 4-7: x,y,z,c
                                       ~0U,~0U,~0U,~0U, // 8-11: dx,dy,dz,dc
                                       opcode._height<2?1:opcode[1], // 12: opac
                                       opcode._height<3?~0U:opcode[2], // 13: M
                                       opcode._height<3?0:size((unsigned int)opcode[2]), // 14: sizM
                                       opcode._height<4?1:opcode[3]).move_to(code); // 15: maxM
                } else if (opcode._height<5 || (opcode._height<7 && is_vector((unsigned int)opcode[4]))) {
                  // x,dx,S[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[1],2 + arg1,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[2],3 + arg1,1,0); // dx
                  if (opcode._height>3) _cimg_mp_check_type((unsigned int)opcode[3],4 + arg1,1,0); // opac
                  if (opcode._height>5) _cimg_mp_check_type((unsigned int)opcode[5],6 + arg1,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_image_draw,
                                       *opcode,size((unsigned int)*opcode),p1, // 1-3: S,sizS,#ind
                                       opcode[1],0,0,0, // 4-7: x,y,z,c
                                       opcode[2],~0U,~0U,~0U, // 8-11: dx,dy,dz,dc
                                       opcode._height<4?1:opcode[3], // 12: opac
                                       opcode._height<5?~0U:opcode[4], // 13: M
                                       opcode._height<5?0:size((unsigned int)opcode[4]), // 14: sizM
                                       opcode._height<6?1:opcode[5]).move_to(code); // 15: maxM
                } else if (opcode._height<7 || (opcode._height<9 && is_vector((unsigned int)opcode[6]))) {
                  // x,y,dx,dy,S[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[1],2 + arg1,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[2],3 + arg1,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[3],4 + arg1,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[4],5 + arg1,1,0); // dy
                  if (opcode._height>5) _cimg_mp_check_type((unsigned int)opcode[5],6 + arg1,1,0); // opac
                  if (opcode._height>7) _cimg_mp_check_type((unsigned int)opcode[7],8 + arg1,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_image_draw,
                                       *opcode,size((unsigned int)*opcode),p1, // 1-3: S,sizS,#ind
                                       opcode[1],opcode[2],0,0, // 4-7: x,y,z,c
                                       opcode[3],opcode[4],~0U,~0U, // 8-11: dx,dy,dz,dc
                                       opcode._height<6?1:opcode[5], // 12: opac
                                       opcode._height<7?~0U:opcode[6], // 13: M
                                       opcode._height<7?0:size((unsigned int)opcode[6]), // 14: sizM
                                       opcode._height<8?1:opcode[7]).move_to(code); // 15: maxM
                } else if (opcode._height<9 || (opcode._height<11 && is_vector((unsigned int)opcode[8]))) {
                  // x,y,z,dx,dy,dz,S[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[1],2 + arg1,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[2],3 + arg1,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[3],4 + arg1,1,0); // z
                  _cimg_mp_check_type((unsigned int)opcode[4],5 + arg1,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[5],6 + arg1,1,0); // dy
                  _cimg_mp_check_type((unsigned int)opcode[6],7 + arg1,1,0); // dz
                  if (opcode._height>7) _cimg_mp_check_type((unsigned int)opcode[7],8 + arg1,1,0); // opac
                  if (opcode._height>9) _cimg_mp_check_type((unsigned int)opcode[9],10 + arg1,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_image_draw,
                                       *opcode,size((unsigned int)*opcode),p1, // 1-3: S,sizS,#ind
                                       opcode[1],opcode[2],opcode[3],0, // 4-7: x,y,z,c
                                       opcode[4],opcode[5],opcode[6],~0U, // 8-11: dx,dy,dz,dc
                                       opcode._height<8?1:opcode[7], // 12: opac
                                       opcode._height<9?~0U:opcode[8], // 13: M
                                       opcode._height<9?0:size((unsigned int)opcode[8]), // 14: sizM
                                       opcode._height<10?1:opcode[9]).move_to(code); // 15: maxM
                } else if (opcode._height<11 || (opcode._height<13 && is_vector((unsigned int)opcode[10]))) {
                  // x,y,z,c,dx,dy,dz,dc,S[,opac,M,maxM].
                  _cimg_mp_check_type((unsigned int)opcode[1],2 + arg1,1,0); // x
                  _cimg_mp_check_type((unsigned int)opcode[2],3 + arg1,1,0); // y
                  _cimg_mp_check_type((unsigned int)opcode[3],4 + arg1,1,0); // z
                  _cimg_mp_check_type((unsigned int)opcode[4],5 + arg1,1,0); // c
                  _cimg_mp_check_type((unsigned int)opcode[5],6 + arg1,1,0); // dx
                  _cimg_mp_check_type((unsigned int)opcode[6],7 + arg1,1,0); // dy
                  _cimg_mp_check_type((unsigned int)opcode[7],8 + arg1,1,0); // dz
                  _cimg_mp_check_type((unsigned int)opcode[8],9 + arg1,1,0); // dc
                  if (opcode._height>9) _cimg_mp_check_type((unsigned int)opcode[9],10 + arg1,1,0); // opac
                  if (opcode._height>11) _cimg_mp_check_type((unsigned int)opcode[11],12 + arg1,1,0); // maxM
                  CImg<ulongT>::vector((ulongT)mp_image_draw,
                                       *opcode,size((unsigned int)*opcode),p1, // 1-3: S,sizS,#ind
                                       opcode[1],opcode[2],opcode[3],opcode[4], // 4-7: x,y,z,c
                                       opcode[5],opcode[6],opcode[7],opcode[8], // 8-11: dx,dy,dz,dc
                                       opcode._height<10?1:opcode[9], // 12: opac
                                       opcode._height<11?~0U:opcode[10], // 13: M
                                       opcode._height<11?0:size((unsigned int)opcode[10]), // 14: sizM
                                       opcode._height<12?1:opcode[11]).move_to(code); // 15: maxM
                } else {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Invalid types in specified arguments, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,s0);
                }
              }
              _cimg_mp_return_nan();
            }
            break;

          case 'e' :
            if (!std::strncmp(ss,"echo(",5)) { // Echo
              _cimg_mp_op("Function 'echo()'");
              CImg<ulongT>::vector((ulongT)mp_echo,_cimg_mp_slot_nan,0).move_to(l_opcode);
              for (s = ss5; s<se1; ++s) {
                ns = s; while (ns<se1 && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg1 = compile(s,ns,depth1,0,block_flags);
                CImg<ulongT>::vector(arg1,size(arg1)).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              opcode[2] = (opcode._height - 3)/2;
              opcode.move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"eig(",4)) { // Matrix eigenvalues/eigenvector
              _cimg_mp_op("Function 'eig()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              _cimg_mp_check_matrix_square(arg1,1);
              p1 = (unsigned int)cimg::round(std::sqrt((float)size(arg1)));
              pos = vector((p1 + 1)*p1);
              CImg<ulongT>::vector((ulongT)mp_matrix_eigen,pos,arg1,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ellipse(",8)) { // Ellipse/circle drawing
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'ellipse()'");
              if (*ss8=='#') { // Index specified
                s0 = ss + 9; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss + 9,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss + 9);
                _cimg_mp_check_list();
              } else { p1 = ~0U; s0 = ss8; }
              if (s0==se1) compile(s0,se1,depth1,0,block_flags); // 'missing' argument error
              CImg<ulongT>::vector((ulongT)mp_ellipse,_cimg_mp_slot_nan,0,p1).move_to(l_opcode);
              for (s = s0; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                if (is_vector(arg2)) // Vector argument allowed to specify coordinates and color
                  CImg<ulongT>::sequence(size(arg2),arg2 + 1,arg2 + (ulongT)size(arg2)).move_to(l_opcode);
                else
                  CImg<ulongT>::vector(arg2).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              opcode[2] = opcode._height;
              opcode.move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"end(",4)) { // End
              _cimg_mp_op("Function 'end()'");
              s1 = ss4; while (s1<se1 && cimg::is_blank(*s1)) ++s1;
              if (s1!=se1) {
                if (!is_inside_end) code.swap(code_end);
                pos = compile(s1,se1,depth1,p_ref,8);
                if (!is_inside_end) code.swap(code_end);
                result_end_dim = size(pos);
                result_end = mem._data + pos;
                is_end_code = true;
              }
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"end_t(",6)) { // End thread
              _cimg_mp_op("Function 'end_t()'");
              s1 = ss6; while (s1<se1 && cimg::is_blank(*s1)) ++s1;
              if (s1!=se1) {
                if (!is_inside_end_t) code.swap(code_end_t);
                compile(s1,se1,depth1,p_ref,16);
                if (!is_inside_end_t) code.swap(code_end_t);
                is_end_code = true;
              }
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"epoch(",6)) { // Convert date to epoch
              _cimg_mp_op("Function 'epoch()'");
              is_sth = true; // Indicates that all arguments are constant
              CImg<ulongT> _op(1,8,1,1,(ulongT)~0U);
              arg1 = 2;
              if (ss6<se1)
                for (s = std::strchr(ss,'(') + 1; s<se; ++s) {
                  if (arg1>=_op._height) { arg1 = ~0U; break; }
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                  arg2 = compile(s,ns,depth1,0,block_flags);
                  if (is_vector(arg2)) {
                    p2 = size(arg2);
                    for (unsigned int k = 1; k<=p2; ++k) {
                      if (arg1>=_op._height) { arg1 = ~0U; break; }
                      _op[arg1++] = arg2 + k;
                    }
                  } else _op[arg1++] = arg2;
                  is_sth&=is_const_scalar(arg2);
                  s = ns;
                }
              else is_sth = false;
              if (arg1==~0U) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Too many arguments specified, in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s0);
              }

              _op.move_to(opcode);
              opcode[0] = (ulongT)mp_epoch;
              if (is_sth) _cimg_mp_const_scalar(mp_epoch(*this));
              pos = opcode[1] = scalar();
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"equalize(",9)) { // Equalize
              _cimg_mp_op("Function 'equalize()'");
              s0 = ss + 9;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = arg4 = ~0U;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              if (arg3!=~0U) _cimg_mp_check_type(arg3,3,1,0);
              if (arg4!=~0U) _cimg_mp_check_type(arg4,3,1,0);
              p1 = size(arg1);
              arg2 = (unsigned int)mem[arg2];
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_equalize,pos,arg1,p1,arg2,arg3,arg4).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

#if cimg_use_cpp11==1
            if (!std::strncmp(ss,"erf(",4)) { // Error function
              _cimg_mp_op("Function 'erf()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(erf,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::erf(mem[arg1]));
              _cimg_mp_scalar1(erf,arg1);
            }
#endif

            if (!std::strncmp(ss,"erfinv(",7)) { // Inverse of error function
              _cimg_mp_op("Function 'erfinv()'");
              arg1 = compile(ss7,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(erfinv,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::erfinv(mem[arg1]));
              _cimg_mp_scalar1(erfinv,arg1);
            }

            if (!std::strncmp(ss,"exp(",4)) { // Exponential
              _cimg_mp_op("Function 'exp()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(exp,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::exp(mem[arg1]));
              _cimg_mp_scalar1(exp,arg1);
            }

            if (!std::strncmp(ss,"expr(",5)) { // Vector from expression
              _cimg_mp_op("Function 'expr()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags); // formula
              _cimg_mp_check_type(arg1,1,2,0);
              p1 = size(arg1);
              arg2 = arg3 = arg4 = arg5 = 1; arg6 = ~0U;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags); // w
                _cimg_mp_check_const_scalar(arg2,2,3);
                arg2 = (unsigned int)mem[arg2];
                if (s2<se1) {
                  s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg3 = compile(s2,s1,depth1,0,block_flags); // h
                  _cimg_mp_check_const_scalar(arg3,3,3);
                  arg3 = (unsigned int)mem[arg3];
                  if (s1<se1) {
                    s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg4 = compile(s1,s2,depth1,0,block_flags); // d
                    _cimg_mp_check_const_scalar(arg4,4,3);
                    arg4 = (unsigned int)mem[arg4];
                    if (s2<se1) {
                      s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                      arg5 = compile(s2,s1,depth1,0,block_flags); // s
                      _cimg_mp_check_const_scalar(arg5,5,3);
                      arg5 = (unsigned int)mem[arg5];
                      arg6 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U; // A
                    }
                  }
                }
              }

              p2 = arg2*arg3*arg4; // whd
              p3 = p2*arg5; // whds

              unsigned int sizA = 0;
              if (arg6!=~0U) {
                _cimg_mp_check_type(arg6,6,2,0);
                sizA = size(arg6);
                if (sizA%p2) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Argument 'A' has an invalid size "
                                              "(%u, not a multiplier of %u*%u*%u = %u), "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              sizA,arg2,arg3,arg4,arg2*arg3*arg4,
                                              ss);
                }
              }
              if (p3) pos = vector(p3); else pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_expr,pos,arg1,p1,arg2,arg3,arg4,arg5,arg6,sizA/p2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"eye(",4)) { // Identity matrix
              _cimg_mp_op("Function 'eye()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              _cimg_mp_check_const_scalar(arg1,1,3);
              p1 = (unsigned int)mem[arg1];
              pos = vector(p1*p1);
              CImg<ulongT>::vector((ulongT)mp_eye,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'f' :
            if (!std::strncmp(ss,"f2ui(",5)) { // Special float->uint conversion
              _cimg_mp_op("Function 'f2ui()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(f2ui,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar((double)cimg::float2uint((T)mem[arg1]));
              _cimg_mp_scalar1(f2ui,arg1);
            }

            if (!std::strncmp(ss,"fact(",5)) { // Factorial
              _cimg_mp_op("Function 'fact()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(factorial,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::factorial((int)mem[arg1]));
              _cimg_mp_scalar1(factorial,arg1);
            }

            if (!std::strncmp(ss,"fibo(",5)) { // Fibonacci
              _cimg_mp_op("Function 'fibo()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(fibonacci,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::fibonacci((int)mem[arg1]));
              _cimg_mp_scalar1(fibonacci,arg1);
            }

            if (!std::strncmp(ss,"fill(",5)) { // Fill
              _cimg_mp_op("Function 'fill()'");
              s0 = ss5; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              arg1 = compile(ss5,s0,depth1,0,block_flags); // target
              _cimg_mp_check_type(arg1,1,2,0);
              s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              p1 = code._width;
              if (s1<se1) { // Version with >=3 arguments
                s2 = s1 + 1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                if (s2<se1) { // Version with 6 arguments: 'fill(target,w,h,d,s,'expr')'
                  arg2 = compile(s0,s1,depth1,0,block_flags); // w
                  arg3 = compile(++s1,s2,depth1,0,block_flags); // h
                  s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg4 = compile(s2,s1,depth1,0,block_flags); // d
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg5 = compile(s1,s2,depth1,0,block_flags); // s
                  arg6 = compile(++s2,se1,depth1,0,block_flags); // expr
                  _cimg_mp_check_const_scalar(arg2,2,3);
                  _cimg_mp_check_const_scalar(arg3,3,3);
                  _cimg_mp_check_const_scalar(arg4,4,3);
                  _cimg_mp_check_const_scalar(arg5,5,3);
                  _cimg_mp_check_type(arg6,6,2,0);
                  arg2 = (unsigned int)mem[arg2];
                  arg3 = (unsigned int)mem[arg3];
                  arg4 = (unsigned int)mem[arg4];
                  arg5 = (unsigned int)mem[arg5];
                  p1 = size(arg1);
                  if (p1!=arg2*arg3*arg4*arg5) {
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                                "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                p1,arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
                  }
                  CImg<ulongT>::vector((ulongT)mp_vector_fill_ext,arg1,arg2,arg3,arg4,arg5,arg6,size(arg6)).
                    move_to(code,p1);
                  _cimg_mp_return_nan();
                } else { // Version with 3 arguments: 'fill(target,index_name,expr)'
                  variable_name.assign(s0,(unsigned int)(s1 + 1 - s0)).back() = 0;
                  cimg::strpare(variable_name,false,true);
                  if (!cimg::is_varname(variable_name)) { // Invalid variable name
                    cimg::strellipsize(variable_name,64);
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Invalid loop variable name '%s', "
                                                "in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                variable_name._data,s0);
                  }
                  get_variable_pos(variable_name,arg2,arg3);
                  arg2 = arg3!=~0U?reserved_label[arg3]:arg2!=~0U?variable_pos[arg2]:~0U; // Variable slot
                  if (arg2!=~0U && (!is_scalar(arg2) ||
                                    is_const_scalar(arg2))) { // Variable is not a vector or is a constant->error
                    cimg::strellipsize(variable_name,64);
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Invalid type '%s' for variable '%s' "
                                                "(expected 'scalar'), in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                s_type(arg2)._data,variable_name._data,s0);
                  } else if (arg2==~0U) { // Variable does not exist -> create it
                    arg2 = scalar();
                    if (arg3!=~0U) reserved_label[arg3] = arg2;
                    else {
                      if (variable_def._width>=variable_pos._width) variable_pos.resize(-200,1,1,1,0);
                      variable_pos[variable_def._width] = arg2;
                      variable_name.move_to(variable_def);
                    }
                    memtype[arg2] = -1;
                  }
                  arg3 = compile(++s1,se1,depth1,0,block_flags);
                  _cimg_mp_check_type(arg3,3,1,0);
                }
              } else { // Version with 2 arguments : 'fill(target,expr)'
                arg2 = ~0U;
                arg3 = compile(s0,se1,depth1,0,block_flags);
              }
              // arg2 = variable slot, arg3 = fill expression.
              _cimg_mp_check_type(arg3,3,1,0);
              CImg<ulongT>::vector((ulongT)mp_vector_fill,arg1,size(arg1),arg2,arg3,code._width - p1).
                move_to(code,p1);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"find(",5)) { // Find
              _cimg_mp_op("Function 'find()'");

              // First argument: data to look at.
              s0 = ss5; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              if (*ss5=='#') { // Index specified
                p1 = compile(ss6,s0,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
                arg1 = ~0U;
              } else { // Vector specified
                arg1 = compile(ss5,s0,depth1,0,block_flags);
                if (!arg1) _cimg_mp_return(11); // Manage empty string -> -1
                _cimg_mp_check_type(arg1,1,2,0);
                p1 = ~0U;
              }

              // Second argument: data to find.
              s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg2 = compile(s0,s1,depth1,0,block_flags);

              // Third and fourth arguments: starting index and search direction.
              arg3 = _cimg_mp_slot_nan; arg4 = 1;
              if (s1<se1) {
                s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                arg3 = compile(s1,s0,depth1,0,block_flags);
                _cimg_mp_check_type(arg3,3,1,0);
                if (s0<se1) {
                  arg4 = compile(++s0,se1,depth1,0,block_flags);
                  _cimg_mp_check_type(arg4,4,1,0);
                }
              }
              if (p1!=~0U) {
                if (size(arg2)>1)
                  _cimg_mp_scalar5(image_find_seq,p1,arg2,size(arg2),arg3,arg4);
                _cimg_mp_scalar4(image_find,p1,arg2 + (size(arg2)?1:0),arg3,arg4);
              }
              if (size(arg2)>1)
                _cimg_mp_scalar6(find_seq,arg1,size(arg1),arg2,size(arg2),arg3,arg4);
              _cimg_mp_scalar5(find,arg1,size(arg1),arg2 + (size(arg2)?1:0),arg3,arg4);
            }

            if (*ss1=='o' && *ss2=='r' && *ss3=='(') { // For loop
              _cimg_mp_op("Function 'for()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              s2 = s1 + 1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              s3 = s2 + 1; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
              arg1 = code._width;
              p1 = compile(ss4,s1,depth1,0,block_flags); // Init
              arg2 = code._width;
              p2 = compile(++s1,s2,depth1,0,block_flags); // Cond
              arg3 = code._width;
              arg6 = mempos;
              if (s3<se1) { // Body + post
                p3 = compile(s3 + 1,se1,depth1,0,block_flags); // Body
                arg4 = code._width;
                pos = compile(++s2,s3,depth1,0,block_flags); // Post
              } else {
                p3 = compile(++s2,se1,depth1,0,block_flags); // Body only
                arg4 = pos = code._width;
              }
              _cimg_mp_check_type(p2,2,1,0);
              arg5 = size(pos);
              CImg<ulongT>::vector((ulongT)mp_for,p3,(ulongT)size(p3),p2,arg2 - arg1,arg3 - arg2,
                                   arg4 - arg3,code._width - arg4,
                                   p3>=arg6 && !is_const_scalar(p3),
                                   p2>=arg6 && !is_const_scalar(p2)).move_to(code,arg1);
              _cimg_mp_return(p3);
            }

            if (!std::strncmp(ss,"flood(",6)) { // Flood fill image
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'flood()'");
              if (*ss6=='#') { // Index specified
                s0 = ss7; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss7,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss7);
                _cimg_mp_check_list();
              } else { p1 = ~0U; s0 = ss6; }
              CImg<ulongT>::vector((ulongT)mp_flood,_cimg_mp_slot_nan,0,p1).move_to(l_opcode);
              for (s = s0; s<se1; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                if (is_vector(arg2)) // Vector argument allowed to specify coordinates and color
                  CImg<ulongT>::sequence(size(arg2),arg2 + 1,arg2 + (ulongT)size(arg2)).move_to(l_opcode);
                else
                  CImg<ulongT>::vector(arg2).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              opcode[2] = opcode._height;
              opcode.move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"floor(",6)) { // Floor
              _cimg_mp_op("Function 'floor()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(floor,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::floor(mem[arg1]));
              _cimg_mp_scalar1(floor,arg1);
            }

            if (!std::strncmp(ss,"frac(",5)) { // Fractional part
              _cimg_mp_op("Function 'frac()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(frac,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::frac(mem[arg1]));
              _cimg_mp_scalar1(frac,arg1);
            }

            if (!std::strncmp(ss,"fsize(",6)) { // File size
              _cimg_mp_op("Function 'fsize()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_fsize,pos,arg1,(ulongT)size(arg1)).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'g' :
#if cimg_use_cpp11==1
            if (!std::strncmp(ss,"gamma(",6)) { // Gamma
              _cimg_mp_op("Function 'gamma()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(gamma,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::tgamma(mem[arg1]));
              _cimg_mp_scalar1(gamma,arg1);
            }
#endif

            if (!std::strncmp(ss,"gauss(",6)) { // Gaussian function
              _cimg_mp_op("Function 'gauss()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              arg2 = arg3 = 1;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1;
              }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              if (is_vector(arg1)) _cimg_mp_vector3(gauss,arg1,arg2,arg3);
              if (is_const_scalar(arg1) && is_const_scalar(arg2) && is_const_scalar(arg3)) {
                val1 = mem[arg1];
                val2 = mem[arg2];
                _cimg_mp_const_scalar(std::exp(-val1*val1/(2*val2*val2))/(mem[arg3]?std::sqrt(2*val2*val2*cimg::PI):1));
              }
              _cimg_mp_scalar3(gauss,arg1,arg2,arg3);
            }

#ifdef cimg_mp_func_get
            if (!std::strncmp(ss,"get(",4)) { // Get value from external variable
              _cimg_mp_op("Function 'get()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = arg3 = 0;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,2);
              _cimg_mp_check_type(arg3,3,1,0);
              p1 = size(arg1);

              const int siz_max = cimg::type<int>::max();
              if (mem[arg2]>=siz_max) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Specified variable size %g is larger than %d.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            mem[arg2],siz_max);
              }
              arg2 = (unsigned int)mem[arg2];
              if (arg2) pos = vector(arg2); else pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_get,pos,arg1,p1,arg2,arg3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
#endif
            break;

          case 'h' :
            if (*ss1=='(') { // Image height
              _cimg_mp_op("Function 'h()'");
              if (*ss2=='#') { // Index specified
                p1 = compile(ss3,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss3);
                _cimg_mp_check_list();
              } else { if (ss2!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_height,p1);
            }

            if (!std::strncmp(ss,"histogram(",10)) { // Compute histogram
              _cimg_mp_op("Function 'histogram()'");
              s0 = ss + 10;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = arg4 = ~0U;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              if (arg3!=~0U) _cimg_mp_check_type(arg3,3,1,0);
              if (arg4!=~0U) _cimg_mp_check_type(arg4,3,1,0);
              p1 = size(arg1);
              arg2 = (unsigned int)mem[arg2];
              pos = vector(arg2);
              CImg<ulongT>::vector((ulongT)mp_histogram,pos,arg1,p1,arg2,arg3,arg4).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'i' :
            if (*ss1=='a' && *ss2=='(') { // Image average
              _cimg_mp_op("Function 'ia()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_ia,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='c' && *ss2=='(') { // Image median
              _cimg_mp_op("Function 'ic()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_ic,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='d' && *ss2=='(') { // Image std
              _cimg_mp_op("Function 'id()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_id,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='f' && *ss2=='(') { // If..then[..else.]
              _cimg_mp_op("Function 'if()'");
              s1 = ss3; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              s2 = s1 + 1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg1 = compile(ss3,s1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,1,0);
              if (is_const_scalar(arg1)) {
                if ((bool)mem[arg1]) return compile(++s1,s2,depth1,0,block_flags);
                else return s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              }
              p2 = code._width;
              arg2 = compile(++s1,s2,depth1,0,block_flags);
              p3 = code._width;
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):
                is_vector(arg2)?vector(size(arg2),0):0;
              _cimg_mp_check_type(arg3,3,is_vector(arg2)?2:1,size(arg2));
              arg4 = size(arg2);
              if (arg4) pos = vector(arg4); else pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_if,pos,arg1,arg2,arg3,
                                   p3 - p2,code._width - p3,arg4).move_to(code,p2);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='m' && *ss2=='(') { // Image minimum value
              _cimg_mp_op("Function 'im()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_im,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='M' && *ss2=='(') { // Image maximum value
              _cimg_mp_op("Function 'iM()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_iM,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='n' && *ss2=='(') { // Image norm
              _cimg_mp_op("Function 'in()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_in,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='p' && *ss2=='(') { // Image product
              _cimg_mp_op("Function 'ip()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_ip,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='s' && *ss2=='(') { // Image sum
              _cimg_mp_op("Function 'is()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_is,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='v' && *ss2=='(') { // Image variance
              _cimg_mp_op("Function 'iv()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_iv,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"index(",6)) { // Index colors
              _cimg_mp_op("Function 'index()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags);
              arg4 = arg5 = 0;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg4 = compile(s1,s2,depth1,0,block_flags);
                arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_type(arg2,2,2,0);
              _cimg_mp_check_const_scalar(arg3,3,3);
              _cimg_mp_check_type(arg4,4,1,0);
              _cimg_mp_check_const_scalar(arg5,5,2);
              p1 = size(arg1);
              p2 = size(arg2);
              arg3 = (unsigned int)mem[arg3];
              arg5 = (unsigned int)mem[arg5];
              p3 = p2/arg3; // Number of color entries
              if (p2!=p3*arg3) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Colormap size (%u values) and specified "
                                            "dimension of colormap entries (%u) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p2,1U),arg3);
              }
              if (p1%arg3) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Input vector size (%u values) and specified "
                                            "dimension of colormap entries (%u) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p1,1U),arg3);
              }
              pos = vector(arg5?p1:p1/arg3);
              CImg<ulongT>::vector((ulongT)mp_index,pos,arg1,p1,arg2,p2,arg3,arg4,arg5).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"indexof(",8)) { // Index of element in list of elements
              _cimg_mp_op("Function 'indexof()'");
              s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss8,s1,depth1,0,block_flags); // elt
              is_sth = is_const_scalar(arg1); // All elements are constant scalars ?
              if (is_sth) val = mem[arg1];
              p1 = 0;
              CImg<ulongT>::vector((ulongT)mp_indexof,0,0,arg1,size(arg1)).move_to(l_opcode);
              for (s = ++s1; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                is_sth&=is_const_scalar(arg2);
                if (is_sth && mem[arg2]==val) _cimg_mp_const_scalar((double)p1);
                CImg<ulongT>::vector(arg2,size(arg2)).move_to(l_opcode);
                s = ns;
                ++p1;
              }
              if (is_sth) _cimg_mp_return(11); // Const case: no match
              (l_opcode>'y').move_to(opcode);
              opcode[1] = pos = scalar();
              opcode[2] = opcode._height;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"inrange(",8)) { // Check value range
              _cimg_mp_op("Function 'inrange()'");
              s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss8,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags);
              arg4 = arg5 = 1;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg4 = compile(s1,s2,depth1,0,block_flags);
                arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):arg4;
                _cimg_mp_check_type(arg4,4,1,0);
                _cimg_mp_check_type(arg5,5,1,0);
              }
              if (is_const_scalar(arg1) && is_const_scalar(arg2) &&
                  is_const_scalar(arg3) && is_const_scalar(arg4) &&
                  is_const_scalar(arg5)) { // Optimize constant case
                val = mem[arg1]; val1 = mem[arg2]; val2 = mem[arg3];
                if (val2>=val1)
                  is_sth = (mem[arg4]?(val>=val1):(val>val1)) && (mem[arg5]?(val<=val2):(val<val2));
                else
                  is_sth = (mem[arg5]?(val>=val2):(val>val2)) && (mem[arg4]?(val<=val1):(val<val1));
                _cimg_mp_return(is_sth?1:0);
              }
              p1 = size(arg1);
              p2 = size(arg2);
              p3 = size(arg3);
              arg6 = ~0U; // Size of return value
              if (!p1) {
                arg6 = p2?p2:p3;
                if (arg6) _cimg_mp_check_type(arg3,3,3,arg6);
              } else {
                arg6 = p1;
                _cimg_mp_check_type(arg2,2,3,arg6);
                _cimg_mp_check_type(arg3,3,3,arg6);
              }
              pos = arg6?vector(arg6):scalar();
              CImg<ulongT>::vector((ulongT)mp_inrange,pos,arg6,arg1,p1,arg2,p2,arg3,p3,arg4,arg5).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"int(",4)) { // Integer cast
              _cimg_mp_op("Function 'int()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(int,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar((longT)mem[arg1]);
              _cimg_mp_scalar1(int,arg1);
            }

            if (!std::strncmp(ss,"invert(",7)) { // Matrix/scalar inverse (or pseudoinverse)
              _cimg_mp_op("Function 'invert()'");
              s1 = ss7; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss7,s1,depth1,0,block_flags); // A
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U; // nb_colsA
              if (arg2!=~0U) {
                _cimg_mp_check_const_scalar(arg2,2,3);
                arg2 = (unsigned int)mem[arg2];
              }
              if (is_vector(arg1)) {
                p1 = size(arg1);
                if (arg2==~0U) { // nb_colsA not specified: assuming square matrix
                  _cimg_mp_check_matrix_square(arg1,1);
                  p2 = p3 = (unsigned int)cimg::round(std::sqrt((float)p1));
                } else {
                  p2 = arg2;
                  p3 = p1/p2;
                  if (p3*p2!=p1) {
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Type of first argument ('%s') "
                                                "does not match with second argument 'nb_colsA=%u', "
                                                "in expression '%s'.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                s_type(arg1)._data,p2,s0);
                  }
                }
                pos = vector(p1);
                CImg<ulongT>::vector((ulongT)mp_matrix_invert,pos,arg1,p2,p3).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(1/mem[arg1]);
              _cimg_mp_scalar2(div,1,arg1);
            }

            if (*ss1=='s') { // Family of 'is_?()' functions

              if (!std::strncmp(ss,"isbool(",7)) { // Is boolean?
                _cimg_mp_op("Function 'isbool()'");
                if (ss7==se1) _cimg_mp_return(0);
                try { arg1 = compile(ss7,se1,depth1,0,block_flags); }
                catch (CImgException&) { _cimg_mp_return(0); }
                if (is_vector(arg1)) _cimg_mp_vector1(isbool,arg1);
                if (is_const_scalar(arg1)) _cimg_mp_return(mem[arg1]==0. || mem[arg1]==1.);
                _cimg_mp_scalar1(isbool,arg1);
              }

              if (!std::strncmp(ss,"isconst(",8)) { // Is constant?
                _cimg_mp_op("Function 'isconst()'");
                if (ss8==se1) _cimg_mp_return(0);
                try { arg1 = compile(ss8,se1,depth1,0,block_flags); }
                catch (CImgException&) { _cimg_mp_return(0); }
                if (is_const_scalar(arg1)) _cimg_mp_return(1);
                _cimg_mp_return(0);
              }

              if (!std::strncmp(ss,"isdir(",6)) { // Is directory?
                _cimg_mp_op("Function 'isdir()'");
                arg1 = compile(ss6,se1,depth1,0,block_flags);
                pos = scalar();
                CImg<ulongT>::vector((ulongT)mp_isdir,pos,arg1,(ulongT)size(arg1)).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }

              if (!std::strncmp(ss,"isexpr(",7)) { // Is valid expression?
                _cimg_mp_op("Function 'isexpr()'");
                if (ss7==se1) _cimg_mp_return(0);
                try { arg1 = compile(ss7,se1,depth1,0,block_flags); }
                catch (CImgException&) { _cimg_mp_return(0); }
                _cimg_mp_return(1);
              }

              if (!std::strncmp(ss,"isfile(",7)) { // Is file?
                _cimg_mp_op("Function 'isfile()'");
                arg1 = compile(ss7,se1,depth1,0,block_flags);
                pos = scalar();
                CImg<ulongT>::vector((ulongT)mp_isfile,pos,arg1,(ulongT)size(arg1)).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }

              if (!std::strncmp(ss,"isfinite(",9)) { // Is finite?
                _cimg_mp_op("Function 'isfinite()'");
                s0 = ss + 9;
                if (s0==se1) _cimg_mp_return(0);
                arg1 = compile(s0,se1,depth1,0,block_flags);
                if (is_vector(arg1)) _cimg_mp_vector1(isfinite,arg1);
                if (is_const_scalar(arg1))
                  _cimg_mp_return((unsigned int)cimg::type<double>::is_finite(mem[arg1]));
                _cimg_mp_scalar1(isfinite,arg1);
              }

              if (!std::strncmp(ss,"isin(",5)) { // Is in sequence/vector?
                if (ss5>=se1) _cimg_mp_return(0);
                _cimg_mp_op("Function 'isin()'");
                is_sth = true; // Are all arguments constants ?
                for (s = ss5; s<se; ++s) {
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                  arg1 = compile(s,ns,depth1,0,block_flags);
                  if (!is_const_scalar(arg1)) is_sth = false;
                  CImg<ulongT>::vector(arg1,size(arg1)).move_to(l_opcode);
                  s = ns;
                }
                if (is_sth) { // All arguments are constant -> return constant
                  if (l_opcode._width<2) _cimg_mp_return(0);
                  const double target = mem[l_opcode(0,0)];
                  for (unsigned int i = 1; i<l_opcode._width; ++i) {
                    if (mem[l_opcode(i,0)]==target) _cimg_mp_return(1);
                  }
                  _cimg_mp_return(0);
                }
                pos = scalar();
                CImg<ulongT>::vector((ulongT)mp_isin,pos,0).move_to(l_opcode,0);
                (l_opcode>'y').move_to(opcode);
                opcode[2] = opcode._height;
                opcode.move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }

              if (!std::strncmp(ss,"isinf(",6)) { // Is infinite?
                _cimg_mp_op("Function 'isinf()'");
                if (ss6==se1) _cimg_mp_return(0);
                arg1 = compile(ss6,se1,depth1,0,block_flags);
                if (is_vector(arg1)) _cimg_mp_vector1(isinf,arg1);
                if (is_const_scalar(arg1))
                  _cimg_mp_return((unsigned int)cimg::type<double>::is_inf(mem[arg1]));
                _cimg_mp_scalar1(isinf,arg1);
              }

              if (!std::strncmp(ss,"isint(",6)) { // Is integer?
                _cimg_mp_op("Function 'isint()'");
                if (ss6==se1) _cimg_mp_return(0);
                s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                try { arg1 = compile(ss6,s1,depth1,0,block_flags); }
                catch (CImgException&) { _cimg_mp_return(0); }
                arg2 = arg3 = ~0U;
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg2 = compile(s1,s2,depth1,0,block_flags);
                  arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):~0U;
                }
                if (arg2!=~0U) _cimg_mp_check_type(arg2,2,1,0);
                if (arg3!=~0U) _cimg_mp_check_type(arg3,3,1,0);
                if (is_vector(arg1)) _cimg_mp_vector3(isint,arg1,arg2,arg3);
                if (is_const_scalar(arg1) && (arg2==~0U || is_const_scalar(arg2)) &&
                    (arg3==~0U || is_const_scalar(arg3))) {
                  val = mem[arg1];
                  is_sth = std::modf(val,&val1)==0;
                  if (arg2==~0U) _cimg_mp_return(is_sth);
                  if (arg3==~0U) _cimg_mp_return(is_sth && val>=mem[arg2]);
                  _cimg_mp_return(is_sth && val>=mem[arg2] && val<=mem[arg3]);
                }
                _cimg_mp_scalar3(isint,arg1,arg2,arg3);
              }

              if (!std::strncmp(ss,"isnan(",6)) { // Is NaN?
                _cimg_mp_op("Function 'isnan()'");
                if (ss6==se1) _cimg_mp_return(0);
                arg1 = compile(ss6,se1,depth1,0,block_flags);
                if (is_vector(arg1)) _cimg_mp_vector1(isnan,arg1);
                if (is_const_scalar(arg1))
                  _cimg_mp_return((unsigned int)cimg::type<double>::is_nan(mem[arg1]));
                _cimg_mp_scalar1(isnan,arg1);
              }

              if (!std::strncmp(ss,"isnum(",6)) { // Is number?
                _cimg_mp_op("Function 'isnum()'");
                val = 0;
                if (cimg_sscanf(ss6,"%lf%c%c",&val,&sep,&end)==2 && sep==')') _cimg_mp_return(1);
                _cimg_mp_return(0);
              }

              if (!std::strncmp(ss,"ispercentage(",13)) { // Does argument ends with '%'?
                _cimg_mp_op("Function 'ispercentage()'");
                _cimg_mp_return((unsigned int)(*se2=='%'));
              }

              if (!std::strncmp(ss,"isvar(",6)) { // Is existing variable?
                _cimg_mp_op("Function 'isvar()'");
                if (ss6==se1) _cimg_mp_return(0);
                s1 = ss6; while (s1<se && (*s1!=')' || level[s1 - expr._data]!=clevel)) ++s1; // Closing parenthesis
                if (*s1!=')') _cimg_mp_return(0);
                variable_name.assign(s1 - ss6 + 1);
                if (variable_name._width) std::memcpy(variable_name,ss6,variable_name.width() - 1);
                variable_name.back() = 0;
                get_variable_pos(variable_name,arg1,arg2);
                if (arg1!=~0U || arg2!=~0U) _cimg_mp_return(1);
                _cimg_mp_return(0);
              }

              if (!std::strncmp(ss,"isvarname(",10)) { // Is variable name?
                _cimg_mp_op("Function 'isvarname()'");
                arg1 = compile(ss + 10,se1,depth1,0,block_flags);
                pos = scalar();
                CImg<ulongT>::vector((ulongT)mp_isvarname,pos,arg1,(ulongT)size(arg1)).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }
            }
            break;

          case 'l' :
            if (*ss1=='(') { // Size of image list
              _cimg_mp_op("Function 'l()'");
              if (ss2!=se1) break;
              _cimg_mp_scalar0(size_list);
            }

            if (!std::strncmp(ss,"lerp(",5)) { // Linear interpolation
              _cimg_mp_op("Function 'lerp()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = compile(++s2,se1,depth1,0,block_flags);
              if (is_vector(arg1)) p1 = size(arg1);
              else if (is_vector(arg2)) p1 = size(arg2);
              else p1 = size(arg3);
              _cimg_mp_check_type(arg1,1,3,p1);
              _cimg_mp_check_type(arg2,2,3,p1);
              _cimg_mp_check_type(arg3,3,3,p1);
              if (is_const_scalar(arg3)) { // Optimize constant cases
                if (!arg3) _cimg_mp_same(arg1);
                if (arg3==1) _cimg_mp_same(arg2);
                if (is_const_scalar(arg1) && is_const_scalar(arg2)) {
                  const double t = mem[arg3];
                  _cimg_mp_const_scalar(mem[arg1]*(1 - t) + mem[arg2]*t);
                }
              }
              if (!p1) _cimg_mp_scalar3(lerp,arg1,arg2,arg3);
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_vector_lerp,pos,p1,arg1,size(arg1),arg2,size(arg2),arg3,size(arg3)).
                move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"log(",4)) { // Natural logarithm
              _cimg_mp_op("Function 'log()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(log,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::log(mem[arg1]));
              _cimg_mp_scalar1(log,arg1);
            }

            if (!std::strncmp(ss,"log10(",6)) { // Base-10 logarithm
              _cimg_mp_op("Function 'log10()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(log10,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::log10(mem[arg1]));
              _cimg_mp_scalar1(log10,arg1);
            }

            if (!std::strncmp(ss,"log2(",5)) { // Base-2 logarithm
              _cimg_mp_op("Function 'log2()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(log2,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::log2(mem[arg1]));
              _cimg_mp_scalar1(log2,arg1);
            }

            if (!std::strncmp(ss,"logit(",6)) { // Logit
              _cimg_mp_op("Function 'logit()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(logit,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::logit(mem[arg1]));
              _cimg_mp_scalar1(logit,arg1);
            }

            if (!std::strncmp(ss,"lowercase(",10)) { // Lower case
              _cimg_mp_op("Function 'lowercase()'");
              arg1 = compile(ss + 10,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(lowercase,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::lowercase(mem[arg1]));
              _cimg_mp_scalar1(lowercase,arg1);
            }
            break;

          case 'm' :
            if (!std::strncmp(ss,"map(",4)) { // Map vector
              _cimg_mp_op("Function 'map()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags); // X
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags); // P
              arg3 = arg4 = 1; arg5 = 0;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags); // nb_channelsX
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg4 = compile(s1,s2,depth1,0,block_flags); // nb_channelsP
                  arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0; // boundary_conditions
                }
              }
              _cimg_mp_check_type(arg2,2,2,0);
              _cimg_mp_check_const_scalar(arg3,3,3);
              _cimg_mp_check_const_scalar(arg4,4,3);
              _cimg_mp_check_type(arg5,5,1,0);
              p1 = size(arg1);
              p2 = size(arg2);
              arg3 = (unsigned int)mem[arg3];
              arg4 = (unsigned int)mem[arg4];
              if ((p1%arg3) || (!p1 && arg3!=1)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of first arguments ('%s') "
                                            "does not match with third argument 'nb_channelsX=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,arg3,s0);
              }
              if (p2%arg4) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of second arguments ('%s') "
                                            "does not match with fourth argument 'nb_channelsP=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg2)._data,arg4,s0);
              }
              if (!p1 && arg4==1) pos = scalar();
              else pos = vector(std::max(p1,1U)*arg4);
              CImg<ulongT>::vector((ulongT)mp_map,pos,arg1,p1,arg2,p2,arg3,arg4,arg5).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"merge(",6)) { // Merge inter-thread variables
              _cimg_mp_op("Function 'merge()'");
              if (!is_inside_end) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Function should be called in an 'end()' block, "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s0);
              }
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              ref.assign(7);
              pos = compile(ss6,s1,depth1,ref,block_flags);
              if (*ref) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: First argument cannot be a linked reference, "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s0);
              }
              arg1 = ~0U; // Merge operator
                          // (0='=',1='+',2='-',3='*',4='/',5='&',6='|',7='xor',8='&&',9=='||',10='min',11='max')
              if (s1<se1) {
                ++s1;
                char st_op[4] = {};
                is_sth = false; // blank after operator?
                if (cimg_sscanf(s1," %3[=-+/*&|minaxor]%c",st_op,&sep)==2 && (sep==')' ||
                                                                              (is_sth=cimg::is_blank(sep)))) {
                  if (!is_sth || (is_sth && cimg_sscanf(s1," %*[=+-*&/|minaxor ]%c",&sep)==1 && sep==')')) {
                    cimg::strpare(st_op,' ',false,true);
                    if (!st_op[1])
                      arg1 = *st_op=='='?0:*st_op=='+'?1:*st_op=='-'?2:*st_op=='*'?3:*st_op=='/'?4:
                        *st_op=='&'?5:*st_op=='|'?6:~0U;
                    else if (*st_op=='x' && st_op[1]=='o' && st_op[2]=='r' && !st_op[3]) arg1 = 7;
                    else if (*st_op=='&' && st_op[1]=='&' && !st_op[2]) arg1 = 8;
                    else if (*st_op=='|' && st_op[1]=='|' && !st_op[2]) arg1 = 9;
                    else if (*st_op=='m' && st_op[1]=='i' && st_op[2]=='n' && !st_op[3]) arg1 = 10;
                    else if (*st_op=='m' && st_op[1]=='a' && st_op[2]=='x' && !st_op[3]) arg1 = 11;
                  }
                }
              }
              cimg_rofY(memmerge,k) if (memmerge(0,k)==(int)pos) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Merge has already been requested before "
                                            "for specified variable "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,s0);
              }
              if (arg1==~0U) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Invalid specified operator "
                                            "(should be one of '=,+,-,*,/,&,|,xor,&&,||,min,max'), "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,s0);
              }
              memmerge.resize(3,memmerge._height + 1,1,1,0,0);
              memmerge(0,memmerge._height - 1) = (int)pos;
              memmerge(1,memmerge._height - 1) = (int)size(pos);
              memmerge(2,memmerge._height - 1) = (int)arg1;
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"mirror(",7)) { // Mirror image
              _cimg_mp_op("Function 'mirror()'");
              s1 = ss7; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss7,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg4 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg5 = compile(s2,s1,depth1,0,block_flags);
              arg6 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              _cimg_mp_check_const_scalar(arg3,3,3);
              _cimg_mp_check_const_scalar(arg4,4,3);
              _cimg_mp_check_const_scalar(arg5,5,3);
              p1 = size(arg1);
              p2 = size(arg6);
              arg2 = (unsigned int)mem[arg2];
              arg3 = (unsigned int)mem[arg3];
              arg4 = (unsigned int)mem[arg4];
              arg5 = (unsigned int)mem[arg5];
              if (arg2*arg3*arg4*arg5!=std::max(1U,p1)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                            "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p1,1U),arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
              }
              pos = vector(arg2*arg3*arg4*arg5);
              CImg<ulongT>::vector((ulongT)mp_mirror,pos,arg1,arg2,arg3,arg4,arg5,arg6,p2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"mproj(",6)) { // Project matrix onto dictionary
              _cimg_mp_op("Function 'mproj()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags); // S
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags); // ncolS
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags); // D
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg4 = compile(s1,s2,depth1,0,block_flags); // ncolD
              arg5 = arg6 = p3 = 0;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg5 = compile(s2,s1,depth1,0,block_flags); // method
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg6 = compile(s1,s2,depth1,0,block_flags); // max_iter
                  p3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0; // method
                }
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              _cimg_mp_check_type(arg3,3,2,0);
              _cimg_mp_check_const_scalar(arg4,4,3);
              _cimg_mp_check_type(arg5,5,1,0);
              _cimg_mp_check_type(arg6,6,1,0);
              _cimg_mp_check_type(p3,7,1,0);
              p1 = size(arg1);
              p2 = size(arg3);
              const unsigned int
                wS = (unsigned int)mem[arg2],
                wD = (unsigned int)mem[arg4],
                hS = p1/wS,
                hD = p2/wD;

              if (wS*hS!=p1) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of first argument ('%s') "
                                            "does not match the second argument 'nb_colsS=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,wS,s0);
              }
              if (wD*hD!=p2) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of third argument ('%s') "
                                            "does not match the fourth argument 'nb_colsD=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg3)._data,wD,s0);
              }
              if (hS!=hD) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of first argument ('%s') "
                                            "does not match the third argument ('%s'), "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,s_type(arg3)._data,s0);
              }
              pos = vector(wS*wD);
              CImg<ulongT>::vector((ulongT)mp_mproj,pos,arg1,wS,hS,arg3,wD,arg5,arg6,p3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"mse(",4)) { // Mean-squared error
              _cimg_mp_op("Function 'mse()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg2,2,is_scalar(arg1)?1:2,size(arg1));
              _cimg_mp_scalar3(mse,arg1,arg2,size(arg1));
            }

            if (!std::strncmp(ss,"mul(",4)) { // Matrix multiplication
              _cimg_mp_op("Function 'mul()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_type(arg2,2,2,0);
              _cimg_mp_check_const_scalar(arg3,3,3);
              p1 = size(arg1);
              p2 = size(arg2);
              p3 = (unsigned int)mem[arg3];
              arg5 = p2/p3;
              if (!arg5 || (arg4 = p1/arg5)*arg5!=p1 || arg5*p3!=p2) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Types of first and second arguments ('%s' and '%s') "
                                            "do not match the third argument 'nb_colsB=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,s_type(arg2)._data,p3,s0);
              }
              pos = vector(arg4*p3);
              CImg<ulongT>::vector((ulongT)mp_matrix_mul,pos,arg1,arg2,arg4,arg5,p3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'n' :
#ifdef cimg_mp_func_name
            if (!std::strncmp(ss,"name(",5)) { // Get image name as a string vector
              _cimg_mp_op("Function 'name()'");
              if (*ss5=='#') { // Index specified
                s0 = ss6; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss6,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
                is_sth = true; // is_index_specified?
              } else { s0 = ss5; p1 = get_mem_img_index(); is_sth = false; }
              arg1 = s0<se1?compile(s0,se1,depth1,0,block_flags):~0U;
              if (arg1!=~0U) {
                _cimg_mp_check_const_scalar(arg1,is_sth?2:1,3);
                arg1 = (unsigned int)mem[arg1];
              } else arg1 = 1024;
              pos = vector(arg1);
              CImg<ulongT>::vector((ulongT)mp_name,pos,p1,arg1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
#endif

            if (!std::strncmp(ss,"narg(",5)) { // Number of arguments
              _cimg_mp_op("Function 'narg()'");
              if (ss5>=se1) _cimg_mp_return(0);
              arg1 = 0;
              for (s = ss5; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                ++arg1; s = ns;
              }
              _cimg_mp_const_scalar((double)arg1);
            }

            if (!std::strncmp(ss,"noise(",6)) { // Add noise
              _cimg_mp_op("Function 'noise()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              p1 = size(arg1);
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_noise,pos,arg1,p1,arg2,arg3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"normalize(",10)) { // Normalize
              _cimg_mp_op("Function 'normalize()'");
              s0 = ss + 10;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);

              arg2 = arg4 = 0; arg3 = 1;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg3 = compile(s1,s2,depth1,0,block_flags);
                if (s2<se1) {
                  s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg2 = arg3;
                  arg3 = compile(s2,s1,depth1,0,block_flags);
                  arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):0;
                }
              }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              _cimg_mp_check_type(arg4,4,1,0);
              if (is_scalar(arg1)) _cimg_mp_scalar3(lerp,arg2,arg3,arg4);
              p1 = size(arg1);
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_normalize,pos,arg1,p1,arg2,arg3,arg4).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"normp(",6)) { // Lp norm, with variable argument p
              _cimg_mp_op("Function 'normp()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):2;
              _cimg_mp_check_type(arg2,0,1,0);
              p1 = size(arg1);
              _cimg_mp_scalar3(normp,arg1,p1,arg2);
            }
            break;

          case 'o' :
            if (!std::strncmp(ss,"o2c(",4)) { // Offset to coordinates
              _cimg_mp_op("Function 'o2c()'");
              if (*ss4=='#') { // Index specified
                s0 = ss5; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss5,s0++,depth1,0,block_flags);
                p2 = 1;
                _cimg_mp_check_notnan_index(p1,ss5);
                _cimg_mp_check_list();
              } else { p1 = ~0U; s0 = ss4; p2 = 0; }
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              arg2 = s1!=se1?compile(++s1,se1,depth1,0,block_flags):0;
              _cimg_mp_check_type(arg1,p2 + 1,1,0);
              _cimg_mp_check_type(arg2,p2 + 2,1,0);
              pos = vector(4);
              CImg<ulongT>::vector((ulongT)mp_o2c,pos,p1,arg1,arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'p' :
            if (!std::strncmp(ss,"perm(",5)) { // Number of permutations
              _cimg_mp_op("Function 'perm()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              _cimg_mp_check_type(arg1,1,1,0);
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              if (is_const_scalar(arg1) && is_const_scalar(arg2) && is_const_scalar(arg3))
                _cimg_mp_const_scalar(cimg::permutations((int)mem[arg1],(int)mem[arg2],(bool)mem[arg3]));
              _cimg_mp_scalar3(permutations,arg1,arg2,arg3);
            }

            if (!std::strncmp(ss,"permute(",8)) { // Permute axes
              _cimg_mp_op("Function 'permute()'");
              s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss8,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg4 = compile(s1,s2,depth1,0,block_flags);
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg5 = compile(s2,s1,depth1,0,block_flags);
              arg6 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              _cimg_mp_check_const_scalar(arg3,3,3);
              _cimg_mp_check_const_scalar(arg4,4,3);
              _cimg_mp_check_const_scalar(arg5,5,3);
              _cimg_mp_check_type(arg6,6,2,0);
              p1 = size(arg1);
              p2 = size(arg6);
              arg2 = (unsigned int)mem[arg2];
              arg3 = (unsigned int)mem[arg3];
              arg4 = (unsigned int)mem[arg4];
              arg5 = (unsigned int)mem[arg5];
              if (arg2*arg3*arg4*arg5!=std::max(1U,p1)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                            "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p1,1U),arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
              }
              pos = vector(arg2*arg3*arg4*arg5);
              CImg<ulongT>::vector((ulongT)mp_permute,pos,arg1,arg2,arg3,arg4,arg5,arg6,p2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"polygon(",8)) { // Polygon/line drawing
              if (!is_inside_critical) is_parallelizable = false;
              _cimg_mp_op("Function 'polygon()'");
              if (*ss8=='#') { // Index specified
                s0 = ss + 9; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss + 9,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss + 9);
                _cimg_mp_check_list();
                pos = 2;
              } else { p1 = ~0U; s0 = ss8; pos = 1; }
              if (s0==se1) compile(s0,se1,depth1,0,block_flags); // 'missing' argument error
              CImg<ulongT>::vector((ulongT)mp_polygon,_cimg_mp_slot_nan,0,p1).move_to(l_opcode);
              for (s = s0; s<se; ++s, ++pos) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                if (pos>1 && is_vector(arg2)) // Vector argument allowed to specify coordinates and color
                  CImg<ulongT>::sequence(size(arg2),arg2 + 1,arg2 + (ulongT)size(arg2)).move_to(l_opcode);
                else {
                  _cimg_mp_check_type(arg2,pos,1,0);
                  CImg<ulongT>::vector(arg2).move_to(l_opcode);
                }
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              opcode[2] = opcode._height;
              opcode.move_to(code);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"print(",6) ||
                !std::strncmp(ss,"prints(",7)) { // Print expressions
              s0 = ss6 + (*ss5=='('?0:1);
              is_sth = *ss5=='s'; // corresponding string must be printed?
              _cimg_mp_op(is_sth?"Function 'prints()'":"Function 'print()'");
              if (!is_sth && *s0=='#') { // Image
                p1 = compile(ss7,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss7);
                _cimg_mp_check_list();
                CImg<ulongT>::vector((ulongT)mp_image_print,_cimg_mp_slot_nan,p1).move_to(code);
                _cimg_mp_return_nan();
              }

              // Regular expression.
              for (s = s0; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                ref.assign(7);
                pos = compile(s,ns,depth1,ref,block_flags);
                c1 = *ns; *ns = 0;
                variable_name.assign(CImg<charT>::string(s,true,true).unroll('y'),true);
                cimg::strpare(variable_name,false,true);
                if (is_const_scalar(pos)) // Const scalar
                  std::fprintf(cimg::output(),"\n[" cimg_appname "_math_parser] %s = %.17g "
                               "(mem[%u]: %s%s)",
                               variable_name._data,mem[pos],pos,s_type(pos)._data,s_ref(ref)._data);
                else // Vector or non-const scalar
                  std::fprintf(cimg::output(),"\n[" cimg_appname "_math_parser] %s = (uninitialized) "
                               "(mem[%u]: %s%s)",
                               variable_name._data,pos,s_type(pos)._data,s_ref(ref)._data);

                if (p_ref) std::memcpy(p_ref,ref,siz_ref);

                if (is_vector(pos)) // Vector
                  ((CImg<ulongT>::vector((ulongT)mp_vector_print,pos,0,(ulongT)size(pos),is_sth?1:0),
                    variable_name)>'y').move_to(opcode);
                else // Scalar
                  ((CImg<ulongT>::vector((ulongT)mp_print,pos,0,is_sth?1:0),
                    variable_name)>'y').move_to(opcode);

                opcode[2] = opcode._height;
                opcode.move_to(code);
                *ns = c1; s = ns;
              }
              _cimg_mp_return(pos);
            }
            break;

          case 'q' :
            if (!std::strncmp(ss,"qr(",3)) { // QR decomposition
              _cimg_mp_op("Function 'qr()'");
              s1 = ss3; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss3,s1,depth1,0,block_flags); // A
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags); // nb_colsA
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1; // is_reduced_form
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              _cimg_mp_check_const_scalar(arg3,3,2);

              p1 = size(arg1);
              p2 = (unsigned int)mem[arg2];
              p3 = p1/p2;
              arg3 = (unsigned int)mem[arg3];
              if (p3*p2!=p1) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of first argument ('%s') "
                                            "does not match with second argument 'nb_colsA=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,p2,s0);
              }
              pos = vector((p2 + p3)*(arg3?std::min(p2,p3):p3)); // Size of output
              CImg<ulongT>::vector((ulongT)mp_matrix_qr,pos,arg1,p2,p3,arg3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'r' :
            if (!std::strncmp(ss,"rad2deg(",8)) { // Degrees to radians
              _cimg_mp_op("Function 'rad2deg()'");
              arg1 = compile(ss8,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(rad2deg,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(mem[arg1]*180/cimg::PI);
              _cimg_mp_scalar1(rad2deg,arg1);
            }

            if ((cimg_sscanf(ss,"rand%u%c",&(arg1=~0U),&sep)==2 && sep=='(' && arg1>0) ||
                !std::strncmp(ss,"rand(#",6) ||
                (!std::strncmp(ss,"rand",4) && ss4<se1 && *ss4!='(' && (s=std::strchr(ss4,'('))!=0)) { // Random vector
              _cimg_mp_op("Function 'rand()'");
              p3 = 0;
              if (arg1==~0U && *ss4!='(') {
                arg1 = compile(ss4,s++,depth1,0,block_flags);
                _cimg_mp_check_const_scalar(arg1,0,3);
                arg1 = (unsigned int)mem[arg1];
              } else s = std::strchr(ss4,'(') + 1;

              if (arg1==~0U && *s=='#') { // Number of elements specified as first argument with '#'
                s0 = ++s; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                arg1 = compile(s,s0++,depth1,0,block_flags);
                _cimg_mp_check_const_scalar(arg1,1,3);
                arg1 = (unsigned int)mem[arg1];
                p3 = 1;
                s = s0;
              }

              arg2 = p2 = 0; arg3 = 1; arg4 = arg5 = ~0U;
              if (s<se1) {
                s1 = s + 1; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s,s1,depth1,0,block_flags);
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg2 = arg3;
                  arg3 = compile(s1,s2,depth1,0,block_flags);
                  if (s2<se1) {
                    s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                    arg4 = compile(s2,s1,depth1,0,block_flags);
                    arg5 = s1<se1?compile(++s1,se1,depth1,0,block_flags):~0U;
                    p2 = size(arg4);
                  }
                }
              }
              _cimg_mp_check_type(arg2,p3 + 1,1,0);
              _cimg_mp_check_type(arg3,p3 + 2,1,0);
              if (arg4!=~0U) _cimg_mp_check_type(arg4,p3 + 3,2,0);
              if (arg5!=~0U) _cimg_mp_check_type(arg5,p3 + 4,1,0);
              pos = vector(arg1);
              CImg<ulongT>::vector((ulongT)mp_vector_rand,pos,arg1,arg2,arg3,arg4,p2,arg5).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"ref(",4)) { // Variable declaration
              _cimg_mp_op("Function 'ref()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              if (s1>=se1 || !*s1) compile(s1,s1,depth1,0,block_flags); // Will throw missing argument error
              arg3 = compile(ss4,s1++,depth1,p_ref,block_flags|32);
              variable_name.assign(s1,(unsigned int)(se - s1)).back() = 0;
              cimg::strpare(variable_name,false,true);
              *se1 = 0;

              if (!cimg::is_varname(variable_name)) { // Invalid variable name
                cimg::strellipsize(variable_name,64);
                *se1 = ')';
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Invalid specified variable name '%s', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            variable_name._data,s0);
              }
              get_variable_pos(variable_name,arg1,arg2);
              if (arg2!=~0U) reserved_label[arg2] = arg3;
              else if (arg1!=~0U) variable_pos[arg1] = arg3;
              else { // New variable
                if (variable_def._width>=variable_pos._width) variable_pos.resize(-200,1,1,1,0);
                variable_pos[variable_def._width] = arg3;
                variable_name.move_to(variable_def);
              }
              if (is_vector(arg3))
                set_reserved_vector(arg3); // Prevent from being used in further optimization
              else if (is_comp_scalar(arg3)) memtype[arg3] = -1;
              *se1 = ')';
              _cimg_mp_return(arg3);
            }

            if (!std::strncmp(ss,"repeat(",7)) { // Repeat
              _cimg_mp_op("Function 'repeat()'");
              s0 = ss7; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
              arg1 = compile(ss7,s0,depth1,0,block_flags); // Number of iterations
              _cimg_mp_check_type(arg1,1,1,0);
              s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              p1 = code._width;

              if (s1<se1) { // Version with 3 arguments
                variable_name.assign(s0,(unsigned int)(s1 + 1 - s0)).back() = 0;
                cimg::strpare(variable_name,false,true);
                if (!cimg::is_varname(variable_name)) { // Invalid variable name
                  cimg::strellipsize(variable_name,64);
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Invalid loop variable name '%s', "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              variable_name._data,s0);
                }
                get_variable_pos(variable_name,arg2,arg3);
                arg2 = arg3!=~0U?reserved_label[arg3]:arg2!=~0U?variable_pos[arg2]:~0U; // Variable slot
                if (arg2!=~0U && (!is_scalar(arg2) ||
                                  is_const_scalar(arg2))) { // Variable is not a vector or is a constant->error
                  cimg::strellipsize(variable_name,64);
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Invalid type '%s' for variable '%s' "
                                              "(expected 'scalar'), in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              s_type(arg2)._data,variable_name._data,s0);
                } else if (arg2==~0U) { // Variable does not exist -> create it
                  arg2 = scalar();
                  if (arg3!=~0U) reserved_label[arg3] = arg2;
                  else {
                    if (variable_def._width>=variable_pos._width) variable_pos.resize(-200,1,1,1,0);
                    variable_pos[variable_def._width] = arg2;
                    variable_name.move_to(variable_def);
                  }
                  memtype[arg2] = -1;
                }
                arg3 = compile(++s1,se1,depth1,0,block_flags);
              } else { // Version with 2 arguments
                arg2 = ~0U;
                arg3 = compile(s0,se1,depth1,0,block_flags);
              }
              // arg2 = variable slot, arg3 = fill expression.
              CImg<ulongT>::vector((ulongT)mp_repeat,arg3,arg1,arg2,code._width - p1).move_to(code,p1);
              _cimg_mp_return_nan();
            }

            if (!std::strncmp(ss,"resize(",7)) { // Vector or image resize
              _cimg_mp_op("Function 'resize()'");
              if (*ss7!='#') { // Vector
                pos = 1;
                for (s = ss7; s<se; ++s, ++pos) {
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                  arg2 = compile(s,ns,depth1,0,block_flags);
                  if (s!=ss7) _cimg_mp_check_type(arg2,pos,1,0);
                  CImg<ulongT>::vector(arg2).move_to(l_opcode);
                  s = ns;
                }
                (l_opcode>'y').move_to(opcode);
                if (opcode.height()<2) compile(s,se1,depth1,0,block_flags); // Not enough arguments -> throw exception
                arg1 = (unsigned int)opcode[0]; // Vector to resize
                p1 = size(arg1);

                if (opcode.height()<=4) { // Simple vector resize
                  arg2 = (unsigned int)opcode[1];
                  _cimg_mp_check_const_scalar(arg2,2,3);
                  arg2 = (unsigned int)mem[arg2];
                  arg3 = opcode.height()<3?1U:(unsigned int)opcode[2];
                  _cimg_mp_check_type(arg3,3,1,0);
                  arg4 = opcode.height()<4?0U:(unsigned int)opcode[3];
                  _cimg_mp_check_type(arg4,4,1,0);
                  if (p1 && p1==arg2) // Particular case: copy input (same size)
                    pos = copy(arg1);
                  else {
                    pos = vector(arg2);
                    CImg<ulongT>::vector((ulongT)mp_vector_resize,pos,arg2,arg1,p1,arg3,arg4).move_to(code);
                  }
                } else { // Advanced vector resize (vector viewed as an image)
                  // opcode = [ A, ow,oh,od,os, nw,nh,nd,ns, interp, boundary_cond, ax,ay,az,ac ]
                  //          [ 0   1  2  3  4   5  6  7  8       9             10  11 12 13 14 ]

                  if (opcode.height()<6) compile(s,se1,depth1,0,block_flags); // Not enough arguments -> throw exception
                  p2 = opcode.height();
                  opcode.resize(1,15,1,1,0);
                  if (p2<7) opcode[6] = opcode[2];
                  if (p2<8) opcode[7] = opcode[3];
                  if (p2<9) opcode[8] = opcode[4];
                  if (p2<10) opcode[9] = 1;
                  _cimg_mp_check_const_scalar(opcode[1],2,3);
                  _cimg_mp_check_const_scalar(opcode[2],3,3);
                  _cimg_mp_check_const_scalar(opcode[3],4,3);
                  _cimg_mp_check_const_scalar(opcode[4],5,3);
                  _cimg_mp_check_const_scalar(opcode[5],6,3);
                  _cimg_mp_check_const_scalar(opcode[6],7,3);
                  _cimg_mp_check_const_scalar(opcode[7],8,3);
                  _cimg_mp_check_const_scalar(opcode[8],9,3);
                  arg2 = (unsigned int)mem[opcode[1]]; opcode[1] = arg2;
                  arg3 = (unsigned int)mem[opcode[2]]; opcode[2] = arg3;
                  arg4 = (unsigned int)mem[opcode[3]]; opcode[3] = arg4;
                  arg5 = (unsigned int)mem[opcode[4]]; opcode[4] = arg5;
                  if (arg2*arg3*arg4*arg5!=std::max(1U,p1)) {
                    _cimg_mp_strerr;
                    throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                                "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                                "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                                pixel_type(),_cimg_mp_calling_function,s_op,
                                                std::max(p1,1U),arg2,arg3,arg4,arg5,arg2*arg3*arg4*arg5);
                  }
                  arg2 = (unsigned int)mem[opcode[5]]; opcode[5] = arg2;
                  arg3 = (unsigned int)mem[opcode[6]]; opcode[6] = arg3;
                  arg4 = (unsigned int)mem[opcode[7]]; opcode[7] = arg4;
                  arg5 = (unsigned int)mem[opcode[8]]; opcode[8] = arg5;
                  if (arg2==opcode[1] && arg3==opcode[2] && arg4==opcode[3] && arg5==opcode[4]) // Particular case: copy
                    pos = copy(arg1);
                  else {
                    pos = vector(arg2*arg3*arg4*arg5);
                    opcode.resize(1,18,1,1,0,0,0,1);
                    opcode[0] = (ulongT)mp_vector_resize_ext;
                    opcode[1] = (ulongT)pos;
                    opcode[2] = (ulongT)p1;
                    opcode.move_to(code);
                  }
                }
                return_comp = true;
                _cimg_mp_return(pos);

              } else { // Image
                if (!is_inside_critical) is_parallelizable = false;
                s0 = ss8; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                p1 = compile(ss8,s0++,depth1,0,block_flags);
                _cimg_mp_check_list();
                l_opcode.assign(); // Don't use 'opcode': it can be modified by further calls to 'compile()'!
                CImg<ulongT>::vector((ulongT)mp_image_resize,_cimg_mp_slot_nan,p1,~0U,~0U,~0U,~0U,1,0,0,0,0,0).
                  move_to(l_opcode);
                pos = 0;
                for (s = s0; s<se && pos<10; ++s) {
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                  arg1 = compile(s,ns,depth1,0,block_flags);
                  _cimg_mp_check_type(arg1,pos + 2,1,0);
                  l_opcode(0,pos + 3) = arg1;
                  s = ns;
                  ++pos;
                }
                if (pos<1 || pos>10) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: %s arguments, in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              pos<1?"Missing":"Too many",s0);
                }
                l_opcode[0].move_to(code);
                _cimg_mp_return_nan();
              }
            }

            if (!std::strncmp(ss,"reverse(",8)) { // Vector reverse
              _cimg_mp_op("Function 'reverse()'");
              arg1 = compile(ss8,se1,depth1,0,block_flags);
              if (!is_vector(arg1)) _cimg_mp_same(arg1);
              p1 = size(arg1);
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_reverse,pos,arg1,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"rol(",4) || !std::strncmp(ss,"ror(",4)) { // Bitwise rotation
              _cimg_mp_op(ss[2]=='l'?"Function 'rol()'":"Function 'ror()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1-expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg2,2,1,0);
              if (is_vector(arg1)) {
                if (*ss2=='l') { _cimg_mp_vector2(rol,arg1,arg2); }
                else { _cimg_mp_vector2(ror,arg1,arg2); }
              }
              if (is_const_scalar(arg1) && is_const_scalar(arg2))
                _cimg_mp_const_scalar(*ss2=='l'?cimg::rol(mem[arg1],(unsigned int)mem[arg2]):
                                      cimg::ror(mem[arg1],(unsigned int)mem[arg2]));
              _cimg_mp_return(scalar2(*ss2=='l'?mp_rol:mp_ror,arg1,arg2));
            }

            if (!std::strncmp(ss,"rot(",4)) { // 2D/3D rotation matrix
              _cimg_mp_op("Function 'rot()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              if (s1<se1) { // 3D rotation
                _cimg_mp_check_type(arg1,1,3,3);
                is_sth = false; // Is coordinates as vector?
                if (is_vector(arg1)) { // Coordinates specified as a vector
                  is_sth = true;
                  p2 = size(arg1);
                  ++arg1;
                  arg2 = arg3 = 0;
                  if (p2>1) {
                    arg2 = arg1 + 1;
                    if (p2>2) arg3 = arg2 + 1;
                  }
                  arg4 = compile(++s1,se1,depth1,0,block_flags);
                } else {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg2 = compile(s1,s2,depth1,0,block_flags);
                  s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                  arg3 = compile(s2,s3,depth1,0,block_flags);
                  arg4 = compile(++s3,se1,depth1,0,block_flags);
                  _cimg_mp_check_type(arg2,2,1,0);
                  _cimg_mp_check_type(arg3,3,1,0);
                }
                _cimg_mp_check_type(arg4,is_sth?2:4,1,0);
                pos = vector(9);
                CImg<ulongT>::vector((ulongT)mp_rot3d,pos,arg1,arg2,arg3,arg4).move_to(code);
              } else { // 2D rotation
                _cimg_mp_check_type(arg1,1,1,0);
                pos = vector(4);
                CImg<ulongT>::vector((ulongT)mp_rot2d,pos,arg1).move_to(code);
              }
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"round(",6)) { // Value rounding
              _cimg_mp_op("Function 'round()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              arg2 = 1;
              arg3 = 0;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              if (is_vector(arg1)) _cimg_mp_vector3(round,arg1,arg2,arg3);
              if (is_const_scalar(arg1) && is_const_scalar(arg2) && is_const_scalar(arg3))
                _cimg_mp_const_scalar(cimg::round(mem[arg1],mem[arg2],(int)mem[arg3]));
              _cimg_mp_scalar3(round,arg1,arg2,arg3);
            }

#ifdef cimg_mp_func_run
            if (!std::strncmp(ss,"run(",4)) { // Run external command
              _cimg_mp_op("Function 'run()'");
              if (!is_inside_critical && !is_inside_begin && !is_inside_end) is_noncritical_run = true;
              CImg<ulongT>::vector((ulongT)mp_run,0,0).move_to(l_opcode);
              pos = 1;
              for (s = ss4; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg1 = compile(s,ns,depth1,0,block_flags);
                CImg<ulongT>::vector(arg1,size(arg1)).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              pos = scalar();
              opcode[1] = pos;
              opcode[2] = (opcode._height - 3)/2;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
#endif
            break;

          case 's' :
            if (*ss1=='(') { // Image spectrum
              _cimg_mp_op("Function 's()'");
              if (*ss2=='#') { // Index specified
                p1 = compile(ss3,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss3);
                _cimg_mp_check_list();
              } else { if (ss2!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_spectrum,p1);
            }

            if (!std::strncmp(ss,"s2v(",4)) { // String to double
              _cimg_mp_op("Function 's2v()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = arg3 = 0;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
              }
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              p1 = size(arg1);
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_s2v,pos,arg1,p1,arg2,arg3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"same(",5)) { // Test if operands have the same values
              _cimg_mp_op("Function 'same()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = 11;
              arg4 = 1;
              if (s2<se1) {
                s3 = ++s2; while (s3<se1 && (*s3!=',' || level[s3 - expr._data]!=clevel1)) ++s3;
                arg3 = compile(s2,s3,depth1,0,block_flags);
                _cimg_mp_check_type(arg3,3,1,0);
                arg4 = s3<se1?compile(++s3,se1,depth1,0,block_flags):1;
              }
              p1 = size(arg1);
              p2 = size(arg2);
              _cimg_mp_scalar6(vector_eq,arg1,p1,arg2,p2,arg3,arg4);
            }

#ifdef cimg_mp_func_set
            if (!std::strncmp(ss,"set(",4)) { // Set value to external variable
              _cimg_mp_op("Function 'set()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              p1 = size(arg1);
              p2 = size(arg2);
              CImg<ulongT>::vector((ulongT)mp_set,arg2,p2,arg1,p1).move_to(code);
              _cimg_mp_return_nan();
            }
#endif

            if (!std::strncmp(ss,"shift(",6)) { // Shift vector
              _cimg_mp_op("Function 'shift()'");

              // Parse list of arguments.
              CImg<unsigned int> args(12,1,1,1,0);
              p1 = 0;
              for (s = ss6; s<se && p1<9; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg1 = compile(s,ns,depth1,0,block_flags);
                args[p1++] = arg1;
                s = ns;
              }
              if (s<se1) args[p1++] = compile(s,se1,depth1,0,block_flags); // Last argument

              if (p1<4) { // Shift vector
                if (p1<1) compile(s,se1,depth1,0,block_flags); // -> Error, missing arguments
                arg1 = args[0];
                arg2 = p1>1?args[1]:1;
                arg3 = p1>2?args[2]:0;
                _cimg_mp_check_type(arg1,1,2,0);
                _cimg_mp_check_type(arg2,2,1,0);
                _cimg_mp_check_type(arg3,3,1,0);
                p1 = size(arg1);
                pos = vector(p1);
                CImg<ulongT>::vector((ulongT)mp_shift,pos,arg1,p1,arg2,arg3).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              } else { // Shift image-valued vector
                if (p1<5) compile(s,se1,depth1,0,block_flags); // -> Error, missing arguments
                _cimg_mp_check_type(args[0],1,2,0); // I
                _cimg_mp_check_const_scalar(args[1],2,3); // w
                _cimg_mp_check_const_scalar(args[2],3,3); // h
                _cimg_mp_check_const_scalar(args[3],4,3); // d
                _cimg_mp_check_const_scalar(args[4],5,3); // s
                args[1] = mem[args[1]];
                args[2] = mem[args[2]];
                args[3] = mem[args[3]];
                args[4] = mem[args[4]];
                arg1 = p1>5?args[5]:1; // dx
                arg2 = p1>6?args[6]:0; // dy
                arg3 = p1>7?args[7]:0; // dz
                arg4 = p1>8?args[8]:0; // dc
                arg5 = p1>9?args[9]:0; // boundary_conditions
                _cimg_mp_check_type(arg1,6,1,0);
                _cimg_mp_check_type(arg2,7,1,0);
                _cimg_mp_check_type(arg3,8,1,0);
                _cimg_mp_check_type(arg4,9,1,0);
                _cimg_mp_check_type(arg5,10,1,0);
                p1 = size(args[0]);
                p2 = args[1]*args[2]*args[3]*args[4];
                if (p1!=p2) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Vector size (%u values) and its specified "
                                              "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              std::max(p1,1U),args[1],args[2],args[3],args[4],
                                              args[1]*args[2]*args[3]*args[4]);
                }
                pos = vector(p1);
                CImg<ulongT>::vector((ulongT)mp_image_shift,pos,args[0],
                                     args[1],args[2],args[3],args[4],
                                     arg1,arg2,arg3,arg4,arg5).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }
            }

            if (!std::strncmp(ss,"sigmoid(",8)) { // Sigmoid
              _cimg_mp_op("Function 'sigmoid()'");
              arg1 = compile(ss8,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sigmoid,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::sigmoid(mem[arg1]));
              _cimg_mp_scalar1(sigmoid,arg1);
            }

            if (!std::strncmp(ss,"sign(",5)) { // Sign
              _cimg_mp_op("Function 'sign()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sign,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::sign(mem[arg1]));
              _cimg_mp_scalar1(sign,arg1);
            }

            if (!std::strncmp(ss,"sin(",4)) { // Sine
              _cimg_mp_op("Function 'sin()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sin,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::sin(mem[arg1]));
              _cimg_mp_scalar1(sin,arg1);
            }

            if (!std::strncmp(ss,"sinc(",5)) { // Sine cardinal
              _cimg_mp_op("Function 'sinc()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sinc,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::sinc(mem[arg1]));
              _cimg_mp_scalar1(sinc,arg1);
            }

            if (!std::strncmp(ss,"sinh(",5)) { // Hyperbolic sine
              _cimg_mp_op("Function 'sinh()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sinh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::sinh(mem[arg1]));
              _cimg_mp_scalar1(sinh,arg1);
            }

            if (!std::strncmp(ss,"size(",5)) { // Vector size
              _cimg_mp_op("Function 'size()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              _cimg_mp_const_scalar(is_scalar(arg1)?0:size(arg1));
            }

            if (!std::strncmp(ss,"softargmax(",11) || // Softargmax & Softargmin
                !std::strncmp(ss,"softargmin(",11)) {
              _cimg_mp_op(*ss8=='a'?"Function 'softargmax()'":"Function 'softargmin()'");
              s0 = ss + 11;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg2,2,1,0);
              p1 = size(arg1);
              if (!p1) _cimg_mp_return(0);
              _cimg_mp_return(scalar3(*ss8=='a'?mp_softargmax:mp_softargmin,arg1,p1,arg2));
            }

            if (!std::strncmp(ss,"softmax(",8) || !std::strncmp(ss,"softmin(",8)) { // Softmax & Softmin
              _cimg_mp_op(*ss5=='a'?"Function 'softmax()'":"Function 'softmin()'");
              s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss8,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg2,2,1,0);
              p1 = size(arg1);
              if (!p1) _cimg_mp_return(1);
              pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(p1));
              CImg<ulongT>::vector((ulongT)(*ss5=='a'?mp_softmax:mp_softmin),pos,arg1,p1,arg2).move_to(code);
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"solve(",6)) { // Solve square linear system
              _cimg_mp_op("Function 'solve()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_type(arg2,2,2,0);
              _cimg_mp_check_const_scalar(arg3,3,3);
              p1 = size(arg1);
              p2 = size(arg2);
              p3 = (unsigned int)mem[arg3];
              arg5 = p2/p3;
              if (!arg5 || (arg6 = p1/arg5)*arg5!=p1 || arg5*p3!=p2) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Types of first and second arguments ('%s' and '%s') "
                                            "do not match the third argument 'nb_colsB=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,s_type(arg2)._data,p3,s0);
              }
              pos = vector(arg6*p3);
              CImg<ulongT>::vector((ulongT)mp_solve,pos,arg1,arg2,arg6,arg5,p3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"sort(",5)) { // Sort vector
              _cimg_mp_op("Function 'sort()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags); // X
              arg2 = arg5 = 1; arg3 = arg6 = 0; arg4 = ~0U;
              if (s1<se1) {
                s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                arg2 = compile(s1,s0,depth1,0,block_flags); // is_increasing
                if (s0<se1) {
                  s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg3 = compile(s0,s1,depth1,0,block_flags); // starting_index
                  if (s1<se1) {
                    s0 = ++s1; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                    arg4 = compile(s1,s0,depth1,0,block_flags); // nb_elt
                    if (s0<se1) {
                      s1 = ++s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                      arg5 = compile(s0,s1,depth1,0,block_flags); // size_elt
                      arg6 = s1<se1?compile(++s1,se1,depth1,0,block_flags):0; // sort_index
                    }
                  }
                }
              }
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_type(arg2,2,1,0);
              _cimg_mp_check_type(arg3,3,1,0);
              if (arg4!=~0U) _cimg_mp_check_type(arg4,4,1,0);
              _cimg_mp_check_type(arg5,5,1,0);
              _cimg_mp_check_type(arg6,6,1,0);
              p1 = size(arg1);
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_sort,pos,arg1,p1,arg2,arg3,arg4,arg5,arg6).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"sqr(",4)) { // Square
              _cimg_mp_op("Function 'sqr()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sqr,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::sqr(mem[arg1]));
              _cimg_mp_scalar1(sqr,arg1);
            }

            if (!std::strncmp(ss,"sqrt(",5)) { // Square root
              _cimg_mp_op("Function 'sqrt()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(sqrt,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::sqrt(mem[arg1]));
              _cimg_mp_scalar1(sqrt,arg1);
            }

            if (!std::strncmp(ss,"srand(",6)) { // Set RNG seed
              _cimg_mp_op("Function 'srand()'");
              arg1 = ss6<se1?compile(ss6,se1,depth1,0,block_flags):~0U;
              if (arg1!=~0U) { _cimg_mp_check_type(arg1,1,1,0); _cimg_mp_scalar1(srand,arg1); }
              _cimg_mp_scalar0(srand0);
            }

            if (!std::strncmp(ss,"stats(",6)) { // Image/vector statistics
              _cimg_mp_op("Function 'stats()'");
              if (*ss6!='#' && ss6!=se1) { // Vector
                s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg1 = compile(ss6,s1,depth1,0,block_flags); // Vector
                _cimg_mp_check_type(arg1,1,2,0);
                p1 = size(arg1);
                arg2 = arg3 = arg4 = arg5 = 1;
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg2 = compile(s1,s2,depth1,0,block_flags); // Width
                  _cimg_mp_check_const_scalar(2,arg2,3);
                  arg2 = (unsigned int)mem[arg2];
                  if (s2<se1) {
                    s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                    arg3 = compile(s2,s1,depth1,0,block_flags); // Height
                    _cimg_mp_check_const_scalar(3,arg3,3);
                    arg3 = (unsigned int)mem[arg3];
                    if (s1<se1) {
                      s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                      arg4 = compile(s1,s2,depth1,0,block_flags); // Depth
                      _cimg_mp_check_const_scalar(4,arg4,3);
                      arg4 = (unsigned int)mem[arg4];
                      arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0; // Spectrum
                      _cimg_mp_check_const_scalar(5,arg5,3);
                      arg5 = (unsigned int)mem[arg5];
                    }
                  }
                } else arg2 = p1;
                p2 = arg2*arg3*arg4*arg5;
                if (p1!=p2) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: Vector size (%u values) and its specified "
                                              "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              std::max(p1,1U),arg2,arg3,arg4,arg5,p2);
                }
                pos = vector(15);
                CImg<ulongT>::vector((ulongT)mp_vector_stats,pos,arg1,arg2,arg3,arg4,arg5).move_to(code);
              } else { // Image
                if (*ss6=='#') { // Index specified
                  p1 = compile(ss7,se1,depth1,0,block_flags);
                  _cimg_mp_check_notnan_index(p1,ss7);
                  _cimg_mp_check_list();
                } else { if (ss6!=se1) break; p1 = ~0U; }
                pos = vector(15);
                CImg<ulongT>::vector((ulongT)mp_image_stats,pos,p1).move_to(code);
              }
              return_comp = true;
              _cimg_mp_return(pos);
            }

#ifdef cimg_mp_func_store
            if (!std::strncmp(ss,"store(",6)) { // Store vector to variable
              _cimg_mp_op("Function 'store()'");
              s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss6,s1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,2,2,0);
              p1 = size(arg1);
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              p2 = size(arg2);
              p3 = std::max(1U,p2);

              arg3 = ~0U; arg4 = arg5 = arg6 = 1U; pos = 0;
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                _cimg_mp_check_type(arg3,3,1,0);
                arg4 = arg5 = arg6 = 1U;
                if (s1<se1) {
                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                  arg4 = compile(s1,s2,depth1,0,block_flags);
                  _cimg_mp_check_type(arg4,4,1,0);
                  if (s2<se1) {
                    s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                    arg5 = compile(s2,s1,depth1,0,block_flags);
                    _cimg_mp_check_type(arg5,5,1,0);
                    if (s1<se1) {
                      s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                      arg6 = compile(s1,s2,depth1,0,block_flags);
                      pos = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;
                      _cimg_mp_check_type(arg6,6,1,0);
                      _cimg_mp_check_type(pos,7,1,0);
                    }
                  }
                }
              }
              if (arg3==~0U) arg3 = const_scalar(p3);
              CImg<ulongT>::vector((ulongT)mp_store,_cimg_mp_slot_nan,arg2,p2,arg1,p1,
                                   arg3,arg4,arg5,arg6,pos).move_to(code);
              _cimg_mp_return_nan();
            }
#endif


            if (!std::strncmp(ss,"string(",7)) { // Construct string from list of arguments
              _cimg_mp_op("Function 'string()'");
              CImg<ulongT>::vector((ulongT)mp_string,0,0,0).move_to(l_opcode);

              if (*ss7=='#') { // Output vector size specified with '#'
                s0 = ss8; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                arg1 = compile(ss8,s0++,depth1,0,block_flags);
                _cimg_mp_check_const_scalar(arg1,1,3);
                arg1 = (unsigned int)mem[arg1];
                s = s0;
              } else { arg1=~0U; s = ss7; }

              p1 = 0;
              for (; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                p2 = size(arg2);
                if (p2) p1+=p2;
                else {
                  if (is_const_scalar(arg2)) p1+=cimg_snprintf(variable_name.assign(24),24,"%.17g",mem[arg2]);
                  else p1+=23;
                }
                CImg<ulongT>::vector(arg2,p2).move_to(l_opcode);
                s = ns;
              }
              if (arg1==~0U) arg1 = p1;
              pos = vector(arg1,0);
              (l_opcode>'y').move_to(opcode);
              opcode[1] = pos;
              opcode[2] = arg1;
              opcode[3] = (opcode._height - 3)/2;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"svd(",4)) { // Matrix SVD
              _cimg_mp_op("Function 'svd()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              p1 = size(arg1);
              p2 = (unsigned int)mem[arg2];
              p3 = p1/p2;
              if (p3*p2!=p1) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Type of first argument ('%s') "
                                            "does not match with second argument 'nb_colsA=%u', "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,p2,s0);
              }
              pos = vector(p1 + p2 + p2*p2);
              CImg<ulongT>::vector((ulongT)mp_matrix_svd,pos,arg1,p2,p3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"swap(",5)) { // Swap values
              _cimg_mp_op("Function 'swap()'");

              if (*ss5=='#') { // Swap image values
                s0 = ss6; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0; // #ind
                p1 = compile(ss6,s0++,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
                s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1; // pos0
                arg1 = compile(s0,s1,depth1,0,block_flags);
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2; // pos1
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0; // is_vector?
                CImg<ulongT>::vector((ulongT)mp_image_swap,_cimg_mp_slot_nan,p1,arg1,arg2,arg3).move_to(code);

              } else {
                s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                ref.assign(14);
                arg1 = compile(ss5,s1,depth1,ref,block_flags);
                arg2 = compile(++s1,se1,depth1,ref._data + 7,block_flags);
                p1 = size(arg1);
                _cimg_mp_check_type(arg2,2,p1?2:1,p1);
                if (is_const_scalar(arg1) || is_const_scalar(arg2)) {
                  _cimg_mp_strerr;
                  throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                              "CImg<%s>::%s: %s: %s argument cannot be a constant, "
                                              "in expression '%s'.",
                                              pixel_type(),_cimg_mp_calling_function,s_op,
                                              is_const_scalar(arg1)?"First":"Second",s0);
                }
                CImg<ulongT>::vector((ulongT)mp_swap,arg1,arg2,p1).move_to(code);

                // Write back values of linked arg1 and arg2.
                const unsigned int *_ref = ref;
                is_sth = true; // Is first argument?
                do {
                  switch (*_ref) {
                  case 1 : // arg1: V[k]
                    arg3 = _ref[1]; // Vector slot
                    arg4 = _ref[2]; // Index
                    CImg<ulongT>::vector((ulongT)mp_vector_set_off,arg1,arg3,(ulongT)size(arg3),arg4).
                      move_to(code);
                    break;
                  case 2 : // arg1: i/j[_#ind,off]
                    if (!is_inside_critical) is_parallelizable = false;
                    p1 = _ref[1]; // Index
                    is_relative = (bool)_ref[2];
                    arg3 = _ref[3]; // Offset
                    if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                      CImg<ulongT>::vector((ulongT)mp_set_ijoff,arg1,(ulongT)is_relative,
                                           p1,arg3).move_to(code);
                    break;
                  case 3 : // arg1: i/j(_#ind,_x,_y,_z,_c)
                    if (!is_inside_critical) is_parallelizable = false;
                    p1 = _ref[1]; // Index
                    is_relative = (bool)_ref[2];
                    arg3 = _ref[3]; // X
                    arg4 = _ref[4]; // Y
                    arg5 = _ref[5]; // Z
                    arg6 = _ref[6]; // C
                    if ((p1==~0U && imgout) || (p1!=~0U && imglist))
                      CImg<ulongT>::vector((ulongT)mp_set_ijxyzc,arg1,(ulongT)is_relative,
                                           p1,arg3,arg4,arg5,arg6).move_to(code);
                    break;
                  case 4: // arg1: I/J[_#ind,off]
                    if (!is_inside_critical) is_parallelizable = false;
                    p1 = _ref[1]; // Index
                    is_relative = (bool)_ref[2];
                    arg3 = _ref[3]; // Offset
                    if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                      if (is_scalar(arg1))
                        CImg<ulongT>::vector((ulongT)mp_set_IJoff_s,arg1,(ulongT)is_relative,
                                             p1,arg3).move_to(code);
                      else {
                        _cimg_mp_check_const_index(p1);
                        CImg<ulongT>::vector((ulongT)mp_set_IJoff_v,arg1,(ulongT)is_relative,
                                             p1,arg3,size(arg1)).move_to(code);
                      }
                    }
                    break;
                  case 5 : // arg1: I/J(_#ind,_x,_y,_z,_c)
                    if (!is_inside_critical) is_parallelizable = false;
                    p1 = _ref[1]; // Index
                    is_relative = (bool)_ref[2];
                    arg3 = _ref[3]; // X
                    arg4 = _ref[4]; // Y
                    arg5 = _ref[5]; // Z
                    if ((p1==~0U && imgout) || (p1!=~0U && imglist)) {
                      if (is_scalar(arg1))
                        CImg<ulongT>::vector((ulongT)mp_set_IJxyz_s,arg1,(ulongT)is_relative,
                                             p1,arg3,arg4,arg5).move_to(code);
                      else {
                        _cimg_mp_check_const_index(p1);
                        CImg<ulongT>::vector((ulongT)mp_set_IJxyz_v,arg1,(ulongT)is_relative,
                                             p1,arg3,arg4,arg5,size(arg1)).move_to(code);
                      }
                    }
                    break;
                  }

                  _ref+=7;
                  arg1 = arg2;
                  is_sth = !is_sth;
                } while (!is_sth);

                if (p_ref) std::memcpy(p_ref,ref,siz_ref);
              }

              _cimg_mp_return_nan();
            }
            break;

          case 't' :
            if (!std::strncmp(ss,"tan(",4)) { // Tangent
              _cimg_mp_op("Function 'tan()'");
              arg1 = compile(ss4,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(tan,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::tan(mem[arg1]));
              _cimg_mp_scalar1(tan,arg1);
            }

            if (!std::strncmp(ss,"tanh(",5)) { // Hyperbolic tangent
              _cimg_mp_op("Function 'tanh()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(tanh,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(std::tanh(mem[arg1]));
              _cimg_mp_scalar1(tanh,arg1);
            }

            if (!std::strncmp(ss,"trace(",6)) { // Matrix trace
              _cimg_mp_op("Function 'trace()'");
              arg1 = compile(ss6,se1,depth1,0,block_flags);
              _cimg_mp_check_matrix_square(arg1,1);
              p1 = (unsigned int)cimg::round(std::sqrt((float)size(arg1)));
              _cimg_mp_scalar2(trace,arg1,p1);
            }

            if (!std::strncmp(ss,"transpose(",10)) { // Matrix transpose
              _cimg_mp_op("Function 'transpose()'");
              s1 = ss + 10; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss + 10,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,2,0);
              _cimg_mp_check_const_scalar(arg2,2,3);
              p1 = size(arg1);
              p2 = (unsigned int)mem[arg2];
              p3 = p1/p2;
              if (p2*p3!=p1) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Size of first argument ('%s') does not match "
                                            "second argument 'nb_cols=%u', in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            s_type(arg1)._data,p2,s0);
              }
              pos = vector(p3*p2);
              CImg<ulongT>::vector((ulongT)mp_transpose,pos,arg1,p2,p3).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'u' :
            if (!std::strncmp(ss,"ui2f(",5)) { // Special uint->float[16,32] conversion
              _cimg_mp_op("Function 'ui2f()'");
              arg1 = compile(ss5,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(ui2f,arg1);
              if (is_const_scalar(arg1))
                _cimg_mp_const_scalar((double)cimg::uint2float(mem[arg1],(T)0));
              _cimg_mp_scalar1(ui2f,arg1);
            }

            if (!std::strncmp(ss,"unitnorm(",9)) { // Normalize vector to unit norm
              _cimg_mp_op("Function 'unitnorm()'");
              s0 = ss + 9;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):2;
              _cimg_mp_check_type(arg2,2,1,0);
              p1 = size(arg1);
              if (p1>0) pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(p1));
              else {
                pos = scalar();
                if (is_const_scalar(arg1) && is_const_scalar(arg2)) {
                  val = mem[arg1];
                  _cimg_mp_const_scalar(val?(mem[arg2]?1:val):0);
                }
              }
              CImg<ulongT>::vector((ulongT)mp_unitnorm,pos,arg1,p1,arg2).move_to(code);
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"unref(",6)) { // Un-reference variable
              _cimg_mp_op("Function 'unref()'");
              arg1=~0U;
              for (s0 = ss6; s0<se1; s0 = s1) {
                if (s0>ss6 && *s0==',') ++s0;
                s1 = s0; while (s1<se1 && *s1!=',') ++s1;
                c1 = *s1;
                if (s1>s0) {
                  *s1 = 0;
                  get_variable_pos(s0,arg1,arg2);
                  if (arg2!=~0U) reserved_label[arg2] = ~0U;
                  else if (arg1!=~0U) {
                    variable_def.remove(arg1);
                    if (arg1<variable_pos._width - 1)
                      std::memmove(variable_pos._data + arg1,variable_pos._data + arg1 + 1,
                                   sizeof(uintT)*(variable_pos._width - arg1 - 1));
                    --variable_pos._width;
                  }
                  *s1 = c1;
                } else compile(s0,s1,depth1,0,block_flags); // Will throw a 'missing argument' exception
              }
              _cimg_mp_return(arg1!=~0U?arg1:_cimg_mp_slot_nan); // Return value of last specified variable
            }

            if (!std::strncmp(ss,"uppercase(",10)) { // Upper case
              _cimg_mp_op("Function 'uppercase()'");
              arg1 = compile(ss + 10,se1,depth1,0,block_flags);
              if (is_vector(arg1)) _cimg_mp_vector1(uppercase,arg1);
              if (is_const_scalar(arg1)) _cimg_mp_const_scalar(cimg::uppercase(mem[arg1]));
              _cimg_mp_scalar1(uppercase,arg1);
            }
            break;

          case 'v' :
            if (!std::strncmp(ss,"v2s(",4)) { // Double(s) to string
              _cimg_mp_op("Function 'v2s()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = 0; arg3 = ~0U;
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg2 = compile(s1,s2,depth1,0,block_flags);
                arg3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):~0U;
              }
              _cimg_mp_check_type(arg2,2,1,0);
              if (arg3==~0U) { // Auto-guess best output vector size
                p1 = size(arg1);
                p1 = p1?25*p1 - 1:24;
              } else {
                _cimg_mp_check_const_scalar(arg3,3,3);
                p1 = (unsigned int)mem[arg3];
              }
              pos = vector(p1);
              CImg<ulongT>::vector((ulongT)mp_v2s,pos,p1,arg1,size(arg1),arg2).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if ((cimg_sscanf(ss,"vector%u%c",&(arg1=~0U),&sep)==2 && sep=='(' && arg1>0) ||
                !std::strncmp(ss,"vector(",7) ||
                (!std::strncmp(ss,"vector",6) && ss7<se1 && (s=std::strchr(ss7,'('))!=0)) { // Vector
              _cimg_mp_op("Function 'vector()'");
              arg2 = 0; // Number of specified values
              if (arg1==~0U && *ss6!='(') {
                arg1 = compile(ss6,s++,depth1,0,block_flags);
                _cimg_mp_check_const_scalar(arg1,0,3);
                arg1 = (unsigned int)mem[arg1];
              } else s = std::strchr(ss6,'(') + 1;

              if (arg1==~0U && *s=='#') { // Number of elements specified as first argument with '#'
                s0 = ++s; while (s0<se1 && (*s0!=',' || level[s0 - expr._data]!=clevel1)) ++s0;
                arg1 = compile(s,s0++,depth1,0,block_flags);
                _cimg_mp_check_const_scalar(arg1,1,3);
                arg1 = (unsigned int)mem[arg1];
                s = s0;
              }

              is_sth = !is_new_variable_assignment; // Can vector be defined once in 'begin()'?
              arg4 = 0; // Output vector size
              CImg<ulongT>::vector((ulongT)mp_vector_init,0,0,0).move_to(l_opcode);
              while (*s && cimg::is_blank(*s)) ++s;
              if (s>=se1 && arg1==~0U) _cimg_mp_return(0); // Empty initializer
              if (s<se1) for (; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                const CImgList<ulongT> &rcode = is_inside_begin?code:code_begin;
                p1 = rcode.size();
                p2 = variable_def.size();
                arg2 = compile(s,ns,depth1,0,block_flags);
                p3 = rcode.size();
                if (is_vector(arg2)) {
                  arg3 = size(arg2);
                  arg4+=arg3;
                  CImg<ulongT>::vector(arg2,arg3).move_to(l_opcode);
                  const CImg<ulongT> &rcode_back = rcode.back();
                  is_sth&=p3>p1 && rcode_back[1]==arg2 &&
                    (rcode_back[0]==(ulongT)mp_string_init ||
                     rcode_back[0]==(ulongT)mp_vector_init) && variable_def.size()==p2 && !is_comp_vector(arg2);
                  // ^^ Tricky part: detect if 'arg2' is a newly constructed vector not assigned to a variable
                  // (i.e. a vector-valued literal).
                } else {
                  ++arg4;
                  CImg<ulongT>::vector(arg2,0).move_to(l_opcode);
                  is_sth&=is_const_scalar(arg2);
                }
                s = ns;
              }

              if (arg1==~0U) arg1 = arg4;
              pos = vector(arg1);
              (l_opcode>'y').move_to(opcode);
              opcode[1] = pos;
              opcode[2] = arg1;
              opcode[3] = (opcode._height - 4)/2;
              opcode.move_to(!is_sth || is_inside_begin || is_new_variable_assignment?code:code_begin);
              return_comp = !is_sth && is_new_variable_assignment;
              if (!return_comp) set_reserved_vector(pos); // Prevent from being used in further optimization
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"vmax(",5) || !std::strncmp(ss,"vmin(",5) ||
                !std::strncmp(ss,"vmaxabs(",8) || !std::strncmp(ss,"vminabs(",8) ||
                !std::strncmp(ss,"vmed(",5) || !std::strncmp(ss,"vkth(",5) ||
                !std::strncmp(ss,"vsum(",5) || !std::strncmp(ss,"vavg(",5) ||
                !std::strncmp(ss,"vstd(",5) || !std::strncmp(ss,"vvar(",5) ||
                !std::strncmp(ss,"vprod(",6) ||
                !std::strncmp(ss,"vargmin(",8) || !std::strncmp(ss,"vargmax(",8) ||
                !std::strncmp(ss,"vargminabs(",11) || !std::strncmp(ss,"vargmaxabs(",11) ||
                !std::strncmp(ss,"vargkth(",8)) { // Multi-argument vector functions
              _cimg_mp_op(ss[1]=='a'?(ss[2]=='v'?"Function 'vavg()'":
                                      ss[4]=='k'?"Function 'vargkth()'":
                                      ss[5]=='i' && ss[7]=='('?"Function 'vargmin()'":
                                      ss[5]=='i'?"Function vargminabs()'":
                                      ss[7]=='('?"Function 'vargmax()'":
                                      "Function 'vargmaxabs()'"):
                          ss[1]=='s'?(ss[2]=='u'?"Function 'vsum()'":"Function 'vstd()'"):
                          ss[1]=='k'?"Function 'vkth()'":
                          ss[1]=='p'?"Function 'vprod()'":
                          ss[1]=='v'?"Function 'vvar()'":
                          ss[2]=='i'?(ss[4]=='('?"Function 'vmin()'":
                                      "Function 'vminabs()'"):
                          ss[2]=='a'?(ss[4]=='('?"Function 'vmax()'":
                                      "Function 'vmaxabs()'"):
                          "Function 'vmed()'");
              op = ss[1]=='a'?(ss[2]=='v'?mp_vavg:
                               ss[4]=='k'?mp_vargkth:
                               ss[5]=='i' && ss[7]=='('?mp_vargmin:
                               ss[5]=='i'?mp_vargminabs:
                               ss[7]=='('?mp_vargmax:mp_vargmaxabs):
                ss[1]=='s'?(ss[2]=='u'?mp_vsum:mp_vstd):
                ss[1]=='k'?mp_vkth:
                ss[1]=='p'?mp_vprod:
                ss[1]=='v'?mp_vvar:
                ss[2]=='i'?(ss[4]=='('?mp_vmin:mp_vminabs):
                ss[2]=='a'?(ss[4]=='('?mp_vmax:mp_vmaxabs):
                mp_vmedian;
              CImg<ulongT>::vector((ulongT)op,0,0,0).move_to(l_opcode);
              p1 = ~0U;
              p3 = 1;
              for (s = std::strchr(ss,'(') + 1; s<se; ++s) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                p2 = size(arg2);
                if (p1==~0U) { if (is_vector(arg2)) p1 = p2; }
                else _cimg_mp_check_type(arg2,p3,3,p1);
                CImg<ulongT>::vector(arg2,p2).move_to(l_opcode);
                s = ns;
                ++p3;
              }
              (l_opcode>'y').move_to(opcode);
              if (p1==~0U) { pos = scalar(); p1 = 0; } else pos = vector(p1);
              opcode[1] = pos;
              opcode[2] = p1;
              opcode[3] = (opcode._height - 4)/2;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'w' :
            if (*ss1=='(') { // Image width
              _cimg_mp_op("Function 'w()'");
              if (*ss2=='#') { // Index specified
                p1 = compile(ss3,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss3);
                _cimg_mp_check_list();
              } else { if (ss2!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_width,p1);
            }

            if (!std::strncmp(ss,"warp(",5)) { // Image warping
              _cimg_mp_op("Function 'warp()'");
              pos = 1;
              for (s = ss5; s<se; ++s, ++pos) {
                ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                               (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                arg2 = compile(s,ns,depth1,0,block_flags);
                if (pos==1 || pos==6) _cimg_mp_check_type(arg2,pos,2,0);
                else if (pos<11) _cimg_mp_check_const_scalar(arg2,pos,3);
                else _cimg_mp_check_type(arg2,pos,1,0);
                CImg<ulongT>::vector(arg2).move_to(l_opcode);
                s = ns;
              }
              (l_opcode>'y').move_to(opcode);
              // opcode = [ A, wA,hA,dA,sA, B, wB,hB,dB,sB, mode, interp, boundary_cond ]
              //          [ 0   1  2  3  4  5   6  7  8  9    10      11             12 ]

              if (opcode.height()<10) compile(s,se1,depth1,0,block_flags); // Not enough arguments -> throw exception
              arg1 = (unsigned int)opcode[0]; // Image to warp
              arg2 = (unsigned int)opcode[5]; // Warp map
              p1 = size(arg1);
              p2 = size(arg2);
              p3 = opcode.height();
              opcode.resize(1,13,1,1,0);
              if (p3<11) opcode[10] = 0;
              if (p3<12) opcode[11] = 1;
              if (p3<13) opcode[12] = 0;
              arg3 = (unsigned int)mem[opcode[1]]; opcode[1] = arg3;
              arg4 = (unsigned int)mem[opcode[2]]; opcode[2] = arg4;
              arg5 = (unsigned int)mem[opcode[3]]; opcode[3] = arg5;
              arg6 = (unsigned int)mem[opcode[4]]; opcode[4] = arg6;
              if (arg3*arg4*arg5*arg6!=std::max(1U,p1)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Input vector size (%u values) and its specified "
                                            "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p1,1U),arg3,arg4,arg5,arg6,arg3*arg4*arg5*arg6);
              }
              arg3 = (unsigned int)mem[opcode[6]]; opcode[6] = arg3;
              arg4 = (unsigned int)mem[opcode[7]]; opcode[7] = arg4;
              arg5 = (unsigned int)mem[opcode[8]]; opcode[8] = arg5;
              arg6 = (unsigned int)mem[opcode[9]]; opcode[9] = arg6;
              if (arg3*arg4*arg5*arg6!=std::max(1U,p2)) {
                _cimg_mp_strerr;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: %s: Warp vector size (%u values) and its specified "
                                            "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                            pixel_type(),_cimg_mp_calling_function,s_op,
                                            std::max(p2,1U),arg3,arg4,arg5,arg6,arg3*arg4*arg5*arg6);
              }
              pos = vector(arg3*arg4*arg5*(unsigned int)opcode[4]);
              opcode.resize(1,15,1,1,0,0,0,1);
              opcode[0] = (ulongT)mp_warp;
              opcode[1] = (ulongT)pos;
              opcode.move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"wave(",5)) { // Wave function
              _cimg_mp_op("Function 'wave()'");
              s1 = ss5; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss5,s1,depth1,0,block_flags); // x
              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):4; // type
              _cimg_mp_check_type(arg2,2,1,0);
              if (is_vector(arg1)) _cimg_mp_vector2(wave,arg1,arg2);
              if (is_const_scalar(arg1) && is_const_scalar(arg2)) // Optimize constant case
                _cimg_mp_const_scalar(cimg::wave(mem[arg1],(unsigned int)mem[arg2]));
              _cimg_mp_scalar2(wave,arg1,arg2);
            }

            if (*ss1=='h' && *ss2=='(') { // Image width*height
              _cimg_mp_op("Function 'wh()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_wh,p1);
            }

            if (*ss1=='h' && *ss2=='d' && *ss3=='(') { // Image width*height*depth
              _cimg_mp_op("Function 'whd()'");
              if (*ss4=='#') { // Index specified
                p1 = compile(ss5,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss5);
                _cimg_mp_check_list();
              } else { if (ss4!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_whd,p1);
            }

            if (!std::strncmp(ss,"while(",6)) { // While...do
              _cimg_mp_op("Function 'while()'");
              s0 = *ss5=='('?ss6:ss8;
              s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              p1 = code._width;
              arg1 = compile(s0,s1,depth1,0,block_flags);
              p2 = code._width;
              arg6 = mempos;
              pos = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg1,1,1,0);
              arg2 = size(pos);
              CImg<ulongT>::vector((ulongT)mp_while,pos,arg1,p2 - p1,code._width - p2,arg2,
                                   pos>=arg6 && !is_const_scalar(pos),
                                   arg1>=arg6 && !is_const_scalar(arg1)).move_to(code,p1);
              _cimg_mp_return(pos);
            }

            if (*ss1=='h' && *ss2=='d' && *ss3=='s' && *ss4=='(') { // Image width*height*depth*spectrum
              _cimg_mp_op("Function 'whds()'");
              if (*ss5=='#') { // Index specified
                p1 = compile(ss6,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss6);
                _cimg_mp_check_list();
              } else { if (ss5!=se1) break; p1 = ~0U; }
              _cimg_mp_scalar1(image_whds,p1);
            }
            break;

          case 'x' :
            if (*ss1=='m' && *ss2=='(') { // Image x-coordinate of minimum value
              _cimg_mp_op("Function 'xm()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_xm,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='M' && *ss2=='(') { // Image x-coordinate of maximum value
              _cimg_mp_op("Function 'xM()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_xM,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (!std::strncmp(ss,"xor(",4)) { // Xor
              _cimg_mp_op("Function 'xor()'");
              s1 = ss4; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg1 = compile(ss4,s1,depth1,0,block_flags);
              arg2 = compile(++s1,se1,depth1,0,block_flags);
              _cimg_mp_check_type(arg2,2,3,size(arg1));
              if (is_vector(arg1) || is_vector(arg2)) _cimg_mp_vector2(bitwise_xor,arg1,arg2);
              if (is_const_scalar(arg1) && is_const_scalar(arg2))
                _cimg_mp_const_scalar((longT)mem[arg1] ^ (longT)mem[arg2]);
              _cimg_mp_scalar2(bitwise_xor,arg1,arg2);
            }
            break;

          case 'y' :
            if (*ss1=='m' && *ss2=='(') { // Image y-coordinate of minimum value
              _cimg_mp_op("Function 'ym()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_ym,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='M' && *ss2=='(') { // Image y-coordinate of maximum value
              _cimg_mp_op("Function 'yM()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_yM,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;

          case 'z' :
            if (*ss1=='m' && *ss2=='(') { // Image z-coordinate of minimum value
              _cimg_mp_op("Function 'zm()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_zm,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }

            if (*ss1=='M' && *ss2=='(') { // Image z-coordinate of maximum value
              _cimg_mp_op("Function 'zM()'");
              if (*ss3=='#') { // Index specified
                p1 = compile(ss4,se1,depth1,0,block_flags);
                _cimg_mp_check_notnan_index(p1,ss4);
                _cimg_mp_check_list();
              } else { if (ss3!=se1) break; p1 = ~0U; }
              pos = scalar();
              CImg<ulongT>::vector((ulongT)mp_image_stats_zM,pos,p1).move_to(code);
              return_comp = true;
              _cimg_mp_return(pos);
            }
            break;
          }

          if (!std::strncmp(ss,"fft(",4) || !std::strncmp(ss,"ifft(",5)) { // FFT and iFFT
            is_sth = *ss=='i'; // is_ifft ?
            _cimg_mp_op(is_sth?"Function 'ifft()'":"Function 'fft()'");
            s0 = is_sth?ss5:ss4;
            s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
            arg1 = compile(s0,s1,depth1,0,block_flags); // Real part
            p1 = size(arg1);
            s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
            arg2 = compile(s1,s2,depth1,0,block_flags); // Imaginary part
            arg3 = ~0U; arg4 = arg5 = arg6 = 1; p3 = 0;
            if (s2<se1) {
              s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
              arg3 = compile(s2,s1,depth1,0,block_flags); // Width
              if (s1<se1) {
                s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                arg4 = compile(s1,s2,depth1,0,block_flags); // Height
                if (s2<se1) {
                  s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                  arg5 = compile(s2,s1,depth1,0,block_flags); // Depth
                  if (s1<se1) {
                    s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
                    arg6 = compile(s1,s2,depth1,0,block_flags); // Spectrum
                    p3 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0; // Axes
                  }
                }
              }
            }
            if (arg3!=~0U) {
              _cimg_mp_check_const_scalar(3,arg3,3);
              _cimg_mp_check_const_scalar(4,arg4,3);
              _cimg_mp_check_const_scalar(5,arg5,3);
              _cimg_mp_check_const_scalar(6,arg6,3);
              arg3 = (unsigned int)mem[arg3];
              arg4 = (unsigned int)mem[arg4];
              arg5 = (unsigned int)mem[arg5];
              arg6 = (unsigned int)mem[arg6];
            } else arg3 = p1;
            p2 = arg3*arg4*arg5*arg6;
            if (p1!=p2) {
              _cimg_mp_strerr;
              throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                          "CImg<%s>::%s: %s: Vector size (%u values) and its specified "
                                          "geometry (%u,%u,%u,%u) (%u values) do not match.",
                                          pixel_type(),_cimg_mp_calling_function,s_op,
                                          std::max(p1,1U),arg3,arg4,arg5,arg6,p2);
            }
            _cimg_mp_check_type(arg1,1,2,p2);
            _cimg_mp_check_type(arg2,2,2,p2);
            CImg<ulongT>::vector((ulongT)mp_fft,_cimg_mp_slot_nan,is_sth,arg1,arg2,arg3,arg4,arg5,arg6,p3,size(p3)).
              move_to(code);
            _cimg_mp_return_nan();
          }

          if ((!std::strncmp(ss,"norm",4) && ss4<se1 && (s = std::strchr(ss4,'('))!=0) || // Lp norm (constant p)
              (!std::strncmp(ss,"hypot(",6) && (s = ss5))) {
            const bool is_hypot = *ss=='h';
            _cimg_mp_op(is_hypot?"Function 'hypot()'":"Function 'norm()'");
            arg1 = !is_hypot && s!=ss4?compile(ss4,s,depth1,0,block_flags):2;
            _cimg_mp_check_const_scalar(arg1,0,0);
            val = mem[arg1];
            is_sth = true; // Indicates that all arguments are constant
            CImg<ulongT>::vector(0,0,0,arg1).move_to(l_opcode);
            for (++s; s<se; ++s) {
              ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                             (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
              arg2 = compile(s,ns,depth1,0,block_flags);
              if (is_vector(arg2))
                CImg<ulongT>::sequence(size(arg2),arg2 + 1,arg2 + (ulongT)size(arg2)).move_to(l_opcode);
              else
                CImg<ulongT>::vector(arg2).move_to(l_opcode);
              is_sth&=is_const_scalar(arg2);
              s = ns;
            }
            (l_opcode>'y').move_to(opcode);
            op = val==2?(is_hypot && opcode._height<8?mp_vector_hypot:mp_vector_norm2):
              val==1?mp_vector_norm1:!val?mp_vector_norm0:
              cimg::type<double>::is_inf(val)?mp_vector_norminf:mp_normp;
            opcode[0] = (ulongT)op;
            opcode[2] = opcode._height;
            if (is_sth) _cimg_mp_const_scalar(op(*this));
            if (opcode._height==5) { // Single argument
              if (arg1) { _cimg_mp_scalar1(abs,opcode[4]); } else { _cimg_mp_scalar2(neq,opcode[4],0); }
            }
            opcode[1] = pos = scalar();
            opcode.move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          }

          if ((*ss=='u' || *ss=='v') && *ss1=='(') { // Random value with uniform distribution in specified range
            is_sth = *ss=='v'; // is integer generator?
            _cimg_mp_op(is_sth?"Function 'v()'":"Function 'u()'");
            if (*ss2==')') _cimg_mp_return(scalar0(is_sth?mp_rand_int_0_1:mp_rand_double_0_1));
            s1 = ss2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
            arg1 = compile(ss2,s1,depth1,0,block_flags);
            arg3 = arg4 = 1;
            if (s1<se1) {
              s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;
              arg2 = compile(s1,s2,depth1,0,block_flags);
              if (s2<se1) {
                s1 = ++s2; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
                arg3 = compile(s2,s1,depth1,0,block_flags);
                arg4 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
              }
            } else { arg2 = arg1; arg1 = 0; }
            _cimg_mp_check_type(arg2,2,3,size(arg1));
            _cimg_mp_check_type(arg3,3,1,0);
            _cimg_mp_check_type(arg4,4,1,0);
            if (arg3==1 && arg4==1) { // Fastest version (closed set)
              if (is_vector(arg1) || is_vector(arg2)) {
                if (is_sth) { _cimg_mp_vector2(rand_int,arg1,arg2); }
                else { _cimg_mp_vector2(rand_double,arg1,arg2); }
              }
              if (arg1==arg2) _cimg_mp_same(arg1);
              if (arg2==1) {
                if (!arg1) _cimg_mp_return(scalar0(is_sth?mp_rand_int_0_1:mp_rand_double_0_1));
                if (arg1==11) _cimg_mp_return(scalar0(is_sth?mp_rand_int_m1_1:mp_rand_double_m1_1));
              } else if (!arg1) _cimg_mp_return(scalar1(is_sth?mp_rand_int_0_N:mp_rand_double_0_N,arg2));
              _cimg_mp_return(scalar2(is_sth?mp_rand_int:mp_rand_double,arg1,arg2));
            } else { // Slower version (potentially an open set)
              if (is_vector(arg1) || is_vector(arg2)) {
                op = is_sth?mp_vector_rand_int_ext:mp_vector_rand_double_ext;
                p1 = size(arg1); p2 = size(arg2); p3 = std::max(p1,p2);
                if (p3) pos = vector(p3); else pos = scalar();
                CImg<ulongT>::vector((ulongT)op,pos,arg1,p1,arg2,p2,arg3,arg4).move_to(code);
                return_comp = true;
                _cimg_mp_return(pos);
              }
              op = is_sth?mp_rand_int_ext:mp_rand_double_ext;
              _cimg_mp_return(scalar4(op,arg1,arg2,arg3,arg4));
            }
          }

          if (!std::strncmp(ss,"argkth(",7) || !std::strncmp(ss,"avg(",4) ||
              !std::strncmp(ss,"argmax(",7) || !std::strncmp(ss,"argmaxabs(",10) ||
              !std::strncmp(ss,"argmin(",7) || !std::strncmp(ss,"argminabs(",10) ||
              !std::strncmp(ss,"gcd(",4) || !std::strncmp(ss,"kth(",4) || !std::strncmp(ss,"lcm(",4) ||
              !std::strncmp(ss,"max(",4) || !std::strncmp(ss,"maxabs(",7) || !std::strncmp(ss,"med(",4) ||
              !std::strncmp(ss,"min(",4) || !std::strncmp(ss,"minabs(",7) || !std::strncmp(ss,"prod(",5) ||
              !std::strncmp(ss,"std(",4) || !std::strncmp(ss,"sum(",4) || !std::strncmp(ss,"var(",4)
              ) { // Multi-argument functions
            _cimg_mp_op(*ss=='a'?(ss[3]=='k'?"Function 'argkth()'":
                                  ss[1]=='v'?"Function 'avg()'":
                                  ss[4]=='a'?(ss[6]=='('?"Function 'argmax()'":"Function 'argmaxabs()'"):
                                  ss[6]=='('?"Function 'argmin()'":"Function 'argminabs()'"):
                        *ss=='g'?"Function 'gcd()'":
                        *ss=='k'?"Function 'kth()'":
                        *ss=='l'?"Function 'lcm()'":
                        *ss=='m'?(ss[1]=='a'?(ss[3]=='('?"Function 'max()'":"Function 'maxabs()'"):
                                  ss[1]=='e'?"Function 'med()'":
                                  ss[3]=='('?"Function 'min()'":"Function 'minabs()'"):
                        *ss=='p'?"Function 'prod()'":
                        *ss=='s'?(ss[1]=='t'?"Function 'std()'":"Function 'sum()'"):
                        "Function 'var()'");

            op = *ss=='a'?(ss[3]=='k'?mp_argkth:
                           ss[1]=='v'?mp_avg:
                           ss[4]=='a'?(ss[6]=='('?mp_argmax:mp_argmaxabs):
                           ss[6]=='('?mp_argmin:mp_argminabs):
              *ss=='g'?mp_gcd:
              *ss=='k'?mp_kth:
              *ss=='l'?mp_lcm:
              *ss=='m'?(ss[1]=='a'?(ss[3]=='('?mp_max:mp_maxabs):
                        ss[1]=='e'?mp_med:
                        ss[3]=='('?mp_min:mp_minabs):
              *ss=='p'?mp_prod:
              *ss=='s'?(ss[1]=='t'?mp_std:mp_sum):
              mp_var;

            is_sth = true; // Indicates that all arguments are constant
            bool is_scalar = true; // Indicates that all arguments are scalars
            CImg<ulongT>::vector((ulongT)op,0,0).move_to(l_opcode);

            for (s = std::strchr(ss,'(') + 1; s<se; ++s) {
              ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                             (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
              arg2 = compile(s,ns,depth1,0,block_flags);
              if (is_vector(arg2)) {
                CImg<ulongT>::vector(arg2 + 1,size(arg2)).move_to(l_opcode);
                is_scalar = false;
              } else CImg<ulongT>::vector(arg2,1).move_to(l_opcode);
              is_sth&=is_const_scalar(arg2);
              s = ns;
            }
            (l_opcode>'y').move_to(opcode);
            opcode[2] = opcode._height;

            if (is_scalar && opcode[2]==5) { // Special optimizable case 'fn(a)'
              if (op==mp_avg || op==mp_gcd || op==mp_lcm || op==mp_max || op==mp_maxabs ||
                  op==mp_med || op==mp_min || op==mp_minabs || op==mp_prod || op==mp_sum)
                _cimg_mp_same(arg2);
              if (op==mp_argmax || op==mp_argmaxabs || op==mp_argmin || op==mp_argminabs)
                _cimg_mp_return(0);
            }
            if (is_scalar && opcode[2]==7) { // Special optimizable case 'fn(a,b)'
#define _cimg_mp_func_2args(fn) if (op==mp_##fn) { \
  if (is_sth) { opcode[2] = opcode[3]; opcode[3] = opcode[5]; _cimg_mp_const_scalar(mp_##fn##2(*this)); } \
                _cimg_mp_scalar2(fn##2,opcode[3],opcode[5]); }
              if (op==mp_kth) _cimg_mp_same(arg2);
              if (op==mp_argkth) _cimg_mp_return(1);
              _cimg_mp_func_2args(avg); _cimg_mp_func_2args(argmax); _cimg_mp_func_2args(argmaxabs);
              _cimg_mp_func_2args(argmin); _cimg_mp_func_2args(argminabs); _cimg_mp_func_2args(gcd);
              _cimg_mp_func_2args(lcm); _cimg_mp_func_2args(max); _cimg_mp_func_2args(maxabs);
              _cimg_mp_func_2args(med); _cimg_mp_func_2args(min); _cimg_mp_func_2args(minabs);
              _cimg_mp_func_2args(prod); _cimg_mp_func_2args(std); _cimg_mp_func_2args(sum); _cimg_mp_func_2args(var);
            }
            if (is_sth) _cimg_mp_const_scalar(op(*this));
            pos = opcode[1] = scalar();
            opcode.move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          }

          // No corresponding built-in function -> Look for a user-defined macro call.
          s0 = strchr(ss,'(');
          if (s0) {
            variable_name.assign(ss,(unsigned int)(s0 - ss + 1)).back() = 0;

            // Count number of specified arguments.
            p1 = 0;
            for (s = s0 + 1; s<=se1; ++p1, s = ns + 1) {
              while (*s && cimg::is_blank(*s)) ++s;
              if (*s==')' && !p1) break;
              ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                             (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
            }

            char mb = 0;
            arg3 = 0; // Number of possible name matches
            cimglist_for(macro_def,l) if (!std::strcmp(macro_def[l],variable_name) && ++arg3 &&
                                          ((mb = macro_def[l].back())==(char)p1 || mb==(char)-1)) {
              const bool is_variadic = mb==(char)-1;
              p2 = is_variadic?1U:(unsigned int)mb; // Number of required arguments
              CImg<charT> _expr = macro_body[l]; // Expression to be substituted

              p1 = 1; // Index of current parsed argument
              for (s = s0 + 1; s<=se1; ++p1, s = ns + 1) { // Parse function arguments
                while (*s && cimg::is_blank(*s)) ++s;
                if (!is_variadic && *s==')' && p1==1) break; // Function has no arguments
                if (p1>p2) { ++p1; break; }

                if (is_variadic) ns = se1;
                else {
                  ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                                 (*ns!=')' || level[ns - expr._data]!=clevel)) ++ns;
                }
                variable_name.assign(s,(unsigned int)(ns - s + 1)).back() = 0; // Argument to write

                arg2 = 0;
                cimg_forX(_expr,k) {
                  if (_expr[k]==(char)p1) { // Perform argument substitution
                    arg1 = _expr._width;
                    if (variable_name._width>1) {
                      _expr.resize(arg1 + variable_name._width - 2,1,1,1,0);
                      std::memmove(_expr._data + k + variable_name._width - 1,_expr._data + k + 1,arg1 - k - 1);
                      std::memcpy(_expr._data + k,variable_name,variable_name._width - 1);
                      k+=variable_name._width - 2;
                    } else {
                      std::memmove(_expr._data + k,_expr._data + k + 1,arg1 - k - 1);
                      --k;
                    }
                  }
                  ++arg2;
                }
              }

              // Recompute 'pexpr' and 'level' for evaluating substituted expression.
              CImg<charT> _pexpr(_expr._width);
              ns = _pexpr._data;
              for (ps = _expr._data, c1 = ' '; *ps; ++ps) {
                if (!cimg::is_blank(*ps)) c1 = *ps;
                *(ns++) = c1;
              }
              *ns = 0;

              CImg<uintT> _level = get_level(_expr);
              expr.swap(_expr);
              pexpr.swap(_pexpr);
              level.swap(_level);
              s0 = user_macro;
              user_macro = macro_def[l];
              pos = compile(expr._data,expr._data + expr._width - 1,depth1,p_ref,block_flags);
              user_macro = s0;
              level.swap(_level);
              pexpr.swap(_pexpr);
              expr.swap(_expr);
              _cimg_mp_return(pos);
            }

            if (arg3) { // Macro name matched but number of arguments does not
              CImg<uintT> sig_nargs(arg3);
              arg1 = 0;
              cimglist_for(macro_def,l) if (!std::strcmp(macro_def[l],variable_name))
                sig_nargs[arg1++] = (unsigned int)macro_def[l].back();
              _cimg_mp_strerr;
              cimg::strellipsize(variable_name,64);
              if (sig_nargs._width>1) {
                sig_nargs.sort();
                arg1 = sig_nargs.back();
                --sig_nargs._width;
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: Function '%s()': Number of specified arguments (%u) "
                                            "does not match macro declaration (defined for %s or %u arguments), "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,variable_name._data,
                                            p1,sig_nargs.value_string()._data,arg1,s0);
              } else {
                throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                            "CImg<%s>::%s: Function '%s()': Number of specified arguments (%u) "
                                            "does not match macro declaration (defined for %u argument%s), "
                                            "in expression '%s'.",
                                            pixel_type(),_cimg_mp_calling_function,variable_name._data,
                                            p1,*sig_nargs,*sig_nargs!=1?"s":"",s0);
              }
            }
          }
        } // if (se1==')')

        // Char / string initializer.
        if (*se1=='\'' &&
            ((se1>ss && *ss=='\'') ||
             (se1>ss1 && *ss=='_' && *ss1=='\''))) {
          if (*ss=='_') { _cimg_mp_op("Char initializer"); s1 = ss2; }
          else { _cimg_mp_op("String initializer"); s1 = ss1; }
          arg1 = (unsigned int)(se1 - s1); // Original string length
          if (arg1) {
            CImg<charT>(s1,arg1 + 1).move_to(variable_name).back() = 0;
            cimg::strunescape(variable_name);
            arg1 = (unsigned int)std::strlen(variable_name);
          }
          if (!arg1) _cimg_mp_return(0); // Empty string -> 0
          if (*ss=='_') {
            if (arg1==1) _cimg_mp_const_scalar((unsigned char)*variable_name);
            cimg::strellipsize(variable_name,64);
            _cimg_mp_strerr;
            throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                        "CImg<%s>::%s: %s: Literal %s contains more than one byte, "
                                        "in expression '%s'.",
                                        pixel_type(),_cimg_mp_calling_function,s_op,
                                        ss1,s0);
          }
          pos = vector(arg1);
          CImg<ulongT>::vector((ulongT)mp_string_init,pos,arg1).move_to(l_opcode);
          CImg<ulongT>(1,arg1/sizeof(ulongT) + (arg1%sizeof(ulongT)?1:0)).move_to(l_opcode);
          std::memcpy((char*)l_opcode[1]._data,variable_name,arg1);
          (l_opcode>'y').move_to(is_inside_begin || is_new_variable_assignment?code:code_begin);
          return_comp = is_new_variable_assignment;
          if (!return_comp) set_reserved_vector(pos); // Prevent from being used in further optimization
          _cimg_mp_return(pos);
        }

        // Vector initializer [ ... ].
        if (*ss=='[' && *se1==']') {
          _cimg_mp_op("Vector initializer");
          s1 = ss1; while (s1<se2 && cimg::is_blank(*s1)) ++s1;
          s2 = se2; while (s2>s1 && cimg::is_blank(*s2)) --s2;
          if (s2>s1 && *s1=='\'' && *s2=='\'') { // Vector values provided as a string
            arg1 = (unsigned int)(s2 - s1 - 1); // Original string length
            if (arg1) {
              CImg<charT>(s1 + 1,arg1 + 1).move_to(variable_name).back() = 0;
              cimg::strunescape(variable_name);
              arg1 = (unsigned int)std::strlen(variable_name);
            }
            if (!arg1) _cimg_mp_return(0); // Empty string -> 0
            pos = vector(arg1);
            CImg<ulongT>::vector((ulongT)mp_string_init,pos,arg1).move_to(l_opcode);
            CImg<ulongT>(1,arg1/sizeof(ulongT) + (arg1%sizeof(ulongT)?1:0)).move_to(l_opcode);
            std::memcpy((char*)l_opcode[1]._data,variable_name,arg1);
            (l_opcode>'y').move_to(is_inside_begin || is_new_variable_assignment?code:code_begin);
            return_comp = is_new_variable_assignment;
            if (!return_comp) set_reserved_vector(pos); // Prevent from being used in further optimization
          } else { // Vector values provided as a list of items
            is_sth = !is_new_variable_assignment; // Can vector be defined once in 'begin()'?
            arg3 = 0; // Output vector size
            CImg<ulongT>::vector((ulongT)mp_vector_init,0,0,0).move_to(l_opcode);
            s = ss1; while (*s && cimg::is_blank(*s)) ++s;
            if (s>=se1) _cimg_mp_return(0); // Empty initializer
            for (; s<se; ++s) {
              ns = s; while (ns<se && (*ns!=',' || level[ns - expr._data]!=clevel1) &&
                             (*ns!=']' || level[ns - expr._data]!=clevel)) ++ns;
              const CImgList<ulongT> &rcode = is_inside_begin?code:code_begin;
              p1 = rcode.size();
              p2 = variable_def.size();
              arg1 = compile(s,ns,depth1,0,block_flags);
              p3 = rcode.size();
              if (is_vector(arg1)) {
                arg2 = size(arg1);
                arg3+=arg2;
                CImg<ulongT>::vector(arg1,arg2).move_to(l_opcode);
                const CImg<ulongT> &rcode_back = rcode.back();
                is_sth&=p3>p1 && rcode_back[1]==arg1 &&
                  (rcode_back[0]==(ulongT)mp_string_init ||
                   rcode_back[0]==(ulongT)mp_vector_init) && variable_def.size()==p2 && !is_comp_vector(arg1);
                // ^^ Tricky part: detect if 'arg1' is a newly constructed vector not assigned to a variable
                // (i.e. a vector-valued literal).
              } else {
                ++arg3;
                CImg<ulongT>::vector(arg1,0).move_to(l_opcode);
                is_sth&=is_const_scalar(arg1);
              }
              s = ns;
            }

            if (l_opcode.size()==2 && is_vector(arg1)) _cimg_mp_return(arg1); // Special case: '[ [ item(s) ] ]'
            pos = vector(arg3);
            (l_opcode>'y').move_to(opcode);
            opcode[1] = pos;
            opcode[2]=  arg3;
            opcode[3] = (opcode._height - 4)/2;
            opcode.move_to(!is_sth || is_inside_begin || is_new_variable_assignment?code:code_begin);
            return_comp = !is_sth && is_new_variable_assignment;
            if (!return_comp) set_reserved_vector(pos); // Prevent from being used in further optimization
          }
          _cimg_mp_return(pos);
        }

        // Variables related to the input list of images.
        if (*ss1=='#' && ss2<se) {
          arg1 = compile(ss2,se,depth1,0,block_flags);
          _cimg_mp_check_notnan_index(arg1,ss2);
          p1 = (unsigned int)(imglist._width && is_const_scalar(arg1)?
                              cimg::mod((int)mem[arg1],imglist.width()):~0U);
          switch (*ss) {
          case 'w' : // w#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._width);
            _cimg_mp_scalar1(image_width,arg1);
          case 'h' : // h#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._height);
            _cimg_mp_scalar1(image_height,arg1);
          case 'd' : // d#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._depth);
            _cimg_mp_scalar1(image_depth,arg1);
          case 'r' : // r#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._is_shared);
            _cimg_mp_scalar1(image_is_shared,arg1);
          case 's' : // s#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._spectrum);
            _cimg_mp_scalar1(image_spectrum,arg1);
          case 'i' : // i#ind
            if (!imglist) _cimg_mp_return(0);
            _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,_cimg_mp_slot_c,
                             0,_cimg_mp_boundary);
          case 'I' : // I#ind
            p2 = p1!=~0U?imglist[p1]._spectrum:imglist._width?~0U:0;
            if (!p2) _cimg_mp_return(0);
            pos = vector(p2);
            CImg<ulongT>::vector((ulongT)mp_IJoff,pos,1,p1,0,0,p2).move_to(code);
            return_comp = true;
            _cimg_mp_return(pos);
          case 'R' : // R#ind
            if (!imglist) _cimg_mp_return(0);
            _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,0,
                             0,_cimg_mp_boundary);
          case 'G' : // G#ind
            if (!imglist) _cimg_mp_return(0);
            _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,1,
                             0,_cimg_mp_boundary);
          case 'B' : // B#ind
            if (!imglist) _cimg_mp_return(0);
            _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,2,
                             0,_cimg_mp_boundary);
          case 'A' : // A#ind
            if (!imglist) _cimg_mp_return(0);
            _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,3,
                             0,_cimg_mp_boundary);
          }
        }

        if (*ss1 && *ss2=='#' && ss3<se) {
          arg1 = compile(ss3,se,depth1,0,block_flags);
          _cimg_mp_check_notnan_index(arg1,ss3);
          p1 = (unsigned int)(imglist._width && is_const_scalar(arg1)?
                              cimg::mod((int)mem[arg1],imglist.width()):~0U);
          if (*ss=='w' && *ss1=='h') { // wh#ind
            if (!imglist) _cimg_mp_return(0);
            if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._width*imglist[p1]._height);
            _cimg_mp_scalar1(image_wh,arg1);
          }
          arg2 = ~0U;

          if (*ss=='i') {
            if (*ss1>='0' && *ss1<='9') { // i0#ind...i9#ind
              if (!imglist) _cimg_mp_return(0);
              _cimg_mp_scalar8(ijxyzc1,0,arg1,_cimg_mp_slot_x,_cimg_mp_slot_y,_cimg_mp_slot_z,*ss1 - '0',
                               0,_cimg_mp_boundary);
            }

            if (*ss1=='c') { // ic#ind
              if (!imglist) _cimg_mp_return(0);
              if (is_const_scalar(arg1)) {
                if (!list_median) list_median.assign(imglist._width);
                if (!list_median[p1]) CImg<doubleT>::vector(imglist[p1].median()).move_to(list_median[p1]);
                _cimg_mp_const_scalar(*list_median[p1]);
              }
              _cimg_mp_scalar1(image_stats_ic_static,arg1);
            }

            if (*ss1=='d') { // id#ind
              if (!imglist) _cimg_mp_return(0);
              if (is_const_scalar(arg1)) {
                if (!list_stats) list_stats.assign(imglist._width);
                if (!list_stats[p1]) list_stats[p1].assign(1,15,1,1,0).fill(imglist[p1].get_stats(),false);
                _cimg_mp_const_scalar(std::sqrt(list_stats(p1,3)));
              }
              _cimg_mp_scalar1(image_stats_id_static,arg1);
            }

            switch (*ss1) {
            case 'a' : arg2 = 2; break; // ia#ind
            case 'm' : arg2 = 0; break; // im#ind
            case 'M' : arg2 = 1; break; // iM#ind
            case 'n' : arg2 = 14; break; // in#ind
            case 'p' : arg2 = 13; break; // ip#ind
            case 's' : arg2 = 12; break; // is#ind
            case 'v' : arg2 = 3; break; // iv#ind
            }
          } else if (*ss1=='m') switch (*ss) {
            case 'x' : arg2 = 4; break; // xm#ind
            case 'y' : arg2 = 5; break; // ym#ind
            case 'z' : arg2 = 6; break; // zm#ind
            case 'c' : arg2 = 7; break; // cm#ind
            } else if (*ss1=='M') switch (*ss) {
            case 'x' : arg2 = 8; break; // xM#ind
            case 'y' : arg2 = 9; break; // yM#ind
            case 'z' : arg2 = 10; break; // zM#ind
            case 'c' : arg2 = 11; break; // cM#ind
            }
          if (arg2!=~0U) {
            if (!imglist) _cimg_mp_return(0);
            if (is_const_scalar(arg1)) {
              if (!list_stats) list_stats.assign(imglist._width);
              if (!list_stats[p1]) list_stats[p1].assign(1,15,1,1,0).fill(imglist[p1].get_stats(),false);
              _cimg_mp_const_scalar(list_stats(p1,arg2));
            }
            _cimg_mp_scalar2(image_stats_static,arg1,arg2);
          }
        }

        if (*ss=='w' && *ss1=='h' && *ss2=='d' && *ss3=='#' && ss4<se) { // whd#ind
          arg1 = compile(ss4,se,depth1,0,block_flags);
          _cimg_mp_check_notnan_index(arg1,ss4);
          if (!imglist) _cimg_mp_return(0);
          p1 = (unsigned int)(is_const_scalar(arg1)?cimg::mod((int)mem[arg1],imglist.width()):~0U);
          if (p1!=~0U) _cimg_mp_const_scalar(imglist[p1]._width*imglist[p1]._height*imglist[p1]._depth);
          _cimg_mp_scalar1(image_whd,arg1);
        }
        if (*ss=='w' && *ss1=='h' && *ss2=='d' && *ss3=='s' && *ss4=='#' && ss5<se) { // whds#ind
          arg1 = compile(ss5,se,depth1,0,block_flags);
          _cimg_mp_check_notnan_index(arg1,ss5);
          if (!imglist) _cimg_mp_return(0);
          p1 = (unsigned int)(is_const_scalar(arg1)?cimg::mod((int)mem[arg1],imglist.width()):~0U);
          if (p1!=~0U)
            _cimg_mp_const_scalar(imglist[p1]._width*imglist[p1]._height*imglist[p1]._depth*imglist[p1]._spectrum);
          _cimg_mp_scalar1(image_whds,arg1);
        }

        if (!std::strcmp(ss,"interpolation")) _cimg_mp_return(_cimg_mp_interpolation); // interpolation
        if (!std::strcmp(ss,"boundary")) _cimg_mp_return(_cimg_mp_boundary); // boundary

        variable_name.assign(ss,(unsigned int)(se + 1 - ss)).back() = 0;

#ifdef cimg_mp_operator_dollar
        if (*ss=='$' && ss1<se) // External variable '$varname'
          _cimg_mp_const_scalar(cimg_mp_operator_dollar(variable_name._data + 1));
#endif

        // No known item found, assuming this is an already initialized variable.
        if (cimg::is_varname(variable_name)) { // Valid variable name
          get_variable_pos(variable_name,arg1,arg2);
          arg1 = arg2!=~0U?reserved_label[arg2]:arg1!=~0U?variable_pos[arg1]:~0U;
          if (arg1!=~0U) _cimg_mp_return(arg1);
        }

        // Reached an unknown item -> error.
        c1 = *se1;
        cimg::strellipsize(variable_name,64);
        _cimg_mp_strerr;
        if (is_sth)
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: Undefined variable '%s' in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,
                                      variable_name._data,s0);
        s1 = std::strchr(ss,'(');
        s_op = s1 && c1==')'?"function call":"item";
        throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                    "CImg<%s>::%s: Unrecognized %s '%s' in expression '%s'.",
                                    pixel_type(),_cimg_mp_calling_function,
                                    s_op,variable_name._data,s0);
      }

      // Evaluate a portion of the compiled expression.
      void eval(const CImg<ulongT> *const p_begin, const CImg<ulongT> *const p_end) {
        for (p_code = p_begin; p_code<p_end; ++p_code) {
          opcode._data = p_code->_data;
          const ulongT func = opcode[0], target = opcode[1];
          mem[target] = (*(mp_func)func)(*this);
        }
      }

      // Evaluate expression for a given set of (x,y,z,c) coordinates (return scalar value).
      double operator()(const double x, const double y, const double z, const double c) {
        mem[_cimg_mp_slot_x] = x; mem[_cimg_mp_slot_y] = y; mem[_cimg_mp_slot_z] = z; mem[_cimg_mp_slot_c] = c;
        eval(code,p_code_end);
        return *result;
      }

      // Evaluate expression for a given set of (x,y,z,c) coordinates (return output values in vector 'output').
      template<typename t>
      void operator()(const double x, const double y, const double z, const double c, t *const output) {
        mem[_cimg_mp_slot_x] = x; mem[_cimg_mp_slot_y] = y; mem[_cimg_mp_slot_z] = z; mem[_cimg_mp_slot_c] = c;
        eval(code,p_code_end);
        if (result_dim) {
          const double *ptrs = result + 1;
          t *ptrd = output;
          for (unsigned int k = 0; k<result_dim; ++k) *(ptrd++) = (t)*(ptrs++);
        } else *output = (t)*result;
      }

      // Evaluate begin() block.
      void begin() {
        if (!code_begin) return;
        mem[_cimg_mp_slot_x] = mem[_cimg_mp_slot_y] = mem[_cimg_mp_slot_z] = mem[_cimg_mp_slot_c] = 0;
        eval(code_begin,code_begin.end());
      }

      // Evaluate begin_t() block.
      void begin_t() {
        if (!code_begin_t) return;
        mem[_cimg_mp_slot_x] = mem[_cimg_mp_slot_y] = mem[_cimg_mp_slot_z] = mem[_cimg_mp_slot_c] = 0;
        eval(code_begin_t,code_begin_t.end());
      }

      // Evaluate end_t() block.
      void end_t() {
        if (!code_end_t) return;
        if (imgin) {
          mem[_cimg_mp_slot_x] = imgin._width - 1.;
          mem[_cimg_mp_slot_y] = imgin._height - 1.;
          mem[_cimg_mp_slot_z] = imgin._depth - 1.;
          mem[_cimg_mp_slot_c] = imgin._spectrum - 1.;
        } else mem[_cimg_mp_slot_x] = mem[_cimg_mp_slot_y] = mem[_cimg_mp_slot_z] = mem[_cimg_mp_slot_c] = 0;
        eval(code_end_t,code_end_t.end());
      }

      // Evaluate end() block.
      void end() {
        if (!code_end) return;
        if (imgin) {
          mem[_cimg_mp_slot_x] = imgin._width - 1.;
          mem[_cimg_mp_slot_y] = imgin._height - 1.;
          mem[_cimg_mp_slot_z] = imgin._depth - 1.;
          mem[_cimg_mp_slot_c] = imgin._spectrum - 1.;
        } else mem[_cimg_mp_slot_x] = mem[_cimg_mp_slot_y] = mem[_cimg_mp_slot_z] = mem[_cimg_mp_slot_c] = 0;
        eval(code_end,code_end.end());
      }

      // Merge inter-thread variables.
      // (argument 'mp' is the master instance).
      void merge(_cimg_math_parser& mp) {
        if (&mp==this) return;
        cimg_rofY(mp.memmerge,k) {
          const unsigned int
            pos = (unsigned int)mp.memmerge(0,k),
            siz = (unsigned int)mp.memmerge(1,k),
            iop = (unsigned int)mp.memmerge(2,k);
          if (!siz) switch (iop) { // Scalar value
            case 0 : mp.mem[pos] = mem[pos]; break; // Assignment
            case 1 : mp.mem[pos]+=mem[pos]; break; // Operator+
            case 2 : mp.mem[pos]-=mem[pos]; break; // Operator-
            case 3 : mp.mem[pos]*=mem[pos]; break; // Operator*
            case 4 : mp.mem[pos]/=mem[pos]; break; // Operator/
            case 5 : mp.mem[pos] = (double)((longT)mp.mem[pos] & (longT)mem[pos]); break; // Operator&
            case 6 : mp.mem[pos] = (double)((longT)mp.mem[pos] | (longT)mem[pos]); break; // Operator|
            case 7 : mp.mem[pos] = (double)((longT)mp.mem[pos] ^ (longT)mem[pos]); break; // Operator 'xor'
            case 8 : mp.mem[pos] = mp.mem[pos] && mem[pos]; break; // Operator&&
            case 9 : mp.mem[pos] = mp.mem[pos] || mem[pos]; break; // Operator||
            case 10 : mp.mem[pos] = std::min(mp.mem[pos],mem[pos]); break; // Operator 'min'
            case 11 : mp.mem[pos] = std::max(mp.mem[pos],mem[pos]); break; // Operator 'max'
            } else switch (iop) { // Vector value
            case 0 : // Assignment
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true) = CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 1 : // Operator+
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true)+=CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 2 : // Operator-
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true)-=CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 3 : // Operator*
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true).mul(CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true));
              break;
            case 4 : // Operator/
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true).div(CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true));
              break;
            case 5 : // Operator&
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true)&=CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 6 : // Operator|
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true)|=CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 7 : // Operator 'xor'
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true)^=CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true);
              break;
            case 8 : { // Operator&&
              CImg<doubleT>
                arg1(&mp.mem[pos + 1],siz,1,1,1,true),
                arg2(&mem[pos + 1],siz,1,1,1,true);
              cimg_foroff(arg1,off) arg1[off] = arg1[off] && arg2[off];
            } break;
            case 9 : { // Operator||
              CImg<doubleT>
                arg1(&mp.mem[pos + 1],siz,1,1,1,true),
                arg2(&mem[pos + 1],siz,1,1,1,true);
              cimg_foroff(arg1,off) arg1[off] = arg1[off] || arg2[off];
            } break;
            case 10 : // Operator 'min'
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true).min(CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true));
              break;
            case 11 : // Operator 'max'
              CImg<doubleT>(&mp.mem[pos + 1],siz,1,1,1,true).max(CImg<doubleT>(&mem[pos + 1],siz,1,1,1,true));
              break;
            }
        }
      }

      // Return specified argument number as a string.
      static const char *s_argth(const unsigned int n_arg) {
        const char
          *_s_arg[] = { "", "First", "Second", "Third", "Fourth", "Fifth", "Sixth", "Seventh", "Eighth","Ninth",
          "10th", "11th", "12th", "13th", "14th", "15th", "16th", "17th", "18th", "19th",
          "20th", "21st", "22nd", "23rd", "24th", "25th", "26th", "27th", "28th", "One of the" };
        return _s_arg[n_arg<sizeof(_s_arg)/sizeof(char*)?n_arg:sizeof(_s_arg)/sizeof(char*)-1];
      }

      // Return a string that defines the calling function + the user-defined function scope.
      CImg<charT> s_calling_function() const {
        CImg<charT> res;
        const unsigned int
          l1 = calling_function?(unsigned int)std::strlen(calling_function):0U,
          l2 = user_macro?(unsigned int)std::strlen(user_macro):0U;
        if (l2) {
          res.assign(l1 + l2 + 48);
          cimg_snprintf(res,res._width,"%s(): When substituting function '%s()'",calling_function,user_macro);
        } else {
          res.assign(l1 + l2 + 4);
          cimg_snprintf(res,res._width,"%s()",calling_function);
        }
        return res;
      }

      // Return type of a memory slot as a string.
      CImg<charT> s_type(const unsigned int arg) const {
        CImg<charT> res;
        if (is_vector(arg)) { // Vector
          CImg<charT>::string("vectorXXXXXXXXXXXXXXXX").move_to(res);
          cimg_snprintf(res._data + 6,res._width - 6,"%u",size(arg));
        } else if (is_const_scalar(arg)) CImg<charT>::string("const scalar").move_to(res); // Const scalar
        else CImg<charT>::string("scalar").move_to(res); // Scalar
        return res;
      }

      // Return reference state of a memory slot as a string.
      CImg<charT> s_ref(const unsigned int *const p_ref) const {
        CImg<charT> res;
        if (!p_ref || !*p_ref) return res.assign(1,1,1,1,0);
        res.assign(32);
        switch (p_ref[0]) {
        case 1 : // Reference to vector value as a scalar
          cimg_snprintf(res,res._width,", ref: ([%u])[%u]",
                        p_ref[1],p_ref[2]);
          break;
        case 2 : // Reference to image value as a scalar (offset)
          if (p_ref[1]==~0U)
            cimg_snprintf(res,res._width,", ref: %c[%u]",
                          p_ref[2]?'j':'i',p_ref[3]);
          else
            cimg_snprintf(res,res._width,", ref: %c[#%u,%u]",
                          p_ref[2]?'j':'i',p_ref[1],p_ref[3]);
          break;
        case 3 : // Reference to image value as a scalar (coordinates)
          if (p_ref[1]==~0U)
            cimg_snprintf(res,res._width,", ref: %c(%u,%u,%u,%u)",
                          p_ref[2]?'j':'i',p_ref[3],p_ref[4],p_ref[5],p_ref[6]);
          else
            cimg_snprintf(res,res._width,", ref: %c(#%u,%u,%u,%u,%u)",
                          p_ref[2]?'j':'i',p_ref[1],p_ref[3],p_ref[4],p_ref[5],p_ref[6]);
          break;
        case 4 : // Reference to image value as a vector (offset)
          if (p_ref[1]==~0U)
            cimg_snprintf(res,res._width,", ref: %c[%u]",
                          p_ref[2]?'J':'I',p_ref[3]);
          else
            cimg_snprintf(res,res._width,", ref: %c[#%u,%u]",
                          p_ref[2]?'J':'I',p_ref[1],p_ref[3]);
          break;
        case 5 : // Reference to image value as a vector (coordinates)
          if (p_ref[1]==~0U)
            cimg_snprintf(res,res._width,", ref: %c(%u,%u,%u)",
                          p_ref[2]?'J':'I',p_ref[3],p_ref[4],p_ref[5]);
          else
            cimg_snprintf(res,res._width,", ref: %c(#%u,%u,%u,%u)",
                          p_ref[2]?'J':'I',p_ref[1],p_ref[3],p_ref[4],p_ref[5]);
          break;
        }
        return res;
      }

      // Count parentheses/brackets level of each character of the expression.
      CImg<uintT> get_level(CImg<charT>& _expr) const {
        bool is_escaped = false, next_is_escaped = false;
        unsigned int mode = 0, next_mode = 0; // { 0=normal | 1=char-string | 2=vector-string
        CImg<uintT> res(_expr._width - 1);
        unsigned int *pd = res._data;
        int _level = 0;
        for (const char *ps = _expr._data; *ps && _level>=0; ++ps) {
          if (!is_escaped && !next_is_escaped && *ps=='\\') next_is_escaped = true;
          if (!is_escaped && *ps=='\'') { // Non-escaped character
            if (!mode && ps>_expr._data && *(ps - 1)=='[') next_mode = mode = 2; // Start vector-string
            else if (mode==2 && *(ps + 1)==']') next_mode = !mode; // End vector-string
            else if (mode<2) next_mode = mode?(mode = 0):1; // Start/end char-string
          }
          *(pd++) = (unsigned int)(mode>=1 || is_escaped?_level + (mode==1):
                                   *ps=='(' || *ps=='['?_level++:
                                   *ps==')' || *ps==']'?--_level:
                                   _level);
          mode = next_mode;
          is_escaped = next_is_escaped;
          next_is_escaped = false;
        }
        if (mode) {
          cimg::strellipsize(_expr,64);
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: Unterminated string literal, in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,
                                      _expr._data);
        }
        if (_level) {
          cimg::strellipsize(_expr,64);
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: Unbalanced parentheses/brackets, in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,
                                      _expr._data);
        }
        return res;
      }

      // Find and return index of current image 'imgin' within image list 'imglist'.
      unsigned int get_mem_img_index() {
        if (mem_img_index==~0U) {
          if (&imgout>=imglist.data() && &imgout<imglist.end())
            mem_img_index = const_scalar((double)(&imgout - imglist.data()));
          else {
            unsigned int pos = ~0U;
            cimglist_for(imglist,l)
              if (imgout._data==imglist[l]._data && imgout.is_sameXYZC(imglist[l])) { pos = l; break; }
            if (pos!=~0U) mem_img_index = const_scalar((double)pos);
          }
        }
        return mem_img_index;
      }

      // Return indices for accessing math parser variables.
      void get_variable_pos(const char *variable_name, unsigned int &pos, unsigned int &rpos) {
        char c1, c2, c3, c4;
        pos = rpos = ~0U;
        if (!variable_name || !*variable_name) return;

        unsigned int rp = variable_name[1]?~0U:*variable_name; // One-char variable
        if (variable_name[1] && !variable_name[2]) { // Two-chars variable
          c1 = variable_name[0];
          c2 = variable_name[1];
          if (c1=='w' && c2=='h') rp = 0; // wh
          else if (c1=='p' && c2=='i') rp = 3; // pi
          else if (c1=='_' && c2=='0') rp = 34; // _0
          else if (c1=='_' && c2=='1') rp = 35; // _1
          else if (c1=='i') {
            if (c2>='0' && c2<='9') rp = 21 + c2 - '0'; // i0...i9
            else if (c2=='m') rp = 4; // im
            else if (c2=='M') rp = 5; // iM
            else if (c2=='a') rp = 6; // ia
            else if (c2=='v') rp = 7; // iv
            else if (c2=='d') rp = 8; // id
            else if (c2=='s') rp = 9; // is
            else if (c2=='p') rp = 10; // ip
            else if (c2=='c') rp = 11; // ic
            else if (c2=='n') rp = 12; // in
          } else if (c2=='m') {
            if (c1=='x') rp = 13; // xm
            else if (c1=='y') rp = 14; // ym
            else if (c1=='z') rp = 15; // zm
            else if (c1=='c') rp = 16; // cm
          } else if (c2=='M') {
            if (c1=='x') rp = 17; // xM
            else if (c1=='y') rp = 18; // yM
            else if (c1=='z') rp = 19; // zM
            else if (c1=='c') rp = 20; // cM
          }
        } else if (variable_name[1] && variable_name[2] && !variable_name[3]) { // Three-chars variable
          c1 = variable_name[0];
          c2 = variable_name[1];
          c3 = variable_name[2];
          if (c1=='w' && c2=='h' && c3=='d') rp = 1; // whd
          else if (c1=='e' && c2=='p' && c3=='s') rp = 33; // eps
        } else if (variable_name[1] && variable_name[2] && variable_name[3] &&
                   !variable_name[4]) { // Four-chars variable
          c1 = variable_name[0];
          c2 = variable_name[1];
          c3 = variable_name[2];
          c4 = variable_name[3];
          if (c1=='w' && c2=='h' && c3=='d' && c4=='s') rp = 2; // whds
        } else if (!std::strcmp(variable_name,"interpolation")) rp = 31; // interpolation
        else if (!std::strcmp(variable_name,"boundary")) rp = 32; // boundary

        if (rp!=~0U) { rpos = rp; return; } // One of the reserved labels

        // Multi-char variable name : check for existing variable with same name.
        cimglist_for(variable_def,i)
          if (!std::strcmp(variable_name,variable_def[i])) { pos = i; break; }
      }

      // Return true if all values of a vector are (temporary) computational values.
      bool is_comp_vector(const unsigned int arg) const {
        unsigned int siz = size(arg);
        if (!siz || siz>128) return false;
        const int *ptr = memtype.data(arg + 1);
        bool is_tmp = true;
        while (siz-->0) if (*(ptr++)) { is_tmp = false; break; }
        return is_tmp;
      }

      // Return true if specified scalar value is a (temporary) computational value.
      bool is_comp_scalar(const unsigned int arg) const {
        return !memtype[arg];
      }

      // Return true if specified value is a constant scalar.
      bool is_const_scalar(const unsigned int arg) const {
        return memtype[arg]==1;
      }

      bool is_const_integer(const unsigned int arg) const {
        return memtype[arg]==1 && (double)(int)mem[arg]==mem[arg];
      }

      // Return true if specified value is a scalar reserved value (e.g. variable).
      bool is_reserved(const unsigned int arg) const {
        return memtype[arg]==-1;
      }

      // Return true if specified value is a scalar.
      bool is_scalar(const unsigned int arg) const {
        return memtype[arg]<2;
      }

      // Return true if specified value is a vector.
      bool is_vector(const unsigned int arg) const {
        return memtype[arg]>1;
      }

      // Return size of specified value (0: scalar, N>0: vectorN).
      unsigned int size(const unsigned int arg) const {
        return is_scalar(arg)?0U:memtype[arg] - 1U;
      }

      // Check if a memory slot is a positive integer constant scalar value.
      // 'mode' can be:
      // { 0=constant | 1=integer constant | 2=positive integer constant | 3=strictly-positive integer constant }.
      void check_const_scalar(const unsigned int arg, const unsigned int n_arg,
                              const unsigned int mode,
                              char *const ss, char *const se, const char saved_char) {
        _cimg_mp_check_type(arg,n_arg,1,0);
        if (!is_const_scalar(arg)) {
          const char *const s_arg = s_argth(n_arg);
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s %s%s (of type '%s') is not a constant, "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",
                                      s_arg,*s_arg?" argument":" Argument",s_type(arg)._data,s0);
        }
        const double val = mem[arg];

        if (!((!mode || (double)(int)mem[arg]==mem[arg]) &&
              (mode<2 || mem[arg]>=(mode==3)))) {
          const char *const s_arg = s_argth(n_arg);
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s %s%s (of type '%s' and value %g) is not a%s constant, "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",
                                      s_arg,*s_arg?" argument":" Argument",s_type(arg)._data,val,
                                      !mode?"":mode==1?"n integer":
                                      mode==2?" positive integer":" strictly positive integer",s0);
        }
      }

      // Check if an image index is a constant value.
      void check_const_index(const unsigned int arg,
                             char *const ss, char *const se, const char saved_char) {
        if (arg!=~0U && !is_const_scalar(arg)) {
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s Specified image index is not a constant, "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",s0);
        }
      }

      // Check that specified constant is not nan.
      void check_notnan_index(const unsigned int arg, const char *const s_arg,
                              char *const ss, char *const se, const char saved_char) {
        if (arg!=~0U &&
            (arg==_cimg_mp_slot_nan || (is_const_scalar(arg) && cimg::type<double>::is_nan(mem[arg])))) {
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s Specified index '%s' is NaN.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",s_arg);
        }
      }

      // Check a matrix is square.
      void check_matrix_square(const unsigned int arg, const unsigned int n_arg,
                               char *const ss, char *const se, const char saved_char) {
        _cimg_mp_check_type(arg,n_arg,2,0);
        const unsigned int
          siz = size(arg),
          n = (unsigned int)cimg::round(std::sqrt((float)siz));
        if (n*n!=siz) {
          const char *s_arg;
          if (*s_op!='F') s_arg = !n_arg?"":n_arg==1?"Left-hand":"Right-hand";
          else s_arg = !n_arg?"":n_arg==1?"First":n_arg==2?"Second":n_arg==3?"Third":"One";
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s %s%s (of type '%s') "
                                      "cannot be considered as a square matrix, in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",
                                      s_arg,*s_op=='F'?(*s_arg?" argument":" Argument"):(*s_arg?" operand":" Operand"),
                                      s_type(arg)._data,s0);
        }
      }

      // Check type compatibility for one argument.
      // Bits of 'mode' indicates what types are allowed:
      // { 1 = scalar | 2 = vectorN }.
      // If 'N' is not zero, it also restricts the vectors to be of size N only.
      void check_type(const unsigned int arg, const unsigned int n_arg,
                      const unsigned int mode, const unsigned int N,
                      char *const ss, char *const se, const char saved_char) {
        const bool
          _is_scalar = is_scalar(arg),
          _is_vector = is_vector(arg) && (!N || size(arg)==N);
        bool cond = false;
        if (mode&1) cond|=_is_scalar;
        if (mode&2) cond|=_is_vector;
        if (!cond) {
          const char *s_arg;
          if (*s_op!='F') s_arg = !n_arg?"":n_arg==1?"Left-hand":"Right-hand";
          else s_arg = s_argth(n_arg);
          CImg<charT> sb_type(32);
          if (mode==1) cimg_snprintf(sb_type,sb_type._width,"'scalar'");
          else if (mode==2) {
            if (N) cimg_snprintf(sb_type,sb_type._width,"'vector%u'",N);
            else cimg_snprintf(sb_type,sb_type._width,"'vector'");
          } else {
            if (N) cimg_snprintf(sb_type,sb_type._width,"'scalar' or 'vector%u'",N);
            else cimg_snprintf(sb_type,sb_type._width,"'scalar' or 'vector'");
          }
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s %s%s has invalid type '%s' (should be %s), "
                                      "in expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",
                                      s_arg,*s_op=='F'?(*s_arg?" argument":" Argument"):(*s_arg?" operand":" Operand"),
                                      s_type(arg)._data,sb_type._data,s0);
        }
      }

      // Check that the image list is not empty.
      void check_list(char *const ss, char *const se, const char saved_char) {
        if (!imglist) {
          char *s0;
          _cimg_mp_strerr;
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>::%s: %s%s The image list cannot be empty, for expression '%s'.",
                                      pixel_type(),_cimg_mp_calling_function,s_op,*s_op?":":"",s0);
        }
      }

      static void mp_check_list(_cimg_math_parser& mp, const char *const funcname) {
        if (!mp.imglist)
          throw CImgArgumentException("[" cimg_appname "_math_parser] "
                                      "CImg<%s>: Function '%s()': Images list cannot be empty.",
                                      pixel_type(),funcname);
      }

      // Insert constant value in memory.
      unsigned int const_scalar(const double val) {

        // Search for built-in constant.
        if (cimg::type<double>::is_nan(val)) return _cimg_mp_slot_nan;
        if (val==(double)(int)val) {
          if (val>=0 && val<=10) return (unsigned int)val;
          if (val<0 && val>=-5) return (unsigned int)(10 - val);
        }
        if (val==0.5) return 16;

        // Search for constant already requested before (in const cache).
        unsigned int ind = ~0U;
        if (constcache_size<1024) {
          if (!constcache_size) {
            constcache_vals.assign(16,1,1,1,0);
            constcache_inds.assign(16,1,1,1,0);
            *constcache_vals = val;
            constcache_size = 1;
            ind = 0;
          } else { // Binary search
            const double val_beg = *constcache_vals, val_end = constcache_vals[constcache_size - 1];
            if (val_beg>=val) ind = 0;
            else if (val_end==val) ind = constcache_size - 1;
            else if (val_end<val) ind = constcache_size;
            else {
              unsigned int i0 = 1, i1 = constcache_size - 2;
              while (i0<=i1) {
                const unsigned int mid = (i0 + i1)/2;
                if (constcache_vals[mid]==val) { i0 = mid; break; }
                else if (constcache_vals[mid]<val) i0 = mid + 1;
                else i1 = mid - 1;
              }
              ind = i0;
            }

            if (ind>=constcache_size || constcache_vals[ind]!=val) {
              ++constcache_size;
              if (constcache_size>constcache_vals._width) {
                constcache_vals.resize(-200,1,1,1,0);
                constcache_inds.resize(-200,1,1,1,0);
              }
              const int l = constcache_size - (int)ind - 1;
              if (l>0) {
                std::memmove(&constcache_vals[ind + 1],&constcache_vals[ind],l*sizeof(double));
                std::memmove(&constcache_inds[ind + 1],&constcache_inds[ind],l*sizeof(unsigned int));
              }
              constcache_vals[ind] = val;
              constcache_inds[ind] = 0;
            }
          }
          if (constcache_inds[ind]) return constcache_inds[ind];
        }

        // Insert new constant in memory if necessary.
        if (mempos>=mem._width) { mem.resize(-200,1,1,1,0); memtype.resize(-200,1,1,1,0); }
        const unsigned int pos = mempos++;
        mem[pos] = val;
        memtype[pos] = 1; // Set constant property
        if (ind!=~0U) constcache_inds[ind] = pos;
        return pos;
      }

      // Insert new scalar in memory.
      unsigned int scalar() {
        if (mempos>=mem._width) { mem.resize(-200,1,1,1,0); memtype.resize(mem._width,1,1,1,0); }
        return mempos++;
      }

      // Insert new vector of specified size in memory.
      unsigned int vector(const unsigned int siz) {
        if (!siz) return _cimg_mp_slot_nan;
        if (mempos + siz>=mem._width) {
          mem.resize(2*mem._width + siz,1,1,1,0);
          memtype.resize(mem._width,1,1,1,0);
        }
        const unsigned int pos = mempos++;
        mem[pos] = cimg::type<double>::nan();
        memtype[pos] = siz + 1;
        mempos+=siz;
        return pos;
      }

      // Insert new initialized vector.
      unsigned int vector(const unsigned int siz, const double value) {
        const unsigned int pos = vector(siz);
        double *ptr = &mem[pos] + 1;
        for (unsigned int i = 0; i<siz; ++i) *(ptr++) = value;
        return pos;
      }

      // Return a copy of the specified value.
      // (This forces a copy to be made. Use 'same()' if you only want to return 'arg' without copying).
      unsigned int copy(const unsigned int arg) {
        const unsigned int siz = size(arg);
        return_comp = true;
        if (siz) { // Vector
          const unsigned int pos = vector(siz);
          CImg<ulongT>::vector((ulongT)mp_vector_copy,pos,arg,siz).move_to(code);
          return pos;
        }
        return scalar1(mp_copy,arg); // Scalar
      }

      // Return same value as specified.
      // (This avoids copying when possible. Use 'copy()' to force a copy).
      unsigned int same(const unsigned int arg) {
        if (is_const_scalar(arg)) return arg;
        if (is_comp_scalar(arg)) { return_comp = true; return arg; }
        const unsigned int siz = size(arg);
        if (siz) { // Vector
          if (is_comp_vector(arg)) { return_comp = true; return arg; }
          const unsigned int pos = vector(siz);
          CImg<ulongT>::vector((ulongT)mp_vector_copy,pos,arg,siz).move_to(code);
          return pos;
        }
        return_comp = true;
        return scalar1(mp_copy,arg); // Scalar
      }

      // Set reserved status to all values of a vector.
      void set_reserved_vector(const unsigned int arg) {
        unsigned int siz = size(arg);
        int *ptr = memtype.data(arg + 1);
        while (siz-->0) *(ptr++) = -1;
      }

      unsigned int scalar0(const mp_func op) {
        const unsigned int pos = scalar();
        CImg<ulongT>::vector((ulongT)op,pos).move_to(code);
        return_comp = true;
        return pos;
      }

      unsigned int scalar1(const mp_func op,
                           const unsigned int arg1) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1) && op!=mp_copy?arg1:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1).move_to(code);
        return pos;
      }

      unsigned int scalar2(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2).move_to(code);
        return pos;
      }

      unsigned int scalar3(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          arg3!=~0U && arg3>_cimg_mp_slot_c && is_comp_scalar(arg3)?arg3:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2,arg3).move_to(code);
        return pos;
      }

      unsigned int scalar4(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3,
                           const unsigned int arg4) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          arg3!=~0U && arg3>_cimg_mp_slot_c && is_comp_scalar(arg3)?arg3:
          arg4!=~0U && arg4>_cimg_mp_slot_c && is_comp_scalar(arg4)?arg4:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2,arg3,arg4).move_to(code);
        return pos;
      }

      unsigned int scalar5(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3,
                           const unsigned int arg4, const unsigned int arg5) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          arg3!=~0U && arg3>_cimg_mp_slot_c && is_comp_scalar(arg3)?arg3:
          arg4!=~0U && arg4>_cimg_mp_slot_c && is_comp_scalar(arg4)?arg4:
          arg5!=~0U && arg5>_cimg_mp_slot_c && is_comp_scalar(arg5)?arg5:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2,arg3,arg4,arg5).move_to(code);
        return pos;
      }

      unsigned int scalar6(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3,
                           const unsigned int arg4, const unsigned int arg5, const unsigned int arg6) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          arg3!=~0U && arg3>_cimg_mp_slot_c && is_comp_scalar(arg3)?arg3:
          arg4!=~0U && arg4>_cimg_mp_slot_c && is_comp_scalar(arg4)?arg4:
          arg5!=~0U && arg5>_cimg_mp_slot_c && is_comp_scalar(arg5)?arg5:
          arg6!=~0U && arg6>_cimg_mp_slot_c && is_comp_scalar(arg6)?arg6:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2,arg3,arg4,arg5,arg6).move_to(code);
        return pos;
      }

      unsigned int scalar8(const mp_func op,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3,
                           const unsigned int arg4, const unsigned int arg5, const unsigned int arg6,
                           const unsigned int arg7, const unsigned int arg8) {
        const unsigned int pos =
          arg1!=~0U && arg1>_cimg_mp_slot_c && is_comp_scalar(arg1)?arg1:
          arg2!=~0U && arg2>_cimg_mp_slot_c && is_comp_scalar(arg2)?arg2:
          arg3!=~0U && arg3>_cimg_mp_slot_c && is_comp_scalar(arg3)?arg3:
          arg4!=~0U && arg4>_cimg_mp_slot_c && is_comp_scalar(arg4)?arg4:
          arg5!=~0U && arg5>_cimg_mp_slot_c && is_comp_scalar(arg5)?arg5:
          arg6!=~0U && arg6>_cimg_mp_slot_c && is_comp_scalar(arg6)?arg6:
          arg7!=~0U && arg7>_cimg_mp_slot_c && is_comp_scalar(arg7)?arg7:
          arg8!=~0U && arg8>_cimg_mp_slot_c && is_comp_scalar(arg8)?arg8:
          ((return_comp = true), scalar());
        CImg<ulongT>::vector((ulongT)op,pos,arg1,arg2,arg3,arg4,arg5,arg6,arg7,arg8).move_to(code);
        return pos;
      }

      unsigned int vector1(const mp_func op, const unsigned int siz,
                           const unsigned int arg1) {
        const unsigned int pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(siz));
        CImg<ulongT>::vector((ulongT)op,pos,siz,arg1).move_to(code);
        return pos;
      }

      unsigned int vector2(const mp_func op, const unsigned int siz,
                           const unsigned int arg1, const unsigned int arg2) {
        const unsigned int pos = is_comp_vector(arg1)?arg1:
          is_comp_vector(arg2)?arg2:((return_comp = true), vector(siz));
        CImg<ulongT>::vector((ulongT)op,pos,siz,arg1,arg2).move_to(code);
        return pos;
      }

      unsigned int vector3(const mp_func op, const unsigned int siz,
                           const unsigned int arg1, const unsigned int arg2, const unsigned int arg3) {
        const unsigned int pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(siz));
        CImg<ulongT>::vector((ulongT)op,pos,siz,arg1,arg2,arg3).move_to(code);
        return pos;
      }

      // Evaluation mathematical operators and functions, known by the parser.
      // Defining these functions 'static' ensures that sizeof(mp_func)==sizeof(ulongT),
      // so we can store pointers to them directly in the opcode vectors.
#ifdef _mp_arg
#undef _mp_arg
#endif
#define _mp_arg(x) mp.mem[mp.opcode[x]]

#define _cimg_mp_func1(nm,fn) \
      static double mp_##nm(_cimg_math_parser& mp) { \
        const double arg0 = _mp_arg(2); \
        return (double)(fn); \
      } \
      static double mp_vector_##nm(_cimg_math_parser& mp) { \
        double *ptrd = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        const double *ptr0 = &_mp_arg(3) + 1; \
        for (unsigned int k = 0; k<siz; ++k) { const double arg0 = ptr0[k]; ptrd[k] = (double)(fn); } \
        return cimg::type<double>::nan(); \
      }

      _cimg_mp_func1(abs,cimg::abs(arg0));
      _cimg_mp_func1(acos,std::acos(arg0));
      _cimg_mp_func1(acosh,std::acosh(arg0));
      _cimg_mp_func1(asin,std::asin(arg0));
      _cimg_mp_func1(asinh,std::asinh(arg0));
      _cimg_mp_func1(atan,std::atan(arg0));
      _cimg_mp_func1(atanh,std::atanh(arg0));
      _cimg_mp_func1(bitwise_not,~(unsigned int)(int64T)arg0);
      _cimg_mp_func1(bool,(bool)arg0);
      _cimg_mp_func1(cbrt,cimg::cbrt(arg0));
      _cimg_mp_func1(ceil,std::ceil(arg0));
      _cimg_mp_func1(cos,std::cos(arg0));
      _cimg_mp_func1(cosh,std::cosh(arg0));
      _cimg_mp_func1(deg2rad,cimg::deg2rad(arg0));
#if cimg_use_cpp11==1
      _cimg_mp_func1(erf,std::erf(arg0));
#else
      _cimg_mp_func1(erf,(arg0,cimg::type<double>::nan()));
#endif
      _cimg_mp_func1(erfinv,cimg::erfinv(arg0));
      _cimg_mp_func1(exp,std::exp(arg0));
      _cimg_mp_func1(f2ui,cimg::float2uint(arg0));
      _cimg_mp_func1(factorial,cimg::factorial(arg0));
      _cimg_mp_func1(fibonacci,cimg::fibonacci(arg0));
      _cimg_mp_func1(floor,std::floor(arg0));
      _cimg_mp_func1(frac,cimg::frac(arg0));
#if cimg_use_cpp11==1
      _cimg_mp_func1(gamma,std::tgamma(arg0));
#else
      _cimg_mp_func1(gamma,((double)arg0,cimg::type<double>::nan()));
#endif
      _cimg_mp_func1(int,(longT)arg0);
      _cimg_mp_func1(isbool,arg0==0. || arg0==1.);
      _cimg_mp_func1(isfinite,cimg::type<double>::is_finite(arg0));
      _cimg_mp_func1(isinf,cimg::type<double>::is_inf(arg0));
      _cimg_mp_func1(isnan,cimg::type<double>::is_nan(arg0));
      _cimg_mp_func1(log,std::log(arg0));
      _cimg_mp_func1(log10,std::log10(arg0));
      _cimg_mp_func1(log2,cimg::log2(arg0));
      _cimg_mp_func1(logical_not,!arg0);
      _cimg_mp_func1(logit,cimg::logit(arg0));
      _cimg_mp_func1(lowercase,cimg::lowercase(arg0));
      _cimg_mp_func1(minus,-arg0);
      _cimg_mp_func1(rad2deg,cimg::rad2deg(arg0));
      _cimg_mp_func1(sigmoid,cimg::sigmoid(arg0));
      _cimg_mp_func1(sign,cimg::sign(arg0));
      _cimg_mp_func1(sin,std::sin(arg0));
      _cimg_mp_func1(sinc,cimg::sinc(arg0));
      _cimg_mp_func1(sinh,std::sinh(arg0));
      _cimg_mp_func1(sqr,cimg::sqr(arg0));
      _cimg_mp_func1(sqrt,std::sqrt(arg0));
      _cimg_mp_func1(tan,std::tan(arg0));
      _cimg_mp_func1(tanh,std::tanh(arg0));
      _cimg_mp_func1(ui2f,cimg::uint2float(arg0,(T)0));
      _cimg_mp_func1(uppercase,cimg::uppercase(arg0));

#define _cimg_mp_func2(nm,fn) \
      static double mp_##nm(_cimg_math_parser& mp) { \
        const double arg0 = _mp_arg(2), arg1 = _mp_arg(3); \
        return (double)(fn); \
      } \
      static double mp_vector_##nm##_sv(_cimg_math_parser& mp) { \
        double *const ptrd = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        const double arg0 = _mp_arg(3), *const ptr1 = &_mp_arg(4) + 1; \
        for (unsigned int k = 0; k<siz; ++k) { const double arg1 = ptr1[k]; ptrd[k] = (double)(fn); } \
        return cimg::type<double>::nan(); \
      } \
      static double mp_vector_##nm##_vs(_cimg_math_parser& mp) { \
        double *const ptrd = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        const double *const ptr0 = &_mp_arg(3) + 1, arg1 = _mp_arg(4); \
        for (unsigned int k = 0; k<siz; ++k) { const double arg0 = ptr0[k]; ptrd[k] = (double)(fn); } \
        return cimg::type<double>::nan(); \
      } \
      static double mp_vector_##nm##_vv(_cimg_math_parser& mp) { \
        double *const ptrd = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        const double *const ptr0 = &_mp_arg(3) + 1, *const ptr1 = &_mp_arg(4) + 1; \
        for (unsigned int k = 0; k<siz; ++k) { const double arg0 = ptr0[k], arg1 = ptr1[k]; ptrd[k] = (double)(fn); } \
        return cimg::type<double>::nan(); \
      }

      _cimg_mp_func2(add,arg0 + arg1);
      _cimg_mp_func2(atan2,std::atan2(arg0,arg1));
      _cimg_mp_func2(bitwise_and,(longT)arg0 & (longT)arg1);
      _cimg_mp_func2(bitwise_left_shift,cimg::bsl(arg0,(int)arg1));
      _cimg_mp_func2(bitwise_or,(longT)arg0 | (longT)arg1);
      _cimg_mp_func2(bitwise_right_shift,cimg::bsr(arg0,(int)arg1));
      _cimg_mp_func2(bitwise_xor,(longT)arg0 ^ (longT)arg1);
      _cimg_mp_func2(div,arg0/arg1);
      _cimg_mp_func2(gt,arg0>arg1);
      _cimg_mp_func2(gte,arg0>=arg1);
      _cimg_mp_func2(lt,arg0<arg1);
      _cimg_mp_func2(lte,arg0<=arg1);
      _cimg_mp_func2(modulo,cimg::mod(arg0,arg1));
      _cimg_mp_func2(mul,arg0*arg1);
      _cimg_mp_func2(pow,std::pow(arg0,arg1));
      _cimg_mp_func2(rol,cimg::rol(arg0,(unsigned int)arg1));
      _cimg_mp_func2(ror,cimg::ror(arg0,(unsigned int)arg1));
      _cimg_mp_func2(sub,arg0 - arg1);
      _cimg_mp_func2(rand_double,arg0 + (arg1 - arg0)*(double)cimg::_rand(&mp.rng)/~0U);
      _cimg_mp_func2(rand_int,mp._rand_int_m_M(arg0,arg1));
      _cimg_mp_func2(wave,cimg::wave(arg0,(unsigned int)arg1));

#define _cimg_mp_self_func0(nm,fn) \
      static double mp_self_##nm(_cimg_math_parser& mp) { \
        double &arg0 = _mp_arg(1); \
        return (double)(fn); \
      } \
      static double mp_self_vector_##nm(_cimg_math_parser& mp) { \
        double *const ptr0 = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        for (unsigned int k = 0; k<siz; ++k) { double &arg0 = ptr0[k]; fn; } \
        return cimg::type<double>::nan(); \
      }

      _cimg_mp_self_func0(decrement,--arg0);
      _cimg_mp_self_func0(increment,++arg0);

#define _cimg_mp_self_func1(nm,fn) \
      static double mp_self_##nm(_cimg_math_parser& mp) { \
        double &arg0 = _mp_arg(1); const double arg1 = _mp_arg(2); \
        return arg0 = (double)(fn); \
      } \
      static double mp_self_vector_##nm##_s(_cimg_math_parser& mp) { \
        double *const ptr0 = &_mp_arg(1) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        const double arg1 = _mp_arg(3); \
        for (unsigned int k = 0; k<siz; ++k) { double &arg0 = ptr0[k]; arg0 = (double)(fn); } \
        return cimg::type<double>::nan(); \
      } \
      static double mp_self_vector_##nm##_v(_cimg_math_parser& mp) { \
        double *const ptr0 = &_mp_arg(1) + 1, *const ptr1 = &_mp_arg(3) + 1; \
        const unsigned int siz = (unsigned int)mp.opcode[2]; \
        for (unsigned int k = 0; k<siz; ++k) { \
          double &arg0 = ptr0[k]; const double arg1 = ptr1[k]; arg0 = (double)(fn); \
        } \
        return cimg::type<double>::nan(); \
      }

      _cimg_mp_self_func1(add,arg0 + arg1);
      _cimg_mp_self_func1(bitwise_and,(longT)arg0 & (longT)arg1);
      _cimg_mp_self_func1(bitwise_left_shift,cimg::bsl(arg0,(int)arg1));
      _cimg_mp_self_func1(bitwise_or,(longT)arg0 | (longT)arg1);
      _cimg_mp_self_func1(bitwise_right_shift,cimg::bsr(arg0,(int)arg1));
      _cimg_mp_self_func1(div,arg0/arg1);
      _cimg_mp_self_func1(modulo,cimg::mod(arg0,arg1));
      _cimg_mp_self_func1(mul,arg0*arg1);
      _cimg_mp_self_func1(pow,std::pow(arg0,arg1));
      _cimg_mp_self_func1(sub,arg0 - arg1);

#ifdef cimg_mp_func_abort
      static double mp_abort(_cimg_math_parser& mp) {
        cimg::unused(mp);
        cimg_mp_func_abort();
        return cimg::type<double>::nan();
      }
#else
      static double mp_abort(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_abscut(_cimg_math_parser& mp) {
        return cimg::abscut(_mp_arg(2),_mp_arg(3),_mp_arg(4),_mp_arg(5));
      }

      static double mp_vector_abscut(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const double *const ptrs = &_mp_arg(3) + 1, m = _mp_arg(4), M = _mp_arg(5), off = _mp_arg(6);
        for (unsigned int k = 0; k<siz; ++k) ptrd[k] = cimg::abscut(ptrs[k],m,M,off);
        return cimg::type<double>::nan();
      }

      static double mp_absmaxabs(_cimg_math_parser& mp) {
        return _mp_maxabs(mp,true);
      }

      static double mp_absminabs(_cimg_math_parser& mp) {
        return _mp_minabs(mp,true);
      }

      static double mp_add_add(_cimg_math_parser& mp) {
        return _mp_arg(2) + _mp_arg(3) + _mp_arg(4);
      }

      static double mp_add_mul(_cimg_math_parser& mp) {
        return _mp_arg(2) + _mp_arg(3)*_mp_arg(4);
      }

      static double mp_add_sub(_cimg_math_parser& mp) {
        return _mp_arg(2) + _mp_arg(3) - _mp_arg(4);
      }

      static double mp_arg0(_cimg_math_parser& mp) {
        const int _ind = (int)_mp_arg(4);
        const unsigned int
          nb_args = (unsigned int)mp.opcode[2],
          ind = _ind<0?_ind + nb_args:_ind + 1U,
          siz = (unsigned int)mp.opcode[3];
        if (siz>0) {
          if (ind>=nb_args) std::memset(&_mp_arg(1) + 1,0,siz*sizeof(double));
          else std::memcpy(&_mp_arg(1) + 1,&_mp_arg(ind + 4) + 1,siz*sizeof(double));
          return cimg::type<double>::nan();
        }
        if (ind>=nb_args) return 0;
        return _mp_arg(ind + 4);
      }

      static double mp_arg1(_cimg_math_parser& mp) {
        const int _ind = (int)_mp_arg(4);
        const unsigned int
          nb_args = (unsigned int)mp.opcode[2],
          ind = _ind<0?_ind + nb_args:(unsigned int)_ind,
          siz = (unsigned int)mp.opcode[3];
        if (siz>0) {
          if (ind>=nb_args) std::memset(&_mp_arg(1) + 1,0,siz*sizeof(double));
          else std::memcpy(&_mp_arg(1) + 1,&_mp_arg(ind + 4) + 1,siz*sizeof(double));
          return cimg::type<double>::nan();
        }
        if (ind>=nb_args) return 0;
        return _mp_arg(ind + 4);
      }

      static double mp_argkth(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        CImg<doubleT> values;
        if (i_end==5) values.assign(&_mp_arg(3),(unsigned int)mp.opcode[4],1,1,1,true); // Only a single argument
        else {
          unsigned int siz = 0;
          for (unsigned int i = 4; i<i_end; i+=2) siz+=(unsigned int)mp.opcode[i];
          values.assign(siz);
          double *ptr = values;
          for (unsigned int i = 3; i<i_end; i+=2) {
            const unsigned int len = (unsigned int)mp.opcode[i + 1];
            if (len>1) std::memcpy(ptr,&_mp_arg(i),len*sizeof(double));
            else *ptr = _mp_arg(i);
            ptr+=len;
          }
        }
        longT ind = (longT)cimg::round(_mp_arg(3));
        ++values._data; --values._width; // Skip first value
        if (ind<0) ind+=values.width() + 1;
        ind = cimg::cut(ind,(longT)1,(longT)values.width());
        const double kth = values.kth_smallest((ulongT)(ind - 1));
        --values._data; ++values._width;
        for (unsigned int argkth = 1; argkth<values._width; ++argkth)
          if (values[argkth]==kth) return argkth;
        return cimg::type<double>::nan();
      }

      static double mp_argmax(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, valmax = -cimg::type<double>::inf();
        unsigned int siz = 0, argmax = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) { val = *(ptr++); if (val>valmax) { valmax = val; argmax = siz + k; } }
          } else { val = _mp_arg(i); if (val>valmax) { valmax = val; argmax = siz; } }
          siz+=len;
        }
        return (double)argmax;
      }

      static double mp_argmax2(_cimg_math_parser& mp) {
        return _mp_arg(2)>=_mp_arg(3)?0:1;
      }

      static double mp_argmaxabs(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, abs_val, abs_valmaxabs = 0;
        unsigned int siz = 0, argmaxabs = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) {
              val = *(ptr++);
              abs_val = cimg::abs(val);
              if (abs_val>abs_valmaxabs) { abs_valmaxabs = abs_val; argmaxabs = siz + k; }
            }
          } else {
            val = _mp_arg(i);
            abs_val = cimg::abs(val);
            if (abs_val>abs_valmaxabs) { abs_valmaxabs = abs_val; argmaxabs = siz; }
          }
          siz+=len;
        }
        return (double)argmaxabs;
      }

      static double mp_argmaxabs2(_cimg_math_parser& mp) {
        return cimg::abs(_mp_arg(2))>=cimg::abs(_mp_arg(3))?0:1;
      }

      static double mp_argmin(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, valmin = cimg::type<double>::inf();
        unsigned int siz = 0, argmin = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) { val = *(ptr++); if (val<valmin) { valmin = val; argmin = siz + k; } }
          } else { val = _mp_arg(i); if (val<valmin) { valmin = val; argmin = siz; } }
          siz+=len;
        }
        return (double)argmin;
      }

      static double mp_argmin2(_cimg_math_parser& mp) {
        return _mp_arg(2)<=_mp_arg(3)?0:1;
      }

      static double mp_argminabs(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, abs_val, abs_valminabs = cimg::type<double>::inf();
        unsigned int siz = 0, argminabs = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) {
              val = *(ptr++);
              abs_val = cimg::abs(val);
              if (abs_val<abs_valminabs) { abs_valminabs = abs_val; argminabs = siz + k; }
            }
          } else {
            val = _mp_arg(i);
            abs_val = cimg::abs(val);
            if (abs_val<abs_valminabs) { abs_valminabs = abs_val; argminabs = siz; }
          }
          siz+=len;
        }
        return (double)argminabs;
      }

      static double mp_argminabs2(_cimg_math_parser& mp) {
        return cimg::abs(_mp_arg(2))<=cimg::abs(_mp_arg(3))?0:1;
      }

      static double mp_avg(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        unsigned int siz = 0;
        double sum = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) sum+=*(ptr++);
          } else sum+=_mp_arg(i);
          siz+=len;
        }
        return sum/siz;
      }

      static double mp_avg2(_cimg_math_parser& mp) {
        return (_mp_arg(2) + _mp_arg(3))/2;
      }

      static double mp_break(_cimg_math_parser& mp) {
        mp.break_type = 1;
        mp.p_code = mp.p_break - 1;
        return cimg::type<double>::nan();
      }

      static double mp_breakpoint(_cimg_math_parser& mp) {
        cimg_abort_init;
        cimg_abort_test;
        cimg::unused(mp);
        return cimg::type<double>::nan();
      }

      static double mp_c2o(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          mp_check_list(mp,"c2o");
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const int x = (int)_mp_arg(3), y = (int)_mp_arg(4), z = (int)_mp_arg(5), c = (int)_mp_arg(6);
        const bool
          boundary_conditions = (bool)_mp_arg(7),
          is_contained = boundary_conditions?img.containsXYZC(x,y,z,c):true;
        return is_contained?img.offset(x,y,z,c):-1;
      }

      static double mp_complex_abs(_cimg_math_parser& mp) {
        return cimg::hypot(_mp_arg(2),_mp_arg(3));
      }

      static double mp_complex_conj(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = real;
        ptrd[1] = -imag;
        return cimg::type<double>::nan();
      }

      static double mp_complex_cos(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = std::cos(real)*std::cosh(imag);
        ptrd[1] = -std::sin(real)*std::sinh(imag);
        return cimg::type<double>::nan();
      }

      static double mp_complex_cosh(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = std::cosh(real)*std::cos(imag);
        ptrd[1] = std::sinh(real)*std::sin(imag);
        return cimg::type<double>::nan();
      }

      static double mp_complex_div_sv(_cimg_math_parser& mp) {
        const double
          *ptr2 = &_mp_arg(3) + 1,
          r1 = _mp_arg(2),
          r2 = *(ptr2++), i2 = *ptr2;
        double *ptrd = &_mp_arg(1) + 1;
        const double denom = r2*r2 + i2*i2;
        *(ptrd++) = r1*r2/denom;
        *ptrd =  -r1*i2/denom;
        return cimg::type<double>::nan();
      }

      static double mp_complex_div_vv(_cimg_math_parser& mp) {
        const double
          *ptr1 = &_mp_arg(2) + 1, *ptr2 = &_mp_arg(3) + 1,
          r1 = *(ptr1++), i1 = *ptr1,
          r2 = *(ptr2++), i2 = *ptr2;
        double *ptrd = &_mp_arg(1) + 1;
        const double denom = r2*r2 + i2*i2;
        *(ptrd++) = (r1*r2 + i1*i2)/denom;
        *ptrd = (r2*i1 - r1*i2)/denom;
        return cimg::type<double>::nan();
      }

      static double mp_complex_exp(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1],
          exp_real = std::exp(real);
        ptrd[0] = exp_real*std::cos(imag);
        ptrd[1] = exp_real*std::sin(imag);
        return cimg::type<double>::nan();
      }

      static double mp_complex_log(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = 0.5*std::log(real*real + imag*imag);
        ptrd[1] = std::atan2(imag,real);
        return cimg::type<double>::nan();
      }

      static double mp_complex_mul(_cimg_math_parser& mp) {
        const double
          *ptr1 = &_mp_arg(2) + 1, *ptr2 = &_mp_arg(3) + 1,
          r1 = *(ptr1++), i1 = *ptr1,
          r2 = *(ptr2++), i2 = *ptr2;
        double *ptrd = &_mp_arg(1) + 1;
        *(ptrd++) = r1*r2 - i1*i2;
        *(ptrd++) = r1*i2 + r2*i1;
        return cimg::type<double>::nan();
      }

      static double mp_complex_one(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        ptrd[0] = 1;
        ptrd[1] = 0;
        return cimg::type<double>::nan();
      }

      static void _mp_complex_pow(const double r1, const double i1,
                                  const double r2, const double i2,
                                  double *ptrd) {
        double ro, io;
        if (cimg::abs(i2)<1e-15) { // Exponent is real
          if (cimg::abs(r1)<1e-15 && cimg::abs(i1)<1e-15) {
            if (cimg::abs(r2)<1e-15) { ro = 1; io = 0; }
            else ro = io = 0;
          } else {
            const double
              mod1_2 = r1*r1 + i1*i1,
              phi1 = std::atan2(i1,r1),
              modo = std::pow(mod1_2,0.5*r2),
              phio = r2*phi1;
            ro = modo*std::cos(phio);
            io = modo*std::sin(phio);
          }
        } else { // Exponent is complex
          if (cimg::abs(r1)<1e-15 && cimg::abs(i1)<1e-15) ro = io = 0;
          const double
            mod1_2 = r1*r1 + i1*i1,
            phi1 = std::atan2(i1,r1),
            modo = std::pow(mod1_2,0.5*r2)*std::exp(-i2*phi1),
            phio = r2*phi1 + 0.5*i2*std::log(mod1_2);
          ro = modo*std::cos(phio);
          io = modo*std::sin(phio);
        }
        *(ptrd++) = ro;
        *ptrd = io;
      }

      static double mp_complex_pow_ss(_cimg_math_parser& mp) {
        const double val1 = _mp_arg(2), val2 = _mp_arg(3);
        double *ptrd = &_mp_arg(1) + 1;
        _mp_complex_pow(val1,0,val2,0,ptrd);
        return cimg::type<double>::nan();
      }

      static double mp_complex_pow_sv(_cimg_math_parser& mp) {
        const double val1 = _mp_arg(2), *ptr2 = &_mp_arg(3) + 1;
        double *ptrd = &_mp_arg(1) + 1;
        _mp_complex_pow(val1,0,ptr2[0],ptr2[1],ptrd);
        return cimg::type<double>::nan();
      }

      static double mp_complex_pow_vs(_cimg_math_parser& mp) {
        const double *ptr1 = &_mp_arg(2) + 1, val2 = _mp_arg(3);
        double *ptrd = &_mp_arg(1) + 1;
        _mp_complex_pow(ptr1[0],ptr1[1],val2,0,ptrd);
        return cimg::type<double>::nan();
      }

      static double mp_complex_pow_vv(_cimg_math_parser& mp) {
        const double *ptr1 = &_mp_arg(2) + 1, *ptr2 = &_mp_arg(3) + 1;
        double *ptrd = &_mp_arg(1) + 1;
        _mp_complex_pow(ptr1[0],ptr1[1],ptr2[0],ptr2[1],ptrd);
        return cimg::type<double>::nan();
      }

      static double mp_complex_sin(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = std::sin(real)*std::cosh(imag);
        ptrd[1] = std::cos(real)*std::sinh(imag);
        return cimg::type<double>::nan();
      }

      static double mp_complex_sinh(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = std::sinh(real)*std::cos(imag);
        ptrd[1] = std::cosh(real)*std::sin(imag);
        return cimg::type<double>::nan();
      }

      static double mp_complex_sqr(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1];
        ptrd[0] = cimg::sqr(real) - cimg::sqr(imag);
        ptrd[1] = 2*real*imag;
        return cimg::type<double>::nan();
      }

      static double mp_complex_sqrt(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1],
          r = std::sqrt(cimg::hypot(real,imag)), theta = std::atan2(imag,real)/2;
        ptrd[0] = r*std::cos(theta);
        ptrd[1] = r*std::sin(theta);
        return cimg::type<double>::nan();
      }

      static double mp_complex_tan(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1],
          denom = std::cos(2*real) + std::cosh(2*imag);
        ptrd[0] = std::sin(2*real)/denom;
        ptrd[1] = std::sinh(2*imag)/denom;
        return cimg::type<double>::nan();
      }

      static double mp_complex_tanh(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(3) + 1, real = ptrs[0], imag = ptrs[1],
          denom = std::cosh(2*real) + std::cos(2*imag);
        ptrd[0] = std::sinh(2*real)/denom;
        ptrd[1] = std::sin(2*imag)/denom;
        return cimg::type<double>::nan();
      }

      static double mp_continue(_cimg_math_parser& mp) {
        mp.break_type = 2;
        mp.p_code = mp.p_break - 1;
        return cimg::type<double>::nan();
      }

      static double mp_convolve(_cimg_math_parser& mp) {
        return _mp_correlate(mp,true);
      }

      static double mp_copy(_cimg_math_parser& mp) {
        return _mp_arg(2);
      }

      static double mp_correlate(_cimg_math_parser& mp) {
        return _mp_correlate(mp,false);
      }

      static double _mp_correlate(_cimg_math_parser& mp, bool is_convolve) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *const ptrI = &_mp_arg(2) + 1, *const ptrK = &_mp_arg(7) + 1;
        const unsigned int
          wI = (unsigned int)mp.opcode[3],
          hI = (unsigned int)mp.opcode[4],
          dI = (unsigned int)mp.opcode[5],
          sI = (unsigned int)mp.opcode[6],
          wK = (unsigned int)mp.opcode[8],
          hK = (unsigned int)mp.opcode[9],
          dK = (unsigned int)mp.opcode[10],
          sK = (unsigned int)mp.opcode[11],
          boundary_conditions = (unsigned int)_mp_arg(12),
          channel_mode = (unsigned int)mp.opcode[14],
          xstride = (unsigned int)mp.opcode[18],
          ystride = (unsigned int)mp.opcode[19],
          zstride = (unsigned int)mp.opcode[20],
          xsize = (unsigned int)mp.opcode[27],
          ysize = (unsigned int)mp.opcode[28],
          zsize = (unsigned int)mp.opcode[29];
        const bool is_normalized = (bool)_mp_arg(13);
        const int
          xcenter = mp.opcode[15]!=~0U?(int)_mp_arg(15):(int)(~0U>>1),
          ycenter = mp.opcode[16]!=~0U?(int)_mp_arg(16):(int)(~0U>>1),
          zcenter = mp.opcode[17]!=~0U?(int)_mp_arg(17):(int)(~0U>>1),
          xdilation = (int)_mp_arg(21),
          ydilation = (int)_mp_arg(22),
          zdilation = (int)_mp_arg(23),
          xoffset = (int)_mp_arg(24),
          yoffset = (int)_mp_arg(25),
          zoffset = (int)_mp_arg(26);
        CImg<doubleT> res;
        if (is_convolve)
          res = CImg<doubleT>(ptrI,wI,hI,dI,sI,true).
            get_convolve(CImg<doubleT>(ptrK,wK,hK,dK,sK,true),
                         boundary_conditions,is_normalized,channel_mode,
                         xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                         xoffset,yoffset,zoffset,xsize,ysize,zsize);
        else
          res = CImg<doubleT>(ptrI,wI,hI,dI,sI,true).
            get_correlate(CImg<doubleT>(ptrK,wK,hK,dK,sK,true),
                          boundary_conditions,is_normalized,channel_mode,
                          xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                          xoffset,yoffset,zoffset,xsize,ysize,zsize);
        CImg<doubleT>(ptrd,res._width,res._height,res._depth,res._spectrum,true) = res;
        return cimg::type<double>::nan();
      }

      static double mp_cov(_cimg_math_parser& mp) {
        const unsigned int
          _siz = (unsigned int)mp.opcode[4],
          siz = std::max(_siz,1U),
          off = _siz?1:0,
          sizm1 = siz>1?siz - 1:1;
        const CImg<doubleT>
          A(&_mp_arg(2) + off,1,siz,1,1,true),
          B(&_mp_arg(3) + off,1,siz,1,1,true);
        const double
          avgA = (unsigned int)mp.opcode[5]==~0U?A.mean():_mp_arg(5),
          avgB = (unsigned int)mp.opcode[6]==~0U?B.mean():_mp_arg(6);
        double res = 0;
        cimg_forY(A,k) res+=(A[k] - avgA)*(B[k] - avgB);
        return res/sizm1;
      }

      static double mp_critical(_cimg_math_parser& mp) {
        const ulongT g_target = mp.opcode[1];
        cimg_pragma_openmp(critical(mp_critical)) {
          const CImg<ulongT> *const p_end = ++mp.p_code + mp.opcode[2];
          mp.eval(mp.p_code,p_end);
        }
        --mp.p_code;
        return mp.mem[g_target];
      }

      static double mp_cross(_cimg_math_parser& mp) {
        CImg<doubleT>
          vout(&_mp_arg(1) + 1,1,3,1,1,true),
          v1(&_mp_arg(2) + 1,1,3,1,1,true),
          v2(&_mp_arg(3) + 1,1,3,1,1,true);
        (vout = v1).cross(v2);
        return cimg::type<double>::nan();
      }

      static double mp_cumulate(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double
          *const ptrs = &_mp_arg(2) + 1,
          *const ptrp = sizp!=~0U?&_mp_arg(7) + 1:0;
        CImg<charT> str;
        if (ptrp) {
          str.assign(std::max(1U,sizp) + 1);
          if (!sizp) str[0] = _mp_arg(7);
          else for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
          str.back() = 0;
        }
        CImg<doubleT>(ptrd,wA,hA,dA,sA,true) = CImg<doubleT>(ptrs,wA,hA,dA,sA,true).
          get_cumulate(str);
        return cimg::type<double>::nan();
      }

      static double mp_cumulate_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double *const ptrp = sizp!=~0U?&_mp_arg(7) + 1:0;
        CImg<charT> str;
        if (ptrp) {
          str.assign(std::max(1U,sizp) + 1);
          if (!sizp) str[0] = _mp_arg(7);
          else for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
          str.back() = 0;
        }
        CImg<doubleT>(ptrs,wA,hA,dA,sA,true).cumulate(str);
        return cimg::type<double>::nan();
      }

      static double mp_cut(_cimg_math_parser& mp) {
        double val = _mp_arg(2), cmin = _mp_arg(3), cmax = _mp_arg(4);
        return cimg::cut(val,cmin,cmax);
      }

      static double mp_vector_cut(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const double *const ptrs = &_mp_arg(3) + 1, cmin = _mp_arg(4), cmax = _mp_arg(5);
        for (unsigned int k = 0; k<siz; ++k) ptrd[k] = (double)cimg::cut(ptrs[k],cmin,cmax);
        return cimg::type<double>::nan();
      }

      static double mp_da_back_or_pop(_cimg_math_parser& mp) {
        const bool is_pop_heap = mp.opcode[4]==2, is_pop = (bool)mp.opcode[4];
        const char *const s_op = is_pop_heap?"da_pop_heap":is_pop?"da_pop":"da_back";
        mp_check_list(mp,s_op);
        const unsigned int
          dim = (unsigned int)mp.opcode[2],
          ind = (unsigned int)cimg::mod((int)_mp_arg(3),mp.imglist.width());
        double *const ptrd = &_mp_arg(1) + (dim>1?1:0);
        CImg<T> &img = mp.imglist[ind];
        int siz = img?(int)cimg::float2uint(img[img._height - 1]):0;
        if (img && (img._width!=1 || img._depth!=1 || siz<0 || siz>img.height() - 1))
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Specified image #%u of size (%d,%d,%d,%d) cannot be used as dynamic array%s.",
                                      mp.imgout.pixel_type(),s_op,ind,
                                      img.width(),img.height(),img.depth(),img.spectrum(),
                                      img._width==1 && img._depth==1?"":" (contains invalid element counter)");
        if (!siz)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Specified dynamic array #%u contains no elements.",
                                      mp.imgout.pixel_type(),s_op,ind);
        const int siz1 = siz - 1;
        if (is_pop_heap) { // Heapify-down
          if (dim==1) cimg::swap(img[0],img[siz1]);
          else {
            T *ptr0 = img.data(), *ptr1 = img.data(0,siz1);
            cimg_forC(img,c) { cimg::swap(*ptr0,*ptr1); ptr0+=img._height; ptr1+=img._height; }
          }
          int index = 0;
          while (true) {
            const int child_left = 2*index + 1, child_right = child_left + 1;
            int smallest = index;
            if (child_left<siz1 && img[child_left]<img[smallest]) smallest = child_left;
            if (child_right<siz1 && img[child_right]<img[smallest]) smallest = child_right;
            if (smallest!=index) {
              if (dim==1) cimg::swap(img[index],img[smallest]);
              else {
                T *ptr0 = img.data(0,index), *ptr1 = img.data(0,smallest);
                cimg_forC(img,c) { cimg::swap(*ptr0,*ptr1); ptr0+=img._height; ptr1+=img._height; }
              }
              index = smallest;
            } else break;
          }
        }

        double ret = cimg::type<double>::nan();
        if (dim==1) ret = img[siz1]; // Scalar element
        else {
          const T *ptrs = img.data(0,siz1);
          cimg_forC(img,c) { ptrd[c] = *ptrs; ptrs+=img._height; } // Vector element
        }
        if (is_pop) { // Remove element from array
          --siz;
          if (img.height()>32 && siz<img.height()/8) // Reduce size of dynamic array
            img.resize(1,std::max(2*siz + 1,32),1,-100,0);
          img[img._height - 1] = cimg::uint2float(siz,(T)0);
        }
        return ret;
      }

      static double mp_da_freeze(_cimg_math_parser& mp) {
        const char *const s_op = "da_freeze";
        mp_check_list(mp,s_op);
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        CImg<T> &img = mp.imglist[ind];
        int siz = img?(int)cimg::float2uint(img[img._height - 1]):0;
        if (img && (img._width!=1 || img._depth!=1 || siz<0 || siz>img.height() - 1))
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Specified image #%u of size (%d,%d,%d,%d) cannot be used as dynamic array%s.",
                                      mp.imgout.pixel_type(),s_op,ind,
                                      img.width(),img.height(),img.depth(),img.spectrum(),
                                      img._width==1 && img._depth==1?"":" (contains invalid element counter)");
        if (siz) img.resize(1,siz,1,-100,0,0); else img.assign();
        return cimg::type<double>::nan();
      }

      static double mp_da_insert_or_push_n(_cimg_math_parser& mp) {
        const unsigned int count = (unsigned int)(mp.opcode[3]==~0U?1:std::max(_mp_arg(3),0.));
        if (!count) return cimg::type<double>::nan();
        const bool
          is_n = mp.opcode[3]!=~0U,
          is_push_heap = mp.opcode[4]==~0U - 1,
          is_push = mp.opcode[4]>=~0U - 1;
        const char *const s_op =
          is_push_heap?(is_n?"da_push_heap_n":"da_push_heap"):
          is_push?(is_n?"da_push_n":"da_push"):
          (is_n?"da_insert_n":"da_insert");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        CImg<T> &img = mp.imglist[ind];
        mp_check_list(mp,s_op);
        const unsigned int
          dim = (unsigned int)(mp.opcode[5]==~0U?img._spectrum:mp.opcode[5]),
          dim1 = std::max(1U,dim),
          nb_elts = (unsigned int)mp.opcode[6],
          nb_elts1 = std::max(1U,nb_elts);
        const int
          siz = img?(int)cimg::float2uint(img[img._height - 1]):0,
          pos0 = is_push?siz:(int)_mp_arg(4),
          pos = pos0<0?pos0 + siz:pos0;

        if (img && dim1!=img._spectrum)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Element to insert has invalid size %u (should be %u).",
                                      mp.imgout.pixel_type(),s_op,dim1,img._spectrum);
        if (img && (img._width!=1 || img._depth!=1 || siz<0 || siz>img.height() - 1))
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Specified image #%u of size (%d,%d,%d,%d) cannot be used as dynamic array%s.",
                                      mp.imgout.pixel_type(),s_op,ind,
                                      img.width(),img.height(),img.depth(),img.spectrum(),
                                      img._width==1 && img._depth==1?"":" (contains invalid element counter)");
        if (pos<0 || pos>siz)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function '%s()': "
                                      "Invalid position %d (not in range -%d...%d).",
                                      mp.imgout.pixel_type(),s_op,pos0,siz,siz);

        if (siz + count*nb_elts1 + 1>=img._height) // Increase size of dynamic array, if necessary
          img.resize(1,2*siz + count*nb_elts1 + 1,1,dim1,0);

        if (pos!=siz) // Move existing data in dynamic array
          cimg_forC(img,c) std::memmove(img.data(0,pos + count*nb_elts1,0,c),img.data(0,pos,0,c),(siz - pos)*sizeof(T));

        if (dim1==1) { // Scalar or vector1() elements
          if (nb_elts) {
            for (unsigned int k = 0; k<nb_elts; ++k) img[pos + k] = (T)_mp_arg(7 + k);
            if (count>1) // Exponentially recopy sequence of scalar elements
              for (unsigned int k = 1; k<count; k<<=1)
                std::memcpy(&img[pos + k*nb_elts],&img[pos],std::min(k,count - k)*nb_elts*sizeof(T));
          } else std::memset(&img[pos],0,count*sizeof(T));
          if (is_push_heap) for (unsigned int k = 0; k<count*nb_elts1; ++k) {
              int index = pos + k;
              while (index>0) { // Heapify-up
                const int index_parent = (index - 1)/2;
                if (img[index]<img[index_parent]) {
                  cimg::swap(img[index],img[index_parent]);
                  index = index_parent; }
                else break;
              }
            }
        } else { // vectorN() elements, with N>1
          if (nb_elts) {
            for (unsigned int k = 0; k<nb_elts; ++k) {
              T *ptrd = img.data(0,pos + k);
              const double *const ptrs = &_mp_arg(7 + k) + 1;
              cimg_forC(img,c) { *ptrd = ptrs[c]; ptrd+=img._height; }
            }
            if (count>1) // Exponentially recopy sequence of vector-valued elements
              cimg_forC(img,c) {
                T *const ptr = img.data(0,0,0,c);
                for (unsigned int k = 1; k<count; k<<=1)
                  std::memcpy(&ptr[pos + k*nb_elts],&ptr[pos],std::min(k,count - k)*nb_elts*sizeof(T));
              }
          } else cimg_forC(img,c) std::memset(img.data(0,pos,0,c),0,count*sizeof(T));
          if (is_push_heap) for (unsigned int k = 0; k<count*nb_elts1; ++k) {
              int index = pos + k;
              while (index>0) { // Heapify-up
                const int index_parent = (index - 1)/2;
                if (img[index]<img[index_parent]) {
                  T *ptr0 = img.data(0,index), *ptr1 = img.data(0,index_parent);
                  cimg_forC(img,c) { cimg::swap(*ptr0,*ptr1); ptr0+=img._height; ptr1+=img._height; }
                  index = index_parent;
                }
                else break;
              }
            }
        }
        img[img._height - 1] = cimg::uint2float(siz + count*nb_elts1,(T)0);
        return cimg::type<double>::nan();
      }

      static double mp_da_remove(_cimg_math_parser& mp) {
        mp_check_list(mp,"da_remove");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        CImg<T> &img = mp.imglist[ind];
        int siz = img?(int)cimg::float2uint(img[img._height - 1]):0;
        if (img && (img._width!=1 || img._depth!=1 || siz<0 || siz>img.height() - 1))
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'da_remove()': "
                                      "Specified image #%u of size (%d,%d,%d,%d) cannot be used as dynamic array%s.",
                                      mp.imgout.pixel_type(),ind,
                                      img.width(),img.height(),img.depth(),img.spectrum(),
                                      img._width==1 && img._depth==1?"":" (contains invalid element counter)");
        if (!siz)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'da_remove()': "
                                      "Dynamic array is empty.",
                                      mp.imgout.pixel_type());
        int
          start0 = mp.opcode[3]==~0U?siz - 1:_mp_arg(3),
          end0 = mp.opcode[4]==~0U?start0:_mp_arg(4),
          start = start0<0?start0 + siz:start0,
          end = end0<0?end0 + siz:end0;
        if (start<0 || start>=siz || end<0 || end>=siz || start>end)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'da_remove()': "
                                      "Invalid starting (%d) and ending (%d) positions "
                                      "(not ordered, in range -%d...%d).",
                                      mp.imgout.pixel_type(),start0,end0,siz,siz - 1);
        if (end<siz - 1) // Move remaining data in dynamic array
          cimg_forC(img,c) std::memmove(img.data(0,start,0,c),img.data(0,end + 1,0,c),(siz - 1 - end)*sizeof(T));
        siz-=end - start + 1;
        if (img.height()>32 && siz<img.height()/8) // Reduce size of dynamic array
          img.resize(1,std::max(2*siz + 1,32),1,-100,0);
        img[img._height - 1] = cimg::uint2float(siz,(T)0);
        return cimg::type<double>::nan();
      }

      static double mp_da_size(_cimg_math_parser& mp) {
        mp_check_list(mp,"da_size");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        CImg<T> &img = mp.imglist[ind];
        const int siz = img?(int)cimg::float2uint(img[img._height - 1]):0;
        if (img && (img._width!=1 || img._depth!=1 || siz<0 || siz>img.height() - 1))
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'da_size()': "
                                      "Specified image #%u of size (%d,%d,%d,%d) cannot be used as dynamic array%s.",
                                      mp.imgout.pixel_type(),ind,
                                      img.width(),img.height(),img.depth(),img.spectrum(),
                                      img._width==1 && img._depth==1?"":" (contains invalid element counter)");
        return siz;
      }

      static double mp_date(_cimg_math_parser& mp) {
        const unsigned int
          siz_out = (unsigned int)mp.opcode[2],
          siz_arg1 = (unsigned int)mp.opcode[4],
          siz_arg2 = (unsigned int)mp.opcode[6];
        double *ptr_out = &_mp_arg(1) + (siz_out?1:0);
        const double
          *ptr_arg1 = siz_arg1==~0U?0:&_mp_arg(3) + (siz_arg1?1:0),
          *ptr_arg2 = siz_arg2==~0U?0:&_mp_arg(5) + 1;

        if (!ptr_arg2) { // No filename specified
          if (!siz_arg1) return cimg::date((unsigned int)*ptr_arg1);
          if (siz_arg1==~0U) for (unsigned int k = 0; k<siz_out; ++k) ptr_out[k] = k;
          else for (unsigned int k = 0; k<siz_out; ++k) ptr_out[k] = ptr_arg1[k];
          cimg::date(ptr_out,siz_out);
          return cimg::type<double>::nan();
        }

        // Filename specified.
        CImg<charT> ss(siz_arg2 + 1);
        cimg_forX(ss,i) ss[i] = (char)ptr_arg2[i];
        ss.back() = 0;
        if (!siz_arg1) return cimg::fdate(ss,(unsigned int)*ptr_arg1);
        for (unsigned int k = 0; k<siz_out; ++k) ptr_out[k] = ptr_arg1[k];
        cimg::fdate(ss,ptr_out,siz_out);
        return cimg::type<double>::nan();
      }

      static double mp_debug(_cimg_math_parser& mp) {
        CImg<charT> expr(mp.opcode[2]);
        {
          const ulongT *ptrs = mp.opcode._data + 4;
          cimg_for(expr,ptrd,char) *ptrd = (char)*(ptrs++);
        }
        cimg::strellipsize(expr);
        const ulongT g_target = mp.opcode[1];

#if cimg_use_openmp==0
        const unsigned int n_thread = 0;
#else
        const unsigned int n_thread = omp_get_thread_num();
#endif
        cimg_pragma_openmp(critical(mp_debug)) {
          std::fprintf(cimg::output(),
                       "\n[" cimg_appname "_math_parser] %p[thread #%u]:%*c"
                       "Start debugging '%s', code length: %u -> mem[%u] (memsize: %u)",
                       (void*)&mp,n_thread,mp.debug_indent,' ',
                       expr._data,(unsigned int)mp.opcode[3],(unsigned int)g_target,mp.mem._width);
          std::fflush(cimg::output());
          mp.debug_indent+=3;
        }
        const CImg<ulongT> *const p_end = ++mp.p_code + mp.opcode[3];
        CImg<ulongT> _op;
        while (mp.p_code<p_end) {
          const CImg<ulongT> &op = *mp.p_code;
          mp.opcode._data = op._data;

          _op.assign(1,op._height - 1);
          const ulongT *ptrs = op._data + 1;
          for (ulongT *ptrd = _op._data, *const ptrde = _op._data + _op._height; ptrd<ptrde; ++ptrd)
            *ptrd = *(ptrs++);

          const ulongT target = mp.opcode[1];
          mp.eval(mp.p_code,mp.p_code + 1);

#define _mp_debug(name) fn==mp_##name?#name:
          const mp_func fn = (mp_func)*mp.opcode;
          const char *const s_fn =
            _mp_debug(abort) _mp_debug(abort) _mp_debug(abs) _mp_debug(abscut) _mp_debug(absmaxabs) _mp_debug(absminabs)
            _mp_debug(acos) _mp_debug(acosh) _mp_debug(add) _mp_debug(add_add) _mp_debug(add_mul) _mp_debug(add_sub)
            _mp_debug(arg0) _mp_debug(arg1) _mp_debug(argkth) _mp_debug(argmax) _mp_debug(argmax2) _mp_debug(argmaxabs)
            _mp_debug(argmaxabs2) _mp_debug(argmin) _mp_debug(argmin2) _mp_debug(argminabs) _mp_debug(argminabs2)
            _mp_debug(asin) _mp_debug(asinh) _mp_debug(atan) _mp_debug(atan2) _mp_debug(atanh) _mp_debug(avg)
            _mp_debug(avg2) _mp_debug(bitwise_and) _mp_debug(bitwise_left_shift) _mp_debug(bitwise_not)
            _mp_debug(bitwise_or) _mp_debug(bitwise_right_shift) _mp_debug(bitwise_xor) _mp_debug(bool) _mp_debug(break)
            _mp_debug(breakpoint) _mp_debug(c2o) _mp_debug(cbrt) _mp_debug(ceil) _mp_debug(complex_abs)
            _mp_debug(complex_conj) _mp_debug(complex_cos) _mp_debug(complex_cosh) _mp_debug(div_add) _mp_debug(div_div)
            _mp_debug(div_sub) _mp_debug(complex_div_sv) _mp_debug(complex_div_vv) _mp_debug(complex_exp)
            _mp_debug(complex_log) _mp_debug(complex_mul) _mp_debug(complex_one) _mp_debug(complex_pow_ss)
            _mp_debug(complex_pow_sv) _mp_debug(complex_pow_vs) _mp_debug(complex_pow_vv) _mp_debug(complex_sin)
            _mp_debug(complex_sinh) _mp_debug(complex_sqr) _mp_debug(complex_sqrt) _mp_debug(complex_tan)
            _mp_debug(complex_tanh) _mp_debug(continue) _mp_debug(convolve) _mp_debug(copy) _mp_debug(correlate)
            _mp_debug(cos) _mp_debug(cosh) _mp_debug(cov) _mp_debug(critical) _mp_debug(cross) _mp_debug(cumulate)
            _mp_debug(cumulate_ip) _mp_debug(cut) _mp_debug(da_back_or_pop) _mp_debug(da_freeze)
            _mp_debug(da_insert_or_push_n) _mp_debug(da_remove) _mp_debug(da_size) _mp_debug(date) _mp_debug(debug)
            _mp_debug(decrement) _mp_debug(deg2rad) _mp_debug(det) _mp_debug(diag) _mp_debug(div) _mp_debug(do)
            _mp_debug(dot) _mp_debug(echo) _mp_debug(ellipse) _mp_debug(epoch) _mp_debug(eq) _mp_debug(equalize)
            _mp_debug(equalize_ip) _mp_debug(erf) _mp_debug(erfinv) _mp_debug(exp) _mp_debug(expr) _mp_debug(eye)
            _mp_debug(f2ui) _mp_debug(factorial) _mp_debug(fft) _mp_debug(fibonacci) _mp_debug(find) _mp_debug(find_seq)
            _mp_debug(flood) _mp_debug(floor) _mp_debug(for) _mp_debug(frac) _mp_debug(fsize) _mp_debug(gamma)
            _mp_debug(gauss) _mp_debug(gcd) _mp_debug(gcd2) _mp_debug(get) _mp_debug(get) _mp_debug(gt) _mp_debug(gte)
            _mp_debug(histogram) _mp_debug(I) _mp_debug(i) _mp_debug(if) _mp_debug(IJoff) _mp_debug(ijoff)
            _mp_debug(IJxyz1) _mp_debug(IJxyz2) _mp_debug(IJxyz3) _mp_debug(ijxyzc1) _mp_debug(ijxyzc2)
            _mp_debug(ijxyzc3) _mp_debug(image_crop) _mp_debug(image_depth) _mp_debug(image_display)
            _mp_debug(image_draw) _mp_debug(image_find) _mp_debug(image_find_seq) _mp_debug(image_height)
            _mp_debug(image_is_shared) _mp_debug(image_print) _mp_debug(image_resize) _mp_debug(image_shift)
            _mp_debug(image_shift_ip) _mp_debug(image_spectrum) _mp_debug(image_stats) _mp_debug(image_stats_cm)
            _mp_debug(image_stats_cM) _mp_debug(image_stats_ia) _mp_debug(image_stats_ic)
            _mp_debug(image_stats_ic_static) _mp_debug(image_stats_id) _mp_debug(image_stats_id_static)
            _mp_debug(image_stats_im) _mp_debug(image_stats_iM) _mp_debug(image_stats_in) _mp_debug(image_stats_ip)
            _mp_debug(image_stats_is) _mp_debug(image_stats_static) _mp_debug(image_stats_xm) _mp_debug(image_stats_xM)
            _mp_debug(image_stats_ym) _mp_debug(image_stats_yM) _mp_debug(image_stats_zm) _mp_debug(image_stats_zM)
            _mp_debug(image_swap) _mp_debug(image_wh) _mp_debug(image_whd) _mp_debug(image_whds) _mp_debug(image_width)
            _mp_debug(increment) _mp_debug(index) _mp_debug(indexof) _mp_debug(inrange) _mp_debug(int) _mp_debug(isbool)
            _mp_debug(isdir) _mp_debug(isfile) _mp_debug(isfinite) _mp_debug(isin) _mp_debug(isinf) _mp_debug(isint)
            _mp_debug(isnan) _mp_debug(isvarname) _mp_debug(kth) _mp_debug(lcm) _mp_debug(lcm2) _mp_debug(lerp)
            _mp_debug(log) _mp_debug(log10) _mp_debug(log2) _mp_debug(logical_and) _mp_debug(logical_not)
            _mp_debug(logical_or) _mp_debug(logit) _mp_debug(lowercase) _mp_debug(lt) _mp_debug(lte) _mp_debug(map)
            _mp_debug(matrix_eigen) _mp_debug(matrix_invert) _mp_debug(matrix_mul) _mp_debug(matrix_qr)
            _mp_debug(matrix_svd) _mp_debug(max) _mp_debug(max2) _mp_debug(maxabs) _mp_debug(maxabs2) _mp_debug(med)
            _mp_debug(med2) _mp_debug(mem_copy) _mp_debug(mem_display) _mp_debug(min) _mp_debug(min2) _mp_debug(minabs)
            _mp_debug(minabs2) _mp_debug(minus) _mp_debug(mirror) _mp_debug(mirror_ip) _mp_debug(modulo)
            _mp_debug(mproj) _mp_debug(mse) _mp_debug(mul) _mp_debug(mul_div) _mp_debug(mul_mul) _mp_debug(mul_sub)
            _mp_debug(name) _mp_debug(name) _mp_debug(neq) _mp_debug(noise) _mp_debug(noise_ip) _mp_debug(normalize)
            _mp_debug(normalize_ip) _mp_debug(normp) _mp_debug(o2c) _mp_debug(permutations) _mp_debug(permute)
            _mp_debug(permute_ip) _mp_debug(polygon) _mp_debug(pow) _mp_debug(pow0_25) _mp_debug(pow3) _mp_debug(pow4)
            _mp_debug(print) _mp_debug(prod) _mp_debug(prod2) _mp_debug(rad2deg) _mp_debug(rand_double)
            _mp_debug(rand_double_0_1) _mp_debug(rand_double_0_N) _mp_debug(rand_double_ext)
            _mp_debug(rand_double_gaussian) _mp_debug(rand_double_m1_1) _mp_debug(rand_int) _mp_debug(rand_int_0_1)
            _mp_debug(rand_int_0_N) _mp_debug(rand_int_ext) _mp_debug(rand_int_m1_1) _mp_debug(repeat)
            _mp_debug(reverse) _mp_debug(reverse_ip) _mp_debug(rol) _mp_debug(ror) _mp_debug(rot2d) _mp_debug(rot3d)
            _mp_debug(round) _mp_debug(run) _mp_debug(s2v) _mp_debug(self_add) _mp_debug(self_bitwise_and)
            _mp_debug(self_bitwise_left_shift) _mp_debug(self_bitwise_or) _mp_debug(self_bitwise_right_shift)
            _mp_debug(self_decrement) _mp_debug(self_div) _mp_debug(self_increment) _mp_debug(self_modulo)
            _mp_debug(self_mul) _mp_debug(self_pow) _mp_debug(self_sub) _mp_debug(self_vector_add_s)
            _mp_debug(self_vector_add_v) _mp_debug(self_vector_bitwise_and_s) _mp_debug(self_vector_bitwise_and_v)
            _mp_debug(self_vector_bitwise_left_shift_s) _mp_debug(self_vector_bitwise_left_shift_v)
            _mp_debug(self_vector_bitwise_or_s) _mp_debug(self_vector_bitwise_or_v)
            _mp_debug(self_vector_bitwise_right_shift_s) _mp_debug(self_vector_bitwise_right_shift_v)
            _mp_debug(self_vector_decrement) _mp_debug(self_vector_div_s) _mp_debug(self_vector_div_v)
            _mp_debug(self_vector_increment) _mp_debug(self_vector_modulo_s) _mp_debug(self_vector_modulo_v)
            _mp_debug(self_vector_mul_s) _mp_debug(self_vector_mul_v) _mp_debug(self_vector_pow_s)
            _mp_debug(self_vector_pow_v) _mp_debug(self_vector_sub_s) _mp_debug(self_vector_sub_v) _mp_debug(set)
            _mp_debug(set) _mp_debug(set_ijoff) _mp_debug(set_IJoff_s) _mp_debug(set_IJoff_v) _mp_debug(set_IJxyz_s)
            _mp_debug(set_IJxyz_v) _mp_debug(set_ijxyzc)_mp_debug(shift) _mp_debug(shift_ip)
            _mp_debug(sigmoid) _mp_debug(sign) _mp_debug(sin)
            _mp_debug(sinc) _mp_debug(sinh) _mp_debug(size_list) _mp_debug(softargmax) _mp_debug(softargmin)
            _mp_debug(softmax) _mp_debug(softmin) _mp_debug(solve) _mp_debug(sort) _mp_debug(sort_ip) _mp_debug(sqr)
            _mp_debug(sqrt) _mp_debug(srand) _mp_debug(srand0) _mp_debug(std) _mp_debug(std2) _mp_debug(store)
            _mp_debug(store) _mp_debug(string) _mp_debug(string_init) _mp_debug(sub) _mp_debug(sub_div)
            _mp_debug(sub_mul) _mp_debug(sub_sub) _mp_debug(sum) _mp_debug(sum2) _mp_debug(swap) _mp_debug(tan)
            _mp_debug(tanh) _mp_debug(trace) _mp_debug(transpose) _mp_debug(ui2f) _mp_debug(unitnorm)
            _mp_debug(uppercase) _mp_debug(v2s) _mp_debug(var) _mp_debug(var2) _mp_debug(vargkth) _mp_debug(vargmax)
            _mp_debug(vargmaxabs) _mp_debug(vargmin) _mp_debug(vargminabs) _mp_debug(vavg) _mp_debug(vector_abs)
            _mp_debug(vector_abscut) _mp_debug(vector_acos) _mp_debug(vector_acosh) _mp_debug(vector_add_sv)
            _mp_debug(vector_add_vs) _mp_debug(vector_add_vv) _mp_debug(vector_asin) _mp_debug(vector_asinh)
            _mp_debug(vector_atan) _mp_debug(vector_atan2_sv) _mp_debug(vector_atan2_vs) _mp_debug(vector_atan2_vv)
            _mp_debug(vector_atanh) _mp_debug(vector_bitwise_not) _mp_debug(vector_bitwise_and_sv)
            _mp_debug(vector_bitwise_and_vs) _mp_debug(vector_bitwise_and_vv) _mp_debug(vector_bitwise_left_shift_sv)
            _mp_debug(vector_bitwise_left_shift_vs) _mp_debug(vector_bitwise_left_shift_vv)
            _mp_debug(vector_bitwise_or_sv) _mp_debug(vector_bitwise_or_vs) _mp_debug(vector_bitwise_or_vv)
            _mp_debug(vector_bitwise_right_shift_sv) _mp_debug(vector_bitwise_right_shift_vs)
            _mp_debug(vector_bitwise_right_shift_vv) _mp_debug(vector_bitwise_xor_sv) _mp_debug(vector_bitwise_xor_vs)
            _mp_debug(vector_bitwise_xor_vv) _mp_debug(vector_bool) _mp_debug(vector_cbrt) _mp_debug(vector_ceil)
            _mp_debug(vector_copy) _mp_debug(vector_cos) _mp_debug(vector_cosh) _mp_debug(vector_crop)
            _mp_debug(vector_crop_ext) _mp_debug(vector_cut) _mp_debug(vector_deg2rad) _mp_debug(vector_display)
            _mp_debug(vector_div_sv) _mp_debug(vector_div_vs) _mp_debug(vector_div_vv) _mp_debug(vector_draw)
            _mp_debug(vector_eq) _mp_debug(vector_erf) _mp_debug(vector_erfinv) _mp_debug(vector_exp)
            _mp_debug(vector_f2ui) _mp_debug(vector_factorial) _mp_debug(vector_fibonacci) _mp_debug(vector_fill)
            _mp_debug(vector_fill_ext) _mp_debug(vector_floor) _mp_debug(vector_frac) _mp_debug(vector_gamma)
            _mp_debug(vector_gauss) _mp_debug(vector_gt_sv) _mp_debug(vector_gt_vs) _mp_debug(vector_gt_vv)
            _mp_debug(vector_gte_sv) _mp_debug(vector_gte_vs) _mp_debug(vector_gte_vv) _mp_debug(vector_hypot)
            _mp_debug(vector_init) _mp_debug(vector_int) _mp_debug(vector_isbool) _mp_debug(vector_isfinite)
            _mp_debug(vector_isinf) _mp_debug(vector_isint) _mp_debug(vector_isnan) _mp_debug(vector_lerp)
            _mp_debug(vector_log) _mp_debug(vector_log10) _mp_debug(vector_log2) _mp_debug(vector_logical_not)
            _mp_debug(vector_logit) _mp_debug(vector_lowercase) _mp_debug(vector_lt_sv) _mp_debug(vector_lt_vs)
            _mp_debug(vector_lt_vv) _mp_debug(vector_lte_sv) _mp_debug(vector_lte_vs) _mp_debug(vector_lte_vv)
            _mp_debug(vector_modulo_sv) _mp_debug(vector_modulo_vs) _mp_debug(vector_modulo_vv) _mp_debug(vector_mul_sv)
            _mp_debug(vector_mul_vs) _mp_debug(vector_mul_vv) _mp_debug(vector_neq) _mp_debug(vector_minus)
            _mp_debug(vector_norm0) _mp_debug(vector_norm1) _mp_debug(vector_norm2) _mp_debug(vector_norminf)
            _mp_debug(vector_off) _mp_debug(vector_pow_sv) _mp_debug(vector_pow_vs) _mp_debug(vector_pow_vv)
            _mp_debug(vector_print) _mp_debug(vector_rad2deg) _mp_debug(vector_rand) _mp_debug(vector_rand_double_ext)
            _mp_debug(vector_rand_double_sv) _mp_debug(vector_rand_double_vs) _mp_debug(vector_rand_double_vv)
            _mp_debug(vector_rand_int_sv) _mp_debug(vector_rand_int_ext) _mp_debug(vector_rand_int_vs)
            _mp_debug(vector_rand_int_vv) _mp_debug(vector_resize) _mp_debug(vector_resize_ext) _mp_debug(vector_rol_sv)
            _mp_debug(vector_rol_vs) _mp_debug(vector_rol_vv) _mp_debug(vector_ror_sv) _mp_debug(vector_ror_vs)
            _mp_debug(vector_ror_vv) _mp_debug(vector_round) _mp_debug(vector_set_off)
            _mp_debug(vector_sigmoid) _mp_debug(vector_sign) _mp_debug(vector_sin)
            _mp_debug(vector_sinc) _mp_debug(vector_sinh) _mp_debug(vector_sqr) _mp_debug(vector_sqrt)
            _mp_debug(vector_stats) _mp_debug(vector_sub_sv) _mp_debug(vector_sub_vs) _mp_debug(vector_sub_vv)
            _mp_debug(vector_tan) _mp_debug(vector_tanh) _mp_debug(vector_ui2f) _mp_debug(vector_uppercase)
            _mp_debug(vector_wave_sv) _mp_debug(vector_wave_vs) _mp_debug(vector_wave_vv) _mp_debug(vkth)
            _mp_debug(vmax) _mp_debug(vmaxabs) _mp_debug(vmedian) _mp_debug(vmin) _mp_debug(vminabs) _mp_debug(vprod)
            _mp_debug(vstd) _mp_debug(vsum) _mp_debug(vvar) _mp_debug(warp) _mp_debug(wave) _mp_debug(while) "unknown";

          cimg_pragma_openmp(critical(mp_debug)) {
            std::fprintf(cimg::output(),
                         "\n[" cimg_appname "_math_parser] %p[thread #%u]:%*c"
                         "Opcode %p = [ %p (%s),%s ] -> mem[%u] = %.17g",
                         (void*)&mp,n_thread,mp.debug_indent,' ',
                         (void*)mp.opcode._data,(void*)*mp.opcode,s_fn,_op.value_string().data(),
                         (unsigned int)target,mp.mem[target]);
            std::fflush(cimg::output());
          }
        }
        cimg_pragma_openmp(critical(mp_debug)) {
          mp.debug_indent-=3;
          std::fprintf(cimg::output(),
                       "\n[" cimg_appname "_math_parser] %p[thread #%u]:%*c"
                       "End debugging '%s' -> mem[%u] = %.17g (memsize: %u)",
                       (void*)&mp,n_thread,mp.debug_indent,' ',
                       expr._data,(unsigned int)g_target,mp.mem[g_target],mp.mem._width);
          std::fflush(cimg::output());
        }
        --mp.p_code;
        return mp.mem[g_target];
      }

      static double mp_decrement(_cimg_math_parser& mp) {
        return _mp_arg(2) - 1;
      }

      static double mp_det(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int k = (unsigned int)mp.opcode[3];
        return CImg<doubleT>(ptrs,k,k,1,1,true).det();
      }

      static double mp_diag(_cimg_math_parser& mp) {
        const unsigned int siz = mp.opcode[2], i_end = siz + 3;
        double *ptrd = &_mp_arg(1) + 1;
        std::memset(ptrd,0,siz*siz*sizeof(double));
        for (unsigned int i = 3; i<i_end; ++i) { *(ptrd++) = _mp_arg(i); ptrd+=siz; }
        return cimg::type<double>::nan();
      }

      static double mp_div_add(_cimg_math_parser& mp) {
        return _mp_arg(2)/_mp_arg(3) + _mp_arg(4);
      }

      static double mp_div_div(_cimg_math_parser& mp) {
        return _mp_arg(2)/_mp_arg(3)/_mp_arg(4);
      }

      static double mp_div_sub(_cimg_math_parser& mp) {
        return _mp_arg(2)/_mp_arg(3) - _mp_arg(4);
      }

      static double mp_do(_cimg_math_parser& mp) {
        const ulongT
          mem_body = mp.opcode[1],
          mem_cond = mp.opcode[2];
        const CImg<ulongT>
          *const p_body = ++mp.p_code,
          *const p_cond = p_body + mp.opcode[3],
          *const p_end = p_cond + mp.opcode[4];
        const unsigned int siz = (unsigned int)mp.opcode[5];
        if (mp.opcode[6]) { // Set default value for result and condition if necessary
          if (siz) CImg<doubleT>(&mp.mem[mem_body] + 1,siz,1,1,1,true).fill(cimg::type<double>::nan());
          else mp.mem[mem_body] = cimg::type<double>::nan();
        }
        if (mp.opcode[7]) mp.mem[mem_cond] = 0;
        const unsigned int _break_type = mp.break_type;
        mp.break_type = 0;
        do {
          mp.eval(p_body,p_cond); // Evaluate body
          if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
          mp.eval(p_cond,p_end); // Evaluate condition
          if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
        } while (mp.mem[mem_cond]);
        mp.break_type = _break_type;
        mp.p_code = p_end - 1;
        return mp.mem[mem_body];
      }

      static double mp_dot(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[4];
        return CImg<doubleT>(&_mp_arg(2) + 1,1,siz,1,1,true).
          dot(CImg<doubleT>(&_mp_arg(3) + 1,1,siz,1,1,true));
      }

      static double mp_echo(_cimg_math_parser& mp) {
        const unsigned int nb_args = (unsigned int)mp.opcode[2];
        if (!nb_args) { std::fputc('\n',cimg::output()); return cimg::type<double>::nan(); } // No arguments
        CImgList<charT> _str;
        CImg<charT> it;
        for (unsigned int n = 0; n<nb_args; ++n) {
          const unsigned int siz = (unsigned int)mp.opcode[4 + 2*n];
          if (siz) { // Vector argument -> string
            const double *ptr = &_mp_arg(3 + 2*n) + 1;
            unsigned int l = 0;
            while (l<siz && ptr[l]) ++l;
            CImg<doubleT>(ptr,l,1,1,1,true).move_to(_str);
          } else { // Scalar argument -> number
            it.assign(24);
            cimg_snprintf(it,it._width,"%.17g",_mp_arg(3 + 2*n));
            CImg<charT>::string(it,false,true).move_to(_str);
          }
        }
        CImg(1,1,1,1,0).move_to(_str);
        const CImg<charT> str = _str>'x';
        std::fprintf(cimg::output(),"\n%s",str._data);
        return cimg::type<double>::nan();
      }

      static double mp_ellipse(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        unsigned int ind = (unsigned int)mp.opcode[3];
        if (ind!=~0U) {
          mp_check_list(mp,"ellipse");
          ind = (unsigned int)cimg::mod((int)_mp_arg(3),mp.imglist.width());
        }
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        CImg<T> color(img._spectrum,1,1,1,0);
        bool is_invalid_arguments = false, is_outlined = false;
        float r1 = 0, r2 = 0, angle = 0, opacity = 1;
        unsigned int i = 4, pattern = ~0U;
        int x0 = 0, y0 = 0;
        if (i>=i_end) is_invalid_arguments = true;
        else {
          x0 = (int)cimg::round(_mp_arg(i++));
          if (i>=i_end) is_invalid_arguments = true;
          else {
            y0 = (int)cimg::round(_mp_arg(i++));
            if (i>=i_end) is_invalid_arguments = true;
            else {
              r1 = (float)_mp_arg(i++);
              if (i>=i_end) r2 = r1;
              else {
                r2 = (float)_mp_arg(i++);
                if (i<i_end) {
                  angle = (float)(_mp_arg(i++)*180/cimg::PI);
                  if (i<i_end) {
                    opacity = (float)_mp_arg(i++);
                    if (r1<0 && r2<0) {
                      pattern = (unsigned int)_mp_arg(i++);
                      is_outlined = true;
                      r1 = -r1; r2 = -r2;
                    }
                    if (i<i_end) {
                      cimg_forX(color,k) if (i<i_end) color[k] = (T)_mp_arg(i++);
                      else { color.resize(k,1,1,1,-1); break; }
                      color.resize(img._spectrum,1,1,1,0,2);
                    }
                  }
                }
              }
            }
          }
        }
        if (!is_invalid_arguments) {
          if (is_outlined) img.draw_ellipse(x0,y0,r1,r2,angle,color._data,opacity,pattern);
          else img.draw_ellipse(x0,y0,r1,r2,angle,color._data,opacity);
        } else {
          CImg<doubleT> args(i_end - 4);
          cimg_forX(args,k) args[k] = _mp_arg(4 + k);
          if (ind==~0U)
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'ellipse()': "
                                        "Invalid arguments '%s'. ",
                                        mp.imgin.pixel_type(),args.value_string()._data);
          else
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'ellipse()': "
                                        "Invalid arguments '#%u%s%s'. ",
                                        mp.imgin.pixel_type(),ind,args._width?",":"",args.value_string()._data);
        }
        return cimg::type<double>::nan();
      }

      static double mp_epoch(_cimg_math_parser& mp) {
        unsigned int
          year = (unsigned int)mp.opcode[2]==~0U?~0U:(unsigned int)std::max(_mp_arg(2),1900.),
          month = (unsigned int)mp.opcode[3]==~0U?~0U:(unsigned int)cimg::cut(_mp_arg(3),1.,12.),
          day = (unsigned int)mp.opcode[4]==~0U?~0U:(unsigned int)cimg::cut(_mp_arg(4),1.,31.),
          hour = (unsigned int)mp.opcode[5]==~0U?~0U:(unsigned int)cimg::cut(_mp_arg(5),0.,23.),
          minute = (unsigned int)mp.opcode[6]==~0U?~0U:(unsigned int)cimg::cut(_mp_arg(6),0.,59.),
          second = (unsigned int)mp.opcode[7]==~0U?~0U:(unsigned int)cimg::cut(_mp_arg(7),0.,60.);
        if (year==~0U && month==~0U && day==~0U &&
            hour==~0U && minute==~0U && second==~0U) // No argument -> current date
          return (double)cimg::epoch(cimg::date(0),cimg::date(1),cimg::date(2),
                                     cimg::date(4),cimg::date(5),cimg::date(6));
        if (year==~0U) year = (unsigned int)cimg::date(0);
        if (month==~0U) month = 1U;
        if (day==~0U) day = 1U;
        if (hour==~0U) hour = 0U;
        if (minute==~0U) minute = 0U;
        if (second==~0U) second = 0U;
        return (double)cimg::epoch((int)year,(int)month,(int)day,(int)hour,(int)minute,(int)second);
      }

      static double mp_eq(_cimg_math_parser& mp) {
        return (double)(_mp_arg(2)==_mp_arg(3));
      }

      static double mp_equalize(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          siz = (unsigned int)mp.opcode[3],
          nb_levels = (unsigned int)mp.opcode[4];
        const double *const ptrs = &_mp_arg(2) + 1;
        CImg<doubleT> img(ptrs,siz,1,1,1,true);
        double min_value = 0, max_value = 0;
        if ((unsigned int)mp.opcode[5]==~0U || (unsigned int)mp.opcode[6]==~0U)
          min_value = img.min_max(max_value);
        if ((unsigned int)mp.opcode[5]!=~0U) min_value = _mp_arg(5);
        if ((unsigned int)mp.opcode[6]!=~0U) max_value = _mp_arg(6);
        CImg<doubleT>(ptrd,siz,1,1,1,true) = img.get_equalize(nb_levels,min_value,max_value);
        return cimg::type<double>::nan();
      }

      static double mp_equalize_ip(_cimg_math_parser& mp) { // In-place version
        const unsigned int
          siz = (unsigned int)mp.opcode[3],
          nb_levels = (unsigned int)mp.opcode[4];
        double *const ptrs = &_mp_arg(2) + 1;
        CImg<doubleT> img(ptrs,siz,1,1,1,true);
        double min_value = 0, max_value = 0;
        if ((unsigned int)mp.opcode[5]==~0U || (unsigned int)mp.opcode[6]==~0U)
          min_value = img.min_max(max_value);
        if ((unsigned int)mp.opcode[5]!=~0U) min_value = _mp_arg(5);
        if ((unsigned int)mp.opcode[6]!=~0U) max_value = _mp_arg(6);
        img.equalize(nb_levels,min_value,max_value);
        return cimg::type<double>::nan();
      }

      static double mp_expr(_cimg_math_parser& mp) {
        const unsigned int
          sizs = (unsigned int)mp.opcode[3],
          w = (unsigned int)mp.opcode[4],
          h = (unsigned int)mp.opcode[5],
          d = (unsigned int)mp.opcode[6],
          s = (unsigned int)mp.opcode[7],
          A = (unsigned int)mp.opcode[8],
          sA = (unsigned int)mp.opcode[9];
        const double
          *ptrs = &_mp_arg(2) + 1,
          *ptrA = A==~0U?0:&_mp_arg(8) + 1;
        double *ptrd = &_mp_arg(1) + 1;
        CImg<charT> ss(sizs + 1);
        cimg_for_inX(ss,0,ss.width() - 2,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        if (ptrA) {
          CImg<doubleT>
            out(ptrd,w,h,d,s,true),
            in = CImg<doubleT>(ptrA,w,h,d,sA);
          if (sA<s) in.channels(0,s - 1);
          in._fill(ss,true,3,&mp.imglist,"mp_expr",0,0);
          if (sA==s) out = in; else out.draw_image(in);
        } else
          CImg<doubleT>(ptrd,w,h,d,s,true) = CImg<doubleT>(w,h,d,s,0).
            _fill(ss,true,3,&mp.imglist,"mp_expr",0,0);
        return cimg::type<double>::nan();
      }

      static double mp_eye(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int k = (unsigned int)mp.opcode[2];
        CImg<doubleT>(ptrd,k,k,1,1,true).identity_matrix();
        return cimg::type<double>::nan();
      }

      static double mp_find(_cimg_math_parser& mp) {
        const int _step = (int)_mp_arg(6), step = _step?_step:-1;
        const ulongT siz = (ulongT)mp.opcode[3];
        longT ind = (longT)(mp.opcode[5]!=_cimg_mp_slot_nan?_mp_arg(5):step>0?0:siz - 1);
        if (ind<0 || ind>=(longT)siz) return -1.;
        const double
          *const ptrb = &_mp_arg(2) + 1,
          *const ptre = ptrb + siz,
          val = _mp_arg(4),
          *ptr = ptrb + ind;

        // Forward search.
        if (step>0) {
          if (cimg::type<double>::is_nan(val))
            while (ptr<ptre && !cimg::type<double>::is_nan(*ptr)) ptr+=step;
          else
            while (ptr<ptre && *ptr!=val) ptr+=step;
          return ptr>=ptre?-1.:(double)(ptr - ptrb);
        }

        // Backward search.
        if (cimg::type<double>::is_nan(val))
          while (ptr>=ptrb && !cimg::type<double>::is_nan(*ptr)) ptr+=step;
        else
          while (ptr>=ptrb && *ptr!=val) ptr+=step;
        return ptr<ptrb?-1.:(double)(ptr - ptrb);
      }

      static double mp_find_seq(_cimg_math_parser& mp) {
        const int _step = (int)_mp_arg(7), step = _step?_step:-1;
        const ulongT
          siz1 = (ulongT)mp.opcode[3],
          siz2 = (ulongT)mp.opcode[5];
        longT ind = (longT)(mp.opcode[6]!=_cimg_mp_slot_nan?_mp_arg(6):step>0?0:siz1 - 1);
        if (ind<0 || ind>=(longT)siz1) return -1.;
        const double
          *const ptr1b = &_mp_arg(2) + 1,
          *const ptr1e = ptr1b + siz1,
          *const ptr2b = &_mp_arg(4) + 1,
          *const ptr2e = ptr2b + siz2,
          *ptr1 = ptr1b + ind,
          *p1 = 0,
          *p2 = 0;

        // Forward search.
        if (step>0) {
          do {
            if (cimg::type<double>::is_nan(*ptr2b))
              while (ptr1<ptr1e && !cimg::type<double>::is_nan(*ptr1)) ptr1+=step;
            else
              while (ptr1<ptr1e && *ptr1!=*ptr2b) ptr1+=step;
            if (ptr1>=ptr1e) return -1.;
            p1 = ptr1 + 1;
            p2 = ptr2b + 1;
            while (p1<ptr1e && p2<ptr2e &&
                   ((cimg::type<double>::is_nan(*p1) && cimg::type<double>::is_nan(*p2)) || *p1==*p2)) { ++p1; ++p2; }
          } while (p2<ptr2e && (ptr1+=step)<ptr1e);
          return p2<ptr2e?-1.:(double)(ptr1 - ptr1b);
        }

        // Backward search.
        do {
          if (cimg::type<double>::is_nan(*ptr2b))
            while (ptr1>=ptr1b && !cimg::type<double>::is_nan(*ptr1)) ptr1+=step;
          else
            while (ptr1>=ptr1b && *ptr1!=*ptr2b) ptr1+=step;
          if (ptr1<ptr1b) return -1.;
          p1 = ptr1 + 1;
          p2 = ptr2b + 1;
          while (p1<ptr1e && p2<ptr2e &&
                 ((cimg::type<double>::is_nan(*p1) && cimg::type<double>::is_nan(*p2)) || *p1==*p2)) { ++p1; ++p2; }
        } while (p2<ptr2e && (ptr1+=step)>=ptr1b);
        return p2<ptr2e?-1.:(double)(ptr1 - ptr1b);
      }

      static double mp_fft(_cimg_math_parser& mp) {
        const bool is_ifft = (bool)mp.opcode[2];
        double *const ptr_r = &_mp_arg(3) + 1, *const ptr_i = &_mp_arg(4) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[5],
          h = (unsigned int)mp.opcode[6],
          d = (unsigned int)mp.opcode[7],
          s = (unsigned int)mp.opcode[8];
        unsigned int
          sa = (unsigned int)mp.opcode[10];
        const double *const axes = &_mp_arg(9) + (sa?1:0);
        if (!sa) ++sa;
        CImgList<doubleT> pair(2);
        pair[0].assign(ptr_r,w,h,d,s,true); // Real part
        pair[1].assign(ptr_i,w,h,d,s,true); // Imaginary part
        if (*axes) for (unsigned int k = 0; k<sa; ++k) {
            const double axis = axes[k];
            if (axis=='x' || axis=='y' || axis=='z') pair.FFT(axis,is_ifft);
            else {
              CImg<char> str(sa + 1); str.get_shared_points(0,sa - 1) = CImg<double>(axes,sa); str.back() = 0;
              throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function mp_%s()': "
                                          "Invalid specified axes '%s' (should contain only 'x','y' or 'z').",
                                          mp.imgout.pixel_type(),is_ifft?"ifft":"fft",
                                          str._data);
            }
          } else pair.FFT(is_ifft);
        return cimg::type<double>::nan();
      }

      static double mp_flood(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        unsigned int ind = (unsigned int)mp.opcode[3];
        if (ind!=~0U) {
          mp_check_list(mp,"flood");
          ind = (unsigned int)cimg::mod((int)_mp_arg(3),mp.imglist.width());
        }
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        CImg<T> color(img._spectrum,1,1,1,0);
        bool is_high_connectivity = false;
        float tolerance = 0, opacity = 1;
        int x0 = 0, y0 = 0, z0 = 0;
        unsigned int i = 4;
        if (i<i_end) {
          x0 = (int)cimg::round(_mp_arg(i++));
          if (i<i_end) {
            y0 = (int)cimg::round(_mp_arg(i++));
            if (i<i_end) {
              z0 = (int)cimg::round(_mp_arg(i++));
              if (i<i_end) {
                tolerance = (float)_mp_arg(i++);
                if (i<i_end) {
                  is_high_connectivity = (bool)_mp_arg(i++);
                  if (i<i_end) {
                    opacity = (float)_mp_arg(i++);
                    if (i<i_end) {
                      cimg_forX(color,k) if (i<i_end) color[k] = (T)_mp_arg(i++);
                      else { color.resize(k,1,1,1,-1); break; }
                      color.resize(img._spectrum,1,1,1,0,2);
                    }
                  }
                }
              }
            }
          }
        }
        img.draw_fill(x0,y0,z0,color._data,opacity,tolerance,is_high_connectivity);
        return cimg::type<double>::nan();
      }

      static double mp_for(_cimg_math_parser& mp) {
        const ulongT
          mem_body = mp.opcode[1],
          mem_cond = mp.opcode[3];
        const CImg<ulongT>
          *const p_init = ++mp.p_code,
          *const p_cond = p_init + mp.opcode[4],
          *const p_body = p_cond + mp.opcode[5],
          *const p_post = p_body + mp.opcode[6],
          *const p_end = p_post + mp.opcode[7];
        const unsigned int siz = (unsigned int)mp.opcode[2];
        bool is_cond = false;
        if (mp.opcode[8]) { // Set default value for result and condition if necessary
          if (siz) CImg<doubleT>(&mp.mem[mem_body] + 1,siz,1,1,1,true).fill(cimg::type<double>::nan());
          else mp.mem[mem_body] = cimg::type<double>::nan();
        }
        if (mp.opcode[9]) mp.mem[mem_cond] = 0;
        const unsigned int _break_type = mp.break_type;
        mp.break_type = 0;
        mp.eval(p_init,p_cond); // Evaluate init
        if (!mp.break_type) do {
            mp.eval(p_cond,p_body); // Evaluate condition
            if (mp.break_type==1) break;
            is_cond = (bool)mp.mem[mem_cond];
            if (is_cond && !mp.break_type) {
              mp.eval(p_body,p_post); // Evaluate body
              if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
              mp.eval(p_post,p_end); // Evaluate post-code
              if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
            }
          } while (is_cond);

        mp.break_type = _break_type;
        mp.p_code = p_end - 1;
        return mp.mem[mem_body];
      }

      static double mp_fsize(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(2) + 1;
        const ulongT siz = (ulongT)mp.opcode[3];
        CImg<charT> ss(siz + 1);
        cimg_forX(ss,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        return (double)cimg::fsize(ss);
      }

      static double mp_gauss(_cimg_math_parser& mp) {
        const double x = _mp_arg(2), sigma = _mp_arg(3), sigma2 = sigma*sigma;
        const bool is_normalized = (bool)_mp_arg(4);
        return std::exp(-cimg::sqr(x)/(2*sigma2))/(is_normalized?std::sqrt(2*sigma2*cimg::PI):1);
      }

      static double mp_vector_gauss(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const double *const ptrs = &_mp_arg(3) + 1, sigma = _mp_arg(4), sigma2 = sigma*sigma;
        const bool is_normalized = (bool)_mp_arg(5);
        for (unsigned int k = 0; k<siz; ++k)
          ptrd[k] = (double)std::exp(-cimg::sqr(ptrs[k])/(2*sigma2))/(is_normalized?std::sqrt(2*sigma2*cimg::PI):1);
        return cimg::type<double>::nan();
      }

      static double mp_gcd(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        CImg<cimg_int64> values;
        if (i_end==5) { // Only a single argument
          if ((unsigned)mp.opcode[4]==1) return _mp_arg(3); // Real value
          else values.assign(&_mp_arg(3),(unsigned int)mp.opcode[4]); // Vector value
        } else if (i_end==7 && (unsigned int)mp.opcode[4]==1 && (unsigned int)mp.opcode[6]==1) // Two real arguments
          return (double)cimg::gcd((cimg_int64)_mp_arg(3),(cimg_int64)_mp_arg(5));
        else {
          unsigned int siz = 0;
          for (unsigned int i = 4; i<i_end; i+=2) siz+=(unsigned int)mp.opcode[i];
          values.assign(siz);
          cimg_int64 *ptr = values;
          for (unsigned int i = 3; i<i_end; i+=2) {
            const unsigned int len = (unsigned int)mp.opcode[i + 1];
            double *ptrs = &_mp_arg(i);
            if (len>1) for (unsigned int k = 0; k<len; ++k) *(ptr++) = (cimg_int64)ptrs[k];
            else *(ptr++) = (cimg_int64)_mp_arg(i);
          }
        }
        return values.gcd();
      }

      static double mp_gcd2(_cimg_math_parser& mp) {
        return (double)cimg::gcd((cimg_int64)_mp_arg(2),(cimg_int64)_mp_arg(3));
      }

#ifdef cimg_mp_func_get
      static double mp_get(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(2) + 1;
        double *ptrd = &_mp_arg(1);
        const unsigned int
          sizs = (unsigned int)mp.opcode[3],
          sizd = (unsigned int)mp.opcode[4];
        const bool to_string = (bool)mp.opcode[5];
        CImg<charT> ss(sizs + 1);
        cimg_for_inX(ss,0,ss.width() - 2,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        if (sizd) cimg_mp_func_get(ptrd + 1,sizd,to_string,ss._data);
        else cimg_mp_func_get(ptrd,0,to_string,ss._data);
        return cimg::type<double>::nan();
      }
#else
      static double mp_get(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_histogram(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          siz = (unsigned int)mp.opcode[3],
          nb_levels = (unsigned int)mp.opcode[4];
        const double *const ptrs = &_mp_arg(2) + 1;
        CImg<doubleT> img(ptrs,siz,1,1,1,true);
        double min_value = 0, max_value = 0;
        if ((unsigned int)mp.opcode[5]==~0U || (unsigned int)mp.opcode[6]==~0U)
          min_value = img.min_max(max_value);
        if ((unsigned int)mp.opcode[5]!=~0U) min_value = _mp_arg(5);
        if ((unsigned int)mp.opcode[6]!=~0U) max_value = _mp_arg(6);
        CImg<doubleT>(ptrd,nb_levels,1,1,1,true) = img.get_histogram(nb_levels,min_value,max_value);
        return cimg::type<double>::nan();
      }

      static double mp_i(_cimg_math_parser& mp) {
        if (mp.imgin)
          return (double)mp.imgin((int)mp.mem[_cimg_mp_slot_x],(int)mp.mem[_cimg_mp_slot_y],
                                  (int)mp.mem[_cimg_mp_slot_z],(int)mp.mem[_cimg_mp_slot_c]);
        return 0;
      }

      static double mp_if(_cimg_math_parser& mp) {
        const bool is_cond = (bool)_mp_arg(2);
        const ulongT
          mem_left = mp.opcode[3],
          mem_right = mp.opcode[4];
        const CImg<ulongT>
          *const p_right = ++mp.p_code + mp.opcode[5],
          *const p_end = p_right + mp.opcode[6];
        const unsigned int vtarget = (unsigned int)mp.opcode[1], siz = (unsigned int)mp.opcode[7];
        if (is_cond) mp.eval(mp.p_code,p_right); else mp.eval(p_right,p_end);
        if (mp.p_code==mp.p_break) --mp.p_code; else mp.p_code = p_end - 1;
        if (siz) std::memcpy(&mp.mem[vtarget] + 1,&mp.mem[is_cond?mem_left:mem_right] + 1,sizeof(double)*siz);
        return mp.mem[is_cond?mem_left:mem_right];
      }

      static double mp_ijoff(_cimg_math_parser& mp) {
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          boundary_conditions = (unsigned int)_mp_arg(5);
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const longT
          off = (longT)(is_relative?img.offset((int)mp.mem[_cimg_mp_slot_x],
                                               (int)mp.mem[_cimg_mp_slot_y],
                                               (int)mp.mem[_cimg_mp_slot_z],
                                               (int)mp.mem[_cimg_mp_slot_c]) + _mp_arg(4):_mp_arg(4)),
          whds = (longT)img.size();
        if (off>=0 && off<whds) return (double)img[off];
        if (img._data) switch (boundary_conditions) {
          case 3 : { // Mirror
            const longT whds2 = 2*whds, moff = cimg::mod(off,whds2);
            return (double)img[moff<whds?moff:whds2 - moff - 1];
          }
          case 2 : // Periodic
            return (double)img[cimg::mod(off,whds)];
          case 1 : // Neumann
            return (double)img[off<0?0:whds - 1];
          default : // Dirichlet
            return 0;
          }
        return 0;
      }

      static double mp_ijxyzc3(_cimg_math_parser& mp) {
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(8),
          boundary_conditions = (unsigned int)_mp_arg(9);
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4),
          y = is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5),
          z = is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6);
        const int c = (int)(is_relative?(mp.mem[_cimg_mp_slot_c] + _mp_arg(7)):_mp_arg(7));
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mc = cimg::mod(c,s2);
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              mz = cimg::mod((float)z,(float)d2);
            return (double)img._cubic_atXYZ(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                            mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._cubic_atXYZ_p((float)x,(float)y,(float)z,cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._cubic_atXYZ((float)x,(float)y,(float)z,c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.cubic_atXYZ((float)x,(float)y,(float)z,c,(T)0);
          }
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mc = cimg::mod(c,s2);
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              mz = cimg::mod((float)z,(float)d2);
            return (double)img._linear_atXYZ(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                             mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._linear_atXYZ_p((float)x,(float)y,(float)z,cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._linear_atXYZ((float)x,(float)y,(float)z,c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.linear_atXYZ((float)x,(float)y,(float)z,c,(T)0);
          }
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mc = cimg::mod(c,s2),
              mx = cimg::mod((int)x,w2),
              my = cimg::mod((int)y,h2),
              mz = cimg::mod((int)z,d2);
            return (double)img(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                               mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img((int)cimg::mod(x,(double)img._width),(int)cimg::mod(y,(double)img._height),
                               (int)cimg::mod(z,(double)img._depth),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._atXYZC((int)x,(int)y,(int)z,c);
          default : // Dirichlet
            return (double)img.atXYZC((int)x,(int)y,(int)z,c,(T)0);
          }
        }
      }

      static double mp_ijxyzc2(_cimg_math_parser& mp) {
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(8),
          boundary_conditions = (unsigned int)_mp_arg(9);
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4),
          y = is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5);
        const int
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6)),
          c = (int)(is_relative?(mp.mem[_cimg_mp_slot_c] + _mp_arg(7)):_mp_arg(7));
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2);
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2);
            return (double)img._cubic_atXY(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                           mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._cubic_atXY_p((float)x,(float)y,cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._cubic_atXY((float)x,(float)y,
                                           z<0?0:z>=img.depth()?img.depth() - 1:z,
                                           c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (z<0 || z>=img.depth() || c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.cubic_atXY((float)x,(float)y,z,c,(T)0);
          }
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2);
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2);
            return (double)img._linear_atXY(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                            mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._linear_atXY_p((float)x,(float)y,cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._linear_atXY((float)x,(float)y,
                                            z<0?0:z>=img.depth()?img.depth() - 1:z,
                                            c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (z<0 || z>=img.depth() || c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.linear_atXY((float)x,(float)y,z,c,(T)0);
          }
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2),
              mx = cimg::mod((int)x,w2),
              my = cimg::mod((int)y,h2);
            return (double)img(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                               mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img((int)cimg::mod(x,(double)img._width),(int)cimg::mod(y,(double)img._height),
                               cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._atXYZC((int)x,(int)y,z,c);
          default : // Dirichlet
            return (double)img.atXYZC((int)x,(int)y,z,c,(T)0);
          }
        }
      }

      static double mp_ijxyzc1(_cimg_math_parser& mp) {
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(8),
          boundary_conditions = (unsigned int)_mp_arg(9);
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4);
        const int
          y = (int)(is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5)),
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6)),
          c = (int)(is_relative?(mp.mem[_cimg_mp_slot_c] + _mp_arg(7)):_mp_arg(7));
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2);
            const float mx = cimg::mod((float)x,(float)w2);
            return (double)img._cubic_atX(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                          mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._cubic_atX_p((float)x,cimg::mod(y,img.height()),
                                            cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._cubic_atX((float)x,
                                          y<0?0:y>=img.height()?img.height() - 1:y,
                                          z<0?0:z>=img.depth()?img.depth() - 1:z,
                                          c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (y<0 || y>=img.height() || z<0 || z>=img.depth() || c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.cubic_atX((float)x,y,z,c,(T)0);
          }
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2);
            const float mx = cimg::mod((float)x,(float)w2);
            return (double)img._linear_atX(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                                           mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img._linear_atX_p((float)x,cimg::mod(y,img.height()),
                                             cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._linear_atX((float)x,
                                           y<0?0:y>=img.height()?img.height() - 1:y,
                                           z<0?0:z>=img.depth()?img.depth() - 1:z,
                                           c<0?0:c>=img.spectrum()?img.spectrum() - 1:c);
          default : // Dirichlet
            if (y<0 || y>=img.height() || z<0 || z>=img.depth() || c<0 || c>=img.spectrum()) return (T)0;
            return (double)img.linear_atX((float)x,y,z,c,(T)0);
          }
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(), s2 = 2*img.spectrum(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              mc = cimg::mod(c,s2),
              mx = cimg::mod((int)x,w2);
            return (double)img(mx<img.width()?mx:w2 - mx - 1,my<img.height()?my:h2 - my - 1,
                               mz<img.depth()?mz:d2 - mz - 1,mc<img.spectrum()?mc:s2 - mc - 1);
          }
          case 2 : // Periodic
            return (double)img((int)cimg::mod(x,(double)img._width),cimg::mod(y,img.height()),
                               cimg::mod(z,img.depth()),cimg::mod(c,img.spectrum()));
          case 1 : // Neumann
            return (double)img._atXYZC((int)x,y,z,c);
          default : // Dirichlet
            return (double)img.atXYZC((int)x,y,z,c,(T)0);
          }
        }
      }

      static double mp_image_crop(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const int x = (int)_mp_arg(3), y = (int)_mp_arg(4), z = (int)_mp_arg(5), c = (int)_mp_arg(6);
        const unsigned int
          dx = (unsigned int)mp.opcode[7],
          dy = (unsigned int)mp.opcode[8],
          dz = (unsigned int)mp.opcode[9],
          dc = (unsigned int)mp.opcode[10];
        const unsigned int boundary_conditions = (unsigned int)_mp_arg(11);
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        if (!img) std::memset(ptrd,0,dx*dy*dz*dc*sizeof(double));
        else CImg<doubleT>(ptrd,dx,dy,dz,dc,true) = img.get_crop(x,y,z,c,
                                                                 x + dx - 1,y + dy - 1,
                                                                 z + dz - 1,c + dc - 1,
                                                                 boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_image_depth(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.depth();
      }

      static double mp_image_display(_cimg_math_parser& mp) {
        mp_check_list(mp,"display");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        cimg::mutex(6);
        CImg<T> &img = mp.imglist[ind];
        CImg<charT> title(256);
        std::fputc('\n',cimg::output());
        cimg_snprintf(title,title._width,"[ Image #%u ]",ind);
        img.display(title);
        cimg::mutex(6,0);
        return cimg::type<double>::nan();
      }

      static double mp_image_draw(_cimg_math_parser& mp) {
        const int x = (int)_mp_arg(4), y = (int)_mp_arg(5), z = (int)_mp_arg(6), c = (int)_mp_arg(7);
        unsigned int ind = (unsigned int)mp.opcode[3];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(3),mp.imglist.width());
        }
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        unsigned int
          dx = (unsigned int)mp.opcode[8],
          dy = (unsigned int)mp.opcode[9],
          dz = (unsigned int)mp.opcode[10],
          dc = (unsigned int)mp.opcode[11];
        dx = dx==~0U?img._width:(unsigned int)_mp_arg(8);
        dy = dy==~0U?img._height:(unsigned int)_mp_arg(9);
        dz = dz==~0U?img._depth:(unsigned int)_mp_arg(10);
        dc = dc==~0U?img._spectrum:(unsigned int)_mp_arg(11);

        const ulongT sizS = mp.opcode[2];
        if (sizS<(ulongT)dx*dy*dz*dc)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                      "Sprite vector (%lu values) and its specified geometry (%u,%u,%u,%u) "
                                      "(%lu values) do not match.",
                                      mp.imgin.pixel_type(),sizS,dx,dy,dz,dc,(ulongT)dx*dy*dz*dc);
        const CImg<doubleT> S(&_mp_arg(1) + 1,dx,dy,dz,dc,true);
        const float opacity = (float)_mp_arg(12);

        if (img._data) {
          if (mp.opcode[13]!=~0U) { // Opacity mask specified
            const ulongT sizM = mp.opcode[14];
            if (sizM<(ulongT)dx*dy*dz)
              throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                          "Mask vector (%lu values) and specified sprite geometry (%u,%u,%u,%u) "
                                          "(%lu values) do not match.",
                                          mp.imgin.pixel_type(),sizS,dx,dy,dz,dc,(ulongT)dx*dy*dz*dc);
            const CImg<doubleT> M(&_mp_arg(13) + 1,dx,dy,dz,(unsigned int)(sizM/(dx*dy*dz)),true);
            img.draw_image(x,y,z,c,S,M,opacity,(float)_mp_arg(15));
          } else img.draw_image(x,y,z,c,S,opacity);
        }
        return cimg::type<double>::nan();
      }

      static double mp_image_find(_cimg_math_parser& mp) {
        const unsigned int
          indi = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        const CImg<T> &img = mp.imglist[indi];
        const int _step = (int)_mp_arg(5), step = _step?_step:-1;
        const ulongT siz = (ulongT)img.size();
        longT ind = (longT)(mp.opcode[4]!=_cimg_mp_slot_nan?_mp_arg(4):step>0?0:siz - 1);
        if (ind<0 || ind>=(longT)siz) return -1.;
        const T
          *const ptrb = img.data(),
          *const ptre = img.end(),
          *ptr = ptrb + ind;
        const double val = _mp_arg(3);

        // Forward search.
        if (step>0) {
          if (cimg::type<double>::is_nan(val))
            while (ptr<ptre && !cimg::type<double>::is_nan(*ptr)) ptr+=step;
          else
            while (ptr<ptre && (double)*ptr!=val) ptr+=step;
          return ptr>=ptre?-1.:(double)(ptr - ptrb);
        }

        // Backward search.
        if (cimg::type<double>::is_nan(val))
          while (ptr>=ptrb && !cimg::type<double>::is_nan(*ptr)) ptr+=step;
        else
          while (ptr>=ptrb && (double)*ptr!=val) ptr+=step;
        return ptr<ptrb?-1.:(double)(ptr - ptrb);
      }

      static double mp_image_find_seq(_cimg_math_parser& mp) {
        const unsigned int
          indi = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        const CImg<T> &img = mp.imglist[indi];
        const int _step = (int)_mp_arg(6), step = _step?_step:-1;
        const ulongT
          siz1 = (ulongT)img.size(),
          siz2 = (ulongT)mp.opcode[4];
        longT ind = (longT)(mp.opcode[5]!=_cimg_mp_slot_nan?_mp_arg(5):step>0?0:siz1 - 1);
        if (ind<0 || ind>=(longT)siz1) return -1.;
        const T
          *const ptr1b = img.data(),
          *const ptr1e = ptr1b + siz1,
          *ptr1 = ptr1b + ind,
          *p1 = 0;
        const double
          *const ptr2b = &_mp_arg(3) + 1,
          *const ptr2e = ptr2b + siz2,
          *p2 = 0;

        // Forward search.
        if (step>0) {
          do {
            if (cimg::type<double>::is_nan(*ptr2b))
              while (ptr1<ptr1e && !cimg::type<double>::is_nan(*ptr1)) ptr1+=step;
            else
              while (ptr1<ptr1e && *ptr1!=*ptr2b) ptr1+=step;
            if (ptr1>=ptr1e) return -1.;
            p1 = ptr1 + 1;
            p2 = ptr2b + 1;
            while (p1<ptr1e && p2<ptr2e &&
                   ((cimg::type<double>::is_nan(*p1) && cimg::type<double>::is_nan(*p2)) || *p1==*p2)) { ++p1; ++p2; }
          } while (p2<ptr2e && (ptr1+=step)<ptr1e);
          return p2<ptr2e?-1.:(double)(ptr1 - ptr1b);
        }

        // Backward search.
        do {
          if (cimg::type<double>::is_nan(*ptr2b))
            while (ptr1>=ptr1b && !cimg::type<double>::is_nan(*ptr1)) ptr1+=step;
          else
            while (ptr1>=ptr1b && *ptr1!=*ptr2b) ptr1+=step;
          if (ptr1<ptr1b) return -1.;
          p1 = ptr1 + 1;
          p2 = ptr2b + 1;
          while (p1<ptr1e && p2<ptr2e &&
                 ((cimg::type<double>::is_nan(*p1) && cimg::type<double>::is_nan(*p2)) || *p1==*p2)) { ++p1; ++p2; }
        } while (p2<ptr2e && (ptr1+=step)>=ptr1b);
        return p2<ptr2e?-1.:(double)(ptr1 - ptr1b);
      }

      static double mp_image_height(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.height();
      }

      static double mp_image_is_shared(_cimg_math_parser& mp) {
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        return (double)mp.imglist[ind]._is_shared;
      }

      static double mp_image_print(_cimg_math_parser& mp) {
        mp_check_list(mp,"print");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        cimg::mutex(6);
        CImg<T> &img = mp.imglist[ind];
        CImg<charT> title(256);
        std::fputc('\n',cimg::output());
        cimg_snprintf(title,title._width,"[ Image #%u ]",ind);
        img.print(title);
        cimg::mutex(6,0);
        return cimg::type<double>::nan();
      }

      static double mp_image_resize(_cimg_math_parser& mp) {
        mp_check_list(mp,"resize");
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        cimg::mutex(6);
        CImg<T> &img = mp.imglist[ind];
        const double
          _w = mp.opcode[3]==~0U?-100:_mp_arg(3),
          _h = mp.opcode[4]==~0U?-100:_mp_arg(4),
          _d = mp.opcode[5]==~0U?-100:_mp_arg(5),
          _s = mp.opcode[6]==~0U?-100:_mp_arg(6);
        const unsigned int
          w = (unsigned int)(_w>=0?_w:-_w*img.width()/100),
          h = (unsigned int)(_h>=0?_h:-_h*img.height()/100),
          d = (unsigned int)(_d>=0?_d:-_d*img.depth()/100),
          s = (unsigned int)(_s>=0?_s:-_s*img.spectrum()/100),
          interp = (int)_mp_arg(7);
        if (mp.is_fill && img._data==mp.imgout._data) {
          cimg::mutex(6,0);
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'resize()': "
                                      "Cannot both fill/eval and resize image (%u,%u,%u,%u) "
                                      "to new dimensions (%u,%u,%u,%u).",
                                      img.pixel_type(),img._width,img._height,img._depth,img._spectrum,w,h,d,s);
        }
        const unsigned int
          boundary = (int)_mp_arg(8);
        const float
          cx = (float)_mp_arg(9),
          cy = (float)_mp_arg(10),
          cz = (float)_mp_arg(11),
          cc = (float)_mp_arg(12);
        img.resize(w,h,d,s,interp,boundary,cx,cy,cz,cc);
        cimg::mutex(6,0);
        return cimg::type<double>::nan();
      }

      static double mp_image_shift(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[3],
          h = (unsigned int)mp.opcode[4],
          d = (unsigned int)mp.opcode[5],
          s = (unsigned int)mp.opcode[6];
        const double dx = _mp_arg(7), dy = _mp_arg(8), dz = _mp_arg(9), dc = _mp_arg(10);
        const unsigned int boundary_conditions = (unsigned int)cimg::cut(_mp_arg(11),0.,3.);
        CImg<doubleT>(ptrd,w,h,d,s,true) =
          CImg<doubleT>(ptrs,w,h,d,s,true).get_shift(dx,dy,dz,dc,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_image_shift_ip(_cimg_math_parser& mp) {
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[3],
          h = (unsigned int)mp.opcode[4],
          d = (unsigned int)mp.opcode[5],
          s = (unsigned int)mp.opcode[6];
        const double dx = _mp_arg(7), dy = _mp_arg(8), dz = _mp_arg(9), dc = _mp_arg(10);
        const unsigned int boundary_conditions = (unsigned int)cimg::cut(_mp_arg(11),0.,3.);
        CImg<doubleT>(ptrs,w,h,d,s,true).shift(dx,dy,dz,dc,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_image_spectrum(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.spectrum();
      }

      static double mp_image_stats(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind==~0U)
          CImg<doubleT>(ptrd,15,1,1,1,true) = mp.imgout.get_stats();
        else {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
          CImg<doubleT>(ptrd,15,1,1,1,true) = mp.imglist[ind].get_stats();
        }
        return cimg::type<double>::nan();
      }

      static double mp_image_stats_cm(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0, z = 0, c = 0;
        img.contains(img.min(),x,y,z,c);
        return (double)c;
      }

      static double mp_image_stats_cM(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0, z = 0, c = 0;
        img.contains(img.max(),x,y,z,c);
        return (double)c;
      }

      static double mp_image_stats_ia(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.mean();
      }

      static double mp_image_stats_ic(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.median();
      }

      static double mp_image_stats_ic_static(_cimg_math_parser& mp) {
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        if (!mp.list_median) mp.list_median.assign(mp.imglist._width);
        if (!mp.list_median[ind]) CImg<doubleT>::vector(mp.imglist[ind].median()).move_to(mp.list_median[ind]);
        return *mp.list_median[ind];
      }

      static double mp_image_stats_id(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)std::sqrt(img.variance());
      }

      static double mp_image_stats_id_static(_cimg_math_parser& mp) {
        const unsigned int ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        bool get_stats = false;
        cimg::mutex(13);
        if (!mp.list_stats || mp.list_stats.size()!=mp.imglist._width) mp.list_stats.assign(mp.imglist._width);
        if (!mp.list_stats[ind]) get_stats = true;
        cimg::mutex(13,0);
        if (get_stats) {
          CImg<Tdouble> st = mp.imglist[ind].get_stats();
          cimg::mutex(13);
          st.move_to(mp.list_stats[ind]);
          cimg::mutex(13,0);
        }
        return mp.list_stats[ind].is_empty()?cimg::type<double>::nan():std::sqrt(mp.list_stats(ind,3));
      }

      static double mp_image_stats_im(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.min();
      }

      static double mp_image_stats_iM(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.max();
      }

      static double mp_image_stats_in(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.magnitude(2);
      }

      static double mp_image_stats_ip(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.product();
      }

      static double mp_image_stats_is(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.sum();
      }

      static double mp_image_stats_iv(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.variance();
      }

      static double mp_image_stats_static(_cimg_math_parser& mp) {
        const unsigned int
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width()),
          k = (unsigned int)mp.opcode[3];
        bool get_stats = false;
        cimg::mutex(13);
        if (!mp.list_stats || mp.list_stats.size()!=mp.imglist._width) mp.list_stats.assign(mp.imglist._width);
        if (!mp.list_stats[ind]) get_stats = true;
        cimg::mutex(13,0);
        if (get_stats) {
          CImg<Tdouble> st = mp.imglist[ind].get_stats();
          cimg::mutex(13);
          st.move_to(mp.list_stats[ind]);
          cimg::mutex(13,0);
        }
        return mp.list_stats[ind].is_empty()?cimg::type<double>::nan():mp.list_stats(ind,k);
      }

      static double mp_image_stats_xm(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0;
        img.contains(img.min(),x);
        return (double)x;
      }

      static double mp_image_stats_xM(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0;
        img.contains(img.max(),x);
        return (double)x;
      }

      static double mp_image_stats_ym(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0;
        img.contains(img.min(),x,y);
        return (double)y;
      }

      static double mp_image_stats_yM(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0;
        img.contains(img.max(),x,y);
        return (double)y;
      }

      static double mp_image_stats_zm(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0, z = 0;
        img.contains(img.min(),x,y,z);
        return (double)z;
      }

      static double mp_image_stats_zM(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        int x = 0, y = 0, z = 0;
        img.contains(img.max(),x,y,z);
        return (double)z;
      }

      static double mp_image_swap(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (!mp.imglist.width()) return cimg::type<double>::nan();
        ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        CImg<T> &img = mp.imglist[ind];
        const longT
          pos0 = (longT)_mp_arg(3),
          pos1 = (longT)_mp_arg(4);
        const bool is_vector = (bool)_mp_arg(5);
        if (is_vector) {
          const longT whd = (longT)img.size()/img.spectrum();
          T *ptr0 = &img[pos0], *ptr1 = &img[pos1];
          if (pos0>=0 && pos0<=whd && pos1>=0 && pos1<=whd)
            for (unsigned int c = 0; c<img._spectrum; ++c) {
              cimg::swap(*ptr0,*ptr1);
              ptr0+=whd;
              ptr1+=whd;
            } else throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'swap()': "
                                               "Out-of-bounds offsets %ld and %ld (min offset: 0, max offset: %ld).",
                                               mp.imgin.pixel_type(),pos0,pos1,whd);
        } else {
          const longT whds = (longT)img.size();
          if (pos0>=0 && pos0<=whds && pos1>=0 && pos1<=whds)
            cimg::swap(img[pos0],img[pos1]);
          else throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'swap()': "
                                           "Out-of-bounds offsets %ld and %ld (min offset: 0, max offset: %ld).",
                                           mp.imgin.pixel_type(),pos0,pos1,whds);
        }
        return cimg::type<double>::nan();
      }

      static double mp_image_width(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.width();
      }

      static double mp_image_wh(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.width()*img.height();
      }

      static double mp_image_whd(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.width()*img.height()*img.depth();
      }

      static double mp_image_whds(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        return (double)img.width()*img.height()*img.depth()*img.spectrum();
      }

      static double mp_increment(_cimg_math_parser& mp) {
        return _mp_arg(2) + 1;
      }

      static double mp_index(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          sizA = (unsigned int)mp.opcode[3],
          sizP = (unsigned int)mp.opcode[5],
          dim_colors = (unsigned int)mp.opcode[6],
          nb_colors = sizP/dim_colors,
          wA = sizA/dim_colors;
        const double dithering = _mp_arg(7);
        const bool map_colors = (bool)mp.opcode[8];
        const double
          *const ptrs = &_mp_arg(2) + 1,
          *const ptrp = &_mp_arg(4) + 1;
        CImg<doubleT> colormap(ptrp,nb_colors,1,1,dim_colors,true);
        CImg<doubleT>(ptrd,wA,1,1,map_colors?dim_colors:1,true) = CImg<doubleT>(ptrs,wA,1,1,dim_colors,true).
          get_index(colormap,dithering,map_colors);
        return cimg::type<double>::nan();
      }

      static double mp_indexof(_cimg_math_parser& mp) {
        const unsigned int
          siz = (unsigned int)mp.opcode[2],
          siz_ref = (unsigned int)mp.opcode[4];
        if (!siz_ref) { // Reference value is a scalar
          const double ref = _mp_arg(3);
          for (unsigned int k = 5; k<siz; k+=2) {
            const unsigned int siz_elt = (unsigned int)mp.opcode[k + 1];
            if (!siz_elt) {
              const double elt = _mp_arg(k);
              if (elt==ref) return (double)((k - 5)/2);
            }
          }
        } else { // Reference value is a vector
          const double *const ptr_r = &_mp_arg(3) + 1;
          for (unsigned int k = 5; k<siz; k+=2) {
            const unsigned int siz_elt = (unsigned int)mp.opcode[k + 1];
            if (siz_elt==siz_ref) {
              const double *const ptr_e = &_mp_arg(k) + 1;
              bool is_same = true;
              for (unsigned int l = 0; l<siz_ref; ++l)
                if (ptr_e[l]!=ptr_r[l]) { is_same = false; break; }
              if (is_same) return (double)((k - 5)/2);
            }
          }
        }
        return -1;
      }

      static double mp_inrange(_cimg_math_parser& mp) {
        const unsigned int sizd = (unsigned int)mp.opcode[2];
        const bool
          include_m = (bool)_mp_arg(9),
          include_M = (bool)_mp_arg(10);
        if (!sizd) { // Scalar result
          const double val = _mp_arg(3);
          const double m = _mp_arg(5), M = _mp_arg(7);
          if (M>=m) return (double)((include_m?(val>=m):(val>m)) && (include_M?(val<=M):(val<M)));
          else return (double)((include_M?(val>=M):(val>M)) && (include_m?(val<=m):(val<m)));
        }

        // Vector result.
        const unsigned int
          siz1 = (unsigned int)mp.opcode[4],
          siz2 = (unsigned int)mp.opcode[6],
          siz3 = (unsigned int)mp.opcode[8],
          off1 = siz1?1:0,
          off2 = siz2?1:0,
          off3 = siz3?1:0;
        double *ptrd = &_mp_arg(1) + 1;
        const double
          *ptr1 = &_mp_arg(3) + off1,
          *ptr2 = &_mp_arg(5) + off2,
          *ptr3 = &_mp_arg(7) + off3;
        for (unsigned int k = 0; k<sizd; ++k) {
          const double val = *ptr1;
          const double m = *ptr2, M = *ptr3;
          if (M>=m)
            ptrd[k] = (double)((include_m?(val>=m):(val>m)) && (include_M?(val<=M):(val<M)));
          else
            ptrd[k] = (double)((include_M?(val>=M):(val>M)) && (include_m?(val<=m):(val<m)));
          ptr1+=off1;
          ptr2+=off2;
          ptr3+=off3;
        }
        return cimg::type<double>::nan();
      }

      static double mp_isdir(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double *const ptrs = &_mp_arg(2) + (siz?1:0);
        if (!siz) { char str[2] = {}; *str = *ptrs; return (double)cimg::is_directory(str); }
        CImg<charT> ss(siz + 1);
        cimg_forX(ss,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        return (double)cimg::is_directory(ss);
      }

      static double mp_isfile(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double *const ptrs = &_mp_arg(2) + (siz?1:0);
        if (!siz) { char str[2] = {}; *str = *ptrs; return (double)cimg::is_file(str); }
        CImg<charT> ss(siz + 1);
        cimg_forX(ss,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        return (double)cimg::is_file(ss);
      }

      static double mp_isin(_cimg_math_parser& mp) {
        const unsigned int
          i_end = (unsigned int)mp.opcode[2],
          siz_ref = (unsigned int)mp.opcode[4];
        bool res = false;
        if (siz_ref) { // Reference value is a vector
          const CImg<doubleT> ref(&_mp_arg(3) + 1,siz_ref,1,1,1,true);
          for (unsigned int i = 5; i<i_end; i+=2) {
            const unsigned int siz = (unsigned int)mp.opcode[i + 1];
            if (siz==siz_ref && CImg<doubleT>(&_mp_arg(i) + 1,siz,1,1,1,true)==ref) { res = true; break; }
          }
        } else { // Reference value is a scalar
          const double ref = _mp_arg(3);
          for (unsigned i = 5; i<i_end; i+=2) {
            const unsigned int siz = (unsigned int)mp.opcode[i + 1];
            if (!siz && _mp_arg(i)==ref) { res = true; break; }
          }
        }
        return res?1.:0.;
      }

      static double mp_isint(_cimg_math_parser& mp) {
        const double val = _mp_arg(2), imin = mp.opcode[3]==~0U?0:_mp_arg(3), imax = mp.opcode[4]==~0U?0:_mp_arg(4);
        double intpart;
        const bool is_int = std::modf(val,&intpart)==0;
        if (mp.opcode[3]==~0U) return is_int;
        if (mp.opcode[4]==~0U) return is_int && val>=imin;
        return is_int && val>=imin && val<=imax;
      }

      static double mp_vector_isint(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const double
          *const ptrs = &_mp_arg(3) + 1,
          imin = mp.opcode[4]==~0U?0:_mp_arg(4),
          imax = mp.opcode[5]==~0U?0:_mp_arg(5);
        double intpart;
        for (unsigned int k = 0; k<siz; ++k) {
          double val = ptrs[k];
          const bool is_int = std::modf(val,&intpart)==0;
          if (mp.opcode[4]==~0U) val = (double)is_int;
          else if (mp.opcode[5]==~0U) val = (double)(is_int && val>=imin);
          else val = (double)(is_int && val>=imin && val<=imax);
          ptrd[k] = val;
        }
        return cimg::type<double>::nan();
      }

      static double mp_isvarname(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double *ptrs = &_mp_arg(2) + (siz?1:0);
        if (!siz) {
          const char c = (char)*ptrs;
          return (c>='a' && c<='z') || (c>='A' && c<='Z') || c=='_';
        }
        if (*ptrs>='0' && *ptrs<='9') return 0;
        for (unsigned int k = 0; k<siz; ++k) if (!cimg::is_varchar((char)ptrs[k])) return 0;
        return 1;
      }

      static double mp_kth(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        CImg<doubleT> values;
        if (i_end==5) values.assign(&_mp_arg(3),(unsigned int)mp.opcode[4],1,1,1,true); // Only a single argument
        else {
          unsigned int siz = 0;
          for (unsigned int i = 4; i<i_end; i+=2) siz+=(unsigned int)mp.opcode[i];
          values.assign(siz);
          double *ptr = values;
          for (unsigned int i = 3; i<i_end; i+=2) {
            const unsigned int len = (unsigned int)mp.opcode[i + 1];
            if (len>1) std::memcpy(ptr,&_mp_arg(i),len*sizeof(double));
            else *ptr = _mp_arg(i);
            ptr+=len;
          }
        }
        longT ind = (longT)values[0];
        ++values._data; --values._width; // Skip first value
        if (ind<0) ind+=values.width() + 1;
        ind = cimg::cut(ind,(longT)1,(longT)values.width());
        const double &kth = values.kth_smallest((ulongT)(ind - 1));
        --values._data; ++values._width;
        return kth;
      }

      static double mp_lcm(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        CImg<cimg_int64> values;
        if (i_end==5) { // Only a single argument
          if ((unsigned)mp.opcode[4]==1) return _mp_arg(3); // Real value
          else values.assign(&_mp_arg(3),(unsigned int)mp.opcode[4]); // Vector value
        } else if (i_end==7 && (unsigned int)mp.opcode[4]==1 && (unsigned int)mp.opcode[6]==1) // Two real arguments
          return (double)cimg::lcm((cimg_int64)_mp_arg(3),(cimg_int64)_mp_arg(5));
        else {
          unsigned int siz = 0;
          for (unsigned int i = 4; i<i_end; i+=2) siz+=(unsigned int)mp.opcode[i];
          values.assign(siz);
          cimg_int64 *ptr = values;
          for (unsigned int i = 3; i<i_end; i+=2) {
            const unsigned int len = (unsigned int)mp.opcode[i + 1];
            double *ptrs = &_mp_arg(i);
            if (len>1) for (unsigned int k = 0; k<len; ++k) *(ptr++) = (cimg_int64)ptrs[k];
            else *(ptr++) = (cimg_int64)_mp_arg(i);
          }
        }
        return values.lcm();
      }

      static double mp_lcm2(_cimg_math_parser& mp) {
        return cimg::lcm((cimg_int64)_mp_arg(2),(cimg_int64)_mp_arg(3));
      }

      static double mp_lerp(_cimg_math_parser& mp) {
        const double
          val0 = _mp_arg(2),
          val1 = _mp_arg(3),
          t = _mp_arg(4);
        return val0*(1 - t) + val1*t;
      }

      static double mp_logical_and(_cimg_math_parser& mp) {
        const bool val_left = (bool)_mp_arg(2);
        const CImg<ulongT> *const p_end = ++mp.p_code + mp.opcode[4];
        if (!val_left) { mp.p_code = p_end - 1; return 0; }
        const ulongT mem_right = mp.opcode[3];
        mp.eval(mp.p_code,p_end);
        --mp.p_code;
        return (double)(bool)mp.mem[mem_right];
      }

      static double mp_logical_or(_cimg_math_parser& mp) {
        const bool val_left = (bool)_mp_arg(2);
        const CImg<ulongT> *const p_end = ++mp.p_code + mp.opcode[4];
        if (val_left) { mp.p_code = p_end - 1; return 1; }
        const ulongT mem_right = mp.opcode[3];
        mp.eval(mp.p_code,p_end);
        --mp.p_code;
        return (double)(bool)mp.mem[mem_right];
      }

      static double mp_map(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1);
        const double *ptrX = &_mp_arg(2);
        unsigned int sizX = (unsigned int)mp.opcode[3];
        const double *const ptrP = &_mp_arg(4) + 1;
        const unsigned int
          sizP = (unsigned int)mp.opcode[5],
          nb_channelsX = (unsigned int)mp.opcode[6],
          nb_channelsP = (unsigned int)mp.opcode[7],
          boundary_conditions = (unsigned int)_mp_arg(8);
        const bool
          is_scalar_input = !sizX,
          is_scalar_output = is_scalar_input && nb_channelsP==1;
        if (!is_scalar_output) ++ptrd;
        if (is_scalar_input) ++sizX; else ++ptrX;
        CImg<doubleT>(ptrd,sizX/nb_channelsX,1,1,nb_channelsX*nb_channelsP,true) =
          CImg<doubleT>(ptrX,sizX/nb_channelsX,1,1,nb_channelsX,true).
          get_map(CImg<doubleT>(ptrP,sizP/nb_channelsP,1,1,nb_channelsP,true),boundary_conditions);
        return is_scalar_output?ptrd[0]:cimg::type<double>::nan();
      }

      static double mp_matrix_eigen(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptr1 = &_mp_arg(2) + 1;
        const unsigned int k = (unsigned int)mp.opcode[3];
        CImg<doubleT> val, vec;
        CImg<doubleT>(ptr1,k,k,1,1,true).symmetric_eigen(val,vec);
        CImg<doubleT>(ptrd,1,k,1,1,true) = val;
        CImg<doubleT>(ptrd + k,k,k,1,1,true) = vec.get_transpose();
        return cimg::type<double>::nan();
      }

      static double mp_matrix_invert(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptr1 = &_mp_arg(2) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[3],
          h = (unsigned int)mp.opcode[4];
        CImg<doubleT>(ptrd,h,w,1,1,true) = CImg<doubleT>(ptr1,w,h,1,1,true).get_invert();
        return cimg::type<double>::nan();
      }

      static double mp_matrix_mul(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double
          *ptr1 = &_mp_arg(2) + 1,
          *ptr2 = &_mp_arg(3) + 1;
        const unsigned int
          k = (unsigned int)mp.opcode[4],
          l = (unsigned int)mp.opcode[5],
          m = (unsigned int)mp.opcode[6];
        CImg<doubleT>(ptrd,m,k,1,1,true) = CImg<doubleT>(ptr1,l,k,1,1,true)*CImg<doubleT>(ptr2,m,l,1,1,true);
        return cimg::type<double>::nan();
      }

      static double mp_matrix_qr(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int
          n = (unsigned int)mp.opcode[3],
          m = (unsigned int)mp.opcode[4],
          mn = std::min(m,n);
        const bool is_reduced_form = (bool)mp.opcode[5];
        CImg<doubleT> Q, R;
        CImg<doubleT>(ptrs,n,m,1,1,true).QR(Q,R,is_reduced_form);
        if (is_reduced_form) {
          CImg<doubleT>(ptrd,mn,m,1,1,true) = Q;
          CImg<doubleT>(ptrd + mn*m,n,mn,1,1,true) = R;
        } else {
          CImg<doubleT>(ptrd,m,m,1,1,true) = Q;
          CImg<doubleT>(ptrd + m*m,n,m,1,1,true) = R;
        }
        return cimg::type<double>::nan();
      }

      static double mp_matrix_svd(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int
          k = (unsigned int)mp.opcode[3],
          l = (unsigned int)mp.opcode[4];
        CImg<doubleT> U, S, V;
        CImg<doubleT>(ptrs,k,l,1,1,true).SVD(U,S,V);
        CImg<doubleT>(ptrd,k,l,1,1,true) = U;
        CImg<doubleT>(ptrd + k*l,1,k,1,1,true) = S;
        CImg<doubleT>(ptrd + k*l + k,k,k,1,1,true) = V;
        return cimg::type<double>::nan();
      }

      static double mp_max(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, valmax = -cimg::type<double>::inf();
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) { val = *(ptr++); if (val>valmax) valmax = val; }
          } else { val = _mp_arg(i); if (val>valmax) valmax = val; }
        }
        return valmax;
      }

      static double mp_max2(_cimg_math_parser& mp) {
        return std::max(_mp_arg(2),_mp_arg(3));
      }

      static double _mp_maxabs(_cimg_math_parser& mp, const bool compute_abs) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, abs_val, valmaxabs = 0, abs_valmaxabs = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) {
              val = *(ptr++);
              abs_val = cimg::abs(val);
              if (abs_val>abs_valmaxabs) { valmaxabs = val; abs_valmaxabs = abs_val; }
            }
          } else {
            val = _mp_arg(i);
            abs_val = cimg::abs(val);
            if (abs_val>abs_valmaxabs) { valmaxabs = val; abs_valmaxabs = abs_val; }
          }
        }
        return compute_abs?std::abs(valmaxabs):valmaxabs;
      }

      static double mp_maxabs(_cimg_math_parser& mp) {
        return _mp_maxabs(mp,false);
      }

      static double mp_maxabs2(_cimg_math_parser& mp) {
        return cimg::maxabs(_mp_arg(2),_mp_arg(3));
      }

      static double mp_med(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        CImg<doubleT> values;
        if (i_end==5) { // Only a single argument
          if ((unsigned)mp.opcode[4]==1) return _mp_arg(3); // Real value
          else values.assign(&_mp_arg(3),(unsigned int)mp.opcode[4],1,1,1,true); // Vector value
        } else {
          unsigned int siz = 0;
          for (unsigned int i = 4; i<i_end; i+=2) siz+=(unsigned int)mp.opcode[i];
          values.assign(siz);
          double *ptr = values;
          for (unsigned int i = 3; i<i_end; i+=2) {
            const unsigned int len = (unsigned int)mp.opcode[i + 1];
            if (len>1) std::memcpy(ptr,&_mp_arg(i),len*sizeof(double));
            else *ptr = _mp_arg(i);
            ptr+=len;
          }
        }
        return values.median();
      }

      static double mp_med2(_cimg_math_parser& mp) {
        return (_mp_arg(2) + _mp_arg(3))/2;
      }

      static double* _mp_mem_copy_double(_cimg_math_parser& mp, const unsigned int ind, const ulongT *const p_ref,
                                         const longT siz, const long inc) {
        const longT
          off = *p_ref?p_ref[1] + (longT)mp.mem[(longT)p_ref[2]] + 1:ind,
          eoff = off + (siz - 1)*inc;
        if (off<0 || eoff>=mp.mem.width())
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'copy()': "
                                      "Out-of-bounds variable pointer "
                                      "(length: %ld, increment: %ld, offset start: %ld, "
                                      "offset end: %ld, offset max: %u).",
                                      mp.imgin.pixel_type(),siz,inc,off,eoff,mp.mem._width - 1);
        return &mp.mem[off];
      }

      static T* _mp_mem_copy_T(_cimg_math_parser& mp, const ulongT *const p_ref,
                               const longT siz, const long inc, const bool is_out) {
        const unsigned ind = (unsigned int)p_ref[1];
        const CImg<T> &img = is_out?
          (ind==~0U?mp.imgout:mp.imglist[cimg::mod((int)mp.mem[ind],mp.imglist.width())]):
          (ind==~0U?mp.imgin:mp.imglist[cimg::mod((int)mp.mem[ind],mp.imglist.width())]);
        const bool is_relative = (bool)p_ref[2];
        int ox, oy, oz, oc;
        longT off = 0;
        if (is_relative) {
          ox = (int)mp.mem[_cimg_mp_slot_x];
          oy = (int)mp.mem[_cimg_mp_slot_y];
          oz = (int)mp.mem[_cimg_mp_slot_z];
          oc = (int)mp.mem[_cimg_mp_slot_c];
          off = img.offset(ox,oy,oz,oc);
        }
        if ((*p_ref)%2) {
          const int
            x = (int)mp.mem[p_ref[3]],
            y = (int)mp.mem[p_ref[4]],
            z = (int)mp.mem[p_ref[5]],
            c = *p_ref==5?0:(int)mp.mem[p_ref[6]];
          off+=img.offset(x,y,z,c);
        } else off+=(longT)mp.mem[p_ref[3]];
        const longT eoff = off + (siz - 1)*inc;
        if (off<0 || eoff>=(longT)img.size())
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'copy()': "
                                      "Out-of-bounds image pointer "
                                      "(length: %ld, increment: %ld, offset start: %ld, "
                                      "offset end: %ld, offset max: %lu).",
                                      mp.imgin.pixel_type(),siz,inc,off,eoff,img.size() - 1);
        return (T*)&img[off];
      }

      static double mp_mem_copy(_cimg_math_parser& mp) {
        longT siz = (longT)_mp_arg(4);
        const longT inc_d = (longT)_mp_arg(5), inc_s = (longT)_mp_arg(6);
        const float
          _opacity = (float)_mp_arg(7),
          opacity = (float)cimg::abs(_opacity),
          omopacity = 1 - std::max(_opacity,0.f);
        if (siz>0) {
          const bool
            is_doubled = mp.opcode[8]<=1,
            is_doubles = mp.opcode[15]<=1;
          if (is_doubled && is_doubles) { // (double*) <- (double*)
            double *ptrd = _mp_mem_copy_double(mp,(unsigned int)mp.opcode[2],&mp.opcode[8],siz,inc_d);
            const double *ptrs = _mp_mem_copy_double(mp,(unsigned int)mp.opcode[3],&mp.opcode[15],siz,inc_s);
            if (inc_d==1 && inc_s==1 && _opacity>=1) {
              if (ptrs + siz - 1<ptrd || ptrs>ptrd + siz - 1) std::memcpy(ptrd,ptrs,siz*sizeof(double));
              else std::memmove(ptrd,ptrs,siz*sizeof(double));
            } else {
              if (ptrs + (siz - 1)*inc_s<ptrd || ptrs>ptrd + (siz - 1)*inc_d) {
                if (_opacity>=1) while (siz-->0) { *ptrd = *ptrs; ptrd+=inc_d; ptrs+=inc_s; }
                else while (siz-->0) { *ptrd = omopacity**ptrd + opacity**ptrs; ptrd+=inc_d; ptrs+=inc_s; }
              } else { // Overlapping buffers
                CImg<doubleT> buf((unsigned int)siz);
                cimg_for(buf,ptr,double) { *ptr = *ptrs; ptrs+=inc_s; }
                ptrs = buf;
                if (_opacity>=1) while (siz-->0) { *ptrd = *(ptrs++); ptrd+=inc_d; }
                else while (siz-->0) { *ptrd = omopacity**ptrd + opacity**(ptrs++); ptrd+=inc_d; }
              }
            }
          } else if (is_doubled && !is_doubles) { // (double*) <- (T*)
            double *ptrd = _mp_mem_copy_double(mp,(unsigned int)mp.opcode[2],&mp.opcode[8],siz,inc_d);
            const T *ptrs = _mp_mem_copy_T(mp,&mp.opcode[15],siz,inc_s,false);
            if (_opacity>=1) while (siz-->0) { *ptrd = *ptrs; ptrd+=inc_d; ptrs+=inc_s; }
            else while (siz-->0) { *ptrd = omopacity**ptrd + _opacity**ptrs; ptrd+=inc_d; ptrs+=inc_s; }
          } else if (!is_doubled && is_doubles) { // (T*) <- (double*)
            T *ptrd = _mp_mem_copy_T(mp,&mp.opcode[8],siz,inc_d,true);
            const double *ptrs = _mp_mem_copy_double(mp,(unsigned int)mp.opcode[3],&mp.opcode[15],siz,inc_s);
            if (_opacity>=1) while (siz-->0) { *ptrd = (T)*ptrs; ptrd+=inc_d; ptrs+=inc_s; }
            else while (siz-->0) { *ptrd = (T)(omopacity**ptrd + opacity**ptrs); ptrd+=inc_d; ptrs+=inc_s; }
          } else { // (T*) <- (T*)
            T *ptrd = _mp_mem_copy_T(mp,&mp.opcode[8],siz,inc_d,true);
            const T *ptrs = _mp_mem_copy_T(mp,&mp.opcode[15],siz,inc_s,false);
            if (inc_d==1 && inc_s==1 && _opacity>=1) {
              if (ptrs + siz - 1<ptrd || ptrs>ptrd + siz - 1) std::memcpy(ptrd,ptrs,siz*sizeof(T));
              else std::memmove(ptrd,ptrs,siz*sizeof(T));
            } else {
              if (ptrs + (siz - 1)*inc_s<ptrd || ptrs>ptrd + (siz - 1)*inc_d) {
                if (_opacity>=1) while (siz-->0) { *ptrd = *ptrs; ptrd+=inc_d; ptrs+=inc_s; }
                else while (siz-->0) { *ptrd = omopacity**ptrd + opacity**ptrs; ptrd+=inc_d; ptrs+=inc_s; }
              } else { // Overlapping buffers
                CImg<T> buf((unsigned int)siz);
                cimg_for(buf,ptr,T) { *ptr = *ptrs; ptrs+=inc_s; }
                ptrs = buf;
                if (_opacity>=1) while (siz-->0) { *ptrd = *(ptrs++); ptrd+=inc_d; }
                else while (siz-->0) { *ptrd = omopacity**ptrd + opacity**(ptrs++); ptrd+=inc_d; }
              }
            }
          }
        }
        return _mp_arg(1);
      }

      static double mp_mem_display(_cimg_math_parser& mp) {
        cimg::unused(mp);
        std::fputc('\n',cimg::output());
        CImg<charT> title(128);
        cimg_snprintf(title,title._width,"%s (%u)","[" cimg_appname "_math_parser] Memory snapshot",mp.mem._width);
        mp.mem.display(title);
        return cimg::type<double>::nan();
      }

      static double mp_min(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, valmin = cimg::type<double>::inf();
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) { val = *(ptr++); if (val<valmin) valmin = val; }
          } else { val = _mp_arg(i); if (val<valmin) valmin = val; }
        }
        return valmin;
      }

      static double mp_min2(_cimg_math_parser& mp) {
        return std::min(_mp_arg(2),_mp_arg(3));
      }

      static double _mp_minabs(_cimg_math_parser& mp, const bool compute_abs) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double val, abs_val, valminabs = cimg::type<double>::inf(), abs_valminabs = cimg::type<double>::inf();
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) {
              val = *(ptr++);
              abs_val = cimg::abs(val);
              if (abs_val<abs_valminabs) { valminabs = val; abs_valminabs = abs_val; }
            }
          } else {
            val = _mp_arg(i);
            abs_val = cimg::abs(val);
            if (abs_val<abs_valminabs) { valminabs = val; abs_valminabs = abs_val; }
          }
        }
        return compute_abs?std::abs(valminabs):valminabs;
      }

      static double mp_minabs(_cimg_math_parser& mp) {
        return _mp_minabs(mp,false);
      }

      static double mp_minabs2(_cimg_math_parser& mp) {
        return cimg::minabs(_mp_arg(2),_mp_arg(3));
      }

      static double mp_mirror(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double
          *const ptrs = &_mp_arg(2) + 1,
          *const ptrp = &_mp_arg(7) + 1;
        CImg<charT> str(std::max(1U,sizp) + 1);
        if (!sizp) str[0] = _mp_arg(7);
        else for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
        str.back() = 0;
        CImg<doubleT>(ptrd,wA,hA,dA,sA,true) = CImg<doubleT>(ptrs,wA,hA,dA,sA,true).
          get_mirror(str);
        return cimg::type<double>::nan();
      }

      static double mp_mirror_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double *const ptrp = &_mp_arg(7) + 1;
        CImg<charT> str(std::max(1U,sizp) + 1);
        if (!sizp) str[0] = _mp_arg(7);
        else for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
        str.back() = 0;
        CImg<doubleT>(ptrs,wA,hA,dA,sA,true).mirror(str);
        return cimg::type<double>::nan();
      }

      static double mp_mproj(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double
          *ptrS = &_mp_arg(2) + 1,
          *ptrD = &_mp_arg(5) + 1;
        const unsigned int
          wS = (unsigned int)mp.opcode[3],
          hS = (unsigned int)mp.opcode[4],
          wD = (unsigned int)mp.opcode[6];
        const int
          method = std::max(0,(int)_mp_arg(7)),
          max_iter = std::max(0,(int)_mp_arg(8));
        const double
          max_residual = std::max(0.,_mp_arg(9));

        CImg<doubleT>(ptrd,wS,wD,1,1,true) = CImg<doubleT>(ptrS,wS,hS,1,1,false).
          project_matrix(CImg<doubleT>(ptrD,wD,hS,1,1,true),method,max_iter,max_residual);
        return cimg::type<double>::nan();
      }

      static double mp_mse(_cimg_math_parser& mp) {
        const unsigned int
          _siz = (unsigned int)mp.opcode[4],
          siz = std::max(_siz,1U),
          off = _siz?1:0;
        return CImg<doubleT>(&_mp_arg(2) + off,1,siz,1,1,true).
          MSE(CImg<doubleT>(&_mp_arg(3) + off,1,siz,1,1,true));
      }

      static double mp_mul_div(_cimg_math_parser& mp) {
        return _mp_arg(2)*_mp_arg(3)/_mp_arg(4);
      }

      static double mp_mul_mul(_cimg_math_parser& mp) {
        return _mp_arg(2)*_mp_arg(3)*_mp_arg(4);
      }

      static double mp_mul_sub(_cimg_math_parser& mp) {
        return _mp_arg(2)*_mp_arg(3) - _mp_arg(4);
      }

#ifdef cimg_mp_func_name
      static double mp_name(_cimg_math_parser& mp) {
        double *const ptr = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind==~0U) std::memset(ptr,0,siz*sizeof(double));
        else {
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
          cimg_mp_func_name(ind,ptr,siz);
        }
        return cimg::type<double>::nan();
      }
#else
      static double mp_name(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_neq(_cimg_math_parser& mp) {
        return (double)(_mp_arg(2)!=_mp_arg(3));
      }

      static double mp_noise(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          siz = (unsigned int)mp.opcode[3],
          noise_type = (unsigned int)_mp_arg(5);
        const double
          *const ptrs = &_mp_arg(2) + 1,
          amplitude = _mp_arg(4);
        CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).get_noise(amplitude,noise_type);
        return cimg::type<double>::nan();
      }

      static double mp_noise_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          siz = (unsigned int)mp.opcode[3],
          noise_type = (unsigned int)_mp_arg(5);
        const double amplitude = _mp_arg(4);
        CImg<doubleT>(ptrs,siz,1,1,1,true).noise(amplitude,noise_type);
        return cimg::type<double>::nan();
      }

      static double mp_normalize(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double
          *const ptrs = &_mp_arg(2) + 1,
          min_value = _mp_arg(4),
          max_value = _mp_arg(5),
          constant_case_ratio = _mp_arg(6);
        CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).
          get_normalize(min_value,max_value,constant_case_ratio);
        return cimg::type<double>::nan();
      }

      static double mp_normalize_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double
          min_value = _mp_arg(4),
          max_value = _mp_arg(5),
          constant_case_ratio = _mp_arg(6);
        CImg<doubleT>(ptrs,siz,1,1,1,true).normalize(min_value,max_value,constant_case_ratio);
        return cimg::type<double>::nan();
      }

      static double mp_normp(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double p = _mp_arg(4);
        if (siz>0) { // Vector-valued argument
          const double *ptrs = &_mp_arg(2) + 1;
          double res = 0;
          if (p==2) { // L2
            for (unsigned int i = 0; i<siz; ++i) res+=(double)cimg::sqr(*(ptrs++));
            res = (double)std::sqrt(res);
          } else if (p==1) // L1
            for (unsigned int i = 0; i<siz; ++i) res+=(double)cimg::abs(*(ptrs++));
          else if (!p) // L0
            for (unsigned int i = 0; i<siz; ++i) res+=(double)(*(ptrs++)?1:0);
          else if (cimg::type<double>::is_inf(p)) { // L-inf
            for (unsigned int i = 0; i<siz; ++i) {
              const double val = (double)cimg::abs(*(ptrs++));
              if (val>res) res = val;
            }
          } else { // L-p
            for (unsigned int i = 0; i<siz; ++i) res+=(double)std::pow(cimg::abs(*(ptrs++)),p);
            res = (double)std::pow(res,1.0/p);
          }
          return res>0?res:0;
        }
        // Scalar-valued argument.
        const double val = _mp_arg(2);
        return p?cimg::abs(val):(val!=0);
      }

      static double mp_o2c(_cimg_math_parser& mp) {
        unsigned int ind = (unsigned int)mp.opcode[2];
        if (ind!=~0U) {
          mp_check_list(mp,"o2c");
          ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.imglist.width());
        }
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        double *ptrd = &_mp_arg(1) + 1;
        longT offset = (longT)_mp_arg(3);
        const bool boundary_conditions = (bool)_mp_arg(4);
        if (boundary_conditions && (!img || offset<0 || (ulongT)offset>=img.size()))
          ptrd[0] = ptrd[1] = ptrd[2] = ptrd[3] = -1;
        else {
          if (!img) ptrd[0] = ptrd[1] = ptrd[2] = ptrd[3] = cimg::type<double>::nan();
          else {
            *(ptrd++) = (double)(offset%img.width());
            offset/=img.width();
            *(ptrd++) = (double)(offset%img.height());
            offset/=img.height();
            *(ptrd++) = (double)(offset%img.depth());
            offset/=img.depth();
            *ptrd = (double)(offset%img.spectrum());
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_permutations(_cimg_math_parser& mp) {
        return cimg::permutations((int)_mp_arg(2),(int)_mp_arg(3),(bool)_mp_arg(4));
      }

      static double mp_permute(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double
          *const ptrs = &_mp_arg(2) + 1,
          *const ptrp = &_mp_arg(7) + 1;
        CImg<charT> str(sizp + 1);
        for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
        str.back() = 0;
        CImg<doubleT>(ptrd,wA,hA,dA,sA,true) = CImg<doubleT>(ptrs,wA,hA,dA,sA,true).
          get_permute_axes(str);
        return cimg::type<double>::nan();
      }

      static double mp_permute_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          sizp = (unsigned int)mp.opcode[8];
        const double *const ptrp = &_mp_arg(7) + 1;
        CImg<charT> str(sizp + 1);
        for (unsigned int p = 0; p<sizp; ++p) str[p] = (char)ptrp[p];
        str.back() = 0;
        CImg<doubleT>(ptrs,wA,hA,dA,sA,true).permute_axes(str);
        return cimg::type<double>::nan();
      }

      static double mp_polygon(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        unsigned int ind = (unsigned int)mp.opcode[3];
        if (ind!=~0U) {
          if (!mp.imglist.width()) return cimg::type<double>::nan();
          ind = (unsigned int)cimg::mod((int)_mp_arg(3),mp.imglist.width());
        }
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        bool is_invalid_arguments = i_end<=4, is_outlined = false, is_closed = true;
        if (!is_invalid_arguments) {
          int nbv = (int)_mp_arg(4);
          if (!nbv) is_invalid_arguments = true;
          else {
            if (nbv<0) { nbv = -nbv; is_outlined = true; }
            CImg<intT> points(nbv,2,1,1,0);
            CImg<T> color(img._spectrum,1,1,1,0);
            float opacity = 1;
            unsigned int i = 5, pattern=~0U;
            cimg_foroff(points,k) if (i<i_end) points(k/2,k%2) = (int)cimg::round(_mp_arg(i++));
            else { is_invalid_arguments = true; break; }
            if (!is_invalid_arguments) {
              if (i<i_end) opacity = (float)_mp_arg(i++);
              if (is_outlined && i<i_end) {
                double d_pattern = _mp_arg(i++);
                if (d_pattern<0) { d_pattern = -d_pattern; is_closed = false; }
                pattern = (unsigned int)d_pattern;
              }
              cimg_forX(color,k) if (i<i_end) color[k] = (T)_mp_arg(i++);
              else { color.resize(k,1,1,1,-1); break; }
              color.resize(img._spectrum,1,1,1,0,2);
              if (is_outlined) img.draw_polygon(points,color._data,opacity,pattern,is_closed);
              else img.draw_polygon(points,color._data,opacity);
            }
          }
        }
        if (is_invalid_arguments) {
          CImg<doubleT> args(i_end - 4);
          cimg_forX(args,k) args[k] = _mp_arg(4 + k);
          if (ind==~0U)
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'polygon()': "
                                        "Invalid arguments '%s'. ",
                                        mp.imgin.pixel_type(),args.value_string()._data);
          else
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'polygon()': "
                                        "Invalid arguments '#%u%s%s'. ",
                                        mp.imgin.pixel_type(),ind,args._width?",":"",args.value_string()._data);
        }
        return cimg::type<double>::nan();
      }

      static double mp_pow0_25(_cimg_math_parser& mp) {
        const double val = _mp_arg(2);
        return std::sqrt(std::sqrt(val));
      }

      static double mp_pow3(_cimg_math_parser& mp) {
        const double val = _mp_arg(2);
        return val*val*val;
      }

      static double mp_pow4(_cimg_math_parser& mp) {
        const double val = _mp_arg(2);
        return val*val*val*val;
      }

      static double mp_print(_cimg_math_parser& mp) {
        const double val = _mp_arg(1);
        const bool print_char = (bool)mp.opcode[3];
        cimg_pragma_openmp(critical(mp_print)) {
          CImg<charT> _expr(mp.opcode[2] - 4);
          const ulongT *ptrs = mp.opcode._data + 4;
          cimg_for(_expr,ptrd,char) *ptrd = (char)*(ptrs++);
          cimg::strellipsize(_expr);
          cimg::mutex(6);
          if (print_char)
            std::fprintf(cimg::output(),"\n[" cimg_appname "_math_parser] %s = %.17g = '%c'",
                         _expr._data,val,(int)val);
          else
            std::fprintf(cimg::output(),"\n[" cimg_appname "_math_parser] %s = %.17g",
                         _expr._data,val);
          std::fflush(cimg::output());
          cimg::mutex(6,0);
        }
        return val;
      }

      static double mp_prod(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double prod = 1;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) prod*=*(ptr++);
          } else prod*=_mp_arg(i);
        }
        return prod;
      }

      static double mp_prod2(_cimg_math_parser& mp) {
        return _mp_arg(2)*_mp_arg(3);
      }

      static double mp_repeat(_cimg_math_parser& mp) {
        const double nb_it = _mp_arg(2), nb_itm1 = nb_it - 1;
        double
          *const ptrc = mp.opcode[3]!=~0U?&_mp_arg(3):0,
          *const ptrs = &_mp_arg(1);
        const CImg<ulongT>
          *const p_body = ++mp.p_code,
          *const p_end = p_body + mp.opcode[4];

        if (nb_it>=1) {
          const unsigned int _break_type = mp.break_type;
          mp.break_type = 0;

          double it = 0;
          if (ptrc) { // Version with loop variable (3 arguments)
            while (it<=nb_itm1) {
              *ptrc = it;
              mp.eval(p_body,p_end);
              if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
              ++it;
            }
            *ptrc = it;
          } else // Version without loop variable (2 arguments)
            while (it<=nb_itm1) {
              mp.eval(p_body,p_end);
              if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
              ++it;
            }
          mp.break_type = _break_type;
        }

        mp.p_code = p_end - 1;
        return *ptrs;
      }

      static double mp_reverse(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).get_mirror('x');
        return cimg::type<double>::nan();
      }

      static double mp_reverse_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        CImg<doubleT>(ptrs,siz,1,1,1,true).mirror('x');
        return cimg::type<double>::nan();
      }

      static double mp_rot2d(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double theta = _mp_arg(2), ca = std::cos(theta), sa = std::sin(theta);
        ptrd[0] = ptrd[3] = ca; ptrd[1] = -sa; ptrd[2] = sa;
        return cimg::type<double>::nan();
      }

      static double mp_rot3d(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const float
          x = (float)_mp_arg(2),
          y = (float)_mp_arg(3),
          z = (float)_mp_arg(4),
          theta = (float)_mp_arg(5);
        CImg<doubleT>(ptrd,3,3,1,1,true) = CImg<doubleT>::rotation_matrix(x,y,z,theta*180/cimg::PI);
        return cimg::type<double>::nan();
      }

      static double mp_round(_cimg_math_parser& mp) {
        return cimg::round(_mp_arg(2),_mp_arg(3),(int)_mp_arg(4));
      }

      static double mp_vector_round(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const double *const ptrs = &_mp_arg(3) + 1, arg1 = _mp_arg(4);
        const int arg2 = (int)_mp_arg(5);
        for (unsigned int k = 0; k<siz; ++k) ptrd[k] = cimg::round(ptrs[k],arg1,arg2);
        return cimg::type<double>::nan();
      }

#ifdef cimg_mp_func_run
      static double mp_run(_cimg_math_parser& mp) {
        const unsigned int nb_args = (unsigned int)mp.opcode[2];
        CImgList<charT> _str;
        CImg<charT> it;
        for (unsigned int n = 0; n<nb_args; ++n) {
          const unsigned int siz = (unsigned int)mp.opcode[4 + 2*n];
          if (siz) { // Vector argument -> string
            const double *ptr = &_mp_arg(3 + 2*n) + 1;
            unsigned int l = 0;
            while (l<siz && ptr[l]) ++l;
            CImg<doubleT>(ptr,l,1,1,1,true).move_to(_str);
          } else { // Scalar argument -> number
            it.assign(24);
            cimg_snprintf(it,it._width,"%.17g",_mp_arg(3 + 2*n));
            CImg<charT>::string(it,false,true).move_to(_str);
          }
        }
        CImg(1,1,1,1,0).move_to(_str);
        CImg<charT> str = _str>'x';
#if cimg_use_openmp==0
        const unsigned int n_thread = 0;
#else
        const unsigned int n_thread = omp_get_thread_num();
#endif
        cimg_mp_func_run(str._data,n_thread && mp.is_noncritical_run);
        return cimg::type<double>::nan();
      }
#else
      static double mp_run(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_s2v(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(2);
        const ulongT siz = (ulongT)mp.opcode[3];
        longT ind = (longT)_mp_arg(4);
        const bool is_strict = (bool)_mp_arg(5);
        double val = cimg::type<double>::nan();
        if (ind<0 || ind>=(longT)siz) return val;
        if (!siz) return *ptrs>='0' && *ptrs<='9'?*ptrs - '0':val;

        CImg<charT> ss(siz + 1 - ind);
        ptrs+=1 + ind;
        cimg_forX(ss,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;

        const char *s = ss._data;
        while (*s && *s<=32) ++s;
        const bool is_negative = *s=='-';
        if (is_negative || *s=='+') ++s;
        int err = 0;
        char sep;
        if (*s=='0' && (s[1]=='x' || s[1]=='X') &&
            ((s[2]>='0' && s[2]<='9') || (s[2]>='a' && s[2]<='f') || (s[2]>='a' && s[2]<='f'))) { // Hexadecimal number
          val = (double)cimg::strtoll(s + 2,0,16);
          err = 1;
        } else if (*s=='0' && (s[1]=='b' || s[1]=='B') && (s[2]=='0' || s[2]=='1')) { // Binary number
          val = (double)cimg::strtoll(s + 2,0,2);
          err = 1;
        } else if (*s>32) { // Decimal number
          err = cimg_sscanf(s,"%lf%c",&val,&sep);
#if cimg_OS==2
          // Check for +/-NaN and +/-inf as Microsoft's sscanf() version is not able
          // to read those particular values.
          if (!err && (*s=='i' || *s=='I' || *s=='n' || *s=='N')) {
            if (!cimg::strncasecmp(s,"inf",3)) { val = cimg::type<double>::inf(); err = 1 + (s[3]!=0); }
            else if (!cimg::strncasecmp(s,"nan",3)) { val = cimg::type<double>::nan(); err = 1 + (s[3]!=0); }
          }
#endif
        }
        if (err<=0 || (is_strict && err!=1)) return cimg::type<double>::nan();
        if (is_negative) val = -val;
        return val;
      }

      static double mp_self_map_vector_s(_cimg_math_parser& mp) { // Vector += scalar
        unsigned int
          ptrd = (unsigned int)mp.opcode[1] + 1,
          siz = (unsigned int)mp.opcode[2];
        mp_func op = (mp_func)mp.opcode[3];
        ulongT l_data[3] = { 0 };
        CImg<ulongT> l_opcode(l_data,1,3,1,1,true);
        l_opcode[2] = mp.opcode[4]; // Scalar argument
        l_opcode.swap(mp.opcode);
        ulongT &target = mp.opcode[1];
        while (siz-->0) { target = ptrd++; (*op)(mp); }
        l_opcode.swap(mp.opcode);
        return cimg::type<double>::nan();
      }

      static double mp_self_map_vector_v(_cimg_math_parser& mp) { // Vector += vector
        unsigned int
          ptrd = (unsigned int)mp.opcode[1] + 1,
          siz = (unsigned int)mp.opcode[2],
          ptrs = (unsigned int)mp.opcode[4] + 1;
        mp_func op = (mp_func)mp.opcode[3];
        ulongT l_data[4] = { 0 };
        CImg<ulongT> l_opcode(l_data,1,4,1,1,true);
        l_opcode.swap(mp.opcode);
        ulongT &target = mp.opcode[1], &argument = mp.opcode[2];
        while (siz-->0) { target = ptrd++; argument = ptrs++; (*op)(mp); }
        l_opcode.swap(mp.opcode);
        return cimg::type<double>::nan();
      }

#ifdef cimg_mp_func_set
      static double mp_set(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(1);
        double *ptrd = &_mp_arg(3) + 1;
        const unsigned int
          sizs = (unsigned int)mp.opcode[2],
          sizd = (unsigned int)mp.opcode[4];
        CImg<charT> sd(sizd + 1);
        cimg_for_inX(sd,0,sd.width() - 2,i) sd[i] = (char)ptrd[i];
        sd.back() = 0;
        if (sizs) cimg_mp_func_set(ptrs + 1,sizs,sd._data);
        else cimg_mp_func_set(ptrs,0,sd._data);
        return *ptrs;
      }
#else
      static double mp_set(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_set_ijoff(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const longT
          off = (longT)(is_relative?img.offset((int)mp.mem[_cimg_mp_slot_x],
                                               (int)mp.mem[_cimg_mp_slot_y],
                                               (int)mp.mem[_cimg_mp_slot_z],
                                               (int)mp.mem[_cimg_mp_slot_c]) + _mp_arg(4):_mp_arg(4)),
          whds = (longT)img.size();
        const double val = _mp_arg(1);
        if (off>=0 && off<whds) img[off] = (T)val;
        return val;
      }

      static double mp_set_ijxyzc(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const int
          x = (int)(is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4)),
          y = (int)(is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5)),
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6)),
          c = (int)(is_relative?(mp.mem[_cimg_mp_slot_c] + _mp_arg(7)):_mp_arg(7));
        const double val = _mp_arg(1);
        if (img.containsXYZC(x,y,z,c)) img(x,y,z,c) = (T)val;
        return val;
      }

      static double mp_set_IJoff_s(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const longT
          off = (longT)(is_relative?img.offset((int)mp.mem[_cimg_mp_slot_x],
                                               (int)mp.mem[_cimg_mp_slot_y],
                                               (int)mp.mem[_cimg_mp_slot_z],
                                               (int)mp.mem[_cimg_mp_slot_c]) + _mp_arg(4):_mp_arg(4)),
          whd = (longT)img.width()*img.height()*img.depth();
        const T val = (T)_mp_arg(1);
        if (off>=0 && off<whd) {
          T *ptrd = &img[off];
          cimg_forC(img,c) { *ptrd = val; ptrd+=whd; }
        }
        return _mp_arg(1);
      }

      static double mp_set_IJoff_v(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const longT
          off = (longT)(is_relative?img.offset((int)mp.mem[_cimg_mp_slot_x],
                                               (int)mp.mem[_cimg_mp_slot_y],
                                               (int)mp.mem[_cimg_mp_slot_z],
                                               (int)mp.mem[_cimg_mp_slot_c]) + _mp_arg(4):_mp_arg(4)),
          whd = (longT)img.width()*img.height()*img.depth();
        const double *ptrs = &_mp_arg(1) + 1;
        if (off>=0 && off<whd) {
          const unsigned int siz = (unsigned int)mp.opcode[5];
          T *ptrd = &img[off];
          cimg_for_inC(img,0,siz - 1,c) { *ptrd = (T)*(ptrs++); ptrd+=whd; }
        }
        return cimg::type<double>::nan();
      }

      static double mp_set_IJxyz_s(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const int
          x = (int)(is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4)),
          y = (int)(is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5)),
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6));
        const T val = (T)_mp_arg(1);
        if (x>=0 && x<img.width() && y>=0 && y<img.height() && z>=0 && z<img.depth()) {
          T *ptrd = &img(x,y,z);
          const ulongT whd = (ulongT)img._width*img._height*img._depth;
          cimg_forC(img,c) { *ptrd = val; ptrd+=whd; }
        }
        return _mp_arg(1);
      }

      static double mp_set_IJxyz_v(_cimg_math_parser& mp) {
        const unsigned int _ind = (unsigned int)mp.opcode[3];
        if (_ind!=~0U && !mp.imglist.width()) return cimg::type<double>::nan();
        const unsigned int ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width());
        const bool is_relative = (bool)mp.opcode[2];
        CImg<T> &img = ind==~0U?mp.imgout:mp.imglist[ind];
        const int
          x = (int)(is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4)),
          y = (int)(is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5)),
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6));
        const double *ptrs = &_mp_arg(1) + 1;
        if (x>=0 && x<img.width() && y>=0 && y<img.height() && z>=0 && z<img.depth()) {
          const unsigned int siz = (unsigned int)mp.opcode[7];
          T *ptrd = &img(x,y,z);
          const ulongT whd = (ulongT)img._width*img._height*img._depth;
          cimg_for_inC(img,0,siz - 1,c) { *ptrd = (T)*(ptrs++); ptrd+=whd; }
        }
        return cimg::type<double>::nan();
      }

      static double mp_size_list(_cimg_math_parser& mp) {
        return (double)mp.imglist.width();
      }

      static double mp_softargmax(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        if (siz<2) return 0;
        const double *const ptrs = &_mp_arg(2) + 1, temperature = _mp_arg(4);
        CImg<doubleT> sm = CImg<doubleT>(ptrs,siz,1,1,1,true).get_softmax(temperature);
        double res = 0;
        cimg_forX(sm,x) res+=sm[x]*x;
        return res;
      }

      static double mp_softargmin(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        if (siz<2) return 0;
        const double *const ptrs = &_mp_arg(2) + 1, temperature = _mp_arg(4);
        CImg<doubleT> sm = CImg<doubleT>(ptrs,siz,1,1,1,true).get_softmin(temperature);
        double res = 0;
        cimg_forX(sm,x) res+=sm[x]*x;
        return res;
      }

      static double mp_softmax(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        if (!siz) return 1;
        const double *const ptrs = &_mp_arg(2) + 1, temperature = _mp_arg(4);
        double *const ptrd = &_mp_arg(1) + 1;
        CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).get_softmax(temperature);
        return cimg::type<double>::nan();
      }

      static double mp_softmin(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        if (!siz) return 1;
        const double *const ptrs = &_mp_arg(2) + 1, temperature = _mp_arg(4);
        double *const ptrd = &_mp_arg(1) + 1;
        CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).get_softmin(temperature);
        return cimg::type<double>::nan();
      }

      static double mp_solve(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double
          *ptr1 = &_mp_arg(2) + 1,
          *ptr2 = &_mp_arg(3) + 1;
        const unsigned int
          k = (unsigned int)mp.opcode[4],
          l = (unsigned int)mp.opcode[5],
          m = (unsigned int)mp.opcode[6];
        CImg<doubleT>(ptrd,m,k,1,1,true) = CImg<doubleT>(ptr2,m,l,1,1,false).
          solve(CImg<doubleT>(ptr1,k,l,1,1,true));
        return cimg::type<double>::nan();
      }

      static double mp_sort(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(2) + 1;
        const int
          siz = (int)mp.opcode[3],
          starting_index = (int)_mp_arg(5),
          nb_elts = mp.opcode[6]==~0U?siz:(int)_mp_arg(6),
          siz_elt = (int)_mp_arg(7),
          sort_index = (int)_mp_arg(8),
          end_index = starting_index + nb_elts*siz_elt;
        const bool is_increasing = (bool)_mp_arg(4);
        if (starting_index<0 || nb_elts<0 || siz_elt<=0 || sort_index<0 || sort_index>=siz_elt || end_index>siz)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'sort()': "
                                      "Invalid arguments 'starting_index=%g', 'nb_elts=%g', 'siz_elt=%g' and "
                                      "'sort_index=%g', for sorting a vector of size %u.",
                                      mp.imgin.pixel_type(),
                                      _mp_arg(5),mp.opcode[6]==~0U?siz:_mp_arg(6),_mp_arg(7),_mp_arg(8),siz);
        if (nb_elts) {
          if (starting_index>0) // Recopy left side
            std::memcpy(ptrd,ptrs,starting_index*sizeof(double));
          if (end_index<siz) // Recopy right side
            std::memcpy(ptrd + end_index,ptrs + end_index,(siz - end_index)*sizeof(double));

          // Sort region.
          CImg<doubleT>(ptrd + starting_index,siz_elt,nb_elts,1,1,true) =
            CImg<doubleT>(ptrs + starting_index,siz_elt,nb_elts,1,1,true).
            get_shift(-(int)sort_index,0,0,0,2).sort(is_increasing,siz_elt>1?'y':0).shift((int)sort_index,0,0,0,2);
        }
        return cimg::type<double>::nan();
      }

      static double mp_sort_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const int
          siz = (int)mp.opcode[3],
          starting_index = (int)_mp_arg(5),
          nb_elts = mp.opcode[6]==~0U?siz:(int)_mp_arg(6),
          siz_elt = (int)_mp_arg(7),
          sort_index = (int)_mp_arg(8),
          end_index = starting_index + nb_elts*siz_elt;
        const bool is_increasing = (bool)_mp_arg(4);
        if (starting_index<0 || nb_elts<0 || siz_elt<=0 || sort_index<0 || sort_index>=siz_elt || end_index>siz)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'sort()': "
                                      "Invalid arguments 'starting_index=%g', 'nb_elts=%g', 'siz_elt=%g' and "
                                      "'sort_index=%g', for sorting a vector of size %u.",
                                      mp.imgin.pixel_type(),
                                      _mp_arg(5),mp.opcode[6]==~0U?siz:_mp_arg(6),_mp_arg(7),_mp_arg(8),siz);
        if (nb_elts) {
          // Sort region.
          CImg<doubleT>(ptrs + starting_index,siz_elt,nb_elts,1,1,true).
            shift(-(int)sort_index,0,0,0,2).sort(is_increasing,siz_elt>1?'y':0).shift((int)sort_index,0,0,0,2);
        }
        return cimg::type<double>::nan();
      }

      static double mp_srand(_cimg_math_parser& mp) {
        mp.rng = (cimg_uint64)_mp_arg(2);
        return cimg::type<double>::nan();
      }

      static double mp_srand0(_cimg_math_parser& mp) {
        cimg::srand(&mp.rng);

#if cimg_use_openmp!=0
        mp.rng+=omp_get_thread_num();
#endif
        return cimg::type<double>::nan();
      }

      static double mp_std(_cimg_math_parser& mp) {
        return std::sqrt(mp_var(mp));
      }

      static double mp_std2(_cimg_math_parser& mp) {
        return std::sqrt(mp_var2(mp));
      }

#ifdef cimg_mp_func_store
      static double mp_store(_cimg_math_parser& mp) {
        const double
          *ptr1 = &_mp_arg(2),
          *ptr2 = &_mp_arg(4) + 1;
        const unsigned int
          siz1 = (unsigned int)mp.opcode[3],
          siz2 = (unsigned int)mp.opcode[5];
        const int
          w = (int)_mp_arg(6),
          h = (int)_mp_arg(7),
          d = (int)_mp_arg(8),
          s = (int)_mp_arg(9);

        const bool is_compressed = (bool)_mp_arg(10);
        if (w<0 || h<0 || d<0 || s<0)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'store()': "
                                      "Specified image dimensions (%d,%d,%d,%d) are invalid.",
                                      pixel_type(),w,h,d,s);
        CImg<charT> ss(siz2 + 1);
        cimg_for_inX(ss,0,ss.width() - 2,i) ss[i] = (char)ptr2[i];
        ss.back() = 0;
        if (siz1) cimg_mp_func_store(ptr1 + 1,siz1,
                                     (unsigned int)w,(unsigned int)h,(unsigned int)d,(unsigned int)s,
                                     is_compressed,ss._data);
        else cimg_mp_func_store(ptr1,1,(unsigned int)w,(unsigned int)h,(unsigned int)d,(unsigned int)s,
                                is_compressed,ss._data);
        return cimg::type<double>::nan();
      }
#else
      static double mp_store(_cimg_math_parser& mp) { cimg::unused(mp); return cimg::type<double>::nan(); }
#endif

      static double mp_string(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int nb_args = (unsigned int)mp.opcode[3];
        CImgList<charT> _str;
        CImg<charT> it;
        for (unsigned int n = 0; n<nb_args; ++n) {
          const unsigned int siz = (unsigned int)mp.opcode[5 + 2*n];
          if (siz) { // Vector argument -> string
            const double *ptr = &_mp_arg(4 + 2*n) + 1;
            unsigned int l = 0;
            while (l<siz && ptr[l]) ++l;
            CImg<doubleT>(ptr,l,1,1,1,true).move_to(_str);
          } else { // Scalar argument -> number
            it.assign(24);
            cimg_snprintf(it,it._width,"%.17g",_mp_arg(4 + 2*n));
            CImg<charT>::string(it,false,true).move_to(_str);
          }
        }
        const CImg<charT> str = _str>'x';
        const unsigned int sizd = std::min(str._width,(unsigned int)mp.opcode[2]);
        std::memset(ptrd,0,mp.opcode[2]*sizeof(double));
        for (unsigned int k = 0; k<sizd; ++k) ptrd[k] = (double)str[k];
        return cimg::type<double>::nan();
      }

      static double mp_string_init(_cimg_math_parser& mp) {
        const unsigned char *ptrs = (unsigned char*)&mp.opcode[3];
        unsigned int
          ptrd = (unsigned int)mp.opcode[1] + 1,
          siz = (unsigned int)mp.opcode[2];
        while (siz-->0) mp.mem[ptrd++] = (double)*(ptrs++);
        return cimg::type<double>::nan();
      }

      static double mp_sub_div(_cimg_math_parser& mp) {
        return _mp_arg(2) - _mp_arg(3)/_mp_arg(4);
      }

      static double mp_sub_mul(_cimg_math_parser& mp) {
        return _mp_arg(2) - _mp_arg(3)*_mp_arg(4);
      }

      static double mp_sub_sub(_cimg_math_parser& mp) {
        return _mp_arg(2) - _mp_arg(3) - _mp_arg(4);
      }

      static double mp_sum(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double sum = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) sum+=*(ptr++);
          } else sum+=_mp_arg(i);
        }
        return sum;
      }

      static double mp_sum2(_cimg_math_parser& mp) {
        return _mp_arg(2) + _mp_arg(3);
      }

      static double mp_swap(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        if (!siz) { // Scalar
          double &arg1 = _mp_arg(1), &arg2 = _mp_arg(2);
          cimg::swap(arg1,arg2);
        } else { // Vector
          double *const ptr1 = &_mp_arg(1) + 1, *const ptr2 = &_mp_arg(2) + 1;
          for (unsigned int k = 0; k<siz; ++k) cimg::swap(ptr1[k],ptr2[k]);
        }
        return _mp_arg(1);
      }

      static double mp_trace(_cimg_math_parser& mp) {
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int k = (unsigned int)mp.opcode[3];
        return CImg<doubleT>(ptrs,k,k,1,1,true).trace();
      }

      static double mp_transpose(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int
          k = (unsigned int)mp.opcode[3],
          l = (unsigned int)mp.opcode[4];
        CImg<doubleT>(ptrd,l,k,1,1,true) = CImg<doubleT>(ptrs,k,l,1,1,true).get_transpose();
        return cimg::type<double>::nan();
      }

      static double mp_rand_double_0_1(_cimg_math_parser& mp) {
        return (double)cimg::_rand(&mp.rng)/~0U;
      }

      static double mp_rand_double_0_N(_cimg_math_parser& mp) {
        return _mp_arg(2)*(double)cimg::_rand(&mp.rng)/~0U;
      }

      static double mp_rand_double_ext(_cimg_math_parser& mp) {
        const double eps = 1e-5;
        const bool include_min = (bool)_mp_arg(4), include_max = (bool)_mp_arg(5);
        double _m = _mp_arg(2), _M = _mp_arg(3);
        if (_m>_M) cimg::swap(_m,_M);
        const double
          m = include_min?_m:_m>0?_m*(1 + eps):_m<0?_m*(1 - eps):eps,
          M = include_max?_M:_M>0?_M*(1 - eps):_M<0?_M*(1 + eps):-eps;
        return m + (M - m)*(double)cimg::_rand(&mp.rng)/~0U;
      }

      static double mp_vector_rand_double_ext(_cimg_math_parser& mp) {
        const double eps = 1e-5;
        const unsigned int sizm = (unsigned int)mp.opcode[3], sizM = (unsigned int)mp.opcode[5];
        const bool include_min = (bool)_mp_arg(6), include_max = (bool)_mp_arg(7);
        double *const ptrd = &_mp_arg(1) + 1;
        if (!sizm && sizM) { // sv
          const double _m0 = _mp_arg(2), *const ptr1 = &_mp_arg(4) + 1;
          for (unsigned int k = 0; k<sizM; ++k) {
            double _m = _m0, _M = ptr1[k];
            if (_m>_M) cimg::swap(_m,_M);
            const double
              m = include_min?_m:_m>0?_m*(1 + eps):_m<0?_m*(1 - eps):eps,
              M = include_max?_M:_M>0?_M*(1 - eps):_M<0?_M*(1 + eps):-eps;
            ptrd[k] = m + (M - m)*(double)cimg::_rand(&mp.rng)/~0U;
          }
        } else if (sizm && !sizM) { // vs
          const double *const ptr0 = &_mp_arg(2) + 1, _M1 = _mp_arg(4);
          for (unsigned int k = 0; k<sizm; ++k) {
            double _m = ptr0[k], _M = _M1;
            if (_m>_M) cimg::swap(_m,_M);
            const double
              m = include_min?_m:_m>0?_m*(1 + eps):_m<0?_m*(1 - eps):eps,
              M = include_max?_M:_M>0?_M*(1 - eps):_M<0?_M*(1 + eps):-eps;
            ptrd[k] = m + (M - m)*(double)cimg::_rand(&mp.rng)/~0U;
          }
        } else { // vv
          const double *const ptr0 = &_mp_arg(2) + 1, *const ptr1 = &_mp_arg(4) + 1;
          for (unsigned int k = 0; k<sizm; ++k) {
            double _m = ptr0[k], _M = ptr1[k];
            if (_m>_M) cimg::swap(_m,_M);
            const double
              m = include_min?_m:_m>0?_m*(1 + eps):_m<0?_m*(1 - eps):eps,
              M = include_max?_M:_M>0?_M*(1 - eps):_M<0?_M*(1 + eps):-eps;
            ptrd[k] = m + (M - m)*(double)cimg::_rand(&mp.rng)/~0U;
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_rand_double_m1_1(_cimg_math_parser& mp) {
        return 2*(double)cimg::_rand(&mp.rng)/~0U - 1;
      }

      static double mp_rand_double_gaussian(_cimg_math_parser& mp) {
        return cimg::grand(&mp.rng);
      }

      static double mp_rand_int_0_1(_cimg_math_parser& mp) {
        return cimg::_rand(&mp.rng)<(~0U>>1);
      }

      double _rand_int_0_N(const cimg_uint64 range) {
        if (range>=cimg::type<cimg_uint64>::max()) return cimg::round(cimg::rand(0,range,&rng));
        if (!range) return 0;
        cimg_uint64 val = 0;
        do { val = (cimg_uint64)std::floor(cimg::rand(range + 1,&rng)); } while (val>range);
        return val;
      }

      static double mp_rand_int_0_N(_cimg_math_parser& mp) {
        const double range = _mp_arg(2);
        const int sgn = range>=0?1:-1;
        return sgn*mp._rand_int_0_N(range*sgn);
      }

      double _rand_int_m_M(const double arg0, const double arg1) {
        double _m = arg0, _M = arg1;
        if (_m>_M) cimg::swap(_m,_M);
        const cimg_int64
          m = cimg::type<cimg_int64>::cut(std::ceil(_m)),
          M = cimg::type<cimg_int64>::cut(std::floor(_M));
        return (double)(m + _rand_int_0_N(M - m));
      }

      static double mp_rand_int_ext(_cimg_math_parser& mp) {
        double _m = _mp_arg(2), _M = _mp_arg(3);
        const bool include_min = (bool)_mp_arg(4), include_max = (bool)_mp_arg(5);
        if (_m>_M) cimg::swap(_m,_M);
        const int
          m = cimg::type<cimg_uint64>::cut(std::ceil(_m)) + (include_min?0:1),
          M = cimg::type<cimg_uint64>::cut(std::floor(_M)) - (include_max?0:1);
        return (double)(m + mp._rand_int_0_N(M - m));
      }

      static double mp_vector_rand_int_ext(_cimg_math_parser& mp) {
        const unsigned int sizm = (unsigned int)mp.opcode[3], sizM = (unsigned int)mp.opcode[5];
        const bool include_min = (bool)_mp_arg(6), include_max = (bool)_mp_arg(7);
        double *const ptrd = &_mp_arg(1) + 1;
        if (!sizm && sizM) { // svss
          const double _m0 = _mp_arg(2), *const ptr1 = &_mp_arg(4) + 1;
          for (unsigned int k = 0; k<sizM; ++k) {
            double _m = _m0, _M = ptr1[k];
            if (_m>_M) cimg::swap(_m,_M);
            const int
              m = cimg::type<cimg_uint64>::cut(std::ceil(_m)) + (include_min?0:1),
              M = cimg::type<cimg_uint64>::cut(std::floor(_M)) - (include_max?0:1);
            ptrd[k] = (double)(m + mp._rand_int_0_N(M - m));
          }
        } else if (sizm && !sizM) { // vsss
          const double *const ptr0 = &_mp_arg(2) + 1, _M1 = _mp_arg(4);
          for (unsigned int k = 0; k<sizm; ++k) {
            double _m = ptr0[k], _M = _M1;
            if (_m>_M) cimg::swap(_m,_M);
            const int
              m = cimg::type<cimg_uint64>::cut(std::ceil(_m)) + (include_min?0:1),
              M = cimg::type<cimg_uint64>::cut(std::floor(_M)) - (include_max?0:1);
            ptrd[k] = (double)(m + mp._rand_int_0_N(M - m));
          }
        } else { // vvss
          const double *const ptr0 = &_mp_arg(2) + 1, *const ptr1 = &_mp_arg(4) + 1;
          for (unsigned int k = 0; k<sizm; ++k) {
            double _m = ptr0[k], _M = ptr1[k];
            if (_m>_M) cimg::swap(_m,_M);
            const int
              m = cimg::type<cimg_uint64>::cut(std::ceil(_m)) + (include_min?0:1),
              M = cimg::type<cimg_uint64>::cut(std::floor(_M)) - (include_max?0:1);
            ptrd[k] = (double)(m + mp._rand_int_0_N(M - m));
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_rand_int_m1_1(_cimg_math_parser& mp) {
        const unsigned int
          th = ~0U/3,
          val = cimg::_rand(&mp.rng);
        return val<th?-1:val<2*th?0:1;
      }

      static double mp_unitnorm(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const double p = _mp_arg(4);
        if (siz>0) { // Vector-valued argument
          double *const ptrd = &_mp_arg(1) + 1;
          const double *const ptrs = &_mp_arg(2) + 1;
          if (ptrd!=ptrs) std::memcpy(ptrd,ptrs,siz*sizeof(double));
          CImg<doubleT> vec(ptrd,siz,1,1,1,true);
          const double mag = vec.magnitude(p);
          if (mag>0) vec/=mag;
          return cimg::type<double>::nan();
        }
        // Scalar-valued argument.
        const double val = _mp_arg(2);
        return val?(_mp_arg(2)?1:val):0;
      }

      static double mp_v2s(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int
          sizd = (unsigned int)mp.opcode[2],
          sizs = (unsigned int)mp.opcode[4];
        std::memset(ptrd,0,sizd*sizeof(double));
        const int nb_digits = (int)_mp_arg(5);
        CImg<charT> format(32);
        switch (nb_digits) {
        case -1 : std::strcpy(format,"%g"); break;
        case 0 : std::strcpy(format,"%.17g"); break;
        default :
          if (nb_digits>=-1) cimg_snprintf(format,format._width,"%%.%dg",nb_digits);
          else cimg_snprintf(format,format._width,"%%.%dld",-nb_digits);
        }
        CImg<charT> str;
        if (sizs) { // Vector expression
          const double *ptrs = &_mp_arg(3) + 1;
          if (nb_digits>=-1) CImg<doubleT>(ptrs,sizs,1,1,1,true).value_string(',',sizd + 1,format).move_to(str);
          else CImg<longT>(ptrs,sizs,1,1,1).value_string(',',sizd + 1,format).move_to(str);
        } else { // Scalar expression
          str.assign(sizd + 1);
          if (nb_digits>=-1) cimg_snprintf(str,sizd + 1,format,_mp_arg(3));
          else cimg_snprintf(str,sizd + 1,format,(long)_mp_arg(3));
        }
        const unsigned int l = std::min(sizd,(unsigned int)std::strlen(str) + 1);
        CImg<doubleT>(ptrd,l,1,1,1,true) = str.get_shared_points(0,l - 1);
        return cimg::type<double>::nan();
      }

      static double mp_var(_cimg_math_parser& mp) {
        const unsigned int i_end = (unsigned int)mp.opcode[2];
        double m = 0, S2 = 0;
        ulongT n = 0;
        for (unsigned int i = 3; i<i_end; i+=2) {
          const unsigned int len = (unsigned int)mp.opcode[i + 1];
          if (len>1) {
            const double *ptr = &_mp_arg(i);
            for (unsigned int k = 0; k<len; ++k) {
              const double val = *(ptr++), delta = val - m;
              m+=delta/++n;
              const double delta2 = val - m;
              S2+=delta*delta2;
            }
          } else {
            const double val = _mp_arg(i), delta = val - m;
            m+=delta/++n;
            const double delta2 = val - m;
            S2+=delta*delta2;
          }
        }
        return n<2?0.:std::max(S2/n,0.);
      }

      static double mp_var2(_cimg_math_parser& mp) {
        return cimg::sqr(_mp_arg(2) - _mp_arg(3))/2;
      }

#define _cimg_mp_vfunc(func) \
      const longT sizd = (longT)mp.opcode[2]; \
      const unsigned int nbargs = (unsigned int)mp.opcode[3]; \
      double *const ptrd = &_mp_arg(1) + (sizd?1:0); \
      cimg_pragma_openmp(parallel cimg_openmp_if_size(sizd,256)) { \
        CImg<doubleT> vec(nbargs); double res; \
        cimg_pragma_openmp(for) for (longT k = sizd?sizd - 1:0; k>=0; --k) { \
          cimg_forX(vec,n) vec[n] = *(&_mp_arg(4 + 2*n) + (k+1)*(mp.opcode[4 + 2*n + 1]?1:0)); \
          func; ptrd[k] = res; \
        }} \
      return sizd?cimg::type<double>::nan():*ptrd;

      static double _mp_vargkth(CImg<doubleT>& vec) {
        const double val = (+vec).get_shared_points(1,vec.width() - 1).
          kth_smallest((ulongT)cimg::cut((longT)*vec - 1,(longT)0,(longT)vec.width() - 2));
        cimg_for_inX(vec,1,vec.width() - 1,ind) if (vec[ind]==val) return ind - 1.;
        return 1.;
      }

      static double mp_vargkth(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = _mp_vargkth(vec));
      }

      static double mp_vargmax(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.max() - vec.data()));
      }

      static double mp_vargmaxabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.maxabs() - vec.data()));
      }

      static double mp_vargmin(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.min() - vec.data()));
      }

      static double mp_vargminabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = (double)(&vec.minabs() - vec.data()));
      }

      static double mp_vavg(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.mean());
      }

      static double mp_vector_copy(_cimg_math_parser& mp) {
        std::memcpy(&_mp_arg(1) + 1,&_mp_arg(2) + 1,sizeof(double)*mp.opcode[3]);
        return cimg::type<double>::nan();
      }

      static double mp_vector_crop(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptrs = &_mp_arg(2) + 1;
        const longT
          length = (longT)mp.opcode[3],
          start = (longT)_mp_arg(4),
          sublength = (longT)mp.opcode[5],
          step = (longT)_mp_arg(6);
        if (start<0 || start + step*(sublength-1)>=length)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Value accessor '[]': "
                                      "Out-of-bounds sub-vector request "
                                      "(length: %ld, start: %ld, sub-length: %ld, step: %ld).",
                                      mp.imgin.pixel_type(),length,start,sublength,step);
        ptrs+=start;
        if (step==1) std::memcpy(ptrd,ptrs,sublength*sizeof(double));
        else for (longT k = 0; k<sublength; ++k) { *(ptrd++) = *ptrs; ptrs+=step; }
        return cimg::type<double>::nan();
      }

      static double mp_vector_crop_ext(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[3],
          h = (unsigned int)mp.opcode[4],
          d = (unsigned int)mp.opcode[5],
          s = (unsigned int)mp.opcode[6],
          dx = (unsigned int)mp.opcode[11],
          dy = (unsigned int)mp.opcode[12],
          dz = (unsigned int)mp.opcode[13],
          dc = (unsigned int)mp.opcode[14],
          boundary_conditions = (int)_mp_arg(15);
        const int x = (int)_mp_arg(7), y = (int)_mp_arg(8), z = (int)_mp_arg(9), c = (int)_mp_arg(10);
        CImg<doubleT>(ptrd,dx,dy,dz,dc,true) = CImg<doubleT>(ptrs,w,h,d,s,true).
          get_crop(x,y,z,c,x + dx - 1,y + dy - 1,z + dz - 1,c + dc - 1,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_vector_display(_cimg_math_parser& mp) {
        const unsigned long
          _siz = (unsigned long)mp.opcode[3],
          siz = _siz?_siz:1;
        const double *const ptr = &_mp_arg(1) + (_siz?1:0);
        const int
          w = (int)_mp_arg(4),
          h = (int)_mp_arg(5),
          d = (int)_mp_arg(6),
          s = (int)_mp_arg(7);
        CImg<doubleT> img;
        if (w>0 && h>0 && d>0 && s>0) {
          if ((unsigned long)w*h*d*s!=siz)
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'display()': "
                                        "Invalid request to display a vector of size #%lu as a (%d,%d,%d,%d) image "
                                        "(%lu values).",
                                        mp.imgin.pixel_type(),siz,w,h,d,s,(unsigned long)w*h*d*s);
          img.assign(ptr,w,h,d,s,true);
        } else img.assign(ptr,1,siz,1,1,true);

        CImg<charT> expr(mp.opcode[2]);
        const ulongT *ptrs = mp.opcode._data + 8;
        cimg_for(expr,ptrd,char) *ptrd = (char)*(ptrs++);
        ((CImg<charT>::string("[" cimg_appname "_math_parser] ",false,true),expr)>'x').move_to(expr);
        cimg::strellipsize(expr);
        std::fputc('\n',cimg::output());
        img.display(expr._data);
        return cimg::type<double>::nan();
      }

      static double mp_vector_draw(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(7) + 1;
        const unsigned int
          sizD = (unsigned int)mp.opcode[2],
          sizS = (unsigned int)mp.opcode[8];
        const int
          w = (int)_mp_arg(3), h = (int)_mp_arg(4), d = (int)_mp_arg(5), s = (int)_mp_arg(6),
          x = (int)_mp_arg(9), y = (int)_mp_arg(10), z = (int)_mp_arg(11), c = (int)_mp_arg(12);
        int dx = (int)mp.opcode[13], dy = (int)mp.opcode[14], dz = (int)mp.opcode[15], dc = (int)mp.opcode[16];
        dx = (unsigned int)dx==~0U?w:(int)_mp_arg(13);
        dy = (unsigned int)dy==~0U?h:(int)_mp_arg(14);
        dz = (unsigned int)dz==~0U?d:(int)_mp_arg(15);
        dc = (unsigned int)dc==~0U?s:(int)_mp_arg(16);

        if (w<=0 || h<=0 || d<=0 || s<=0)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                      "Invalid specified target vector geometry (%d,%d,%d,%d).",
                                      mp.imgin.pixel_type(),w,h,d,s);
        if (sizD<(ulongT)w*h*d*s)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                      "Target vector (%lu values) and its specified target geometry (%d,%d,%d,%d) "
                                      "(%lu values) do not match.",
                                      mp.imgin.pixel_type(),sizD,w,h,d,s,(ulongT)w*h*d*s);
        if (dx<=0 || dy<=0 || dz<=0 || dc<=0)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                      "Invalid specified sprite geometry (%d,%d,%d,%d).",
                                      mp.imgin.pixel_type(),dx,dy,dz,dc);
        if (sizS<(ulongT)dx*dy*dz*dc)
          throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                      "Sprite vector (%lu values) and its specified sprite geometry (%d,%d,%d,%d) "
                                      "(%lu values) do not match.",
                                      mp.imgin.pixel_type(),sizS,dx,dy,dz,dc,(ulongT)dx*dy*dz*dc);

        CImg<doubleT> D(ptrd,w,h,d,s,true);
        const CImg<doubleT> S(ptrs,dx,dy,dz,dc,true);
        const float opacity = (float)_mp_arg(17);

        if (mp.opcode[18]!=~0U) { // Opacity mask specified
          const ulongT sizM = mp.opcode[19];
          if (sizM<(ulongT)dx*dy*dz)
            throw CImgArgumentException("[" cimg_appname "_math_parser] CImg<%s>: Function 'draw()': "
                                        "Mask vector (%lu values) and specified sprite geometry (%u,%u,%u,%u) "
                                        "(%lu values) do not match.",
                                        mp.imgin.pixel_type(),sizS,dx,dy,dz,dc,(ulongT)dx*dy*dz*dc);
          const CImg<doubleT> M(&_mp_arg(18) + 1,dx,dy,dz,(unsigned int)(sizM/(dx*dy*dz)),true);
          D.draw_image(x,y,z,c,S,M,opacity,(float)_mp_arg(20));
        } else D.draw_image(x,y,z,c,S,opacity);

        return cimg::type<double>::nan();
      }

      static double mp_vector_eq(_cimg_math_parser& mp) {
        const double
          *ptr1 = &_mp_arg(2) + 1,
          *ptr2 = &_mp_arg(4) + 1;
        unsigned int
          siz1 = (unsigned int)mp.opcode[3],
          siz2 = (unsigned int)mp.opcode[5],
          n;
        int N = (int)_mp_arg(6);
        const bool case_sensitive = (bool)_mp_arg(7);
        if (!N) return 1;
        if (N<0) { // Compare all values
          if (siz1>0 && siz2>0 && siz1!=siz2) return 0;
          N = std::max(siz1,siz2);
        }

        // Compare first N values.
        bool still_equal = true;
        if (siz1>0 && siz2>0) { // Vector==vector
          n = cimg::min((unsigned int)N,siz1,siz2);
          if (case_sensitive)
            while (still_equal && n--) {
              still_equal = (cimg::type<double>::is_nan(*ptr1) && cimg::type<double>::is_nan(*ptr2)) ||
                *ptr1==*ptr2;
              ++ptr1; ++ptr2;
            }
          else
            while (still_equal && n--) {
              still_equal = (cimg::type<double>::is_nan(*ptr1) && cimg::type<double>::is_nan(*ptr2)) ||
                cimg::lowercase(*ptr1)==cimg::lowercase(*ptr2);
              ++ptr1; ++ptr2;
            }
          return still_equal;
        } else if (siz1>0 && !siz2) { // Vector==scalar
          n = std::min((unsigned int)N,siz1);
          const double value = case_sensitive?_mp_arg(4):cimg::lowercase(_mp_arg(4));
          if (cimg::type<double>::is_nan(value))
            while (still_equal && n--) still_equal = cimg::type<double>::is_nan(*(ptr1++));
          else
            while (still_equal && n--) still_equal = *(ptr1++)==value;
          return still_equal;
        } else if (!siz1 && siz2>0) { // Scalar==vector
          n = std::min((unsigned int)N,siz2);
          const double value = case_sensitive?_mp_arg(2):cimg::lowercase(_mp_arg(2));
          if (cimg::type<double>::is_nan(value))
            while (still_equal && siz2--) still_equal = cimg::type<double>::is_nan(*(ptr2++));
          else
            while (still_equal && n--) still_equal = *(ptr2++)==value;
          return still_equal;
        } // Scalar==scalar
        if (case_sensitive) return _mp_arg(2)==_mp_arg(4);
        else if (cimg::type<double>::is_nan(_mp_arg(2))) return cimg::type<double>::is_nan(_mp_arg(4));
        return cimg::lowercase(_mp_arg(2))==cimg::lowercase(_mp_arg(4));
      }

      static double mp_vector_fill(_cimg_math_parser& mp) {
        double
          *ptrd = &_mp_arg(1) + 1,
          *const ptrc = mp.opcode[3]!=~0U?&_mp_arg(3):0,
          *const ptrs = &_mp_arg(4);
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const CImg<ulongT>
          *const p_body = ++mp.p_code,
          *const p_end = p_body + mp.opcode[5];
        const unsigned int _break_type = mp.break_type;
        mp.break_type = 0;

        unsigned int it = 0;
        if (ptrc) { // Version with loop variable (3 arguments)
          while (it<siz) {
            *ptrc = (double)it;
            mp.eval(p_body,p_end);
            if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
            else ptrd[it] = *ptrs;
            ++it;
          }
          *ptrc = (double)it;
        } else // Version without loop variable (2 arguments)
          while (it<siz) {
            mp.eval(p_body,p_end);
            if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
            else ptrd[it] = *ptrs;
            ++it;
          }
        mp.break_type = _break_type;
        mp.p_code = p_end - 1;
        return *ptrd;
      }

      static double mp_vector_fill_ext(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[2],
          h = (unsigned int)mp.opcode[3],
          d = (unsigned int)mp.opcode[4],
          s = (unsigned int)mp.opcode[5],
          sizs = (unsigned int)mp.opcode[7];
        const double *const ptrs = &_mp_arg(6) + 1;
        CImg<charT> ss(sizs + 1);
        cimg_for_inX(ss,0,ss.width() - 2,i) ss[i] = (char)ptrs[i];
        ss.back() = 0;
        CImg<doubleT>(ptrd,w,h,d,s,true)._fill(ss,true,3,&mp.imglist,"mp_image_fill",0,0);
        return cimg::type<double>::nan();
      }

      static double mp_vector_hypot(_cimg_math_parser& mp) {
        switch ((unsigned int)mp.opcode[2]) {
        case 5 : return cimg::abs(_mp_arg(4));
        case 6 : return cimg::hypot(_mp_arg(4),_mp_arg(5));
        case 7 : return cimg::hypot(_mp_arg(4),_mp_arg(5),_mp_arg(6));
        };
        return mp_vector_norm2(mp);
      }

      static double mp_vector_init(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        unsigned int sizd = (unsigned int)mp.opcode[2];
        const unsigned int nb_args = (unsigned int)mp.opcode[3];

        if (!nb_args) std::memset(ptrd,0,sizd*sizeof(double)); // 0 elements specified: Fill with 0
        else {
          unsigned int siz = (unsigned int)mp.opcode[5];
          if (nb_args==1 && siz<=1) { // A single scalar (or vector1) element specified
            const double val = siz?mp.mem[mp.opcode[4] + 1]:_mp_arg(4); while (sizd-->0) *(ptrd++) = val;
          } else {
            unsigned int n = 0, k = 4;
            while (sizd) {
              siz = (unsigned int)mp.opcode[k + 1];
              if (siz) { // Vector
                const unsigned int N = std::min(siz,sizd);
                std::memcpy(ptrd,&_mp_arg(k) + 1,N*sizeof(double));
                ptrd+=siz;
                sizd-=N;
              } else { // Scalar
                *(ptrd++) = _mp_arg(k);
                --sizd;
              }
              k+=2;
              if (++n>=nb_args) { n = 0; k = 4; }
            }
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_lerp(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        unsigned int siz = (unsigned int)mp.opcode[2];
        const unsigned int
          siz0 = (unsigned int)mp.opcode[4],
          siz1 = (unsigned int)mp.opcode[6],
          step0 = siz0?1:0,
          step1 = siz1?1:0;
        const double
          *const ptrs0 = &_mp_arg(3) + step0,
          *const ptrs1 = &_mp_arg(5) + step1;

        if (mp.opcode[8]) { // t is vector-valued
          const double *const ptrt = &_mp_arg(7) + 1;
          for (unsigned int k0 = 0, k1 = 0, k = 0; k<siz; ++k) {
            double t = ptrt[k];
            ptrd[k] = ptrs0[k0]*(1 - t) + ptrs1[k1]*t;
            k0+=step0;
            k1+=step1;
          }
        } else { // t is scalar-valued
          const double t = _mp_arg(7);
          for (unsigned int k0 = 0, k1 = 0, k = 0; k<siz; ++k) {
            ptrd[k] = ptrs0[k0]*(1 - t) + ptrs1[k1]*t;
            k0+=step0;
            k1+=step1;
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_neq(_cimg_math_parser& mp) {
        return !mp_vector_eq(mp);
      }

      static double mp_vector_norm0(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[2];
        double res = 0;
        for (unsigned int i = siz - 1; i>3; --i) res+=(double)(_mp_arg(i)?1:0);
        return res;
      }

      static double mp_vector_norm1(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[2];
        double res = 0;
        for (unsigned int i = siz - 1; i>3; --i) res+=(double)cimg::abs(_mp_arg(i));
        return res;
      }

      static double mp_vector_norm2(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[2];
        double res = 0;
        for (unsigned int i = siz - 1; i>3; --i) res+=(double)cimg::sqr(_mp_arg(i));
        return (double)std::sqrt(res);
      }

      static double mp_vector_norminf(_cimg_math_parser& mp) {
        const unsigned int siz = (unsigned int)mp.opcode[2];
        double res = 0;
        for (unsigned int i = siz - 1; i>3; --i) {
          const double val = (double)cimg::abs(_mp_arg(i));
          if (val>res) res = val;
        }
        return res;
      }

      static double mp_vector_off(_cimg_math_parser& mp) {
        const unsigned int
          ptr = (unsigned int)mp.opcode[2] + 1,
          siz = (unsigned int)mp.opcode[3];
        const int off = (int)_mp_arg(4);
        return off>=0 && off<(int)siz?mp.mem[ptr + off]:cimg::type<double>::nan();
      }

      static double mp_vector_print(_cimg_math_parser& mp) {
        const bool print_string = (bool)mp.opcode[4];
        cimg_pragma_openmp(critical(mp_vector_print)) {
          CImg<charT> _expr(mp.opcode[2] - 5);
          const ulongT *ptrs = mp.opcode._data + 5;
          cimg_for(_expr,ptrd,char) *ptrd = (char)*(ptrs++);
          cimg::strellipsize(_expr);
          unsigned int
            ptr = (unsigned int)mp.opcode[1] + 1,
            siz0 = (unsigned int)mp.opcode[3],
            siz = siz0;
          cimg::mutex(6);
          std::fprintf(cimg::output(),"\n[" cimg_appname "_math_parser] %s = [ ",_expr._data);
          unsigned int count = 0;
          while (siz-->0) {
            if (count>=64 && siz>=64) {
              std::fprintf(cimg::output(),"...,");
              ptr = (unsigned int)mp.opcode[1] + 1 + siz0 - 64;
              siz = 64;
            } else std::fprintf(cimg::output(),"%.17g%s",mp.mem[ptr++],siz?",":"");
            ++count;
          }
          if (print_string) {
            CImg<charT> str(siz0 + 1);
            ptr = (unsigned int)mp.opcode[1] + 1;
            for (unsigned int k = 0; k<siz0; ++k) str[k] = (char)mp.mem[ptr++];
            str[siz0] = 0;
            cimg::strellipsize(str,1024,false);
            std::fprintf(cimg::output()," ] = '%s' (size: %u)",str._data,siz0);
          } else std::fprintf(cimg::output()," ] (size: %u)",siz0);
          std::fflush(cimg::output());
          cimg::mutex(6,0);
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_rand(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptr_pdf = (unsigned int)mp.opcode[5]!=~0U?&_mp_arg(5) + 1:0;
        const unsigned int
          siz = (unsigned int)mp.opcode[2],
          siz_pdf = (unsigned int)mp.opcode[6],
          prec = (unsigned int)mp.opcode[7]!=~0U?(unsigned int)std::abs(_mp_arg(7)):65536;
        const double
          val_min = _mp_arg(3),
          val_max = _mp_arg(4);
        if (!ptr_pdf)
          CImg<doubleT>(ptrd,siz,1,1,1,true).rand(val_min,val_max);
        else {
          CImg<doubleT> pdf(ptr_pdf,siz_pdf,1,1,1,true);
          CImg<doubleT>(ptrd,siz,1,1,1,true).rand(val_min,val_max,pdf,prec);
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_resize(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int target_siz = (unsigned int)mp.opcode[2], initial_siz = (unsigned int)mp.opcode[4];
        const int
          interpolation = (int)_mp_arg(5),
          boundary_conditions = (int)_mp_arg(6);
        if (initial_siz) { // Resize vector
          const double *const ptrs = &_mp_arg(3) + 1;
          CImg<doubleT>(ptrd,target_siz,1,1,1,true) = CImg<doubleT>(ptrs,initial_siz,1,1,1,true).
            get_resize(target_siz,1,1,1,interpolation,boundary_conditions);
        } else { // Resize scalar
          const double value = _mp_arg(3);
          CImg<doubleT>(ptrd,target_siz,1,1,1,true) = CImg<doubleT>(1,1,1,1,value).
            resize(target_siz,1,1,1,interpolation,boundary_conditions);
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_resize_ext(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          siz = (unsigned int)mp.opcode[2],
          ow = (unsigned int)mp.opcode[4],
          oh = (unsigned int)mp.opcode[5],
          od = (unsigned int)mp.opcode[6],
          os = (unsigned int)mp.opcode[7],
          nw = (unsigned int)mp.opcode[8],
          nh = (unsigned int)mp.opcode[9],
          nd = (unsigned int)mp.opcode[10],
          ns = (unsigned int)mp.opcode[11];
        const int
          interpolation = (int)_mp_arg(12),
          boundary_conditions = (int)_mp_arg(13);
        const float
          ax = (float)_mp_arg(14),
          ay = (float)_mp_arg(15),
          az = (float)_mp_arg(16),
          ac = (float)_mp_arg(17);
        if (siz) { // Resize vector
          const double *const ptrs = &_mp_arg(3) + 1;
          CImg<doubleT>(ptrd,nw,nh,nd,ns,true) = CImg<doubleT>(ptrs,ow,oh,od,os,true).
            get_resize(nw,nh,nd,ns,interpolation,boundary_conditions,ax,ay,az,ac);
        } else { // Resize scalar
          const double value = _mp_arg(3);
          CImg<doubleT>(ptrd,nw,nh,nd,ns,true) = CImg<doubleT>(1,1,1,1,value).
            resize(nw,nh,nd,ns,interpolation,boundary_conditions,ax,ay,az,ac);
        }
        return cimg::type<double>::nan();
      }

      static double mp_vector_set_off(_cimg_math_parser& mp) {
        const unsigned int
          ptr = (unsigned int)mp.opcode[2] + 1,
          siz = (unsigned int)mp.opcode[3];
        const int off = (int)_mp_arg(4);
        if (off>=0 && off<(int)siz) mp.mem[ptr + off] = _mp_arg(1);
        return _mp_arg(1);
      }

      static double mp_shift(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const int
          shift = (int)_mp_arg(4),
          boundary_conditions = (int)_mp_arg(5);
        CImg<doubleT>(ptrd,siz,1,1,1,true) =
          CImg<doubleT>(ptrs,siz,1,1,1,true).get_shift(shift,0,0,0,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_shift_ip(_cimg_math_parser& mp) { // In-place version
        double *const ptrs = &_mp_arg(2) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[3];
        const int
          shift = (int)_mp_arg(4),
          boundary_conditions = (int)_mp_arg(5);
        CImg<doubleT>(ptrs,siz,1,1,1,true).shift(shift,0,0,0,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_vector_stats(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const double *ptrs = &_mp_arg(2) + 1;
        const unsigned int
          w = (unsigned int)mp.opcode[3],
          h = (unsigned int)mp.opcode[4],
          d = (unsigned int)mp.opcode[5],
          s = (unsigned int)mp.opcode[6];
        CImg<doubleT>(ptrd,15,1,1,1,true) = CImg<doubleT>(ptrs,w,h,d,s,true).get_stats();
        return cimg::type<double>::nan();
      }

      static double mp_vkth(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.get_shared_points(1,vec.width() - 1).
                       kth_smallest((ulongT)cimg::cut((longT)*vec - 1,(longT)0,(longT)vec.width() - 2)));
      }

      static double mp_vmax(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.max());
      }

      static double mp_vmaxabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.maxabs());
      }

      static double mp_vmedian(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.median());
      }

      static double mp_vmin(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.min());
      }

      static double mp_vminabs(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.minabs());
      }

      static double mp_vprod(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.product());
      }

      static double mp_vstd(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = std::sqrt(vec.get_stats()[3]));
      }

      static double mp_vsum(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.sum());
      }

      static double mp_vvar(_cimg_math_parser& mp) {
        _cimg_mp_vfunc(res = vec.get_stats()[3]);
      }

      static double mp_warp(_cimg_math_parser& mp) {
        double *const ptrd = &_mp_arg(1) + 1;
        const unsigned int
          wA = (unsigned int)mp.opcode[3],
          hA = (unsigned int)mp.opcode[4],
          dA = (unsigned int)mp.opcode[5],
          sA = (unsigned int)mp.opcode[6],
          wB = (unsigned int)mp.opcode[8],
          hB = (unsigned int)mp.opcode[9],
          dB = (unsigned int)mp.opcode[10],
          sB = (unsigned int)mp.opcode[11];
        const int
          mode = (int)_mp_arg(12),
          interpolation = (int)_mp_arg(13),
          boundary_conditions = (int)_mp_arg(14);
        const double
          *const ptrs = &_mp_arg(2) + 1,
          *const ptrw = &_mp_arg(7) + 1;
        CImg<doubleT>(ptrd,wB,hB,dB,sA,true) = CImg<doubleT>(ptrs,wA,hA,dA,sA,true).
          get_warp(CImg<doubleT>(ptrw,wB,hB,dB,sB,true),mode,interpolation,boundary_conditions);
        return cimg::type<double>::nan();
      }

      static double mp_while(_cimg_math_parser& mp) {
        const ulongT
          mem_body = mp.opcode[1],
          mem_cond = mp.opcode[2];
        const CImg<ulongT>
          *const p_cond = ++mp.p_code,
          *const p_body = p_cond + mp.opcode[3],
          *const p_end = p_body + mp.opcode[4];
        const unsigned int siz = (unsigned int)mp.opcode[5];
        bool is_cond = false;
        if (mp.opcode[6]) { // Set default value for result and condition if necessary
          if (siz) CImg<doubleT>(&mp.mem[mem_body] + 1,siz,1,1,1,true).fill(cimg::type<double>::nan());
          else mp.mem[mem_body] = cimg::type<double>::nan();
        }
        if (mp.opcode[7]) mp.mem[mem_cond] = 0;
        const unsigned int _break_type = mp.break_type;
        mp.break_type = 0;
        do {
          mp.eval(p_cond,p_body); // Evaluate condition
          if (mp.break_type==1) break;
          is_cond = (bool)mp.mem[mem_cond];
          if (is_cond && !mp.break_type) mp.eval(p_body,p_end); // Evaluate body
          if (mp.break_type==1) break; else if (mp.break_type==2) mp.break_type = 0;
        } while (is_cond);

        mp.break_type = _break_type;
        mp.p_code = p_end - 1;
        return mp.mem[mem_body];
      }

      static double mp_I(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const unsigned int siz = (unsigned int)mp.opcode[2];
        const CImg<T> &img = mp.imgin;
        if (img) {
          const longT whd = (longT)img.width()*img.height()*img.depth();
          const int
            x = (int)mp.mem[_cimg_mp_slot_x],
            y = (int)mp.mem[_cimg_mp_slot_y],
            z = (int)mp.mem[_cimg_mp_slot_z];
          const T *ptrs = img.data(x,y,z);
          cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
        } else std::memset(ptrd,0,siz*sizeof(double));
        return cimg::type<double>::nan();
      }

      static double mp_IJoff(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          boundary_conditions = (unsigned int)_mp_arg(5),
          siz = (unsigned int)mp.opcode[6];
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const longT
          off = (longT)(is_relative?img.offset((int)mp.mem[_cimg_mp_slot_x],
                                               (int)mp.mem[_cimg_mp_slot_y],
                                               (int)mp.mem[_cimg_mp_slot_z]) + _mp_arg(4):_mp_arg(4)),
          whd = (longT)img.width()*img.height()*img.depth();
        const T *ptrs;
        if (off>=0 && off<whd) {
          ptrs = &img[off];
          cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
          return cimg::type<double>::nan();
        }
        if (img._data) switch (boundary_conditions) {
          case 3 : { // Mirror
            const longT whd2 = 2*whd, moff = cimg::mod(off,whd2);
            ptrs = &img[moff<whd?moff:whd2 - moff - 1];
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
            return cimg::type<double>::nan();
          }
          case 2 : // Periodic
            ptrs = &img[cimg::mod(off,whd)];
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
            return cimg::type<double>::nan();
          case 1 : // Neumann
            ptrs = off<0?&img[0]:&img[whd - 1];
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
            return cimg::type<double>::nan();
          default : // Dirichlet
            std::memset(ptrd,0,siz*sizeof(double));
            return cimg::type<double>::nan();
          }
        std::memset(ptrd,0,siz*sizeof(double));
        return cimg::type<double>::nan();
      }

      static double mp_IJxyz3(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(7),
          boundary_conditions = (unsigned int)_mp_arg(8),
          siz = (unsigned int)mp.opcode[9];
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4),
          y = is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5),
          z = is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6);
        const ulongT whd = (ulongT)img._width*img._height*img._depth;
        const T *ptrs;
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth();
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              mz = cimg::mod((float)z,(float)d2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXYZ(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXYZ_p((float)x,(float)y,(float)z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXYZ((float)x,(float)y,(float)z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.cubic_atXYZ((float)x,(float)y,(float)z,c,(T)0);
          } break;
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth();
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              mz = cimg::mod((float)z,(float)d2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXYZ(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXYZ_p((float)x,(float)y,(float)z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXYZ((float)x,(float)y,(float)z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.linear_atXYZ((float)x,(float)y,(float)z,c,(T)0);
          } break;
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              mx = cimg::mod((int)x,w2),
              my = cimg::mod((int)y,h2),
              mz = cimg::mod((int)z,d2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 2 : { // Periodic
            const int
              cx = (int)cimg::mod(x,(double)img._width),
              cy = (int)cimg::mod(y,(double)img._height),
              cz = (int)cimg::mod(z,(double)img._depth);
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 1 : { // Neumann
            ptrs = &img._atXYZ((int)x,(int)y,(int)z);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          default : // Dirichlet
            if (img.containsXYZC((int)x,(int)y,(int)z)) {
              ptrs = &img((int)x,(int)y,(int)z);
              cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
            } else std::memset(ptrd,0,siz*sizeof(double));
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_IJxyz2(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(7),
          boundary_conditions = (unsigned int)_mp_arg(8),
          siz = (unsigned int)mp.opcode[9];
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4),
          y = is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5);
        const int
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6));
        const ulongT whd = (ulongT)img._width*img._height*img._depth;
        const T *ptrs;
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              mz = cimg::mod(z,d2),
              cz = mz<img.depth()?mz:d2 - mz - 1;
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXY(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXY_p((float)x,(float)y,z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atXY((float)x,(float)y,z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.cubic_atXY((float)x,(float)y,z,c,(T)0);
          } break;
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              mz = cimg::mod(z,d2),
              cz = mz<img.depth()?mz:d2 - mz - 1;
            const float
              mx = cimg::mod((float)x,(float)w2),
              my = cimg::mod((float)y,(float)h2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXY(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXY_p((float)x,(float)y,z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atXY((float)x,(float)y,z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.linear_atXY((float)x,(float)y,z,c,(T)0);
          } break;
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              mz = cimg::mod(z,d2),
              mx = cimg::mod((int)x,w2),
              my = cimg::mod((int)y,h2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 2 : { // Periodic
            const int
              cx = (int)cimg::mod(x,(double)img._width),
              cy = (int)cimg::mod(y,(double)img._height),
              cz = cimg::mod(z,img.depth());
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 1 : { // Neumann
            ptrs = &img._atXYZ((int)x,(int)y,z);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          default : // Dirichlet
            if (img.containsXYZC((int)x,(int)y,z)) {
              ptrs = &img((int)x,(int)y,z);
              cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
            } else std::memset(ptrd,0,siz*sizeof(double));
          }
        }
        return cimg::type<double>::nan();
      }

      static double mp_IJxyz1(_cimg_math_parser& mp) {
        double *ptrd = &_mp_arg(1) + 1;
        const bool is_relative = (bool)mp.opcode[2];
        const unsigned int
          _ind = (unsigned int)mp.opcode[3],
          ind = _ind==~0U?~0U:(unsigned int)cimg::mod((int)mp.mem[_ind],mp.imglist.width()),
          interpolation = (unsigned int)_mp_arg(7),
          boundary_conditions = (unsigned int)_mp_arg(8),
          siz = (unsigned int)mp.opcode[9];
        const CImg<T> &img = ind==~0U?mp.imgin:mp.imglist[ind];
        const double
          x = is_relative?(mp.mem[_cimg_mp_slot_x] + _mp_arg(4)):_mp_arg(4);
        const int
          y = (int)(is_relative?(mp.mem[_cimg_mp_slot_y] + _mp_arg(5)):_mp_arg(5)),
          z = (int)(is_relative?(mp.mem[_cimg_mp_slot_z] + _mp_arg(6)):_mp_arg(6));
        const ulongT whd = (ulongT)img._width*img._height*img._depth;
        const T *ptrs;
        switch (interpolation) {
        case 2 : // Cubic interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            const float
              mx = cimg::mod((float)x,(float)w2),
              cx = mx<img.width()?mx:w2 - mx - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atX(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atX_p((float)x,y,z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._cubic_atX((float)x,y,z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.cubic_atX((float)x,y,z,c,(T)0);
          } break;
        case 1 : // Linear interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            const float
              mx = cimg::mod((float)x,(float)w2),
              cx = mx<img.width()?mx:w2 - mx - 1;
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atX(cx,cy,cz,c);
          } break;
          case 2 : // Periodic
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atX_p((float)x,y,z,c);
            break;
          case 1 : // Neumann
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img._linear_atX((float)x,y,z,c);
            break;
          default : // Dirichlet
            cimg_for_inC(img,0,siz - 1,c) *(ptrd++) = (double)img.linear_atX((float)x,y,z,c,(T)0);
          } break;
        default : // Nearest neighbor interpolation
          switch (boundary_conditions) {
          case 3 : { // Mirror
            const int
              w2 = 2*img.width(), h2 = 2*img.height(), d2 = 2*img.depth(),
              my = cimg::mod(y,h2),
              mz = cimg::mod(z,d2),
              mx = cimg::mod((int)x,w2),
              cx = mx<img.width()?mx:w2 - mx - 1,
              cy = my<img.height()?my:h2 - my - 1,
              cz = mz<img.depth()?mz:d2 - mz - 1;
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 2 : { // Periodic
            const int
              cx = (int)cimg::mod(x,(double)img._width),
              cy = cimg::mod(y,img.height()),
              cz = cimg::mod(z,img.depth());
            ptrs = &img(cx,cy,cz);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          case 1 : { // Neumann
            ptrs = &img._atXYZ((int)x,y,z);
            cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
          } break;
          default : // Dirichlet
            if (img.containsXYZC((int)x,y,z)) {
              ptrs = &img((int)x,y,z);
              cimg_for_inC(img,0,siz - 1,c) { *(ptrd++) = (double)*ptrs; ptrs+=whd; }
            } else std::memset(ptrd,0,siz*sizeof(double));
          }
        }
        return cimg::type<double>::nan();
      }

#undef _mp_arg

    }; // struct _cimg_math_parser {}

#define _cimg_create_pointwise_functions(name,func,min_size) \
    CImg<T>& name() { \
      if (is_empty()) return *this; \
      cimg_openmp_for(*this,func((typename cimg::superset<T,float>::type)*ptr),min_size,T); \
      return *this; \
    } \
    CImg<Tfloat> get_##name() const { \
      return CImg<Tfloat>(*this,false).name(); \
    }

    //! Compute the square value of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its square value \f$I_{(x,y,z,c)}^2\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
       \par Example
       \code
       const CImg<float> img("reference.jpg");
       (img,img.get_sqr().normalize(0,255)).display();
       \endcode
       \image html ref_sqr.jpg
    **/
    _cimg_create_pointwise_functions(sqr,cimg::sqr,524288)

    //! Compute the square root of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its square root \f$\sqrt{I_{(x,y,z,c)}}\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
       \par Example
       \code
       const CImg<float> img("reference.jpg");
       (img,img.get_sqrt().normalize(0,255)).display();
       \endcode
       \image html ref_sqrt.jpg
    **/
    _cimg_create_pointwise_functions(sqrt,std::sqrt,8192)

    //! Compute the exponential of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its exponential \f$e^{I_{(x,y,z,c)}}\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(exp,std::exp,4096)

    //! Compute the error function of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its error function.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
#if cimg_use_cpp11==1
    _cimg_create_pointwise_functions(erf,std::erf,4096)
#endif

    //! Compute the logarithm of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its logarithm
       \f$\mathrm{log}_{e}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(log,std::log,262144)

    //! Compute the base-2 logarithm of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its base-2 logarithm
       \f$\mathrm{log}_{2}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(log2,cimg::log2,4096)

    //! Compute the base-10 logarithm of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its base-10 logarithm
       \f$\mathrm{log}_{10}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(log10,std::log10,4096)

    //! Compute the absolute value of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its absolute value \f$|I_{(x,y,z,c)}|\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(abs,cimg::abs,524288)

    //! Compute the sign of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its sign
       \f$\mathrm{sign}(I_{(x,y,z,c)})\f$.
       \note
       - The sign is set to:
         - \c 1 if pixel value is strictly positive.
         - \c -1 if pixel value is strictly negative.
         - \c 0 if pixel value is equal to \c 0.
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(sign,cimg::sign,32768)

    //! Compute the cosine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its cosine \f$\cos(I_{(x,y,z,c)})\f$.
       \note
       - Pixel values are regarded as being in \e radians.
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(cos,std::cos,8192)

    //! Compute the sine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its sine \f$\sin(I_{(x,y,z,c)})\f$.
       \note
       - Pixel values are regarded as being in \e radians.
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(sin,std::sin,8192)

    //! Compute the sinc of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its sinc
       \f$\mathrm{sinc}(I_{(x,y,z,c)})\f$.
       \note
       - Pixel values are regarded as being in \e radians.
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(sinc,cimg::sinc,2048)

    //! Compute the tangent of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its tangent \f$\tan(I_{(x,y,z,c)})\f$.
       \note
       - Pixel values are regarded as being in \e radians.
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(tan,std::tan,2048)

    //! Compute the hyperbolic cosine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its hyperbolic cosine
       \f$\mathrm{cosh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(cosh,std::cosh,2048)

    //! Compute the hyperbolic sine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its hyperbolic sine
       \f$\mathrm{sinh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(sinh,std::sinh,2048)

    //! Compute the hyperbolic tangent of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its hyperbolic tangent
       \f$\mathrm{tanh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(tanh,std::tanh,2048)

    //! Compute the arccosine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its arccosine
       \f$\mathrm{acos}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(acos,std::acos,8192)

    //! Compute the arcsine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its arcsine
       \f$\mathrm{asin}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(asin,std::asin,8192)

    //! Compute the arctangent of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its arctangent
       \f$\mathrm{atan}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(atan,std::atan,8192)

    //! Compute the arctangent2 of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its arctangent2
       \f$\mathrm{atan2}(I_{(x,y,z,c)})\f$.
       \param img Image whose pixel values specify the second argument of the \c atan2() function.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
       \par Example
       \code
       const CImg<float>
          img_x(100,100,1,1,"x-w/2",false), // Define an horizontal centered gradient, from '-width/2' to 'width/2'
          img_y(100,100,1,1,"y-h/2",false), // Define a vertical centered gradient, from '-height/2' to 'height/2'
          img_atan2 = img_y.get_atan2(img_x); // Compute atan2(y,x) for each pixel value
       (img_x,img_y,img_atan2).display();
       \endcode
    **/
    template<typename t>
    CImg<T>& atan2(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return atan2(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)std::atan2((double)*ptrd,(double)*(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)std::atan2((double)*ptrd,(double)*(ptrs++));
      }
      return *this;
    }

    //! Compute the arctangent2 of each pixel value \newinstance.
    template<typename t>
    CImg<Tfloat> get_atan2(const CImg<t>& img) const {
      return CImg<Tfloat>(*this,false).atan2(img);
    }

    //! Compute the hyperbolic arccosine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its arccosineh
       \f$\mathrm{acosh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(acosh,cimg::acosh,8192)

    //! Compute the hyperbolic arcsine of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its hyperbolic arcsine
       \f$\mathrm{asinh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(asinh,cimg::asinh,8192)

    //! Compute the hyperbolic arctangent of each pixel value.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its hyperbolic arctangent
       \f$\mathrm{atanh}(I_{(x,y,z,c)})\f$.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
    **/
    _cimg_create_pointwise_functions(atanh,cimg::atanh,8192)

    //! In-place pointwise multiplication.
    /**
       Compute the pointwise multiplication between the image instance and the specified input image \c img.
       \param img Input image, as the second operand of the multiplication.
       \note
       - Similar to operator+=(const CImg<t>&), except that it performs a pointwise multiplication
         instead of an addition.
       - It does \e not perform a \e matrix multiplication. For this purpose, use operator*=(const CImg<t>&) instead.
       \par Example
       \code
       CImg<float>
         img("reference.jpg"),
         shade(img.width,img.height(),1,1,"-(x-w/2)^2-(y-h/2)^2",false);
       shade.normalize(0,1);
       (img,shade,img.get_mul(shade)).display();
       \endcode
    **/
    template<typename t>
    CImg<T>& mul(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return mul(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)(*ptrd * *(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)(*ptrd * *(ptrs++));
      }
      return *this;
    }

    //! In-place pointwise multiplication \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_mul(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).mul(img);
    }

    //! In-place pointwise division.
    /**
       Similar to mul(const CImg<t>&), except that it performs a pointwise division instead of a multiplication.
    **/
    template<typename t>
    CImg<T>& div(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return div(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)(*ptrd / *(ptrs++));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)(*ptrd / *(ptrs++));
      }
      return *this;
    }

    //! In-place pointwise division \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_div(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).div(img);
    }

    //! Raise each pixel value to a specified power.
    /**
       Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by its power \f$I_{(x,y,z,c)}^p\f$.
       \param p Exponent value.
       \note
       - The \inplace of this function statically casts the computed values to the pixel type \c T.
       - The \newinstance returns a \c CImg<float> image, if the pixel type \c T is \e not float-valued.
       \par Example
       \code
       const CImg<float>
         img0("reference.jpg"), // Load reference color image
         img1 = (img0/255).pow(1.8)*=255, // Compute gamma correction, with gamma = 1.8
         img2 = (img0/255).pow(0.5)*=255; // Compute gamma correction, with gamma = 0.5
       (img0,img1,img2).display();
       \endcode
    **/
    CImg<T>& pow(const double p) {
      if (is_empty()) return *this;
      if (p==-4) { cimg_openmp_for(*this,1/(Tfloat)cimg::pow4(*ptr),32768,T); return *this; }
      if (p==-3) { cimg_openmp_for(*this,1/(Tfloat)cimg::pow3(*ptr),32768,T); return *this; }
      if (p==-2) { cimg_openmp_for(*this,1/(Tfloat)cimg::sqr(*ptr),32768,T); return *this; }
      if (p==-1) { cimg_openmp_for(*this,1/(Tfloat)*ptr,32768,T); return *this; }
      if (p==-0.5) { cimg_openmp_for(*this,1/std::sqrt((Tfloat)*ptr),8192,T); return *this; }
      if (p==0) return fill((T)1);
      if (p==0.5) return sqrt();
      if (p==1) return *this;
      if (p==2) return sqr();
      if (p==3) { cimg_openmp_for(*this,cimg::pow3(*ptr),262144,T); return *this; }
      if (p==4) { cimg_openmp_for(*this,cimg::pow4(*ptr),131072,T); return *this; }
      cimg_openmp_for(*this,std::pow((Tfloat)*ptr,(Tfloat)p),1024,T);
      return *this;
    }

    //! Raise each pixel value to a specified power \newinstance.
    CImg<Tfloat> get_pow(const double p) const {
      return CImg<Tfloat>(*this,false).pow(p);
    }

    //! Raise each pixel value to a power, specified from an expression.
    /**
       Similar to operator+=(const char*), except it performs a pointwise exponentiation instead of an addition.
    **/
    CImg<T>& pow(const char *const expression) {
      return pow((+*this)._fill(expression,true,3,(CImgList<T>*)0,"pow",this,(CImg<doubleT>*)0));
    }

    //! Raise each pixel value to a power, specified from an expression \newinstance.
    CImg<Tfloat> get_pow(const char *const expression) const {
      return CImg<Tfloat>(*this,false).pow(expression);
    }

    //! Raise each pixel value to a power, pointwisely specified from another image.
    /**
       Similar to operator+=(const CImg<t>& img), except that it performs an exponentiation instead of an addition.
    **/
    template<typename t>
    CImg<T>& pow(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return pow(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)std::pow((double)*ptrd,(double)(*(ptrs++)));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)std::pow((double)*ptrd,(double)(*(ptrs++)));
      }
      return *this;
    }

    //! Raise each pixel value to a power, pointwisely specified from another image \newinstance.
    template<typename t>
    CImg<Tfloat> get_pow(const CImg<t>& img) const {
      return CImg<Tfloat>(*this,false).pow(img);
    }

    //! Compute the bitwise left rotation of each pixel value.
    /**
       Similar to operator<<=(unsigned int), except that it performs a left rotation instead of a left shift.
    **/
    CImg<T>& rol(const unsigned int n=1) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,cimg::rol(*ptr,n),32768,T);
      return *this;
    }

    //! Compute the bitwise left rotation of each pixel value \newinstance.
    CImg<T> get_rol(const unsigned int n=1) const {
      return (+*this).rol(n);
    }

    //! Compute the bitwise left rotation of each pixel value.
    /**
       Similar to operator<<=(const char*), except that it performs a left rotation instead of a left shift.
    **/
    CImg<T>& rol(const char *const expression) {
      return rol((+*this)._fill(expression,true,3,(CImgList<T>*)0,"rol",this,(CImg<doubleT>*)0));
    }

    //! Compute the bitwise left rotation of each pixel value \newinstance.
    CImg<T> get_rol(const char *const expression) const {
      return (+*this).rol(expression);
    }

    //! Compute the bitwise left rotation of each pixel value.
    /**
       Similar to operator<<=(const CImg<t>&), except that it performs a left rotation instead of a left shift.
    **/
    template<typename t>
    CImg<T>& rol(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return rol(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)cimg::rol(*ptrd,(unsigned int)(*(ptrs++)));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)cimg::rol(*ptrd,(unsigned int)(*(ptrs++)));
      }
      return *this;
    }

    //! Compute the bitwise left rotation of each pixel value \newinstance.
    template<typename t>
    CImg<T> get_rol(const CImg<t>& img) const {
      return (+*this).rol(img);
    }

    //! Compute the bitwise right rotation of each pixel value.
    /**
       Similar to operator>>=(unsigned int), except that it performs a right rotation instead of a right shift.
    **/
    CImg<T>& ror(const unsigned int n=1) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,cimg::ror(*ptr,n),32768,T);
      return *this;
    }

    //! Compute the bitwise right rotation of each pixel value \newinstance.
    CImg<T> get_ror(const unsigned int n=1) const {
      return (+*this).ror(n);
    }

    //! Compute the bitwise right rotation of each pixel value.
    /**
       Similar to operator>>=(const char*), except that it performs a right rotation instead of a right shift.
    **/
    CImg<T>& ror(const char *const expression) {
      return ror((+*this)._fill(expression,true,3,(CImgList<T>*)0,"ror",this,(CImg<doubleT>*)0));
    }

    //! Compute the bitwise right rotation of each pixel value \newinstance.
    CImg<T> get_ror(const char *const expression) const {
      return (+*this).ror(expression);
    }

    //! Compute the bitwise right rotation of each pixel value.
    /**
       Similar to operator>>=(const CImg<t>&), except that it performs a right rotation instead of a right shift.
    **/
    template<typename t>
    CImg<T>& ror(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return ror(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = (T)cimg::ror(*ptrd,(unsigned int)(*(ptrs++)));
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = (T)cimg::ror(*ptrd,(unsigned int)(*(ptrs++)));
      }
      return *this;
    }

    //! Compute the bitwise right rotation of each pixel value \newinstance.
    template<typename t>
    CImg<T> get_ror(const CImg<t>& img) const {
      return (+*this).ror(img);
    }

    //! Softmax operator.
    CImg<T>& softmax(const float temperature=1) {
      return get_softmax(temperature).move_to(*this);
    }

    //! Softmax operator \newinstance.
    CImg<Tfloat> get_softmax(const float temperature=1) const {
      if (is_empty()) return CImg<Tfloat>();
      CImg<Tfloat> res(_width,_height,_depth,_spectrum);
      const T val_max = max();
      Tfloat sum = 0;
      cimg_pragma_openmp(parallel reduction(+:sum) cimg_openmp_if_size(size(),4096)) {
        cimg_pragma_openmp(for)
        cimg_rofoff(*this,off) {
          const Tfloat val = std::exp(((Tfloat)_data[off] - val_max)/temperature);
          res[off] = val;
          sum+=val;
        }
      }
      return res/=sum;
    }

    //! Softmin operator.
    CImg<T>& softmin(const float temperature=1) {
      return get_softmin(temperature).move_to(*this);
    }

    //! Softmin operator \newinstance.
    CImg<Tfloat> get_softmin(const float temperature=1) const {
      if (is_empty()) return CImg<Tfloat>();
      CImg<Tfloat> res(_width,_height,_depth,_spectrum);
      const T val_min = min();
      Tfloat sum = 0;
      cimg_pragma_openmp(parallel reduction(+:sum) cimg_openmp_if_size(size(),4096)) {
        cimg_pragma_openmp(for)
        cimg_rofoff(*this,off) {
          const Tfloat val = std::exp((-(Tfloat)_data[off] + val_min)/temperature);
          res[off] = val;
          sum+=val;
        }
      }
      return res/=sum;
    }

    //! Pointwise min operator between instance image and a value.
    /**
       \param value Value used as the reference argument of the min operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$ \mathrm{min}(I_{(x,y,z,c)},\mathrm{val}) \f$.
     **/
    CImg<T>& min(const T& value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,std::min(*ptr,value),65536,T);
      return *this;
    }

    //! Pointwise min operator between instance image and a value \newinstance.
    CImg<T> get_min(const T& value) const {
      return (+*this).min(value);
    }

    //! Pointwise min operator between two images.
    /**
       \param img Image used as the reference argument of the min operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{min}(I_{(x,y,z,c)},\mathrm{img}_{(x,y,z,c)})\f$.
     **/
    template<typename t>
    CImg<T>& min(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return min(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = std::min((T)*(ptrs++),*ptrd);
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = std::min((T)*(ptrs++),*ptrd);
      }
      return *this;
    }

    //! Pointwise min operator between two images \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_min(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).min(img);
    }

    //! Pointwise min operator between an image and an expression.
    /**
       \param expression Math formula as a C-string.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{min}(I_{(x,y,z,c)},\mathrm{expr}_{(x,y,z,c)})\f$.
    **/
    CImg<T>& min(const char *const expression) {
      return min((+*this)._fill(expression,true,3,(CImgList<T>*)0,"min",this,(CImg<doubleT>*)0));
    }

    //! Pointwise min operator between an image and an expression \newinstance.
    CImg<Tfloat> get_min(const char *const expression) const {
      return CImg<Tfloat>(*this,false).min(expression);
    }

    //! Pointwise max operator between instance image and a value.
    /**
       \param value Value used as the reference argument of the max operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{max}(I_{(x,y,z,c)},\mathrm{val})\f$.
     **/
    CImg<T>& max(const T& value) {
      if (is_empty()) return *this;
      cimg_openmp_for(*this,std::max(*ptr,value),65536,T);
      return *this;
    }

    //! Pointwise max operator between instance image and a value \newinstance.
    CImg<T> get_max(const T& value) const {
      return (+*this).max(value);
    }

    //! Pointwise max operator between two images.
    /**
       \param img Image used as the reference argument of the max operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{max}(I_{(x,y,z,c)},\mathrm{img}_{(x,y,z,c)})\f$.
     **/
    template<typename t>
    CImg<T>& max(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return max(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = std::max((T)*(ptrs++),*ptrd);
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = std::max((T)*(ptrs++),*ptrd);
      }
      return *this;
    }

    //! Pointwise max operator between two images \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_max(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).max(img);
    }

    //! Pointwise max operator between an image and an expression.
    /**
       \param expression Math formula as a C-string.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{max}(I_{(x,y,z,c)},\mathrm{expr}_{(x,y,z,c)})\f$.
    **/
    CImg<T>& max(const char *const expression) {
      return max((+*this)._fill(expression,true,3,(CImgList<T>*)0,"max",this,(CImg<doubleT>*)0));
    }

    //! Pointwise max operator between an image and an expression \newinstance.
    CImg<Tfloat> get_max(const char *const expression) const {
      return CImg<Tfloat>(*this,false).max(expression);
    }

    //! Pointwise minabs operator between instance image and a value.
    /**
       \param value Value used as the reference argument of the minabs operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{minabs}(I_{(x,y,z,c)},\mathrm{val})\f$.
     **/
    CImg<T>& minabs(const T& value) {
      if (is_empty()) return *this;
      const T absvalue = cimg::abs(value);
      cimg_openmp_for(*this,cimg::minabs(*ptr,value,absvalue),65536,T);
      return *this;
    }

    //! Pointwise minabs operator between instance image and a value \newinstance.
    CImg<T> get_minabs(const T& value) const {
      return (+*this).minabs(value);
    }

    //! Pointwise minabs operator between two images.
    /**
       \param img Image used as the reference argument of the minabs operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{minabs}(I_{(x,y,z,c)},\mathrm{img}_{(x,y,z,c)})\f$.
     **/
    template<typename t>
    CImg<T>& minabs(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return minabs(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = cimg::minabs((T)*(ptrs++),*ptrd);
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = cimg::minabs((T)*(ptrs++),*ptrd);
      }
      return *this;
    }

    //! Pointwise minabs operator between two images \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_minabs(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).minabs(img);
    }

    //! Pointwise minabs operator between an image and an expression.
    /**
       \param expression Math formula as a C-string.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{minabs}(I_{(x,y,z,c)},\mathrm{expr}_{(x,y,z,c)})\f$.
    **/
    CImg<T>& minabs(const char *const expression) {
      return minabs((+*this)._fill(expression,true,3,(CImgList<T>*)0,"minabs",this,(CImg<doubleT>*)0));
    }

    //! Pointwise minabs operator between an image and an expression \newinstance.
    CImg<Tfloat> get_minabs(const char *const expression) const {
      return CImg<Tfloat>(*this,false).minabs(expression);
    }

    //! Pointwise maxabs operator between instance image and a value.
    /**
       \param value Value used as the reference argument of the maxabs operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{maxabs}(I_{(x,y,z,c)},\mathrm{val})\f$.
     **/
    CImg<T>& maxabs(const T& value) {
      if (is_empty()) return *this;
      const T absvalue = cimg::abs(value);
      cimg_openmp_for(*this,cimg::maxabs(*ptr,value,absvalue),65536,T);
      return *this;
    }

    //! Pointwise maxabs operator between instance image and a value \newinstance.
    CImg<T> get_maxabs(const T& value) const {
      return (+*this).maxabs(value);
    }

    //! Pointwise maxabs operator between two images.
    /**
       \param img Image used as the reference argument of the maxabs operator.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{maxabs}(I_{(x,y,z,c)},\mathrm{img}_{(x,y,z,c)})\f$.
     **/
    template<typename t>
    CImg<T>& maxabs(const CImg<t>& img) {
      const ulongT siz = size(), isiz = img.size();
      if (siz && isiz) {
        if (is_overlapped(img)) return maxabs(+img);
        T *ptrd = _data, *const ptre = _data + siz;
        if (siz>isiz) for (ulongT n = siz/isiz; n; --n)
          for (const t *ptrs = img._data, *ptrs_end = ptrs + isiz; ptrs<ptrs_end; ++ptrd)
            *ptrd = cimg::maxabs((T)*(ptrs++),*ptrd);
        for (const t *ptrs = img._data; ptrd<ptre; ++ptrd) *ptrd = cimg::maxabs((T)*(ptrs++),*ptrd);
      }
      return *this;
    }

    //! Pointwise maxabs operator between two images \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_maxabs(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this,false).maxabs(img);
    }

    //! Pointwise maxabs operator between an image and an expression.
    /**
       \param expression Math formula as a C-string.
       \note Replace each pixel value \f$I_{(x,y,z,c)}\f$ of the image instance by
       \f$\mathrm{maxabs}(I_{(x,y,z,c)},\mathrm{expr}_{(x,y,z,c)})\f$.
    **/
    CImg<T>& maxabs(const char *const expression) {
      return maxabs((+*this)._fill(expression,true,3,(CImgList<T>*)0,"maxabs",this,(CImg<doubleT>*)0));
    }

    //! Pointwise maxabs operator between an image and an expression \newinstance.
    CImg<Tfloat> get_maxabs(const char *const expression) const {
      return CImg<Tfloat>(*this,false).maxabs(expression);
    }

    //! Return a reference to the minimum pixel value.
    /**
     **/
    T& min() {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "min(): Empty instance.",
                                    cimg_instance);
      T *ptr_min = _data;
      T min_value = *ptr_min;
      cimg_for(*this,ptrs,T) if (*ptrs<min_value) min_value = *(ptr_min=ptrs);
      return *ptr_min;
    }

    //! Return a reference to the minimum pixel value \const.
    const T& min() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "min(): Empty instance.",
                                    cimg_instance);
      const T *ptr_min = _data;
      T min_value = *ptr_min;
      cimg_for(*this,ptrs,T) if (*ptrs<min_value) min_value = *(ptr_min=ptrs);
      return *ptr_min;
    }

    //! Return a reference to the minimum pixel value in absolute value.
    /**
     **/
    T& minabs() {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "minabs(): Empty instance.",
                                    cimg_instance);
      T *ptr_minabs = _data;
      T minabs_value = *ptr_minabs;
      cimg_for(*this,ptrs,T) {
        const T ma = cimg::abs(*ptrs);
        if (ma<minabs_value) { minabs_value = ma; ptr_minabs = ptrs; }
      }
      return *ptr_minabs;
    }

    //! Return a reference to the minimum pixel value in absolute value \const.
    const T& minabs() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "minabs(): Empty instance.",
                                    cimg_instance);
      const T *ptr_minabs = _data;
      T minabs_value = *ptr_minabs;
      cimg_for(*this,ptrs,T) {
        const T ma = cimg::abs(*ptrs);
        if (ma<minabs_value) { minabs_value = ma; ptr_minabs = ptrs; }
      }
      return *ptr_minabs;
    }

    //! Return a reference to the maximum pixel value.
    /**
     **/
    T& max() {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "max(): Empty instance.",
                                    cimg_instance);
      T *ptr_max = _data;
      T max_value = *ptr_max;
      cimg_for(*this,ptrs,T) if (*ptrs>max_value) max_value = *(ptr_max=ptrs);
      return *ptr_max;
    }

    //! Return a reference to the maximum pixel value \const.
    const T& max() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "max(): Empty instance.",
                                    cimg_instance);
      const T *ptr_max = _data;
      T max_value = *ptr_max;
      cimg_for(*this,ptrs,T) if (*ptrs>max_value) max_value = *(ptr_max=ptrs);
      return *ptr_max;
    }

    //! Return a reference to the maximum pixel value in absolute value.
    /**
     **/
    T& maxabs() {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "maxabs(): Empty instance.",
                                    cimg_instance);
      T *ptr_maxabs = _data;
      T maxabs_value = *ptr_maxabs;
      cimg_for(*this,ptrs,T) {
        const T ma = cimg::abs(*ptrs);
        if (ma>maxabs_value) { maxabs_value = ma; ptr_maxabs = ptrs; }
      }
      return *ptr_maxabs;
    }

    //! Return a reference to the maximum pixel value in absolute value \const.
    const T& maxabs() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "maxabs(): Empty instance.",
                                    cimg_instance);
      const T *ptr_maxabs = _data;
      T maxabs_value = *ptr_maxabs;
      cimg_for(*this,ptrs,T) {
        const T ma = cimg::abs(*ptrs);
        if (ma>maxabs_value) { maxabs_value = ma; ptr_maxabs = ptrs; }
      }
      return *ptr_maxabs;
    }

    //! Return a reference to the minimum pixel value as well as the maximum pixel value.
    /**
       \param[out] max_val Maximum pixel value.
    **/
    template<typename t>
    T& min_max(t& max_val) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "min_max(): Empty instance.",
                                    cimg_instance);
      const T *ptr_min, *ptr_max;
      _min_max(ptr_min,ptr_max);
      max_val = (t)*ptr_max;
      return (T&)*ptr_min;
    }

    void _min_max(const T* &ptr_min, const T* &ptr_max) const {
      T val_min = *_data, val_max = val_min;
      ptr_min = ptr_max = _data;
      if (cimg_use_openmp && size()>(1LU<<24)*cimg_openmp_sizefactor) { // Parallel version
#if cimg_use_openmp
        cimg_pragma_openmp(parallel) {
          T l_val_min = *_data, l_val_max = l_val_min;
          const T *l_ptr_min = _data, *l_ptr_max = l_ptr_min;
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) {
            const T *const ptr = _data + off;
            const T val = *ptr;
            if (val<l_val_min) { l_val_min = val; l_ptr_min = ptr; }
            if (val>l_val_max) { l_val_max = val; l_ptr_max = ptr; }
          }
          cimg_pragma_openmp(critical(_min_max)) {
            if (l_val_min<val_min || (l_val_min==val_min && l_ptr_min<ptr_min)) {
              val_min = l_val_min; ptr_min = l_ptr_min;
            }
            if (l_val_max>val_max || (l_val_max==val_max && l_ptr_max<ptr_max)) {
              val_max = l_val_max; ptr_max = l_ptr_max;
            }
          }
        }
#endif
      } else { // Single-threaded version.
        cimg_for(*this,ptrs,T) {
          const T val = *ptrs;
          if (val<val_min) { val_min = val; ptr_min = ptrs; }
          if (val>val_max) { val_max = val; ptr_max = ptrs; }
        }
      }
    }

    //! Return a reference to the minimum pixel value as well as the maximum pixel value \const.
    template<typename t>
    const T& min_max(t& max_val) const {
      return ((CImg<T>*)this)->min_max(max_val);
    }

    //! Return a reference to the maximum pixel value as well as the minimum pixel value.
    /**
       \param[out] min_val Minimum pixel value.
    **/
    template<typename t>
    T& max_min(t& min_val) {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "max_min(): Empty instance.",
                                    cimg_instance);
      const T *ptr_min, *ptr_max;
      _min_max(ptr_min,ptr_max);
      min_val = (t)*ptr_min;
      return (T&)*ptr_max;
    }

    //! Return a reference to the maximum pixel value as well as the minimum pixel value \const.
    template<typename t>
    const T& max_min(t& min_val) const {
      return ((CImg<T>*)this)->max_min(min_val);
    }

    //! Return the kth smallest pixel value.
    /**
       \param k Rank of the smallest element searched.
    **/
    T kth_smallest(const ulongT k) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "kth_smallest(): Empty instance.",
                                    cimg_instance);
      if (k>=size()) return max();
      CImg<T> arr(*this,false);
      ulongT l = 0, ir = size() - 1;
      for ( ; ; ) {
        if (ir<=l + 1) {
          if (ir==l + 1 && arr[ir]<arr[l]) cimg::swap(arr[l],arr[ir]);
          return arr[k];
        } else {
          const ulongT mid = (l + ir)>>1;
          cimg::swap(arr[mid],arr[l + 1]);
          if (arr[l]>arr[ir]) cimg::swap(arr[l],arr[ir]);
          if (arr[l + 1]>arr[ir]) cimg::swap(arr[l + 1],arr[ir]);
          if (arr[l]>arr[l + 1]) cimg::swap(arr[l],arr[l + 1]);
          ulongT i = l + 1, j = ir;
          const T pivot = arr[l + 1];
          for ( ; ; ) {
            do ++i; while (arr[i]<pivot);
            do --j; while (arr[j]>pivot);
            if (j<i) break;
            cimg::swap(arr[i],arr[j]);
          }
          arr[l + 1] = arr[j];
          arr[j] = pivot;
          if (j>=k) ir = j - 1;
          if (j<=k) l = i;
        }
      }
    }

    //! Return the median pixel value.
    /**
     **/
    T median() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "median(): Empty instance.",
                                    cimg_instance);
      const ulongT s = size();
      switch (s) {
      case 1 : return _data[0];
      case 2 : return cimg::median(_data[0],_data[1]);
      case 3 : return cimg::median(_data[0],_data[1],_data[2]);
      case 5 : return cimg::median(_data[0],_data[1],_data[2],_data[3],_data[4]);
      case 7 : return cimg::median(_data[0],_data[1],_data[2],_data[3],_data[4],_data[5],_data[6]);
      case 9 : return cimg::median(_data[0],_data[1],_data[2],_data[3],_data[4],_data[5],_data[6],_data[7],_data[8]);
      case 13 : return cimg::median(_data[0],_data[1],_data[2],_data[3],_data[4],_data[5],_data[6],_data[7],_data[8],
                                    _data[9],_data[10],_data[11],_data[12]);
      }
      const ulongT ind = s>>1;
      if (s%2) return kth_smallest(ind);
      const CImg<T> sorted = get_sort();
      return (T)((sorted[ind] + sorted[ind - 1])/2);
    }

    //! Return greatest common diviser of all image values.
    T gcd() const {
      if (is_empty()) return 0;
      const ulongT siz = size();
      longT res = (longT)*_data;
      for (ulongT k = 1; k<siz; ++k) res = cimg::gcd(res,(longT)_data[k]);
      return res;
    }

    //! Return least common multiplier of all image values.
    T lcm() const {
      if (is_empty()) return 0;
      const ulongT siz = size();
      longT res = (longT)*_data;
      for (ulongT k = 1; k<siz; ++k) res = cimg::lcm(res,(longT)_data[k]);
      return res;
    }

    //! Return the product of all the pixel values.
    /**
     **/
    double product() const {
      if (is_empty()) return 0;
      double res = 1;
      cimg_for(*this,ptrs,T) res*=(double)*ptrs;
      return res;
    }

    //! Return the sum of all the pixel values.
    /**
     **/
    double sum() const {
      double res = 0;
      cimg_for(*this,ptrs,T) res+=(double)*ptrs;
      return res;
    }

    //! Return the average pixel value.
    /**
     **/
    double mean() const {
      double res = 0;
      cimg_for(*this,ptrs,T) res+=(double)*ptrs;
      return res/size();
    }

    //! Return the variance of the pixel values.
    /**
       \param variance_method Method used to estimate the variance. Can be:
       - \c 0: Second moment, computed as
       \f$1/N \sum\limits_{k=1}^{N} (x_k - \bar x)^2 =
       1/N \left( \sum\limits_{k=1}^N x_k^2 - \left( \sum\limits_{k=1}^N x_k \right)^2 / N \right)\f$
       with \f$ \bar x = 1/N \sum\limits_{k=1}^N x_k \f$.
       - \c 1: Best unbiased estimator, computed as \f$\frac{1}{N - 1} \sum\limits_{k=1}^{N} (x_k - \bar x)^2 \f$.
       - \c 2: Least median of squares.
       - \c 3: Least trimmed of squares.
    **/
    double variance(const unsigned int variance_method=0) const {
      double foo;
      return variance_mean(variance_method,foo);
    }

    //! Return the variance as well as the average of the pixel values.
    /**
       \param variance_method Method used to estimate the variance (see variance(const unsigned int) const).
       \param[out] mean Average pixel value.
    **/
    template<typename t>
    double variance_mean(const unsigned int variance_method, t& mean) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "variance_mean(): Empty instance.",
                                    cimg_instance);
      double var = 0, sum = 0;
      const ulongT siz = size();
      if (!siz) { mean = (t)0; return 0; }
      if (siz==1) { mean = (t)*_data; return 0; }
      switch (variance_method) {
      case 0 : case 1 : { // Population/unbiased (using Welford method)
        double m = 0, S2 = 0;
        ulongT n = 0;
        cimg_for(*this,ptrs,T) {
          const double val = (double)*ptrs, delta = val - m;
          m+=delta/++n;
          const double delta2 = val - m;
          S2+=delta*delta2;
        }
        mean = (t)m;
        var = S2/(siz - variance_method);
      } break;
      case 2 : { // Least Median of Squares (MAD)
        CImg<Tfloat> buf(*this,false);
        buf.sort();
        const ulongT siz2 = siz>>1;
        const double med_i = (double)buf[siz2];
        cimg_for(buf,ptrs,Tfloat) {
          const double val = (double)*ptrs; *ptrs = (Tfloat)cimg::abs(val - med_i); sum+=val;
        }
        buf.sort();
        const double sig = (double)(1.4828*buf[siz2]);
        var = sig*sig;
      } break;
      default : { // Least trimmed of Squares
        CImg<Tfloat> buf(*this,false);
        const ulongT siz2 = siz>>1;
        cimg_for(buf,ptrs,Tfloat) {
          const double val = (double)*ptrs; (*ptrs)=(Tfloat)((*ptrs)*val); sum+=val;
        }
        buf.sort();
        double a = 0;
        const Tfloat *ptrs = buf._data;
        for (ulongT j = 0; j<siz2; ++j) a+=(double)*(ptrs++);
        const double sig = (double)(2.6477*std::sqrt(a/siz2));
        var = sig*sig;
      }
      }
      if (variance_method>1) mean = (t)(sum/siz);
      return std::max(var,0.);
    }

    //! Return estimated variance of the noise.
    /**
       \param variance_method Method used to compute the variance (see variance(const unsigned int) const).
       \note Because of structures such as edges in images it is
       recommended to use an unbiased variance estimation. The variance of the
       noise is estimated by computing the variance of the Laplacian \f$(\Delta
       I)^2 \f$ scaled by a factor \f$c\f$ insuring \f$ c E[(\Delta I)^2]=
       \sigma^2\f$ where \f$\sigma\f$ is the noise variance.
    **/
    double variance_noise(const unsigned int variance_method=2) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "variance_noise(): Empty instance.",
                                    cimg_instance);

      const ulongT siz = size();
      if (siz<2 || !_data) return 0;
      if (variance_method>1) { // Compute a scaled version of the Laplacian
        CImg<Tdouble> tmp(*this,false);
        if (_depth==1) {
          const double cste = 1./std::sqrt(20.); // Depends on how the Laplacian is computed
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*262144 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            CImg_3x3(I,T);
            cimg_for3x3(*this,x,y,0,c,I,T) {
              tmp(x,y,c) = cste*((double)Inc + (double)Ipc + (double)Icn +
                                 (double)Icp - 4*(double)Icc);
            }
          }
        } else {
          const double cste = 1./std::sqrt(42.); // Depends on how the Laplacian is computed
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*262144 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            CImg_3x3x3(I,T);
            cimg_for3x3x3(*this,x,y,z,c,I,T) {
              tmp(x,y,z,c) = cste*((double)Incc + (double)Ipcc + (double)Icnc + (double)Icpc +
                                   (double)Iccn + (double)Iccp - 6*(double)Iccc);
            }
          }
        }
        return tmp.variance(variance_method);
      }

      // Version that doesn't need intermediate images.
      double m = 0, S2 = 0;
      ulongT n = 0;
      if (_depth==1) {
        const double cste = 1./std::sqrt(20.);
        CImg_3x3(I,T);
        cimg_forC(*this,c) cimg_for3x3(*this,x,y,0,c,I,T) {
          const double
            val = cste*((double)Inc + (double)Ipc + (double)Icn + (double)Icp - 4*(double)Icc),
            delta = val - m;
          m+=delta/++n;
          const double delta2 = val - m;
          S2+=delta*delta2;
        }
      } else {
        const double cste = 1./std::sqrt(42.);
        CImg_3x3x3(I,T);
        cimg_forC(*this,c) cimg_for3x3x3(*this,x,y,z,c,I,T) {
          const double
            val = cste*((double)Incc + (double)Ipcc + (double)Icnc + (double)Icpc +
                        (double)Iccn + (double)Iccp - 6*(double)Iccc),
            delta = val - m;
          m+=delta/++n;
          const double delta2 = val - m;
          S2+=delta*delta2;
        }
      }
      return std::max(S2/(n - variance_method),0.);
    }

    //! Compute the MSE (Mean-Squared Error) between two images.
    /**
       \param img Image used as the second argument of the MSE operator.
    **/
    template<typename t>
    double MSE(const CImg<t>& img) const {
      if (img.size()!=size())
        throw CImgArgumentException(_cimg_instance
                                    "MSE(): Instance and specified image (%u,%u,%u,%u,%p) have different dimensions.",
                                    cimg_instance,
                                    img._width,img._height,img._depth,img._spectrum,img._data);
      double vMSE = 0;
      const t* ptr2 = img._data;
      cimg_for(*this,ptr1,T) {
        const double diff = (double)*ptr1 - (double)*(ptr2++);
        vMSE+=diff*diff;
      }
      const ulongT siz = img.size();
      if (siz) vMSE/=siz;
      return vMSE;
    }

    //! Compute the PSNR (Peak Signal-to-Noise Ratio) between two images.
    /**
       \param img Image used as the second argument of the PSNR operator.
       \param max_value Maximum theoretical value of the signal.
     **/
    template<typename t>
    double PSNR(const CImg<t>& img, const double max_value=255) const {
      const double vMSE = (double)std::sqrt(MSE(img));
      return (vMSE!=0)?(double)(20*std::log10(max_value/vMSE)):(double)(cimg::type<double>::max());
    }

    //! Evaluate math formula.
    /**
       \param expression Math formula, as a C-string.
       \param x Value of the predefined variable \c x.
       \param y Value of the predefined variable \c y.
       \param z Value of the predefined variable \c z.
       \param c Value of the predefined variable \c c.
       \param list_images A list of images attached to the specified math formula.
    **/
    double eval(const char *const expression,
                const double x=0, const double y=0, const double z=0, const double c=0,
                CImgList<T> *const list_images=0) {
      return _eval(this,expression,x,y,z,c,list_images);
    }

    //! Evaluate math formula \const.
    double eval(const char *const expression,
                const double x=0, const double y=0, const double z=0, const double c=0,
                CImgList<T> *const list_images=0) const {
      return _eval(0,expression,x,y,z,c,list_images);
    }

    // Fast function to pre-evaluate common expressions.
    // (return 'true' in case of success, and set value of 'res').
    template<typename t>
    bool __eval(const char *const expression, t &res) const {

#define __eval_op(op) if (__eval_get(++ptr,val2) && !*ptr) { res = (t)(op); return true; } else return false;

      double val1, val2;
      if (!expression || !*expression || *expression==';' || *expression=='[') return false;
      if (!expression[1]) switch (*expression) {
        case 'w' : res = (t)_width; return true;
        case 'h' : res = (t)_height; return true;
        case 'd' : res = (t)_depth; return true;
        case 's' : res = (t)_spectrum; return true;
        case 'r' : res = (t)_is_shared; return true;
        default : if (*expression>='0' && *expression<='9') { res = (t)(*expression - '0'); return true; }
        }
      if (*expression=='w' && expression[1]=='h') {
        if (!expression[2]) { res = (t)(_width*_height); return true; }
        if (expression[2]=='d') {
          if (!expression[3]) { res = (t)(_width*_height*_depth); return true; }
          if (expression[3]=='s' && !expression[4]) { res = (t)(_width*_height*_depth*_spectrum); return true; }
        }
        if (expression[2]=='s' && !expression[3]) { res = (t)(_width*_height*_spectrum); return true; }
      }
      const char *ptr = expression;
      while (*ptr && cimg::is_blank(*ptr)) ++ptr;
      if (*ptr=='\'' && *(++ptr)) { // Detect 'stringA' op 'stringB' (op='==' or '!=')
        const char *ptr2 = std::strchr(ptr,'\'');
        if (ptr2) {
          const char *ptr3 = ptr2 + 1;
          while (*ptr3 && cimg::is_blank(*ptr3)) ++ptr3;
          const char *ptr4 = ptr3;
          if ((*ptr3=='!' || *ptr3=='=') && *(++ptr4)=='=') {
            ++ptr4;
            while (*ptr4 && cimg::is_blank(*ptr4)) ++ptr4;
            if (*ptr4=='\'' && *(++ptr4)) {
              const char *const ptr5 = std::strchr(ptr4,'\'');
              if (ptr5) {
                const char *ptr6 = ptr5 + 1;
                while (*ptr6 && cimg::is_blank(*ptr6)) ++ptr6;
                if (!*ptr6) {
                  CImg<charT> str1(ptr,ptr2 - ptr,1,1,1,true), str2(ptr4,ptr5 - ptr4,1,1,1,true);
                  if (*ptr3=='!') res = (t)!(str1==str2); else res = (t)(str1==str2);
                  return true;
                }
              }
            }
          }
        }
        return false;
      }
      if (__eval_get(ptr,val1)) { // Detect 'value1' op 'value2'
        switch (*ptr) {
        case 0 : res = (t)val1; return true;
        case '+' : __eval_op(val1 + val2);
        case '-' : __eval_op(val1 - val2);
        case '*' : __eval_op(val1 * val2);
        case '/' : __eval_op(val1 / val2);
        case '%' : __eval_op(cimg::mod(val1,val2));
        case '&' : if (ptr[1]=='&') { ++ptr; __eval_op(val1 && val2); } else { __eval_op((long)val1 & (long)val2); }
        case '|' : if (ptr[1]=='|') { ++ptr; __eval_op(val1 || val2); } else { __eval_op((long)val1 | (long)val2); }
        case '>' : if (ptr[1]=='=') { ++ptr; __eval_op(val1>=val2); } else { __eval_op(val1>val2); }
        case '<' : if (ptr[1]=='=') { ++ptr; __eval_op(val1<=val2); } else { __eval_op(val1<val2); }
        case ';' : __eval_op(val2);
        case '^' : __eval_op(std::pow(val1,val2));
        case '=' : if (*++ptr=='=') { __eval_op(val1==val2); } else return false;
        case '!' : if (*++ptr=='=') { __eval_op(val1!=val2); } else return false;
        }
      }
      return false;
    }

    // Return 'true' is a single 'value' or '!value' has been successfully read ('value' being a double or { w,h,d,s }).
    bool __eval_get(const char* &ptr, double &value) const {
      int n = 0;
      while (*ptr && cimg::is_blank(*ptr)) ++ptr;

      bool is_not = false; // Detect preceding '!' operator
      if (*ptr=='!') { is_not = true; ++ptr; while (*ptr && cimg::is_blank(*ptr)) ++ptr; }

      if ((*ptr=='w' || *ptr=='h' || *ptr=='d' || *ptr=='s' || *ptr=='r') || cimg_sscanf(ptr,"%lf %n",&value,&n)==1) {
        if (!n) {
          switch (*ptr) {
          case 'w': value = (double)_width; break;
          case 'h': value = (double)_height; break;
          case 'd': value = (double)_depth; break;
          case 's': value = (double)_spectrum; break;
          case 'r': value = (double)_is_shared; break;
          }
          ++ptr; while (*ptr && cimg::is_blank(*ptr)) ++ptr;
        } else ptr+=n;
        if (is_not) value = (double)!value;
        return true;
      }
      return false;
    }

    double _eval(CImg<T> *const img_output, const char *const expression,
                 const double x, const double y, const double z, const double c,
                 CImgList<T> *const list_images) const {
      if (!expression || !*expression) return 0;
      double _val = 0;
      if (__eval(expression,_val)) return _val;
      _cimg_math_parser mp(expression + (*expression=='>' || *expression=='<' || *expression=='+' ||
                                         *expression=='*' || *expression==':'),"eval",
                           *this,img_output,list_images,false);
      mp.begin_t();
      const double val = mp(x,y,z,c);
      mp.end_t();
      mp.end();
      return val;
    }

    //! Evaluate math formula.
    /**
       \param[out] output Contains values of output vector returned by the evaluated expression
         (or is empty if the returned type is scalar).
       \param expression Math formula, as a C-string.
       \param x Value of the predefined variable \c x.
       \param y Value of the predefined variable \c y.
       \param z Value of the predefined variable \c z.
       \param c Value of the predefined variable \c c.
       \param list_images A list of input images attached to the specified math formula.
    **/
    template<typename t>
    void eval(CImg<t> &output, const char *const expression,
              const double x=0, const double y=0, const double z=0, const double c=0,
              CImgList<T> *const list_images=0) {
      _eval(output,this,expression,x,y,z,c,list_images);
    }

    //! Evaluate math formula \const.
    template<typename t>
    void eval(CImg<t>& output, const char *const expression,
              const double x=0, const double y=0, const double z=0, const double c=0,
              CImgList<T> *const list_images=0) const {
      _eval(output,0,expression,x,y,z,c,list_images);
    }

    template<typename t>
    void _eval(CImg<t>& output, CImg<T> *const img_output, const char *const expression,
               const double x, const double y, const double z, const double c,
               CImgList<T> *const list_images) const {
      if (!expression || !*expression) { output.assign(1); *output = 0; return; }
      double _val = 0;
      if (__eval(expression,_val)) { output.assign(1); *output = _val; return; }
      _cimg_math_parser mp(expression + (*expression=='>' || *expression=='<' || *expression=='+' ||
                                         *expression=='*' || *expression==':'),"eval",
                           *this,img_output,list_images,false);
      output.assign(1,std::max(1U,mp.result_dim));
      mp.begin_t();
      mp(x,y,z,c,output._data);
      mp.end_t();
      mp.end();
    }

    //! Evaluate math formula on a set of variables.
    /**
       \param expression Math formula, as a C-string.
       \param xyzc Set of values (x,y,z,c) used for the evaluation.
       \param list_images A list of input images attached to the specified math formula.
    **/
    template<typename t>
    CImg<doubleT> eval(const char *const expression, const CImg<t>& xyzc,
                       CImgList<T> *const list_images=0) {
      return _eval(this,expression,xyzc,list_images);
    }

    //! Evaluate math formula on a set of variables \const.
    template<typename t>
    CImg<doubleT> eval(const char *const expression, const CImg<t>& xyzc,
                       CImgList<T> *const list_images=0) const {
      return _eval(0,expression,xyzc,list_images);
    }

    template<typename t>
    CImg<doubleT> _eval(CImg<T> *const output, const char *const expression, const CImg<t>& xyzc,
                        CImgList<T> *const list_images=0) const {
      CImg<doubleT> res(1,xyzc.size()/4);
      if (!expression || !*expression) return res.fill(0);
      _cimg_math_parser mp(expression,"eval",*this,output,list_images,false);

#if cimg_use_openmp!=0
      const int num_threads = (int)std::min(res.size(),(ulongT)omp_get_max_threads());
      cimg_pragma_openmp(parallel if (num_threads>0 && res._height>=512) num_threads(num_threads)) {
        _cimg_math_parser
          *const _mp = omp_get_thread_num()?new _cimg_math_parser(mp):&mp,
          &lmp = *_mp;
        cimg_pragma_openmp(barrier)
        lmp.begin_t();
        cimg_pragma_openmp(for)
        for (int i = 0; i<res.height(); ++i) {
          const unsigned int i4 = 4*i;
          const double
            x = (double)xyzc[i4], y = (double)xyzc[i4 + 1],
            z = (double)xyzc[i4 + 2], c = (double)xyzc[i4 + 3];
          res[i] = lmp(x,y,z,c);
        }
        lmp.end_t();
        cimg_pragma_openmp(barrier) cimg_pragma_openmp(critical) { lmp.merge(mp); }
        if (&lmp!=&mp) delete &lmp;
      }
#else
      mp.begin_t();
      const t *ps = xyzc._data;
      cimg_for(res,pd,double) {
        const double x = (double)*(ps++), y = (double)*(ps++), z = (double)*(ps++), c = (double)*(ps++);
        *pd = mp(x,y,z,c);
      }
      mp.end_t();
#endif
      mp.end();
      return res;
    }

    //! Compute statistics vector from the pixel values.
    /**
       \param variance_method Method used to compute the variance (see variance(const unsigned int) const).
       \return Statistics vector as
         <tt>[ min, max, mean, variance, xmin, ymin, zmin, cmin, xmax, ymax, zmax, cmax, sum, product, L2-norm ]</tt>.
    **/
    CImg<Tdouble> get_stats(const unsigned int variance_method=0) const {
      if (is_empty()) return CImg<doubleT>();
      const ulongT siz = size();
      const longT off_end = (longT)siz;
      double avg = 0, S = 0, S2 = 0, P = 1, N = 0;
      longT offm = 0, offM = 0, n = 0;
      T m = *_data, M = m;
      cimg_pragma_openmp(parallel reduction(+:S,S2) reduction(*:P)
                         cimg_openmp_if(variance_method>1 && siz>=(cimg_openmp_sizefactor)*131072)) {
        longT loffm = 0, loffM = 0;
        T lm = *_data, lM = lm;
        cimg_pragma_openmp(for)
        for (longT off = 0; off<off_end; ++off) {
          const T val = _data[off];
          const double _val = (double)val;
          if (val<lm) { lm = val; loffm = off; }
          if (val>lM) { lM = val; loffM = off; }
          S+=_val;
          P*=_val;
          N+=_val*_val;
          if (variance_method<1) {
           const double delta = _val - avg;
           avg+=delta/++n;
           const double delta2 = _val - avg;
           S2+=delta*delta2;
          }
        }
        cimg_pragma_openmp(critical(get_stats)) {
          if (lm<m || (lm==m && loffm<offm)) { m = lm; offm = loffm; }
          if (lM>M || (lM==M && loffM<offM)) { M = lM; offM = loffM; }
        }
      }

      const double
        mean_value = S/siz,
        variance_value = siz<2?0:std::max(variance_method<2?S2/(siz - variance_method):variance(variance_method),0.);
      int
        xm = 0, ym = 0, zm = 0, cm = 0,
        xM = 0, yM = 0, zM = 0, cM = 0;
      contains(_data[offm],xm,ym,zm,cm);
      contains(_data[offM],xM,yM,zM,cM);
      return CImg<Tdouble>(1,15).fill((double)m,(double)M,mean_value,variance_value,
                                      (double)xm,(double)ym,(double)zm,(double)cm,
                                      (double)xM,(double)yM,(double)zM,(double)cM,
                                      S,P,std::sqrt(N));
    }

    //! Compute statistics vector from the pixel values \inplace.
    CImg<T>& stats(const unsigned int variance_method=0) {
      return get_stats(variance_method).move_to(*this);
    }

    //@}
    //-------------------------------------
    //
    //! \name Vector / Matrix Operations
    //@{
    //-------------------------------------

    //! Compute norm of the image, viewed as a matrix.
    /**
       \param magnitude_type Can be:
       - \c 0: L0-norm
       - \c 1: L1-norm
       - \c 2: L2-norm
       - \c p>2 : Lp-norm
       - \c ~0U: Linf-norm
    **/
    double magnitude(const float magnitude_type=2) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "magnitude(): Empty instance.",
                                    cimg_instance);
      const ulongT siz = size();
      double res = 0;
      if (magnitude_type==2) { // L2
        cimg_pragma_openmp(parallel for reduction(+:res) cimg_openmp_if_size(size(),8192))
        for (longT off = 0; off<(longT)siz; ++off) res+=(double)cimg::sqr(_data[off]);
        res = (double)std::sqrt(res);
      } else if (magnitude_type==1) { // L1
        cimg_pragma_openmp(parallel for reduction(+:res) cimg_openmp_if_size(size(),8192))
        for (longT off = 0; off<(longT)siz; ++off) res+=(double)cimg::abs(_data[off]);
      } else if (!magnitude_type) { // L0
        cimg_pragma_openmp(parallel for reduction(+:res) cimg_openmp_if_size(size(),8192))
        for (longT off = 0; off<(longT)siz; ++off) res+=(double)(_data[off]?1:0);
      } else if (cimg::type<float>::is_inf(magnitude_type)) { // L-inf
        cimg_for(*this,ptrs,T) { const double val = (double)cimg::abs(*ptrs); if (val>res) res = val; }
      } else { // L-p
        cimg_pragma_openmp(parallel for reduction(+:res) cimg_openmp_if_size(size(),8192))
        for (longT off = 0; off<(longT)siz; ++off)
          res+=(double)std::pow((double)cimg::abs(_data[off]),(double)magnitude_type);
        res = (double)std::pow(res,1.0/magnitude_type);
      }
      return res;
    }

    //! Compute the trace of the image, viewed as a matrix.
    /**
     **/
    double trace() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "trace(): Empty instance.",
                                    cimg_instance);
      double res = 0;
      cimg_forX(*this,k) res+=(double)(*this)(k,k);
      return res;
    }

    //! Compute the determinant of the image, viewed as a matrix.
    /**
     **/
    double det() const {
      if (is_empty() || _width!=_height || _depth!=1 || _spectrum!=1)
        throw CImgInstanceException(_cimg_instance
                                    "det(): Instance is not a square matrix.",
                                    cimg_instance);
      switch (_width) {
      case 1 : return (double)((*this)(0,0));
      case 2 : return (double)((*this)(0,0))*(double)((*this)(1,1)) - (double)((*this)(0,1))*(double)((*this)(1,0));
      case 3 : {
        const double
          a = (double)_data[0], d = (double)_data[1], g = (double)_data[2],
          b = (double)_data[3], e = (double)_data[4], h = (double)_data[5],
          c = (double)_data[6], f = (double)_data[7], i = (double)_data[8];
        return i*a*e - a*h*f - i*b*d + b*g*f + c*d*h - c*g*e;
      }
      default : {
        CImg<doubleT> Q, R;
        QR(Q,R,false);
        double res = 1;
        cimg_forX(R,i) res*=R(i,i);
        cimg_forX(R,i) if (R(i,i)<0) res = -res;
        return res;
      }
      }
    }

    //! Compute the dot product between instance and argument, viewed as matrices.
    /**
       \param img Image used as a second argument of the dot product.
    **/
    template<typename t>
    double dot(const CImg<t>& img) const {
      const ulongT nb = std::min(size(),img.size());
      double res = 0;
      cimg_pragma_openmp(parallel for reduction(+:res) cimg_openmp_if_size(nb,8192))
      for (longT off = 0; off<(longT)nb; ++off) res+=(double)_data[off]*(double)img[off];
      return res;
    }

    //! Get vector-valued pixel located at specified position.
    /**
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
    **/
    CImg<T> get_vector_at(const unsigned int x, const unsigned int y=0, const unsigned int z=0) const {
      CImg<T> res;
      if (res._height!=_spectrum) res.assign(1,_spectrum);
      const ulongT whd = (ulongT)_width*_height*_depth;
      const T *ptrs = data(x,y,z);
      T *ptrd = res._data;
      cimg_forC(*this,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
      return res;
    }

    //! Get (square) matrix-valued pixel located at specified position.
    /**
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \note - The spectrum() of the image must be a square.
     **/
    CImg<T> get_matrix_at(const unsigned int x=0, const unsigned int y=0, const unsigned int z=0) const {
      const int n = (int)cimg::round(std::sqrt((double)_spectrum));
      const T *ptrs = data(x,y,z,0);
      const ulongT whd = (ulongT)_width*_height*_depth;
      CImg<T> res(n,n);
      T *ptrd = res._data;
      cimg_forC(*this,c) { *(ptrd++) = *ptrs; ptrs+=whd; }
      return res;
    }

    //! Get tensor-valued pixel located at specified position.
    /**
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
    **/
    CImg<T> get_tensor_at(const unsigned int x, const unsigned int y=0, const unsigned int z=0) const {
      const T *ptrs = data(x,y,z,0);
      const ulongT whd = (ulongT)_width*_height*_depth;
      if (_spectrum==6)
        return tensor(*ptrs,*(ptrs + whd),*(ptrs + 2*whd),*(ptrs + 3*whd),*(ptrs + 4*whd),*(ptrs + 5*whd));
      if (_spectrum==3)
        return tensor(*ptrs,*(ptrs + whd),*(ptrs + 2*whd));
      return tensor(*ptrs);
    }

    //! Set vector-valued pixel at specified position.
    /**
       \param vec Vector to put on the instance image.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
    **/
    template<typename t>
    CImg<T>& set_vector_at(const CImg<t>& vec, const unsigned int x, const unsigned int y=0, const unsigned int z=0) {
      if (x<_width && y<_height && z<_depth) {
        const t *ptrs = vec._data;
        const ulongT whd = (ulongT)_width*_height*_depth;
        T *ptrd = data(x,y,z);
        for (unsigned int k = std::min((unsigned int)vec.size(),_spectrum); k; --k) {
          *ptrd = (T)*(ptrs++); ptrd+=whd;
        }
      }
      return *this;
    }

    //! Set (square) matrix-valued pixel at specified position.
    /**
       \param mat Matrix to put on the instance image.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
    **/
    template<typename t>
    CImg<T>& set_matrix_at(const CImg<t>& mat, const unsigned int x=0, const unsigned int y=0, const unsigned int z=0) {
      return set_vector_at(mat,x,y,z);
    }

    //! Set tensor-valued pixel at specified position.
    /**
       \param ten Tensor to put on the instance image.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
    **/
    template<typename t>
    CImg<T>& set_tensor_at(const CImg<t>& ten, const unsigned int x=0, const unsigned int y=0, const unsigned int z=0) {
      T *ptrd = data(x,y,z,0);
      const ulongT siz = (ulongT)_width*_height*_depth;
      if (ten._height==2) {
        *ptrd = (T)ten[0]; ptrd+=siz;
        *ptrd = (T)ten[1]; ptrd+=siz;
        *ptrd = (T)ten[3];
      }
      else {
        *ptrd = (T)ten[0]; ptrd+=siz;
        *ptrd = (T)ten[1]; ptrd+=siz;
        *ptrd = (T)ten[2]; ptrd+=siz;
        *ptrd = (T)ten[4]; ptrd+=siz;
        *ptrd = (T)ten[5]; ptrd+=siz;
        *ptrd = (T)ten[8];
      }
      return *this;
    }

    //! Resize image to become a diagonal matrix.
    /**
       \note Transform the image as a diagonal matrix so that each of its initial value becomes a diagonal coefficient.
    **/
    CImg<T>& diagonal() {
      return get_diagonal().move_to(*this);
    }

    //! Resize image to become a diagonal matrix \newinstance.
    CImg<T> get_diagonal() const {
      if (is_empty()) return *this;
      const unsigned int siz = (unsigned int)size();
      CImg<T> res(siz,siz,1,1,0);
      cimg_foroff(*this,off) res((unsigned int)off,(unsigned int)off) = (*this)[off];
      return res;
    }

    //! Replace the image by an identity matrix.
    /**
       \note If the instance image is not square, it is resized to a square matrix using its maximum
       dimension as a reference.
    **/
    CImg<T>& identity_matrix() {
      return identity_matrix(std::max(_width,_height)).move_to(*this);
    }

    //! Replace the image by an identity matrix \newinstance.
    CImg<T> get_identity_matrix() const {
      return identity_matrix(std::max(_width,_height));
    }

    //! Fill image with a linear sequence of values.
    /**
       \param a0 Starting value of the sequence.
       \param a1 Ending value of the sequence.
    **/
    CImg<T>& sequence(const T& a0, const T& a1) {
      if (is_empty()) return *this;
      const ulongT siz = size() - 1;
      T* ptr = _data;
      if (siz) {
        const double delta = (double)a1 - (double)a0;
        cimg_foroff(*this,l) *(ptr++) = (T)(a0 + delta*l/siz);
      } else *ptr = a0;
      return *this;
    }

    //! Fill image with a linear sequence of values \newinstance.
    CImg<T> get_sequence(const T& a0, const T& a1) const {
      return (+*this).sequence(a0,a1);
    }

    //! Transpose the image, viewed as a matrix.
    /**
       \note Equivalent to \code permute_axes("yxzc"); \endcode.
    **/
    CImg<T>& transpose() {
      if (_width==1) { _width = _height; _height = 1; return *this; }
      if (_height==1) { _height = _width; _width = 1; return *this; }
      if (_width==_height) {
        cimg_forYZC(*this,y,z,c) for (int x = y; x<width(); ++x) cimg::swap((*this)(x,y,z,c),(*this)(y,x,z,c));
        return *this;
      }
      return get_transpose().move_to(*this);
    }

    //! Transpose the image, viewed as a matrix \newinstance.
    CImg<T> get_transpose() const {
      return get_permute_axes("yxzc");
    }

    //! Compute the cross product between two \c 1x3 images, viewed as 3D vectors.
    /**
       \param img Image used as the second argument of the cross product.
       \note The first argument of the cross product is \c *this.
     **/
    template<typename t>
    CImg<T>& cross(const CImg<t>& img) {
      if (_width!=1 || _height<3 || img._width!=1 || img._height<3)
        throw CImgInstanceException(_cimg_instance
                                    "cross(): Instance and/or specified image (%u,%u,%u,%u,%p) are not 3D vectors.",
                                    cimg_instance,
                                    img._width,img._height,img._depth,img._spectrum,img._data);

      const T x = (*this)[0], y = (*this)[1], z = (*this)[2];
      (*this)[0] = (T)(y*img[2] - z*img[1]);
      (*this)[1] = (T)(z*img[0] - x*img[2]);
      (*this)[2] = (T)(x*img[1] - y*img[0]);
      return *this;
    }

    //! Compute the cross product between two \c 1x3 images, viewed as 3D vectors \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_cross(const CImg<t>& img) const {
      return CImg<_cimg_Tt>(*this).cross(img);
    }

    //! Invert the instance matrix.
    /**
       If the instance matrix is not square, the Moore-Penrose pseudo-inverse is computed instead.
    **/
    CImg<T>& invert() {
      return get_invert().move_to(*this);
    }

    //! Invert the instance matrix.
    CImg<Tfloat> get_invert() const {
      if (_depth!=1 || _spectrum!=1)
        throw CImgArgumentException(_cimg_instance
              "invert(): Instance is not a matrix.",
                                    cimg_instance);
      if (_height==_width) // Square matrix
        return CImg<T>::identity_matrix(_height).get_solve(*this);
      if (_height>_width) { // Tall matrix: (A^t.A)^-1.A^t
        const CImg<T> At = get_transpose();
        return At.get_solve(At*(*this));
      }
      // Wide matrix: ((A.A^t)^-1.A)^t
      return get_solve((*this)*get_transpose()).transpose();
    }

    //! Solve a (possibly over- or under-determined) linear system using QR decomposition.
    /**
       \brief Solve the matrix equation \f$ A\,X = B \f$, where the current instance \c *this represents \f$ B \f$,
       and the argument \c A is the system matrix. This function supports both over-determined and
       under-determined systems by internally performing a QR decomposition with column pivoting,
       which improves numerical stability and correctly handles rank-deficient matrices.

       - If \f$ A \f$ has more rows than columns (\f$ m \ge n \f$), the system is square or over-determined,
         and the least-squares solution minimizing \f$ \|A\,X - B\|_2 \f$ is computed.
       - If \f$ A \f$ has more columns than rows (\f$ m < n \f$), the system is under-determined.
         The minimum-norm solution is computed using QR decomposition with column pivoting
         of the transposed system.

       The computation is performed in double precision for numerical stability.
    **/
    template<typename t>
    CImg<T>& solve(const CImg<t>& A) {
      return get_solve(A).move_to(*this);
    }

    //! Solve a (possibly over- or under-determined) linear system using QR decomposition \newinstance.
    template<typename t>
    CImg<_cimg_Ttfloat> get_solve(const CImg<t>& A) const {
      if (_depth!=1 || _spectrum!=1 || _height!=A._height || A._depth!=1 || A._spectrum!=1)
        throw CImgArgumentException(_cimg_instance
                                    "solve(): Instance and specified matrix (%u,%u,%u,%u,%p) have "
                                    "incompatible dimensions.",
                                    cimg_instance,
                                    A._width,A._height,A._depth,A._spectrum,A._data);
      typedef _cimg_Ttfloat Ttfloat;
      if (is_empty()) return CImg<Ttfloat>();
      if (A._height!=A._width) {
        // Non-square systems: use Moore-Penrose pseudo-inverse to lower memory usage in QR decomposition.
        const CImg<T> At = A.get_transpose();
        const CImg<Ttfloat> invA = A._height>A._width?At.get_solve(At*A):A.get_solve(A*At).transpose();
        return invA*(*this);
      }

      const int m = A.height(), n = A.width(), p = width();
      CImg<doubleT> Q, R;
      CImg<uintT> perm;

      // m>=n: Over-determined or square system.
      if (m>=n) {
        A.QR(Q,R,true,true,&perm); // Reduced QR decomposition with column pivoting

        // Compute y = Q^T * b
        const CImg<doubleT> y = Q.get_transpose()*(*this);

        // Detect numerical rank via diagonal of R.
        const double pivtol = 1e-15*std::abs(R(0,0));
        int rank = 0;
        while (rank<n && std::abs(R(rank,rank))>pivtol) ++rank;

        // Solve R(0:rank,0:rank) * x_perm(0:rank) = y(0:rank) by back substitution.
        CImg<doubleT> x(p,n,1,1,0);
        cimg_forX(x,k) {
          for (int i = rank - 1; i>=0; --i) {
            double sum = y(k,i);
            for (int j = i + 1; j<rank; ++j) sum-=R(j,i)*x(k,j);
            x(k,i) = sum/R(i,i);
          }
        }

        // Apply inverse permutation: x_unperm[perm[i]] = x_perm[i].
        CImg<doubleT> xout(p,n,1,1,0);
        cimg_forY(xout,i) cimg_forX(xout,k) xout(k,perm[i]) = x(k,i);
        return xout;
      }

      // m<n: Under-determined system.
      // Solve via QR with pivoting of A^T: A^T * P = Q * R, so A * P = R^T * Q^T.
      // Minimum-norm solution: x = P * R^{-T} * Q^T * b (zero-padded for rank-deficient cases).
      A.get_transpose().QR(Q,R,true,true,&perm);

      // Detect numerical rank.
      const double pivtol = 1e-15*std::abs(R(0,0));
      int rank = 0;
      while (rank<m && std::abs(R(rank,rank))>pivtol) ++rank;

      // Solve R^T * z = b by forward substitution, restricted to detected rank.
      CImg<doubleT> z(p,rank,1,1,0);
      cimg_forX(*this,k) {
        for (int i = 0; i<rank; ++i) {
          double sum = (*this)(k,i);
          for (int j = 0; j<i; ++j) sum-=R(i,j)*z(k,j);
          z(k,i) = sum/R(i,i);
        }
      }

      // Compute x_perm = Q * z (zero-padded to size m if rank < m).
      CImg<doubleT> Qz(p,m,1,1,0);
      cimg_forX(Qz,k) {
        for (int i = 0; i<m; ++i)
          for (int j = 0; j<rank; ++j)
            Qz(k,i)+=Q(j,i)*z(k,j);
      }

      // Apply inverse permutation: xout[perm[i]] = Qz[i].
      CImg<doubleT> xout(p,n,1,1,0);
      cimg_forY(Qz,i) cimg_forX(Qz,k) xout(k,perm[i]) = Qz(k,i);
      return xout;
    }

    //! Solve a tridiagonal system of linear equations.
    /**
       \param A Coefficients of the tridiagonal system.
       A is a tridiagonal matrix A = [ b0,c0,0,...; a1,b1,c1,0,... ; ... ; ...,0,aN,bN ],
       stored as a 3 columns matrix
       \note Solve AX=B where \c B=*this, using the Thomas algorithm.
    **/
    template<typename t>
    CImg<T>& solve_tridiagonal(const CImg<t>& A) {
      const unsigned int siz = (unsigned int)size();
      if (A._width!=3 || A._height!=siz)
        throw CImgArgumentException(_cimg_instance
                                    "solve_tridiagonal(): Instance and tridiagonal matrix "
                                    "(%u,%u,%u,%u,%p) have incompatible dimensions.",
                                    cimg_instance,
                                    A._width,A._height,A._depth,A._spectrum,A._data);
      typedef _cimg_Ttfloat Ttfloat;
      const Ttfloat eps = 1e-4f;
      CImg<Ttfloat> B = A.get_column(1), V(*this,false);
      for (int i = 1; i<(int)siz; ++i) {
        const Ttfloat m = A(0,i)/(B[i - 1]?B[i - 1]:eps);
        B[i] -= m*A(2,i - 1);
        V[i] -= m*V[i - 1];
      }
      (*this)[siz - 1] = (T)(V[siz - 1]/(B[siz - 1]?B[siz - 1]:eps));
      for (int i = (int)siz - 2; i>=0; --i) (*this)[i] = (T)((V[i] - A(2,i)*(*this)[i + 1])/(B[i]?B[i]:eps));
      return *this;
    }

    //! Solve a tridiagonal system of linear equations \newinstance.
    template<typename t>
    CImg<_cimg_Ttfloat> get_solve_tridiagonal(const CImg<t>& A) const {
      return CImg<_cimg_Ttfloat>(*this,false).solve_tridiagonal(A);
    }

    //! Compute eigenvalues and eigenvectors of the instance image, viewed as a matrix.
    /**
       \param[out] val Vector of the estimated eigenvalues, in decreasing order.
       \param[out] vec Matrix of the estimated eigenvectors, sorted by columns.
    **/
    template<typename t>
    const CImg<T>& eigen(CImg<t>& val, CImg<t> &vec) const {
      if (is_empty()) { val.assign(); vec.assign(); }
      else {
        if (_width!=_height || _depth>1 || _spectrum>1)
          throw CImgInstanceException(_cimg_instance
                                      "eigen(): Instance is not a square matrix.",
                                      cimg_instance);

        if (val.size()<(ulongT)_width) val.assign(1,_width);
        if (vec.size()<(ulongT)_width*_width) vec.assign(_width,_width);
        switch (_width) {
        case 1 : { val[0] = (t)(*this)[0]; vec[0] = (t)1; } break;
        case 2 : {
          const double a = (*this)[0], b = (*this)[1], c = (*this)[2], d = (*this)[3], e = a + d;
          double f = e*e - 4*(a*d - b*c);
          if (f<0) cimg::warn(_cimg_instance
                              "eigen(): Complex eigenvalues found.",
                              cimg_instance);
          f = std::sqrt(f);
          const double
            l1 = 0.5*(e - f),
            l2 = 0.5*(e + f),
            b2 = b*b,
            norm1 = std::sqrt(cimg::sqr(l2 - a) + b2),
            norm2 = std::sqrt(cimg::sqr(l1 - a) + b2);
          val[0] = (t)l2;
          val[1] = (t)l1;
          if (norm1>0) { vec(0,0) = (t)(b/norm1); vec(0,1) = (t)((l2 - a)/norm1); } else { vec(0,0) = 1; vec(0,1) = 0; }
          if (norm2>0) { vec(1,0) = (t)(b/norm2); vec(1,1) = (t)((l1 - a)/norm2); } else { vec(1,0) = 1; vec(1,1) = 0; }
        } break;
        default :
          throw CImgInstanceException(_cimg_instance
                                      "eigen(): Eigenvalues computation of general matrices is limited "
                                      "to 2x2 matrices.",
                                      cimg_instance);
        }
      }
      return *this;
    }

    //! Compute eigenvalues and eigenvectors of the instance image, viewed as a matrix.
    /**
       \return A list of two images <tt>[val; vec]</tt>, whose meaning is similar as in eigen(CImg<t>&,CImg<t>&) const.
    **/
    CImgList<Tfloat> get_eigen() const {
      CImgList<Tfloat> res(2);
      eigen(res[0],res[1]);
      return res;
    }

    //! Compute eigenvalues and eigenvectors of the instance image, viewed as a symmetric matrix.
    /**
       \param[out] val Vector of the estimated eigenvalues, in decreasing order.
       \param[out] vec Matrix of the estimated eigenvectors, sorted by columns.
    **/
    template<typename t>
    const CImg<T>& symmetric_eigen(CImg<t>& val, CImg<t>& vec) const {
      if (is_empty()) { val.assign(); vec.assign(); return *this; }
      if (_width!=_height || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "eigen(): Instance is not a square matrix.",
                                    cimg_instance);
      val.assign(1,_width);
      vec.assign(_width,_width);

      if (_width==1) { val[0] = cimg::abs((*this)[0]); vec[0] = 1; return *this; }
      if (_width==2) {
        const double
          a = (*this)[0], b = (*this)[1], c = (*this)[2], d = (*this)[3],
          e = a + d, f = std::sqrt(std::max(e*e - 4*(a*d - b*c),0.0)),
          l1 = 0.5*(e - f), l2 = 0.5*(e + f),
          n = std::sqrt(cimg::sqr(l2 - a) + b*b);
        val[0] = (t)l2;
        val[1] = (t)l1;
        if (n>0) { vec[0] = (t)(b/n); vec[2] = (t)((l2 - a)/n); } else { vec[0] = 1; vec[2] = 0; }
        vec[1] = -vec[2];
        vec[3] = vec[0];
        return *this;
      }
      CImg<t> V(_width,_width);
      Tfloat M = 0, m = (Tfloat)min_max(M), maxabs = cimg::max((Tfloat)1,cimg::abs(m),cimg::abs(M));
      (CImg<Tfloat>(*this,false)/=maxabs).SVD(vec,val,V,false);
      if (maxabs!=1) val*=maxabs;

      // Retrieve signed eigenvalues (compute X^t.A.X, which is more robust than using sign(U_k.V_k)).
      cimg_forY(val,p) {
        const CImg<Tfloat> u = vec.get_column(p);
        val[p] = u.dot((*this)*u);
      }

      // Sort eigenvalues in decreasing order
      CImg<intT> permutations;
      CImg<t> tmp(_width);
      val.sort(permutations,false);
      cimg_forY(vec,k) {
        cimg_forY(permutations,y) tmp(y) = vec(permutations(y),k);
        std::memcpy(vec.data(0,k),tmp._data,sizeof(t)*_width);
      }
      return *this;
    }

    //! Compute eigenvalues and eigenvectors of the instance image, viewed as a symmetric matrix.
    /**
       \return A list of two images <tt>[val; vec]</tt>, whose meaning are similar as in
         symmetric_eigen(CImg<t>&,CImg<t>&) const.
    **/
    CImgList<Tfloat> get_symmetric_eigen() const {
      CImgList<Tfloat> res(2);
      symmetric_eigen(res[0],res[1]);
      return res;
    }

    //! Sort pixel values and get sorting permutations.
    /**
       \param[out] permutations Permutation map used for the sorting.
       \param is_increasing Indicates whether pixel values are sorted in an increasing (\c true) or
         decreasing (\c false) way.
    **/
    template<typename t>
    CImg<T>& sort(CImg<t>& permutations, const bool is_increasing=true) {
      permutations.assign(_width,_height,_depth,_spectrum);
      if (is_empty()) return *this;
      cimg_foroff(permutations,off) permutations[off] = (t)off;
      return _quicksort(0,size() - 1,permutations,is_increasing,true);
    }

    //! Sort pixel values and get sorting permutations \newinstance.
    template<typename t>
    CImg<T> get_sort(CImg<t>& permutations, const bool is_increasing=true) const {
      return (+*this).sort(permutations,is_increasing);
    }

    //! Sort pixel values.
    /**
       \param is_increasing Indicates whether pixel values are sorted in an increasing (\c true) or
         decreasing (\c false) way.
       \param axis Indicates whether the value sorting must be done along a specific axis. Can be:
       - \c 0: All pixel values are sorted, independently on their initial position.
       - \c 'x': Image columns are sorted, according to the first value in each column.
       - \c 'y': Image rows are sorted, according to the first value in each row.
       - \c 'z': Image slices are sorted, according to the first value in each slice.
       - \c 'c': Image channels are sorted, according to the first value in each channel.
    **/
    CImg<T>& sort(const bool is_increasing=true, const char axis=0) {
      if (is_empty()) return *this;
      CImg<uintT> perm;
      switch (cimg::lowercase(axis)) {
      case 0 :
        _quicksort(0,size() - 1,perm,is_increasing,false);
        break;
      case 'x' : {
        perm.assign(_width);
        get_crop(0,0,0,0,_width - 1,0,0,0).sort(perm,is_increasing);
        CImg<T> img(*this,false);
        cimg_forXYZC(*this,x,y,z,c) (*this)(x,y,z,c) = img(perm[x],y,z,c);
      } break;
      case 'y' : {
        perm.assign(_height);
        get_crop(0,0,0,0,0,_height - 1,0,0).sort(perm,is_increasing);
        CImg<T> img(*this,false);
        cimg_forXYZC(*this,x,y,z,c) (*this)(x,y,z,c) = img(x,perm[y],z,c);
      } break;
      case 'z' : {
        perm.assign(_depth);
        get_crop(0,0,0,0,0,0,_depth - 1,0).sort(perm,is_increasing);
        CImg<T> img(*this,false);
        cimg_forXYZC(*this,x,y,z,c) (*this)(x,y,z,c) = img(x,y,perm[z],c);
      } break;
      case 'c' : {
        perm.assign(_spectrum);
        get_crop(0,0,0,0,0,0,0,_spectrum - 1).sort(perm,is_increasing);
        CImg<T> img(*this,false);
        cimg_forXYZC(*this,x,y,z,c) (*this)(x,y,z,c) = img(x,y,z,perm[c]);
      } break;
      default :
        throw CImgArgumentException(_cimg_instance
                                    "sort(): Invalid specified axis '%c' "
                                    "(should be { x | y | z | c }).",
                                    cimg_instance,axis);
      }
      return *this;
    }

    //! Sort pixel values \newinstance.
    CImg<T> get_sort(const bool is_increasing=true, const char axis=0) const {
      return (+*this).sort(is_increasing,axis);
    }

    template<typename t>
    CImg<T>& _quicksort(const long indm, const long indM, CImg<t>& permutations,
                        const bool is_increasing, const bool is_permutations) {
      if (indm<indM) {
        const long mid = (indm + indM)/2;
        if (is_increasing) {
          if ((*this)[indm]>(*this)[mid]) {
            cimg::swap((*this)[indm],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indm],permutations[mid]);
          }
          if ((*this)[mid]>(*this)[indM]) {
            cimg::swap((*this)[indM],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indM],permutations[mid]);
          }
          if ((*this)[indm]>(*this)[mid]) {
            cimg::swap((*this)[indm],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indm],permutations[mid]);
          }
        } else {
          if ((*this)[indm]<(*this)[mid]) {
            cimg::swap((*this)[indm],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indm],permutations[mid]);
          }
          if ((*this)[mid]<(*this)[indM]) {
            cimg::swap((*this)[indM],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indM],permutations[mid]);
          }
          if ((*this)[indm]<(*this)[mid]) {
            cimg::swap((*this)[indm],(*this)[mid]);
            if (is_permutations) cimg::swap(permutations[indm],permutations[mid]);
          }
        }
        if (indM - indm>=3) {
          const T pivot = (*this)[mid];
          long i = indm, j = indM;
          if (is_increasing) {
            do {
              while ((*this)[i]<pivot) ++i;
              while ((*this)[j]>pivot) --j;
              if (i<=j) {
                if (is_permutations) cimg::swap(permutations[i],permutations[j]);
                cimg::swap((*this)[i++],(*this)[j--]);
              }
            } while (i<=j);
          } else {
            do {
              while ((*this)[i]>pivot) ++i;
              while ((*this)[j]<pivot) --j;
              if (i<=j) {
                if (is_permutations) cimg::swap(permutations[i],permutations[j]);
                cimg::swap((*this)[i++],(*this)[j--]);
              }
            } while (i<=j);
          }
          if (indm<j) _quicksort(indm,j,permutations,is_increasing,is_permutations);
          if (i<indM) _quicksort(i,indM,permutations,is_increasing,is_permutations);
        }
      }
      return *this;
    }

    //! Compute the SVD of the instance image, viewed as a general matrix.
    /**
       Compute the SVD decomposition \c *this=U*S*V' where \c U and \c V are orthogonal matrices
       and \c S is a diagonal matrix. \c V' denotes the matrix transpose of \c V.
       \param[out] U First matrix of the SVD product.
       \param[out] S Coefficients of the second (diagonal) matrix of the SVD product.
         These coefficients are stored as a vector.
       \param[out] V Third matrix of the SVD product.
       \param sorting Indicates whether the diagonal coefficients are sorted (in decreasing order).
       \param max_iteration Maximum number of iterations considered for the algorithm convergence.
       \param lambda Epsilon used for the algorithm convergence.
       \note The instance matrix can be computed from \c U,\c S and \c V by
       \code
       const CImg<> A; // Input matrix (assumed to contain some values)
       CImg<> U,S,V;
       A.SVD(U,S,V)
       \endcode
    **/
    template<typename t>
    const CImg<T>& SVD(CImg<t>& U, CImg<t>& S, CImg<t>& V, const bool sorting=true,
                       const unsigned int max_iteration=40, const float lambda=0) const {
      typedef _cimg_Ttfloat Ttfloat;
      const Ttfloat eps = (Ttfloat)1e-8f;
      if (is_empty()) { U.assign(); S.assign(); V.assign(); }
      else if (_depth!=1 || _spectrum!=1)
        throw CImgInstanceException(_cimg_instance
                                    "SVD(): Instance has invalid dimensions (depth or channels different from 1).",
                                    cimg_instance);
      else {
        U = *this;
        if (lambda!=0) {
          const unsigned int delta = std::min(U._width,U._height);
          for (unsigned int i = 0; i<delta; ++i) U(i,i) = (t)(U(i,i) + lambda);
        }
        if (S.size()<_width) S.assign(1,_width);
        if (V._width<_width || V._height<_height) V.assign(_width,_width);
        CImg<t> rv1(_width);
        Ttfloat anorm = 0, c, f, g = 0, h, s, scale = 0;
        int l = 0;

        cimg_forX(U,i) {
          l = i + 1;
          rv1[i] = scale*g;
          g = s = scale = 0;
          if (i<height()) {
            for (int k = i; k<height(); ++k) scale+=cimg::abs(U(i,k));
            if (scale) {
              for (int k = i; k<height(); ++k) {
                U(i,k)/=scale;
                s+=U(i,k)*U(i,k);
              }
              f = U(i,i);
              g = (Ttfloat)((f>=0?-1:1)*std::sqrt(s));
              h = f*g - s;
              U(i,i) = f - g;
              for (int j = l; j<width(); ++j) {
                s = 0;
                for (int k = i; k<height(); ++k) s+=U(i,k)*U(j,k);
                f = s/h;
                for (int k = i; k<height(); ++k) U(j,k)+=f*U(i,k);
              }
              for (int k = i; k<height(); ++k) U(i,k)*=scale;
            }
          }
          S[i] = scale*g;

          g = s = scale = 0;
          if (i<height() && i!=width() - 1) {
            for (int k = l; k<width(); ++k) scale+=cimg::abs(U(k,i));
            if (scale) {
              for (int k = l; k<width(); ++k) {
                U(k,i)/=scale;
                s+=U(k,i)*U(k,i);
              }
              f = U(l,i);
              g = (Ttfloat)((f>=0?-1:1)*std::sqrt(s));
              h = f*g - s;
              U(l,i) = f - g;
              for (int k = l; k<width(); ++k) rv1[k] = U(k,i)/h;
              for (int j = l; j<height(); ++j) {
                s = 0;
                for (int k = l; k<width(); ++k) s+=U(k,j)*U(k,i);
                for (int k = l; k<width(); ++k) U(k,j)+=s*rv1[k];
              }
              for (int k = l; k<width(); ++k) U(k,i)*=scale;
            }
          }
          anorm = (Ttfloat)std::max((float)anorm,(float)(cimg::abs(S[i]) + cimg::abs(rv1[i])));
        }

        for (int i = width() - 1; i>=0; --i) {
          if (i<width() - 1) {
            if (g) {
              for (int j = l; j<width(); ++j) V(i,j) =(U(j,i)/U(l,i))/g;
              for (int j = l; j<width(); ++j) {
                s = 0;
                for (int k = l; k<width(); ++k) s+=U(k,i)*V(j,k);
                for (int k = l; k<width(); ++k) V(j,k)+=s*V(i,k);
              }
            }
            for (int j = l; j<width(); ++j) V(j,i) = V(i,j) = (t)0.;
          }
          V(i,i) = (t)1;
          g = rv1[i];
          l = i;
        }

        for (int i = std::min(width(),height()) - 1; i>=0; --i) {
          l = i + 1;
          g = S[i];
          for (int j = l; j<width(); ++j) U(j,i) = 0;
          if (g) {
            g = 1/g;
            for (int j = l; j<width(); ++j) {
              s = 0;
              for (int k = l; k<height(); ++k) s+=U(i,k)*U(j,k);
              f = (s/U(i,i))*g;
              for (int k = i; k<height(); ++k) U(j,k)+=f*U(i,k);
            }
            for (int j = i; j<height(); ++j) U(i,j)*= g;
          } else for (int j = i; j<height(); ++j) U(i,j) = 0;
          ++U(i,i);
        }

        for (int k = width() - 1; k>=0; --k) {
          int nm = 0;
          for (unsigned int its = 0; its<max_iteration; ++its) {
            bool flag = true;
            for (l = k; l>=1; --l) {
              nm = l - 1;
              if (l==0 || cimg::abs(rv1[l])<=eps*anorm) { flag = false; break; }
              if (cimg::abs(S[nm])<=eps*anorm) break;
            }
            if (flag) {
              c = 0;
              s = 1;
              for (int i = l; i<=k; ++i) {
                f = s*rv1[i];
                rv1[i] = c*rv1[i];
                if ((cimg::abs(f) + anorm)==anorm) break;
                g = S[i];
                h = cimg::hypot(f,g);
                S[i] = h;
                h = 1/h;
                c = g*h;
                s = -f*h;
                cimg_forY(U,j) {
                  const t y = U(nm,j), z = U(i,j);
                  U(nm,j) = y*c + z*s;
                  U(i,j) = z*c - y*s;
                }
              }
            }

            const t z = S[k];
            if (l==k) { if (z<0) { S[k] = -z; cimg_forX(U,j) V(k,j) = -V(k,j); } break; }
            nm = k - 1;
            t x = S[l], y = S[nm];
            g = rv1[nm];
            h = rv1[k];
            f = ((y - z)*(y + z) + (g - h)*(g + h))/std::max(eps,(Ttfloat)2*h*y);
            g = cimg::hypot(f,(Ttfloat)1);
            f = ((x - z)*(x + z) + h*((y/(f + (f>=0?g:-g))) - h))/std::max(eps,(Ttfloat)x);
            c = s = 1;
            for (int j = l; j<=nm; ++j) {
              const int i = j + 1;
              g = rv1[i];
              h = s*g;
              g = c*g;
              t y1 = S[i], z1 = cimg::hypot(f,h);
              rv1[j] = z1;
              c = f/std::max(eps,(Ttfloat)z1);
              s = h/std::max(eps,(Ttfloat)z1);
              f = x*c + g*s;
              g = g*c - x*s;
              h = y1*s;
              y1*=c;
              cimg_forX(U,jj) {
                const t x2 = V(j,jj), z2 = V(i,jj);
                V(j,jj) = x2*c + z2*s;
                V(i,jj) = z2*c - x2*s;
              }
              z1 = cimg::hypot(f,h);
              S[j] = z1;
              if (z1) {
                z1 = 1/std::max(eps,(Ttfloat)z1);
                c = f*z1;
                s = h*z1;
              }
              f = c*g + s*y1;
              x = c*y1 - s*g;
              cimg_forY(U,jj) {
                const t y2 = U(j,jj), z2 = U(i,jj);
                U(j,jj) = y2*c + z2*s;
                U(i,jj) = z2*c - y2*s;
              }
            }
            rv1[l] = 0;
            rv1[k] = f;
            S[k] = x;
          }
        }

        if (sorting) {
          CImg<intT> permutations;
          CImg<t> tmp(_width);
          S.sort(permutations,false);
          cimg_forY(U,k) {
            cimg_forY(permutations,y) tmp(y) = U(permutations(y),k);
            std::memcpy(U.data(0,k),tmp._data,sizeof(t)*_width);
          }
          cimg_forY(V,k) {
            cimg_forY(permutations,y) tmp(y) = V(permutations(y),k);
            std::memcpy(V.data(0,k),tmp._data,sizeof(t)*_width);
          }
        }
      }
      return *this;
    }

    //! Compute the SVD of the instance image, viewed as a general matrix.
    /**
       \return A list of three images <tt>[U; S; V]</tt>, whose meaning is similar as in
         SVD(CImg<t>&,CImg<t>&,CImg<t>&,bool,unsigned int,float) const.
    **/
    CImgList<Tfloat> get_SVD(const bool sorting=true,
                             const unsigned int max_iteration=40, const float lambda=0) const {
      CImgList<Tfloat> res(3);
      SVD(res[0],res[1],res[2],sorting,max_iteration,lambda);
      return res;
    }

    //! Compute the QR decomposition of the instance matrix.
    /**
       Given an instance matrix (*this) of size m×n (m rows, n columns),
       fill the matrices Q and R, so that *this = Q*R (without pivoting) or *this*P = Q*R (with pivoting).
       - Q is an orthogonal matrix, of size 'm×m' if 'is_reduced_form==false', or 'm×min(m,n)' otherwise.
       - R is an upper-triangular matrix of size 'm×n' if 'is_reduced_form==false' or 'min(m,n)×n' otherwise.
       - Q^T*Q = Id.
       - If n>m, only the first m×m part of R is upper triangular.
       - If 'is_pivoting==true', column pivoting is applied and the permutation is stored in 'perm',
       so that the matrix 'A_perm' formed by reordering the columns of *this according to 'perm'
       satisfies A_perm = Q*R, where A_perm(col,row) = (*this)(perm[col],row).
       If 'is_pivoting==false', 'perm' is left unchanged.
    **/
    template<typename t>
    const CImg<T>& QR(CImg<t>& Q, CImg<t>& R, const bool is_reduced_form=true,
                      const bool is_pivoting=false, CImg<uintT> *const perm=0) const {
      if (is_empty()) { Q.assign(); R.assign(); return *this; }
      if (_depth!=1 || _spectrum!=1)
        throw CImgInstanceException(_cimg_instance
                                    "QR(): Instance image is not a matrix.",
                                    cimg_instance);

      const int m = height(), n = width(), k = std::min(m,n);
      CImg<doubleT> _R(*this,false), _Q = CImg<doubleT>::identity_matrix(m);

      // Initialize permutation vector.
      CImg<uintT> _perm;
      if (is_pivoting) {
        _perm.assign(n);
        cimg_forX(_perm,i) _perm[i] = (unsigned int)i;
      }

      for (int j = 0; j<k; ++j) {

        // Apply column pivoting: swap column j with the column of maximum norm among j..n-1.
        if (is_pivoting) {
          int pivot = j;
          double maxnorm = 0;
          for (int col = j; col<n; ++col) {
            double norm = 0;
            for (int i = j; i<m; ++i) norm+=_R(col,i)*_R(col,i);
            if (norm>maxnorm) { maxnorm = norm; pivot = col; }
          }
          if (pivot!=j) {
            for (int i = 0; i<m; ++i) cimg::swap(_R(j,i),_R(pivot,i));
            cimg::swap(_perm[j],_perm[pivot]);
          }
        }

        // Build the Householder vector v.
        CImg<doubleT> x = _R.get_crop(j,j,j,m - 1);
        const double normx = x.magnitude();
        if (normx<1e-15) continue;
        x[0]+=(x[0]>=0?1:-1)*normx;
        x/=x.magnitude();

        // Apply reflection to R.
        cimg_pragma_openmp(parallel for cimg_openmp_if(m*(n - j)>=512*512))
        for (int col = j; col<n; ++col) {
          double dot = 0;
          for (int i = j; i<m; ++i) dot+=x[i - j]*_R(col,i);
          for (int i = j; i<m; ++i) _R(col,i)-=2*x[i - j]*dot;
        }

        // Apply reflection to Q.
        cimg_pragma_openmp(parallel for cimg_openmp_if(m>=512))
        for (int row = 0; row<m; ++row){
          double dot = 0;
          for (int i = j; i<m; ++i) dot+=_Q(i,row)*x[i - j];
          for (int i = j; i<m; ++i) _Q(i,row)-=2*x[i - j]*dot;
        }
      }

      // Force R to be upper-triangular.
      for (int y = 1; y<m; ++y) for (int x = 0; x<std::min(y,n); ++x) _R(x,y) = 0.;
      if (is_reduced_form && m>n) {
        _Q.crop(0,0,n - 1,m - 1);  // Keep only first n columns of Q
        _R.crop(0,0,n - 1,n - 1);  // Keep only top n×n part of R
      }
      _Q.move_to(Q);
      _R.move_to(R);
      if (is_pivoting && perm) _perm.move_to(*perm);
      return *this;
    }

    //! Compute the projection of the instance matrix onto the specified dictionary.
    /**
       Find the best-matching projection of the selected matrix onto the span of an over-complete dictionary D,
       using the orthogonal projection or (optionally Orthogonal) Matching Pursuit algorithm.
       The instance image must be a 2D matrix in which each column represents a signal to project.
       \param dictionary A matrix in which each column is an element of the dictionary D.
       \param method Specifies which projection method is applied. It can be:
         - 0 = orthogonal projection (default).
         - 1 = matching pursuit.
         - 2 = matching pursuit, with a single orthogonal projection step at the end.
         - >=3 = orthogonal matching pursuit where an orthogonal projection step is performed
                 every 'method-2' iterations.
       \param max_iter Sets the max number of iterations processed for each signal.
                       If set to '0' (default), 'max_iter' is set to the number of dictionary columns.
                       (only meaningful for matching pursuit and its variants).
       \param max_residual Provides a stopping criterion based on the signal reconstruction accuracy
                           (only meaningful for matching pursuit and its variants).
       \return A matrix W whose columns correspond to the sparse weights associated with each input matrix column.
               Thus, the matrix product D*W is an approximation of the input matrix.
    **/
    template<typename t>
    CImg<T>& project_matrix(const CImg<t>& dictionary, const unsigned int method=0,
                            const unsigned int max_iter=0, const double max_residual=1e-6) {
      return get_project_matrix(dictionary,method,max_iter,max_residual).move_to(*this);
    }

    template<typename t>
    CImg<Tfloat> get_project_matrix(const CImg<t>& dictionary, const unsigned int method=0,
                                    const unsigned int max_iter=0, const double max_residual=1e-6) const {
      if (_depth!=1 || _spectrum!=1)
        throw CImgInstanceException(_cimg_instance
                                    "project_matrix(): Instance image is not a matrix.",
                                    cimg_instance);
      if (dictionary._height!=_height || dictionary._depth!=1 || dictionary._spectrum!=1)
        throw CImgArgumentException(_cimg_instance
                                    "project_matrix(): Specified dictionary (%u,%u,%u,%u) has an invalid size.",
                                    cimg_instance,
                                    dictionary._width,dictionary._height,dictionary._depth,dictionary._spectrum);
      if (!method) return get_solve(dictionary);

      // Compute norm of dictionary atoms.
      CImg<Tfloat> dictionary_norm(dictionary._width);
      cimg_pragma_openmp(parallel for
                         cimg_openmp_if(dictionary._width>=2 && dictionary._width*dictionary._height>=32))
      cimg_forX(dictionary_norm,atom) {
        Tfloat norm = 0;
        cimg_forY(dictionary,s) norm+=cimg::sqr(dictionary(atom,s));
        dictionary_norm[atom] = std::max((Tfloat)1e-8,std::sqrt(norm));
      }

      // Matching pursuit.
      CImg<Tfloat> weights(_width,dictionary._width,1,1,0);
      const unsigned int proj_step = method<3?1:method - 2;
      bool is_orthoproj = false;

      cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=2 && _width*_height>=32))
      cimg_forX(*this,signal) {
        CImg<Tfloat> R = get_column(signal); // Residual signal
        const CImg<Tfloat> R0 = method<2?CImg<Tfloat>():R;
        Tfloat residual = R.magnitude(2)/R._height;
        const unsigned int _max_iter = max_iter?max_iter:dictionary._width;

        for (unsigned int iter = 0; iter<_max_iter && residual>max_residual; ++iter) {

          // Find best matching column from dictionary D.
          int best_atom = 0;
          Tfloat max_absdot = 0, max_dot = 0;
          cimg_forX(dictionary,atom) {
            Tfloat dot = 0;
            cimg_forY(R,s) dot+=R[s]*dictionary(atom,s);
            dot/=dictionary_norm[atom];
            const Tfloat absdot = cimg::abs(dot);
            if (absdot>max_absdot) { best_atom = atom; max_dot = dot; max_absdot = absdot; }
          }

          if (!iter || method<3 || iter%proj_step) {
            // Matching Pursuit: Subtract component from signal.
            max_dot/=dictionary_norm[best_atom];
            weights(signal,best_atom)+=max_dot;
            residual = 0;
            cimg_forY(R,s) { R[s]-=max_dot*dictionary(best_atom,s); residual+=cimg::sqr(R[s]); }
            residual = std::sqrt(residual)/R._height;
            is_orthoproj = false;

          } else {
            // Orthogonal Matching Pursuit: Orthogonal projection step.
            weights(signal,best_atom) = 1; // Use only as a marker
            unsigned int nb_weights = 0;
            cimg_forY(weights,atom) if (weights(signal,atom)) ++nb_weights;
            CImg<Tfloat> sub_dictionary(nb_weights,dictionary._height);
            CImg<uintT> sub_atoms(nb_weights);
            int ind = 0;
            cimg_forY(weights,atom) if (weights(signal,atom)) {
              cimg_forY(sub_dictionary,s) sub_dictionary(ind,s) = dictionary(atom,s);
              sub_atoms[ind++] = atom;
            }
            const CImg<Tfloat> sub_weights = R0.get_solve(sub_dictionary);

            // Recompute residual signal according to the projected weights.
            R = R0;
            cimg_forY(sub_weights,sub_atom) {
              const Tfloat weight = sub_weights[sub_atom];
              const unsigned int atom = sub_atoms[sub_atom];
              weights(signal,atom) = weight;
              cimg_forY(R,s) R[s]-=weight*dictionary(atom,s);
            }
            residual = R.magnitude(2)/R._height;
            is_orthoproj = true;
          }
        }

        // Perform last orthoprojection step if needed.
        if (method>=2 && !is_orthoproj) {
          unsigned int nb_weights = 0;
          cimg_forY(weights,atom) if (weights(signal,atom)) ++nb_weights;
          if (nb_weights) { // Avoid degenerateds case where 0 coefficients are used
            CImg<Tfloat> sub_dictionary(nb_weights,dictionary._height);
            CImg<uintT> sub_atoms(nb_weights);
            int ind = 0;
            cimg_forY(weights,atom) if (weights(signal,atom)) {
              cimg_forY(sub_dictionary,s) sub_dictionary(ind,s) = dictionary(atom,s);
              sub_atoms[ind++] = atom;
            }
            const CImg<Tfloat> sub_weights = R0.get_solve(sub_dictionary);
            cimg_forY(sub_weights,sub_atom) weights(signal,sub_atoms[sub_atom]) = sub_weights[sub_atom];
          }
        }
      }
      return weights;
    }


    //! Compute minimal path in a graph, using the Dijkstra algorithm.
    /**
       \param distance An object having operator()(unsigned int i, unsigned int j) which returns distance
         between two nodes (i,j).
       \param nb_nodes Number of graph nodes.
       \param starting_node Index of the starting node.
       \param ending_node Index of the ending node (set to ~0U to ignore ending node).
       \param previous_node Array that stores the index of the previous node in the shortest path to the starting node.
         (optional parameter).
       \return Array of distances of each node to the starting node, typed as Tfloat to prevent overflows.
    **/
    template<typename tf, typename t>
    static CImg<Tfloat> dijkstra(const tf& distance, const unsigned int nb_nodes,
                                 const unsigned int starting_node, const unsigned int ending_node,
                                 CImg<t>& previous_node) {
      if (starting_node>=nb_nodes)
        throw CImgArgumentException("CImg<%s>::dijkstra(): Specified index of starting node %u is higher "
                                    "than number of nodes %u.",
                                    pixel_type(),starting_node,nb_nodes);
      CImg<Tfloat> dist(1,nb_nodes,1,1,cimg::type<Tfloat>::max());
      dist(starting_node) = 0;
      previous_node.assign(1,nb_nodes,1,1,(t)-1);
      previous_node(starting_node) = (t)starting_node;
      CImg<uintT> Q(nb_nodes);
      cimg_forX(Q,u) Q(u) = (unsigned int)u;
      cimg::swap(Q(starting_node),Q(0));
      unsigned int sizeQ = nb_nodes;
      while (sizeQ) {
        // Update neighbors from minimal vertex.
        const unsigned int umin = Q(0);
        if (umin==ending_node) sizeQ = 0;
        else {
          const Tfloat
            dmin = dist(umin),
            infty = cimg::type<Tfloat>::max();
          for (unsigned int q = 1; q<sizeQ; ++q) {
            const unsigned int v = Q(q);
            const Tfloat d = (Tfloat)distance(v,umin);
            if (d<infty) {
              const Tfloat alt = dmin + d;
              if (alt<dist(v)) {
                dist(v) = alt;
                previous_node(v) = (t)umin;
                const Tfloat distpos = dist(Q(q));
                for (unsigned int pos = q, par = 0; pos && distpos<dist(Q(par=(pos + 1)/2 - 1)); pos=par)
                  cimg::swap(Q(pos),Q(par));
              }
            }
          }
          // Remove minimal vertex from queue.
          Q(0) = Q(--sizeQ);
          const Tfloat distpos = dist(Q(0));
          for (unsigned int pos = 0, left = 0, right = 0;
               ((right=2*(pos + 1),(left=right - 1))<sizeQ && distpos>dist(Q(left))) ||
                 (right<sizeQ && distpos>dist(Q(right)));) {
            if (right<sizeQ) {
              if (dist(Q(left))<dist(Q(right))) { cimg::swap(Q(pos),Q(left)); pos = left; }
              else { cimg::swap(Q(pos),Q(right)); pos = right; }
            } else { cimg::swap(Q(pos),Q(left)); pos = left; }
          }
        }
      }
      return dist;
    }

    //! Return minimal path in a graph, using the Dijkstra algorithm.
    template<typename tf, typename t>
    static CImg<T> dijkstra(const tf& distance, const unsigned int nb_nodes,
                            const unsigned int starting_node, const unsigned int ending_node=~0U) {
      CImg<uintT> foo;
      return dijkstra(distance,nb_nodes,starting_node,ending_node,foo);
    }

    //! Return minimal path in a graph, using the Dijkstra algorithm.
    /**
       \param starting_node Index of the starting node.
       \param ending_node Index of the ending node.
       \param previous_node Array that gives the previous node index in the path to the starting node
         (optional parameter).
       \return Array of distances of each node to the starting node.
       \note image instance corresponds to the adjacency matrix of the graph.
    **/
    template<typename t>
    CImg<T>& dijkstra(const unsigned int starting_node, const unsigned int ending_node,
                      CImg<t>& previous_node) {
      return get_dijkstra(starting_node,ending_node,previous_node).move_to(*this);
    }

    //! Return minimal path in a graph, using the Dijkstra algorithm \newinstance.
    template<typename t>
    CImg<T> get_dijkstra(const unsigned int starting_node, const unsigned int ending_node,
                         CImg<t>& previous_node) const {
      if (_width!=_height || _depth!=1 || _spectrum!=1)
        throw CImgInstanceException(_cimg_instance
                                    "dijkstra(): Instance is not a graph adjacency matrix.",
                                    cimg_instance);

      return dijkstra(*this,_width,starting_node,ending_node,previous_node);
    }

    //! Return minimal path in a graph, using the Dijkstra algorithm.
    CImg<T>& dijkstra(const unsigned int starting_node, const unsigned int ending_node=~0U) {
      return get_dijkstra(starting_node,ending_node).move_to(*this);
    }

    //! Return minimal path in a graph, using the Dijkstra algorithm \newinstance.
    CImg<Tfloat> get_dijkstra(const unsigned int starting_node, const unsigned int ending_node=~0U) const {
      CImg<uintT> foo;
      return get_dijkstra(starting_node,ending_node,foo);
    }

    //! Return an image containing the character codes of specified string.
    /**
       \param str input C-string to encode as an image.
       \param is_last_zero Indicates whether the terminating null character ('\0') appears in the resulting image.
       \param is_shared Specifies whether the returned image shares its buffer with \p str.
    **/
    static CImg<T> string(const char *const str, const bool is_last_zero=true, const bool is_shared=false) {
      if (!str) return CImg<T>();
      return CImg<T>(str,(unsigned int)std::strlen(str) + (is_last_zero?1:0),1,1,1,is_shared);
    }

    //! Return a \c 1x1 image containing specified value.
    /**
       \param a0 First vector value.
    **/
    static CImg<T> row_vector(const T& a0) {
      return vector(a0);
    }

    //! Return a \c 2x1 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
    **/
    static CImg<T> row_vector(const T& a0, const T& a1) {
      CImg<T> r(2,1);
      r[0] = a0; r[1] = a1;
      return r;
    }

    //! Return a \c 3x1 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
       \param a2 Third vector value.
    **/
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2) {
      CImg<T> r(3,1);
      r[0] = a0; r[1] = a1; r[2] = a2;
      return r;
    }

    //! Return a \c 4x1 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
       \param a2 Third vector value.
       \param a3 Fourth vector value.
    **/
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3) {
      CImg<T> r(4,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3;
      return r;
    }

    //! Return a \c 5x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4) {
      CImg<T> r(5,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4;
      return r;
    }

    //! Return a \c 6x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4, const T& a5) {
      CImg<T> r(6,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5;
      return r;
    }

    //! Return a \c 7x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6) {
      CImg<T> r(7,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6;
      return r;
    }

    //! Return a \c 8x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7) {
      CImg<T> r(8,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7;
      return r;
    }

    //! Return a \c 9x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8) {
      CImg<T> r(9,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8;
      return r;
    }

    //! Return a \c 10x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9) {
      CImg<T> r(10,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      return r;
    }

    //! Return a \c 11x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10) {
      CImg<T> r(11,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10;
      return r;
    }

    //! Return a \c 12x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10, const T& a11) {
      CImg<T> r(12,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11;
      return r;
    }

    //! Return a \c 13x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10, const T& a11,
                              const T& a12) {
      CImg<T> r(13,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12;
      return r;
    }

    //! Return a \c 14x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10, const T& a11,
                              const T& a12, const T& a13) {
      CImg<T> r(14,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13;
      return r;
    }

    //! Return a \c 15x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10, const T& a11,
                              const T& a12, const T& a13, const T& a14) {
      CImg<T> r(15,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14;
      return r;
    }

    //! Return a \c 16x1 image containing specified values.
    static CImg<T> row_vector(const T& a0, const T& a1, const T& a2, const T& a3,
                              const T& a4, const T& a5, const T& a6, const T& a7,
                              const T& a8, const T& a9, const T& a10, const T& a11,
                              const T& a12, const T& a13, const T& a14, const T& a15) {
      CImg<T> r(16,1);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15;
      return r;
    }

    //! Return a \c 1x1 image containing specified value.
    /**
       \param a0 First vector value.
    **/
    static CImg<T> vector(const T& a0) {
      CImg<T> r(1,1);
      r[0] = a0;
      return r;
    }

    //! Return a \c 1x2 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
    **/
    static CImg<T> vector(const T& a0, const T& a1) {
      CImg<T> r(1,2);
      r[0] = a0; r[1] = a1;
      return r;
    }

    //! Return a \c 1x3 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
       \param a2 Third vector value.
    **/
    static CImg<T> vector(const T& a0, const T& a1, const T& a2) {
      CImg<T> r(1,3);
      r[0] = a0; r[1] = a1; r[2] = a2;
      return r;
    }

    //! Return a \c 1x4 image containing specified values.
    /**
       \param a0 First vector value.
       \param a1 Second vector value.
       \param a2 Third vector value.
       \param a3 Fourth vector value.
    **/
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3) {
      CImg<T> r(1,4);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3;
      return r;
    }

    //! Return a \c 1x5 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4) {
      CImg<T> r(1,5);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4;
      return r;
    }

    //! Return a \c 1x6 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4, const T& a5) {
      CImg<T> r(1,6);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5;
      return r;
    }

    //! Return a \c 1x7 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6) {
      CImg<T> r(1,7);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6;
      return r;
    }

    //! Return a \c 1x8 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7) {
      CImg<T> r(1,8);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7;
      return r;
    }

    //! Return a \c 1x9 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8) {
      CImg<T> r(1,9);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8;
      return r;
    }

    //! Return a \c 1x10 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9) {
      CImg<T> r(1,10);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      return r;
    }

    //! Return a \c 1x11 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10) {
      CImg<T> r(1,11);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10;
      return r;
    }

    //! Return a \c 1x12 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11) {
      CImg<T> r(1,12);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11;
      return r;
    }

    //! Return a \c 1x13 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12) {
      CImg<T> r(1,13);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12;
      return r;
    }

    //! Return a \c 1x14 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13) {
      CImg<T> r(1,14);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13;
      return r;
    }

    //! Return a \c 1x15 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14) {
      CImg<T> r(1,15);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14;
      return r;
    }

    //! Return a \c 1x16 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15) {
      CImg<T> r(1,16);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15;
      return r;
    }

    //! Return a \c 1x17 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15,
                          const T& a16) {
      CImg<T> r(1,17);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15; r[16] = a16;
      return r;
    }

    //! Return a \c 1x18 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15,
                          const T& a16, const T& a17) {
      CImg<T> r(1,18);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15; r[16] = a16; r[17] = a17;
      return r;
    }

    //! Return a \c 1x19 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15,
                          const T& a16, const T& a17, const T& a18) {
      CImg<T> r(1,19);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15; r[16] = a16; r[17] = a17;
      r[18] = a18;
      return r;
    }

    //! Return a \c 1x20 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15,
                          const T& a16, const T& a17, const T& a18, const T& a19) {
      CImg<T> r(1,20);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15; r[16] = a16; r[17] = a17;
      r[18] = a18; r[19] = a19;
      return r;
    }

    //! Return a \c 1x21 image containing specified values.
    static CImg<T> vector(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15,
                          const T& a16, const T& a17, const T& a18, const T& a19,
                          const T& a20) {
      CImg<T> r(1,21);
      r[0] = a0; r[1] = a1; r[2] = a2; r[3] = a3; r[4] = a4; r[5] = a5; r[6] = a6; r[7] = a7; r[8] = a8; r[9] = a9;
      r[10] = a10; r[11] = a11; r[12] = a12; r[13] = a13; r[14] = a14; r[15] = a15; r[16] = a16; r[17] = a17;
      r[18] = a18; r[19] = a19; r[20] = a20;
      return r;
    }

    //! Return a 1x1 matrix containing specified coefficients.
    /**
       \param a0 First matrix value.
       \note Equivalent to vector(const T&).
    **/
    static CImg<T> matrix(const T& a0) {
      return vector(a0);
    }

    //! Return a 2x2 matrix containing specified coefficients.
    /**
       \param a0 First matrix value.
       \param a1 Second matrix value.
       \param a2 Third matrix value.
       \param a3 Fourth matrix value.
    **/
    static CImg<T> matrix(const T& a0, const T& a1,
                          const T& a2, const T& a3) {
      CImg<T> r(2,2); T *ptr = r._data;
      *(ptr++) = a0; *(ptr++) = a1;
      *(ptr++) = a2; *(ptr++) = a3;
      return r;
    }

    //! Return a 3x3 matrix containing specified coefficients.
    /**
       \param a0 First matrix value.
       \param a1 Second matrix value.
       \param a2 Third matrix value.
       \param a3 Fourth matrix value.
       \param a4 Fifth matrix value.
       \param a5 Sixth matrix value.
       \param a6 Seventh matrix value.
       \param a7 Eighth matrix value.
       \param a8 Ninth matrix value.
    **/
    static CImg<T> matrix(const T& a0, const T& a1, const T& a2,
                          const T& a3, const T& a4, const T& a5,
                          const T& a6, const T& a7, const T& a8) {
      CImg<T> r(3,3); T *ptr = r._data;
      *(ptr++) = a0; *(ptr++) = a1; *(ptr++) = a2;
      *(ptr++) = a3; *(ptr++) = a4; *(ptr++) = a5;
      *(ptr++) = a6; *(ptr++) = a7; *(ptr++) = a8;
      return r;
    }

    //! Return a 4x4 matrix containing specified coefficients.
    static CImg<T> matrix(const T& a0, const T& a1, const T& a2, const T& a3,
                          const T& a4, const T& a5, const T& a6, const T& a7,
                          const T& a8, const T& a9, const T& a10, const T& a11,
                          const T& a12, const T& a13, const T& a14, const T& a15) {
      CImg<T> r(4,4); T *ptr = r._data;
      *(ptr++) = a0; *(ptr++) = a1; *(ptr++) = a2; *(ptr++) = a3;
      *(ptr++) = a4; *(ptr++) = a5; *(ptr++) = a6; *(ptr++) = a7;
      *(ptr++) = a8; *(ptr++) = a9; *(ptr++) = a10; *(ptr++) = a11;
      *(ptr++) = a12; *(ptr++) = a13; *(ptr++) = a14; *(ptr++) = a15;
      return r;
    }

    //! Return a 5x5 matrix containing specified coefficients.
    static CImg<T> matrix(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4,
                          const T& a5, const T& a6, const T& a7, const T& a8, const T& a9,
                          const T& a10, const T& a11, const T& a12, const T& a13, const T& a14,
                          const T& a15, const T& a16, const T& a17, const T& a18, const T& a19,
                          const T& a20, const T& a21, const T& a22, const T& a23, const T& a24) {
      CImg<T> r(5,5); T *ptr = r._data;
      *(ptr++) = a0; *(ptr++) = a1; *(ptr++) = a2; *(ptr++) = a3; *(ptr++) = a4;
      *(ptr++) = a5; *(ptr++) = a6; *(ptr++) = a7; *(ptr++) = a8; *(ptr++) = a9;
      *(ptr++) = a10; *(ptr++) = a11; *(ptr++) = a12; *(ptr++) = a13; *(ptr++) = a14;
      *(ptr++) = a15; *(ptr++) = a16; *(ptr++) = a17; *(ptr++) = a18; *(ptr++) = a19;
      *(ptr++) = a20; *(ptr++) = a21; *(ptr++) = a22; *(ptr++) = a23; *(ptr++) = a24;
      return r;
    }

    //! Return a 1x1 symmetric matrix containing specified coefficients.
    /**
       \param a0 First matrix value.
       \note Equivalent to vector(const T&).
    **/
    static CImg<T> tensor(const T& a0) {
      return matrix(a0);
    }

    //! Return a 2x2 symmetric matrix tensor containing specified coefficients.
    static CImg<T> tensor(const T& a0, const T& a1, const T& a2) {
      return matrix(a0,a1,a1,a2);
    }

    //! Return a 3x3 symmetric matrix containing specified coefficients.
    static CImg<T> tensor(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4, const T& a5) {
      return matrix(a0,a1,a2,a1,a3,a4,a2,a4,a5);
    }

    //! Return a 1x1 diagonal matrix containing specified coefficients.
    static CImg<T> diagonal(const T& a0) {
      return matrix(a0);
    }

    //! Return a 2x2 diagonal matrix containing specified coefficients.
    static CImg<T> diagonal(const T& a0, const T& a1) {
      return matrix(a0,0,0,a1);
    }

    //! Return a 3x3 diagonal matrix containing specified coefficients.
    static CImg<T> diagonal(const T& a0, const T& a1, const T& a2) {
      return matrix(a0,0,0,0,a1,0,0,0,a2);
    }

    //! Return a 4x4 diagonal matrix containing specified coefficients.
    static CImg<T> diagonal(const T& a0, const T& a1, const T& a2, const T& a3) {
      return matrix(a0,0,0,0,0,a1,0,0,0,0,a2,0,0,0,0,a3);
    }

    //! Return a 5x5 diagonal matrix containing specified coefficients.
    static CImg<T> diagonal(const T& a0, const T& a1, const T& a2, const T& a3, const T& a4) {
      return matrix(a0,0,0,0,0,0,a1,0,0,0,0,0,a2,0,0,0,0,0,a3,0,0,0,0,0,a4);
    }

    //! Return a NxN identity matrix.
    /**
       \param N Dimension of the matrix.
    **/
    static CImg<T> identity_matrix(const unsigned int N) {
      CImg<T> res(N,N,1,1,0);
      cimg_forX(res,x) res(x,x) = 1;
      return res;
    }

    //! Return a N-numbered sequence vector from \p a0 to \p a1.
    /**
       \param N Size of the resulting vector.
       \param a0 Starting value of the sequence.
       \param a1 Ending value of the sequence.
     **/
    static CImg<T> sequence(const unsigned int N, const T& a0, const T& a1) {
      if (N) return CImg<T>(1,N).sequence(a0,a1);
      return CImg<T>();
    }

    //! Return a 3x3 rotation matrix from an { axis + angle } or a quaternion.
    /**
       \param x X-coordinate of the rotation axis, or first quaternion coordinate.
       \param y Y-coordinate of the rotation axis, or second quaternion coordinate.
       \param z Z-coordinate of the rotation axis, or third quaternion coordinate.
       \param w Angle of the rotation axis (in degree), or fourth quaternion coordinate.
       \param is_quaternion Tell is the four arguments denotes a set { axis + angle } or a quaternion (x,y,z,w).
     **/
    static CImg<T> rotation_matrix(const float x, const float y, const float z, const float w,
                                   const bool is_quaternion=false) {
      double X, Y, Z, W, N;
      if (is_quaternion) {
        N = std::sqrt((double)x*x + (double)y*y + (double)z*z + (double)w*w);
        if (N>0) { X = x/N; Y = y/N; Z = z/N; W = w/N; }
        else { X = Y = Z = 0; W = 1; }
        return CImg<T>::matrix((T)(W*W + X*X - Y*Y - Z*Z),(T)(2*X*Y - 2*Z*W),(T)(2*X*Z + 2*Y*W),
                               (T)(2*X*Y + 2*Z*W),(T)(W*W - X*X + Y*Y - Z*Z),(T)(2*Y*Z - 2*X*W),
                               (T)(2*X*Z - 2*Y*W),(T)(2*Y*Z + 2*X*W),(T)(W*W - X*X - Y*Y + Z*Z));
      }
      N = cimg::hypot((double)x,(double)y,(double)z);
      if (N>0) { X = x/N; Y = y/N; Z = z/N; }
      else { X = Y = 0; Z = 1; }
      const double ang = w*cimg::PI/180, c = std::cos(ang), omc = 1 - c, s = std::sin(ang);
      return CImg<T>::matrix((T)(X*X*omc + c),(T)(X*Y*omc - Z*s),(T)(X*Z*omc + Y*s),
                             (T)(X*Y*omc + Z*s),(T)(Y*Y*omc + c),(T)(Y*Z*omc - X*s),
                             (T)(X*Z*omc - Y*s),(T)(Y*Z*omc + X*s),(T)(Z*Z*omc + c));
    }

    //@}
    //-----------------------------------
    //
    //! \name Value Manipulation
    //@{
    //-----------------------------------

    //! Fill all pixel values with specified value.
    /**
       \param val Fill value.
    **/
    CImg<T>& fill(const T& val) {
      if (is_empty()) return *this;
      if (val && sizeof(T)!=1) cimg_for(*this,ptrd,T) *ptrd = val;
      else std::memset(_data,(int)(ulongT)val,sizeof(T)*size()); // Double cast to allow val to be (void*)
      return *this;
    }

    //! Fill all pixel values with specified value \newinstance.
    CImg<T> get_fill(const T& val) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val);
    }

    //! Fill sequentially all pixel values with specified values.
    /**
       \param val0 First fill value.
       \param val1 Second fill value.
    **/
    CImg<T>& fill(const T& val0, const T& val1) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 1;
      for (ptrd = _data; ptrd<ptre; ) { *(ptrd++) = val0; *(ptrd++) = val1; }
      if (ptrd!=ptre + 1) *(ptrd++) = val0;
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 2;
      for (ptrd = _data; ptrd<ptre; ) { *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; }
      ptre+=2;
      switch (ptre - ptrd) {
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 3;
      for (ptrd = _data; ptrd<ptre; ) { *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; }
      ptre+=3;
      switch (ptre - ptrd) {
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 4;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4;
      }
      ptre+=4;
      switch (ptre - ptrd) {
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 5;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
      }
      ptre+=5;
      switch (ptre - ptrd) {
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 6;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6;
      }
      ptre+=6;
      switch (ptre - ptrd) {
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 7;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3;
        *(ptrd++) = val4; *(ptrd++) = val5; *(ptrd++) = val6; *(ptrd++) = val7;
      }
      ptre+=7;
      switch (ptre - ptrd) {
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 8;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2;
        *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8;
      }
      ptre+=8;
      switch (ptre - ptrd) {
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 9;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4;
        *(ptrd++) = val5; *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9;
      }
      ptre+=9;
      switch (ptre - ptrd) {
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 10;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4;
        *(ptrd++) = val5; *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9;
        *(ptrd++) = val10;
      }
      ptre+=10;
      switch (ptre - ptrd) {
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 11;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9; *(ptrd++) = val10; *(ptrd++) = val11;
      }
      ptre+=11;
      switch (ptre - ptrd) {
      case 11 : *(--ptre) = val10; // Fallthrough
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10,
                                                           val11);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                  const T& val12) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 12;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9; *(ptrd++) = val10; *(ptrd++) = val11;
        *(ptrd++) = val12;
      }
      ptre+=12;
      switch (ptre - ptrd) {
      case 12 : *(--ptre) = val11; // Fallthrough
      case 11 : *(--ptre) = val10; // Fallthrough
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                     const T& val12) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10,
                                                           val11,val12);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                  const T& val12, const T& val13) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 13;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9; *(ptrd++) = val10; *(ptrd++) = val11;
        *(ptrd++) = val12; *(ptrd++) = val13;
      }
      ptre+=13;
      switch (ptre - ptrd) {
      case 13 : *(--ptre) = val12; // Fallthrough
      case 12 : *(--ptre) = val11; // Fallthrough
      case 11 : *(--ptre) = val10; // Fallthrough
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                     const T& val12, const T& val13) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10,
                                                           val11,val12,val13);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                  const T& val12, const T& val13, const T& val14) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 14;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9; *(ptrd++) = val10; *(ptrd++) = val11;
        *(ptrd++) = val12; *(ptrd++) = val13; *(ptrd++) = val14;
      }
      ptre+=14;
      switch (ptre - ptrd) {
      case 14 : *(--ptre) = val13; // Fallthrough
      case 13 : *(--ptre) = val12; // Fallthrough
      case 12 : *(--ptre) = val11; // Fallthrough
      case 11 : *(--ptre) = val10; // Fallthrough
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                     const T& val12, const T& val13, const T& val14) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10,
                                                           val11,val12,val13,val14);
    }

    //! Fill sequentially all pixel values with specified values \overload.
    CImg<T>& fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                  const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                  const T& val12, const T& val13, const T& val14, const T& val15) {
      if (is_empty()) return *this;
      T *ptrd, *ptre = end() - 15;
      for (ptrd = _data; ptrd<ptre; ) {
        *(ptrd++) = val0; *(ptrd++) = val1; *(ptrd++) = val2; *(ptrd++) = val3; *(ptrd++) = val4; *(ptrd++) = val5;
        *(ptrd++) = val6; *(ptrd++) = val7; *(ptrd++) = val8; *(ptrd++) = val9; *(ptrd++) = val10; *(ptrd++) = val11;
        *(ptrd++) = val12; *(ptrd++) = val13; *(ptrd++) = val14; *(ptrd++) = val15;
      }
      ptre+=15;
      switch (ptre - ptrd) {
      case 15 : *(--ptre) = val14; // Fallthrough
      case 14 : *(--ptre) = val13; // Fallthrough
      case 13 : *(--ptre) = val12; // Fallthrough
      case 12 : *(--ptre) = val11; // Fallthrough
      case 11 : *(--ptre) = val10; // Fallthrough
      case 10 : *(--ptre) = val9; // Fallthrough
      case 9 : *(--ptre) = val8; // Fallthrough
      case 8 : *(--ptre) = val7; // Fallthrough
      case 7 : *(--ptre) = val6; // Fallthrough
      case 6 : *(--ptre) = val5; // Fallthrough
      case 5 : *(--ptre) = val4; // Fallthrough
      case 4 : *(--ptre) = val3; // Fallthrough
      case 3 : *(--ptre) = val2; // Fallthrough
      case 2 : *(--ptre) = val1; // Fallthrough
      case 1 : *(--ptre) = val0; // Fallthrough
      }
      return *this;
    }

    //! Fill sequentially all pixel values with specified values \newinstance.
    CImg<T> get_fill(const T& val0, const T& val1, const T& val2, const T& val3, const T& val4, const T& val5,
                     const T& val6, const T& val7, const T& val8, const T& val9, const T& val10, const T& val11,
                     const T& val12, const T& val13, const T& val14, const T& val15) const {
      return CImg<T>(_width,_height,_depth,_spectrum).fill(val0,val1,val2,val3,val4,val5,val6,val7,val8,val9,val10,
                                                           val11,val12,val13,val14,val15);
    }

    //! Fill sequentially pixel values according to a given expression.
    /**
       \param expression C-string describing a math formula, or a sequence of values.
       \param repeat_values In case a list of values is provided, indicates that this list must be repeated for the
                            filling.
       \param allow_formula Indicates that mathematical formulas are authorized for the filling.
       \param list_images In case of a mathematical expression, attach a list of images to the specified expression.
    **/
    CImg<T>& fill(const char *const expression, const bool repeat_values, const bool allow_formula=true,
                  CImgList<T> *const list_images=0) {
      return _fill(expression,repeat_values,allow_formula?3:1,list_images,"fill",0,0);
    }

    // bits of 'mode' can enable/disable these properties:
    // . 1 = Allow list of values.
    // . 2 = Allow formula.
    // . 4 = Evaluate but does not fill image values.
    template<typename t>
    CImg<T>& _fill(const char *const expression, const bool repeat_values, const unsigned int mode,
                   CImgList<t> *const list_images, const char *const calling_function,
                   const CImg<T> *provides_copy, CImg<doubleT> *const result_end) {
      if (!expression || !*expression) return *this; // But empty images be evaluated to allow side effects
      typedef typename CImg<t>::_cimg_math_parser _cimg_math_parser_t;
      const unsigned int excmode = cimg::exception_mode();
      cimg::exception_mode(0);
      CImg<charT> is_error_expr;
      bool is_done = false, is_value_sequence = false;
      cimg_abort_init;
      if (result_end) result_end->assign();

      // Detect value sequence.
      if (mode&1) {
        double value;
        char sep;
        const int err = cimg_sscanf(expression,"%lf %c",&value,&sep);
        if (err==1 || (err==2 && sep==',')) {
          if (err==1) { if (mode&4) return *this; return fill((T)value); }
          else is_value_sequence = true;
        }
      }

      // Try to fill values according to a formula.
      if (mode&2 && !is_value_sequence) {
        _cimg_abort_init_openmp;
        try {
          CImg<t> base;
          if (cimg::type<T>::string()==cimg::type<t>::string())
            base.assign(provides_copy?*provides_copy:*this,true);
          else
            base = provides_copy?*provides_copy:*this;

          _cimg_math_parser_t mp(expression + (*expression=='>' || *expression=='<' ||
                                               (*expression=='+' && expression[1]!='+') ||
                                               *expression=='*' || *expression==':'),
                                 calling_function,base,
                                 cimg::type<T>::string()==cimg::type<t>::string()?(CImg<t>*)this:&base,
                                 list_images,true);
          if (!provides_copy && expression &&
              *expression!='>' && *expression!='<' && *expression!=':' &&
              mp.need_input_copy)
            base.assign().assign(*this,false); // Needs input copy

          // Determine M2, smallest image dimension (used as axis for the most inner loop in parallelized iterations).
          // M1 is the total number of parallelized iterations.
          unsigned int M1 = 0, M2 = 0;
          cimg::unused(M1,M2);
          if (mp.result_dim) {
            M2 = cimg::min(_width,_height,_depth);
            M1 = M2==_width?_height*_depth:M2==_height?_width*_depth:_width*_height;
          } else {
            M2 = cimg::min(_width,_height,_depth,_spectrum);
            M1 = M2==_width?_height*_depth*_spectrum:M2==_height?_width*_depth*_spectrum:
              M2==_depth?_width*_height*_spectrum:_width*_height*_depth;
          }

          bool is_parallelizable = false;
          cimg_openmp_if(*expression=='*' || *expression==':' || (mp.is_parallelizable &&
                                                                  (M2>=2 || M1>=4096) && M1*M2>=32))
            is_parallelizable = true;

          if (mp.result_dim) { // Vector-valued expression
            const unsigned int N = std::min(mp.result_dim,_spectrum);
            const ulongT whd = (ulongT)_width*_height*_depth;
            T *ptrd = *expression=='<'?_data + _width*_height*_depth - 1:_data;

            if (*expression=='<') {
              CImg<doubleT> res(1,mp.result_dim);
              mp.begin_t();
              cimg_rofYZ(*this,y,z) {
                cimg_abort_test;
                if (mode&4) cimg_rofX(*this,x) mp(x,y,z,0);
                else cimg_rofX(*this,x) {
                    mp(x,y,z,0,res._data);
                    const double *const ptrs = res._data;
                    T *_ptrd = ptrd--;
                    for (unsigned int n = 0; n<N; ++n) _ptrd[n*whd] = (T)ptrs[n];
                  }
              }
              mp.end_t();

            } else if (*expression=='>' || *expression=='+' || !is_parallelizable) {
              CImg<doubleT> res(1,mp.result_dim);
              mp.begin_t();
              cimg_forYZ(*this,y,z) {
                cimg_abort_test;
                if (mode&4) cimg_forX(*this,x) mp(x,y,z,0);
                else cimg_forX(*this,x) {
                    mp(x,y,z,0,res._data);
                    const double *const ptrs = res._data;
                    T *_ptrd = ptrd++;
                    for (unsigned int n = 0; n<N; ++n) _ptrd[n*whd] = (T)ptrs[n];
                  }
              }
              mp.end_t();

            } else {

#if cimg_use_openmp!=0
              const int num_threads = (int)std::min(size(),(ulongT)omp_get_max_threads());
              cimg_pragma_openmp(parallel if (num_threads>0) num_threads(num_threads)) {
                _cimg_math_parser_t
                  *const _mp = omp_get_thread_num()?new _cimg_math_parser_t(mp):&mp,
                  &lmp = *_mp;
                lmp.is_fill = true;
                cimg_pragma_openmp(barrier)
                lmp.begin_t();

#define _cimg_fill_openmp_vector(_YZ,_y,_z,_X,_x,_sx,_sy,_sz,_off) \
  cimg_pragma_openmp(for cimg_openmp_collapse(2)) \
  cimg_for##_YZ(*this,_y,_z) _cimg_abort_try_openmp { \
    cimg_abort_test; \
    if (mode&4) cimg_for##_X(*this,_x) lmp(x,y,z,0); \
    else { \
      CImg<doubleT> res(1,lmp.result_dim); \
      T *__ptrd = data(_sx,_sy,_sz,0); \
      const ulongT off = (ulongT)_off; \
      cimg_for##_X(*this,_x) { \
        lmp(x,y,z,0,res._data); \
        const double *const ptrs = res._data; \
        T *_ptrd = __ptrd; \
        for (unsigned int n = 0; n<N; ++n) _ptrd[n*whd] = (T)ptrs[n]; \
        __ptrd+=off; \
      } \
    } \
  } _cimg_abort_catch_openmp _cimg_abort_catch_fill_openmp

                if (M2==_width) { _cimg_fill_openmp_vector(YZ,y,z,X,x,0,y,z,1) }
                else if (M2==_height) { _cimg_fill_openmp_vector(XZ,x,z,Y,y,x,0,z,_width) }
                else { _cimg_fill_openmp_vector(XY,x,y,Z,z,x,y,0,_width*_height) }

                lmp.end_t();
                cimg_pragma_openmp(barrier) cimg_pragma_openmp(critical) { lmp.merge(mp); }
                if (&lmp!=&mp) delete &lmp;
              }
#endif
            }

          } else { // Scalar-valued expression
            T *ptrd = *expression=='<'?end() - 1:_data;
            if (*expression=='<') {
              mp.begin_t();
              if (mode&4) cimg_rofYZC(*this,y,z,c) { cimg_abort_test; cimg_rofX(*this,x) mp(x,y,z,c); }
              else cimg_rofYZC(*this,y,z,c) { cimg_abort_test; cimg_rofX(*this,x) *(ptrd--) = (T)mp(x,y,z,c); }
              mp.end_t();

            } else if (*expression=='>' || *expression=='+' || !is_parallelizable) {
              mp.begin_t();
              if (mode&4) cimg_forYZC(*this,y,z,c) { cimg_abort_test; cimg_forX(*this,x) mp(x,y,z,c); }
              else cimg_forYZC(*this,y,z,c) { cimg_abort_test; cimg_forX(*this,x) *(ptrd++) = (T)mp(x,y,z,c); }
              mp.end_t();

            } else {

#if cimg_use_openmp!=0
              const int num_threads = (int)std::min(size(),(ulongT)omp_get_max_threads());
              cimg_pragma_openmp(parallel if (num_threads>0) num_threads(num_threads)) {
                _cimg_math_parser_t
                  *const _mp = omp_get_thread_num()?new _cimg_math_parser_t(mp):&mp,
                  &lmp = *_mp;
                lmp.is_fill = true;
                cimg_pragma_openmp(barrier)
                lmp.begin_t();

#define _cimg_fill_openmp_scalar(_YZC,_y,_z,_c,_X,_x,_sx,_sy,_sz,_sc,_off) \
  cimg_pragma_openmp(for cimg_openmp_collapse(3)) \
  cimg_for##_YZC(*this,_y,_z,_c) _cimg_abort_try_openmp { \
    cimg_abort_test; \
    if (mode&4) cimg_for##_X(*this,_x) lmp(x,y,z,c); \
    else { \
      T *const _ptrd = data(_sx,_sy,_sz,_sc); \
      const ulongT off = (ulongT)_off; \
      cimg_for##_X(*this,_x) _ptrd[_x*off] = (T)lmp(x,y,z,c); \
    } \
  } _cimg_abort_catch_openmp _cimg_abort_catch_fill_openmp

                if (M2==_width) { _cimg_fill_openmp_scalar(YZC,y,z,c,X,x,0,y,z,c,1) }
                else if (M2==_height) { _cimg_fill_openmp_scalar(XZC,x,z,c,Y,y,x,0,z,c,_width) }
                else if (M2==_depth) { _cimg_fill_openmp_scalar(XYC,x,y,c,Z,z,x,y,0,c,_width*_height) }
                else { _cimg_fill_openmp_scalar(XYZ,x,y,z,C,c,x,y,z,0,_width*_height*_depth) }

                lmp.end_t();
                cimg_pragma_openmp(barrier) cimg_pragma_openmp(critical) { lmp.merge(mp); }
                if (&lmp!=&mp) delete &lmp;
              }
#endif
            }
          }
          mp.end();

          if (result_end && mp.result_end) // Transfer result of the end() block if requested
            result_end->assign(mp.result_end + (mp.result_end_dim?1:0),std::max(1U,mp.result_end_dim));

          is_done = true;
        } catch (CImgException& e) { CImg<charT>::string(e._message).move_to(is_error_expr); }
      }

      // Try to fill values according to a value sequence.
      if (!is_done && mode&1) is_done = !_fill_from_values(expression,repeat_values);

      if (!is_done) {
        cimg::exception_mode(excmode);
        if (is_error_expr) throw CImgArgumentException(_cimg_instance
                                                       "%s",
                                                       cimg_instance,is_error_expr._data);
        else throw CImgArgumentException(_cimg_instance
                                         "%s(): Invalid sequence of filling values '%s'.",
                                         cimg_instance,calling_function,expression);
      }
      cimg::exception_mode(excmode);
      cimg_abort_test;
      return *this;
    }

    //! Fill sequentially pixel values according to a given expression \newinstance.
    CImg<T> get_fill(const char *const expression, const bool repeat_values, const bool allow_formula=true,
                     CImgList<T> *const list_images=0) const {
      return (+*this)._fill(expression,repeat_values,allow_formula?3:1,list_images,"fill",this,0);
    }

    //! Fill sequentially pixel values according to a value sequence, given as a string.
    /**
       \param values C-string describing a sequence of values.
       \param repeat_values Indicates whether this sequence must be repeated when filling.
    **/
    CImg<T>& fill_from_values(const char *const values, const bool repeat_values) {
      if (_fill_from_values(values,repeat_values))
        throw CImgArgumentException(_cimg_instance
                                    "Invalid sequence of filling values '%s'.",
                                    cimg_instance,values);
      return *this;
    }

    //! Fill sequentially pixel values according to a value sequence, given as a string \newinstance.
    CImg<T> get_fill_from_values(const char *const values, const bool repeat_values) const {
      return (+*this).fill_from_values(values,repeat_values);
    }

    // Fill image according to a value sequence, given as a string.
    // Return 'true' if an error occurred, 'false' otherwise.
    bool _fill_from_values(const char *const values, const bool repeat_values) {
      CImg<charT> item(256);
      const char *nvalues = values;
      const ulongT siz = size();
      T *ptrd = _data;
      ulongT nb = 0;
      char sep = 0;
      for (double val = 0; *nvalues && nb<siz; ++nb) {
        sep = 0;
        const int err = cimg_sscanf(nvalues,"%255[ \n\t0-9.eEinfa+-]%c",item._data,&sep);
        if (err>0 && cimg_sscanf(item._data,"%lf",&val)==1 && (sep==',' || sep==';' || err==1)) {
          nvalues+=std::strlen(item) + (err>1);
          *(ptrd++) = (T)val;
        } else break;
      }
      if (nb<siz && (sep || *nvalues)) return true;
      if (repeat_values && nb && nb<siz)
        for (T *ptrs = _data, *const ptre = _data + siz; ptrd<ptre; ++ptrs) *(ptrd++) = *ptrs;
      return false;
    }

    //! Fill sequentially pixel values according to the values found in another image.
    /**
       \param values Image containing the values used for the filling.
       \param repeat_values In case there are less values than necessary in \c values,
                            indicates that these values must be repeated for the filling.
    **/
    template<typename t>
    CImg<T>& fill(const CImg<t>& values, const bool repeat_values=true) {
      if (is_empty() || !values) return *this;
      T *ptrd = _data, *ptre = ptrd + size();
      for (t *ptrs = values._data, *ptrs_end = ptrs + values.size(); ptrs<ptrs_end && ptrd<ptre; ++ptrs)
        *(ptrd++) = (T)*ptrs;
      if (repeat_values && ptrd<ptre) for (T *ptrs = _data; ptrd<ptre; ++ptrs) *(ptrd++) = *ptrs;
      return *this;
    }

    //! Fill sequentially pixel values according to the values found in another image \newinstance.
    template<typename t>
    CImg<T> get_fill(const CImg<t>& values, const bool repeat_values=true) const {
      return repeat_values?CImg<T>(_width,_height,_depth,_spectrum).fill(values,repeat_values):
        (+*this).fill(values,repeat_values);
    }

    //! Fill pixel values along the X-axis at a specified pixel position.
    /**
       \param y Y-coordinate of the filled column.
       \param z Z-coordinate of the filled column.
       \param c C-coordinate of the filled column.
       \param a0 First fill value.
    **/
    CImg<T>& fillX(const unsigned int y, const unsigned int z, const unsigned int c, const int a0, ...) {
#define _cimg_fill1(x,y,z,c,off,siz,t) { \
    va_list ap; va_start(ap,a0); T *ptrd = data(x,y,z,c); *ptrd = (T)a0; \
    for (unsigned int k = 1; k<siz; ++k) { ptrd+=off; *ptrd = (T)va_arg(ap,t); } \
    va_end(ap); }
      if (y<_height && z<_depth && c<_spectrum) _cimg_fill1(0,y,z,c,1,_width,int);
      return *this;
    }

    //! Fill pixel values along the X-axis at a specified pixel position \overload.
    CImg<T>& fillX(const unsigned int y, const unsigned int z, const unsigned int c, const double a0, ...) {
      if (y<_height && z<_depth && c<_spectrum) _cimg_fill1(0,y,z,c,1,_width,double);
      return *this;
    }

    //! Fill pixel values along the Y-axis at a specified pixel position.
    /**
       \param x X-coordinate of the filled row.
       \param z Z-coordinate of the filled row.
       \param c C-coordinate of the filled row.
       \param a0 First fill value.
    **/
    CImg<T>& fillY(const unsigned int x, const unsigned int z, const unsigned int c, const int a0, ...) {
      if (x<_width && z<_depth && c<_spectrum) _cimg_fill1(x,0,z,c,_width,_height,int);
      return *this;
    }

    //! Fill pixel values along the Y-axis at a specified pixel position \overload.
    CImg<T>& fillY(const unsigned int x, const unsigned int z, const unsigned int c, const double a0, ...) {
      if (x<_width && z<_depth && c<_spectrum) _cimg_fill1(x,0,z,c,_width,_height,double);
      return *this;
    }

    //! Fill pixel values along the Z-axis at a specified pixel position.
    /**
       \param x X-coordinate of the filled slice.
       \param y Y-coordinate of the filled slice.
       \param c C-coordinate of the filled slice.
       \param a0 First fill value.
    **/
    CImg<T>& fillZ(const unsigned int x, const unsigned int y, const unsigned int c, const int a0, ...) {
      const ulongT wh = (ulongT)_width*_height;
      if (x<_width && y<_height && c<_spectrum) _cimg_fill1(x,y,0,c,wh,_depth,int);
      return *this;
    }

    //! Fill pixel values along the Z-axis at a specified pixel position \overload.
    CImg<T>& fillZ(const unsigned int x, const unsigned int y, const unsigned int c, const double a0, ...) {
      const ulongT wh = (ulongT)_width*_height;
      if (x<_width && y<_height && c<_spectrum) _cimg_fill1(x,y,0,c,wh,_depth,double);
      return *this;
    }

    //! Fill pixel values along the C-axis at a specified pixel position.
    /**
       \param x X-coordinate of the filled channel.
       \param y Y-coordinate of the filled channel.
       \param z Z-coordinate of the filled channel.
       \param a0 First filling value.
    **/
    CImg<T>& fillC(const unsigned int x, const unsigned int y, const unsigned int z, const int a0, ...) {
      const ulongT whd = (ulongT)_width*_height*_depth;
      if (x<_width && y<_height && z<_depth) _cimg_fill1(x,y,z,0,whd,_spectrum,int);
      return *this;
    }

    //! Fill pixel values along the C-axis at a specified pixel position \overload.
    CImg<T>& fillC(const unsigned int x, const unsigned int y, const unsigned int z, const double a0, ...) {
      const ulongT whd = (ulongT)_width*_height*_depth;
      if (x<_width && y<_height && z<_depth) _cimg_fill1(x,y,z,0,whd,_spectrum,double);
      return *this;
    }

    //! Discard specified sequence of values in the image buffer, along a specific axis.
    /**
       \param values Sequence of values to discard.
       \param axis Axis along which the values are discarded. If set to \c 0 (default value)
         the function does it for all the buffer values and returns a one-column vector.
       \note Discarded values will change the image geometry, so the resulting image
         is returned as a one-column vector.
    **/
    template<typename t>
    CImg<T>& discard(const CImg<t>& values, const char axis=0) {
      if (is_empty() || !values) return *this;
      return get_discard(values,axis).move_to(*this);
    }

    template<typename t>
    CImg<T> get_discard(const CImg<t>& values, const char axis=0) const {
      if (!values) return +*this;
      CImg<T> res;
      if (is_empty()) return res;
      const ulongT vsiz = values.size();
      const char _axis = cimg::lowercase(axis);
      ulongT j = 0;
      unsigned int k = 0;
      int i0 = 0;
      res.assign(width(),height(),depth(),spectrum());
      switch (_axis) {
      case 'x' : {
        cimg_forX(*this,i) {
          if ((*this)(i)!=(T)values[j]) {
            if (j) --i;
            res.draw_image(k,get_columns(i0,i));
            k+=i - i0 + 1; i0 = i + 1; j = 0;
          } else { ++j; if (j>=vsiz) { j = 0; i0 = i + 1; } }
        }
        if (i0<width()) { res.draw_image(k,get_columns(i0,width() - 1)); k+=width() - i0; }
        res.resize(k,-100,-100,-100,0);
      } break;
      case 'y' : {
        cimg_forY(*this,i) {
          if ((*this)(0,i)!=(T)values[j]) {
            if (j) --i;
            res.draw_image(0,k,get_rows(i0,i));
            k+=i - i0 + 1; i0 = i + 1; j = 0;
          } else { ++j; if (j>=vsiz) { j = 0; i0 = i + 1; } }
        }
        if (i0<height()) { res.draw_image(0,k,get_rows(i0,height() - 1)); k+=height() - i0; }
        res.resize(-100,k,-100,-100,0);
      } break;
      case 'z' : {
        cimg_forZ(*this,i) {
          if ((*this)(0,0,i)!=(T)values[j]) {
            if (j) --i;
            res.draw_image(0,0,k,get_slices(i0,i));
            k+=i - i0 + 1; i0 = i + 1; j = 0;
          } else { ++j; if (j>=vsiz) { j = 0; i0 = i + 1; } }
        }
        if (i0<depth()) { res.draw_image(0,0,k,get_slices(i0,height() - 1)); k+=depth() - i0; }
        res.resize(-100,-100,k,-100,0);
      } break;
      case 'c' : {
        cimg_forC(*this,i) {
          if ((*this)(0,0,0,i)!=(T)values[j]) {
            if (j) --i;
            res.draw_image(0,0,0,k,get_channels(i0,i));
            k+=i - i0 + 1; i0 = i + 1; j = 0;
          } else { ++j; if (j>=vsiz) { j = 0; i0 = i + 1; } }
        }
        if (i0<spectrum()) { res.draw_image(0,0,k,get_channels(i0,height() - 1)); k+=spectrum() - i0; }
        res.resize(-100,-100,-100,k,0);
      } break;
      default : {
        const ulongT siz = size();
        res.unroll('y');
        if (vsiz==1) { // Optimized version for a single discard value
          const T val = (T)values[0];
          cimg_foroff(*this,i) {
            const T _val = (T)_data[i];
            if (_val!=val) res[k++] = _val;
          }
        } else { // Generic version
          cimg_foroff(*this,i) {
            if ((*this)[i]!=(T)values[j]) {
              if (j) --i;
              std::memcpy(res._data + k,_data + i0,(i - i0 + 1)*sizeof(T));
              k+=i - i0 + 1; i0 = (int)i + 1; j = 0;
            } else { ++j; if (j>=vsiz) { j = 0; i0 = (int)i + 1; }}
          }
          if ((ulongT)i0<siz) { std::memcpy(res._data + k,_data + i0,(siz - i0)*sizeof(T)); k+=siz - i0; }
        }
        res.resize(1,k,1,1,0);
      }
      }
      return res;
    }

    //! Discard neighboring duplicates in the image buffer, along the specified axis.
    CImg<T>& discard(const char axis=0) {
      return get_discard(axis).move_to(*this);
    }

    //! Discard neighboring duplicates in the image buffer, along the specified axis \newinstance.
    CImg<T> get_discard(const char axis=0) const {
      CImg<T> res;
      if (is_empty()) return res;
      const char _axis = cimg::lowercase(axis);
      T current = *_data?(T)0:(T)1;
      int j = 0;
      res.assign(width(),height(),depth(),spectrum());
      switch (_axis) {
      case 'x' : {
        cimg_forX(*this,i)
          if ((*this)(i)!=current) { res.draw_image(j++,get_column(i)); current = (*this)(i); }
        res.resize(j,-100,-100,-100,0);
      } break;
      case 'y' : {
        cimg_forY(*this,i)
          if ((*this)(0,i)!=current) { res.draw_image(0,j++,get_row(i)); current = (*this)(0,i); }
        res.resize(-100,j,-100,-100,0);
      } break;
      case 'z' : {
        cimg_forZ(*this,i)
          if ((*this)(0,0,i)!=current) { res.draw_image(0,0,j++,get_slice(i)); current = (*this)(0,0,i); }
        res.resize(-100,-100,j,-100,0);
      } break;
      case 'c' : {
        cimg_forC(*this,i)
          if ((*this)(0,0,0,i)!=current) { res.draw_image(0,0,0,j++,get_channel(i)); current = (*this)(0,0,0,i); }
        res.resize(-100,-100,-100,j,0);
      } break;
      default : {
        res.unroll('y');
        cimg_foroff(*this,i) {
          const T val = (*this)[i];
          if (val!=current) res[j++] = current = val;
        }
        res.resize(-100,j,-100,-100,0);
      }
      }
      return res;
    }

    //! Invert endianness of all pixel values.
    /**
     **/
    CImg<T>& invert_endianness() {
      cimg::invert_endianness(_data,size());
      return *this;
    }

    //! Invert endianness of all pixel values \newinstance.
    CImg<T> get_invert_endianness() const {
      return (+*this).invert_endianness();
    }

    //! Fill image with random values in specified range.
    /**
       \param val_min Minimal authorized random value.
       \param val_max Maximal authorized random value.
       \note Random variables are uniformly distributed in [val_min,val_max].
     **/
    CImg<T>& rand(const T& val_min, const T& val_max) {
      const float delta = (float)val_max - (float)val_min + (cimg::type<T>::is_float()?0:1);
      if (cimg::type<T>::is_float()) cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),524288)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) _data[off] = (T)(val_min + delta*cimg::rand(1,&rng));
          cimg::srand(rng);
        } else cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),524288)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) _data[off] = std::min(val_max,(T)(val_min + delta*cimg::rand(1,&rng)));
          cimg::srand(rng);
        }
      return *this;
    }

    //! Fill image with random values in specified range \newinstance.
    CImg<T> get_rand(const T& val_min, const T& val_max) const {
      return (+*this).rand(val_min,val_max);
    }

    //! Fill image with random values following specified distribution and range.
    /**
       \param val_min Minimal authorized random value.
       \param val_max Maximal authorized random value.
       \param pdf Probability density function.
       \param precision Precision of generated values. Set to '0' for automatic precision.
         A negative value means 'percentage of the pdf size'.
     **/
    template<typename t>
    CImg<T>& rand(const T& val_min, const T& val_max, const CImg<t>& pdf, const int precision=65536) {
      typedef _cimg_tfloat tfloat;
      const unsigned int
        siz = (unsigned int)pdf.size(),
        prec = precision<0?(unsigned int)(-(float)siz*precision/100):(unsigned int)precision;
      if (siz<2 || precision<2) return fill(val_min);
      const tfloat
        delta = (tfloat)val_max - (tfloat)val_min,
        delta_over_siz1 = delta/(siz - 1);

      // Compute inverse cdf.
      CImg<tfloat> cdf = pdf.get_max((t)0).cumulate(), icdf(prec);
      unsigned int k = 0;
      tfloat p = 0;
      cdf*=(prec - 1)/cdf.back();
      cimg_forX(icdf,x) {
        while (k<siz && (!(p = cdf[k]) || p<x)) ++k;
        if (k>=siz) { while (x<icdf.width()) icdf[x++] = val_max; break; }
        icdf[x] = val_min + k*delta_over_siz1;
      }

      // Generate random numbers.
      cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),524288)) {
        cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
        rng+=omp_get_thread_num();
#endif
        cimg_pragma_openmp(for)
        cimg_rofoff(*this,off) {
          const unsigned int
            _ind = (unsigned int)cimg::rand(0,(double)prec,&rng),
            ind = _ind==prec?0:_ind;
          _data[off] = (T)icdf[ind];
        }
        cimg::srand(rng);
      }
      return *this;
    }

    //! Fill image with random values following specified distribution and range \newinstance.
    template<typename t>
    CImg<T> get_rand(const T& val_min, const T& val_max, const CImg<t>& pdf, const int precision=65536) const {
      return (+*this).rand(val_min,val_max,pdf,precision);
    }

    //! Round pixel values.
    /**
       \param y Rounding precision.
       \param rounding_type Rounding type. Can be:
       - \c -1: Backward.
       - \c 0: Nearest.
       - \c 1: Forward.
    **/
    CImg<T>& round(const double y=1, const int rounding_type=0) {
      if (y>0) cimg_openmp_for(*this,cimg::round(*ptr,y,rounding_type),8192,T);
      return *this;
    }

    //! Round pixel values \newinstance.
    CImg<T> get_round(const double y=1, const unsigned int rounding_type=0) const {
      return (+*this).round(y,rounding_type);
    }

    //! Add random noise to pixel values.
    /**
       \param amplitude Amplitude of the random additive noise. If \p sigma<0, it stands for a percentage of the
         global value range.
       \param noise_type Type of additive noise (can be \p 0=gaussian, \p 1=uniform, \p 2=Salt and Pepper,
         \p 3=Poisson or \p 4=Rician).
       \return A reference to the modified image instance.
       \note
       - For Poisson noise (\p noise_type=3), parameter \p sigma is ignored, as Poisson noise only depends on
         the image value itself.
       - Function \p CImg<T>::get_noise() is also defined. It returns a non-shared modified copy of the image instance.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_noise(40);
       (img,res.normalize(0,255)).display();
       \endcode
       \image html ref_noise.jpg
    **/
    CImg<T>& noise(const double amplitude, const unsigned int noise_type=0) {
      if (is_empty()) return *this;
      const Tfloat vmin = (Tfloat)cimg::type<T>::min(), vmax = (Tfloat)cimg::type<T>::max();
      Tfloat namplitude = (Tfloat)amplitude, m = 0, M = 0;
      if (namplitude==0 && noise_type!=3) return *this;
      if (namplitude<0 || noise_type==2) m = (Tfloat)min_max(M);
      if (namplitude<0) namplitude = (Tfloat)(-namplitude*(M-m)/100.);
      switch (noise_type) {
      case 0 : { // Gaussian noise
        cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),131072)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) {
            Tfloat val = (Tfloat)(_data[off] + namplitude*cimg::grand(&rng));
            if (val>vmax) val = vmax;
            if (val<vmin) val = vmin;
            _data[off] = (T)val;
          }
          cimg::srand(rng);
        }
      } break;
      case 1 : { // Uniform noise
        cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),131072)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) {
            Tfloat val = (Tfloat)(_data[off] + namplitude*cimg::rand(-1,1,&rng));
            if (val>vmax) val = vmax;
            if (val<vmin) val = vmin;
            _data[off] = (T)val;
          }
          cimg::srand(rng);
        }
      } break;
      case 2 : { // Salt & Pepper noise
        if (namplitude<0) namplitude = -namplitude;
        if (M==m) {
          if (cimg::type<T>::is_float()) { --m; ++M; }
          else { m = (Tfloat)cimg::type<T>::min(); M = (Tfloat)cimg::type<T>::max(); }
        }
        cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),131072)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) if (cimg::rand(100,&rng)<namplitude) _data[off] = (T)(cimg::rand(1,&rng)<0.5?M:m);
          cimg::srand(rng);
          }
      } break;
      case 3 : { // Poisson Noise
        cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),131072)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) _data[off] = (T)cimg::prand(_data[off],&rng);
          cimg::srand(rng);
        }
      } break;
      case 4 : { // Rice noise
        const Tfloat sqrt2 = (Tfloat)std::sqrt(2.);
        cimg_pragma_openmp(parallel cimg_openmp_if_size(size(),131072)) {
          cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
          rng+=omp_get_thread_num();
#endif
          cimg_pragma_openmp(for)
          cimg_rofoff(*this,off) {
            const Tfloat
              val0 = (Tfloat)_data[off]/sqrt2,
              re = (Tfloat)(val0 + namplitude*cimg::grand(&rng)),
              im = (Tfloat)(val0 + namplitude*cimg::grand(&rng));
            Tfloat val = cimg::hypot(re,im);
            if (val>vmax) val = vmax;
            if (val<vmin) val = vmin;
            _data[off] = (T)val;
          }
          cimg::srand(rng);
        }
      } break;
      default :
        throw CImgArgumentException(_cimg_instance
                                    "noise(): Invalid specified noise type %d "
                                    "(should be { 0=gaussian | 1=uniform | 2=salt&Pepper | 3=poisson }).",
                                    cimg_instance,
                                    noise_type);
      }
      return *this;
    }

    //! Add random noise to pixel values \newinstance.
    CImg<T> get_noise(const double amplitude, const unsigned int noise_type=0) const {
      return (+*this).noise(amplitude,noise_type);
    }

    //! Linearly normalize pixel values.
    /**
       \param min_value Minimum desired value of the resulting image.
       \param max_value Maximum desired value of the resulting image.
       \param constant_case_ratio In case of instance image having a constant value, tell what ratio
              of [min_value,max_value] is used to fill the normalized image
              (=0 for min_value, =1 for max_value, =0.5 for (min_value + max_value)/2).
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_normalize(160,220);
       (img,res).display();
       \endcode
       \image html ref_normalize2.jpg
    **/
    CImg<T>& normalize(const T& min_value, const T& max_value,
                       const float constant_case_ratio=0) {
      if (is_empty()) return *this;
      const T a = min_value<max_value?min_value:max_value, b = min_value<max_value?max_value:min_value;
      T m, M = max_min(m);
      const Tfloat fm = (Tfloat)m, fM = (Tfloat)M;
      if (m==M)
        return fill(constant_case_ratio==0?a:
                    constant_case_ratio==1?b:
                    (T)((1 - constant_case_ratio)*a + constant_case_ratio*b));
      if (m!=a || M!=b) cimg_rof(*this,ptrd,T) *ptrd = (T)((*ptrd - fm)/(fM - fm)*(b - a) + a);
      return *this;
    }

    //! Linearly normalize pixel values \newinstance.
    CImg<Tfloat> get_normalize(const T& min_value, const T& max_value,
                               const float ratio_if_constant_image=0) const {
      return CImg<Tfloat>(*this,false).normalize((Tfloat)min_value,(Tfloat)max_value,ratio_if_constant_image);
    }

    //! Normalize multi-valued pixels of the image instance, with respect to their L2-norm.
    /**
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_normalize();
       (img,res.normalize(0,255)).display();
       \endcode
       \image html ref_normalize.jpg
    **/
    CImg<T>& normalize() {
      const ulongT whd = (ulongT)_width*_height*_depth;
      cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                 _height*_depth>=16))
      cimg_forYZ(*this,y,z) {
        T *ptrd = data(0,y,z,0);
        cimg_forX(*this,x) {
          const T *ptrs = ptrd;
          float n = 0;
          cimg_forC(*this,c) { n+=cimg::sqr((float)*ptrs); ptrs+=whd; }
          n = (float)std::sqrt(n);
          T *_ptrd = ptrd++;
          if (n>0) cimg_forC(*this,c) { *_ptrd = (T)(*_ptrd/n); _ptrd+=whd; }
          else cimg_forC(*this,c) { *_ptrd = (T)0; _ptrd+=whd; }
        }
      }
      return *this;
    }

    //! Normalize multi-valued pixels of the image instance, with respect to their L2-norm \newinstance.
    CImg<Tfloat> get_normalize() const {
      return CImg<Tfloat>(*this,false).normalize();
    }

    //! Compute Lp-norm of each multi-valued pixel of the image instance.
    /**
       \param norm_type Type of computed vector norm (can be \p -1=Linf, or \p greater or equal than 0).
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_norm();
       (img,res.normalize(0,255)).display();
       \endcode
       \image html ref_norm.jpg
    **/
    CImg<T>& norm(const int norm_type=2) {
      if (_spectrum==1 && norm_type) return abs();
      return get_norm(norm_type).move_to(*this);
    }

    //! Compute L2-norm of each multi-valued pixel of the image instance \newinstance.
    CImg<Tfloat> get_norm(const int norm_type=2) const {
      if (is_empty()) return *this;
      if (_spectrum==1 && norm_type) return get_abs();
      const ulongT whd = (ulongT)_width*_height*_depth;
      CImg<Tfloat> res(_width,_height,_depth);
      switch (norm_type) {
      case -1 : { // Linf-norm
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16))
        cimg_forYZ(*this,y,z) {
          const ulongT off = (ulongT)offset(0,y,z);
          const T *ptrs = _data + off;
          Tfloat *ptrd = res._data + off;
          cimg_forX(*this,x) {
            Tfloat n = 0;
            const T *_ptrs = ptrs++;
            cimg_forC(*this,c) { const Tfloat val = (Tfloat)cimg::abs(*_ptrs); if (val>n) n = val; _ptrs+=whd; }
            *(ptrd++) = n;
          }
        }
      } break;
      case 0 : { // L0-norm
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16))
        cimg_forYZ(*this,y,z) {
          const ulongT off = (ulongT)offset(0,y,z);
          const T *ptrs = _data + off;
          Tfloat *ptrd = res._data + off;
          cimg_forX(*this,x) {
            unsigned int n = 0;
            const T *_ptrs = ptrs++;
            cimg_forC(*this,c) { n+=*_ptrs==0?0:1; _ptrs+=whd; }
            *(ptrd++) = (Tfloat)n;
          }
        }
      } break;
      case 1 : { // L1-norm
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16))
        cimg_forYZ(*this,y,z) {
          const ulongT off = (ulongT)offset(0,y,z);
          const T *ptrs = _data + off;
          Tfloat *ptrd = res._data + off;
          cimg_forX(*this,x) {
            Tfloat n = 0;
            const T *_ptrs = ptrs++;
            cimg_forC(*this,c) { n+=cimg::abs(*_ptrs); _ptrs+=whd; }
            *(ptrd++) = n;
          }
        }
      } break;
      case 2 : { // L2-norm
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16))
        cimg_forYZ(*this,y,z) {
          const ulongT off = (ulongT)offset(0,y,z);
          const T *ptrs = _data + off;
          Tfloat *ptrd = res._data + off;
          cimg_forX(*this,x) {
            Tfloat n = 0;
            const T *_ptrs = ptrs++;
            cimg_forC(*this,c) { n+=cimg::sqr((Tfloat)*_ptrs); _ptrs+=whd; }
            *(ptrd++) = (Tfloat)std::sqrt((Tfloat)n);
          }
        }
      } break;
      default : { // Linf-norm
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16))
        cimg_forYZ(*this,y,z) {
          const ulongT off = (ulongT)offset(0,y,z);
          const T *ptrs = _data + off;
          Tfloat *ptrd = res._data + off;
          cimg_forX(*this,x) {
            Tfloat n = 0;
            const T *_ptrs = ptrs++;
            cimg_forC(*this,c) { n+=std::pow(cimg::abs((Tfloat)*_ptrs),(Tfloat)norm_type); _ptrs+=whd; }
            *(ptrd++) = (Tfloat)std::pow((Tfloat)n,1/(Tfloat)norm_type);
          }
        }
      }
      }
      return res;
    }

    //! Cut pixel values in specified range.
    /**
       \param min_value Minimum desired value of the resulting image.
       \param max_value Maximum desired value of the resulting image.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_cut(160,220);
       (img,res).display();
       \endcode
       \image html ref_cut.jpg
    **/
    CImg<T>& cut(const T& min_value, const T& max_value) {
      if (is_empty()) return *this;
      const T
        a = min_value<max_value?min_value:max_value,
        b = min_value<max_value?max_value:min_value;
      cimg_openmp_for(*this,cimg::cut(*ptr,a,b),32768,T);
      return *this;
    }

    //! Cut pixel values in specified range \newinstance.
    CImg<T> get_cut(const T& min_value, const T& max_value) const {
      return (+*this).cut(min_value,max_value);
    }

    //! Cut pixel absolute values in specified range.
    /**
       \param min_value Minimum desired absolute value of the resulting image.
       \param max_value Maximum desired absolute value of the resulting image.
       \param offset Offset applied to absolute value of the resulting image.
    **/
    CImg<T>& abscut(const T& min_value, const T& max_value, const T& offset) {
      if (is_empty()) return *this;
      const T
        a = min_value<max_value?min_value:max_value,
        b = min_value<max_value?max_value:min_value;
      cimg_openmp_for(*this,cimg::abscut(*ptr,a,b,offset),32768,T);
      return *this;
    }

    //! Cut pixel values in specified range \newinstance.
    CImg<T> get_abscut(const T& min_value, const T& max_value, const T& offset) const {
      return (+*this).abscut(min_value,max_value,offset);
    }

    //! Uniformly quantize pixel values.
    /**
       \param nb_levels Number of quantization levels.
       \param keep_range Indicates whether resulting values keep the same range as the original ones.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_quantize(4);
       (img,res).display();
       \endcode
       \image html ref_quantize.jpg
    **/
    CImg<T>& quantize(const unsigned int nb_levels, const bool keep_range=true) {
      if (!nb_levels)
        throw CImgArgumentException(_cimg_instance
                                    "quantize(): Invalid quantization request with 0 values.",
                                    cimg_instance);

      if (is_empty()) return *this;
      Tfloat m, M = (Tfloat)max_min(m), range = M - m;
      if (range>0) {
        if (keep_range)
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32768))
          cimg_rofoff(*this,off) {
            const unsigned int val = (unsigned int)((_data[off] - m)*nb_levels/range);
            _data[off] = (T)(m + std::min(val,nb_levels - 1)*range/nb_levels);
          } else
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32768))
          cimg_rofoff(*this,off) {
            const unsigned int val = (unsigned int)((_data[off] - m)*nb_levels/range);
            _data[off] = (T)std::min(val,nb_levels - 1);
          }
      }
      return *this;
    }

    //! Uniformly quantize pixel values \newinstance.
    CImg<T> get_quantize(const unsigned int n, const bool keep_range=true) const {
      return (+*this).quantize(n,keep_range);
    }

    //! Return the Otsu threshold.
    /**
       \param nb_levels Number of histogram levels used for the estimation.
    **/
    T otsu(const unsigned int nb_levels=256) const {
      T m,M = max_min(m);
      if (nb_levels<2) return (T)(((Tfloat)m + M)/2);
      CImg<ulongT> hist = get_histogram(nb_levels,m,M);
      ulongT sum = 0, sumB = 0, wB = 0;
      double best_variance = 0;
      unsigned int best_t = 0;
      cimg_forX(hist,t) sum+=t*hist[t];
      cimg_forX(hist,t) {
        wB+=hist[t];
        if (wB) {
          const ulongT wF = size() - wB;
          if (!wF) break;
          sumB+=t*hist[t];
          const double
            mB = (double)sumB/wB,
            mF = (double)(sum - sumB)/wF,
            variance = wB*wF*cimg::sqr(mB - mF);
          if (variance>best_variance) { best_variance = variance; best_t = t; }
        }
      }
      return m + best_t*(M - m)/(hist.width() - 1);
    }

    //! Threshold pixel values.
    /**
       \param value Threshold value
       \param soft_threshold Indicates whether soft thresholding must be applied (instead of hard one).
       \param strict_threshold Indicates whether threshold value is strict.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_threshold(128);
       (img,res.normalize(0,255)).display();
       \endcode
       \image html ref_threshold.jpg
    **/
    CImg<T>& threshold(const T& value, const bool soft_threshold=false, const bool strict_threshold=false) {
      if (is_empty()) return *this;
      if (strict_threshold) {
        if (soft_threshold)
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32768))
          cimg_rofoff(*this,off) {
            const T v = _data[off];
            _data[off] = v>value?(T)(v-value):v<-(float)value?(T)(v + value):(T)0;
          }
        else
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),65536))
          cimg_rofoff(*this,off) _data[off] = _data[off]>value?(T)1:(T)0;
      } else {
        if (soft_threshold)
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32768))
          cimg_rofoff(*this,off) {
            const T v = _data[off];
            _data[off] = v>=value?(T)(v-value):v<=-(float)value?(T)(v + value):(T)0;
          }
        else
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),65536))
          cimg_rofoff(*this,off) _data[off] = _data[off]>=value?(T)1:(T)0;
      }
      return *this;
    }

    //! Threshold pixel values \newinstance.
    CImg<T> get_threshold(const T& value, const bool soft_threshold=false, const bool strict_threshold=false) const {
      return (+*this).threshold(value,soft_threshold,strict_threshold);
    }

    //! Compute the histogram of pixel values.
    /**
       \param nb_levels Number of desired histogram levels.
       \param min_value Minimum pixel value considered for the histogram computation.
         All pixel values lower than \p min_value will not be counted.
       \param max_value Maximum pixel value considered for the histogram computation.
         All pixel values higher than \p max_value will not be counted.
       \note
       - The histogram H of an image I is the 1D function where H(x) counts the number of occurrences of the value x
         in the image I.
       - The resulting histogram is always defined in 1D. Histograms of multi-valued images are not multi-dimensional.
       \par Example
       \code
       const CImg<float> img = CImg<float>("reference.jpg").histogram(256);
       img.display_graph(0,3);
       \endcode
       \image html ref_histogram.jpg
    **/
    CImg<T>& histogram(const unsigned int nb_levels, const T& min_value, const T& max_value) {
      return get_histogram(nb_levels,min_value,max_value).move_to(*this);
    }

    //! Compute the histogram of pixel values \overload.
    CImg<T>& histogram(const unsigned int nb_levels) {
      return get_histogram(nb_levels).move_to(*this);
    }

    //! Compute the histogram of pixel values \newinstance.
    CImg<ulongT> get_histogram(const unsigned int nb_levels, const T& min_value, const T& max_value) const {
      if (!nb_levels || is_empty()) return CImg<ulongT>();
      const double
        vmin = (double)(min_value<max_value?min_value:max_value),
        vmax = (double)(min_value<max_value?max_value:min_value);
      CImg<ulongT> res(nb_levels,1,1,1,0);
      cimg_rof(*this,ptrs,T) {
        const T val = *ptrs;
        if (val>=vmin && val<=vmax) ++res[val==vmax?nb_levels - 1:(unsigned int)((val - vmin)*nb_levels/(vmax - vmin))];
      }
      return res;
    }

    //! Compute the histogram of pixel values \newinstance.
    CImg<ulongT> get_histogram(const unsigned int nb_levels) const {
      if (!nb_levels || is_empty()) return CImg<ulongT>();
      T vmax = 0, vmin = min_max(vmax);
      return get_histogram(nb_levels,vmin,vmax);
    }

    //! Equalize histogram of pixel values.
    /**
       \param nb_levels Number of histogram levels used for the equalization.
       \param min_value Minimum pixel value considered for the histogram computation.
         All pixel values lower than \p min_value will not be counted.
       \param max_value Maximum pixel value considered for the histogram computation.
         All pixel values higher than \p max_value will not be counted.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), res = img.get_equalize(256,0,255);
       (img,res).display();
       \endcode
       \image html ref_equalize.jpg
    **/
    CImg<T>& equalize(const unsigned int nb_levels, const T& min_value, const T& max_value) {
      if (!nb_levels || is_empty()) return *this;
      const T
        vmin = min_value<max_value?min_value:max_value,
        vmax = min_value<max_value?max_value:min_value;
      CImg<ulongT> hist = get_histogram(nb_levels,vmin,vmax);
      ulongT cumul = 0;
      cimg_forX(hist,pos) { cumul+=hist[pos]; hist[pos] = cumul; }
      if (!cumul) cumul = 1;
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),1048576))
      cimg_rofoff(*this,off) {
        const int pos = (int)((_data[off] - vmin)*(nb_levels - 1.)/(vmax - vmin));
        if (pos>=0 && pos<(int)nb_levels) _data[off] = (T)(vmin + (vmax - vmin)*hist[pos]/cumul);
      }
      return *this;
    }

    //! Equalize histogram of pixel values \overload.
    CImg<T>& equalize(const unsigned int nb_levels) {
      if (!nb_levels || is_empty()) return *this;
      T vmax = 0, vmin = min_max(vmax);
      return equalize(nb_levels,vmin,vmax);
    }

    //! Equalize histogram of pixel values \newinstance.
    CImg<T> get_equalize(const unsigned int nblevels, const T& val_min, const T& val_max) const {
      return (+*this).equalize(nblevels,val_min,val_max);
    }

    //! Equalize histogram of pixel values \newinstance.
    CImg<T> get_equalize(const unsigned int nblevels) const {
      return (+*this).equalize(nblevels);
    }

    //! Index multi-valued pixels regarding to a specified palette.
    /**
       \param colormap Multi-valued colormap used as the basis for multi-valued pixel indexing.
       \param dithering Level of dithering (0=disable, 1=standard level).
       \param map_colors Indicates whether the values of the resulting image are the colormap indices or the
                         colormap vectors.
       \note
       - \p img.index(colormap,dithering,1) is equivalent to <tt>img.index(colormap,dithering,0).map(colormap)</tt>.
       \par Example
       \code
       const CImg<float> img("reference.jpg"), colormap(3,1,1,3, 0,128,255, 0,128,255, 0,128,255);
       const CImg<float> res = img.get_index(colormap,1,true);
       (img,res).display();
       \endcode
       \image html ref_index.jpg
    **/
    template<typename t>
    CImg<T>& index(const CImg<t>& colormap, const float dithering=1, const bool map_colors=false) {
      return get_index(colormap,dithering,map_colors).move_to(*this);
    }

    //! Index multi-valued pixels regarding to a specified colormap \newinstance.
    template<typename t>
    CImg<typename CImg<t>::Tuint>
    get_index(const CImg<t>& colormap, const float dithering=1, const bool map_colors=true) const {
      if (colormap._spectrum!=_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "index(): Instance and specified colormap (%u,%u,%u,%u,%p) "
                                    "have incompatible dimensions.",
                                    cimg_instance,
                                    colormap._width,colormap._height,colormap._depth,colormap._spectrum,colormap._data);

      typedef typename CImg<t>::Tuint tuint;
      if (is_empty()) return CImg<tuint>();
      const ulongT
        whd = (ulongT)_width*_height*_depth,
        pwhd = (ulongT)colormap._width*colormap._height*colormap._depth;
      CImg<tuint> res(_width,_height,_depth,map_colors?_spectrum:1);
      if (dithering>0) { // Dithered versions
        tuint *ptrd = res._data;
        const float ndithering = cimg::cut(dithering,0.f,1.f)/16;
        Tfloat valm = 0, valM = (Tfloat)max_min(valm);
        if (valm==valM && valm>=0 && valM<=255) { valm = 0; valM = 255; }
        CImg<Tfloat> cache = get_crop(-1,0,0,0,_width,1,0,_spectrum - 1);
        Tfloat *cache_current = cache.data(1,0,0,0), *cache_next = cache.data(1,1,0,0);
        const ulongT cwhd = (ulongT)cache._width*cache._height*cache._depth;
        switch (_spectrum) {
        case 1 : { // Optimized for scalars
          cimg_forYZ(*this,y,z) {
            if (y<height() - 2) {
              Tfloat *ptrc0 = cache_next; const T *ptrs0 = data(0,y + 1,z,0);
              cimg_forX(*this,x) *(ptrc0++) = (Tfloat)*(ptrs0++);
            }
            Tfloat *ptrs0 = cache_current, *ptrsn0 = cache_next;
            cimg_forX(*this,x) {
              const Tfloat _val0 = (Tfloat)*ptrs0, val0 = _val0<valm?valm:_val0>valM?valM:_val0;
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp_end = ptrp0 + pwhd; ptrp0<ptrp_end; ) {
                const Tfloat pval0 = (Tfloat)*(ptrp0++) - val0, dist = pval0*pval0;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              const Tfloat err0 = ((*(ptrs0++)=val0) - (Tfloat)*ptrmin0)*ndithering;
              *ptrs0+=7*err0; *(ptrsn0 - 1)+=3*err0; *(ptrsn0++)+=5*err0; *ptrsn0+=err0;
              if (map_colors) *(ptrd++) = (tuint)*ptrmin0; else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
            cimg::swap(cache_current,cache_next);
          }
        } break;
        case 2 : { // Optimized for 2D vectors
          tuint *ptrd1 = ptrd + whd;
          cimg_forYZ(*this,y,z) {
            if (y<height() - 2) {
              Tfloat *ptrc0 = cache_next, *ptrc1 = ptrc0 + cwhd;
              const T *ptrs0 = data(0,y + 1,z,0), *ptrs1 = ptrs0 + whd;
              cimg_forX(*this,x) { *(ptrc0++) = (Tfloat)*(ptrs0++); *(ptrc1++) = (Tfloat)*(ptrs1++); }
            }
            Tfloat
              *ptrs0 = cache_current, *ptrs1 = ptrs0 + cwhd,
              *ptrsn0 = cache_next, *ptrsn1 = ptrsn0 + cwhd;
            cimg_forX(*this,x) {
              const Tfloat
                _val0 = (Tfloat)*ptrs0, val0 = _val0<valm?valm:_val0>valM?valM:_val0,
                _val1 = (Tfloat)*ptrs1, val1 = _val1<valm?valm:_val1>valM?valM:_val1;
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp1 = ptrp0 + pwhd, *ptrp_end = ptrp1; ptrp0<ptrp_end; ) {
                const Tfloat
                  pval0 = (Tfloat)*(ptrp0++) - val0, pval1 = (Tfloat)*(ptrp1++) - val1,
                  dist = pval0*pval0 + pval1*pval1;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              const t *const ptrmin1 = ptrmin0 + pwhd;
              const Tfloat
                err0 = ((*(ptrs0++)=val0) - (Tfloat)*ptrmin0)*ndithering,
                err1 = ((*(ptrs1++)=val1) - (Tfloat)*ptrmin1)*ndithering;
              *ptrs0+=7*err0; *ptrs1+=7*err1;
              *(ptrsn0 - 1)+=3*err0; *(ptrsn1 - 1)+=3*err1;
              *(ptrsn0++)+=5*err0; *(ptrsn1++)+=5*err1;
              *ptrsn0+=err0; *ptrsn1+=err1;
              if (map_colors) { *(ptrd++) = (tuint)*ptrmin0; *(ptrd1++) = (tuint)*ptrmin1; }
              else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
            cimg::swap(cache_current,cache_next);
          }
        } break;
        case 3 : { // Optimized for 3D vectors (colors)
          tuint *ptrd1 = ptrd + whd, *ptrd2 = ptrd1 + whd;
          cimg_forYZ(*this,y,z) {
            if (y<height() - 2) {
              Tfloat *ptrc0 = cache_next, *ptrc1 = ptrc0 + cwhd, *ptrc2 = ptrc1 + cwhd;
              const T *ptrs0 = data(0,y + 1,z,0), *ptrs1 = ptrs0 + whd, *ptrs2 = ptrs1 + whd;
              cimg_forX(*this,x) {
                *(ptrc0++) = (Tfloat)*(ptrs0++); *(ptrc1++) = (Tfloat)*(ptrs1++); *(ptrc2++) = (Tfloat)*(ptrs2++);
              }
            }
            Tfloat
              *ptrs0 = cache_current, *ptrs1 = ptrs0 + cwhd, *ptrs2 = ptrs1 + cwhd,
              *ptrsn0 = cache_next, *ptrsn1 = ptrsn0 + cwhd, *ptrsn2 = ptrsn1 + cwhd;
            cimg_forX(*this,x) {
              const Tfloat
                _val0 = (Tfloat)*ptrs0, val0 = _val0<valm?valm:_val0>valM?valM:_val0,
                _val1 = (Tfloat)*ptrs1, val1 = _val1<valm?valm:_val1>valM?valM:_val1,
                _val2 = (Tfloat)*ptrs2, val2 = _val2<valm?valm:_val2>valM?valM:_val2;
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp1 = ptrp0 + pwhd, *ptrp2 = ptrp1 + pwhd,
                     *ptrp_end = ptrp1; ptrp0<ptrp_end; ) {
                const Tfloat
                  pval0 = (Tfloat)*(ptrp0++) - val0,
                  pval1 = (Tfloat)*(ptrp1++) - val1,
                  pval2 = (Tfloat)*(ptrp2++) - val2,
                  dist = pval0*pval0 + pval1*pval1 + pval2*pval2;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              const t *const ptrmin1 = ptrmin0 + pwhd, *const ptrmin2 = ptrmin1 + pwhd;
              const Tfloat
                err0 = ((*(ptrs0++)=val0) - (Tfloat)*ptrmin0)*ndithering,
                err1 = ((*(ptrs1++)=val1) - (Tfloat)*ptrmin1)*ndithering,
                err2 = ((*(ptrs2++)=val2) - (Tfloat)*ptrmin2)*ndithering;

              *ptrs0+=7*err0; *ptrs1+=7*err1; *ptrs2+=7*err2;
              *(ptrsn0 - 1)+=3*err0; *(ptrsn1 - 1)+=3*err1; *(ptrsn2 - 1)+=3*err2;
              *(ptrsn0++)+=5*err0; *(ptrsn1++)+=5*err1; *(ptrsn2++)+=5*err2;
              *ptrsn0+=err0; *ptrsn1+=err1; *ptrsn2+=err2;

              if (map_colors) {
                *(ptrd++) = (tuint)*ptrmin0; *(ptrd1++) = (tuint)*ptrmin1; *(ptrd2++) = (tuint)*ptrmin2;
              } else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
            cimg::swap(cache_current,cache_next);
          }
        } break;
        default : // Generic version
          cimg_forYZ(*this,y,z) {
            if (y<height() - 2) {
              Tfloat *ptrc = cache_next;
              cimg_forC(*this,c) {
                Tfloat *_ptrc = ptrc; const T *_ptrs = data(0,y + 1,z,c);
                cimg_forX(*this,x) *(_ptrc++) = (Tfloat)*(_ptrs++);
                ptrc+=cwhd;
              }
            }
            Tfloat *ptrs = cache_current, *ptrsn = cache_next;
            cimg_forX(*this,x) {
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin = colormap._data;
              for (const t *ptrp = colormap._data, *ptrp_end = ptrp + pwhd; ptrp<ptrp_end; ++ptrp) {
                Tfloat dist = 0; Tfloat *_ptrs = ptrs; const t *_ptrp = ptrp;
                cimg_forC(*this,c) {
                  const Tfloat _val = *_ptrs, val = _val<valm?valm:_val>valM?valM:_val;
                  dist+=cimg::sqr((*_ptrs=val) - (Tfloat)*_ptrp); _ptrs+=cwhd; _ptrp+=pwhd;
                }
                if (dist<distmin) { ptrmin = ptrp; distmin = dist; }
              }
              const t *_ptrmin = ptrmin; Tfloat *_ptrs = ptrs++, *_ptrsn = (ptrsn++) - 1;
              cimg_forC(*this,c) {
                const Tfloat err = (*(_ptrs++) - (Tfloat)*_ptrmin)*ndithering;
                *_ptrs+=7*err; *(_ptrsn++)+=3*err; *(_ptrsn++)+=5*err; *_ptrsn+=err;
                _ptrmin+=pwhd; _ptrs+=cwhd - 1; _ptrsn+=cwhd - 2;
              }
              if (map_colors) {
                tuint *_ptrd = ptrd++;
                cimg_forC(*this,c) { *_ptrd = (tuint)*ptrmin; _ptrd+=whd; ptrmin+=pwhd; }
              }
              else *(ptrd++) = (tuint)(ptrmin - colormap._data);
            }
            cimg::swap(cache_current,cache_next);
          }
        }
      } else { // Non-dithered versions
        switch (_spectrum) {
        case 1 : { // Optimized for scalars
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64 &&
                                                                     _height*_depth>=16 && pwhd>=16))
          cimg_forYZ(*this,y,z) {
            tuint *ptrd = res.data(0,y,z);
            for (const T *ptrs0 = data(0,y,z), *ptrs_end = ptrs0 + _width; ptrs0<ptrs_end; ) {
              const Tfloat val0 = (Tfloat)*(ptrs0++);
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp_end = ptrp0 + pwhd; ptrp0<ptrp_end; ) {
                const Tfloat pval0 = (Tfloat)*(ptrp0++) - val0, dist = pval0*pval0;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              if (map_colors) *(ptrd++) = (tuint)*ptrmin0; else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
          }
        } break;
        case 2 : { // Optimized for 2D vectors
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64 &&
                                                                     _height*_depth>=16 && pwhd>=16))
          cimg_forYZ(*this,y,z) {
            tuint *ptrd = res.data(0,y,z), *ptrd1 = ptrd + whd;
            for (const T *ptrs0 = data(0,y,z), *ptrs1 = ptrs0 + whd, *ptrs_end = ptrs0 + _width; ptrs0<ptrs_end; ) {
              const Tfloat val0 = (Tfloat)*(ptrs0++), val1 = (Tfloat)*(ptrs1++);
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp1 = ptrp0 + pwhd, *ptrp_end = ptrp1; ptrp0<ptrp_end; ) {
                const Tfloat
                  pval0 = (Tfloat)*(ptrp0++) - val0, pval1 = (Tfloat)*(ptrp1++) - val1,
                  dist = pval0*pval0 + pval1*pval1;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              if (map_colors) { *(ptrd++) = (tuint)*ptrmin0; *(ptrd1++) = (tuint)*(ptrmin0 + pwhd); }
              else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
          }
        } break;
        case 3 : { // Optimized for 3D vectors (colors)
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64 &&
                                                                     _height*_depth>=16 && pwhd>=16))
          cimg_forYZ(*this,y,z) {
            tuint *ptrd = res.data(0,y,z), *ptrd1 = ptrd + whd, *ptrd2 = ptrd1 + whd;
            for (const T *ptrs0 = data(0,y,z), *ptrs1 = ptrs0 + whd, *ptrs2 = ptrs1 + whd,
                   *ptrs_end = ptrs0 + _width; ptrs0<ptrs_end; ) {
              const Tfloat val0 = (Tfloat)*(ptrs0++), val1 = (Tfloat)*(ptrs1++), val2 = (Tfloat)*(ptrs2++);
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin0 = colormap._data;
              for (const t *ptrp0 = colormap._data, *ptrp1 = ptrp0 + pwhd, *ptrp2 = ptrp1 + pwhd,
                     *ptrp_end = ptrp1; ptrp0<ptrp_end; ) {
                const Tfloat
                  pval0 = (Tfloat)*(ptrp0++) - val0,
                  pval1 = (Tfloat)*(ptrp1++) - val1,
                  pval2 = (Tfloat)*(ptrp2++) - val2,
                  dist = pval0*pval0 + pval1*pval1 + pval2*pval2;
                if (dist<distmin) { ptrmin0 = ptrp0 - 1; distmin = dist; }
              }
              if (map_colors) {
                *(ptrd++) = (tuint)*ptrmin0;
                *(ptrd1++) = (tuint)*(ptrmin0 + pwhd);
                *(ptrd2++) = (tuint)*(ptrmin0 + 2*pwhd);
              } else *(ptrd++) = (tuint)(ptrmin0 - colormap._data);
            }
          }
        } break;
        default : // Generic version
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64 &&
                                                                     _height*_depth>=16 && pwhd>=16))
          cimg_forYZ(*this,y,z) {
            tuint *ptrd = res.data(0,y,z);
            for (const T *ptrs = data(0,y,z), *ptrs_end = ptrs + _width; ptrs<ptrs_end; ++ptrs) {
              Tfloat distmin = cimg::type<Tfloat>::max(); const t *ptrmin = colormap._data;
              for (const t *ptrp = colormap._data, *ptrp_end = ptrp + pwhd; ptrp<ptrp_end; ++ptrp) {
                Tfloat dist = 0; const T *_ptrs = ptrs; const t *_ptrp = ptrp;
                cimg_forC(*this,c) { dist+=cimg::sqr((Tfloat)*_ptrs - (Tfloat)*_ptrp); _ptrs+=whd; _ptrp+=pwhd; }
                if (dist<distmin) { ptrmin = ptrp; distmin = dist; }
              }
              if (map_colors) {
                tuint *_ptrd = ptrd++;
                cimg_forC(*this,c) { *_ptrd = (tuint)*ptrmin; _ptrd+=whd; ptrmin+=pwhd; }
              }
              else *(ptrd++) = (tuint)(ptrmin - colormap._data);
            }
          }
        }
      }
      return res;
    }

    //! Map predefined palette on the scalar (indexed) image instance.
    /**
       \param palette Multi-valued palette used for mapping the indexes.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \par Example
       \code
       const CImg<float> img("reference.jpg"),
                         palette1(3,1,1,3, 0,128,255, 0,128,255, 0,128,255),
                         palette2(3,1,1,3, 255,0,0, 0,255,0, 0,0,255),
                         res = img.get_index(palette1,0).map(palette2);
       (img,res).display();
       \endcode
       \image html ref_map.jpg
    **/
    template<typename t>
    CImg<T>& map(const CImg<t>& palette, const unsigned int boundary_conditions=0) {
      return get_map(palette,boundary_conditions).move_to(*this);
    }

    //! Map predefined palette on the scalar (indexed) image instance \newinstance.
    template<typename t>
    CImg<t> get_map(const CImg<t>& palette, const unsigned int boundary_conditions=0) const {
      const ulongT
        whd = (ulongT)_width*_height*_depth, siz = size(),
        cwhd = (ulongT)palette._width*palette._height*palette._depth,
        cwhd2 = 2*cwhd;
      CImg<t> res(_width,_height,_depth,_spectrum*palette._spectrum);
      switch (palette._spectrum) {

      case 1 : { // Optimized for scalars
        switch (boundary_conditions) {
        case 3 : // Mirror
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
          for (longT off = 0; off<(longT)siz; ++off) {
            const ulongT ind = ((ulongT)_data[off])%cwhd2;
            res[off] = palette[ind<cwhd?ind:cwhd2 - ind - 1];
          }
          break;
        case 2 : // Periodic
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
          for (longT off = 0; off<(longT)siz; ++off) {
            const ulongT ind = (ulongT)_data[off];
            res[off] = palette[ind%cwhd];
          }
          break;
        case 1 : // Neumann
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
          for (longT off = 0; off<(longT)siz; ++off) {
            const longT ind = (longT)_data[off];
            res[off] = palette[cimg::cut(ind,(longT)0,(longT)cwhd - 1)];
          } break;
        default : // Dirichlet
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
          for (longT off = 0; off<(longT)siz; ++off) {
            const ulongT ind = (ulongT)_data[off];
            res[off] = ind<cwhd?palette[ind]:(t)0;
          }
        }
      } break;

      case 2 : { // Optimized for 2D vectors
        const t *const ptrp0 = palette._data, *const ptrp1 = ptrp0 + cwhd;
        switch (boundary_conditions) {
        case 3 : // Mirror
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,2*c), *const ptrd1 = ptrd0 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT
                _ind = ((ulongT)ptrs[off])%cwhd2,
                ind = _ind<cwhd?_ind:cwhd2 - _ind - 1;
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind];
            }
          } break;
        case 2 : // Periodic
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,2*c), *const ptrd1 = ptrd0 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = ((ulongT)ptrs[off])%cwhd;
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind];
            }
          } break;
        case 1 : // Neumann
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,2*c), *const ptrd1 = ptrd0 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const longT ind = cimg::cut((longT)ptrs[off],(longT)0,(longT)cwhd - 1);
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind];
            }
          } break;
        default : // Dirichlet
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,2*c), *const ptrd1 = ptrd0 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = (ulongT)ptrs[off];
              if (ind<cwhd) { ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind]; }
              else ptrd0[off] = ptrd1[off] = (t)0;
            }
          }
        }
      } break;

      case 3 : { // Optimized for 3D vectors (colors)
        const t *const ptrp0 = palette._data, *ptrp1 = ptrp0 + cwhd, *ptrp2 = ptrp0 + 2*cwhd;
        switch (boundary_conditions) {
        case 3 : // Mirror
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,3*c), *const ptrd1 = ptrd0 + whd, *const ptrd2 = ptrd1 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT
                _ind = ((ulongT)ptrs[off])%cwhd2,
                ind = _ind<cwhd?_ind:cwhd2 - _ind - 1;
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind]; ptrd2[off] = ptrp2[ind];
            }
          } break;
        case 2 : // Periodic
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,3*c), *const ptrd1 = ptrd0 + whd, *const ptrd2 = ptrd1 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = ((ulongT)ptrs[off])%cwhd;
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind]; ptrd2[off] = ptrp2[ind];
            }
          } break;
        case 1 : // Neumann
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,3*c), *const ptrd1 = ptrd0 + whd, *const ptrd2 = ptrd1 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const longT ind = cimg::cut((longT)ptrs[off],(longT)0,(longT)cwhd - 1);
              ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind]; ptrd2[off] = ptrp2[ind];
            }
          } break;
        default : // Dirichlet
          cimg_forC(*this,c) {
            t *const ptrd0 = res.data(0,0,0,3*c), *const ptrd1 = ptrd0 + whd, *const ptrd2 = ptrd1 + whd;
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = (ulongT)ptrs[off];
              if (ind<cwhd) { ptrd0[off] = ptrp0[ind]; ptrd1[off] = ptrp1[ind]; ptrd2[off] = ptrp2[ind]; }
              else ptrd0[off] = ptrd1[off] = ptrd2[off] = (t)0;
            }
          }
        }
      } break;

      default : { // Generic version
        switch (boundary_conditions) {
        case 3 : // Mirror
          cimg_forC(*this,c) {
            t *const ptrd = res.data(0,0,0,palette._spectrum*c);
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT
                _ind = ((ulongT)ptrs[off])%cwhd,
                ind = _ind<cwhd?_ind:cwhd2 - _ind - 1;
              t *const _ptrd = ptrd + off;
              const t *const ptrp = &palette[ind];
              cimg_forC(palette,k) _ptrd[k*whd] = ptrp[k*cwhd];
            }
          } break;
        case 2 : // Periodic
          cimg_forC(*this,c) {
            t *const ptrd = res.data(0,0,0,palette._spectrum*c);
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = ((ulongT)ptrs[off])%cwhd;
              t *const _ptrd = ptrd + off;
              const t *const ptrp = &palette[ind];
              cimg_forC(palette,k) _ptrd[k*whd] = ptrp[k*cwhd];
            }
          } break;
        case 1 : // Neumann
          cimg_forC(*this,c) {
            t *const ptrd = res.data(0,0,0,palette._spectrum*c);
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const longT ind = cimg::cut((longT)ptrs[off],(longT)0,(longT)cwhd - 1);
              t *const _ptrd = ptrd + off;
              const t *const ptrp = &palette[ind];
              cimg_forC(palette,k) _ptrd[k*whd] = ptrp[k*cwhd];
            }
          } break;
        default : // Dirichlet
          cimg_forC(*this,c) {
            t *const ptrd = res.data(0,0,0,palette._spectrum*c);
            const T *const ptrs = data(0,0,0,c);
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),256))
            for (longT off = 0; off<(longT)whd; ++off) {
              const ulongT ind = (ulongT)ptrs[off];
              t *const _ptrd = ptrd + off;
              if (ind<cwhd) {
                const t *const ptrp = &palette[ind];
                cimg_forC(palette,k) _ptrd[k*whd] = ptrp[k*cwhd];
              } else cimg_forC(palette,k) _ptrd[k*whd] = (t)0;
            }
          }
        }
      }
      }
      return res;
    }

    //! Label connected components.
    /**
       \param is_high_connectivity Indicates whether the algorithm uses low or high connectivity.
       \param tolerance Tolerance used to determine if two neighboring pixels belong to the same region.
       \param is_L2_norm If true, tolerance is compared against L2 difference, otherwise L1 is used.
       \note The algorithm of connected components computation has been primarily done
       by A. Meijster, according to the publication:
       'W.H. Hesselink, A. Meijster, C. Bron, "Concurrent Determination of Connected Components.",
       In: Science of Computer Programming 41 (2001), pp. 173--194'.
       The submitted code has then been modified to fit CImg coding style and constraints.
    **/
    CImg<T>& label(const bool is_high_connectivity=false, const Tfloat tolerance=0,
                   const bool is_L2_norm=true) {
      if (is_empty()) return *this;
      return get_label(is_high_connectivity,tolerance,is_L2_norm).move_to(*this);
    }

    //! Label connected components \newinstance.
    CImg<ulongT> get_label(const bool is_high_connectivity=false, const Tfloat tolerance=0,
                           const bool is_L2_norm=true) const {
      if (is_empty()) return CImg<ulongT>();

      // Create neighborhood tables.
      int dx[13], dy[13], dz[13], nb = 0;
      dx[nb] = 1; dy[nb] = 0; dz[nb++] = 0;
      dx[nb] = 0; dy[nb] = 1; dz[nb++] = 0;
      if (is_high_connectivity) {
        dx[nb] = 1; dy[nb] = 1; dz[nb++] = 0;
        dx[nb] = 1; dy[nb] = -1; dz[nb++] = 0;
      }
      if (_depth>1) { // 3D version
        dx[nb] = 0; dy[nb] = 0; dz[nb++]=1;
        if (is_high_connectivity) {
          dx[nb] = 1; dy[nb] = 1; dz[nb++] = -1;
          dx[nb] = 1; dy[nb] = 0; dz[nb++] = -1;
          dx[nb] = 1; dy[nb] = -1; dz[nb++] = -1;
          dx[nb] = 0; dy[nb] = 1; dz[nb++] = -1;

          dx[nb] = 0; dy[nb] = 1; dz[nb++] = 1;
          dx[nb] = 1; dy[nb] = -1; dz[nb++] = 1;
          dx[nb] = 1; dy[nb] = 0; dz[nb++] = 1;
          dx[nb] = 1; dy[nb] = 1; dz[nb++] = 1;
        }
      }
      return _label(nb,dx,dy,dz,tolerance,is_L2_norm);
    }

    //! Label connected components \inplace.
    /**
       \param connectivity_mask Mask of the neighboring pixels.
       \param tolerance Tolerance used to determine if two neighboring pixels belong to the same region.
       \param is_L2_norm If true, tolerance is compared against L2 difference, otherwise L1 is used.
    **/
    template<typename t>
    CImg<T>& label(const CImg<t>& connectivity_mask, const Tfloat tolerance=0,
                   const bool is_L2_norm=true) {
      if (is_empty()) return *this;
      return get_label(connectivity_mask,tolerance,is_L2_norm).move_to(*this);
    }

    //! Label connected components \newinstance.
    template<typename t>
    CImg<ulongT> get_label(const CImg<t>& connectivity_mask, const Tfloat tolerance=0,
                           const bool is_L2_norm=true) const {
      if (is_empty()) return CImg<ulongT>();
      int nb = 0;
      cimg_for(connectivity_mask,ptr,t) if (*ptr) ++nb;
      CImg<intT> dx(nb,1,1,1,0), dy(nb,1,1,1,0), dz(nb,1,1,1,0);
      nb = 0;
      cimg_forXYZ(connectivity_mask,x,y,z) if ((x || y || z) &&
                                               connectivity_mask(x,y,z)) {
        dx[nb] = x; dy[nb] = y; dz[nb++] = z;
      }
      return _label(nb,dx,dy,dz,tolerance,is_L2_norm);
    }

    CImg<ulongT> _label(const unsigned int nb, const int *const dx,
                        const int *const dy, const int *const dz,
                        const Tfloat tolerance, const bool is_L2_norm) const {
      CImg<ulongT> res(_width,_height,_depth);
      const Tfloat _tolerance = _spectrum>1 && is_L2_norm?cimg::sqr(tolerance):tolerance;

      // Init label numbers.
      ulongT *ptr = res.data();
      cimg_foroff(res,p) *(ptr++) = p;

      // For each neighbour-direction, label.
      for (unsigned int n = 0; n<nb; ++n) {
        const int _dx = dx[n], _dy = dy[n], _dz = dz[n];
        if (_dx || _dy || _dz) {
          const int
            x0 = _dx<0?-_dx:0,
            x1 = _dx<0?width():width() - _dx,
            y0 = _dy<0?-_dy:0,
            y1 = _dy<0?height():height() - _dy,
            z0 = _dz<0?-_dz:0,
            z1 = _dz<0?depth():depth() - _dz;
          const longT
            wh = (longT)width()*height(),
            whd = (longT)width()*height()*depth(),
            offset = _dz*wh + _dy*width() + _dx;
          for (longT z = z0, nz = z0 + _dz, pz = z0*wh; z<z1; ++z, ++nz, pz+=wh) {
            for (longT y = y0, ny = y0 + _dy, py = y0*width() + pz; y<y1; ++y, ++ny, py+=width()) {
              for (longT x = x0, nx = x0 + _dx, p = x0 + py; x<x1; ++x, ++nx, ++p) {
                Tfloat diff;
                switch (_spectrum) {
                case 1 :
                  diff = cimg::abs((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd));
                  break;
                case 2 :
                  if (is_L2_norm)
                    diff = cimg::sqr((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd));
                  else
                    diff = cimg::abs((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd));
                  break;
                case 3 :
                  if (is_L2_norm)
                    diff = cimg::sqr((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,2,wh,whd) - (Tfloat)(*this)(nx,ny,nz,2,wh,whd));
                  else
                    diff = cimg::abs((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,2,wh,whd) - (Tfloat)(*this)(nx,ny,nz,2,wh,whd));
                  break;
                case 4 :
                  if (is_L2_norm)
                    diff = cimg::sqr((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,2,wh,whd) - (Tfloat)(*this)(nx,ny,nz,2,wh,whd)) +
                      cimg::sqr((Tfloat)(*this)(x,y,z,3,wh,whd) - (Tfloat)(*this)(nx,ny,nz,3,wh,whd));
                  else
                    diff = cimg::abs((Tfloat)(*this)(x,y,z,0,wh,whd) - (Tfloat)(*this)(nx,ny,nz,0,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,1,wh,whd) - (Tfloat)(*this)(nx,ny,nz,1,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,2,wh,whd) - (Tfloat)(*this)(nx,ny,nz,2,wh,whd)) +
                      cimg::abs((Tfloat)(*this)(x,y,z,3,wh,whd) - (Tfloat)(*this)(nx,ny,nz,3,wh,whd));
                  break;
                default :
                  diff = 0;
                  if (is_L2_norm)
                    cimg_forC(*this,c)
                      diff+=cimg::sqr((Tfloat)(*this)(x,y,z,c,wh,whd) - (Tfloat)(*this)(nx,ny,nz,c,wh,whd));
                  else
                    cimg_forC(*this,c)
                      diff+=cimg::abs((Tfloat)(*this)(x,y,z,c,wh,whd) - (Tfloat)(*this)(nx,ny,nz,c,wh,whd));
                }

                if (diff<=_tolerance) {
                  const longT q = p + offset;
                  ulongT xk, yk;
                  for (xk = (ulongT)(p<q?q:p), yk = (ulongT)(p<q?p:q); xk!=yk && res[xk]!=xk; ) {
                    xk = res[xk]; if (xk<yk) cimg::swap(xk,yk);
                  }
                  if (xk!=yk) res[xk] = (ulongT)yk;
                  for (ulongT _p = (ulongT)p; _p!=yk; ) {
                    const ulongT h = res[_p];
                    res[_p] = (ulongT)yk;
                    _p = h;
                  }
                  for (ulongT _q = (ulongT)q; _q!=yk; ) {
                    const ulongT h = res[_q];
                    res[_q] = (ulongT)yk;
                    _q = h;
                  }
                }
              }
            }
          }
        }
      }

      // Resolve equivalences.
      ulongT counter = 0;
      ptr = res.data();
      cimg_foroff(res,p) { *ptr = *ptr==p?counter++:res[*ptr]; ++ptr; }
      return res;
    }

    // [internal] Replace possibly malicious characters for commands to be called by system() by their escaped version.
    CImg<T>& _system_strescape() {
#if cimg_OS==2 // Windows-specific security hardening
      cimg_for(*this,p,T) {
        const char c = (char)*p;
        switch (c) {
          case '\"': case '|': case '<': case '>':
          case '&':  case '^': case '%': case '!':
          case '\n': case '\r':
            throw CImgArgumentException("CImg<%s>::_system_strescape(): Detected illegal or malicious shell "
                                        "character '%c' in path/filename.",
                                        pixel_type(), c);
        default:
          break;
        }
      }
      return *this;
#else // Unix-style escaping
#define cimg_system_strescape(c,s) case c : if (p!=ptrs) CImg<T>(ptrs,(unsigned int)(p - ptrs),1,1,1,false). \
      move_to(list); \
      CImg<T>(s,(unsigned int)std::strlen(s),1,1,1,false).move_to(list); ptrs = p + 1; break

      CImgList<T> list;
      const T *ptrs = _data;
      cimg_for(*this,p,T) switch ((int)*p) {
        cimg_system_strescape('\\',"\\\\");
        cimg_system_strescape('\"',"\\\"");
        cimg_system_strescape('!',"\"\\!\"");
        cimg_system_strescape('`',"\\`");
        cimg_system_strescape('$',"\\$");
      }
      if (ptrs<end()) CImg<T>(ptrs,(unsigned int)(end() - ptrs),1,1,1,false).move_to(list);
      return (list>'x').move_to(*this);
#endif
    }

    //@}
    //---------------------------------
    //
    //! \name Color Base Management
    //@{
    //---------------------------------

    //! Return palette \e "default", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_default.jpg
    **/
    static const CImg<Tuchar>& default_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        palette.assign(1,256,1,3);
        for (unsigned int index = 0, r = 16; r<256; r+=32)
          for (unsigned int g = 16; g<256; g+=32)
            for (unsigned int b = 32; b<256; b+=64) {
              palette(0,index,0) = (Tuchar)r;
              palette(0,index,1) = (Tuchar)g;
              palette(0,index++,2) = (Tuchar)b;
            }
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "HSV", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_hsv.jpg
    **/
    static const CImg<Tuchar>& HSV_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        CImg<Tint> tmp(1,256,1,3,1);
        tmp.get_shared_channel(0).sequence(0,359);
        palette = tmp.HSVtoRGB();
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "lines", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_lines.jpg
    **/
    static const CImg<Tuchar>& lines_LUT256() {
      static const unsigned char pal[] = {
        0,255,255,0,0,28,125,125,235,210,186,182,36,0,125,255,
        53,32,255,210,89,186,65,45,125,210,210,97,130,194,0,125,
        206,53,190,89,255,146,20,190,154,73,255,36,130,215,0,138,
        101,210,61,194,206,0,77,45,255,154,174,0,190,239,89,125,
        16,36,158,223,117,0,97,69,223,255,40,239,0,0,255,0,
        97,170,93,255,138,40,117,210,0,170,53,158,186,255,0,121,
        227,121,186,40,20,190,89,255,77,57,130,142,255,73,186,85,
        210,8,32,166,243,130,210,40,255,45,61,142,223,49,121,255,
        20,162,158,73,89,255,53,138,210,190,57,235,36,73,255,49,
        210,0,210,85,57,97,255,121,85,174,40,255,162,178,0,121,
        166,125,53,146,166,255,97,121,65,89,235,231,12,170,36,190,
        85,255,166,97,198,77,20,146,109,166,255,28,40,202,121,81,
        247,0,210,255,49,0,65,255,36,166,93,77,255,85,251,0,
        170,178,0,182,255,0,162,16,154,142,162,223,223,0,0,81,
        215,4,215,162,215,125,77,206,121,36,125,231,101,16,255,121,
        0,57,190,215,65,125,89,142,255,101,73,53,146,223,125,125,
        0,255,0,255,0,206,93,138,49,255,0,202,154,85,45,219,
        251,53,0,255,40,130,219,158,16,117,186,130,202,49,65,239,
        89,202,49,28,247,134,150,0,255,117,202,4,215,81,186,57,
        202,89,73,210,40,93,45,251,206,28,223,142,40,134,162,125,
        32,247,97,170,0,255,57,134,73,247,162,0,251,40,142,142,
        8,166,206,81,154,194,93,89,125,243,28,109,227,0,190,65,
        194,186,0,255,53,45,109,186,186,0,255,130,49,170,69,210,
        154,0,109,227,45,255,125,105,81,81,255,0,219,134,170,85,
        146,28,170,89,223,97,8,210,255,158,49,40,125,174,174,125,
        0,227,166,28,219,130,0,93,239,0,85,255,81,178,125,49,
        89,255,53,206,73,113,146,255,0,150,36,219,162,0,210,125,
        69,134,255,85,40,89,235,49,215,121,0,206,36,223,174,69,
        40,182,178,130,69,45,255,210,85,77,215,0,231,146,0,194,
        125,174,0,255,40,89,121,206,57,0,206,170,231,150,81,0,
        125,255,4,174,4,190,121,255,4,166,109,130,49,239,170,93,
        16,174,210,0,255,16,105,158,93,255,0,125,0,255,158,85,
        0,255,0,0,255,170,166,61,121,28,198,215,45,243,61,97,
        255,53,81,130,109,255,8,117,235,121,40,178,174,0,182,49,
        162,121,255,69,206,0,219,125,0,101,255,239,121,32,210,130,
        36,231,32,125,81,142,215,158,4,178,255,0,40,251,125,125,
        219,89,130,0,166,255,24,65,194,125,255,125,77,125,93,125,
        202,24,138,174,178,32,255,85,194,40,85,36,174,174,125,210,
        85,255,53,16,93,206,40,130,170,202,93,255,0,24,117,255,
        97,113,105,81,255,186,194,57,69,206,57,53,223,190,4,255,
        85,97,130,255,85,0,125,223,85,219,0,215,146,77,40,239,
        89,36,142,154,227,0,255,85,162,0,162,0,235,178,45,166,
        0,247,255,20,69,210,89,142,53,255,40,146,166,255,69,0,
        174,154,142,130,162,0,215,255,0,89,40,255,166,61,146,69,
        162,40,255,32,121,255,117,178,0,186,206,0,57,215,215,81,
        158,77,166,210,77,89,210,0,24,202,150,186,0,255,20,97,
        57,170,235,251,16,73,142,251,93,0,202,0,255,121,219,4,
        73,219,8,162,206,16,219,93,117,0,255,8,130,174,223,45 };
      static const CImg<Tuchar> palette(pal,1,256,1,3,false);
      return palette;
    }

    //! Return palette \e "hot", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_hot.jpg
    **/
    static const CImg<Tuchar>& hot_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        palette.assign(1,4,1,3,(T)0);
        palette[1] = palette[2] = palette[3] = palette[6] = palette[7] = palette[11] = 255;
        palette.resize(1,256,1,3,3);
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "cool", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_cool.jpg
    **/
    static const CImg<Tuchar>& cool_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) palette.assign(1,2,1,3).fill((T)0,(T)255,(T)255,(T)0,(T)255,(T)255).resize(1,256,1,3,3);
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "jet", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_jet.jpg
    **/
    static const CImg<Tuchar>& jet_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        palette.assign(1,4,1,3,(T)0);
        palette[2] = palette[3] = palette[5] = palette[6] = palette[8] = palette[9] = 255;
        palette.resize(1,256,1,3,3);
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "flag", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 colormap is returned:
       \image html ref_colormap_flag.jpg
    **/
    static const CImg<Tuchar>& flag_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        palette.assign(1,4,1,3,(T)0);
        palette[0] = palette[1] = palette[5] = palette[9] = palette[10] = 255;
        palette.resize(1,256,1,3,0,2);
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Return palette \e "cube", containing 256 colors entries in RGB.
    /**
       \return The following \c 256x1x1x3 palette is returned:
       \image html ref_colormap_cube.jpg
    **/
    static const CImg<Tuchar>& cube_LUT256() {
      static CImg<Tuchar> palette;
      cimg::mutex(8);
      if (!palette) {
        palette.assign(1,8,1,3,(T)0);
        palette[1] = palette[3] = palette[5] = palette[7] =
          palette[10] = palette[11] = palette[12] = palette[13] =
          palette[20] = palette[21] = palette[22] = palette[23] = 255;
        palette.resize(1,256,1,3,3);
      }
      cimg::mutex(8,0);
      return palette;
    }

    //! Convert pixel values from sRGB to RGB color spaces.
    CImg<T>& sRGBtoRGB() {
      if (is_empty()) return *this;
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32))
      cimg_rofoff(*this,off) {
        const Tfloat
          sval = (Tfloat)_data[off]/255,
          val = (Tfloat)(sval<=0.04045f?sval/12.92f:std::pow((sval + 0.055f)/(1.055f),2.4f));
        _data[off] = (T)cimg::cut(val*255,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from sRGB to RGB color spaces \newinstance.
    CImg<Tfloat> get_sRGBtoRGB() const {
      return CImg<Tfloat>(*this,false).sRGBtoRGB();
    }

    //! Convert pixel values from RGB to sRGB color spaces.
    CImg<T>& RGBtosRGB() {
      if (is_empty()) return *this;
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(size(),32))
      cimg_rofoff(*this,off) {
        const Tfloat
          val = (Tfloat)_data[off]/255,
          sval = (Tfloat)(val<=0.0031308f?val*12.92f:1.055f*std::pow(val,0.416667f) - 0.055f);
        _data[off] = (T)cimg::cut(sval*255,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from RGB to sRGB color spaces \newinstance.
    CImg<Tfloat> get_RGBtosRGB() const {
      return CImg<Tfloat>(*this,false).RGBtosRGB();
    }

    //! Convert pixel values from RGB to HSI color spaces.
    CImg<T>& RGBtoHSI() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoHSI(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N],
          G = (Tfloat)p2[N],
          B = (Tfloat)p3[N],
          m = cimg::min(R,G,B),
          M = cimg::max(R,G,B),
          C = M - m,
          sum = R + G + B,
          H = 60*(C==0?0:M==R?cimg::mod((G - B)/C,(Tfloat)6):M==G?(B - R)/C + 2:(R - G)/C + 4),
          S = sum<=0?0:1 - 3*m/sum,
          I = sum/(3*255);
        p1[N] = (T)H;
        p2[N] = (T)S;
        p3[N] = (T)I;
      }
      return *this;
    }

    //! Convert pixel values from RGB to HSI color spaces \newinstance.
    CImg<Tfloat> get_RGBtoHSI() const {
      return CImg<Tfloat>(*this,false).RGBtoHSI();
    }

    //! Convert pixel values from HSI to RGB color spaces.
    CImg<T>& HSItoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "HSItoRGB(): Instance is not a HSI image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          H = cimg::mod((Tfloat)p1[N]/60,(Tfloat)6),
          S = (Tfloat)p2[N],
          I = (Tfloat)p3[N],
          Z = 1 - cimg::abs(cimg::mod(H,(Tfloat)2) - 1),
          C = I*S/(1 + Z),
          X = C*Z,
          m = I*(1 - S)/3;
        Tfloat R, G, B;
        switch ((int)H) {
        case 0 : R = C; G = X; B = 0; break;
        case 1 : R = X; G = C; B = 0; break;
        case 2 : R = 0; G = C; B = X; break;
        case 3 : R = 0; G = X; B = C; break;
        case 4 : R = X; G = 0; B = C; break;
        default : R = C; G = 0; B = X;
        }
        p1[N] = (T)((R + m)*3*255);
        p2[N] = (T)((G + m)*3*255);
        p3[N] = (T)((B + m)*3*255);
      }
      return *this;
    }

    //! Convert pixel values from HSI to RGB color spaces \newinstance.
    CImg<Tfloat> get_HSItoRGB() const {
      return CImg<Tuchar>(*this,false).HSItoRGB();
    }

    //! Convert pixel values from RGB to HSL color spaces.
    CImg<T>& RGBtoHSL() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoHSL(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N],
          G = (Tfloat)p2[N],
          B = (Tfloat)p3[N],
          m = cimg::min(R,G,B),
          M = cimg::max(R,G,B),
          C = M - m,
          H = 60*(C==0?0:M==R?cimg::mod((G - B)/C,(Tfloat)6):M==G?(B - R)/C + 2:(R - G)/C + 4),
          L = 0.5f*(m + M)/255,
          S = L==1 || L==0?0:C/(1 - cimg::abs(2*L - 1))/255;
        p1[N] = (T)H;
        p2[N] = (T)S;
        p3[N] = (T)L;
      }
      return *this;
    }

    //! Convert pixel values from RGB to HSL color spaces \newinstance.
    CImg<Tfloat> get_RGBtoHSL() const {
      return CImg<Tfloat>(*this,false).RGBtoHSL();
    }

    //! Convert pixel values from HSL to RGB color spaces.
    CImg<T>& HSLtoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "HSLtoRGB(): Instance is not a HSL image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          H = cimg::mod((Tfloat)p1[N]/60,(Tfloat)6),
          S = (Tfloat)p2[N],
          L = (Tfloat)p3[N],
          C = (1 - cimg::abs(2*L - 1))*S,
          X = C*(1 - cimg::abs(cimg::mod(H,(Tfloat)2) - 1)),
          m = L - C/2;
        Tfloat R, G, B;
        switch ((int)H) {
        case 0 : R = C; G = X; B = 0; break;
        case 1 : R = X; G = C; B = 0; break;
        case 2 : R = 0; G = C; B = X; break;
        case 3 : R = 0; G = X; B = C; break;
        case 4 : R = X; G = 0; B = C; break;
        default : R = C; G = 0; B = X;
        }
        p1[N] = (T)((R + m)*255);
        p2[N] = (T)((G + m)*255);
        p3[N] = (T)((B + m)*255);
      }
      return *this;
    }

    //! Convert pixel values from HSL to RGB color spaces \newinstance.
    CImg<Tuchar> get_HSLtoRGB() const {
      return CImg<Tuchar>(*this,false).HSLtoRGB();
    }

    //! Convert pixel values from RGB to HSV color spaces.
    CImg<T>& RGBtoHSV() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoHSV(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N],
          G = (Tfloat)p2[N],
          B = (Tfloat)p3[N],
          M = cimg::max(R,G,B),
          C = M - cimg::min(R,G,B),
          H = 60*(C==0?0:M==R?cimg::mod((G-B)/C,(Tfloat)6):M==G?(B - R)/C + 2:(R - G)/C + 4),
          S = M<=0?0:C/M;
        p1[N] = (T)H;
        p2[N] = (T)S;
        p3[N] = (T)(M/255);
      }
      return *this;
    }

    //! Convert pixel values from RGB to HSV color spaces \newinstance.
    CImg<Tfloat> get_RGBtoHSV() const {
      return CImg<Tfloat>(*this,false).RGBtoHSV();
    }

    //! Convert pixel values from HSV to RGB color spaces.
    CImg<T>& HSVtoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "HSVtoRGB(): Instance is not a HSV image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,256))
      for (longT N = 0; N<whd; ++N) {
        Tfloat
          H = cimg::mod((Tfloat)p1[N]/60,(Tfloat)6),
          S = (Tfloat)p2[N],
          V = (Tfloat)p3[N],
          C = V*S,
          X = C*(1 - cimg::abs(cimg::mod(H,(Tfloat)2) - 1)),
          m = V - C;
        Tfloat R, G, B;
        switch ((int)H) {
        case 0 : R = C; G = X; B = 0; break;
        case 1 : R = X; G = C; B = 0; break;
        case 2 : R = 0; G = C; B = X; break;
        case 3 : R = 0; G = X; B = C; break;
        case 4 : R = X; G = 0; B = C; break;
        default : R = C; G = 0; B = X;
        }
        p1[N] = (T)((R + m)*255);
        p2[N] = (T)((G + m)*255);
        p3[N] = (T)((B + m)*255);
      }
      return *this;
    }

    //! Convert pixel values from HSV to RGB color spaces \newinstance.
    CImg<Tuchar> get_HSVtoRGB() const {
      return CImg<Tuchar>(*this,false).HSVtoRGB();
    }

    //! Convert pixel values from RGB to YCbCr color spaces.
    CImg<T>& RGBtoYCbCr() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoYCbCr(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,512))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N],
          G = (Tfloat)p2[N],
          B = (Tfloat)p3[N],
          Y = (66*R + 129*G + 25*B + 128)/256 + 16,
          Cb = (-38*R - 74*G + 112*B + 128)/256 + 128,
          Cr = (112*R - 94*G - 18*B + 128)/256 + 128;
        p1[N] = (T)cimg::cut(Y,(Tfloat)0,(Tfloat)255),
        p2[N] = (T)cimg::cut(Cb,(Tfloat)0,(Tfloat)255),
        p3[N] = (T)cimg::cut(Cr,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from RGB to YCbCr color spaces \newinstance.
    CImg<Tuchar> get_RGBtoYCbCr() const {
      return CImg<Tuchar>(*this,false).RGBtoYCbCr();
    }

    //! Convert pixel values from RGB to YCbCr color spaces.
    CImg<T>& YCbCrtoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "YCbCrtoRGB(): Instance is not a YCbCr image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,512))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          Y = (Tfloat)p1[N] - 16,
          Cb = (Tfloat)p2[N] - 128,
          Cr = (Tfloat)p3[N] - 128,
          R = (298*Y + 409*Cr + 128)/256,
          G = (298*Y - 100*Cb - 208*Cr + 128)/256,
          B = (298*Y + 516*Cb + 128)/256;
        p1[N] = (T)cimg::cut(R,(Tfloat)0,(Tfloat)255),
        p2[N] = (T)cimg::cut(G,(Tfloat)0,(Tfloat)255),
        p3[N] = (T)cimg::cut(B,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from RGB to YCbCr color spaces \newinstance.
    CImg<Tuchar> get_YCbCrtoRGB() const {
      return CImg<Tuchar>(*this,false).YCbCrtoRGB();
    }

    //! Convert pixel values from RGB to YUV color spaces.
    CImg<T>& RGBtoYUV() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoYUV(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,16384))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N]/255,
          G = (Tfloat)p2[N]/255,
          B = (Tfloat)p3[N]/255,
          Y = 0.299f*R + 0.587f*G + 0.114f*B;
        p1[N] = (T)Y;
        p2[N] = (T)(0.492f*(B - Y));
        p3[N] = (T)(0.877*(R - Y));
      }
      return *this;
    }

    //! Convert pixel values from RGB to YUV color spaces \newinstance.
    CImg<Tfloat> get_RGBtoYUV() const {
      return CImg<Tfloat>(*this,false).RGBtoYUV();
    }

    //! Convert pixel values from YUV to RGB color spaces.
    CImg<T>& YUVtoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "YUVtoRGB(): Instance is not a YUV image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,16384))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          Y = (Tfloat)p1[N],
          U = (Tfloat)p2[N],
          V = (Tfloat)p3[N],
          R = (Y + 1.140f*V)*255,
          G = (Y - 0.395f*U - 0.581f*V)*255,
          B = (Y + 2.032f*U)*255;
        p1[N] = (T)cimg::cut(R,(Tfloat)0,(Tfloat)255),
        p2[N] = (T)cimg::cut(G,(Tfloat)0,(Tfloat)255),
        p3[N] = (T)cimg::cut(B,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from YUV to RGB color spaces \newinstance.
    CImg<Tuchar> get_YUVtoRGB() const {
      return CImg<Tuchar>(*this,false).YUVtoRGB();
    }

    //! Convert pixel values from RGB to CMY color spaces.
    CImg<T>& RGBtoCMY() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoCMY(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,2048))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N],
          G = (Tfloat)p2[N],
          B = (Tfloat)p3[N],
          C = 255 - R,
          M = 255 - G,
          Y = 255 - B;
        p1[N] = (T)cimg::cut(C,(Tfloat)0,(Tfloat)255),
        p2[N] = (T)cimg::cut(M,(Tfloat)0,(Tfloat)255),
        p3[N] = (T)cimg::cut(Y,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from RGB to CMY color spaces \newinstance.
    CImg<Tuchar> get_RGBtoCMY() const {
      return CImg<Tfloat>(*this,false).RGBtoCMY();
    }

    //! Convert pixel values from CMY to RGB color spaces.
    CImg<T>& CMYtoRGB() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "CMYtoRGB(): Instance is not a CMY image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,2048))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          C = (Tfloat)p1[N],
          M = (Tfloat)p2[N],
          Y = (Tfloat)p3[N],
          R = 255 - C,
          G = 255 - M,
          B = 255 - Y;
        p1[N] = (T)cimg::cut(R,(Tfloat)0,(Tfloat)255),
        p2[N] = (T)cimg::cut(G,(Tfloat)0,(Tfloat)255),
        p3[N] = (T)cimg::cut(B,(Tfloat)0,(Tfloat)255);
      }
      return *this;
    }

    //! Convert pixel values from CMY to RGB color spaces \newinstance.
    CImg<Tuchar> get_CMYtoRGB() const {
      return CImg<Tuchar>(*this,false).CMYtoRGB();
    }

    //! Convert pixel values from CMY to CMYK color spaces.
    CImg<T>& CMYtoCMYK() {
      return get_CMYtoCMYK().move_to(*this);
    }

    //! Convert pixel values from CMY to CMYK color spaces \newinstance.
    CImg<Tuchar> get_CMYtoCMYK() const {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "CMYtoCMYK(): Instance is not a CMY image.",
                                    cimg_instance);

      CImg<Tfloat> res(_width,_height,_depth,4);
      const T *ps1 = data(0,0,0,0), *ps2 = data(0,0,0,1), *ps3 = data(0,0,0,2);
      Tfloat *pd1 = res.data(0,0,0,0), *pd2 = res.data(0,0,0,1), *pd3 = res.data(0,0,0,2), *pd4 = res.data(0,0,0,3);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,1024))
      for (longT N = 0; N<whd; ++N) {
        Tfloat
          C = (Tfloat)ps1[N],
          M = (Tfloat)ps2[N],
          Y = (Tfloat)ps3[N],
          K = cimg::min(C,M,Y);
        if (K>=255) C = M = Y = 0;
        else { const Tfloat K1 = 255 - K; C = 255*(C - K)/K1; M = 255*(M - K)/K1; Y = 255*(Y - K)/K1; }
        pd1[N] = (Tfloat)cimg::cut(C,(Tfloat)0,(Tfloat)255),
        pd2[N] = (Tfloat)cimg::cut(M,(Tfloat)0,(Tfloat)255),
        pd3[N] = (Tfloat)cimg::cut(Y,(Tfloat)0,(Tfloat)255),
        pd4[N] = (Tfloat)cimg::cut(K,(Tfloat)0,(Tfloat)255);
      }
      return res;
    }

    //! Convert pixel values from CMYK to CMY color spaces.
    CImg<T>& CMYKtoCMY() {
      return get_CMYKtoCMY().move_to(*this);
    }

    //! Convert pixel values from CMYK to CMY color spaces \newinstance.
    CImg<Tfloat> get_CMYKtoCMY() const {
      if (_spectrum!=4)
        throw CImgInstanceException(_cimg_instance
                                    "CMYKtoCMY(): Instance is not a CMYK image.",
                                    cimg_instance);

      CImg<Tfloat> res(_width,_height,_depth,3);
      const T *ps1 = data(0,0,0,0), *ps2 = data(0,0,0,1), *ps3 = data(0,0,0,2), *ps4 = data(0,0,0,3);
      Tfloat *pd1 = res.data(0,0,0,0), *pd2 = res.data(0,0,0,1), *pd3 = res.data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,1024))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          C = (Tfloat)ps1[N],
          M = (Tfloat)ps2[N],
          Y = (Tfloat)ps3[N],
          K = (Tfloat)ps4[N],
          K1 = 1 - K/255,
          nC = C*K1 + K,
          nM = M*K1 + K,
          nY = Y*K1 + K;
        pd1[N] = (Tfloat)cimg::cut(nC,(Tfloat)0,(Tfloat)255),
        pd2[N] = (Tfloat)cimg::cut(nM,(Tfloat)0,(Tfloat)255),
        pd3[N] = (Tfloat)cimg::cut(nY,(Tfloat)0,(Tfloat)255);
      }
      return res;
    }

    //! Convert pixel values from RGB to XYZ color spaces.
    /**
       \param use_D65 Tell to use the D65 illuminant (D50 otherwise).
    **/
    CImg<T>& RGBtoXYZ(const bool use_D65=true) {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "RGBtoXYZ(): Instance is not a RGB image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,2048))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          R = (Tfloat)p1[N]/255,
          G = (Tfloat)p2[N]/255,
          B = (Tfloat)p3[N]/255;
        if (use_D65) { // D65
          p1[N] = (T)(0.4124564*R + 0.3575761*G + 0.1804375*B);
          p2[N] = (T)(0.2126729*R + 0.7151522*G + 0.0721750*B);
          p3[N] = (T)(0.0193339*R + 0.1191920*G + 0.9503041*B);
        } else { // D50
          p1[N] = (T)(0.43603516*R + 0.38511658*G + 0.14305115*B);
          p2[N] = (T)(0.22248840*R + 0.71690369*G + 0.06060791*B);
          p3[N] = (T)(0.01391602*R + 0.09706116*G + 0.71392822*B);
        }
      }
      return *this;
    }

    //! Convert pixel values from RGB to XYZ color spaces \newinstance.
    CImg<Tfloat> get_RGBtoXYZ(const bool use_D65=true) const {
      return CImg<Tfloat>(*this,false).RGBtoXYZ(use_D65);
    }

    //! Convert pixel values from XYZ to RGB color spaces.
    /**
       \param use_D65 Tell to use the D65 illuminant (D50 otherwise).
    **/
    CImg<T>& XYZtoRGB(const bool use_D65=true) {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "XYZtoRGB(): Instance is not a XYZ image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,2048))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          X = (Tfloat)p1[N]*255,
          Y = (Tfloat)p2[N]*255,
          Z = (Tfloat)p3[N]*255;
        if (use_D65) {
          p1[N] = (T)cimg::cut(3.2404542*X - 1.5371385*Y - 0.4985314*Z,0.,255.);
          p2[N] = (T)cimg::cut(-0.9692660*X + 1.8760108*Y + 0.0415560*Z,0.,255.);
          p3[N] = (T)cimg::cut(0.0556434*X - 0.2040259*Y + 1.0572252*Z,0.,255.);
        } else {
          p1[N] = (T)cimg::cut(3.134274799724*X  - 1.617275708956*Y - 0.490724283042*Z,0.,255.);
          p2[N] = (T)cimg::cut(-0.978795575994*X + 1.916161689117*Y + 0.033453331711*Z,0.,255.);
          p3[N] = (T)cimg::cut(0.071976988401*X - 0.228984974402*Y + 1.405718224383*Z,0.,255.);
        }
      }
      return *this;
    }

    //! Convert pixel values from XYZ to RGB color spaces \newinstance.
    CImg<Tuchar> get_XYZtoRGB(const bool use_D65=true) const {
      return CImg<Tuchar>(*this,false).XYZtoRGB(use_D65);
    }

    //! Convert pixel values from XYZ to Lab color spaces.
    CImg<T>& XYZtoLab(const bool use_D65=true) {
#define _cimg_Labf(x) (24389*(x)>216?cimg::cbrt(x):(24389*(x)/27 + 16)/116)

      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "XYZtoLab(): Instance is not a XYZ image.",
                                    cimg_instance);
      const CImg<Tfloat> white = CImg<Tfloat>(1,1,1,3,255).RGBtoXYZ(use_D65);
      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,128))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          X = (Tfloat)(p1[N]/white[0]),
          Y = (Tfloat)(p2[N]/white[1]),
          Z = (Tfloat)(p3[N]/white[2]),
          fX = (Tfloat)_cimg_Labf(X),
          fY = (Tfloat)_cimg_Labf(Y),
          fZ = (Tfloat)_cimg_Labf(Z);
        p1[N] = (T)cimg::cut(116*fY - 16,(Tfloat)0,(Tfloat)100);
        p2[N] = (T)(500*(fX - fY));
        p3[N] = (T)(200*(fY - fZ));
      }
      return *this;
    }

    //! Convert pixel values from XYZ to Lab color spaces \newinstance.
    CImg<Tfloat> get_XYZtoLab(const bool use_D65=true) const {
      return CImg<Tfloat>(*this,false).XYZtoLab(use_D65);
    }

    //! Convert pixel values from Lab to XYZ color spaces.
    CImg<T>& LabtoXYZ(const bool use_D65=true) {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "LabtoXYZ(): Instance is not a Lab image.",
                                    cimg_instance);
      const CImg<Tfloat> white = CImg<Tfloat>(1,1,1,3,255).RGBtoXYZ(use_D65);
      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,128))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          L = (Tfloat)p1[N],
          a = (Tfloat)p2[N],
          b = (Tfloat)p3[N],
          cY = (L + 16)/116,
          cZ = cY - b/200,
          cX = a/500 + cY,
          X = (Tfloat)(24389*cX>216?cX*cX*cX:(116*cX - 16)*27/24389),
          Y = (Tfloat)(27*L>216?cY*cY*cY:27*L/24389),
          Z = (Tfloat)(24389*cZ>216?cZ*cZ*cZ:(116*cZ - 16)*27/24389);
        p1[N] = (T)(X*white[0]);
        p2[N] = (T)(Y*white[1]);
        p3[N] = (T)(Z*white[2]);
      }
      return *this;
    }

    //! Convert pixel values from Lab to XYZ color spaces \newinstance.
    CImg<Tfloat> get_LabtoXYZ(const bool use_D65=true) const {
      return CImg<Tfloat>(*this,false).LabtoXYZ(use_D65);
    }

    //! Convert pixel values from XYZ to xyY color spaces.
    CImg<T>& XYZtoxyY() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "XYZtoxyY(): Instance is not a XYZ image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,4096))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
          X = (Tfloat)p1[N],
          Y = (Tfloat)p2[N],
          Z = (Tfloat)p3[N],
          sum = X + Y + Z,
          nsum = sum>0?sum:1;
        p1[N] = (T)(X/nsum);
        p2[N] = (T)(Y/nsum);
        p3[N] = (T)Y;
      }
      return *this;
    }

    //! Convert pixel values from XYZ to xyY color spaces \newinstance.
    CImg<Tfloat> get_XYZtoxyY() const {
      return CImg<Tfloat>(*this,false).XYZtoxyY();
    }

    //! Convert pixel values from xyY to XYZ color spaces.
    CImg<T>& xyYtoXYZ() {
      if (_spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "xyYtoXYZ(): Instance is not a xyY image.",
                                    cimg_instance);

      T *p1 = data(0,0,0,0), *p2 = data(0,0,0,1), *p3 = data(0,0,0,2);
      const longT whd = (longT)width()*height()*depth();
      cimg_pragma_openmp(parallel for cimg_openmp_if_size(whd,4096))
      for (longT N = 0; N<whd; ++N) {
        const Tfloat
         px = (Tfloat)p1[N],
         py = (Tfloat)p2[N],
         Y = (Tfloat)p3[N],
         ny = py>0?py:1;
        p1[N] = (T)(px*Y/ny);
        p2[N] = (T)Y;
        p3[N] = (T)((1 - px - py)*Y/ny);
      }
      return *this;
    }

    //! Convert pixel values from xyY to XYZ color spaces \newinstance.
    CImg<Tfloat> get_xyYtoXYZ() const {
      return CImg<Tfloat>(*this,false).xyYtoXYZ();
    }

    //! Convert pixel values from RGB to Lab color spaces.
    CImg<T>& RGBtoLab(const bool use_D65=true) {
      return RGBtoXYZ(use_D65).XYZtoLab(use_D65);
    }

    //! Convert pixel values from RGB to Lab color spaces \newinstance.
    CImg<Tfloat> get_RGBtoLab(const bool use_D65=true) const {
      return CImg<Tfloat>(*this,false).RGBtoLab(use_D65);
    }

    //! Convert pixel values from Lab to RGB color spaces.
    CImg<T>& LabtoRGB(const bool use_D65=true) {
      return LabtoXYZ().XYZtoRGB(use_D65);
    }

    //! Convert pixel values from Lab to RGB color spaces \newinstance.
    CImg<Tuchar> get_LabtoRGB(const bool use_D65=true) const {
      return CImg<Tuchar>(*this,false).LabtoRGB(use_D65);
    }

    //! Convert pixel values from RGB to xyY color spaces.
    CImg<T>& RGBtoxyY(const bool use_D65=true) {
      return RGBtoXYZ(use_D65).XYZtoxyY();
    }

    //! Convert pixel values from RGB to xyY color spaces \newinstance.
    CImg<Tfloat> get_RGBtoxyY(const bool use_D65=true) const {
      return CImg<Tfloat>(*this,false).RGBtoxyY(use_D65);
    }

    //! Convert pixel values from xyY to RGB color spaces.
    CImg<T>& xyYtoRGB(const bool use_D65=true) {
      return xyYtoXYZ().XYZtoRGB(use_D65);
    }

    //! Convert pixel values from xyY to RGB color spaces \newinstance.
    CImg<Tuchar> get_xyYtoRGB(const bool use_D65=true) const {
      return CImg<Tuchar>(*this,false).xyYtoRGB(use_D65);
    }

    //! Convert pixel values from RGB to CMYK color spaces.
    CImg<T>& RGBtoCMYK() {
      return RGBtoCMY().CMYtoCMYK();
    }

    //! Convert pixel values from RGB to CMYK color spaces \newinstance.
    CImg<Tfloat> get_RGBtoCMYK() const {
      return CImg<Tfloat>(*this,false).RGBtoCMYK();
    }

    //! Convert pixel values from CMYK to RGB color spaces.
    CImg<T>& CMYKtoRGB() {
      return CMYKtoCMY().CMYtoRGB();
    }

    //! Convert pixel values from CMYK to RGB color spaces \newinstance.
    CImg<Tuchar> get_CMYKtoRGB() const {
      return CImg<Tuchar>(*this,false).CMYKtoRGB();
    }

    //@}
    //------------------------------------------
    //
    //! \name Geometric / Spatial Manipulation
    //@{
    //------------------------------------------

    static float _cimg_lanczos(const float x) {
      if (x<=-2 || x>=2) return 0;
      const float a = (float)cimg::PI*x, b = 0.5f*a;
      return (float)(x?std::sin(a)*std::sin(b)/(a*b):1);
    }

    //! Resize image to new dimensions.
    /**
       \param size_x Number of columns (new size along the X-axis).
       \param size_y Number of rows (new size along the Y-axis).
       \param size_z Number of slices (new size along the Z-axis).
       \param size_c Number of vector-channels (new size along the C-axis).
       \param interpolation_type Method of interpolation:
       - -1 = no interpolation: raw memory resizing.
       - 0 = no interpolation: additional space is filled according to \p boundary_conditions.
       - 1 = nearest-neighbor interpolation.
       - 2 = moving average interpolation.
       - 3 = linear interpolation.
       - 4 = grid interpolation.
       - 5 = cubic interpolation.
       - 6 = lanczos interpolation.
       \param boundary_conditions Type of boundary conditions used if necessary.
       \param centering_x Set centering type (only if \p interpolation_type=0).
       \param centering_y Set centering type (only if \p interpolation_type=0).
       \param centering_z Set centering type (only if \p interpolation_type=0).
       \param centering_c Set centering type (only if \p interpolation_type=0).
       \note If pd[x,y,z,v]<0, it corresponds to a percentage of the original size (the default value is -100).
    **/
    CImg<T>& resize(const int size_x, const int size_y=-100,
                    const int size_z=-100, const int size_c=-100,
                    const int interpolation_type=1, const unsigned int boundary_conditions=0,
                    const float centering_x = 0, const float centering_y = 0,
                    const float centering_z = 0, const float centering_c = 0) {
      if (!size_x || !size_y || !size_z || !size_c) return assign();
      const unsigned int
        _sx = (unsigned int)(size_x<0?-size_x*width()/100:size_x),
        _sy = (unsigned int)(size_y<0?-size_y*height()/100:size_y),
        _sz = (unsigned int)(size_z<0?-size_z*depth()/100:size_z),
        _sc = (unsigned int)(size_c<0?-size_c*spectrum()/100:size_c),
        sx = _sx?_sx:1, sy = _sy?_sy:1, sz = _sz?_sz:1, sc = _sc?_sc:1;
      if (sx==_width && sy==_height && sz==_depth && sc==_spectrum) return *this;
      if (is_empty()) return assign(sx,sy,sz,sc,(T)0);
      if (interpolation_type==-1 && sx*sy*sz*sc==size()) {
        _width = sx; _height = sy; _depth = sz; _spectrum = sc;
        return *this;
      }
      return get_resize(sx,sy,sz,sc,interpolation_type,boundary_conditions,
                        centering_x,centering_y,centering_z,centering_c).move_to(*this);
    }

    //! Resize image to new dimensions \newinstance.
    CImg<T> get_resize(const int size_x, const int size_y = -100,
                       const int size_z = -100, const int size_c = -100,
                       const int interpolation_type=1, const unsigned int boundary_conditions=0,
                       const float centering_x = 0, const float centering_y = 0,
                       const float centering_z = 0, const float centering_c = 0) const {
      if (centering_x<0 || centering_x>1 || centering_y<0 || centering_y>1 ||
          centering_z<0 || centering_z>1 || centering_c<0 || centering_c>1)
        throw CImgArgumentException(_cimg_instance
                                    "resize(): Specified centering arguments (%g,%g,%g,%g) are outside range [0,1].",
                                    cimg_instance,
                                    centering_x,centering_y,centering_z,centering_c);

      if (!size_x || !size_y || !size_z || !size_c) return CImg<T>();
      const unsigned int
        sx = std::max(1U,(unsigned int)(size_x>=0?size_x:-size_x*width()/100)),
        sy = std::max(1U,(unsigned int)(size_y>=0?size_y:-size_y*height()/100)),
        sz = std::max(1U,(unsigned int)(size_z>=0?size_z:-size_z*depth()/100)),
        sc = std::max(1U,(unsigned int)(size_c>=0?size_c:-size_c*spectrum()/100));
      if (sx==_width && sy==_height && sz==_depth && sc==_spectrum) return +*this;
      if (is_empty()) return CImg<T>(sx,sy,sz,sc,(T)0);
      CImg<T> res;
      switch (interpolation_type) {

        // Raw resizing.
        //
      case -1 :
        std::memcpy(res.assign(sx,sy,sz,sc,(T)0)._data,_data,sizeof(T)*std::min(size(),(ulongT)sx*sy*sz*sc));
        break;

        // No interpolation.
        //
      case 0 : {
        const int
          xc = (int)(centering_x*((int)sx - width())),
          yc = (int)(centering_y*((int)sy - height())),
          zc = (int)(centering_z*((int)sz - depth())),
          cc = (int)(centering_c*((int)sc - spectrum()));
        get_crop(-xc,-yc,-zc,-cc,sx - xc - 1,sy - yc - 1,sz - zc - 1,sc - cc - 1,boundary_conditions).move_to(res);
      } break;

        // Nearest neighbor interpolation.
        //
      case 1 : {
        res.assign(sx,sy,sz,sc);
        CImg<ulongT> off_x(sx), off_y(sy + 1), off_z(sz + 1), off_c(sc + 1);
        const ulongT
          wh = (ulongT)_width*_height,
          whd = (ulongT)_width*_height*_depth,
          sxy = (ulongT)sx*sy,
          sxyz = (ulongT)sx*sy*sz,
          one = (ulongT)1;
        if (sx==_width) off_x.fill(1);
        else {
          ulongT *poff_x = off_x._data, curr = 0;
          cimg_forX(res,x) {
            const ulongT old = curr;
            curr = (x + one)*_width/sx;
            *(poff_x++) = curr - old;
          }
        }
        if (sy==_height) off_y.fill(_width);
        else {
          ulongT *poff_y = off_y._data, curr = 0;
          cimg_forY(res,y) {
            const ulongT old = curr;
            curr = (y + one)*_height/sy;
            *(poff_y++) = _width*(curr - old);
          }
          *poff_y = 0;
        }
        if (sz==_depth) off_z.fill(wh);
        else {
          ulongT *poff_z = off_z._data, curr = 0;
          cimg_forZ(res,z) {
            const ulongT old = curr;
            curr = (z + one)*_depth/sz;
            *(poff_z++) = wh*(curr - old);
          }
          *poff_z = 0;
        }
        if (sc==_spectrum) off_c.fill(whd);
        else {
          ulongT *poff_c = off_c._data, curr = 0;
          cimg_forC(res,c) {
            const ulongT old = curr;
            curr = (c + one)*_spectrum/sc;
            *(poff_c++) = whd*(curr - old);
          }
          *poff_c = 0;
        }

        T *ptrd = res._data;
        const T* ptrc = _data;
        const ulongT *poff_c = off_c._data;
        for (unsigned int c = 0; c<sc; ) {
          const T *ptrz = ptrc;
          const ulongT *poff_z = off_z._data;
          for (unsigned int z = 0; z<sz; ) {
            const T *ptry = ptrz;
            const ulongT *poff_y = off_y._data;
            for (unsigned int y = 0; y<sy; ) {
              const T *ptrx = ptry;
              const ulongT *poff_x = off_x._data;
              cimg_forX(res,x) { *(ptrd++) = *ptrx; ptrx+=*(poff_x++); }
              ++y;
              ulongT dy = *(poff_y++);
              for ( ; !dy && y<dy; std::memcpy(ptrd,ptrd - sx,sizeof(T)*sx), ++y, ptrd+=sx, dy = *(poff_y++)) {}
              ptry+=dy;
            }
            ++z;
            ulongT dz = *(poff_z++);
            for ( ; !dz && z<dz; std::memcpy(ptrd,ptrd - sxy,sizeof(T)*sxy), ++z, ptrd+=sxy, dz = *(poff_z++)) {}
            ptrz+=dz;
          }
          ++c;
          ulongT dc = *(poff_c++);
          for ( ; !dc && c<dc; std::memcpy(ptrd,ptrd - sxyz,sizeof(T)*sxyz), ++c, ptrd+=sxyz, dc = *(poff_c++)) {}
          ptrc+=dc;
        }
      } break;

        // Moving average.
        //
      case 2 : {
        bool instance_first = true;
        if (sx==1 && sy==1 && sz==1 && sc==_spectrum) { // Particular case: Spatial averaging
          res.assign(1,1,1,_spectrum);
          cimg_forC(res,c) res[c] = (T)get_shared_channel(c).mean();
        } else {
          if (sx!=_width) {
            if (sx>_width) get_resize(sx,_height,_depth,_spectrum,1).move_to(res);
            else {
              CImg<Tfloat> tmp(sx,_height,_depth,_spectrum,0);
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(sx>=256 && _height*_depth*_spectrum>=256))
                cimg_forYZC(tmp,y,z,v) {
                for (unsigned int a = _width*sx, b = _width, c = sx, s = 0, t = 0; a; ) {
                  const unsigned int d = std::min(b,c);
                  a-=d; b-=d; c-=d;
                  tmp(t,y,z,v)+=(Tfloat)(*this)(s,y,z,v)*d;
                  if (!b) { tmp(t++,y,z,v)/=_width; b = _width; }
                  if (!c) { ++s; c = sx; }
                }
              }
              tmp.move_to(res);
            }
            instance_first = false;
          }

          if (sy!=_height) {
            if (sy>_height) get_resize(sx,sy,_depth,_spectrum,1).move_to(res);
            else {
              CImg<Tfloat> tmp(sx,sy,_depth,_spectrum,0);
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(sy>=256 && _width*_depth*_spectrum>=256))
                cimg_forXZC(tmp,x,z,v) {
                for (unsigned int a = _height*sy, b = _height, c = sy, s = 0, t = 0; a; ) {
                  const unsigned int d = std::min(b,c);
                  a-=d; b-=d; c-=d;
                  if (instance_first) tmp(x,t,z,v)+=(Tfloat)(*this)(x,s,z,v)*d;
                  else tmp(x,t,z,v)+=(Tfloat)res(x,s,z,v)*d;
                  if (!b) { tmp(x,t++,z,v)/=_height; b = _height; }
                  if (!c) { ++s; c = sy; }
                }
              }
              tmp.move_to(res);
            }
            instance_first = false;
          }

          if (sz!=_depth) {
            if (sz>_depth) get_resize(sx,sy,sz,_spectrum,1).move_to(res);
            else {
              CImg<Tfloat> tmp(sx,sy,sz,_spectrum,0);
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(sz>=256 && _width*_height*_spectrum>=256))
                cimg_forXYC(tmp,x,y,v) {
                for (unsigned int a = _depth*sz, b = _depth, c = sz, s = 0, t = 0; a; ) {
                  const unsigned int d = std::min(b,c);
                  a-=d; b-=d; c-=d;
                  if (instance_first) tmp(x,y,t,v)+=(Tfloat)(*this)(x,y,s,v)*d;
                  else tmp(x,y,t,v)+=(Tfloat)res(x,y,s,v)*d;
                  if (!b) { tmp(x,y,t++,v)/=_depth; b = _depth; }
                  if (!c) { ++s; c = sz; }
                }
              }
              tmp.move_to(res);
            }
            instance_first = false;
          }

          if (sc!=_spectrum) {
            if (sc>_spectrum) get_resize(sx,sy,sz,sc,1).move_to(res);
            else {
              CImg<Tfloat> tmp(sx,sy,sz,sc,0);
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(sc>=256 && _width*_height*_depth>=256))
                cimg_forXYZ(tmp,x,y,z) {
                for (unsigned int a = _spectrum*sc, b = _spectrum, c = sc, s = 0, t = 0; a; ) {
                  const unsigned int d = std::min(b,c);
                  a-=d; b-=d; c-=d;
                  if (instance_first) tmp(x,y,z,t)+=(Tfloat)(*this)(x,y,z,s)*d;
                  else tmp(x,y,z,t)+=(Tfloat)res(x,y,z,s)*d;
                  if (!b) { tmp(x,y,z,t++)/=_spectrum; b = _spectrum; }
                  if (!c) { ++s; c = sc; }
                }
              }
              tmp.move_to(res);
            }
            instance_first = false;
          }
        }

      } break;

        // Linear interpolation.
        //
      case 3 : {
        CImg<uintT> off(cimg::max(sx,sy,sz,sc));
        CImg<doubleT> foff(off._width);
        CImg<T> resx, resy, resz, resc;
        double curr, old;

        if (sx!=_width) {
          if (_width==1) get_resize(sx,_height,_depth,_spectrum,1).move_to(resx);
          else if (_width>sx) get_resize(sx,_height,_depth,_spectrum,2).move_to(resx);
          else {
            const double fx = (!boundary_conditions && sx>_width)?(sx>1?(_width - 1.)/(sx - 1):0):
              (double)_width/sx;
            resx.assign(sx,_height,_depth,_spectrum);
            curr = old = 0;
            {
              unsigned int *poff = off._data;
              double *pfoff = foff._data;
              cimg_forX(resx,x) {
                *(pfoff++) = curr - (unsigned int)curr;
                old = curr;
                curr = std::min(width() - 1.,curr + fx);
                *(poff++) = (unsigned int)curr - (unsigned int)old;
              }
            }
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                               cimg_openmp_if(resx._width>=256 && resx._height*resx._depth*resx._spectrum>=256))
            cimg_forYZC(resx,y,z,c) {
              const T *ptrs = data(0,y,z,c), *const ptrsmax = ptrs + _width - 1;
              T *ptrd = resx.data(0,y,z,c);
              const unsigned int *poff = off._data;
              const double *pfoff = foff._data;
              cimg_forX(resx,x) {
                const double alpha = *(pfoff++);
                const T val1 = *ptrs, val2 = ptrs<ptrsmax?*(ptrs + 1):val1;
                *(ptrd++) = (T)((1 - alpha)*val1 + alpha*val2);
                ptrs+=*(poff++);
              }
            }
          }
        } else resx.assign(*this,true);

        if (sy!=_height) {
          if (_height==1) resx.get_resize(sx,sy,_depth,_spectrum,1).move_to(resy);
          else {
            if (_height>sy) resx.get_resize(sx,sy,_depth,_spectrum,2).move_to(resy);
            else {
              const double fy = (!boundary_conditions && sy>_height)?(sy>1?(_height - 1.)/(sy - 1):0):
                (double)_height/sy;
              resy.assign(sx,sy,_depth,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(height() - 1.,curr + fy);
                  *(poff++) = sx*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resy._height>=256 && resy._width*resy._depth*resy._spectrum>=256))
              cimg_forXZC(resy,x,z,c) {
                const T *ptrs = resx.data(x,0,z,c), *const ptrsmax = ptrs + (_height - 1)*sx;
                T *ptrd = resy.data(x,0,z,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  const double alpha = *(pfoff++);
                  const T val1 = *ptrs, val2 = ptrs<ptrsmax?*(ptrs + sx):val1;
                  *ptrd = (T)((1 - alpha)*val1 + alpha*val2);
                  ptrd+=sx;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resx.assign();
        } else resy.assign(resx,true);

        if (sz!=_depth) {
          if (_depth==1) resy.get_resize(sx,sy,sz,_spectrum,1).move_to(resz);
          else {
            if (_depth>sz) resy.get_resize(sx,sy,sz,_spectrum,2).move_to(resz);
            else {
              const double fz = (!boundary_conditions && sz>_depth)?(sz>1?(_depth - 1.)/(sz - 1):0):
                (double)_depth/sz;
              const unsigned int sxy = sx*sy;
              resz.assign(sx,sy,sz,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(depth() - 1.,curr + fz);
                  *(poff++) = sxy*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resz._depth>=256 && resz._width*resz._height*resz._spectrum>=256))
              cimg_forXYC(resz,x,y,c) {
                const T *ptrs = resy.data(x,y,0,c), *const ptrsmax = ptrs + (_depth - 1)*sxy;
                T *ptrd = resz.data(x,y,0,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  const double alpha = *(pfoff++);
                  const T val1 = *ptrs, val2 = ptrs<ptrsmax?*(ptrs + sxy):val1;
                  *ptrd = (T)((1 - alpha)*val1 + alpha*val2);
                  ptrd+=sxy;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resy.assign();
        } else resz.assign(resy,true);

        if (sc!=_spectrum) {
          if (_spectrum==1) resz.get_resize(sx,sy,sz,sc,1).move_to(resc);
          else {
            if (_spectrum>sc) resz.get_resize(sx,sy,sz,sc,2).move_to(resc);
            else {
              const double fc = (!boundary_conditions && sc>_spectrum)?(sc>1?(_spectrum - 1.)/(sc - 1):0):
                (double)_spectrum/sc;
              const unsigned int sxyz = sx*sy*sz;
              resc.assign(sx,sy,sz,sc);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(spectrum() - 1.,curr + fc);
                  *(poff++) = sxyz*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resc._spectrum>=256 && resc._width*resc._height*resc._depth>=256))
              cimg_forXYZ(resc,x,y,z) {
                const T *ptrs = resz.data(x,y,z,0), *const ptrsmax = ptrs + (_spectrum - 1)*sxyz;
                T *ptrd = resc.data(x,y,z,0);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  const double alpha = *(pfoff++);
                  const T val1 = *ptrs, val2 = ptrs<ptrsmax?*(ptrs + sxyz):val1;
                  *ptrd = (T)((1 - alpha)*val1 + alpha*val2);
                  ptrd+=sxyz;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resz.assign();
        } else resc.assign(resz,true);
        return resc._is_shared?(resz._is_shared?(resy._is_shared?(resx._is_shared?(+(*this)):resx):resy):resz):resc;
      } break;

        // Grid interpolation.
        //
      case 4 : {
        CImg<T> resx, resy, resz, resc;
        if (sx!=_width) {
          if (sx<_width) get_resize(sx,_height,_depth,_spectrum,1).move_to(resx);
          else {
            resx.assign(sx,_height,_depth,_spectrum,(T)0);
            const int dx = (int)(2*sx), dy = 2*width();
            int err = (int)(dy + centering_x*(sx*dy/width() - dy)), xs = 0;
            cimg_forX(resx,x) if ((err-=dy)<=0) {
              cimg_forYZC(resx,y,z,c) resx(x,y,z,c) = (*this)(xs,y,z,c);
              ++xs;
              err+=dx;
            }
          }
        } else resx.assign(*this,true);

        if (sy!=_height) {
          if (sy<_height) resx.get_resize(sx,sy,_depth,_spectrum,1).move_to(resy);
          else {
            resy.assign(sx,sy,_depth,_spectrum,(T)0);
            const int dx = (int)(2*sy), dy = 2*height();
            int err = (int)(dy + centering_y*(sy*dy/height() - dy)), ys = 0;
            cimg_forY(resy,y) if ((err-=dy)<=0) {
              cimg_forXZC(resy,x,z,c) resy(x,y,z,c) = resx(x,ys,z,c);
              ++ys;
              err+=dx;
            }
          }
          resx.assign();
        } else resy.assign(resx,true);

        if (sz!=_depth) {
          if (sz<_depth) resy.get_resize(sx,sy,sz,_spectrum,1).move_to(resz);
          else {
            resz.assign(sx,sy,sz,_spectrum,(T)0);
            const int dx = (int)(2*sz), dy = 2*depth();
            int err = (int)(dy + centering_z*(sz*dy/depth() - dy)), zs = 0;
            cimg_forZ(resz,z) if ((err-=dy)<=0) {
              cimg_forXYC(resz,x,y,c) resz(x,y,z,c) = resy(x,y,zs,c);
              ++zs;
              err+=dx;
            }
          }
          resy.assign();
        } else resz.assign(resy,true);

        if (sc!=_spectrum) {
          if (sc<_spectrum) resz.get_resize(sx,sy,sz,sc,1).move_to(resc);
          else {
            resc.assign(sx,sy,sz,sc,(T)0);
            const int dx = (int)(2*sc), dy = 2*spectrum();
            int err = (int)(dy + centering_c*(sc*dy/spectrum() - dy)), cs = 0;
            cimg_forC(resc,c) if ((err-=dy)<=0) {
              cimg_forXYZ(resc,x,y,z) resc(x,y,z,c) = resz(x,y,z,cs);
              ++cs;
              err+=dx;
            }
          }
          resz.assign();
        } else resc.assign(resz,true);

        return resc._is_shared?(resz._is_shared?(resy._is_shared?(resx._is_shared?(+(*this)):resx):resy):resz):resc;
      } break;

        // Cubic interpolation.
        //
      case 5 : {
        const Tfloat vmin = (Tfloat)cimg::type<T>::min(), vmax = (Tfloat)cimg::type<T>::max();
        CImg<uintT> off(cimg::max(sx,sy,sz,sc));
        CImg<doubleT> foff(off._width);
        CImg<T> resx, resy, resz, resc;
        double curr, old;

        if (sx!=_width) {
          if (_width==1) get_resize(sx,_height,_depth,_spectrum,1).move_to(resx);
          else {
            if (_width>sx) get_resize(sx,_height,_depth,_spectrum,2).move_to(resx);
            else {
              const double fx = (!boundary_conditions && sx>_width)?(sx>1?(_width - 1.)/(sx - 1):0):
                (double)_width/sx;
              resx.assign(sx,_height,_depth,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forX(resx,x) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(width() - 1.,curr + fx);
                  *(poff++) = (unsigned int)curr - (unsigned int)old;
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resx._width>=256 && resx._height*resx._depth*resx._spectrum>=256))
              cimg_forYZC(resx,y,z,c) {
                const T *const ptrs0 = data(0,y,z,c), *ptrs = ptrs0, *const ptrsmax = ptrs + (_width - 2);
                T *ptrd = resx.data(0,y,z,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forX(resx,x) {
                  const double
                    t = *(pfoff++),
                    val1 = (double)*ptrs,
                    val0 = ptrs>ptrs0?(double)*(ptrs - 1):val1,
                    val2 = ptrs<=ptrsmax?(double)*(ptrs + 1):val1,
                    val3 = ptrs<ptrsmax?(double)*(ptrs + 2):val2,
                    val = val1 + 0.5f*(t*(-val0 + val2) + t*t*(2*val0 - 5*val1 + 4*val2 - val3) +
                                       t*t*t*(-val0 + 3*val1 - 3*val2 + val3));
                  *(ptrd++) = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrs+=*(poff++);
                }
              }
            }
          }
        } else resx.assign(*this,true);

        if (sy!=_height) {
          if (_height==1) resx.get_resize(sx,sy,_depth,_spectrum,1).move_to(resy);
          else {
            if (_height>sy) resx.get_resize(sx,sy,_depth,_spectrum,2).move_to(resy);
            else {
              const double fy = (!boundary_conditions && sy>_height)?(sy>1?(_height - 1.)/(sy - 1):0):
                (double)_height/sy;
              resy.assign(sx,sy,_depth,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(height() - 1.,curr + fy);
                  *(poff++) = sx*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resy._height>=256 && resy._width*resy._depth*resy._spectrum>=256))
              cimg_forXZC(resy,x,z,c) {
                const T *const ptrs0 = resx.data(x,0,z,c), *ptrs = ptrs0, *const ptrsmax = ptrs + (_height - 2)*sx;
                T *ptrd = resy.data(x,0,z,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  const double
                    t = *(pfoff++),
                    val1 = (double)*ptrs,
                    val0 = ptrs>ptrs0?(double)*(ptrs - sx):val1,
                    val2 = ptrs<=ptrsmax?(double)*(ptrs + sx):val1,
                    val3 = ptrs<ptrsmax?(double)*(ptrs + 2*sx):val2,
                    val = val1 + 0.5f*(t*(-val0 + val2) + t*t*(2*val0 - 5*val1 + 4*val2 - val3) +
                                       t*t*t*(-val0 + 3*val1 - 3*val2 + val3));
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sx;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resx.assign();
        } else resy.assign(resx,true);

        if (sz!=_depth) {
          if (_depth==1) resy.get_resize(sx,sy,sz,_spectrum,1).move_to(resz);
          else {
            if (_depth>sz) resy.get_resize(sx,sy,sz,_spectrum,2).move_to(resz);
            else {
              const double fz = (!boundary_conditions && sz>_depth)?(sz>1?(_depth - 1.)/(sz - 1):0):
                (double)_depth/sz;
              const unsigned int sxy = sx*sy;
              resz.assign(sx,sy,sz,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(depth() - 1.,curr + fz);
                  *(poff++) = sxy*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resz._depth>=256 && resz._width*resz._height*resz._spectrum>=256))
              cimg_forXYC(resz,x,y,c) {
                const T *const ptrs0 = resy.data(x,y,0,c), *ptrs = ptrs0, *const ptrsmax = ptrs + (_depth - 2)*sxy;
                T *ptrd = resz.data(x,y,0,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  const double
                    t = *(pfoff++),
                    val1 = (double)*ptrs,
                    val0 = ptrs>ptrs0?(double)*(ptrs - sxy):val1,
                    val2 = ptrs<=ptrsmax?(double)*(ptrs + sxy):val1,
                    val3 = ptrs<ptrsmax?(double)*(ptrs + 2*sxy):val2,
                    val = val1 + 0.5f*(t*(-val0 + val2) + t*t*(2*val0 - 5*val1 + 4*val2 - val3) +
                                       t*t*t*(-val0 + 3*val1 - 3*val2 + val3));
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sxy;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resy.assign();
        } else resz.assign(resy,true);

        if (sc!=_spectrum) {
          if (_spectrum==1) resz.get_resize(sx,sy,sz,sc,1).move_to(resc);
          else {
            if (_spectrum>sc) resz.get_resize(sx,sy,sz,sc,2).move_to(resc);
            else {
              const double fc = (!boundary_conditions && sc>_spectrum)?(sc>1?(_spectrum - 1.)/(sc - 1):0):
                (double)_spectrum/sc;
              const unsigned int sxyz = sx*sy*sz;
              resc.assign(sx,sy,sz,sc);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(spectrum() - 1.,curr + fc);
                  *(poff++) = sxyz*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resc._spectrum>=256 && resc._width*resc._height*resc._depth>=256))
              cimg_forXYZ(resc,x,y,z) {
                const T *const ptrs0 = resz.data(x,y,z,0), *ptrs = ptrs0, *const ptrsmax = ptrs + (_spectrum - 2)*sxyz;
                T *ptrd = resc.data(x,y,z,0);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  const double
                    t = *(pfoff++),
                    val1 = (double)*ptrs,
                    val0 = ptrs>ptrs0?(double)*(ptrs - sxyz):val1,
                    val2 = ptrs<=ptrsmax?(double)*(ptrs + sxyz):val1,
                    val3 = ptrs<ptrsmax?(double)*(ptrs + 2*sxyz):val2,
                    val = val1 + 0.5f*(t*(-val0 + val2) + t*t*(2*val0 - 5*val1 + 4*val2 - val3) +
                                       t*t*t*(-val0 + 3*val1 - 3*val2 + val3));
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sxyz;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resz.assign();
        } else resc.assign(resz,true);

        return resc._is_shared?(resz._is_shared?(resy._is_shared?(resx._is_shared?(+(*this)):resx):resy):resz):resc;
      } break;

        // Lanczos interpolation.
        //
      case 6 : {
        const double vmin = (double)cimg::type<T>::min(), vmax = (double)cimg::type<T>::max();
        CImg<uintT> off(cimg::max(sx,sy,sz,sc));
        CImg<doubleT> foff(off._width);
        CImg<T> resx, resy, resz, resc;
        double curr, old;

        if (sx!=_width) {
          if (_width==1) get_resize(sx,_height,_depth,_spectrum,1).move_to(resx);
          else {
            if (_width>sx) get_resize(sx,_height,_depth,_spectrum,2).move_to(resx);
            else {
              const double fx = (!boundary_conditions && sx>_width)?(sx>1?(_width - 1.)/(sx - 1):0):
                (double)_width/sx;
              resx.assign(sx,_height,_depth,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forX(resx,x) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(width() - 1.,curr + fx);
                  *(poff++) = (unsigned int)curr - (unsigned int)old;
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resx._width>=256 && resx._height*resx._depth*resx._spectrum>=256))
              cimg_forYZC(resx,y,z,c) {
                const T *const ptrs0 = data(0,y,z,c), *ptrs = ptrs0, *const ptrsmin = ptrs0 + 1,
                  *const ptrsmax = ptrs0 + (_width - 2);
                T *ptrd = resx.data(0,y,z,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forX(resx,x) {
                  const double
                    t = *(pfoff++),
                    w0 = _cimg_lanczos(t + 2),
                    w1 = _cimg_lanczos(t + 1),
                    w2 = _cimg_lanczos(t),
                    w3 = _cimg_lanczos(t - 1),
                    w4 = _cimg_lanczos(t - 2),
                    val2 = (double)*ptrs,
                    val1 = ptrs>=ptrsmin?(double)*(ptrs - 1):val2,
                    val0 = ptrs>ptrsmin?(double)*(ptrs - 2):val1,
                    val3 = ptrs<=ptrsmax?(double)*(ptrs + 1):val2,
                    val4 = ptrs<ptrsmax?(double)*(ptrs + 2):val3,
                    val = (val0*w0 + val1*w1 + val2*w2 + val3*w3 + val4*w4)/(w1 + w2 + w3 + w4);
                  *(ptrd++) = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrs+=*(poff++);
                }
              }
            }
          }
        } else resx.assign(*this,true);

        if (sy!=_height) {
          if (_height==1) resx.get_resize(sx,sy,_depth,_spectrum,1).move_to(resy);
          else {
            if (_height>sy) resx.get_resize(sx,sy,_depth,_spectrum,2).move_to(resy);
            else {
              const double fy = (!boundary_conditions && sy>_height)?(sy>1?(_height - 1.)/(sy - 1):0):
                (double)_height/sy;
              resy.assign(sx,sy,_depth,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(height() - 1.,curr + fy);
                  *(poff++) = sx*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resy._height>=256 && resy._width*resy._depth*resy._spectrum>=256))
              cimg_forXZC(resy,x,z,c) {
                const T *const ptrs0 = resx.data(x,0,z,c), *ptrs = ptrs0, *const ptrsmin = ptrs0 + sx,
                  *const ptrsmax = ptrs0 + (_height - 2)*sx;
                T *ptrd = resy.data(x,0,z,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forY(resy,y) {
                  const double
                    t = *(pfoff++),
                    w0 = _cimg_lanczos(t + 2),
                    w1 = _cimg_lanczos(t + 1),
                    w2 = _cimg_lanczos(t),
                    w3 = _cimg_lanczos(t - 1),
                    w4 = _cimg_lanczos(t - 2),
                    val2 = (double)*ptrs,
                    val1 = ptrs>=ptrsmin?(double)*(ptrs - sx):val2,
                    val0 = ptrs>ptrsmin?(double)*(ptrs - 2*sx):val1,
                    val3 = ptrs<=ptrsmax?(double)*(ptrs + sx):val2,
                    val4 = ptrs<ptrsmax?(double)*(ptrs + 2*sx):val3,
                    val = (val0*w0 + val1*w1 + val2*w2 + val3*w3 + val4*w4)/(w1 + w2 + w3 + w4);
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sx;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resx.assign();
        } else resy.assign(resx,true);

        if (sz!=_depth) {
          if (_depth==1) resy.get_resize(sx,sy,sz,_spectrum,1).move_to(resz);
          else {
            if (_depth>sz) resy.get_resize(sx,sy,sz,_spectrum,2).move_to(resz);
            else {
              const double fz = (!boundary_conditions && sz>_depth)?(sz>1?(_depth - 1.)/(sz - 1):0):
                (double)_depth/sz;
              const unsigned int sxy = sx*sy;
              resz.assign(sx,sy,sz,_spectrum);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(depth() - 1.,curr + fz);
                  *(poff++) = sxy*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resz._depth>=256 && resz._width*resz._height*resz._spectrum>=256))
              cimg_forXYC(resz,x,y,c) {
                const T *const ptrs0 = resy.data(x,y,0,c), *ptrs = ptrs0, *const ptrsmin = ptrs0 + sxy,
                  *const ptrsmax = ptrs0 + (_depth - 2)*sxy;
                T *ptrd = resz.data(x,y,0,c);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forZ(resz,z) {
                  const double
                    t = *(pfoff++),
                    w0 = _cimg_lanczos(t + 2),
                    w1 = _cimg_lanczos(t + 1),
                    w2 = _cimg_lanczos(t),
                    w3 = _cimg_lanczos(t - 1),
                    w4 = _cimg_lanczos(t - 2),
                    val2 = (double)*ptrs,
                    val1 = ptrs>=ptrsmin?(double)*(ptrs - sxy):val2,
                    val0 = ptrs>ptrsmin?(double)*(ptrs - 2*sxy):val1,
                    val3 = ptrs<=ptrsmax?(double)*(ptrs + sxy):val2,
                    val4 = ptrs<ptrsmax?(double)*(ptrs + 2*sxy):val3,
                    val = (val0*w0 + val1*w1 + val2*w2 + val3*w3 + val4*w4)/(w1 + w2 + w3 + w4);
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sxy;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resy.assign();
        } else resz.assign(resy,true);

        if (sc!=_spectrum) {
          if (_spectrum==1) resz.get_resize(sx,sy,sz,sc,1).move_to(resc);
          else {
            if (_spectrum>sc) resz.get_resize(sx,sy,sz,sc,2).move_to(resc);
            else {
              const double fc = (!boundary_conditions && sc>_spectrum)?(sc>1?(_spectrum - 1.)/(sc - 1):0):
                (double)_spectrum/sc;
              const unsigned int sxyz = sx*sy*sz;
              resc.assign(sx,sy,sz,sc);
              curr = old = 0;
              {
                unsigned int *poff = off._data;
                double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  *(pfoff++) = curr - (unsigned int)curr;
                  old = curr;
                  curr = std::min(spectrum() - 1.,curr + fc);
                  *(poff++) = sxyz*((unsigned int)curr - (unsigned int)old);
                }
              }
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                                 cimg_openmp_if(resc._spectrum>=256 && resc._width*resc._height*resc._depth>=256))
              cimg_forXYZ(resc,x,y,z) {
                const T *const ptrs0 = resz.data(x,y,z,0), *ptrs = ptrs0, *const ptrsmin = ptrs0 + sxyz,
                  *const ptrsmax = ptrs + (_spectrum - 2)*sxyz;
                T *ptrd = resc.data(x,y,z,0);
                const unsigned int *poff = off._data;
                const double *pfoff = foff._data;
                cimg_forC(resc,c) {
                  const double
                    t = *(pfoff++),
                    w0 = _cimg_lanczos(t + 2),
                    w1 = _cimg_lanczos(t + 1),
                    w2 = _cimg_lanczos(t),
                    w3 = _cimg_lanczos(t - 1),
                    w4 = _cimg_lanczos(t - 2),
                    val2 = (double)*ptrs,
                    val1 = ptrs>=ptrsmin?(double)*(ptrs - sxyz):val2,
                    val0 = ptrs>ptrsmin?(double)*(ptrs - 2*sxyz):val1,
                    val3 = ptrs<=ptrsmax?(double)*(ptrs + sxyz):val2,
                    val4 = ptrs<ptrsmax?(double)*(ptrs + 2*sxyz):val3,
                    val = (val0*w0 + val1*w1 + val2*w2 + val3*w3 + val4*w4)/(w1 + w2 + w3 + w4);
                  *ptrd = (T)(val<vmin?vmin:val>vmax?vmax:val);
                  ptrd+=sxyz;
                  ptrs+=*(poff++);
                }
              }
            }
          }
          resz.assign();
        } else resc.assign(resz,true);

        return resc._is_shared?(resz._is_shared?(resy._is_shared?(resx._is_shared?(+(*this)):resx):resy):resz):resc;
      } break;

        // Unknown interpolation.
        //
      default :
        throw CImgArgumentException(_cimg_instance
                                    "resize(): Invalid specified interpolation %d "
                                    "(should be { -1=raw | 0=none | 1=nearest | 2=average | 3=linear | 4=grid | "
                                    "5=cubic | 6=lanczos }).",
                                    cimg_instance,
                                    interpolation_type);
      }
      return res;
    }

    //! Resize image to dimensions of another image.
    /**
       \param src Reference image used for dimensions.
       \param interpolation_type Interpolation method.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param centering_x Set centering type (only if \p interpolation_type=0).
       \param centering_y Set centering type (only if \p interpolation_type=0).
       \param centering_z Set centering type (only if \p interpolation_type=0).
       \param centering_c Set centering type (only if \p interpolation_type=0).
     **/
    template<typename t>
    CImg<T>& resize(const CImg<t>& src,
                    const int interpolation_type=1, const unsigned int boundary_conditions=0,
                    const float centering_x = 0, const float centering_y = 0,
                    const float centering_z = 0, const float centering_c = 0) {
      return resize(src._width,src._height,src._depth,src._spectrum,interpolation_type,boundary_conditions,
                    centering_x,centering_y,centering_z,centering_c);
    }

    //! Resize image to dimensions of another image \newinstance.
    template<typename t>
    CImg<T> get_resize(const CImg<t>& src,
                       const int interpolation_type=1, const unsigned int boundary_conditions=0,
                       const float centering_x = 0, const float centering_y = 0,
                       const float centering_z = 0, const float centering_c = 0) const {
      return get_resize(src._width,src._height,src._depth,src._spectrum,interpolation_type,boundary_conditions,
                        centering_x,centering_y,centering_z,centering_c);
    }

    //! Resize image to dimensions of a display window.
    /**
       \param disp Reference display window used for dimensions.
       \param interpolation_type Interpolation method.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param centering_x Set centering type (only if \p interpolation_type=0).
       \param centering_y Set centering type (only if \p interpolation_type=0).
       \param centering_z Set centering type (only if \p interpolation_type=0).
       \param centering_c Set centering type (only if \p interpolation_type=0).
     **/
    CImg<T>& resize(const CImgDisplay& disp,
                    const int interpolation_type=1, const unsigned int boundary_conditions=0,
                    const float centering_x = 0, const float centering_y = 0,
                    const float centering_z = 0, const float centering_c = 0) {
      return resize(disp.width(),disp.height(),_depth,_spectrum,interpolation_type,boundary_conditions,
                    centering_x,centering_y,centering_z,centering_c);
    }

    //! Resize image to dimensions of a display window \newinstance.
    CImg<T> get_resize(const CImgDisplay& disp,
                       const int interpolation_type=1, const unsigned int boundary_conditions=0,
                       const float centering_x = 0, const float centering_y = 0,
                       const float centering_z = 0, const float centering_c = 0) const {
      return get_resize(disp.width(),disp.height(),_depth,_spectrum,interpolation_type,boundary_conditions,
                        centering_x,centering_y,centering_z,centering_c);
    }

    //! Resize image to double-size, using the Scale2X algorithm.
    /**
       \note Use anisotropic upscaling algorithm
       <a href="http://scale2x.sourceforge.net/algorithm.html">described here</a>.
    **/
    CImg<T>& resize_doubleXY() {
      return get_resize_doubleXY().move_to(*this);
    }

    //! Resize image to double-size, using the Scale2X algorithm \newinstance.
    CImg<T> get_resize_doubleXY() const {
#define _cimg_gs2x_for3(bound,i) \
 for (int i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1; \
      _n1##i<(int)(bound) || i==--_n1##i; \
      _p1##i = i++, ++_n1##i, ptrd1+=(res)._width, ptrd2+=(res)._width)

#define _cimg_gs2x_for3x3(img,x,y,z,c,I,T) \
  _cimg_gs2x_for3((img)._height,y) for (int x = 0, \
   _p1##x = 0, \
   _n1##x = (int)( \
   (I[1] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[3] = I[4] = (T)(img)(0,y,z,c)), \
   (I[7] = (T)(img)(0,_n1##y,z,c)),     \
   1>=(img)._width?(img).width() - 1:1); \
   (_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x; \
   I[1] = I[2], \
   I[3] = I[4], I[4] = I[5], \
   I[7] = I[8], \
   _p1##x = x++, ++_n1##x)

      if (is_empty()) return *this;
      CImg<T> res(_width<<1,_height<<1,_depth,_spectrum);
      CImg_3x3(I,T);
      cimg_forZC(*this,z,c) {
        T
          *ptrd1 = res.data(0,0,z,c),
          *ptrd2 = ptrd1 + res._width;
        _cimg_gs2x_for3x3(*this,x,y,z,c,I,T) {
          if (Icp!=Icn && Ipc!=Inc) {
            *(ptrd1++) = Ipc==Icp?Ipc:Icc;
            *(ptrd1++) = Icp==Inc?Inc:Icc;
            *(ptrd2++) = Ipc==Icn?Ipc:Icc;
            *(ptrd2++) = Icn==Inc?Inc:Icc;
          } else { *(ptrd1++) = Icc; *(ptrd1++) = Icc; *(ptrd2++) = Icc; *(ptrd2++) = Icc; }
        }
      }
      return res;
    }

    //! Resize image to triple-size, using the Scale3X algorithm.
    /**
       \note Use anisotropic upscaling algorithm
       <a href="http://scale2x.sourceforge.net/algorithm.html">described here</a>.
    **/
    CImg<T>& resize_tripleXY() {
      return get_resize_tripleXY().move_to(*this);
    }

    //! Resize image to triple-size, using the Scale3X algorithm \newinstance.
    CImg<T> get_resize_tripleXY() const {
#define _cimg_gs3x_for3(bound,i) \
 for (int i = 0, _p1##i = 0, \
      _n1##i = 1>=(bound)?(int)(bound) - 1:1; \
      _n1##i<(int)(bound) || i==--_n1##i; \
      _p1##i = i++, ++_n1##i, ptrd1+=2*(res)._width, ptrd2+=2*(res)._width, ptrd3+=2*(res)._width)

#define _cimg_gs3x_for3x3(img,x,y,z,c,I,T) \
  _cimg_gs3x_for3((img)._height,y) for (int x = 0, \
   _p1##x = 0, \
   _n1##x = (int)( \
   (I[0] = I[1] = (T)(img)(_p1##x,_p1##y,z,c)), \
   (I[3] = I[4] = (T)(img)(0,y,z,c)), \
   (I[6] = I[7] = (T)(img)(0,_n1##y,z,c)),      \
   1>=(img)._width?(img).width() - 1:1); \
   (_n1##x<(img).width() && ( \
   (I[2] = (T)(img)(_n1##x,_p1##y,z,c)), \
   (I[5] = (T)(img)(_n1##x,y,z,c)), \
   (I[8] = (T)(img)(_n1##x,_n1##y,z,c)),1)) || \
   x==--_n1##x; \
   I[0] = I[1], I[1] = I[2], \
   I[3] = I[4], I[4] = I[5], \
   I[6] = I[7], I[7] = I[8], \
   _p1##x = x++, ++_n1##x)

      if (is_empty()) return *this;
      CImg<T> res(3*_width,3*_height,_depth,_spectrum);
      CImg_3x3(I,T);
      cimg_forZC(*this,z,c) {
        T
          *ptrd1 = res.data(0,0,z,c),
          *ptrd2 = ptrd1 + res._width,
          *ptrd3 = ptrd2 + res._width;
        _cimg_gs3x_for3x3(*this,x,y,z,c,I,T) {
          if (Icp!=Icn && Ipc!=Inc) {
            *(ptrd1++) = Ipc==Icp?Ipc:Icc;
            *(ptrd1++) = (Ipc==Icp && Icc!=Inp) || (Icp==Inc && Icc!=Ipp)?Icp:Icc;
            *(ptrd1++) = Icp==Inc?Inc:Icc;
            *(ptrd2++) = (Ipc==Icp && Icc!=Ipn) || (Ipc==Icn && Icc!=Ipp)?Ipc:Icc;
            *(ptrd2++) = Icc;
            *(ptrd2++) = (Icp==Inc && Icc!=Inn) || (Icn==Inc && Icc!=Inp)?Inc:Icc;
            *(ptrd3++) = Ipc==Icn?Ipc:Icc;
            *(ptrd3++) = (Ipc==Icn && Icc!=Inn) || (Icn==Inc && Icc!=Ipn)?Icn:Icc;
            *(ptrd3++) = Icn==Inc?Inc:Icc;
          } else {
            *(ptrd1++) = Icc; *(ptrd1++) = Icc; *(ptrd1++) = Icc;
            *(ptrd2++) = Icc; *(ptrd2++) = Icc; *(ptrd2++) = Icc;
            *(ptrd3++) = Icc; *(ptrd3++) = Icc; *(ptrd3++) = Icc;
          }
        }
      }
      return res;
    }

    //! Mirror image content along specified axis.
    /**
       \param axis Mirror axis
    **/
    CImg<T>& mirror(const char axis) {
      if (is_empty()) return *this;
      T *pf, *pb, *buffer = 0;
      switch (cimg::lowercase(axis)) {
      case 'x' : {
        pf = _data; pb = data(_width - 1);
        const unsigned int width2 = _width/2;
        for (unsigned int yzv = 0; yzv<_height*_depth*_spectrum; ++yzv) {
          for (unsigned int x = 0; x<width2; ++x) { const T val = *pf; *(pf++) = *pb; *(pb--) = val; }
          pf+=_width - width2;
          pb+=_width + width2;
        }
      } break;
      case 'y' : {
        CImg<T> _buffer(_width);
        buffer = _buffer._data;
        pf = _data; pb = data(0,_height - 1);
        const unsigned int height2 = _height/2;
        for (unsigned int zv = 0; zv<_depth*_spectrum; ++zv) {
          for (unsigned int y = 0; y<height2; ++y) {
            std::memcpy(buffer,pf,_width*sizeof(T));
            std::memcpy(pf,pb,_width*sizeof(T));
            std::memcpy(pb,buffer,_width*sizeof(T));
            pf+=_width;
            pb-=_width;
          }
          pf+=(ulongT)_width*(_height - height2);
          pb+=(ulongT)_width*(_height + height2);
        }
      } break;
      case 'z' : {
        CImg<T> _buffer(_width,_height);
        buffer = _buffer._data;
        pf = _data; pb = data(0,0,_depth - 1);
        const unsigned int depth2 = _depth/2;
        cimg_forC(*this,c) {
          for (unsigned int z = 0; z<depth2; ++z) {
            std::memcpy(buffer,pf,_width*_height*sizeof(T));
            std::memcpy(pf,pb,_width*_height*sizeof(T));
            std::memcpy(pb,buffer,_width*_height*sizeof(T));
            pf+=(ulongT)_width*_height;
            pb-=(ulongT)_width*_height;
          }
          pf+=(ulongT)_width*_height*(_depth - depth2);
          pb+=(ulongT)_width*_height*(_depth + depth2);
        }
      } break;
      case 'c' : {
        CImg<T> _buffer(_width,_height,_depth);
        buffer = _buffer._data;
        pf = _data; pb = data(0,0,0,_spectrum - 1);
        const unsigned int _spectrum2 = _spectrum/2;
        for (unsigned int v = 0; v<_spectrum2; ++v) {
          std::memcpy(buffer,pf,_width*_height*_depth*sizeof(T));
          std::memcpy(pf,pb,_width*_height*_depth*sizeof(T));
          std::memcpy(pb,buffer,_width*_height*_depth*sizeof(T));
          pf+=(ulongT)_width*_height*_depth;
          pb-=(ulongT)_width*_height*_depth;
        }
      } break;
      default :
        throw CImgArgumentException(_cimg_instance
                                    "mirror(): Invalid specified axis '%c'.",
                                    cimg_instance,
                                    axis);
      }
      return *this;
    }

    //! Mirror image content along specified axis \newinstance.
    CImg<T> get_mirror(const char axis) const {
      return (+*this).mirror(axis);
    }

    //! Mirror image content along specified axes.
    /**
       \param axes Mirror axes, as a C-string.
       \note \c axes may contains multiple characters, e.g. \c "xyz"
    **/
    CImg<T>& mirror(const char *const axes) {
      for (const char *s = axes; *s; ++s) mirror(*s);
      return *this;
    }

    //! Mirror image content along specified axes \newinstance.
    CImg<T> get_mirror(const char *const axes) const {
      return (+*this).mirror(axes);
    }

    //! Shift the image content.
    /**
       \param delta_x Amount of displacement along the X-axis.
       \param delta_y Amount of displacement along the Y-axis.
       \param delta_z Amount of displacement along the Z-axis.
       \param delta_c Amount of displacement along the C-axis.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
    **/
    CImg<T>& shift(const int delta_x, const int delta_y=0, const int delta_z=0, const int delta_c=0,
                   const unsigned int boundary_conditions=0) {
      if (is_empty() || (!delta_x && !delta_y && !delta_z && !delta_c)) return *this;
      if (boundary_conditions==3)
        return get_crop(-delta_x,-delta_y,-delta_z,-delta_c,
                        width() - delta_x - 1,
                        height() - delta_y - 1,
                        depth() - delta_z - 1,
                        spectrum() - delta_c - 1,3).move_to(*this);
      if (delta_x) // Shift along X-axis
        switch (boundary_conditions) {
        case 2 : { // Periodic
          const int ml = cimg::mod(-delta_x,width()), ndelta_x = (ml<=width()/2)?ml:(ml-width());
          if (!ndelta_x) return *this;
          CImg<T> buf(cimg::abs(ndelta_x));
          if (ndelta_x>0) cimg_forYZC(*this,y,z,c) {
              std::memcpy(buf,data(0,y,z,c),ndelta_x*sizeof(T));
              std::memmove(data(0,y,z,c),data(ndelta_x,y,z,c),(_width-ndelta_x)*sizeof(T));
              std::memcpy(data(_width-ndelta_x,y,z,c),buf,ndelta_x*sizeof(T));
            } else cimg_forYZC(*this,y,z,c) {
              std::memcpy(buf,data(_width + ndelta_x,y,z,c),-ndelta_x*sizeof(T));
              std::memmove(data(-ndelta_x,y,z,c),data(0,y,z,c),(_width + ndelta_x)*sizeof(T));
              std::memcpy(data(0,y,z,c),buf,-ndelta_x*sizeof(T));
            }
        } break;
        case 1 : // Neumann
          if (delta_x<0) {
            const int ndelta_x = (-delta_x>=width())?width() - 1:-delta_x;
            if (!ndelta_x) return *this;
            cimg_forYZC(*this,y,z,c) {
              std::memmove(data(0,y,z,c),data(ndelta_x,y,z,c),(_width-ndelta_x)*sizeof(T));
              T *ptrd = data(_width - 1,y,z,c);
              const T val = *ptrd;
              for (int l = 0; l<ndelta_x - 1; ++l) *(--ptrd) = val;
            }
          } else {
            const int ndelta_x = (delta_x>=width())?width() - 1:delta_x;
            if (!ndelta_x) return *this;
            cimg_forYZC(*this,y,z,c) {
              std::memmove(data(ndelta_x,y,z,c),data(0,y,z,c),(_width-ndelta_x)*sizeof(T));
              T *ptrd = data(0,y,z,c);
              const T val = *ptrd;
              for (int l = 0; l<ndelta_x - 1; ++l) *(++ptrd) = val;
            }
          }
          break;
        default : // Dirichlet
          if (delta_x<=-width() || delta_x>=width()) return fill((T)0);
          if (delta_x<0) cimg_forYZC(*this,y,z,c) {
              std::memmove(data(0,y,z,c),data(-delta_x,y,z,c),(_width + delta_x)*sizeof(T));
              std::memset(data(_width + delta_x,y,z,c),0,-delta_x*sizeof(T));
            } else cimg_forYZC(*this,y,z,c) {
              std::memmove(data(delta_x,y,z,c),data(0,y,z,c),(_width-delta_x)*sizeof(T));
              std::memset(data(0,y,z,c),0,delta_x*sizeof(T));
            }
        }

      if (delta_y) // Shift along Y-axis
        switch (boundary_conditions) {
        case 2 : { // Periodic
          const int ml = cimg::mod(-delta_y,height()), ndelta_y = (ml<=height()/2)?ml:(ml-height());
          if (!ndelta_y) return *this;
          CImg<T> buf(width(),cimg::abs(ndelta_y));
          if (ndelta_y>0) cimg_forZC(*this,z,c) {
              std::memcpy(buf,data(0,0,z,c),_width*ndelta_y*sizeof(T));
              std::memmove(data(0,0,z,c),data(0,ndelta_y,z,c),_width*(_height-ndelta_y)*sizeof(T));
              std::memcpy(data(0,_height-ndelta_y,z,c),buf,_width*ndelta_y*sizeof(T));
            } else cimg_forZC(*this,z,c) {
              std::memcpy(buf,data(0,_height + ndelta_y,z,c),-ndelta_y*_width*sizeof(T));
              std::memmove(data(0,-ndelta_y,z,c),data(0,0,z,c),_width*(_height + ndelta_y)*sizeof(T));
              std::memcpy(data(0,0,z,c),buf,-ndelta_y*_width*sizeof(T));
            }
        } break;
        case 1 : // Neumann
          if (delta_y<0) {
            const int ndelta_y = (-delta_y>=height())?height() - 1:-delta_y;
            if (!ndelta_y) return *this;
            cimg_forZC(*this,z,c) {
              std::memmove(data(0,0,z,c),data(0,ndelta_y,z,c),_width*(_height-ndelta_y)*sizeof(T));
              T *ptrd = data(0,_height-ndelta_y,z,c), *ptrs = data(0,_height - 1,z,c);
              for (int l = 0; l<ndelta_y - 1; ++l) { std::memcpy(ptrd,ptrs,_width*sizeof(T)); ptrd+=_width; }
            }
          } else {
            const int ndelta_y = (delta_y>=height())?height() - 1:delta_y;
            if (!ndelta_y) return *this;
            cimg_forZC(*this,z,c) {
              std::memmove(data(0,ndelta_y,z,c),data(0,0,z,c),_width*(_height-ndelta_y)*sizeof(T));
              T *ptrd = data(0,1,z,c), *ptrs = data(0,0,z,c);
              for (int l = 0; l<ndelta_y - 1; ++l) { std::memcpy(ptrd,ptrs,_width*sizeof(T)); ptrd+=_width; }
            }
          }
          break;
        default : // Dirichlet
          if (delta_y<=-height() || delta_y>=height()) return fill((T)0);
          if (delta_y<0) cimg_forZC(*this,z,c) {
              std::memmove(data(0,0,z,c),data(0,-delta_y,z,c),_width*(_height + delta_y)*sizeof(T));
              std::memset(data(0,_height + delta_y,z,c),0,-delta_y*_width*sizeof(T));
            } else cimg_forZC(*this,z,c) {
              std::memmove(data(0,delta_y,z,c),data(0,0,z,c),_width*(_height-delta_y)*sizeof(T));
              std::memset(data(0,0,z,c),0,delta_y*_width*sizeof(T));
            }
        }

      if (delta_z) // Shift along Z-axis
        switch (boundary_conditions) {
        case 2 : { // Periodic
          const int ml = cimg::mod(-delta_z,depth()), ndelta_z = (ml<=depth()/2)?ml:(ml-depth());
          if (!ndelta_z) return *this;
          CImg<T> buf(width(),height(),cimg::abs(ndelta_z));
          if (ndelta_z>0) cimg_forC(*this,c) {
              std::memcpy(buf,data(0,0,0,c),_width*_height*ndelta_z*sizeof(T));
              std::memmove(data(0,0,0,c),data(0,0,ndelta_z,c),_width*_height*(_depth-ndelta_z)*sizeof(T));
              std::memcpy(data(0,0,_depth-ndelta_z,c),buf,_width*_height*ndelta_z*sizeof(T));
            } else cimg_forC(*this,c) {
              std::memcpy(buf,data(0,0,_depth + ndelta_z,c),-ndelta_z*_width*_height*sizeof(T));
              std::memmove(data(0,0,-ndelta_z,c),data(0,0,0,c),_width*_height*(_depth + ndelta_z)*sizeof(T));
              std::memcpy(data(0,0,0,c),buf,-ndelta_z*_width*_height*sizeof(T));
            }
        } break;
        case 1 : // Neumann
          if (delta_z<0) {
            const int ndelta_z = (-delta_z>=depth())?depth() - 1:-delta_z;
            if (!ndelta_z) return *this;
            cimg_forC(*this,c) {
              std::memmove(data(0,0,0,c),data(0,0,ndelta_z,c),_width*_height*(_depth-ndelta_z)*sizeof(T));
              T *ptrd = data(0,0,_depth-ndelta_z,c), *ptrs = data(0,0,_depth - 1,c);
              for (int l = 0; l<ndelta_z - 1; ++l) {
                std::memcpy(ptrd,ptrs,_width*_height*sizeof(T)); ptrd+=(ulongT)_width*_height;
              }
            }
          } else {
            const int ndelta_z = (delta_z>=depth())?depth() - 1:delta_z;
            if (!ndelta_z) return *this;
            cimg_forC(*this,c) {
              std::memmove(data(0,0,ndelta_z,c),data(0,0,0,c),_width*_height*(_depth-ndelta_z)*sizeof(T));
              T *ptrd = data(0,0,1,c), *ptrs = data(0,0,0,c);
              for (int l = 0; l<ndelta_z - 1; ++l) {
                std::memcpy(ptrd,ptrs,_width*_height*sizeof(T)); ptrd+=(ulongT)_width*_height;
              }
            }
          }
          break;
        default : // Dirichlet
          if (delta_z<=-depth() || delta_z>=depth()) return fill((T)0);
          if (delta_z<0) cimg_forC(*this,c) {
              std::memmove(data(0,0,0,c),data(0,0,-delta_z,c),_width*_height*(_depth + delta_z)*sizeof(T));
              std::memset(data(0,0,_depth + delta_z,c),0,_width*_height*(-delta_z)*sizeof(T));
            } else cimg_forC(*this,c) {
              std::memmove(data(0,0,delta_z,c),data(0,0,0,c),_width*_height*(_depth-delta_z)*sizeof(T));
              std::memset(data(0,0,0,c),0,delta_z*_width*_height*sizeof(T));
            }
        }

      if (delta_c) // Shift along C-axis
        switch (boundary_conditions) {
        case 2 : { // Periodic
          const int ml = cimg::mod(-delta_c,spectrum()), ndelta_c = (ml<=spectrum()/2)?ml:(ml-spectrum());
          if (!ndelta_c) return *this;
          CImg<T> buf(width(),height(),depth(),cimg::abs(ndelta_c));
          if (ndelta_c>0) {
            std::memcpy(buf,_data,_width*_height*_depth*ndelta_c*sizeof(T));
            std::memmove(_data,data(0,0,0,ndelta_c),_width*_height*_depth*(_spectrum-ndelta_c)*sizeof(T));
            std::memcpy(data(0,0,0,_spectrum-ndelta_c),buf,_width*_height*_depth*ndelta_c*sizeof(T));
          } else {
            std::memcpy(buf,data(0,0,0,_spectrum + ndelta_c),-ndelta_c*_width*_height*_depth*sizeof(T));
            std::memmove(data(0,0,0,-ndelta_c),_data,_width*_height*_depth*(_spectrum + ndelta_c)*sizeof(T));
            std::memcpy(_data,buf,-ndelta_c*_width*_height*_depth*sizeof(T));
          }
        } break;
        case 1 : // Neumann
          if (delta_c<0) {
            const int ndelta_c = (-delta_c>=spectrum())?spectrum() - 1:-delta_c;
            if (!ndelta_c) return *this;
            std::memmove(_data,data(0,0,0,ndelta_c),_width*_height*_depth*(_spectrum-ndelta_c)*sizeof(T));
            T *ptrd = data(0,0,0,_spectrum-ndelta_c), *ptrs = data(0,0,0,_spectrum - 1);
            for (int l = 0; l<ndelta_c - 1; ++l) {
              std::memcpy(ptrd,ptrs,_width*_height*_depth*sizeof(T)); ptrd+=(ulongT)_width*_height*_depth;
            }
          } else {
            const int ndelta_c = (delta_c>=spectrum())?spectrum() - 1:delta_c;
            if (!ndelta_c) return *this;
            std::memmove(data(0,0,0,ndelta_c),_data,_width*_height*_depth*(_spectrum-ndelta_c)*sizeof(T));
            T *ptrd = data(0,0,0,1);
            for (int l = 0; l<ndelta_c - 1; ++l) {
              std::memcpy(ptrd,_data,_width*_height*_depth*sizeof(T)); ptrd+=(ulongT)_width*_height*_depth;
            }
          }
          break;
        default : // Dirichlet
          if (delta_c<=-spectrum() || delta_c>=spectrum()) return fill((T)0);
          if (delta_c<0) {
            std::memmove(_data,data(0,0,0,-delta_c),_width*_height*_depth*(_spectrum + delta_c)*sizeof(T));
            std::memset(data(0,0,0,_spectrum + delta_c),0,_width*_height*_depth*(-delta_c)*sizeof(T));
          } else {
            std::memmove(data(0,0,0,delta_c),_data,_width*_height*_depth*(_spectrum-delta_c)*sizeof(T));
            std::memset(_data,0,delta_c*_width*_height*_depth*sizeof(T));
          }
        }
      return *this;
    }

    //! Shift image content \newinstance.
    CImg<T> get_shift(const int delta_x, const int delta_y=0, const int delta_z=0, const int delta_c=0,
                      const unsigned int boundary_conditions=0) const {
      return (+*this).shift(delta_x,delta_y,delta_z,delta_c,boundary_conditions);
    }

    //! Permute axes order.
    /**
       \param axes_order Axes permutations, as a C-string of 4 characters.
       This function permutes the image content according to the specified axes order.
    **/
    CImg<T>& permute_axes(const char *const axes_order) {
      if (is_empty() || !axes_order) return *this;
      const unsigned uicase = _permute_axes_uicase(axes_order);
      if (_permute_axes_is_optim(uicase)) { // Data layout makes it possible to do nothing but set the new dimensions
        CImg<T> res(*this,true);
        for (unsigned int i = 0; i<4; ++i) {
          const unsigned int
            axis = (uicase>>(4*(3 - i)))&15,
            value = !axis?_width:axis==1?_height:axis==2?_depth:_spectrum;
          if (!i) res._width = value; else if (i==1) res._height = value;
          else if (i==2) res._depth = value; else res._spectrum = value;
        }
        _width = res._width; _height = res._height; _depth = res._depth; _spectrum = res._spectrum;
        return *this;
      }
      return get_permute_axes(axes_order).move_to(*this);
    }

    //! Permute axes order \newinstance.
    CImg<T> get_permute_axes(const char *const axes_order) const {
      const T foo = (T)0;
      return _permute_axes(axes_order,foo);
    }

    unsigned int _permute_axes_uicase(const char *const axes_order) const { // Convert axes to integer case number
      unsigned char s_axes[4] = { 0,1,2,3 }, n_axes[4] = { };
      bool is_error = false;
      if (axes_order) for (unsigned int l = 0; axes_order[l]; ++l) {
          int c = cimg::lowercase(axes_order[l]);
          if (l>=4 || (c!='x' && c!='y' && c!='z' && c!='c')) { is_error = true; break; }
          else { ++n_axes[c%=4]; s_axes[l] = (unsigned char)c; }
        }
      is_error|=(*n_axes>1) || (n_axes[1]>1) || (n_axes[2]>1) || (n_axes[3]>1);
      if (is_error)
        throw CImgArgumentException(_cimg_instance
                                    "permute_axes(): Invalid specified axes order '%s'.",
                                    cimg_instance,
                                    axes_order);
      return (s_axes[0]<<12) | (s_axes[1]<<8) | (s_axes[2]<<4) | (s_axes[3]);
    }

    bool _permute_axes_is_optim(const unsigned int uicase) const { // Determine cases where nothing has to be done
      const unsigned int co = ((_width>1)<<3)|((_height>1)<<2)|((_depth>1)<<1)|(_spectrum>1);
      if (co<=2 || uicase==0x0123) return true;
      switch (uicase) {
      case (0x0132) : if ((co>=4 && co<=6) || (co>=8 && co<=10) || (co>=12 && co<=14)) return true; break;
      case (0x0213) : if ((co>=3 && co<=5) || (co>=8 && co<=13)) return true; break;
      case (0x0231) : if (co==3 || co==4 || (co>=8 && co<=12)) return true; break;
      case (0x0312) : if (co==4 || co==6 || co==8 || co==9 || co==10 || co==12 || co==14) return true; break;
      case (0x0321) : if (co==4 || (co>=8 && co<=10) || co==12) return true; break;
      case (0x1023) : if (co>=3 && co<=11) return true; break;
      case (0x1032) : if ((co>=4 && co<=6) || (co>=8 && co<=10)) return true; break;
      case (0x1203) : if (co>=3 && co<=9) return true; break;
      case (0x1230) : if (co>=3 && co<=8) return true; break;
      case (0x1302) : if ((co>=4 && co<=6) || co==8 || co==10) return true; break;
      case (0x1320) : if ((co>=4 && co<=6) || co==8) return true; break;
      case (0x2013) : if ((co>=3 && co<=5) || co==8 || co==9 || co==12 || co==13) return true; break;
      case (0x2031) : if (co==3 || co==4 || co==8 || co==9 || co==12) return true; break;
      case (0x2103) : if ((co>=3 && co<=5) || co==8 || co==9) return true; break;
      case (0x2130) : if ((co>=3 && co<=5) || co==8) return true; break;
      case (0x2301) : if (co==3 || co==4 || co==8 || co==12) return true; break;
      case (0x2310) : if (co==3 || co==4 || co==8) return true; break;
      case (0x3012) : if (co==4 || co==6 || co==8 || co==10 || co==12 || co==14) return true; break;
      case (0x3021) : if (co==4 || co==8 || co==10 || co==12) return true; break;
      case (0x3102) : if (co==4 || co==6 || co==8 || co==10) return true; break;
      case (0x3120) : if (co==4 || co==6 || co==8) return true; break;
      case (0x3201) : if (co==4 || co==8 || co==12) return true; break;
      case (0x3210) : if (co==4 || co==8) return true; break;
      }
      return false;
    }

    template<typename t>
    CImg<t> _permute_axes(const char *const axes_order, const t&) const {
      if (is_empty() || !axes_order) return CImg<t>(*this,false);
      CImg<t> res;
      const unsigned uicase = _permute_axes_uicase(axes_order);

      if (_permute_axes_is_optim(uicase)) { // Data layout makes it possible to do nothing but set the new dimensions
        res.assign(*this,false);
        for (unsigned int i = 0; i<4; ++i) {
          const unsigned int
            axis = (uicase>>(4*(3 - i)))&15,
            value = !axis?_width:axis==1?_height:axis==2?_depth:_spectrum;
          if (!i) res._width = value; else if (i==1) res._height = value;
          else if (i==2) res._depth = value; else res._spectrum = value;
        }
        return res;
      }

      const T* ptrs = _data;
      ulongT wh, whd;

      switch (uicase) {
      case 0x0123 : // xyzc
        return +*this;
      case 0x0132 : // xycz
        res.assign(_width,_height,_spectrum,_depth);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(x,y,c,z,wh,whd) = (t)*(ptrs++);
        break;
      case 0x0213 : // xzyc
        res.assign(_width,_depth,_height,_spectrum);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(x,z,y,c,wh,whd) = (t)*(ptrs++);
        break;
      case 0x0231 : // xzcy
        res.assign(_width,_depth,_spectrum,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(x,z,c,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x0312 : // xcyz
        res.assign(_width,_spectrum,_height,_depth);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(x,c,y,z,wh,whd) = (t)*(ptrs++);
        break;
      case 0x0321 : // xczy
        res.assign(_width,_spectrum,_depth,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(x,c,z,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x1023 : // yxzc
        res.assign(_height,_width,_depth,_spectrum);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(y,x,z,c,wh,whd) = (t)*(ptrs++);
        break;
      case 0x1032 : // yxcz
        res.assign(_height,_width,_spectrum,_depth);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(y,x,c,z,wh,whd) = (t)*(ptrs++);
        break;
      case 0x1203 : // yzxc
        res.assign(_height,_depth,_width,_spectrum);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(y,z,x,c,wh,whd) = (t)*(ptrs++);
        break;
      case 0x1230 : // yzcx
        res.assign(_height,_depth,_spectrum,_width);
        switch (_width) {
        case 1 : {
          t *ptr_r = res.data(0,0,0,0);
          for (unsigned int siz = _height*_depth*_spectrum; siz; --siz) {
            *(ptr_r++) = (t)*(ptrs++);
          }
        } break;
        case 2 : {
          t *ptr_r = res.data(0,0,0,0), *ptr_g = res.data(0,0,0,1);
          for (unsigned int siz = _height*_depth*_spectrum; siz; --siz) {
            *(ptr_r++) = (t)ptrs[0];
            *(ptr_g++) = (t)ptrs[1];
            ptrs+=2;
          }
        } break;
        case 3 : { // Optimization for the classical conversion from interleaved RGB to planar RGB
          t *ptr_r = res.data(0,0,0,0), *ptr_g = res.data(0,0,0,1), *ptr_b = res.data(0,0,0,2);
          for (unsigned int siz = _height*_depth*_spectrum; siz; --siz) {
            *(ptr_r++) = (t)ptrs[0];
            *(ptr_g++) = (t)ptrs[1];
            *(ptr_b++) = (t)ptrs[2];
            ptrs+=3;
          }
        } break;
        case 4 : { // Optimization for the classical conversion from interleaved RGBA to planar RGBA
          t
            *ptr_r = res.data(0,0,0,0), *ptr_g = res.data(0,0,0,1),
            *ptr_b = res.data(0,0,0,2), *ptr_a = res.data(0,0,0,3);
          for (unsigned int siz = _height*_depth*_spectrum; siz; --siz) {
            *(ptr_r++) = (t)ptrs[0];
            *(ptr_g++) = (t)ptrs[1];
            *(ptr_b++) = (t)ptrs[2];
            *(ptr_a++) = (t)ptrs[3];
            ptrs+=4;
          }
        } break;
        default : {
          wh = (ulongT)res._width*res._height; whd = wh*res._depth;
          cimg_forXYZC(*this,x,y,z,c) res(y,z,c,x,wh,whd) = *(ptrs++);
          return res;
        }
        }
        break;
      case 0x1302 : // ycxz
        res.assign(_height,_spectrum,_width,_depth);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(y,c,x,z,wh,whd) = (t)*(ptrs++);
        break;
      case 0x1320 : // yczx
        res.assign(_height,_spectrum,_depth,_width);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(y,c,z,x,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2013 : // zxyc
        res.assign(_depth,_width,_height,_spectrum);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,x,y,c,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2031 : // zxcy
        res.assign(_depth,_width,_spectrum,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,x,c,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2103 : // zyxc
        res.assign(_depth,_height,_width,_spectrum);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,y,x,c,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2130 : // zycx
        res.assign(_depth,_height,_spectrum,_width);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,y,c,x,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2301 : // zcxy
        res.assign(_depth,_spectrum,_width,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,c,x,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x2310 : // zcyx
        res.assign(_depth,_spectrum,_height,_width);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(z,c,y,x,wh,whd) = (t)*(ptrs++);
        break;
      case 0x3012 : // cxyz
        res.assign(_spectrum,_width,_height,_depth);
        switch (_spectrum) {
        case 1 : {
          const T *ptr_r = data(0,0,0,0);
          t *ptrd = res._data;
          for (ulongT siz = (ulongT)_width*_height*_depth; siz; --siz) *(ptrd++) = (t)*(ptr_r++);
        } break;
        case 2 : {
          const T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1);
          t *ptrd = res._data;
          for (ulongT siz = (ulongT)_width*_height*_depth; siz; --siz) {
            ptrd[0] = (t)*(ptr_r++);
            ptrd[1] = (t)*(ptr_g++);
            ptrd+=2;
          }
        } break;
        case 3 : { // Optimization for the classical conversion from planar RGB to interleaved RGB
          const T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2);
          t *ptrd = res._data;
          for (ulongT siz = (ulongT)_width*_height*_depth; siz; --siz) {
            ptrd[0] = (t)*(ptr_r++);
            ptrd[1] = (t)*(ptr_g++);
            ptrd[2] = (t)*(ptr_b++);
            ptrd+=3;
          }
        } break;
        case 4 : { // Optimization for the classical conversion from planar RGBA to interleaved RGBA
          const T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2), *ptr_a = data(0,0,0,3);
          t *ptrd = res._data;
          for (ulongT siz = (ulongT)_width*_height*_depth; siz; --siz) {
            ptrd[0] = (t)*(ptr_r++);
            ptrd[1] = (t)*(ptr_g++);
            ptrd[2] = (t)*(ptr_b++);
            ptrd[3] = (t)*(ptr_a++);
            ptrd+=4;
          }
        } break;
        default : {
          wh = (ulongT)res._width*res._height; whd = wh*res._depth;
          cimg_forXYZC(*this,x,y,z,c) res(c,x,y,z,wh,whd) = (t)*(ptrs++);
        }
        }
        break;
      case 0x3021 : // cxzy
        res.assign(_spectrum,_width,_depth,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(c,x,z,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x3102 : // cyxz
        res.assign(_spectrum,_height,_width,_depth);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(c,y,x,z,wh,whd) = (t)*(ptrs++);
        break;
      case 0x3120 : // cyzx
        res.assign(_spectrum,_height,_depth,_width);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(c,y,z,x,wh,whd) = (t)*(ptrs++);
        break;
      case 0x3201 : // czxy
        res.assign(_spectrum,_depth,_width,_height);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(c,z,x,y,wh,whd) = (t)*(ptrs++);
        break;
      case 0x3210 : // czyx
        res.assign(_spectrum,_depth,_height,_width);
        wh = (ulongT)res._width*res._height; whd = wh*res._depth;
        cimg_forXYZC(*this,x,y,z,c) res(c,z,y,x,wh,whd) = (t)*(ptrs++);
        break;
      }
      return res;
    }

    //! Unroll pixel values along the specified axis.
    /**
       \param axis Unroll axis (can be \c 'x', \c 'y', \c 'z' or c 'c').
    **/
    CImg<T>& unroll(const char axis) {
      const unsigned int siz = (unsigned int)size();
      if (siz) switch (cimg::lowercase(axis)) {
      case 'x' : _width = siz; _height = _depth = _spectrum = 1; break;
      case 'y' : _height = siz; _width = _depth = _spectrum = 1; break;
      case 'z' : _depth = siz; _width = _height = _spectrum = 1; break;
      case 'c' : _spectrum = siz; _width = _height = _depth = 1; break;
      }
      return *this;
    }

    //! Unroll pixel values along specified axis \newinstance.
    CImg<T> get_unroll(const char axis) const {
      return (+*this).unroll(axis);
    }

    //! Rotate the image by an arbitrary angle.
    /**
       \param angle Rotation angle, in degrees.
       \param interpolation Type of interpolation. Can be <tt>{ 0=nearest | 1=linear | 2=cubic }</tt>.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \note The size of the image is modified.
    **/
    CImg<T>& rotate(const float angle, const unsigned int interpolation=1,
                    const unsigned int boundary_conditions=0) {
      const float nangle = cimg::mod(angle,360.f);
      if (nangle==0.f) return *this;
      return get_rotate(nangle,interpolation,boundary_conditions).move_to(*this);
    }

    //! Rotate image with arbitrary angle \newinstance.
    CImg<T> get_rotate(const float angle, const unsigned int interpolation=1,
                       const unsigned int boundary_conditions=0) const {
      if (is_empty()) return *this;
      CImg<T> res;
      const float nangle = cimg::mod(angle,360.f);
      if (boundary_conditions!=1 && cimg::mod(nangle,90.f)==0) { // Optimized version for orthogonal angles
        const int wm1 = width() - 1, hm1 = height() - 1;
        const int iangle = (int)nangle/90;
        switch (iangle) {
        case 1 : { // 90 deg
          res.assign(_height,_width,_depth,_spectrum);
          T *ptrd = res._data;
          cimg_forXYZC(res,x,y,z,c) *(ptrd++) = (*this)(y,hm1 - x,z,c);
        } break;
        case 2 : { // 180 deg
          res.assign(_width,_height,_depth,_spectrum);
          T *ptrd = res._data;
          cimg_forXYZC(res,x,y,z,c) *(ptrd++) = (*this)(wm1 - x,hm1 - y,z,c);
        } break;
        case 3 : { // 270 deg
          res.assign(_height,_width,_depth,_spectrum);
          T *ptrd = res._data;
          cimg_forXYZC(res,x,y,z,c) *(ptrd++) = (*this)(wm1 - y,x,z,c);
        } break;
        default : // 0 deg
          return *this;
        }
      } else { // Generic angle
        const float
          rad = (float)(nangle*cimg::PI/180.),
          ca = (float)std::cos(rad), sa = (float)std::sin(rad),
          ux = cimg::abs((_width - 1)*ca), uy = cimg::abs((_width - 1)*sa),
          vx = cimg::abs((_height - 1)*sa), vy = cimg::abs((_height - 1)*ca),
          w2 = 0.5f*(_width - 1), h2 = 0.5f*(_height - 1);
        res.assign((int)cimg::round(1 + ux + vx),(int)cimg::round(1 + uy + vy),_depth,_spectrum);
        const float rw2 = 0.5f*(res._width - 1), rh2 = 0.5f*(res._height - 1);
        _rotate(res,nangle,interpolation,boundary_conditions,w2,h2,rw2,rh2);
      }
      return res;
    }

    //! Rotate image with arbitrary angle, around a center point.
    /**
       \param angle Rotation angle, in degrees.
       \param cx X-coordinate of the rotation center.
       \param cy Y-coordinate of the rotation center.
       \param interpolation Type of interpolation, <tt>{ 0=nearest | 1=linear | 2=cubic | 3=mirror }</tt>.
       \param boundary_conditions Boundary conditions, <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
    **/
    CImg<T>& rotate(const float angle, const float cx, const float cy,
                    const unsigned int interpolation, const unsigned int boundary_conditions=0) {
      return get_rotate(angle,cx,cy,interpolation,boundary_conditions).move_to(*this);
    }

    //! Rotate image with arbitrary angle, around a center point \newinstance.
    CImg<T> get_rotate(const float angle, const float cx, const float cy,
                       const unsigned int interpolation, const unsigned int boundary_conditions=0) const {
      if (is_empty()) return *this;
      CImg<T> res(_width,_height,_depth,_spectrum);
      _rotate(res,angle,interpolation,boundary_conditions,cx,cy,cx,cy);
      return res;
    }

    // [internal] Perform 2D rotation with arbitrary angle.
    void _rotate(CImg<T>& res, const float angle,
                 const unsigned int interpolation, const unsigned int boundary_conditions,
                 const float w2, const float h2,
                 const float rw2, const float rh2) const {
      const float
        rad = (float)(angle*cimg::PI/180.),
        ca = (float)std::cos(rad), sa = (float)std::sin(rad);

      switch (boundary_conditions) {
      case 3 : { // Mirror

        switch (interpolation) {
        case 2 : { // Cubic interpolation
          const float ww = 2.f*width(), hh = 2.f*height();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2,
              mx = cimg::mod(w2 + xc*ca + yc*sa,ww),
              my = cimg::mod(h2 - xc*sa + yc*ca,hh);
            res(x,y,z,c) = _cubic_atXY_c(mx<width()?mx:ww - mx - 1,my<height()?my:hh - my - 1,z,c);
          }
        } break;
        case 1 : { // Linear interpolation
          const float ww = 2.f*width(), hh = 2.f*height();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2,
              mx = cimg::mod(w2 + xc*ca + yc*sa,ww),
              my = cimg::mod(h2 - xc*sa + yc*ca,hh);
            res(x,y,z,c) = (T)_linear_atXY(mx<width()?mx:ww - mx - 1,my<height()?my:hh - my - 1,z,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          const int ww = 2*width(), hh = 2*height();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2,
              mx = cimg::mod((int)cimg::round(w2 + xc*ca + yc*sa),ww),
              my = cimg::mod((int)cimg::round(h2 - xc*sa + yc*ca),hh);
            res(x,y,z,c) = (*this)(mx<width()?mx:ww - mx - 1,my<height()?my:hh - my - 1,z,c);
          }
        }
        }
      } break;

      case 2 : // Periodic
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = _cubic_atXY_pc(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = (T)_linear_atXY_p(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = (*this)(cimg::mod((int)cimg::round(w2 + xc*ca + yc*sa),(float)width()),
                                   cimg::mod((int)cimg::round(h2 - xc*sa + yc*ca),(float)height()),z,c);
          }
        }
        } break;

      case 1 : // Neumann
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = _cubic_atXY_c(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = (T)_linear_atXY(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = _atXY((int)cimg::round(w2 + xc*ca + yc*sa),
                                 (int)cimg::round(h2 - xc*sa + yc*ca),z,c);
          }
        }
        } break;

      default : // Dirichlet
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = cubic_atXY_c(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c,(T)0);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = (T)linear_atXY(w2 + xc*ca + yc*sa,h2 - xc*sa + yc*ca,z,c,(T)0);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZC(res,x,y,z,c) {
            const float xc = x - rw2, yc = y - rh2;
            res(x,y,z,c) = atXY((int)cimg::round(w2 + xc*ca + yc*sa),
                                (int)cimg::round(h2 - xc*sa + yc*ca),z,c,(T)0);
          }
        }
        }
      }
    }

    //! Rotate a volumetric image by an arbitrary angle and axis.
    /**
       \param u X-coordinate of the 3D rotation axis.
       \param v Y-coordinate of the 3D rotation axis.
       \param w Z-coordinate of the 3D rotation axis.
       \param angle Rotation angle, in degrees.
       \param interpolation Type of interpolation. Can be <tt>{ 0=nearest | 1=linear | 2=cubic }</tt>.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{  0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \note Most of the time, size of the image is modified.
    **/
    CImg<T> rotate(const float u, const float v, const float w, const float angle,
                   const unsigned int interpolation, const unsigned int boundary_conditions) {
      const float nangle = cimg::mod(angle,360.f);
      if (nangle==0.f) return *this;
      return get_rotate(u,v,w,nangle,interpolation,boundary_conditions).move_to(*this);
    }

    //! Rotate volumetric image with arbitrary angle and axis \newinstance.
    CImg<T> get_rotate(const float u, const float v, const float w, const float angle,
                       const unsigned int interpolation, const unsigned int boundary_conditions) const {
      if (is_empty()) return *this;
      CImg<T> res;
      const float
        w1 = _width - 1, h1 = _height - 1, d1 = _depth -1,
        w2 = 0.5f*w1, h2 = 0.5f*h1, d2 = 0.5f*d1;
      CImg<floatT> R = CImg<floatT>::rotation_matrix(u,v,w,angle);
      const CImg<Tfloat>
        X = R*CImg<Tfloat>(8,3,1,1,
                           0.f,w1,w1,0.f,0.f,w1,w1,0.f,
                           0.f,0.f,h1,h1,0.f,0.f,h1,h1,
                           0.f,0.f,0.f,0.f,d1,d1,d1,d1);
      float
        xm, xM = X.get_shared_row(0).max_min(xm),
        ym, yM = X.get_shared_row(1).max_min(ym),
        zm, zM = X.get_shared_row(2).max_min(zm);
      const int
        dx = (int)cimg::round(xM - xm),
        dy = (int)cimg::round(yM - ym),
        dz = (int)cimg::round(zM - zm);
      R.transpose();
      res.assign(1 + dx,1 + dy,1 + dz,_spectrum);
      const float rw2 = 0.5f*dx, rh2 = 0.5f*dy, rd2 = 0.5f*dz;
      _rotate(res,R,interpolation,boundary_conditions,w2,h2,d2,rw2,rh2,rd2);
      return res;
    }

    //! Rotate volumetric image with arbitrary angle and axis, around a center point.
    /**
       \param u X-coordinate of the 3D rotation axis.
       \param v Y-coordinate of the 3D rotation axis.
       \param w Z-coordinate of the 3D rotation axis.
       \param angle Rotation angle, in degrees.
       \param cx X-coordinate of the rotation center.
       \param cy Y-coordinate of the rotation center.
       \param cz Z-coordinate of the rotation center.
       \param interpolation Type of interpolation. Can be <tt>{ 0=nearest | 1=linear | 2=cubic | 3=mirror }</tt>.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{  0=dirichlet | 1=neumann | 2=periodic }</tt>.
       \note Most of the time, size of the image is modified.
    **/
    CImg<T> rotate(const float u, const float v, const float w, const float angle,
                   const float cx, const float cy, const float cz,
                   const unsigned int interpolation=1, const unsigned int boundary_conditions=0) {
      const float nangle = cimg::mod(angle,360.f);
      if (nangle==0.f) return *this;
      return get_rotate(u,v,w,nangle,cx,cy,cz,interpolation,boundary_conditions).move_to(*this);
    }

    //! Rotate volumetric image with arbitrary angle and axis, around a center point \newinstance.
    CImg<T> get_rotate(const float u, const float v, const float w, const float angle,
                       const float cx, const float cy, const float cz,
                       const unsigned int interpolation=1, const unsigned int boundary_conditions=0) const {
      if (is_empty()) return *this;
      CImg<T> res(_width,_height,_depth,_spectrum);
      CImg<floatT> R = CImg<floatT>::rotation_matrix(u,v,w,-angle);
      _rotate(res,R,interpolation,boundary_conditions,cx,cy,cz,cx,cy,cz);
      return res;
    }

    // [internal] Perform 3D rotation with arbitrary axis and angle.
    void _rotate(CImg<T>& res, const CImg<Tfloat>& R,
                 const unsigned int interpolation, const unsigned int boundary_conditions,
                 const float w2, const float h2, const float d2,
                 const float rw2, const float rh2, const float rd2) const {
      switch (boundary_conditions) {
      case 3 : // Mirror
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          const float ww = 2.f*width(), hh = 2.f*height(), dd = 2.f*depth();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = cimg::mod((float)(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),ww),
              Y = cimg::mod((float)(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),hh),
              Z = cimg::mod((float)(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc),dd);
            cimg_forC(res,c) res(x,y,z,c) = _cubic_atXYZ_c(X<width()?X:ww - X - 1,
                                                           Y<height()?Y:hh - Y - 1,
                                                           Z<depth()?Z:dd - Z - 1,c);
          }
        } break;
        case 1 : { // Linear interpolation
          const float ww = 2.f*width(), hh = 2.f*height(), dd = 2.f*depth();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = cimg::mod((float)(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),ww),
              Y = cimg::mod((float)(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),hh),
              Z = cimg::mod((float)(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc),dd);
            cimg_forC(res,c) res(x,y,z,c) = (T)_linear_atXYZ(X<width()?X:ww - X - 1,
                                                             Y<height()?Y:hh - Y - 1,
                                                             Z<depth()?Z:dd - Z - 1,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          const int ww = 2*width(), hh = 2*height(), dd = 2*depth();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float xc = x - rw2, yc = y - rh2, zc = z - rd2;
            const int
              X = cimg::mod((int)cimg::round(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),ww),
              Y = cimg::mod((int)cimg::round(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),hh),
              Z = cimg::mod((int)cimg::round(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc),dd);
            cimg_forC(res,c) res(x,y,z,c) = (*this)(X<width()?X:ww - X - 1,
                                                    Y<height()?Y:hh - Y - 1,
                                                    Z<depth()?Z:dd - Z -  1,c);
          }
        }
        } break;

      case 2 : // Periodic
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = _cubic_atXYZ_pc(X,Y,Z,c);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = (T)_linear_atXYZ_p(X,Y,Z,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float xc = x - rw2, yc = y - rh2, zc = z - rd2;
            const int
              X = cimg::mod((int)cimg::round(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),width()),
              Y = cimg::mod((int)cimg::round(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),height()),
              Z = cimg::mod((int)cimg::round(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc),depth());
            cimg_forC(res,c) res(x,y,z,c) = (*this)(X,Y,Z,c);
          }
        }
        } break;

      case 1 : // Neumann
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = _cubic_atXYZ_c(X,Y,Z,c);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = _linear_atXYZ(X,Y,Z,c);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float xc = x - rw2, yc = y - rh2, zc = z - rd2;
            const int
              X = (int)cimg::round(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),
              Y = (int)cimg::round(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),
              Z = (int)cimg::round(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc);
            cimg_forC(res,c) res(x,y,z,c) = _atXYZ(X,Y,Z,c);
          }
        }
        } break;

      default : // Dirichlet
        switch (interpolation) {
        case 2 : { // Cubic interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = cubic_atXYZ_c(X,Y,Z,c,(T)0);
          }
        } break;
        case 1 : { // Linear interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float
              xc = x - rw2, yc = y - rh2, zc = z - rd2,
              X = w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc,
              Y = h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc,
              Z = d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc;
            cimg_forC(res,c) res(x,y,z,c) = linear_atXYZ(X,Y,Z,c,(T)0);
          }
        } break;
        default : { // Nearest-neighbor interpolation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(res.size(),2048))
          cimg_forXYZ(res,x,y,z) {
            const float xc = x - rw2, yc = y - rh2, zc = z - rd2;
            const int
              X = (int)cimg::round(w2 + R(0,0)*xc + R(1,0)*yc + R(2,0)*zc),
              Y = (int)cimg::round(h2 + R(0,1)*xc + R(1,1)*yc + R(2,1)*zc),
              Z = (int)cimg::round(d2 + R(0,2)*xc + R(1,2)*yc + R(2,2)*zc);
            cimg_forC(res,c) res(x,y,z,c) = atXYZ(X,Y,Z,c,(T)0);
          }
        }
        } break;
      }
    }

    //! Warp the image content using a warping field.
    /**
       \param p_warp Warping field.
       \param mode Can be { 0=backward-absolute | 1=backward-relative | 2=forward-absolute | 3=forward-relative }
       \param interpolation Can be <tt>{ 0=nearest | 1=linear | 2=cubic }</tt>.
       \param boundary_conditions Boundary conditions <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
    **/
    template<typename t>
    CImg<T>& warp(const CImg<t>& p_warp, const unsigned int mode=0,
                  const unsigned int interpolation=1, const unsigned int boundary_conditions=0) {
      return get_warp(p_warp,mode,interpolation,boundary_conditions).move_to(*this);
    }

    //! Warp image content by a warping field \newinstance.
    template<typename t>
    CImg<T> get_warp(const CImg<t>& p_warp, const unsigned int mode=0,
                     const unsigned int interpolation=1, const unsigned int boundary_conditions=0) const {
      if (is_empty() || !p_warp) return *this;
      if (mode && !is_sameXYZ(p_warp))
        throw CImgArgumentException(_cimg_instance
                                    "warp(): Instance and specified relative warping field (%u,%u,%u,%u,%p) "
                                    "have different XYZ dimensions.",
                                    cimg_instance,
                                    p_warp._width,p_warp._height,p_warp._depth,p_warp._spectrum,p_warp._data);

      CImg<T> res(p_warp._width,p_warp._height,p_warp._depth,_spectrum);

      if (p_warp._spectrum==1) { // 1D warping
        if (mode>=3) { // Forward-relative warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atX(*(ptrs++),x + (float)*(ptrs0++),y,z,c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int X = x + (int)cimg::round(*(ptrs0++));
                if (X>=0 && X<width()) res(X,y,z,c) = *(ptrs++);
              }
            }
        } else if (mode==2) { // Forward-absolute warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atX(*(ptrs++),(float)*(ptrs0++),y,z,c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int X = (int)cimg::round(*(ptrs0++));
                if (X>=0 && X<width()) res(X,y,z,c) = *(ptrs++);
              }
            }
        } else if (mode==1) { // Backward-relative warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float mx = cimg::mod(x - (float)*(ptrs0++),w2);
                  *(ptrd++) = _cubic_atX_c(mx<width()?mx:w2 - mx - 1,y,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atX_pc(x - (float)*(ptrs0++),y,z,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atX_c(x - (float)*(ptrs0++),y,z,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = cubic_atX_c(x - (float)*(ptrs0++),y,z,c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float mx = cimg::mod(x - (float)*(ptrs0++),w2);
                  *(ptrd++) = (T)_linear_atX(mx<width()?mx:w2 - mx - 1,y,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atX_p(x - (float)*(ptrs0++),y,z,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atX(x - (float)*(ptrs0++),y,z,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)linear_atX(x - (float)*(ptrs0++),y,z,c,(T)0);
              }
            }
          else // Nearest-neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int mx = cimg::mod(x - (int)cimg::round(*(ptrs0++)),w2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,y,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod(x - (int)cimg::round(*(ptrs0++)),width()),y,z,c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atX(x - (int)cimg::round(*(ptrs0++)),y,z,c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atX(x - (int)cimg::round(*(ptrs0++)),y,z,c,(T)0);
              }
            }
        }
        else { // Backward-absolute warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float mx = cimg::mod((float)*(ptrs0++),w2);
                  *(ptrd++) = _cubic_atX_c(mx<width()?mx:w2 - mx - 1,0,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atX_pc((float)*(ptrs0++),0,0,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atX_c((float)*(ptrs0++),0,0,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = cubic_atX_c((float)*(ptrs0++),0,0,c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float mx = cimg::mod((float)*(ptrs0++),w2);
                  *(ptrd++) = (T)_linear_atX(mx<width()?mx:w2 - mx - 1,0,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atX_p((float)*(ptrs0++),0,0,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atX((float)*(ptrs0++),0,0,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)linear_atX((float)*(ptrs0++),0,0,c,(T)0);
              }
            }
          else // Nearest-neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int mx = cimg::mod((int)cimg::round(*(ptrs0++)),w2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,0,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod((int)cimg::round(*(ptrs0++)),width()),0,0,c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atX((int)cimg::round(*(ptrs0++)),0,0,c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atX((int)cimg::round(*(ptrs0++)),0,0,c,(T)0);
              }
            }
        }

      } else if (p_warp._spectrum==2) { // 2D warping
        if (mode>=3) { // Forward-relative warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atXY(*(ptrs++),x + (float)*(ptrs0++),y + (float)*(ptrs1++),z,c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int X = x + (int)cimg::round(*(ptrs0++)), Y = y + (int)cimg::round(*(ptrs1++));
                if (X>=0 && X<width() && Y>=0 && Y<height()) res(X,Y,z,c) = *(ptrs++);
              }
            }
        } else if (mode==2) { // Forward-absolute warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atXY(*(ptrs++),(float)*(ptrs0++),(float)*(ptrs1++),z,c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int X = (int)cimg::round(*(ptrs0++)), Y = (int)cimg::round(*(ptrs1++));
                if (X>=0 && X<width() && Y>=0 && Y<height()) res(X,Y,z,c) = *(ptrs++);
              }
            }
        } else if (mode==1) { // Backward-relative warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod(x - (float)*(ptrs0++),w2),
                    my = cimg::mod(y - (float)*(ptrs1++),h2);
                  *(ptrd++) = _cubic_atXY_c(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXY_pc(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXY_c(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = cubic_atXY_c(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod(x - (float)*(ptrs0++),w2),
                    my = cimg::mod(y - (float)*(ptrs1++),h2);
                  *(ptrd++) = (T)_linear_atXY(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXY_p(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXY(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)linear_atXY(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z,c,(T)0);
              }
            }
          else // Nearest-neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width(), h2 = 2*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int
                    mx = cimg::mod(x - (int)cimg::round(*(ptrs0++)),w2),
                    my = cimg::mod(y - (int)cimg::round(*(ptrs1++)),h2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,z,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod(x - (int)cimg::round(*(ptrs0++)),width()),
                                                     cimg::mod(y - (int)cimg::round(*(ptrs1++)),height()),z,c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atXY(x - (int)cimg::round(*(ptrs0++)),
                                                   y - (int)cimg::round(*(ptrs1++)),z,c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atXY(x - (int)cimg::round(*(ptrs0++)),
                                                  y - (int)cimg::round(*(ptrs1++)),z,c,(T)0);
              }
            }
        } else { // Backward-absolute warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod((float)*(ptrs0++),w2),
                    my = cimg::mod((float)*(ptrs1++),h2);
                  *(ptrd++) = _cubic_atXY_c(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXY_pc((float)*(ptrs0++),(float)*(ptrs1++),0,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXY_c((float)*(ptrs0++),(float)*(ptrs1++),0,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = cubic_atXY_c((float)*(ptrs0++),(float)*(ptrs1++),0,c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod((float)*(ptrs0++),w2),
                    my = cimg::mod((float)*(ptrs1++),h2);
                  *(ptrd++) = (T)_linear_atXY(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXY_p((float)*(ptrs0++),(float)*(ptrs1++),0,c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXY((float)*(ptrs0++),(float)*(ptrs1++),0,c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)linear_atXY((float)*(ptrs0++),(float)*(ptrs1++),0,c,(T)0);
              }
            }
          else // Nearest-neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width(), h2 = 2*height();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int
                    mx = cimg::mod((int)cimg::round(*(ptrs0++)),w2),
                    my = cimg::mod((int)cimg::round(*(ptrs1++)),h2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,my<height()?my:h2 - my - 1,0,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod((int)cimg::round(*(ptrs0++)),width()),
                                                     cimg::mod((int)cimg::round(*(ptrs1++)),height()),0,c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atXY((int)cimg::round(*(ptrs0++)),
                                                   (int)cimg::round(*(ptrs1++)),0,c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1); T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atXY((int)cimg::round(*(ptrs0++)),
                                                  (int)cimg::round(*(ptrs1++)),0,c,(T)0);
              }
            }
        }

      } else { // 3D warping
        if (mode>=3) { // Forward-relative warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
              const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atXYZ(*(ptrs++),x + (float)*(ptrs0++),y + (float)*(ptrs1++),
                                                    z + (float)*(ptrs2++),c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
              const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int
                  X = x + (int)cimg::round(*(ptrs0++)),
                  Y = y + (int)cimg::round(*(ptrs1++)),
                  Z = z + (int)cimg::round(*(ptrs2++));
                if (X>=0 && X<width() && Y>=0 && Y<height() && Z>=0 && Z<depth()) res(X,Y,Z,c) = *(ptrs++);
              }
            }
        } else if (mode==2) { // Forward-absolute warp
          res.fill((T)0);
          if (interpolation>=1) // Linear interpolation
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
              const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) res.set_linear_atXYZ(*(ptrs++),(float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),c);
            }
          else // Nearest-neighbor interpolation
            cimg_forYZC(res,y,z,c) {
              const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
              const T *ptrs = data(0,y,z,c);
              cimg_forX(res,x) {
                const int
                  X = (int)cimg::round(*(ptrs0++)),
                  Y = (int)cimg::round(*(ptrs1++)),
                  Z = (int)cimg::round(*(ptrs2++));
                if (X>=0 && X<width() && Y>=0 && Y<height() && Z>=0 && Z<depth()) res(X,Y,Z,c) = *(ptrs++);
              }
            }
        } else if (mode==1) { // Backward-relative warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height(), d2 = 2.f*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod(x - (float)*(ptrs0++),w2),
                    my = cimg::mod(y - (float)*(ptrs1++),h2),
                    mz = cimg::mod(z - (float)*(ptrs2++),d2);
                  *(ptrd++) = _cubic_atXYZ_c(mx<width()?mx:w2 - mx - 1,
                                             my<height()?my:h2 - my - 1,
                                             mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x)
                  *(ptrd++) = _cubic_atXYZ_pc(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z - (float)*(ptrs2++),c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x)
                  *(ptrd++) = _cubic_atXYZ_c(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z - (float)*(ptrs2++),c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x)
                  *(ptrd++) = cubic_atXYZ_c(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z - (float)*(ptrs2++),c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height(), d2 = 2.f*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod(x - (float)*(ptrs0++),w2),
                    my = cimg::mod(y - (float)*(ptrs1++),h2),
                    mz = cimg::mod(z - (float)*(ptrs2++),d2);
                  *(ptrd++) = (T)_linear_atXYZ(mx<width()?mx:w2 - mx - 1,
                                               my<height()?my:h2 - my - 1,
                                               mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXYZ_p(x - (float)*(ptrs0++),y - (float)*(ptrs1++),
                                                                z - (float)*(ptrs2++),c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x)
                  *(ptrd++) = (T)_linear_atXYZ(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z - (float)*(ptrs2++),c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x)
                  *(ptrd++) = (T)linear_atXYZ(x - (float)*(ptrs0++),y - (float)*(ptrs1++),z - (float)*(ptrs2++),c,(T)0);
              }
            }
          else // Nearest neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width(), h2 = 2*height(), d2 = 2*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int
                    mx = cimg::mod(x - (int)cimg::round(*(ptrs0++)),w2),
                    my = cimg::mod(y - (int)cimg::round(*(ptrs1++)),h2),
                    mz = cimg::mod(z - (int)cimg::round(*(ptrs2++)),d2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,
                                      my<height()?my:h2 - my - 1,
                                      mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod(x - (int)cimg::round(*(ptrs0++)),width()),
                                                     cimg::mod(y - (int)cimg::round(*(ptrs1++)),height()),
                                                     cimg::mod(z - (int)cimg::round(*(ptrs2++)),depth()),c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atXYZ(x - (int)cimg::round(*(ptrs0++)),
                                                    y - (int)cimg::round(*(ptrs1++)),
                                                    z - (int)cimg::round(*(ptrs2++)),c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atXYZ(x - (int)cimg::round(*(ptrs0++)),
                                                   y - (int)cimg::round(*(ptrs1++)),
                                                   z - (int)cimg::round(*(ptrs2++)),c,(T)0);
              }
            }
        } else { // Backward-absolute warp
          if (interpolation==2) // Cubic interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height(), d2 = 2.f*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod((float)*(ptrs0++),w2),
                    my = cimg::mod((float)*(ptrs1++),h2),
                    mz = cimg::mod((float)*(ptrs2++),d2);
                  *(ptrd++) = _cubic_atXYZ_c(mx<width()?mx:w2 - mx - 1,
                                             my<height()?my:h2 - my - 1,
                                             mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXYZ_pc((float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _cubic_atXYZ_c((float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = cubic_atXYZ_c((float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),
                                                           c,(T)0);
              }
            }
          else if (interpolation==1) // Linear interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const float w2 = 2.f*width(), h2 = 2.f*height(), d2 = 2.f*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const float
                    mx = cimg::mod((float)*(ptrs0++),w2),
                    my = cimg::mod((float)*(ptrs1++),h2),
                    mz = cimg::mod((float)*(ptrs2++),d2);
                  *(ptrd++) = (T)_linear_atXYZ(mx<width()?mx:w2 - mx - 1,
                                               my<height()?my:h2 - my - 1,
                                               mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 :// Periodic
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXYZ_p((float)*(ptrs0++),(float)*(ptrs1++),
                                                                (float)*(ptrs2++),c);
              }
              break;
            case 1 : // Neumann
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)_linear_atXYZ((float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),c);
              }
              break;
            default : // Dirichlet
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),1048576))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (T)linear_atXYZ((float)*(ptrs0++),(float)*(ptrs1++),(float)*(ptrs2++),
                                                             c,(T)0);
              }
            }
          else // Nearest-neighbor interpolation
            switch (boundary_conditions) {
            case 3 : { // Mirror
              const int w2 = 2*width(), h2 = 2*height(), d2 = 2*depth();
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(res.size(),4096))
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) {
                  const int
                    mx = cimg::mod((int)cimg::round(*(ptrs0++)),w2),
                    my = cimg::mod((int)cimg::round(*(ptrs1++)),h2),
                    mz = cimg::mod((int)cimg::round(*(ptrs2++)),d2);
                  *(ptrd++) = (*this)(mx<width()?mx:w2 - mx - 1,
                                      my<height()?my:h2 - my - 1,
                                      mz<depth()?mz:d2 - mz - 1,c);
                }
              }
            } break;
            case 2 : // Periodic
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = (*this)(cimg::mod((int)cimg::round(*(ptrs0++)),width()),
                                                     cimg::mod((int)cimg::round(*(ptrs1++)),height()),
                                                     cimg::mod((int)cimg::round(*(ptrs2++)),depth()),c);
              }
              break;
            case 1 : // Neumann
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = _atXYZ((int)cimg::round(*(ptrs0++)),
                                                    (int)cimg::round(*(ptrs1++)),
                                                    (int)cimg::round(*(ptrs2++)),c);
              }
              break;
            default : // Dirichlet
              cimg_forYZC(res,y,z,c) {
                const t *ptrs0 = p_warp.data(0,y,z,0), *ptrs1 = p_warp.data(0,y,z,1), *ptrs2 = p_warp.data(0,y,z,2);
                T *ptrd = res.data(0,y,z,c);
                cimg_forX(res,x) *(ptrd++) = atXYZ((int)cimg::round(*(ptrs0++)),
                                                   (int)cimg::round(*(ptrs1++)),
                                                   (int)cimg::round(*(ptrs2++)),c,(T)0);
              }
            }
        }
      }
      return res;
    }

    //! Generate a 2D representation of a 3D image, with XY, XZ and YZ views.
    /**
       \param x0 X-coordinate of the projection point.
       \param y0 Y-coordinate of the projection point.
       \param z0 Z-coordinate of the projection point.
    **/
    CImg<T> get_projections2d(const unsigned int x0, const unsigned int y0, const unsigned int z0) const {
      if (is_empty() || _depth<2) return +*this;
      const unsigned int
        _x0 = (x0>=_width)?_width - 1:x0,
        _y0 = (y0>=_height)?_height - 1:y0,
        _z0 = (z0>=_depth)?_depth - 1:z0;
      const CImg<T>
        img_xy = get_crop(0,0,_z0,0,_width - 1,_height - 1,_z0,_spectrum - 1),
        img_zy = get_crop(_x0,0,0,0,_x0,_height - 1,_depth - 1,_spectrum - 1).permute_axes("xzyc").
        resize(_depth,_height,1,-100,-1),
        img_xz = get_crop(0,_y0,0,0,_width - 1,_y0,_depth - 1,_spectrum - 1).resize(_width,_depth,1,-100,-1);
      return CImg<T>(_width + _depth,_height + _depth,1,_spectrum,cimg::min(img_xy.min(),img_zy.min(),img_xz.min())).
        draw_image(0,0,img_xy).draw_image(img_xy._width,0,img_zy).
        draw_image(0,img_xy._height,img_xz);
    }

    //! Construct a 2D representation of a 3D image, with XY,XZ and YZ views \inplace.
    CImg<T>& projections2d(const unsigned int x0, const unsigned int y0, const unsigned int z0) {
      if (_depth<2) return *this;
      return get_projections2d(x0,y0,z0).move_to(*this);
    }

    //! Crop image region.
    /**
       \param x0 = X-coordinate of the upper-left crop rectangle corner.
       \param y0 = Y-coordinate of the upper-left crop rectangle corner.
       \param z0 = Z-coordinate of the upper-left crop rectangle corner.
       \param c0 = C-coordinate of the upper-left crop rectangle corner.
       \param x1 = X-coordinate of the lower-right crop rectangle corner.
       \param y1 = Y-coordinate of the lower-right crop rectangle corner.
       \param z1 = Z-coordinate of the lower-right crop rectangle corner.
       \param c1 = C-coordinate of the lower-right crop rectangle corner.
       \param boundary_conditions = Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
    **/
    CImg<T>& crop(const int x0, const int y0, const int z0, const int c0,
                  const int x1, const int y1, const int z1, const int c1,
                  const unsigned int boundary_conditions=0) {
      return get_crop(x0,y0,z0,c0,x1,y1,z1,c1,boundary_conditions).move_to(*this);
    }

    //! Crop image region \newinstance.
    CImg<T> get_crop(const int x0, const int y0, const int z0, const int c0,
                     const int x1, const int y1, const int z1, const int c1,
                     const unsigned int boundary_conditions=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "crop(): Empty instance.",
                                    cimg_instance);
      const int
        nx0 = x0<x1?x0:x1, nx1 = x0^x1^nx0,
        ny0 = y0<y1?y0:y1, ny1 = y0^y1^ny0,
        nz0 = z0<z1?z0:z1, nz1 = z0^z1^nz0,
        nc0 = c0<c1?c0:c1, nc1 = c0^c1^nc0;
      const unsigned int
        _boundary_conditions = nx0>=0 && nx1<width() &&
                               ny0>=0 && ny1<height() &&
                               nz0>=0 && nz1<depth() &&
                               nc0>=0 && nc1<spectrum()?0:boundary_conditions;
      CImg<T> res(1U + nx1 - nx0,1U + ny1 - ny0,1U + nz1 - nz0,1U + nc1 - nc0);
      if (nx0<0 || nx1>=width() || ny0<0 || ny1>=height() || nz0<0 || nz1>=depth() || nc0<0 || nc1>=spectrum())
        switch (_boundary_conditions) {
        case 3 : { // Mirror
          const int w2 = 2*width(), h2 = 2*height(), d2 = 2*depth(), s2 = 2*spectrum();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*16 &&
                                                                     _height*_depth*_spectrum>=4))
          cimg_forXYZC(res,x,y,z,c) {
            const int
              mx = cimg::mod(nx0 + x,w2),
              my = cimg::mod(ny0 + y,h2),
              mz = cimg::mod(nz0 + z,d2),
              mc = cimg::mod(nc0 + c,s2);
            res(x,y,z,c) = (*this)(mx<width()?mx:w2 - mx - 1,
                                   my<height()?my:h2 - my - 1,
                                   mz<depth()?mz:d2 - mz - 1,
                                   mc<spectrum()?mc:s2 - mc - 1);
          }
        } break;
        case 2 : { // Periodic
          const int
            Nxp = (-nx0 + width() - 1)/width(), Nxn = (res.width() + nx0 + width() - 1)/width(),
            Nyp = (-ny0 + height() - 1)/height(), Nyn = (res.height() + ny0 + height() - 1)/height(),
            Nzp = (-nz0 + depth() - 1)/depth(), Nzn = (res.depth() + nz0 + depth() - 1)/depth(),
            Ncp = (-nc0 + spectrum() - 1)/spectrum(), Ncn = (res.spectrum() + nc0 + spectrum() - 1)/spectrum(),
            Nx = Nxp + Nxn, Ny = Nyp + Nyn, Nz = Nzp + Nzn, Nc = Ncp + Ncn,
            X0 = -nx0 - Nxp*width(), Y0 = -ny0 - Nyp*height(), Z0 = -nz0 - Nzp*depth(), C0 = -nc0 - Ncp*spectrum();
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                             cimg_openmp_if(Nx*Ny*Nz*Nc>=(cimg_openmp_sizefactor)*16))
          for (int c = 0; c<Nc; ++c)
            for (int z = 0; z<Nz; ++z)
              for (int y = 0; y<Ny; ++y) {
                const int C = C0 + c*spectrum(), Z = Z0 + z*depth(), Y = Y0 + y*height();
                for (int x = 0; x<Nx; ++x) {
                  const int X = X0 + x*width();
                  res.draw_image(X,Y,Z,C,*this);
                }
              }
        } break;
        case 1 : // Neumann
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*16 &&
                                                                     _height*_depth*_spectrum>=4))
          cimg_forXYZC(res,x,y,z,c) res(x,y,z,c) = _atXYZC(nx0 + x,ny0 + y,nz0 + z,nc0 + c);
          break;
        default : // Dirichlet
          res.fill((T)0).draw_image(-nx0,-ny0,-nz0,-nc0,*this);
        }
      else res.draw_image(-nx0,-ny0,-nz0,-nc0,*this);
      return res;
    }

    //! Crop image region \overload.
    CImg<T>& crop(const int x0, const int y0, const int z0,
                  const int x1, const int y1, const int z1,
                  const unsigned int boundary_conditions=0) {
      return crop(x0,y0,z0,0,x1,y1,z1,_spectrum - 1,boundary_conditions);
    }

    //! Crop image region \newinstance.
    CImg<T> get_crop(const int x0, const int y0, const int z0,
                     const int x1, const int y1, const int z1,
                     const unsigned int boundary_conditions=0) const {
      return get_crop(x0,y0,z0,0,x1,y1,z1,_spectrum - 1,boundary_conditions);
    }

    //! Crop image region \overload.
    CImg<T>& crop(const int x0, const int y0,
                  const int x1, const int y1,
                  const unsigned int boundary_conditions=0) {
      return crop(x0,y0,0,0,x1,y1,_depth - 1,_spectrum - 1,boundary_conditions);
    }

    //! Crop image region \newinstance.
    CImg<T> get_crop(const int x0, const int y0,
                     const int x1, const int y1,
                     const unsigned int boundary_conditions=0) const {
      return get_crop(x0,y0,0,0,x1,y1,_depth - 1,_spectrum - 1,boundary_conditions);
    }

    //! Crop image region \overload.
    CImg<T>& crop(const int x0, const int x1, const unsigned int boundary_conditions=0) {
      return crop(x0,0,0,0,x1,_height - 1,_depth - 1,_spectrum - 1,boundary_conditions);
    }

    //! Crop image region \newinstance.
    CImg<T> get_crop(const int x0, const int x1, const unsigned int boundary_conditions=0) const {
      return get_crop(x0,0,0,0,x1,_height - 1,_depth - 1,_spectrum - 1,boundary_conditions);
    }

    //! Autocrop image region, regarding the specified background value.
    CImg<T>& autocrop(const T& value, const char *const axes="czyx") {
      if (is_empty()) return *this;
      for (const char *s = axes; *s; ++s) {
        const char axis = cimg::lowercase(*s);
        const CImg<intT> coords = _autocrop(value,axis);
        if (coords[0]==-1 && coords[1]==-1) return assign(); // Image has only 'value' pixels
        else switch (axis) {
        case 'x' : {
          const int x0 = coords[0], x1 = coords[1];
          if (x0>=0 && x1>=0) crop(x0,x1);
        } break;
        case 'y' : {
          const int y0 = coords[0], y1 = coords[1];
          if (y0>=0 && y1>=0) crop(0,y0,_width - 1,y1);
        } break;
        case 'z' : {
          const int z0 = coords[0], z1 = coords[1];
          if (z0>=0 && z1>=0) crop(0,0,z0,_width - 1,_height - 1,z1);
        } break;
        default : {
          const int c0 = coords[0], c1 = coords[1];
          if (c0>=0 && c1>=0) crop(0,0,0,c0,_width - 1,_height - 1,_depth - 1,c1);
        }
        }
      }
      return *this;
    }

    //! Autocrop image region, regarding the specified background value \newinstance.
    CImg<T> get_autocrop(const T& value, const char *const axes="czyx") const {
      return (+*this).autocrop(value,axes);
    }

    //! Autocrop image region, regarding the specified background color.
    /**
       \param color Color used for the crop. If \c 0, color is guessed.
       \param axes Axes used for the crop.
    **/
    CImg<T>& autocrop(const T *const color=0, const char *const axes="zyx") {
      if (is_empty()) return *this;
      if (!color) { // Guess color
        const CImg<T> col1 = get_vector_at(0,0,0);
        const unsigned int w = _width, h = _height, d = _depth, s = _spectrum;
        autocrop(col1,axes);
        if (_width==w && _height==h && _depth==d && _spectrum==s) {
          const CImg<T> col2 = get_vector_at(w - 1,h - 1,d - 1);
          autocrop(col2,axes);
        }
        return *this;
      }
      for (const char *s = axes; *s; ++s) {
        const char axis = cimg::lowercase(*s);
        switch (axis) {
        case 'x' : {
          int x0 = width(), x1 = -1;
          cimg_forC(*this,c) {
            const CImg<intT> coords = get_shared_channel(c)._autocrop(color[c],'x');
            const int nx0 = coords[0], nx1 = coords[1];
            if (nx0>=0 && nx1>=0) { x0 = std::min(x0,nx0); x1 = std::max(x1,nx1); }
          }
          if (x0==width() && x1==-1) return assign(); else crop(x0,x1);
        } break;
        case 'y' : {
          int y0 = height(), y1 = -1;
          cimg_forC(*this,c) {
            const CImg<intT> coords = get_shared_channel(c)._autocrop(color[c],'y');
            const int ny0 = coords[0], ny1 = coords[1];
            if (ny0>=0 && ny1>=0) { y0 = std::min(y0,ny0); y1 = std::max(y1,ny1); }
          }
          if (y0==height() && y1==-1) return assign(); else crop(0,y0,_width - 1,y1);
        } break;
        default : {
          int z0 = depth(), z1 = -1;
          cimg_forC(*this,c) {
            const CImg<intT> coords = get_shared_channel(c)._autocrop(color[c],'z');
            const int nz0 = coords[0], nz1 = coords[1];
            if (nz0>=0 && nz1>=0) { z0 = std::min(z0,nz0); z1 = std::max(z1,nz1); }
          }
          if (z0==depth() && z1==-1) return assign(); else crop(0,0,z0,_width - 1,_height - 1,z1);
        }
        }
      }
      return *this;
    }

    //! Autocrop image region, regarding the specified background color \newinstance.
    CImg<T> get_autocrop(const T *const color=0, const char *const axes="zyx") const {
      return (+*this).autocrop(color,axes);
    }

    CImg<intT> _autocrop(const T& value, const char axis) const {
      CImg<intT> res;
      switch (cimg::lowercase(axis)) {
      case 'x' : {
        int x0 = -1, x1 = -1;
        cimg_forX(*this,x) cimg_forYZC(*this,y,z,c)
          if ((*this)(x,y,z,c)!=value) { x0 = x; x = width(); y = height(); z = depth(); c = spectrum(); }
        if (x0>=0) {
          for (int x = width() - 1; x>=0; --x) cimg_forYZC(*this,y,z,c)
            if ((*this)(x,y,z,c)!=value) { x1 = x; x = 0; y = height(); z = depth(); c = spectrum(); }
        }
        res = CImg<intT>::vector(x0,x1);
      } break;
      case 'y' : {
        int y0 = -1, y1 = -1;
        cimg_forY(*this,y) cimg_forXZC(*this,x,z,c)
          if ((*this)(x,y,z,c)!=value) { y0 = y; x = width(); y = height(); z = depth(); c = spectrum(); }
        if (y0>=0) {
          for (int y = height() - 1; y>=0; --y) cimg_forXZC(*this,x,z,c)
            if ((*this)(x,y,z,c)!=value) { y1 = y; x = width(); y = 0; z = depth(); c = spectrum(); }
        }
        res = CImg<intT>::vector(y0,y1);
      } break;
      case 'z' : {
        int z0 = -1, z1 = -1;
        cimg_forZ(*this,z) cimg_forXYC(*this,x,y,c)
          if ((*this)(x,y,z,c)!=value) { z0 = z; x = width(); y = height(); z = depth(); c = spectrum(); }
        if (z0>=0) {
          for (int z = depth() - 1; z>=0; --z) cimg_forXYC(*this,x,y,c)
            if ((*this)(x,y,z,c)!=value) { z1 = z; x = width(); y = height(); z = 0; c = spectrum(); }
        }
        res = CImg<intT>::vector(z0,z1);
      } break;
      default : {
        int c0 = -1, c1 = -1;
        cimg_forC(*this,c) cimg_forXYZ(*this,x,y,z)
          if ((*this)(x,y,z,c)!=value) { c0 = c; x = width(); y = height(); z = depth(); c = spectrum(); }
        if (c0>=0) {
          for (int c = spectrum() - 1; c>=0; --c) cimg_forXYZ(*this,x,y,z)
            if ((*this)(x,y,z,c)!=value) { c1 = c; x = width(); y = height(); z = depth(); c = 0; }
        }
        res = CImg<intT>::vector(c0,c1);
      }
      }
      return res;
    }

    //! Return specified image column.
    /**
       \param x0 Image column.
    **/
    CImg<T> get_column(const int x0) const {
      return get_columns(x0,x0);
    }

    //! Return specified image column \inplace.
    CImg<T>& column(const int x0) {
      return columns(x0,x0);
    }

    //! Return specified range of image columns.
    /**
       \param x0 Starting image column.
       \param x1 Ending image column.
    **/
    CImg<T>& columns(const int x0, const int x1) {
      return get_columns(x0,x1).move_to(*this);
    }

    //! Return specified range of image columns \inplace.
    CImg<T> get_columns(const int x0, const int x1) const {
      return get_crop(x0,0,0,0,x1,height() - 1,depth() - 1,spectrum() - 1);
    }

    //! Return specified image row.
    CImg<T> get_row(const int y0) const {
      return get_rows(y0,y0);
    }

    //! Return specified image row \inplace.
    /**
       \param y0 Image row.
    **/
    CImg<T>& row(const int y0) {
      return rows(y0,y0);
    }

    //! Return specified range of image rows.
    /**
       \param y0 Starting image row.
       \param y1 Ending image row.
    **/
    CImg<T> get_rows(const int y0, const int y1) const {
      return get_crop(0,y0,0,0,width() - 1,y1,depth() - 1,spectrum() - 1);
    }

    //! Return specified range of image rows \inplace.
    CImg<T>& rows(const int y0, const int y1) {
      return get_rows(y0,y1).move_to(*this);
    }

    //! Return specified image slice.
    /**
       \param z0 Image slice.
    **/
    CImg<T> get_slice(const int z0) const {
      return get_slices(z0,z0);
    }

    //! Return specified image slice \inplace.
    CImg<T>& slice(const int z0) {
      return slices(z0,z0);
    }

    //! Return specified range of image slices.
    /**
       \param z0 Starting image slice.
       \param z1 Ending image slice.
    **/
    CImg<T> get_slices(const int z0, const int z1) const {
      return get_crop(0,0,z0,0,width() - 1,height() - 1,z1,spectrum() - 1);
    }

    //! Return specified range of image slices \inplace.
    CImg<T>& slices(const int z0, const int z1) {
      return get_slices(z0,z1).move_to(*this);
    }

    //! Return specified image channel.
    /**
       \param c0 Image channel.
    **/
    CImg<T> get_channel(const int c0) const {
      return get_channels(c0,c0);
    }

    //! Return specified image channel \inplace.
    CImg<T>& channel(const int c0) {
      return channels(c0,c0);
    }

    //! Return specified range of image channels.
    /**
       \param c0 Starting image channel.
       \param c1 Ending image channel.
    **/
    CImg<T> get_channels(const int c0, const int c1) const {
      return get_crop(0,0,0,c0,width() - 1,height() - 1,depth() - 1,c1);
    }

    //! Return specified range of image channels \inplace.
    CImg<T>& channels(const int c0, const int c1) {
      return get_channels(c0,c1).move_to(*this);
    }

    //! Return stream line of a 2D or 3D vector field.
    CImg<floatT> get_streamline(const float x, const float y, const float z,
                                const float L=256, const float dl=0.1f,
                                const unsigned int interpolation_type=2, const bool is_backward_tracking=false,
                                const bool is_oriented_only=false) const {
      if (_spectrum!=2 && _spectrum!=3)
        throw CImgInstanceException(_cimg_instance
                                    "streamline(): Instance is not a 2D or 3D vector field.",
                                    cimg_instance);
      if (_spectrum==2) {
        if (is_oriented_only) {
          typename CImg<T>::_functor4d_streamline2d_oriented func(*this);
          return streamline(func,x,y,z,L,dl,interpolation_type,is_backward_tracking,true,
                            0,0,0,_width - 1.f,_height - 1.f,0.f);
        } else {
          typename CImg<T>::_functor4d_streamline2d_directed func(*this);
          return streamline(func,x,y,z,L,dl,interpolation_type,is_backward_tracking,false,
                            0,0,0,_width - 1.f,_height - 1.f,0.f);
        }
      }
      if (is_oriented_only) {
        typename CImg<T>::_functor4d_streamline3d_oriented func(*this);
        return streamline(func,x,y,z,L,dl,interpolation_type,is_backward_tracking,true,
                          0,0,0,_width - 1.f,_height - 1.f,_depth - 1.f);
      }
      typename CImg<T>::_functor4d_streamline3d_directed func(*this);
      return streamline(func,x,y,z,L,dl,interpolation_type,is_backward_tracking,false,
                        0,0,0,_width - 1.f,_height - 1.f,_depth - 1.f);
    }

    //! Return stream line of a 3D vector field.
    /**
       \param func Vector field function.
       \param x X-coordinate of the starting point of the streamline.
       \param y Y-coordinate of the starting point of the streamline.
       \param z Z-coordinate of the starting point of the streamline.
       \param L Streamline length.
       \param dl Streamline length increment.
       \param interpolation_type Type of interpolation.
         Can be <tt>{ 0=nearest integer | 1=linear | 2=2nd-order RK | 3=4th-order RK }</tt>.
       \param is_backward_tracking Indicates whether the streamline is estimated forward or backward.
       \param is_oriented_only Indicates whether the direction of the vectors must be ignored.
       \param x0 X-coordinate of the first bounding-box vertex.
       \param y0 Y-coordinate of the first bounding-box vertex.
       \param z0 Z-coordinate of the first bounding-box vertex.
       \param x1 X-coordinate of the second bounding-box vertex.
       \param y1 Y-coordinate of the second bounding-box vertex.
       \param z1 Z-coordinate of the second bounding-box vertex.
    **/
    template<typename tfunc>
    static CImg<floatT> streamline(const tfunc& func,
                                   const float x, const float y, const float z,
                                   const float L=256, const float dl=0.1f,
                                   const unsigned int interpolation_type=2, const bool is_backward_tracking=false,
                                   const bool is_oriented_only=false,
                                   const float x0=0, const float y0=0, const float z0=0,
                                   const float x1=0, const float y1=0, const float z1=0) {
      if (dl<=0)
        throw CImgArgumentException("CImg<%s>::streamline(): Invalid specified integration length %g "
                                    "(should be >0).",
                                    pixel_type(),
                                    dl);

      const bool is_bounded = (x0!=x1 || y0!=y1 || z0!=z1);
      if (L<=0 || (is_bounded && (x<x0 || x>x1 || y<y0 || y>y1 || z<z0 || z>z1))) return CImg<floatT>();
      const unsigned int size_L = (unsigned int)cimg::round(L/dl + 1);
      CImg<floatT> coordinates(size_L,3);
      const float dl2 = dl/2;
      float
        *ptr_x = coordinates.data(0,0),
        *ptr_y = coordinates.data(0,1),
        *ptr_z = coordinates.data(0,2),
        pu = (float)(dl*func(x,y,z,0)),
        pv = (float)(dl*func(x,y,z,1)),
        pw = (float)(dl*func(x,y,z,2)),
        X = x, Y = y, Z = z;

      switch (interpolation_type) {
      case 0 : { // Nearest integer interpolation
        cimg_forX(coordinates,l) {
          *(ptr_x++) = X; *(ptr_y++) = Y; *(ptr_z++) = Z;
          const int
            xi = (int)(X>0?X + 0.5f:X - 0.5f),
            yi = (int)(Y>0?Y + 0.5f:Y - 0.5f),
            zi = (int)(Z>0?Z + 0.5f:Z - 0.5f);
          float
            u = (float)(dl*func((float)xi,(float)yi,(float)zi,0)),
            v = (float)(dl*func((float)xi,(float)yi,(float)zi,1)),
            w = (float)(dl*func((float)xi,(float)yi,(float)zi,2));
          if (is_oriented_only && u*pu + v*pv + w*pw<0) { u = -u; v = -v; w = -w; }
          if (is_backward_tracking) { X-=(pu=u); Y-=(pv=v); Z-=(pw=w); } else { X+=(pu=u); Y+=(pv=v); Z+=(pw=w); }
          if (is_bounded && (X<x0 || X>x1 || Y<y0 || Y>y1 || Z<z0 || Z>z1)) break;
        }
      } break;
      case 1 : { // First-order interpolation
        cimg_forX(coordinates,l) {
          *(ptr_x++) = X; *(ptr_y++) = Y; *(ptr_z++) = Z;
          float
            u = (float)(dl*func(X,Y,Z,0)),
            v = (float)(dl*func(X,Y,Z,1)),
            w = (float)(dl*func(X,Y,Z,2));
          if (is_oriented_only && u*pu + v*pv + w*pw<0) { u = -u; v = -v; w = -w; }
          if (is_backward_tracking) { X-=(pu=u); Y-=(pv=v); Z-=(pw=w); } else { X+=(pu=u); Y+=(pv=v); Z+=(pw=w); }
          if (is_bounded && (X<x0 || X>x1 || Y<y0 || Y>y1 || Z<z0 || Z>z1)) break;
        }
      } break;
      case 2 : { // Second order interpolation
        cimg_forX(coordinates,l) {
          *(ptr_x++) = X; *(ptr_y++) = Y; *(ptr_z++) = Z;
          float
            u0 = (float)(dl2*func(X,Y,Z,0)),
            v0 = (float)(dl2*func(X,Y,Z,1)),
            w0 = (float)(dl2*func(X,Y,Z,2));
          if (is_oriented_only && u0*pu + v0*pv + w0*pw<0) { u0 = -u0; v0 = -v0; w0 = -w0; }
          float
            u = (float)(dl*func(X + u0,Y + v0,Z + w0,0)),
            v = (float)(dl*func(X + u0,Y + v0,Z + w0,1)),
            w = (float)(dl*func(X + u0,Y + v0,Z + w0,2));
          if (is_oriented_only && u*pu + v*pv + w*pw<0) { u = -u; v = -v; w = -w; }
          if (is_backward_tracking) { X-=(pu=u); Y-=(pv=v); Z-=(pw=w); } else { X+=(pu=u); Y+=(pv=v); Z+=(pw=w); }
          if (is_bounded && (X<x0 || X>x1 || Y<y0 || Y>y1 || Z<z0 || Z>z1)) break;
        }
      } break;
      default : { // Fourth order interpolation
        cimg_forX(coordinates,k) {
          *(ptr_x++) = X; *(ptr_y++) = Y; *(ptr_z++) = Z;
          float
            u0 = (float)(dl2*func(X,Y,Z,0)),
            v0 = (float)(dl2*func(X,Y,Z,1)),
            w0 = (float)(dl2*func(X,Y,Z,2));
          if (is_oriented_only && u0*pu + v0*pv + w0*pw<0) { u0 = -u0; v0 = -v0; w0 = -w0; }
          float
            u1 = (float)(dl2*func(X + u0,Y + v0,Z + w0,0)),
            v1 = (float)(dl2*func(X + u0,Y + v0,Z + w0,1)),
            w1 = (float)(dl2*func(X + u0,Y + v0,Z + w0,2));
          if (is_oriented_only && u1*pu + v1*pv + w1*pw<0) { u1 = -u1; v1 = -v1; w1 = -w1; }
          float
            u2 = (float)(dl2*func(X + u1,Y + v1,Z + w1,0)),
            v2 = (float)(dl2*func(X + u1,Y + v1,Z + w1,1)),
            w2 = (float)(dl2*func(X + u1,Y + v1,Z + w1,2));
          if (is_oriented_only && u2*pu + v2*pv + w2*pw<0) { u2 = -u2; v2 = -v2; w2 = -w2; }
          float
            u3 = (float)(dl2*func(X + u2,Y + v2,Z + w2,0)),
            v3 = (float)(dl2*func(X + u2,Y + v2,Z + w2,1)),
            w3 = (float)(dl2*func(X + u2,Y + v2,Z + w2,2));
          if (is_oriented_only && u3*pu + v3*pv + w3*pw<0) { u3 = -u3; v3 = -v3; w3 = -w3; }
          const float
            u = (u0 + u3)/3 + (u1 + u2)/1.5f,
            v = (v0 + v3)/3 + (v1 + v2)/1.5f,
            w = (w0 + w3)/3 + (w1 + w2)/1.5f;
          if (is_backward_tracking) { X-=(pu=u); Y-=(pv=v); Z-=(pw=w); } else { X+=(pu=u); Y+=(pv=v); Z+=(pw=w); }
          if (is_bounded && (X<x0 || X>x1 || Y<y0 || Y>y1 || Z<z0 || Z>z1)) break;
        }
      }
      }
      if (ptr_x!=coordinates.data(0,1)) coordinates.resize((int)(ptr_x-coordinates.data()),3,1,1,0);
      return coordinates;
    }

    //! Return stream line of a 3D vector field \overload.
    static CImg<floatT> streamline(const char *const expression,
                                   const float x, const float y, const float z,
                                   const float L=256, const float dl=0.1f,
                                   const unsigned int interpolation_type=2, const bool is_backward_tracking=true,
                                   const bool is_oriented_only=false,
                                   const float x0=0, const float y0=0, const float z0=0,
                                   const float x1=0, const float y1=0, const float z1=0) {
      _functor4d_streamline_expr func(expression);
      return streamline(func,x,y,z,L,dl,interpolation_type,is_backward_tracking,is_oriented_only,x0,y0,z0,x1,y1,z1);
    }

    struct _functor4d_streamline2d_directed {
      const CImg<T>& ref;
      _functor4d_streamline2d_directed(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
        return c<2?(float)ref._linear_atXY(x,y,(int)z,c):0;
      }
    };

    struct _functor4d_streamline3d_directed {
      const CImg<T>& ref;
      _functor4d_streamline3d_directed(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
        return (float)ref._linear_atXYZ(x,y,z,c);
      }
    };

    struct _functor4d_streamline2d_oriented {
      const CImg<T>& ref;
      mutable CImg<floatT> I;
      _functor4d_streamline2d_oriented(const CImg<T>& pref):ref(pref),I(2,2,1,2) {}
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
#define _cimg_vecalign2d(i,j) \
        if (I(i,j,0)*I(0,0,0) + I(i,j,1)*I(0,0,1)<0) { I(i,j,0) = -I(i,j,0); I(i,j,1) = -I(i,j,1); }
        int
          xi = (int)x - (x>=0?0:1), nxi = xi + 1,
          yi = (int)y - (y>=0?0:1), nyi = yi + 1,
          zi = (int)z;
        const float
          dx = x - xi,
          dy = y - yi;
        if (c==0) {
          if (xi<0) xi = 0;
          if (nxi<0) nxi = 0;
          if (xi>=ref.width()) xi = ref.width() - 1;
          if (nxi>=ref.width()) nxi = ref.width() - 1;
          if (yi<0) yi = 0;
          if (nyi<0) nyi = 0;
          if (yi>=ref.height()) yi = ref.height() - 1;
          if (nyi>=ref.height()) nyi = ref.height() - 1;
          I(0,0,0) = (float)ref(xi,yi,zi,0);   I(0,0,1) = (float)ref(xi,yi,zi,1);
          I(1,0,0) = (float)ref(nxi,yi,zi,0);  I(1,0,1) = (float)ref(nxi,yi,zi,1);
          I(1,1,0) = (float)ref(nxi,nyi,zi,0); I(1,1,1) = (float)ref(nxi,nyi,zi,1);
          I(0,1,0) = (float)ref(xi,nyi,zi,0);  I(0,1,1) = (float)ref(xi,nyi,zi,1);
          _cimg_vecalign2d(1,0); _cimg_vecalign2d(1,1); _cimg_vecalign2d(0,1);
        }
        return c<2?(float)I._linear_atXY(dx,dy,0,c):0;
      }
    };

    struct _functor4d_streamline3d_oriented {
      const CImg<T>& ref;
      mutable CImg<floatT> I;
      _functor4d_streamline3d_oriented(const CImg<T>& pref):ref(pref),I(2,2,2,3) {}
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
#define _cimg_vecalign3d(i,j,k) if (I(i,j,k,0)*I(0,0,0,0) + I(i,j,k,1)*I(0,0,0,1) + I(i,j,k,2)*I(0,0,0,2)<0) { \
  I(i,j,k,0) = -I(i,j,k,0); I(i,j,k,1) = -I(i,j,k,1); I(i,j,k,2) = -I(i,j,k,2); }
        int
          xi = (int)x - (x>=0?0:1), nxi = xi + 1,
          yi = (int)y - (y>=0?0:1), nyi = yi + 1,
          zi = (int)z - (z>=0?0:1), nzi = zi + 1;
        const float
          dx = x - xi,
          dy = y - yi,
          dz = z - zi;
        if (c==0) {
          if (xi<0) xi = 0;
          if (nxi<0) nxi = 0;
          if (xi>=ref.width()) xi = ref.width() - 1;
          if (nxi>=ref.width()) nxi = ref.width() - 1;
          if (yi<0) yi = 0;
          if (nyi<0) nyi = 0;
          if (yi>=ref.height()) yi = ref.height() - 1;
          if (nyi>=ref.height()) nyi = ref.height() - 1;
          if (zi<0) zi = 0;
          if (nzi<0) nzi = 0;
          if (zi>=ref.depth()) zi = ref.depth() - 1;
          if (nzi>=ref.depth()) nzi = ref.depth() - 1;
          I(0,0,0,0) = (float)ref(xi,yi,zi,0); I(0,0,0,1) = (float)ref(xi,yi,zi,1);
          I(0,0,0,2) = (float)ref(xi,yi,zi,2); I(1,0,0,0) = (float)ref(nxi,yi,zi,0);
          I(1,0,0,1) = (float)ref(nxi,yi,zi,1); I(1,0,0,2) = (float)ref(nxi,yi,zi,2);
          I(1,1,0,0) = (float)ref(nxi,nyi,zi,0); I(1,1,0,1) = (float)ref(nxi,nyi,zi,1);
          I(1,1,0,2) = (float)ref(nxi,nyi,zi,2); I(0,1,0,0) = (float)ref(xi,nyi,zi,0);
          I(0,1,0,1) = (float)ref(xi,nyi,zi,1); I(0,1,0,2) = (float)ref(xi,nyi,zi,2);
          I(0,0,1,0) = (float)ref(xi,yi,nzi,0); I(0,0,1,1) = (float)ref(xi,yi,nzi,1);
          I(0,0,1,2) = (float)ref(xi,yi,nzi,2); I(1,0,1,0) = (float)ref(nxi,yi,nzi,0);
          I(1,0,1,1) = (float)ref(nxi,yi,nzi,1);  I(1,0,1,2) = (float)ref(nxi,yi,nzi,2);
          I(1,1,1,0) = (float)ref(nxi,nyi,nzi,0); I(1,1,1,1) = (float)ref(nxi,nyi,nzi,1);
          I(1,1,1,2) = (float)ref(nxi,nyi,nzi,2); I(0,1,1,0) = (float)ref(xi,nyi,nzi,0);
          I(0,1,1,1) = (float)ref(xi,nyi,nzi,1);  I(0,1,1,2) = (float)ref(xi,nyi,nzi,2);
          _cimg_vecalign3d(1,0,0); _cimg_vecalign3d(1,1,0); _cimg_vecalign3d(0,1,0);
          _cimg_vecalign3d(0,0,1); _cimg_vecalign3d(1,0,1); _cimg_vecalign3d(1,1,1); _cimg_vecalign3d(0,1,1);
        }
        return (float)I._linear_atXYZ(dx,dy,dz,c);
      }
    };

    struct _functor4d_streamline_expr {
      _cimg_math_parser *mp;
      ~_functor4d_streamline_expr() { mp->end(); delete mp; }
      _functor4d_streamline_expr(const char *const expr):mp(0) {
        mp = new _cimg_math_parser(expr,"streamline",CImg<T>::const_empty(),0);
      }
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
        return (float)(*mp)(x,y,z,c);
      }
    };

    //! Return a shared-memory image referencing a range of pixels of the image instance.
    /**
       \param x0 X-coordinate of the starting pixel.
       \param x1 X-coordinate of the ending pixel.
       \param y0 Y-coordinate.
       \param z0 Z-coordinate.
       \param c0 C-coordinate.
     **/
    CImg<T> get_shared_points(const unsigned int x0, const unsigned int x1,
                              const unsigned int y0=0, const unsigned int z0=0, const unsigned int c0=0) {
      const ulongT
        beg = (ulongT)offset(x0,y0,z0,c0),
        end = (ulongT)offset(x1,y0,z0,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_points(): Invalid request for "
                                    "a shared-memory subset (%u->%u,%u,%u,%u).",
                                    cimg_instance,
                                    x0,x1,y0,z0,c0);
      return CImg<T>(_data + beg,x1 - x0 + 1,1,1,1,true);
    }

    //! Return a shared-memory image referencing a range of pixels of the image instance \const.
    const CImg<T> get_shared_points(const unsigned int x0, const unsigned int x1,
                                    const unsigned int y0=0, const unsigned int z0=0, const unsigned int c0=0) const {
      const ulongT
        beg = (ulongT)offset(x0,y0,z0,c0),
        end = (ulongT)offset(x1,y0,z0,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_points(): Invalid request for "
                                    "a shared-memory subset (%u->%u,%u,%u,%u).",
                                    cimg_instance,
                                    x0,x1,y0,z0,c0);
      return CImg<T>(_data + beg,x1 - x0 + 1,1,1,1,true);
    }

    //! Return a shared-memory image referencing a range of rows of the image instance.
    /**
       \param y0 Y-coordinate of the starting row.
       \param y1 Y-coordinate of the ending row.
       \param z0 Z-coordinate.
       \param c0 C-coordinate.
    **/
    CImg<T> get_shared_rows(const unsigned int y0, const unsigned int y1,
                             const unsigned int z0=0, const unsigned int c0=0) {
      const ulongT
        beg = (ulongT)offset(0,y0,z0,c0),
        end = (ulongT)offset(0,y1,z0,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_rows(): Invalid request for "
                                    "a shared-memory subset (0->%u,%u->%u,%u,%u).",
                                    cimg_instance,
                                    _width - 1,y0,y1,z0,c0);
      return CImg<T>(_data + beg,_width,y1 - y0 + 1,1,1,true);
    }

    //! Return a shared-memory image referencing a range of rows of the image instance \const.
    const CImg<T> get_shared_rows(const unsigned int y0, const unsigned int y1,
                                   const unsigned int z0=0, const unsigned int c0=0) const {
      const ulongT
        beg = (ulongT)offset(0,y0,z0,c0),
        end = (ulongT)offset(0,y1,z0,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_rows(): Invalid request for "
                                    "a shared-memory subset (0->%u,%u->%u,%u,%u).",
                                    cimg_instance,
                                    _width - 1,y0,y1,z0,c0);
      return CImg<T>(_data + beg,_width,y1 - y0 + 1,1,1,true);
    }

    //! Return a shared-memory image referencing one row of the image instance.
    /**
       \param y0 Y-coordinate.
       \param z0 Z-coordinate.
       \param c0 C-coordinate.
    **/
    CImg<T> get_shared_row(const unsigned int y0, const unsigned int z0=0, const unsigned int c0=0) {
      return get_shared_rows(y0,y0,z0,c0);
    }

    //! Return a shared-memory image referencing one row of the image instance \const.
    const CImg<T> get_shared_row(const unsigned int y0, const unsigned int z0=0, const unsigned int c0=0) const {
      return get_shared_rows(y0,y0,z0,c0);
    }

    //! Return a shared memory image referencing a range of slices of the image instance.
    /**
       \param z0 Z-coordinate of the starting slice.
       \param z1 Z-coordinate of the ending slice.
       \param c0 C-coordinate.
    **/
    CImg<T> get_shared_slices(const unsigned int z0, const unsigned int z1, const unsigned int c0=0) {
      const ulongT
        beg = (ulongT)offset(0,0,z0,c0),
        end = (ulongT)offset(0,0,z1,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_slices(): Invalid request for "
                                    "a shared-memory subset (0->%u,0->%u,%u->%u,%u).",
                                    cimg_instance,
                                    _width - 1,_height - 1,z0,z1,c0);
      return CImg<T>(_data + beg,_width,_height,z1 - z0 + 1,1,true);
    }

    //! Return a shared memory image referencing a range of slices of the image instance \const.
    const CImg<T> get_shared_slices(const unsigned int z0, const unsigned int z1, const unsigned int c0=0) const {
      const ulongT
        beg = (ulongT)offset(0,0,z0,c0),
        end = (ulongT)offset(0,0,z1,c0);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_slices(): Invalid request for "
                                    "a shared-memory subset (0->%u,0->%u,%u->%u,%u).",
                                    cimg_instance,
                                    _width - 1,_height - 1,z0,z1,c0);
      return CImg<T>(_data + beg,_width,_height,z1 - z0 + 1,1,true);
    }

    //! Return a shared-memory image referencing one slice of the image instance.
    /**
       \param z0 Z-coordinate.
       \param c0 C-coordinate.
    **/
    CImg<T> get_shared_slice(const unsigned int z0, const unsigned int c0=0) {
      return get_shared_slices(z0,z0,c0);
    }

    //! Return a shared-memory image referencing one slice of the image instance \const.
    const CImg<T> get_shared_slice(const unsigned int z0, const unsigned int c0=0) const {
      return get_shared_slices(z0,z0,c0);
    }

    //! Return a shared-memory image referencing a range of channels of the image instance.
    /**
       \param c0 C-coordinate of the starting channel.
       \param c1 C-coordinate of the ending channel.
    **/
    CImg<T> get_shared_channels(const unsigned int c0, const unsigned int c1) {
      const ulongT
        beg = (ulongT)offset(0,0,0,c0),
        end = (ulongT)offset(0,0,0,c1);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_channels(): Invalid request for "
                                    "a shared-memory subset (0->%u,0->%u,0->%u,%u->%u).",
                                    cimg_instance,
                                    _width - 1,_height - 1,_depth - 1,c0,c1);
      return CImg<T>(_data + beg,_width,_height,_depth,c1 - c0 + 1,true);
    }

    //! Return a shared-memory image referencing a range of channels of the image instance \const.
    const CImg<T> get_shared_channels(const unsigned int c0, const unsigned int c1) const {
      const ulongT
        beg = (ulongT)offset(0,0,0,c0),
        end = (ulongT)offset(0,0,0,c1);
      if (beg>end || beg>=size() || end>=size())
        throw CImgArgumentException(_cimg_instance
                                    "get_shared_channels(): Invalid request for "
                                    "a shared-memory subset (0->%u,0->%u,0->%u,%u->%u).",
                                    cimg_instance,
                                    _width - 1,_height - 1,_depth - 1,c0,c1);
      return CImg<T>(_data + beg,_width,_height,_depth,c1 - c0 + 1,true);
    }

    //! Return a shared-memory image referencing one channel of the image instance.
    /**
       \param c0 C-coordinate.
    **/
    CImg<T> get_shared_channel(const unsigned int c0) {
      return get_shared_channels(c0,c0);
    }

    //! Return a shared-memory image referencing one channel of the image instance \const.
    const CImg<T> get_shared_channel(const unsigned int c0) const {
      return get_shared_channels(c0,c0);
    }

    //! Return a shared-memory version of the image instance.
    CImg<T> get_shared() {
      return CImg<T>(_data,_width,_height,_depth,_spectrum,true);
    }

    //! Return a shared-memory version of the image instance \const.
    const CImg<T> get_shared() const {
      return CImg<T>(_data,_width,_height,_depth,_spectrum,true);
    }

    //! Split the image into a list along specified axis.
    /**
       \param axis Splitting axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param nb Number of split parts.
       \param max_parts Number of max parts allowed for the split.
       \note
       - If \c nb==0, the instance image is split into blocks of equal values along the specified axis.
       - If \c nb>0, the instance image is split into \c nb blocks.
       - If \c nb<0, the instance image is split into blocks of -\c nb pixels wide.
    **/
    CImgList<T> get_split(const char axis, const int nb=-1, const unsigned int max_parts=~0U) const {
      CImgList<T> res;
      if (is_empty() || !max_parts) return res;
      if (max_parts==1) return res.assign(*this);
      const char _axis = cimg::lowercase(axis);
      const unsigned int mp1 = max_parts - 1;

      if (nb<0) { // Split by block size
        const unsigned int dp = (unsigned int)-nb;
        switch (_axis) {
        case 'x': {
          if (max_parts==1 || dp>=_width) res.assign(*this);
          else {
            res.assign(std::min(max_parts,_width/dp + (_width%dp?1:0)));
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*128 &&
                                                           _height*_depth*_spectrum>=128))
            cimglist_for(res,p)
              if (p!=res.width() - 1) get_columns(p*dp,(p + 1)*dp - 1).move_to(res[p]);
              else get_columns(p*dp,_width - 1).move_to(res[p]);
          }
        } break;
        case 'y': {
          if (max_parts==1 || dp>=_height) res.assign(*this);
          else {
            res.assign(std::min(max_parts,_height/dp + (_height%dp?1:0)));
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*128 &&
                                                           _width*_depth*_spectrum>=128))
            cimglist_for(res,p)
              if (p!=res.width() - 1) get_rows(p*dp,(p + 1)*dp - 1).move_to(res[p]);
              else get_rows(p*dp,_height - 1).move_to(res[p]);
          }
        } break;
        case 'z': {
          if (max_parts==1 || dp>=_depth) res.assign(*this);
          else {
            res.assign(std::min(max_parts,_depth/dp + (_depth%dp?1:0)));
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*128 &&
                                                           _width*_height*_spectrum>=128))
            cimglist_for(res,p)
              if (p!=res.width() - 1) get_slices(p*dp,(p + 1)*dp - 1).move_to(res[p]);
              else get_slices(p*dp,_depth - 1).move_to(res[p]);
          }
        } break;
        case 'c' : {
          if (max_parts==1 || dp>=_spectrum) res.assign(*this);
          else {
            res.assign(std::min(max_parts,_spectrum/dp + (_spectrum%dp?1:0)));
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*128 &&
                                                           _width*_height*_depth>=128))
            cimglist_for(res,p)
              if (p!=res.width() - 1) get_channels(p*dp,(p + 1)*dp - 1).move_to(res[p]);
              else get_channels(p*dp,_spectrum - 1).move_to(res[p]);
          }
        }
        }
      } else if (nb>0) { // Split by number of (non-homogeneous) blocks
        const unsigned int siz = _axis=='x'?_width:_axis=='y'?_height:_axis=='z'?_depth:_axis=='c'?_spectrum:0;
        if ((unsigned int)nb>siz)
          throw CImgArgumentException(_cimg_instance
                                      "get_split(): Instance cannot be split along %c-axis into %u blocks.",
                                      cimg_instance,
                                      axis,nb);
        if (nb==1) res.assign(*this);
        else {
          int err = (int)siz;
          unsigned int _p = 0;
          switch (_axis) {
          case 'x' :
            cimg_forX(*this,p) if ((err-=nb)<=0) {
              get_columns(_p,p).move_to(res);
              if (res._width>=mp1) { get_columns(p,_width - 1).move_to(res); break; }
              err+=(int)siz; _p = p + 1U;
            }
            break;
          case 'y' :
            cimg_forY(*this,p) if ((err-=nb)<=0) {
              get_rows(_p,p).move_to(res);
              if (res._width>=mp1) { get_rows(p,_height - 1).move_to(res); break; }
              err+=(int)siz; _p = p + 1U;
            }
            break;
          case 'z' :
            cimg_forZ(*this,p) if ((err-=nb)<=0) {
              get_slices(_p,p).move_to(res);
              if (res._width>=mp1) { get_slices(p,_depth - 1).move_to(res); break; }
              err+=(int)siz; _p = p + 1U;
            }
            break;
          case 'c' :
            cimg_forC(*this,p) if ((err-=nb)<=0) {
              get_channels(_p,p).move_to(res);
              if (res._width>=mp1) { get_channels(p,_spectrum - 1).move_to(res); break; }
              err+=(int)siz; _p = p + 1U;
            }
          }
        }
      } else { // Split by equal values according to specified axis
        T current = *_data;
        switch (_axis) {
        case 'x' : {
          int i0 = 0;
          cimg_forX(*this,i)
            if ((*this)(i)!=current) {
              get_columns(i0,i - 1).move_to(res);
              if (res._width>=mp1) break;
              i0 = i; current = (*this)(i);
            }
          get_columns(i0,width() - 1).move_to(res);
        } break;
        case 'y' : {
          int i0 = 0;
          cimg_forY(*this,i)
            if ((*this)(0,i)!=current) {
              get_rows(i0,i - 1).move_to(res);
              if (res._width>=mp1) break;
              i0 = i; current = (*this)(0,i);
            }
          get_rows(i0,height() - 1).move_to(res);
        } break;
        case 'z' : {
          int i0 = 0;
          cimg_forZ(*this,i)
            if ((*this)(0,0,i)!=current) {
              get_slices(i0,i - 1).move_to(res);
              if (res._width>=mp1) break;
              i0 = i; current = (*this)(0,0,i);
            }
          get_slices(i0,depth() - 1).move_to(res);
        } break;
        case 'c' : {
          int i0 = 0;
          cimg_forC(*this,i)
            if ((*this)(0,0,0,i)!=current) {
              get_channels(i0,i - 1).move_to(res);
              if (res._width>=mp1) break;
              i0 = i; current = (*this)(0,0,0,i);
            }
          get_channels(i0,spectrum() - 1).move_to(res);
        } break;
        default : {
          longT i0 = 0;
          cimg_foroff(*this,i)
            if ((*this)[i]!=current) {
              CImg<T>(_data + i0,1,(unsigned int)(i - i0)).move_to(res);
              if (res._width>=mp1) break;
              i0 = (longT)i; current = (*this)[i];
            }
          CImg<T>(_data + i0,1,(unsigned int)(size() - i0)).move_to(res);
        }
        }
      }
      return res;
    }

    //! Split the image into a list of sub-images according to a specified sequence of splitting values
    //! and optionally an axis.
    /**
       \param values Splitting value sequence.
       \param axis Axis along which the splitting is performed. Can be '0' to ignore axis.
       \param keep_values Indicates whether the splitting sequence must be kept in the split blocks.
     **/
    template<typename t>
    CImgList<T> get_split(const CImg<t>& values, const char axis=0, const bool keep_values=true) const {
      typedef _cimg_Tt Tt;

      CImgList<T> res;
      if (is_empty()) return res;
      const ulongT vsiz = values.size();
      const char _axis = cimg::lowercase(axis);
      if (!vsiz) return CImgList<T>(*this);
      if (vsiz==1) { // Split according to a single value
        const T value = (T)*values;
        switch (_axis) {
        case 'x' : {
          unsigned int i0 = 0, i = 0;
          do {
            while (i<_width && (*this)(i)==value) ++i;
            if (i>i0) { if (keep_values) get_columns(i0,i - 1).move_to(res); i0 = i; }
            while (i<_width && (*this)(i)!=value) ++i;
            if (i>i0) { get_columns(i0,i - 1).move_to(res); i0 = i; }
          } while (i<_width);
        } break;
        case 'y' : {
          unsigned int i0 = 0, i = 0;
          do {
            while (i<_height && (*this)(0,i)==value) ++i;
            if (i>i0) { if (keep_values) get_rows(i0,i - 1).move_to(res); i0 = i; }
            while (i<_height && (*this)(0,i)!=value) ++i;
            if (i>i0) { get_rows(i0,i - 1).move_to(res); i0 = i; }
          } while (i<_height);
        } break;
        case 'z' : {
          unsigned int i0 = 0, i = 0;
          do {
            while (i<_depth && (*this)(0,0,i)==value) ++i;
            if (i>i0) { if (keep_values) get_slices(i0,i - 1).move_to(res); i0 = i; }
            while (i<_depth && (*this)(0,0,i)!=value) ++i;
            if (i>i0) { get_slices(i0,i - 1).move_to(res); i0 = i; }
          } while (i<_depth);
        } break;
        case 'c' : {
          unsigned int i0 = 0, i = 0;
          do {
            while (i<_spectrum && (*this)(0,0,0,i)==value) ++i;
            if (i>i0) { if (keep_values) get_channels(i0,i - 1).move_to(res); i0 = i; }
            while (i<_spectrum && (*this)(0,0,0,i)!=value) ++i;
            if (i>i0) { get_channels(i0,i - 1).move_to(res); i0 = i; }
          } while (i<_spectrum);
        } break;
        default : {
          const ulongT siz = size();
          ulongT i0 = 0, i = 0;
          do {
            while (i<siz && (*this)[i]==value) ++i;
            if (i>i0) {
              if (keep_values) CImg<T>(_data + i0,1,(unsigned int)(i - i0)).move_to(res);
              i0 = i;
            }
            while (i<siz && (*this)[i]!=value) ++i;
            if (i>i0) { CImg<T>(_data + i0,1,(unsigned int)(i - i0)).move_to(res); i0 = i; }
          } while (i<siz);
        }
        }
      } else { // Split according to multiple values
        ulongT j = 0;
        switch (_axis) {
        case 'x' : {
          unsigned int i0 = 0, i1 = 0, i = 0;
          do {
            if ((Tt)(*this)(i)==(Tt)*values) {
              i1 = i; j = 0;
              while (i<_width && (Tt)(*this)(i)==(Tt)values[j]) { ++i; if (++j>=vsiz) j = 0; }
              i-=(unsigned int)j;
              if (i>i1) {
                if (i1>i0) get_columns(i0,i1 - 1).move_to(res);
                if (keep_values) get_columns(i1,i - 1).move_to(res);
                i0 = i;
              } else ++i;
            } else ++i;
          } while (i<_width);
          if (i0<_width) get_columns(i0,width() - 1).move_to(res);
        } break;
        case 'y' : {
          unsigned int i0 = 0, i1 = 0, i = 0;
          do {
            if ((Tt)(*this)(0,i)==(Tt)*values) {
              i1 = i; j = 0;
              while (i<_height && (Tt)(*this)(0,i)==(Tt)values[j]) { ++i; if (++j>=vsiz) j = 0; }
              i-=(unsigned int)j;
              if (i>i1) {
                if (i1>i0) get_rows(i0,i1 - 1).move_to(res);
                if (keep_values) get_rows(i1,i - 1).move_to(res);
                i0 = i;
              } else ++i;
            } else ++i;
          } while (i<_height);
          if (i0<_height) get_rows(i0,height() - 1).move_to(res);
        } break;
        case 'z' : {
          unsigned int i0 = 0, i1 = 0, i = 0;
          do {
            if ((Tt)(*this)(0,0,i)==(Tt)*values) {
              i1 = i; j = 0;
              while (i<_depth && (Tt)(*this)(0,0,i)==(Tt)values[j]) { ++i; if (++j>=vsiz) j = 0; }
              i-=(unsigned int)j;
              if (i>i1) {
                if (i1>i0) get_slices(i0,i1 - 1).move_to(res);
                if (keep_values) get_slices(i1,i - 1).move_to(res);
                i0 = i;
              } else ++i;
            } else ++i;
          } while (i<_depth);
          if (i0<_depth) get_slices(i0,depth() - 1).move_to(res);
        } break;
        case 'c' : {
          unsigned int i0 = 0, i1 = 0, i = 0;
          do {
            if ((Tt)(*this)(0,0,0,i)==(Tt)*values) {
              i1 = i; j = 0;
              while (i<_spectrum && (Tt)(*this)(0,0,0,i)==(Tt)values[j]) { ++i; if (++j>=vsiz) j = 0; }
              i-=(unsigned int)j;
              if (i>i1) {
                if (i1>i0) get_channels(i0,i1 - 1).move_to(res);
                if (keep_values) get_channels(i1,i - 1).move_to(res);
                i0 = i;
              } else ++i;
            } else ++i;
          } while (i<_spectrum);
          if (i0<_spectrum) get_channels(i0,spectrum() - 1).move_to(res);
        } break;
        default : {
          const ulongT siz = size();
          ulongT i0 = 0, i1 = 0, i = 0;
          do {
            if ((Tt)(*this)[i]==(Tt)*values) {
              i1 = i; j = 0;
              while (i<siz && (Tt)(*this)[i]==(Tt)values[j]) { ++i; if (++j>=vsiz) j = 0; }
              i-=(unsigned int)j;
              if (i>i1) {
                if (i1>i0) CImg<T>(_data + i0,1,(unsigned int)(i1 - i0)).move_to(res);
                if (keep_values) CImg<T>(_data + i1,1,(unsigned int)(i - i1)).move_to(res);
                i0 = i;
              } else ++i;
            } else ++i;
          } while (i<siz);
          if (i0<siz) CImg<T>(_data + i0,1,(unsigned int)(siz - i0)).move_to(res);
        } break;
        }
      }
      return res;
    }

    //! Append two images along specified axis.
    /**
       \param img Image to append with instance image.
       \param axis Concatenation axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param align Concatenation alignment in \c [0,1].
    **/
    template<typename t>
    CImg<T>& append(const CImg<t>& img, const char axis='x', const float align=0) {
      if (is_empty()) return assign(img,false);
      if (!img) return *this;
      return get_append(img,axis,align).move_to(*this);
    }

    //! Append two images along specified axis \const.
    template<typename t>
    CImg<_cimg_Tt> get_append(const CImg<t>& img, const char axis='x', const float align=0) const {
      if (is_empty()) return CImg<_cimg_Tt>(img,false);
      if (!img) return CImg<_cimg_Tt>(*this,false);
      CImg<_cimg_Tt> res;
      switch (cimg::lowercase(axis)) {
        case 'x' : {
          res.assign(_width + img._width,std::max(_height,img._height),
                     std::max(_depth,img._depth),std::max(_spectrum,img._spectrum),0);
          return res.draw_image(0,
                                (int)(align*(res._height - _height)),
                                (int)(align*(res._depth - _depth)),
                                (int)(align*(res._spectrum - _spectrum)),
                                *this).
            draw_image(_width,
                       (int)(align*(res._height - img._height)),
                       (int)(align*(res._depth - img._depth)),
                       (int)(align*(res._spectrum - img._spectrum)),
                       img);
        } break;
        case 'y' : {
          res.assign(std::max(_width,img._width),_height + img._height,
                     std::max(_depth,img._depth),std::max(_spectrum,img._spectrum),0);
          return res.draw_image((int)(align*(res._width - _width)),
                                0,
                                (int)(align*(res._depth - _depth)),
                                (int)(align*(res._spectrum - _spectrum)),
                                *this).
            draw_image((int)(align*(res._width - img._width)),
                       _height,
                       (int)(align*(res._depth - img._depth)),
                       (int)(align*(res._spectrum - img._spectrum)),
                       img);
        } break;
        case 'z' : {
          res.assign(std::max(_width,img._width),std::max(_height,img._height),
                     _depth + img._depth,std::max(_spectrum,img._spectrum),0);
          return res.draw_image((int)(align*(res._width - _width)),
                                (int)(align*(res._height - _height)),
                                0,
                                (int)(align*(res._spectrum - _spectrum)),
                                *this).
            draw_image((int)(align*(res._width - img._width)),
                       (int)(align*(res._height - img._height)),
                       _depth,
                       (int)(align*(res._spectrum - img._spectrum)),
                       img);
        } break;
        default : {
          res.assign(std::max(_width,img._width),std::max(_height,img._height),
                     std::max(_depth,img._depth),_spectrum + img._spectrum,0);
          return res.draw_image((int)(align*(res._width - _width)),
                                (int)(align*(res._height - _height)),
                                (int)(align*(res._depth - _depth)),
                                0,
                                *this).
            draw_image((int)(align*(res._width - img._width)),
                       (int)(align*(res._height - img._height)),
                       (int)(align*(res._depth - img._depth)),
                       _spectrum,
                       img);
        } break;
      }
      return res;
    }

    //@}
    //---------------------------------------
    //
    //! \name Filtering / Transforms
    //@{
    //---------------------------------------

    //! Correlate the image with a kernel.
    /**
       \param kernel = the correlation kernel.
       \param boundary_conditions Boundary condition. Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param is_normalized = enable local normalization.
       \param channel_mode Channel processing mode.
                           Can be { 0=all | 1=one for one (default) | 2=partial sum | 3=full sum }.
       \param xcenter X-coordinate of the kernel center (~0U>>1 means 'centered').
       \param ycenter Y-coordinate of the kernel center (~0U>>1 means 'centered').
       \param zcenter Z-coordinate of the kernel center (~0U>>1 means 'centered').
       \param xstride Stride along the X-axis.
       \param ystride Stride along the Y-axis.
       \param zstride Stride along the Z-axis.
       \param xdilation Dilation along the X-axis.
       \param ydilation Dilation along the Y-axis.
       \param zdilation Dilation along the Z-axis.
       \param xoffset X-offset.
       \param yoffset Y-offset.
       \param zoffset Z-offset.
       \param xsize Width of the resulting image (~0U means 'instance_width/xstride').
       \param ysize Height of the resulting image (~0U means 'instance_height/ystride').
       \param zsize Depth of the resulting image (~0U means 'instance_depth/zstride').
       \note
       - The correlation of the image instance \p *this by the kernel \p kernel is defined to be:
       \f$ res(x,y,z) = sum_{i,j,k} (*this)(\alpha_x\;x + \beta_x\;(i - c_x),\alpha_y\;y + \beta_y\;(j -
                    c_y),\alpha_z\;z + \beta_z\;(k - c_z))*kernel(i,j,k) \f$
    **/
    template<typename t>
    CImg<T>& correlate(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                       const bool is_normalized=false, const unsigned int channel_mode=1,
                       const int xcenter=(int)(~0U>>1),
                       const int ycenter=(int)(~0U>>1),
                       const int zcenter=(int)(~0U>>1),
                       const unsigned int xstride=1,
                       const unsigned int ystride=1,
                       const unsigned int zstride=1,
                       const int xdilation=1, const int ydilation=1, const int zdilation=1,
                       const int xoffset=0, const int yoffset=0, const int zoffset=0,
                       const unsigned int xsize=~0U,
                       const unsigned int ysize=~0U,
                       const unsigned int zsize=~0U) {
      if (is_empty() || !kernel) return *this;
      return get_correlate(kernel,boundary_conditions,is_normalized,channel_mode,
                           xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                           xoffset,yoffset,zoffset,xsize,ysize,zsize).move_to(*this);
    }

    template<typename t>
    CImg<_cimg_Ttfloat> get_correlate(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                                      const bool is_normalized=false, const unsigned int channel_mode=1,
                                      const int xcenter=(int)(~0U>>1),
                                      const int ycenter=(int)(~0U>>1),
                                      const int zcenter=(int)(~0U>>1),
                                      const unsigned int xstride=1,
                                      const unsigned int ystride=1,
                                      const unsigned int zstride=1,
                                      const int xdilation=1, const int ydilation=1, const int zdilation=1,
                                      const int xoffset=0, const int yoffset=0, const int zoffset=0,
                                      const unsigned int xsize=~0U,
                                      const unsigned int ysize=~0U,
                                      const unsigned int zsize=~0U) const {
      return _correlate(kernel,boundary_conditions,is_normalized,channel_mode,
                        xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                        xoffset,yoffset,zoffset,xsize,ysize,zsize,false);
    }

    //! Correlate the image with a kernel \newinstance.
    template<typename t>
    CImg<_cimg_Ttfloat> _correlate(const CImg<t>& kernel, const unsigned int boundary_conditions,
                                   const bool is_normalized, const unsigned int channel_mode,
                                   const int xcenter, const int ycenter, const int zcenter,
                                   const unsigned int xstride,
                                   const unsigned int ystride,
                                   const unsigned int zstride,
                                   const int xdilation, const int ydilation, const int zdilation,
                                   const int xoffset, const int yoffset, const int zoffset,
                                   const unsigned int xsize, const unsigned int ysize, const unsigned int zsize,
                                   const bool is_convolve) const {
      typedef _cimg_Ttfloat Ttfloat;
      CImg<Ttfloat> res;
      _cimg_abort_init_openmp;
      cimg_abort_init;
      if (is_empty() || !kernel) return *this;

      const unsigned int
        _xsize = xsize==~0U?_width/xstride:xsize,
        _ysize = ysize==~0U?_height/ystride:ysize,
        _zsize = zsize==~0U?_depth/zstride:zsize;
      const ulongT
        res_wh = (ulongT)_xsize*_ysize,
        res_whd = (ulongT)_xsize*_ysize*_zsize;
      if (!xsize || !ysize || !zsize) return CImg<Ttfloat>();

      int
        _xcenter = xcenter==(int)(~0U>>1)?kernel.width()/2 - 1 + (kernel.width()%2):xcenter,
        _ycenter = ycenter==(int)(~0U>>1)?kernel.height()/2 - 1 + (kernel.height()%2):ycenter,
        _zcenter = zcenter==(int)(~0U>>1)?kernel.depth()/2 - 1 + (kernel.depth()%2):zcenter,
        _xdilation = xdilation, _ydilation = ydilation, _zdilation = zdilation;

      CImg<t> _kernel;
      if (is_convolve) { // If convolution, go back to correlation
        if (kernel.size()/kernel.spectrum()<=27) {
          _kernel = CImg<t>(kernel._data,kernel.size()/kernel._spectrum,1,1,kernel._spectrum,true).
            get_mirror('x').resize(kernel,-1);
          _xcenter = kernel.width() - 1 - _xcenter;
          _ycenter = kernel.height() - 1 - _ycenter;
          _zcenter = kernel.depth() - 1 - _zcenter;
        } else { _kernel = kernel.get_shared(); _xdilation*=-1; _ydilation*=-1; _zdilation*=-1; }
      } else _kernel = kernel.get_shared();

      const int
        smin = std::min(spectrum(),_kernel.spectrum()),
        smax = std::max(spectrum(),_kernel.spectrum()),
        cend = !channel_mode?spectrum()*_kernel.spectrum():smax;

      res.assign(_xsize,_ysize,_zsize,
                 !channel_mode?_spectrum*_kernel._spectrum:
                 channel_mode==1?smax:
                 channel_mode==2?(int)std::ceil((float)smax/smin):1);
      const ulongT res_siz = res_whd*res._spectrum;
      if (channel_mode>=2) res.fill(0);

      const bool
#if cimg_use_openmp==1
        is_master_thread = !omp_get_thread_num(),
#else
        is_master_thread = true,
#endif
        is_outer_parallel = is_master_thread &&
        (res._spectrum>=cimg::nb_cpus() || (res_siz<=(cimg_openmp_sizefactor)*32768 && res._spectrum>1)),
        is_inner_parallel = is_master_thread &&
        (!is_outer_parallel && res_whd>=(cimg_openmp_sizefactor)*32768);
      cimg::unused(is_inner_parallel,is_outer_parallel);
      const int
        w = width(), h = height(), d = depth(),
        w1 = w  - 1, h1 = h - 1, d1 = d - 1,
        w2 = 2*w, h2 = 2*h, d2 = 2*d;
      const ulongT wh = (ulongT)w*h, whd = wh*d;

      // Reshape kernel to enable optimizations for a few cases.
      if (boundary_conditions==1 &&
          _kernel._width>1 && _kernel._height>1 &&
          ((_kernel._depth==1 && _kernel._width<=5 && _kernel._height<=5) ||
           (_kernel._depth<=3 && _kernel._width<=3 && _kernel._height<=3)) &&
          xstride==1 && ystride==1 && zstride==1 &&
          xoffset>=0 && yoffset>=0 && zoffset>=0 &&
          xoffset + _xsize<=_width && yoffset + _ysize<=_height && zoffset + _zsize<=_depth) {
        const unsigned int M = cimg::max(_kernel._width,_kernel._height,_kernel._depth);
        _kernel.assign(_kernel.get_resize(M + 1 - (M%2),M + 1 - (M%2),_kernel._depth>1?M + 1 - (M%2):1,-100,
                                          0,0,1,1,1),false);
        _xcenter = _ycenter = (int)M/2;
        if (_kernel._depth>1) _zcenter = (int)M/2;
      }

      // Optimized version for a few particular cases (3x3, 5x5 and 3x3x3 kernels, with a few other conditions).
      if (boundary_conditions==1 &&
          _kernel._width==_kernel._height &&
          ((_kernel._depth==1 && (_kernel._width==3 || _kernel._width==5)) ||
           (_kernel._depth==_kernel._width && _kernel._width==3)) &&
          _xcenter==_kernel.width()/2 && _ycenter==_kernel.height()/2 && _zcenter==_kernel.depth()/2 &&
          xstride==1 && ystride==1 && zstride==1 &&
          xoffset>=0 && yoffset>=0 && zoffset>=0 &&
          xoffset + _xsize<=_width && yoffset + _ysize<=_height && zoffset + _zsize<=_depth) {

        switch (_kernel._depth) {
        case 3 : { // 3x3x3 centered kernel
          cimg_pragma_openmp(parallel for cimg_openmp_if(is_outer_parallel))
          for (int c = 0; c<cend; ++c) _cimg_abort_try_openmp2 {
            cimg_abort_test2;
            const CImg<T> I = get_shared_channel(c%_spectrum);
            const CImg<t> K = _kernel.get_shared_channel(!channel_mode?c/_spectrum:c%_kernel._spectrum);
            CImg<Ttfloat> _resu = channel_mode<=1?res.get_shared_channel(c):
              CImg<Ttfloat>(res.width(),res.height(),res.depth(),1);
            if (is_normalized) {
              const Ttfloat M = (Ttfloat)K.magnitude(2), M2 = M*M;
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
              cimg_forXYZ(res,X,Y,Z) {
                const int
                  x = xoffset + X, y = yoffset + Y, z = zoffset + Z,
                  px = x - xdilation>0?x - xdilation:0, nx = x + xdilation<w1?x + xdilation:w1,
                  py = y - ydilation>0?y - ydilation:0, ny = y + ydilation<h1?y + ydilation:h1,
                  pz = z - zdilation>0?z - zdilation:0, nz = z + zdilation<d1?z + zdilation:d1;
                const Ttfloat N = M2*(cimg::sqr(I(px,py,pz)) + cimg::sqr(I(x,py,pz)) + cimg::sqr(I(nx,py,pz)) +
                                      cimg::sqr(I(px,y,pz)) + cimg::sqr(I(x,y,pz)) + cimg::sqr(I(nx,y,pz)) +
                                      cimg::sqr(I(px,ny,pz)) + cimg::sqr(I(x,ny,pz)) + cimg::sqr(I(nx,ny,pz)) +
                                      cimg::sqr(I(px,py,z)) + cimg::sqr(I(x,py,z)) + cimg::sqr(I(nx,py,z)) +
                                      cimg::sqr(I(px,y,z)) + cimg::sqr(I(x,y,z)) + cimg::sqr(I(nx,y,z)) +
                                      cimg::sqr(I(px,ny,z)) + cimg::sqr(I(x,ny,z)) + cimg::sqr(I(nx,ny,z)) +
                                      cimg::sqr(I(px,py,nz)) + cimg::sqr(I(x,py,nz)) + cimg::sqr(I(nx,py,nz)) +
                                      cimg::sqr(I(px,y,nz)) + cimg::sqr(I(x,y,nz)) + cimg::sqr(I(nx,y,nz)) +
                                      cimg::sqr(I(px,ny,nz)) + cimg::sqr(I(x,ny,nz)) + cimg::sqr(I(nx,ny,nz)));
                _resu(X,Y,Z) = (Ttfloat)(N?(K[0]*I(px,py,pz) + K[1]*I(x,py,pz) + K[2]*I(nx,py,pz) +
                                            K[3]*I(px,y,pz) + K[4]*I(x,y,pz) + K[5]*I(nx,y,pz) +
                                            K[6]*I(px,ny,pz) + K[7]*I(x,ny,pz) + K[8]*I(nx,ny,pz) +
                                            K[9]*I(px,py,z) + K[10]*I(x,py,z) + K[11]*I(nx,py,z) +
                                            K[12]*I(px,y,z) + K[13]*I(x,y,z) + K[14]*I(nx,y,z) +
                                            K[15]*I(px,ny,z) + K[16]*I(x,ny,z) + K[17]*I(nx,ny,z) +
                                            K[18]*I(px,py,nz) + K[19]*I(x,py,nz) + K[20]*I(nx,py,nz) +
                                            K[21]*I(px,y,nz) + K[22]*I(x,y,nz) + K[23]*I(nx,y,nz) +
                                            K[24]*I(px,ny,nz) + K[25]*I(x,ny,nz) + K[26]*I(nx,ny,nz))/std::sqrt(N):0);
              }
            } else {
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
              cimg_forXYZ(res,X,Y,Z) {
                const int
                  x = xoffset + X, y = yoffset + Y, z = zoffset + Z,
                  px = x - xdilation>0?x - xdilation:0, nx = x + xdilation<w1?x + xdilation:w1,
                  py = y - ydilation>0?y - ydilation:0, ny = y + ydilation<h1?y + ydilation:h1,
                  pz = z - zdilation>0?z - zdilation:0, nz = z + zdilation<d1?z + zdilation:d1;
                _resu(X,Y,Z) = (Ttfloat)(K[0]*I(px,py,pz) + K[1]*I(x,py,pz) + K[2]*I(nx,py,pz) +
                                         K[3]*I(px,y,pz) + K[4]*I(x,y,pz) + K[5]*I(nx,y,pz) +
                                         K[6]*I(px,ny,pz) + K[7]*I(x,ny,pz) + K[8]*I(nx,ny,pz) +
                                         K[9]*I(px,py,z) + K[10]*I(x,py,z) + K[11]*I(nx,py,z) +
                                         K[12]*I(px,y,z) + K[13]*I(x,y,z) + K[14]*I(nx,y,z) +
                                         K[15]*I(px,ny,z) + K[16]*I(x,ny,z) + K[17]*I(nx,ny,z) +
                                         K[18]*I(px,py,nz) + K[19]*I(x,py,nz) + K[20]*I(nx,py,nz) +
                                         K[21]*I(px,y,nz) + K[22]*I(x,y,nz) + K[23]*I(nx,y,nz) +
                                         K[24]*I(px,ny,nz) + K[25]*I(x,ny,nz) + K[26]*I(nx,ny,nz));
              }
            }
            if (channel_mode==2)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(c/smin)+=_resu;
            else if (channel_mode==3)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(0)+=_resu;
          } _cimg_abort_catch_openmp2
        } break;

        default :
        case 1 :
          switch (_kernel._width) {
          case 5 : { // 5x5 centered kernel
            cimg_pragma_openmp(parallel for cimg_openmp_if(is_outer_parallel))
            for (int c = 0; c<cend; ++c) _cimg_abort_try_openmp2 {
              cimg_abort_test2;
              const CImg<T> I = get_shared_channel(c%_spectrum);
              const CImg<t> K = _kernel.get_shared_channel(!channel_mode?c/_spectrum:c%_kernel._spectrum);
              CImg<Ttfloat> _resu = channel_mode<=1?res.get_shared_channel(c):
                CImg<Ttfloat>(res.width(),res.height(),res.depth(),1);
              if (is_normalized) {
                const Ttfloat M = (Ttfloat)K.magnitude(2), M2 = M*M;
                cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
                cimg_forXYZ(res,X,Y,z) {
                  const int
                    x = xoffset + X, y = yoffset + Y,
                    px = x - xdilation>0?x - xdilation:0, bx = px - xdilation>0?px - xdilation:0,
                    nx = x + xdilation<w1?x + xdilation:w1, ax = nx + xdilation<w1?nx + xdilation:w1,
                    py = y - ydilation>0?y - ydilation:0, by = py - ydilation>0?py - ydilation:0,
                    ny = y + ydilation<h1?y + ydilation:h1, ay = ny + ydilation<h1?ny + ydilation:h1;
                  const Ttfloat N = M2*(cimg::sqr(I(bx,by,z)) + cimg::sqr(I(px,by,z)) + cimg::sqr(I(x,by,z)) +
                                        cimg::sqr(I(nx,by,z)) + cimg::sqr(I(ax,by,z)) +
                                        cimg::sqr(I(bx,py,z)) + cimg::sqr(I(px,py,z)) + cimg::sqr(I(x,py,z)) +
                                        cimg::sqr(I(nx,py,z)) + cimg::sqr(I(ax,py,z)) +
                                        cimg::sqr(I(bx,y,z)) + cimg::sqr(I(px,y,z)) + cimg::sqr(I(x,y,z)) +
                                        cimg::sqr(I(nx,y,z)) + cimg::sqr(I(ax,y,z)) +
                                        cimg::sqr(I(bx,ny,z)) + cimg::sqr(I(px,ny,z)) + cimg::sqr(I(x,ny,z)) +
                                        cimg::sqr(I(nx,ny,z)) + cimg::sqr(I(ax,ny,z)) +
                                        cimg::sqr(I(bx,ay,z)) + cimg::sqr(I(px,ay,z)) + cimg::sqr(I(x,ay,z)) +
                                        cimg::sqr(I(nx,ay,z)) + cimg::sqr(I(ax,ay,z)));
                  _resu(X,Y,z) = (Ttfloat)(N?(K[0]*I(bx,by,z) + K[1]*I(px,by,z) + K[2]*I(x,by,z) +
                                              K[3]*I(nx,by,z) + K[4]*I(ax,by,z) +
                                              K[5]*I(bx,py,z) + K[6]*I(px,py,z) + K[7]*I(x,py,z) +
                                              K[8]*I(nx,py,z) + K[9]*I(ax,py,z) +
                                              K[10]*I(bx,y,z) + K[11]*I(px,y,z) + K[12]*I(x,y,z) +
                                              K[13]*I(nx,y,z) + K[14]*I(ax,y,z) +
                                              K[15]*I(bx,ny,z) + K[16]*I(px,ny,z) + K[17]*I(x,ny,z) +
                                              K[18]*I(nx,ny,z) + K[19]*I(ax,ny,z) +
                                              K[20]*I(bx,ay,z) + K[21]*I(px,ay,z) + K[22]*I(x,ay,z) +
                                              K[23]*I(nx,ay,z) + K[24]*I(ax,ay,z))/std::sqrt(N):0);
                }
              } else {
                cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
                cimg_forXYZ(res,X,Y,z) {
                  const int
                    x = xoffset + X, y = yoffset + Y,
                    px = x - xdilation>0?x - xdilation:0, bx = px - xdilation>0?px - xdilation:0,
                    nx = x + xdilation<w1?x + xdilation:w1, ax = nx + xdilation<w1?nx + xdilation:w1,
                    py = y - ydilation>0?y - ydilation:0, by = py - ydilation>0?py - ydilation:0,
                    ny = y + ydilation<h1?y + ydilation:h1, ay = ny + ydilation<h1?ny + ydilation:h1;
                  _resu(X,Y,z) = (Ttfloat)(K[0]*I(bx,by,z) + K[1]*I(px,by,z) + K[2]*I(x,by,z) +
                                           K[3]*I(nx,by,z) + K[4]*I(ax,by,z) +
                                           K[5]*I(bx,py,z) + K[6]*I(px,py,z) + K[7]*I(x,py,z) +
                                           K[8]*I(nx,py,z) + K[9]*I(ax,py,z) +
                                           K[10]*I(bx,y,z) + K[11]*I(px,y,z) + K[12]*I(x,y,z) +
                                           K[13]*I(nx,y,z) + K[14]*I(ax,y,z) +
                                           K[15]*I(bx,ny,z) + K[16]*I(px,ny,z) + K[17]*I(x,ny,z) +
                                           K[18]*I(nx,ny,z) + K[19]*I(ax,ny,z) +
                                           K[20]*I(bx,ay,z) + K[21]*I(px,ay,z) + K[22]*I(x,ay,z) +
                                           K[23]*I(nx,ay,z) + K[24]*I(ax,ay,z));
                }
              }
            if (channel_mode==2)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(c/smin)+=_resu;
            else if (channel_mode==3)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(0)+=_resu;
            } _cimg_abort_catch_openmp2
          } break;

          case 3 : { // 3x3 centered kernel
            cimg_pragma_openmp(parallel for cimg_openmp_if(is_outer_parallel))
            for (int c = 0; c<cend; ++c) _cimg_abort_try_openmp2 {
              cimg_abort_test2;
              const CImg<T> I = get_shared_channel(c%_spectrum);
              const CImg<t> K = _kernel.get_shared_channel(!channel_mode?c/_spectrum:c%_kernel._spectrum);
              CImg<Ttfloat> _resu = channel_mode<=1?res.get_shared_channel(c):
                CImg<Ttfloat>(res.width(),res.height(),res.depth(),1);
              if (is_normalized) {
                const Ttfloat M = (Ttfloat)K.magnitude(2), M2 = M*M;
                cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
                cimg_forXYZ(res,X,Y,z) {
                  const int
                    x = xoffset + X, y = yoffset + Y,
                    px = x - xdilation>0?x - xdilation:0, nx = x + xdilation<w1?x + xdilation:w1,
                    py = y - ydilation>0?y - ydilation:0, ny = y + ydilation<h1?y + ydilation:h1;
                  const Ttfloat N = M2*(cimg::sqr(I(px,py,z)) + cimg::sqr(I(x,py,z)) + cimg::sqr(I(nx,py,z)) +
                                        cimg::sqr(I(px,y,z)) + cimg::sqr(I(x,y,z)) + cimg::sqr(I(nx,y,z)) +
                                        cimg::sqr(I(px,ny,z)) + cimg::sqr(I(x,ny,z)) + cimg::sqr(I(nx,ny,z)));
                  _resu(X,Y,z) = (Ttfloat)(N?(K[0]*I(px,py,z) + K[1]*I(x,py,z) + K[2]*I(nx,py,z) +
                                              K[3]*I(px,y,z) + K[4]*I(x,y,z) + K[5]*I(nx,y,z) +
                                              K[6]*I(px,ny,z) + K[7]*I(x,ny,z) + K[8]*I(nx,ny,z))/std::sqrt(N):0);
                }
              } else {
                cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
                cimg_forXYZ(res,X,Y,z) {
                  const int
                    x = xoffset + X, y = yoffset + Y,
                    px = x - xdilation>0?x - xdilation:0, nx = x + xdilation<w1?x + xdilation:w1,
                    py = y - ydilation>0?y - ydilation:0, ny = y + ydilation<h1?y + ydilation:h1;
                  _resu(X,Y,z) = (Ttfloat)(K[0]*I(px,py,z) + K[1]*I(x,py,z) + K[2]*I(nx,py,z) +
                                           K[3]*I(px,y,z)  + K[4]*I(x,y,z)  + K[5]*I(nx,y,z) +
                                           K[6]*I(px,ny,z) + K[7]*I(x,ny,z) + K[8]*I(nx,ny,z));
                }
              }
            if (channel_mode==2)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(c/smin)+=_resu;
            else if (channel_mode==3)
              cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(0)+=_resu;
            } _cimg_abort_catch_openmp2
          } break;
          }
        }
      } else if (_kernel._width==1 && _kernel._height==1 && _kernel._depth==1 &&
                 !_xcenter && !_ycenter && !_zcenter &&
                 xstride==1 && ystride==1 && zstride==1 &&
                 xoffset>=0 && yoffset>=0 && zoffset>=0 &&
                 xoffset + _xsize<=_width && yoffset + _ysize<=_height && zoffset + _zsize<=_depth) {

        // Special optimization for 1x1 kernel.
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_outer_parallel))
        for (int c = 0; c<cend; ++c) {
          const t valK = _kernel[!channel_mode?c/_spectrum:c%_kernel._spectrum];
          CImg<T> I = get_crop(xoffset,yoffset,zoffset,c%_spectrum,
                               xoffset + _xsize - 1,yoffset + _ysize - 1,zoffset + _zsize - 1,c%_spectrum);
          if (valK!=1) I*=valK;
          if (is_normalized) I.sign();
          switch (channel_mode) {
          case 0 : // All
          case 1 : // One for one
            res.get_shared_channel(c) = I;
            break;
          case 2 : // Partial sum
            cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(c/smin)+=I;
            break;
          case 3 : // Full sum
            cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(0)+=I;
            break;
          }
        }
      } else { // Generic version
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_outer_parallel))
        for (int c = 0; c<cend; ++c) _cimg_abort_try_openmp2 {
          cimg_abort_test2;
          const CImg<T> I = get_shared_channel(c%_spectrum);
          const CImg<t> K = _kernel.get_shared_channel(!channel_mode?c/_spectrum:c%_kernel._spectrum);
          CImg<Ttfloat> _resu = channel_mode<=1?res.get_shared_channel(c):
            CImg<Ttfloat>(res.width(),res.height(),res.depth(),1);
          Ttfloat M = 0, M2 = 0;
          if (is_normalized) { M = (Ttfloat)K.magnitude(2); M2 = cimg::sqr(M); }

#define _cimg_correlate_x const int ix = xstride*x + xoffset + _xdilation*(p - _xcenter)
#define _cimg_correlate_y const int iy = ystride*y + yoffset + _ydilation*(q - _ycenter)
#define _cimg_correlate_z const int iz = zstride*z + zoffset + _zdilation*(r - _zcenter)

#define _cimg_correlate_x_dirichlet const bool is_in_x = ix>=0 && ix<w
#define _cimg_correlate_y_dirichlet const bool is_in_y = iy>=0 && iy<h
#define _cimg_correlate_z_dirichlet const bool is_in_z = iz>=0 && iz<d

#define _cimg_correlate_x_neumann const int nix = cimg::cut(ix,0,w1)
#define _cimg_correlate_y_neumann const int niy = cimg::cut(iy,0,h1)
#define _cimg_correlate_z_neumann const int niz = cimg::cut(iz,0,d1)

#define _cimg_correlate_x_periodic const int nix = cimg::mod(ix,w)
#define _cimg_correlate_y_periodic const int niy = cimg::mod(iy,h)
#define _cimg_correlate_z_periodic const int niz = cimg::mod(iz,d)

#define _cimg_correlate_x_mirror const int mx = cimg::mod(ix,w2), nix = mx<w?mx:w2 - mx - 1
#define _cimg_correlate_y_mirror const int my = cimg::mod(iy,h2), niy = my<h?my:h2 - my - 1
#define _cimg_correlate_z_mirror const int mz = cimg::mod(iz,d2), niz = mz<d?mz:d2 - mz - 1

#define _cimg_correlate(boundary,access) \
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel)) \
          cimg_forXYZ(res,x,y,z) { \
            Ttfloat val = 0; \
            const t *pK = K._data; \
            cimg_forZ(_kernel,r) { _cimg_correlate_z; _cimg_correlate_z_##boundary; \
              cimg_forY(_kernel,q) { _cimg_correlate_y; _cimg_correlate_y_##boundary; \
                cimg_forX(_kernel,p) { _cimg_correlate_x; _cimg_correlate_x_##boundary; \
                  val+=*(pK++)*(access); \
                } \
              } \
            } \
            _resu(x,y,z,0,res_wh,res_whd) = val; \
          }

#define _cimg_correlate_n(boundary,access) \
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel)) \
          cimg_forXYZ(res,x,y,z) { \
            Ttfloat val = 0, N = 0; \
            const t *pK = K._data; \
            cimg_forZ(_kernel,r) { _cimg_correlate_z; _cimg_correlate_z_##boundary; \
              cimg_forY(_kernel,q) { _cimg_correlate_y; _cimg_correlate_y_##boundary; \
                cimg_forX(_kernel,p) { _cimg_correlate_x; _cimg_correlate_x_##boundary; \
                  Ttfloat _val = access; \
                  val+=*(pK++)*_val; \
                  _val*=_val; N+=_val; \
                } \
              } \
            } \
            N*=M2; _resu(x,y,z,0,res_wh,res_whd) = N?val/std::sqrt(N):0; \
          }

          if (is_normalized) { // Normalized convolution/correlation
            switch (boundary_conditions) {
            case 0 : // Dirichlet
              _cimg_correlate_n(dirichlet,is_in_x && is_in_y && is_in_z?I(ix,iy,iz,0,wh,whd):(T)0);
              break;
            case 1 : // Neumann
              _cimg_correlate_n(neumann,I(nix,niy,niz,0,wh,whd));
              break;
            case 2 : // Periodic
              _cimg_correlate_n(periodic,I(nix,niy,niz,0,wh,whd));
              break;
            case 3 : // Mirror
              _cimg_correlate_n(mirror,I(nix,niy,niz,0,wh,whd));
              break;
            }
          } else { // Standard convolution/correlation
            switch (boundary_conditions) {
            case 0 : // Dirichlet
              _cimg_correlate(dirichlet,is_in_x && is_in_y && is_in_z?I(ix,iy,iz,0,wh,whd):(T)0);
              break;
            case 1 : // Neumann
              _cimg_correlate(neumann,I(nix,niy,niz,0,wh,whd));
              break;
            case 2 : // Periodic
              _cimg_correlate(periodic,I(nix,niy,niz,0,wh,whd));
              break;
            case 3 : // Mirror
              _cimg_correlate(mirror,I(nix,niy,niz,0,wh,whd));
              break;
            }
          }
          if (channel_mode==2)
            cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(c/smin)+=_resu;
          else if (channel_mode==3)
            cimg_pragma_openmp(critical(_correlate)) res.get_shared_channel(0)+=_resu;

        } _cimg_abort_catch_openmp2
      }
      cimg_abort_test;
      return res;
    }

    //! Convolve the image with a kernel.
    /**
       \param kernel = the correlation kernel.
       \param boundary_conditions Boundary condition. Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param is_normalized = enable local normalization.
       \param channel_mode Channel processing mode.
                           Can be { 0=all | 1=one for one (default) | 2=partial sum | 3=full sum }.
       \param xcenter X-coordinate of the kernel center (~0U>>1 means 'centered').
       \param ycenter Y-coordinate of the kernel center (~0U>>1 means 'centered').
       \param zcenter Z-coordinate of the kernel center (~0U>>1 means 'centered').
       \param xstride Stride along the X-axis.
       \param ystride Stride along the Y-axis.
       \param zstride Stride along the Z-axis.
       \param xdilation Dilation along the X-axis.
       \param ydilation Dilation along the Y-axis.
       \param zdilation Dilation along the Z-axis.
       \param xoffset X-offset.
       \param yoffset Y-offset.
       \param zoffset Z-offset.
       \param xsize Width of the resulting image (~0U means 'instance_width/xstride').
       \param ysize Height of the resulting image (~0U means 'instance_height/ystride').
       \param zsize Depth of the resulting image (~0U means 'instance_depth/zstride').
       \note
       - The convolution of the image instance \p *this by the kernel \p kernel is defined to be:
       \f$ res(x,y,z) = sum_{i,j,k} (*this)(\alpha_x\;x - \beta_x\;(i - c_x),\alpha_y\;y
                    - \beta_y\;(j - c_y),\alpha_z\;z - \beta_z\;(k - c_z))*kernel(i,j,k) \f$.
    **/
    template<typename t>
    CImg<T>& convolve(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                      const bool is_normalized=false, const unsigned int channel_mode=1,
                      const int xcenter=(int)(~0U>>1),
                      const int ycenter=(int)(~0U>>1),
                      const int zcenter=(int)(~0U>>1),
                      const unsigned int xstride=1,
                      const unsigned int ystride=1,
                      const unsigned int zstride=1,
                      const int xdilation=1, const int ydilation=1, const int zdilation=1,
                      const int xoffset=0, const int yoffset=0, const int zoffset=0,
                      const unsigned int xsize=~0U,
                      const unsigned int ysize=~0U,
                      const unsigned int zsize=~0U) {
      if (is_empty() || !kernel) return *this;
      return get_convolve(kernel,boundary_conditions,is_normalized,channel_mode,
                          xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                          xoffset,yoffset,zoffset,xsize,ysize,zsize).move_to(*this);
    }

    //! Convolve the image with a kernel \newinstance.
    template<typename t>
    CImg<_cimg_Ttfloat> get_convolve(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                                     const bool is_normalized=false, const unsigned int channel_mode=1,
                                     const int xcenter=(int)(~0U>>1),
                                     const int ycenter=(int)(~0U>>1),
                                     const int zcenter=(int)(~0U>>1),
                                     const unsigned int xstride=1,
                                     const unsigned int ystride=1,
                                     const unsigned int zstride=1,
                                     const int xdilation=1, const int ydilation=1, const int zdilation=1,
                                     const int xoffset=0, const int yoffset=0, const int zoffset=0,
                                     const unsigned int xsize=~0U,
                                     const unsigned int ysize=~0U,
                                     const unsigned int zsize=~0U) const {
      return _correlate(kernel,boundary_conditions,is_normalized,channel_mode,
                        xcenter,ycenter,zcenter,xstride,ystride,zstride,xdilation,ydilation,zdilation,
                        xoffset,yoffset,zoffset,xsize,ysize,zsize,true);
    }

    //! Cumulate image values, optionally along specified axis.
    /**
       \param axis Cumulation axis. Set it to 0 to cumulate all values globally without taking axes into account.
    **/
    CImg<T>& cumulate(const char axis=0) {
      switch (cimg::lowercase(axis)) {
      case 'x' :
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forYZC(*this,y,z,c) {
          T *ptrd = data(0,y,z,c);
          Tlong cumul = (Tlong)0;
          cimg_forX(*this,x) { cumul+=(Tlong)*ptrd; *(ptrd++) = (T)cumul; }
        }
        break;
      case 'y' : {
        const ulongT w = (ulongT)_width;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_height>=(cimg_openmp_sizefactor)*512 &&
                                                                   _width*_depth*_spectrum>=16))
        cimg_forXZC(*this,x,z,c) {
          T *ptrd = data(x,0,z,c);
          Tlong cumul = (Tlong)0;
          cimg_forY(*this,y) { cumul+=(Tlong)*ptrd; *ptrd = (T)cumul; ptrd+=w; }
        }
      } break;
      case 'z' : {
        const ulongT wh = (ulongT)_width*_height;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_depth>=(cimg_openmp_sizefactor)*512 &&
                                                                   _width*_depth*_spectrum>=16))
        cimg_forXYC(*this,x,y,c) {
          T *ptrd = data(x,y,0,c);
          Tlong cumul = (Tlong)0;
          cimg_forZ(*this,z) { cumul+=(Tlong)*ptrd; *ptrd = (T)cumul; ptrd+=wh; }
        }
      } break;
      case 'c' : {
        const ulongT whd = (ulongT)_width*_height*_depth;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                           cimg_openmp_if(_spectrum>=(cimg_openmp_sizefactor)*512 && _width*_height*_depth>=16))
        cimg_forXYZ(*this,x,y,z) {
          T *ptrd = data(x,y,z,0);
          Tlong cumul = (Tlong)0;
          cimg_forC(*this,c) { cumul+=(Tlong)*ptrd; *ptrd = (T)cumul; ptrd+=whd; }
        }
      } break;
      default : { // Global cumulation
        Tlong cumul = (Tlong)0;
        cimg_for(*this,ptrd,T) { cumul+=(Tlong)*ptrd; *ptrd = (T)cumul; }
      }
      }
      return *this;
    }

    //! Cumulate image values, optionally along specified axis \newinstance.
    CImg<Tlong> get_cumulate(const char axis=0) const {
      return CImg<Tlong>(*this,false).cumulate(axis);
    }

    //! Cumulate image values, along specified axes.
    /**
       \param axes Cumulation axes, as a C-string.
       \note \c axes may contains multiple characters, e.g. \c "xyz"
    **/
    CImg<T>& cumulate(const char *const axes) {
      if (!axes) return cumulate();
      for (const char *s = axes; *s; ++s) cumulate(*s);
      return *this;
    }

    //! Cumulate image values, along specified axes \newinstance.
    CImg<Tlong> get_cumulate(const char *const axes) const {
      return CImg<Tlong>(*this,false).cumulate(axes);
    }

    //! Erode image by a structuring element.
    /**
       \param kernel Structuring element.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \param is_real Do the erosion in real (a.k.a 'non-flat') mode (\c true) rather than binary mode (\c false).
    **/
    template<typename t>
    CImg<T>& erode(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                   const bool is_real=false) {
      if (is_empty() || !kernel) return *this;
      return get_erode(kernel,boundary_conditions,is_real).move_to(*this);
    }

    //! Erode image by a structuring element \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_erode(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                             const bool is_real=false) const {
      if (is_empty() || !kernel) return *this;
      if (!is_real && kernel==0) return CImg<T>(width(),height(),depth(),spectrum(),0);
      typedef _cimg_Tt Tt;
      CImg<Tt> res(_width,_height,_depth,std::max(_spectrum,kernel._spectrum));
      const int
        mx2 = kernel.width()/2, my2 = kernel.height()/2, mz2 = kernel.depth()/2,
        mx1 = kernel.width() - mx2 - 1, my1 = kernel.height() - my2 - 1, mz1 = kernel.depth() - mz2 - 1,
        mxe = width() - mx2, mye = height() - my2, mze = depth() - mz2,
        w2 = 2*width(), h2 = 2*height(), d2 = 2*depth();
      const bool
        is_inner_parallel = _width*_height*_depth>=(cimg_openmp_sizefactor)*32768,
        is_outer_parallel = res.size()>=(cimg_openmp_sizefactor)*32768;
      cimg::unused(is_inner_parallel,is_outer_parallel);
      _cimg_abort_init_openmp;
      cimg_abort_init;
      cimg_pragma_openmp(parallel for cimg_openmp_if(!is_inner_parallel && is_outer_parallel))
      cimg_forC(res,c) _cimg_abort_try_openmp {
        cimg_abort_test;
        const CImg<T> img = get_shared_channel(c%_spectrum);
        const CImg<t> K = kernel.get_shared_channel(c%kernel._spectrum);
        if (is_real) { // Real erosion
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
          for (int z = mz1; z<mze; ++z)
            for (int y = my1; y<mye; ++y)
              for (int x = mx1; x<mxe; ++x) _cimg_abort_try_openmp2 {
                cimg_abort_test2;
                Tt min_val = cimg::type<Tt>::max();
                for (int zm = -mz1; zm<=mz2; ++zm)
                  for (int ym = -my1; ym<=my2; ++ym)
                    for (int xm = -mx1; xm<=mx2; ++xm) {
                      const t mval = K(mx1 + xm,my1 + ym,mz1 + zm);
                      const Tt cval = (Tt)(img(x + xm,y + ym,z + zm) - mval);
                      if (cval<min_val) min_val = cval;
                    }
                res(x,y,z,c) = min_val;
              } _cimg_abort_catch_openmp2

          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
          cimg_forYZ(res,y,z) _cimg_abort_try_openmp2 {
            cimg_abort_test2;
            for (int x = 0; x<width(); (y<my1 || y>=mye || z<mz1 || z>=mze)?++x:((x<mx1 - 1 || x>=mxe)?++x:(x=mxe))) {
              Tt min_val = cimg::type<Tt>::max();
              for (int zm = -mz1; zm<=mz2; ++zm)
                for (int ym = -my1; ym<=my2; ++ym)
                  for (int xm = -mx1; xm<=mx2; ++xm) {
                    const t mval = K(mx1 + xm,my1 + ym,mz1 + zm);
                    Tt cval;
                    switch (boundary_conditions) {
                    case 0 : cval = (Tt)(img.atXYZ(x + xm,y + ym,z + zm,0,(T)0) - mval); break;
                    case 1 : cval = (Tt)(img._atXYZ(x + xm,y + ym,z + zm) - mval); break;
                    case 2 : {
                      const int
                        nx = cimg::mod(x + xm,width()),
                        ny = cimg::mod(y + ym,height()),
                        nz = cimg::mod(z + zm,depth());
                      cval = img(nx,ny,nz) - mval;
                    } break;
                    default : {
                      const int
                        tx = cimg::mod(x + xm,w2),
                        ty = cimg::mod(y + ym,h2),
                        tz = cimg::mod(z + zm,d2),
                        nx = tx<width()?tx:w2 - tx - 1,
                        ny = ty<height()?ty:h2 - ty - 1,
                        nz = tz<depth()?tz:d2 - tz - 1;
                      cval = img(nx,ny,nz) - mval;
                    }
                    }
                    if (cval<min_val) min_val = cval;
                  }
              res(x,y,z,c) = min_val;
            }
          } _cimg_abort_catch_openmp2

        } else { // Binary erosion
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
          for (int z = mz1; z<mze; ++z)
            for (int y = my1; y<mye; ++y)
              for (int x = mx1; x<mxe; ++x) _cimg_abort_try_openmp2 {
                cimg_abort_test2;
                Tt min_val = cimg::type<Tt>::max();
                for (int zm = -mz1; zm<=mz2; ++zm)
                  for (int ym = -my1; ym<=my2; ++ym)
                    for (int xm = -mx1; xm<=mx2; ++xm)
                      if (K(mx1 + xm,my1 + ym,mz1 + zm)) {
                        const Tt cval = (Tt)img(x + xm,y + ym,z + zm);
                        if (cval<min_val) min_val = cval;
                      }
                res(x,y,z,c) = min_val;
              } _cimg_abort_catch_openmp2

          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
          cimg_forYZ(res,y,z) _cimg_abort_try_openmp2 {
            cimg_abort_test2;
            for (int x = 0; x<width(); (y<my1 || y>=mye || z<mz1 || z>=mze)?++x:((x<mx1 - 1 || x>=mxe)?++x:(x=mxe))) {
              Tt min_val = cimg::type<Tt>::max();
              for (int zm = -mz1; zm<=mz2; ++zm)
                for (int ym = -my1; ym<=my2; ++ym)
                  for (int xm = -mx1; xm<=mx2; ++xm) {
                    if (K(mx1 + xm,my1 + ym,mz1 + zm)) {
                      Tt cval;
                      switch (boundary_conditions) {
                      case 0 : cval = (Tt)img.atXYZ(x + xm,y + ym,z + zm,0,(T)0); break;
                      case 1 : cval = (Tt)img._atXYZ(x + xm,y + ym,z + zm); break;
                      case 2 : {
                        const int
                          nx = cimg::mod(x + xm,width()),
                          ny = cimg::mod(y + ym,height()),
                          nz = cimg::mod(z + zm,depth());
                        cval = img(nx,ny,nz);
                      } break;
                      default : {
                        const int
                          tx = cimg::mod(x + xm,w2),
                          ty = cimg::mod(y + ym,h2),
                          tz = cimg::mod(z + zm,d2),
                          nx = tx<width()?tx:w2 - tx - 1,
                          ny = ty<height()?ty:h2 - ty - 1,
                          nz = tz<depth()?tz:d2 - tz - 1;
                        cval = img(nx,ny,nz);
                      }
                      }
                      if (cval<min_val) min_val = cval;
                    }
                  }
              res(x,y,z,c) = min_val;
            }
          } _cimg_abort_catch_openmp2

        }
      } _cimg_abort_catch_openmp
      cimg_abort_test;
      return res;
    }

    //! Erode image by a rectangular structuring element of specified size.
    /**
       \param sx Width of the structuring element.
       \param sy Height of the structuring element.
       \param sz Depth of the structuring element.
    **/
    CImg<T>& erode(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      if (sx>1 && _width>1) { // Along X-axis
        const int L = width(), off = 1, s = (int)sx, _s2 = s/2 + 1, _s1 = s - _s2, s1 = _s1>L?L:_s1, s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forYZC(*this,y,z,c) {
          T *const ptrdb = buf._data, *ptrd = buf._data, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(0,y,z,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val<=cur) { cur = val; is_first = false; }}
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(0,y,z,c); cur = std::min(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val<=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval<cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval<cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val<=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val<cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val<cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(0,y,z,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }

      if (sy>1 && _height>1) { // Along Y-axis
        const int L = height(), off = width(), s = (int)sy, _s2 = s/2 + 1, _s1 = s - _s2, s1 = _s1>L?L:_s1,
          s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forXZC(*this,x,z,c) {
          T *const ptrdb = buf._data, *ptrd = ptrdb, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(x,0,z,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val<=cur) { cur = val; is_first = false; }
          }
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(x,0,z,c); cur = std::min(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val<=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval<cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval<cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val<=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val<cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val<cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(x,0,z,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }

      if (sz>1 && _depth>1) { // Along Z-axis
        const int L = depth(), off = width()*height(), s = (int)sz, _s2 = s/2 + 1, _s1 = s - _s2, s1 = _s1>L?L:_s1,
          s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forXYC(*this,x,y,c) {
          T *const ptrdb = buf._data, *ptrd = ptrdb, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(x,y,0,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val<=cur) { cur = val; is_first = false; }
          }
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(x,y,0,c); cur = std::min(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val<=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval<cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval<cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val<=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val<cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val<cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(x,y,0,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }
      return *this;
    }

    //! Erode image by a rectangular structuring element of specified size \newinstance.
    CImg<T> get_erode(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) const {
      return (+*this).erode(sx,sy,sz);
    }

    //! Erode the image by a square structuring element of specified size.
    /**
       \param s Size of the structuring element.
    **/
    CImg<T>& erode(const unsigned int s) {
      return erode(s,s,s);
    }

    //! Erode the image by a square structuring element of specified size \newinstance.
    CImg<T> get_erode(const unsigned int s) const {
      return (+*this).erode(s);
    }

    //! Dilate image by a structuring element.
    /**
       \param kernel Structuring element.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param is_real Do the dilation in real (a.k.a 'non-flat') mode (\c true) rather than binary mode (\c false).
    **/
    template<typename t>
    CImg<T>& dilate(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                    const bool is_real=false) {
      if (is_empty() || !kernel) return *this;
      return get_dilate(kernel,boundary_conditions,is_real).move_to(*this);
    }

    //! Dilate image by a structuring element \newinstance.
    template<typename t>
    CImg<_cimg_Tt> get_dilate(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                              const bool is_real=false) const {
      if (is_empty() || !kernel || (!is_real && kernel==0)) return *this;
      typedef _cimg_Tt Tt;
      CImg<Tt> res(_width,_height,_depth,std::max(_spectrum,kernel._spectrum));
      const int
        mx1 = kernel.width()/2, my1 = kernel.height()/2, mz1 = kernel.depth()/2,
        mx2 = kernel.width() - mx1 - 1, my2 = kernel.height() - my1 - 1, mz2 = kernel.depth() - mz1 - 1,
        mxe = width() - mx2, mye = height() - my2, mze = depth() - mz2,
        w2 = 2*width(), h2 = 2*height(), d2 = 2*depth();
      const bool
        is_inner_parallel = _width*_height*_depth>=(cimg_openmp_sizefactor)*32768,
        is_outer_parallel = res.size()>=(cimg_openmp_sizefactor)*32768;
      cimg::unused(is_inner_parallel,is_outer_parallel);
      _cimg_abort_init_openmp;
      cimg_abort_init;
      cimg_pragma_openmp(parallel for cimg_openmp_if(!is_inner_parallel && is_outer_parallel))
      cimg_forC(res,c) _cimg_abort_try_openmp {
        cimg_abort_test;
        const CImg<T> img = get_shared_channel(c%_spectrum);
        const CImg<t> K = kernel.get_shared_channel(c%kernel._spectrum);
        if (is_real) { // Real dilation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
          for (int z = mz1; z<mze; ++z)
            for (int y = my1; y<mye; ++y)
              for (int x = mx1; x<mxe; ++x) _cimg_abort_try_openmp2 {
                cimg_abort_test2;
                Tt max_val = cimg::type<Tt>::min();
                for (int zm = -mz1; zm<=mz2; ++zm)
                  for (int ym = -my1; ym<=my2; ++ym)
                    for (int xm = -mx1; xm<=mx2; ++xm) {
                      const t mval = K(mx2 - xm,my2 - ym,mz2 - zm);
                      const Tt cval = (Tt)(img(x + xm,y + ym,z + zm) + mval);
                      if (cval>max_val) max_val = cval;
                    }
                res(x,y,z,c) = max_val;
              } _cimg_abort_catch_openmp2

          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
          cimg_forYZ(res,y,z) _cimg_abort_try_openmp2 {
            cimg_abort_test2;
            for (int x = 0; x<width(); (y<my1 || y>=mye || z<mz1 || z>=mze)?++x:((x<mx1 - 1 || x>=mxe)?++x:(x=mxe))) {
              Tt max_val = cimg::type<Tt>::min();
              for (int zm = -mz1; zm<=mz2; ++zm)
                for (int ym = -my1; ym<=my2; ++ym)
                  for (int xm = -mx1; xm<=mx2; ++xm) {
                    const t mval = K(mx2 - xm,my2 - ym,mz2 - zm);
                    Tt cval;
                    switch (boundary_conditions) {
                    case 0 : cval = (Tt)(img.atXYZ(x + xm,y + ym,z + zm,0,(T)0) + mval); break;
                    case 1 : cval = (Tt)(img._atXYZ(x + xm,y + ym,z + zm) + mval); break;
                    case 2 : {
                      const int
                        nx = cimg::mod(x + xm,width()),
                        ny = cimg::mod(y + ym,height()),
                        nz = cimg::mod(z + zm,depth());
                      cval = img(nx,ny,nz) + mval;
                    } break;
                    default : {
                      const int
                        tx = cimg::mod(x + xm,w2),
                        ty = cimg::mod(y + ym,h2),
                        tz = cimg::mod(z + zm,d2),
                        nx = tx<width()?tx:w2 - tx - 1,
                        ny = ty<height()?ty:h2 - ty - 1,
                        nz = tz<depth()?tz:d2 - tz - 1;
                      cval = img(nx,ny,nz) + mval;
                    }
                    }
                    if (cval>max_val) max_val = cval;
                  }
              res(x,y,z,c) = max_val;
            }
          } _cimg_abort_catch_openmp2

        } else { // Binary dilation
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(is_inner_parallel))
          for (int z = mz1; z<mze; ++z)
            for (int y = my1; y<mye; ++y)
              for (int x = mx1; x<mxe; ++x) _cimg_abort_try_openmp2 {
                cimg_abort_test2;
                Tt max_val = cimg::type<Tt>::min();
                for (int zm = -mz1; zm<=mz2; ++zm)
                  for (int ym = -my1; ym<=my2; ++ym)
                    for (int xm = -mx1; xm<=mx2; ++xm)
                      if (K(mx2 - xm,my2 - ym,mz2 - zm)) {
                        const Tt cval = (Tt)img(x + xm,y + ym,z + zm);
                        if (cval>max_val) max_val = cval;
                      }
                res(x,y,z,c) = max_val;
              } _cimg_abort_catch_openmp2

          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(is_inner_parallel))
          cimg_forYZ(res,y,z) _cimg_abort_try_openmp2 {
            cimg_abort_test2;
            for (int x = 0; x<width(); (y<my1 || y>=mye || z<mz1 || z>=mze)?++x:((x<mx1 - 1 || x>=mxe)?++x:(x=mxe))) {
              Tt max_val = cimg::type<Tt>::min();
              for (int zm = -mz1; zm<=mz2; ++zm)
                for (int ym = -my1; ym<=my2; ++ym)
                  for (int xm = -mx1; xm<=mx2; ++xm) {
                    if (K(mx2 - xm,my2 - ym,mz2 - zm)) {
                      Tt cval;
                      switch (boundary_conditions) {
                      case 0 : cval = (Tt)img.atXYZ(x + xm,y + ym,z + zm,0,(T)0); break;
                      case 1 : cval = (Tt)img._atXYZ(x + xm,y + ym,z + zm); break;
                      case 2 : {
                        const int
                          nx = cimg::mod(x + xm,width()),
                          ny = cimg::mod(y + ym,height()),
                          nz = cimg::mod(z + zm,depth());
                        cval = img(nx,ny,nz);
                      } break;
                      default : {
                        const int
                          tx = cimg::mod(x + xm,w2),
                          ty = cimg::mod(y + ym,h2),
                          tz = cimg::mod(z + zm,d2),
                          nx = tx<width()?tx:w2 - tx - 1,
                          ny = ty<height()?ty:h2 - ty - 1,
                          nz = tz<depth()?tz:d2 - tz - 1;
                        cval = img(nx,ny,nz);
                      }
                      }
                      if (cval>max_val) max_val = cval;
                    }
                  }
              res(x,y,z,c) = max_val;
            }
          } _cimg_abort_catch_openmp2

        }
      } _cimg_abort_catch_openmp
      cimg_abort_test;
      return res;
    }

    //! Dilate image by a rectangular structuring element of specified size.
    /**
       \param sx Width of the structuring element.
       \param sy Height of the structuring element.
       \param sz Depth of the structuring element.
    **/
    CImg<T>& dilate(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      if (sx>1 && _width>1) { // Along X-axis
        const int L = width(), off = 1, s = (int)sx, _s1 = s/2, _s2 = s - _s1, s1 = _s1>L?L:_s1, s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forYZC(*this,y,z,c) {
          T *const ptrdb = buf._data, *ptrd = ptrdb, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(0,y,z,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
          }
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(0,y,z,c); cur = std::max(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval>cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval>cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val>=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val>cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val>cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(0,y,z,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }

      if (sy>1 && _height>1) { // Along Y-axis
        const int L = height(), off = width(), s = (int)sy, _s1 = s/2, _s2 = s - _s1, s1 = _s1>L?L:_s1,
          s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forXZC(*this,x,z,c) {
          T *const ptrdb = buf._data, *ptrd = ptrdb, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(x,0,z,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
          }
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(x,0,z,c); cur = std::max(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval>cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval>cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val>=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val>cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val>cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(x,0,z,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }

      if (sz>1 && _depth>1) { // Along Z-axis
        const int L = depth(), off = width()*height(), s = (int)sz, _s1 = s/2, _s2 = s - _s1, s1 = _s1>L?L:_s1,
          s2 = _s2>L?L:_s2;
        CImg<T> buf(L);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) firstprivate(buf) if (size()>524288))
        cimg_forXYC(*this,x,y,c) {
          T *const ptrdb = buf._data, *ptrd = ptrdb, *const ptrde = buf._data + L - 1;
          const T *const ptrsb = data(x,y,0,c), *ptrs = ptrsb, *const ptrse = ptrs + (ulongT)L*off - off;
          T cur = *ptrs; ptrs+=off; bool is_first = true;
          for (int p = s2 - 1; p>0 && ptrs<=ptrse; --p) {
            const T val = *ptrs; ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
          }
          *(ptrd++) = cur;
          if (ptrs>=ptrse) {
            T *pd = data(x,y,0,c); cur = std::max(cur,*ptrse); cimg_forX(buf,k) { *pd = cur; pd+=off; }
          } else {
            for (int p = s1; p>0 && ptrd<=ptrde; --p) {
              const T val = *ptrs; if (ptrs<ptrse) ptrs+=off; if (val>=cur) { cur = val; is_first = false; }
              *(ptrd++) = cur;
            }
            for (int p = L - s - 1; p>0; --p) {
              const T val = *ptrs; ptrs+=off;
              if (is_first) {
                const T *nptrs = ptrs - off; cur = val;
                for (int q = s - 2; q>0; --q) { nptrs-=off; const T nval = *nptrs; if (nval>cur) cur = nval; }
                nptrs-=off; const T nval = *nptrs; if (nval>cur) { cur = nval; is_first = true; } else is_first = false;
              } else { if (val>=cur) cur = val; else if (cur==*(ptrs-s*off)) is_first = true; }
              *(ptrd++) = cur;
            }
            ptrd = ptrde; ptrs = ptrse; cur = *ptrs; ptrs-=off;
            for (int p = s1; p>0 && ptrs>=ptrsb; --p) {
              const T val = *ptrs; ptrs-=off; if (val>cur) cur = val;
            }
            *(ptrd--) = cur;
            for (int p = s2 - 1; p>0 && ptrd>=ptrdb; --p) {
              const T val = *ptrs; if (ptrs>ptrsb) ptrs-=off; if (val>cur) cur = val; *(ptrd--) = cur;
            }
            T *pd = data(x,y,0,c); cimg_for(buf,ps,T) { *pd = *ps; pd+=off; }
          }
        }
      }
      return *this;
    }

    //! Dilate image by a rectangular structuring element of specified size \newinstance.
    CImg<T> get_dilate(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) const {
      return (+*this).dilate(sx,sy,sz);
    }

    //! Dilate image by a square structuring element of specified size.
    /**
       \param s Size of the structuring element.
    **/
    CImg<T>& dilate(const unsigned int s) {
      return dilate(s,s,s);
    }

    //! Dilate image by a square structuring element of specified size \newinstance.
    CImg<T> get_dilate(const unsigned int s) const {
      return (+*this).dilate(s);
    }

    //! Apply morphological closing by a structuring element.
    /**
       \param kernel Structuring element.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param is_real Do the closing in real (a.k.a 'non-flat') mode (\c true) rather than binary mode (\c false).
    **/
    template<typename t>
    CImg<T>& closing(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                     const bool is_real=false) {
      const int sx = kernel.width(), sy = kernel.height(), sz = kernel.depth();
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      return get_closing(kernel,boundary_conditions,is_real).move_to(*this);
    }

    //! Apply morphological closing by a structuring element \newinstance.
    template<typename t>
    CImg<T> get_closing(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                        const bool is_real=false) const {
      const int sx = kernel.width(), sy = kernel.height(), sz = kernel.depth();
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      const int sx1 = (int)(sx - 1)/2, sy1 = (int)(sy - 1)/2, sz1 = (int)(sz - 1)/2;
      CImg<T> res;
      if (_depth>1) { // 3D
        get_resize(width() + sx + 1,height() + sy + 1,depth() + sz + 1,spectrum(),0,boundary_conditions,0.5,0.5,0.5).
          dilate(kernel,1,is_real).erode(kernel,1,is_real).
          crop(sx1 + 1,sy1 + 1,sz1 + 1,sx1 + width(),sy1 + height(),sz1 + depth()).move_to(res);
      } else if (_height>1) { // 2D
        get_resize(width() + sx + 1,height() + sy + 1,1,spectrum(),0,boundary_conditions,0.5,0.5).
          dilate(kernel,1,is_real).erode(kernel,1,is_real).
          crop(sx1 + 1,sy1 + 1,sx1 + width(),sy1 + height()).move_to(res);
      } else if (_width>1) { // 1D
        get_resize(width() + sx + 1,1,1,spectrum(),0,boundary_conditions,0.5).
          dilate(kernel,1,is_real).erode(kernel,1,is_real).
          crop(sx1 + 1,sx1 + width()).move_to(res);
      }
      return res;
    }

    //! Apply morphological closing by a rectangular structuring element of specified size.
    CImg<T>& closing(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      return get_closing(sx,sy,sz).move_to(*this);
    }

    //! Apply morphological closing by a rectangular structuring element of specified size \newinstance.
    CImg<T> get_closing(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) const {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      const int sx1 = (int)(sx - 1)/2, sy1 = (int)(sy - 1)/2, sz1 = (int)(sz - 1)/2;
      CImg<T> res;
      if (_depth>1) { // 3D
        get_resize(width() + sx + 1,height() + sy + 1,depth() + sz + 1,spectrum(),0,1,0.5,0.5,0.5).
          dilate(sx,sy,sz).erode(sx,sy,sz).
          crop(sx1 + 1,sy1 + 1,sz1 + 1,sx1 + width(),sy1 + height(),sz1 + depth()).move_to(res);
      } else if (_height>1) { // 2D
        get_resize(width() + sx + 1,height() + sy + 1,1,spectrum(),0,1,0.5,0.5).
          dilate(sx,sy).erode(sx,sy).
          crop(sx1 + 1,sy1 + 1,sx1 + width(),sy1 + height()).move_to(res);
      } else if (_width>1) { // 1D
        get_resize(width() + sx + 1,1,1,spectrum(),0,1,0.5).
          dilate(sx,1).erode(sx,1).
          crop(sx1 + 1,sx1 + width()).move_to(res);
      }
      return res;
    }

    //! Apply morphological closing by a square structuring element of specified size.
    /**
       \param s Size of the structuring element.
    **/
    CImg<T>& closing(const unsigned int s) {
      return closing(s,s,s);
    }

    //! Apply morphological closing by a square structuring element of specified size \newinstance.
    CImg<T> get_closing(const unsigned int s) const {
      return (+*this).closing(s);
    }

    //! Apply morphological opening by a structuring element.
    /**
       \param kernel Structuring element.
       \param boundary_conditions Boundary conditions.
         Can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       \param is_real Do the opening in real (a.k.a 'non-flat') mode (\c true) rather than binary mode (\c false).
    **/
    template<typename t>
    CImg<T>& opening(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                     const bool is_real=false) {
      const int sx = kernel.width(), sy = kernel.height(), sz = kernel.depth();
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      return get_opening(kernel,boundary_conditions,is_real).move_to(*this);
    }

    //! Apply morphological opening by a structuring element \newinstance.
    template<typename t>
    CImg<T> get_opening(const CImg<t>& kernel, const unsigned int boundary_conditions=1,
                        const bool is_real=false) const {
      const int sx = kernel.width(), sy = kernel.height(), sz = kernel.depth();
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      const int sx1 = (int)(sx - 1)/2, sy1 = (int)(sy - 1)/2, sz1 = (int)(sz - 1)/2;
      CImg<T> res;
      if (_depth>1) { // 3D
        get_resize(width() + sx + 1,height() + sy + 1,depth() + sz + 1,spectrum(),0,boundary_conditions,0.5,0.5,0.5).
          erode(kernel,1,is_real).dilate(kernel,1,is_real).
          crop(sx1 + 1,sy1 + 1,sz1 + 1,sx1 + width(),sy1 + height(),sz1 + depth()).move_to(res);
      } else if (_height>1) { // 2D
        get_resize(width() + sx + 1,height() + sy + 1,1,spectrum(),0,boundary_conditions,0.5,0.5).
          erode(kernel,1,is_real).dilate(kernel,1,is_real).
          crop(sx1 + 1,sy1 + 1,sx1 + width(),sy1 + height()).move_to(res);
      } else if (_width>1) { // 1D
        get_resize(width() + sx + 1,1,1,spectrum(),0,boundary_conditions,0.5).
          erode(kernel,1,is_real).dilate(kernel,1,is_real).
          crop(sx1 + 1,sx1 + width()).move_to(res);
      }
      return res;
    }

    //! Apply morphological opening by a rectangular structuring element of specified size.
    CImg<T>& opening(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      return get_opening(sx,sy,sz).move_to(*this);
    }

    //! Apply morphological opening by a rectangular structuring element of specified size \newinstance.
    CImg<T> get_opening(const unsigned int sx, const unsigned int sy, const unsigned int sz=1) const {
      if (is_empty() || (sx<=1 && sy<=1 && sz<=1)) return *this;
      const int sx1 = (int)(sx - 1)/2, sy1 = (int)(sy - 1)/2, sz1 = (int)(sz - 1)/2;
      CImg<T> res;
      if (_depth>1) { // 3D
        get_resize(width() + sx + 1,height() + sy + 1,depth() + sz + 1,spectrum(),0,1,0.5,0.5,0.5).
          erode(sx,sy,sz).dilate(sx,sy,sz).
          crop(sx1 + 1,sy1 + 1,sz1 + 1,sx1 + width(),sy1 + height(),sz1 + depth()).move_to(res);
      } else if (_height>1) { // 2D
        get_resize(width() + sx + 1,height() + sy + 1,1,spectrum(),0,1,0.5,0.5).
          erode(sx,sy).dilate(sx,sy).
          crop(sx1 + 1,sy1 + 1,sx1 + width(),sy1 + height()).move_to(res);
      } else if (_width>1) { // 1D
        get_resize(width() + sx + 1,1,1,spectrum(),0,1,0.5).
          erode(sx,1).dilate(sx,1).
          crop(sx1 + 1,sx1 + width()).move_to(res);
      }
      return res;
    }

    //! Apply morphological opening by a square structuring element of specified size.
    /**
       \param s Size of the structuring element.
    **/
    CImg<T>& opening(const unsigned int s) {
      return opening(s,s,s);
    }

    //! Apply morphological opening by a square structuring element of specified size \newinstance.
    CImg<T> get_opening(const unsigned int s) const {
      return (+*this).opening(s);
    }

    //! Compute watershed transform.
    /**
       \param priority Priority map.
       \param is_high_connectivity Indicates whether the algorithm uses low or high connectivity.
       \note Non-zero values of the instance instance are propagated to zero-valued ones according to
       specified the priority map.
    **/
    template<typename t>
    CImg<T>& watershed(const CImg<t>& priority, const bool is_high_connectivity=false) {
#define _cimg_watershed_init(cond,X,Y,Z) \
      if (cond && !(*this)(X,Y,Z)) Q._priority_queue_insert(labels,sizeQ,priority(X,Y,Z),X,Y,Z,nb_seeds)

#define _cimg_watershed_propagate(cond,X,Y,Z) \
      if (cond) { \
        if ((*this)(X,Y,Z)) { \
          ns = labels(X,Y,Z) - 1; xs = seeds(ns,0); ys = seeds(ns,1); zs = seeds(ns,2); \
          d = cimg::sqr((float)x - xs) + cimg::sqr((float)y - ys) + cimg::sqr((float)z - zs); \
          if (d<dmin) { dmin = d; nmin = ns; nlabel = (*this)(xs,ys,zs); } \
        } else Q._priority_queue_insert(labels,sizeQ,priority(X,Y,Z),X,Y,Z,n); \
      }

      if (is_empty()) return *this;
      if (!is_sameXYZ(priority))
        throw CImgArgumentException(_cimg_instance
                                    "watershed(): image instance and specified priority (%u,%u,%u,%u,%p) "
                                    "have different dimensions.",
                                    cimg_instance,
                                    priority._width,priority._height,priority._depth,priority._spectrum,priority._data);
      if (_spectrum!=1) {
        cimg_forC(*this,c)
          get_shared_channel(c).watershed(priority.get_shared_channel(c%priority._spectrum));
        return *this;
      }

      CImg<uintT> labels(_width,_height,_depth,1,0), seeds(64,3);
      CImg<typename cimg::superset2<T,t,int>::type> Q;
      unsigned int sizeQ = 0;
      int px, nx, py, ny, pz, nz;
      bool is_px, is_nx, is_py, is_ny, is_pz, is_nz;
      const bool is_3d = _depth>1;

      // Find seed points and insert them in priority queue.
      unsigned int nb_seeds = 0;
      const T *ptrs = _data;
      cimg_forXYZ(*this,x,y,z) if (*(ptrs++)) { // 3D version
        if (nb_seeds>=seeds._width) seeds.resize(2*seeds._width,3,1,1,0);
        seeds(nb_seeds,0) = x; seeds(nb_seeds,1) = y; seeds(nb_seeds++,2) = z;
        px = x - 1; nx = x + 1;
        py = y - 1; ny = y + 1;
        pz = z - 1; nz = z + 1;
        is_px = px>=0; is_nx = nx<width();
        is_py = py>=0; is_ny = ny<height();
        is_pz = pz>=0; is_nz = nz<depth();
        _cimg_watershed_init(is_px,px,y,z);
        _cimg_watershed_init(is_nx,nx,y,z);
        _cimg_watershed_init(is_py,x,py,z);
        _cimg_watershed_init(is_ny,x,ny,z);
        if (is_3d) {
          _cimg_watershed_init(is_pz,x,y,pz);
          _cimg_watershed_init(is_nz,x,y,nz);
        }
        if (is_high_connectivity) {
          _cimg_watershed_init(is_px && is_py,px,py,z);
          _cimg_watershed_init(is_nx && is_py,nx,py,z);
          _cimg_watershed_init(is_px && is_ny,px,ny,z);
          _cimg_watershed_init(is_nx && is_ny,nx,ny,z);
          if (is_3d) {
            _cimg_watershed_init(is_px && is_pz,px,y,pz);
            _cimg_watershed_init(is_nx && is_pz,nx,y,pz);
            _cimg_watershed_init(is_px && is_nz,px,y,nz);
            _cimg_watershed_init(is_nx && is_nz,nx,y,nz);
            _cimg_watershed_init(is_py && is_pz,x,py,pz);
            _cimg_watershed_init(is_ny && is_pz,x,ny,pz);
            _cimg_watershed_init(is_py && is_nz,x,py,nz);
            _cimg_watershed_init(is_ny && is_nz,x,ny,nz);
            _cimg_watershed_init(is_px && is_py && is_pz,px,py,pz);
            _cimg_watershed_init(is_nx && is_py && is_pz,nx,py,pz);
            _cimg_watershed_init(is_px && is_ny && is_pz,px,ny,pz);
            _cimg_watershed_init(is_nx && is_ny && is_pz,nx,ny,pz);
            _cimg_watershed_init(is_px && is_py && is_nz,px,py,nz);
            _cimg_watershed_init(is_nx && is_py && is_nz,nx,py,nz);
            _cimg_watershed_init(is_px && is_ny && is_nz,px,ny,nz);
            _cimg_watershed_init(is_nx && is_ny && is_nz,nx,ny,nz);
          }
        }
        labels(x,y,z) = nb_seeds;
      }

      // Start watershed computation.
      while (sizeQ) {

        // Get and remove point with maximal priority from the queue.
        const int x = (int)Q(0,1), y = (int)Q(0,2), z = (int)Q(0,3);
        const unsigned int n = labels(x,y,z);
        px = x - 1; nx = x + 1;
        py = y - 1; ny = y + 1;
        pz = z - 1; nz = z + 1;
        is_px = px>=0; is_nx = nx<width();
        is_py = py>=0; is_ny = ny<height();
        is_pz = pz>=0; is_nz = nz<depth();

        // Check labels of the neighbors.
        Q._priority_queue_remove(sizeQ);

        unsigned int xs, ys, zs, ns, nmin = 0;
        float d, dmin = cimg::type<float>::inf();
        T nlabel = (T)0;
        _cimg_watershed_propagate(is_px,px,y,z);
        _cimg_watershed_propagate(is_nx,nx,y,z);
        _cimg_watershed_propagate(is_py,x,py,z);
        _cimg_watershed_propagate(is_ny,x,ny,z);
        if (is_3d) {
          _cimg_watershed_propagate(is_pz,x,y,pz);
          _cimg_watershed_propagate(is_nz,x,y,nz);
        }
        if (is_high_connectivity) {
          _cimg_watershed_propagate(is_px && is_py,px,py,z);
          _cimg_watershed_propagate(is_nx && is_py,nx,py,z);
          _cimg_watershed_propagate(is_px && is_ny,px,ny,z);
          _cimg_watershed_propagate(is_nx && is_ny,nx,ny,z);
          if (is_3d) {
            _cimg_watershed_propagate(is_px && is_pz,px,y,pz);
            _cimg_watershed_propagate(is_nx && is_pz,nx,y,pz);
            _cimg_watershed_propagate(is_px && is_nz,px,y,nz);
            _cimg_watershed_propagate(is_nx && is_nz,nx,y,nz);
            _cimg_watershed_propagate(is_py && is_pz,x,py,pz);
            _cimg_watershed_propagate(is_ny && is_pz,x,ny,pz);
            _cimg_watershed_propagate(is_py && is_nz,x,py,nz);
            _cimg_watershed_propagate(is_ny && is_nz,x,ny,nz);
            _cimg_watershed_propagate(is_px && is_py && is_pz,px,py,pz);
            _cimg_watershed_propagate(is_nx && is_py && is_pz,nx,py,pz);
            _cimg_watershed_propagate(is_px && is_ny && is_pz,px,ny,pz);
            _cimg_watershed_propagate(is_nx && is_ny && is_pz,nx,ny,pz);
            _cimg_watershed_propagate(is_px && is_py && is_nz,px,py,nz);
            _cimg_watershed_propagate(is_nx && is_py && is_nz,nx,py,nz);
            _cimg_watershed_propagate(is_px && is_ny && is_nz,px,ny,nz);
            _cimg_watershed_propagate(is_nx && is_ny && is_nz,nx,ny,nz);
          }
        }
        (*this)(x,y,z) = nlabel;
        labels(x,y,z) = ++nmin;
      }
      return *this;
    }

    //! Compute watershed transform \newinstance.
    template<typename t>
    CImg<T> get_watershed(const CImg<t>& priority, const bool is_high_connectivity=false) const {
      return (+*this).watershed(priority,is_high_connectivity);
    }

    // [internal] Insert/Remove items in priority queue, for watershed/distance transforms.
    template<typename tq, typename tv>
    bool _priority_queue_insert(CImg<tq>& is_queued, unsigned int& siz, const tv value,
                                const unsigned int x, const unsigned int y, const unsigned int z,
                                const unsigned int n=1) {
      if (is_queued(x,y,z)) return false;
      is_queued(x,y,z) = (tq)n;
      if (++siz>=_width) { if (!is_empty()) resize(_width*2,4,1,1,0); else assign(64,4); }
      (*this)(siz - 1,0) = (T)value;
      (*this)(siz - 1,1) = (T)x;
      (*this)(siz - 1,2) = (T)y;
      (*this)(siz - 1,3) = (T)z;
      for (unsigned int pos = siz - 1, par = 0; pos && value>(tv)(*this)(par=(pos + 1)/2 - 1,0); pos = par) {
        cimg::swap((*this)(pos,0),(*this)(par,0));
        cimg::swap((*this)(pos,1),(*this)(par,1));
        cimg::swap((*this)(pos,2),(*this)(par,2));
        cimg::swap((*this)(pos,3),(*this)(par,3));
      }
      return true;
    }

    CImg<T>& _priority_queue_remove(unsigned int& siz) {
      (*this)(0,0) = (*this)(--siz,0);
      (*this)(0,1) = (*this)(siz,1);
      (*this)(0,2) = (*this)(siz,2);
      (*this)(0,3) = (*this)(siz,3);
      const float value = (*this)(0,0);
      unsigned int pos = 0, swap = 0;
      do {
        const unsigned int left = 2*pos + 1, right = left + 1;
        if (right<siz && value<(*this)(right,0)) swap = (*this)(left,0)>(*this)(right,0)?left:right;
        else if (left<siz && value<(*this)(left,0)) swap = left;
        else break;
        cimg::swap((*this)(pos,0),(*this)(swap,0));
        cimg::swap((*this)(pos,1),(*this)(swap,1));
        cimg::swap((*this)(pos,2),(*this)(swap,2));
        cimg::swap((*this)(pos,3),(*this)(swap,3));
        pos = swap;
      } while (true);
      return *this;
    }

    //! Apply recursive Deriche filter.
    /**
       \param sigma Standard deviation of the filter.
       \param order Order of the filter. Can be <tt>{ 0=smooth-filter | 1=1st-derivative | 2=2nd-derivative }</tt>.
       \param axis Axis along which the filter is computed. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
    **/
    CImg<T>& deriche(const float sigma, const unsigned int order=0, const char axis='x',
                     const unsigned int boundary_conditions=1) {
#define _cimg_deriche_apply \
  CImg<doubleT> Y(N); \
  double *ptrY = Y._data, yb = 0, yp = 0; \
  T xp = (T)0; \
  if (boundary_conditions) { xp = *ptrX; yb = yp = (double)(coefp*xp); } \
  for (int m = 0; m<N; ++m) { \
    const T xc = *ptrX; ptrX+=off; \
    const double yc = *(ptrY++) = (double)(a0*xc + a1*xp - b1*yp - b2*yb); \
    xp = xc; yb = yp; yp = yc; \
  } \
  T xn = (T)0, xa = (T)0; \
  double yn = 0, ya = 0; \
  if (boundary_conditions) { xn = xa = *(ptrX - off); yn = ya = (double)coefn*xn; } \
  for (int n = N - 1; n>=0; --n) { \
    const T xc = *(ptrX-=off); \
    const double yc = (double)(a2*xn + a3*xa - b1*yn - b2*ya); \
    xa = xn; xn = xc; ya = yn; yn = yc; \
    *ptrX = (T)(*(--ptrY)+yc); \
  }

      if (order>2)
        throw CImgArgumentException(_cimg_instance
                                    "deriche(): Invalid specified order '%d' "
                                    "('order' can be { 0=smoothing | 1=1st-derivative | 2=2nd-derivative }).",
                                    cimg_instance,
                                    order);

      const char naxis = cimg::lowercase(axis);
      if (naxis!='x' && naxis!='y' && naxis!='z' && naxis!='c')
        throw CImgArgumentException(_cimg_instance
                                    "deriche(): Invalid specified axis '%c'.",
                                    cimg_instance,
                                    axis);
      const double
        nsigma = sigma>=0?sigma:-sigma*(naxis=='x'?_width:
                                        naxis=='y'?_height:
                                        naxis=='z'?_depth:_spectrum)/100,
        nnsigma = nsigma<0.1f?0.1f:nsigma;

      if (is_empty() || (nsigma<0.1f && !order)) return *this;
      if (boundary_conditions>1) {
        const int w = width(), h = height(), d = depth(), s = spectrum(), border = (int)cimg::round(1 + 3*nnsigma);
        switch (naxis) {
        case 'x' :
          return draw_image(get_resize(w + 2*border,h,d,s,0,boundary_conditions,0.5).
                            deriche(nnsigma,order,naxis,1).columns(border,w - 1 + border));
        case 'y' :
          return draw_image(get_resize(w,h + 2*border,d,s,0,boundary_conditions,0,0.5).
                            deriche(nnsigma,order,naxis,1).rows(border,h - 1 + border));
        case 'z' :
          return draw_image(get_resize(w,h,d + 2*border,s,0,boundary_conditions,0,0,0.5).
                            deriche(nnsigma,order,naxis,1).slices(border,d - 1 + border));
        default :
          return draw_image(get_resize(w,h,d,s + 2*border,0,boundary_conditions,0,0,0,0.5).
                            deriche(nnsigma,order,naxis,1).channels(border,d - 1 + border));
        }
      }

      const double
        alpha = 1.695f/nnsigma,
        ema = std::exp(-alpha),
        ema2 = std::exp(-2*alpha),
        b1 = -2*ema,
        b2 = ema2;
      double a0 = 0, a1 = 0, a2 = 0, a3 = 0, coefp = 0, coefn = 0;
      switch (order) {
      case 0 : {
        const double k = (1-ema)*(1-ema)/(1 + 2*alpha*ema-ema2);
        a0 = k;
        a1 = k*(alpha - 1)*ema;
        a2 = k*(alpha + 1)*ema;
        a3 = -k*ema2;
      } break;
      case 1 : {
        const double k = -(1-ema)*(1-ema)*(1-ema)/(2*(ema + 1)*ema);
        a0 = a3 = 0;
        a1 = k*ema;
        a2 = -a1;
      } break;
      default : {
        const double
          ea = std::exp(-alpha),
          k = -(ema2 - 1)/(2*alpha*ema),
          kn = (-2*(-1 + 3*ea - 3*ea*ea + ea*ea*ea)/(3*ea + 1 + 3*ea*ea + ea*ea*ea));
        a0 = kn;
        a1 = -kn*(1 + k*alpha)*ema;
        a2 = kn*(1 - k*alpha)*ema;
        a3 = -kn*ema2;
      } break;
      }

      coefp = (a0 + a1)/(1 + b1 + b2);
      coefn = (a2 + a3)/(1 + b1 + b2);
      switch (naxis) {
      case 'x' : {
        const int N = width();
        const ulongT off = 1U;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forYZC(*this,y,z,c) { T *ptrX = data(0,y,z,c); _cimg_deriche_apply; }
      } break;
      case 'y' : {
        const int N = height();
        const ulongT off = (ulongT)_width;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXZC(*this,x,z,c) { T *ptrX = data(x,0,z,c); _cimg_deriche_apply; }
      } break;
      case 'z' : {
        const int N = depth();
        const ulongT off = (ulongT)_width*_height;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYC(*this,x,y,c) { T *ptrX = data(x,y,0,c); _cimg_deriche_apply; }
      } break;
      default : {
        const int N = spectrum();
        const ulongT off = (ulongT)_width*_height*_depth;
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYZ(*this,x,y,z) { T *ptrX = data(x,y,z,0); _cimg_deriche_apply; }
      }
      }
      return *this;
    }

    //! Apply recursive Deriche filter \newinstance.
    CImg<Tfloat> get_deriche(const float sigma, const unsigned int order=0, const char axis='x',
                             const unsigned int boundary_conditions=1) const {
      return CImg<Tfloat>(*this,false).deriche(sigma,order,axis,boundary_conditions);
    }

    // [internal] Apply a recursive filter (used by CImg<T>::vanvliet()).
    /*
       \param ptr the pointer of the data
       \param filter the coefficient of the filter in the following order [n,n - 1,n - 2,n - 3].
       \param N size of the data
       \param off the offset between two data point
       \param order the order of the filter 0 (smoothing), 1st derivative, 2nd derivative, 3rd derivative
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann }</tt>.
       \note Boundary condition using B. Triggs method (IEEE trans on Sig Proc 2005).
    */
    static void _cimg_recursive_apply(T *data, const double filter[], const int N, const ulongT off,
                                      const unsigned int order, const bool boundary_conditions) {
      double val[4] = {}; // res[n,n - 1,n - 2,n - 3,..] or res[n,n + 1,n + 2,n + 3,..]
      const double
        sumsq = filter[0], sum = sumsq * sumsq,
        a1 = filter[1], a2 = filter[2], a3 = filter[3],
        scaleM = 1. / ( (1. + a1 - a2 + a3) * (1. - a1 - a2 - a3) * (1. + a2 + (a1 - a3) * a3) );
      double M[9]; // Triggs matrix
      M[0] = scaleM * (-a3 * a1 + 1. - a3 * a3 - a2);
      M[1] = scaleM * (a3 + a1) * (a2 + a3 * a1);
      M[2] = scaleM * a3 * (a1 + a3 * a2);
      M[3] = scaleM * (a1 + a3 * a2);
      M[4] = -scaleM * (a2 - 1.) * (a2 + a3 * a1);
      M[5] = -scaleM * a3 * (a3 * a1 + a3 * a3 + a2 - 1.);
      M[6] = scaleM * (a3 * a1 + a2 + a1 * a1 - a2 * a2);
      M[7] = scaleM * (a1 * a2 + a3 * a2 * a2 - a1 * a3 * a3 - a3 * a3 * a3 - a3 * a2 + a3);
      M[8] = scaleM * a3 * (a1 + a3 * a2);
      switch (order) {
      case 0 : {
        const double iplus = (boundary_conditions?data[(N - 1)*off]:(T)0);
        for (int pass = 0; pass<2; ++pass) {
          if (!pass) {
            for (int k = 1; k<4; ++k) val[k] = (boundary_conditions?*data/sumsq:0);
          } else {
            // Apply Triggs boundary conditions.
            const double
              uplus = iplus/(1. - a1 - a2 - a3), vplus = uplus/(1. - a1 - a2 - a3),
              unp  = val[1] - uplus, unp1 = val[2] - uplus, unp2 = val[3] - uplus;
            val[0] = (M[0] * unp + M[1] * unp1 + M[2] * unp2 + vplus) * sum;
            val[1] = (M[3] * unp + M[4] * unp1 + M[5] * unp2 + vplus) * sum;
            val[2] = (M[6] * unp + M[7] * unp1 + M[8] * unp2 + vplus) * sum;
            *data = (T)val[0];
            data -= off;
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          for (int n = pass; n<N; ++n) {
            val[0] = (*data);
            if (pass) val[0] *= sum;
            for (int k = 1; k<4; ++k) val[0] += val[k] * filter[k];
            *data = (T)val[0];
            if (!pass) data += off; else data -= off;
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          if (!pass) data -= off;
        }
      } break;
      case 1 : {
        double x[3]; // [front,center,back]
        for (int pass = 0; pass<2; ++pass) {
          if (!pass) {
            for (int k = 0; k<3; ++k) x[k] = (boundary_conditions?*data:(T)0);
            for (int k = 0; k<4; ++k) val[k] = 0;
          } else {
            // Apply Triggs boundary conditions.
            const double
              unp  = val[1], unp1 = val[2], unp2 = val[3];
            val[0] = (M[0] * unp + M[1] * unp1 + M[2] * unp2) * sum;
            val[1] = (M[3] * unp + M[4] * unp1 + M[5] * unp2) * sum;
            val[2] = (M[6] * unp + M[7] * unp1 + M[8] * unp2) * sum;
            *data = (T)val[0];
            data -= off;
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          for (int n = pass; n<N - 1; ++n) {
            if (!pass) {
              x[0] = *(data + off);
              val[0] = 0.5f * (x[0] - x[2]);
            } else val[0] = (*data) * sum;
            for (int k = 1; k<4; ++k) val[0] += val[k] * filter[k];
            *data = (T)val[0];
            if (!pass) {
              data += off;
              for (int k = 2; k>0; --k) x[k] = x[k - 1];
            } else { data-=off;}
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          *data = (T)0;
        }
      } break;
      case 2: {
        double x[3]; // [front,center,back]
        for (int pass = 0; pass<2; ++pass) {
          if (!pass) {
            for (int k = 0; k<3; ++k) x[k] = (boundary_conditions?*data:(T)0);
            for (int k = 0; k<4; ++k) val[k] = 0;
          } else {
            // Apply Triggs boundary conditions.
            const double
              unp  = val[1], unp1 = val[2], unp2 = val[3];
            val[0] = (M[0] * unp + M[1] * unp1 + M[2] * unp2) * sum;
            val[1] = (M[3] * unp + M[4] * unp1 + M[5] * unp2) * sum;
            val[2] = (M[6] * unp + M[7] * unp1 + M[8] * unp2) * sum;
            *data = (T)val[0];
            data -= off;
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          for (int n = pass; n<N - 1; ++n) {
            if (!pass) { x[0] = *(data + off); val[0] = (x[1] - x[2]); }
            else { x[0] = *(data - off); val[0] = (x[2] - x[1]) * sum; }
            for (int k = 1; k<4; ++k) val[0] += val[k]*filter[k];
            *data = (T)val[0];
            if (!pass) data += off; else data -= off;
            for (int k = 2; k>0; --k) x[k] = x[k - 1];
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          *data = (T)0;
        }
      } break;
      case 3: {
        double x[3]; // [front,center,back]
        for (int pass = 0; pass<2; ++pass) {
          if (!pass) {
            for (int k = 0; k<3; ++k) x[k] = (boundary_conditions?*data:(T)0);
            for (int k = 0; k<4; ++k) val[k] = 0;
          } else {
            // Apply Triggs boundary conditions.
            const double
              unp = val[1], unp1 = val[2], unp2 = val[3];
            val[0] = (M[0] * unp + M[1] * unp1 + M[2] * unp2) * sum;
            val[1] = (M[3] * unp + M[4] * unp1 + M[5] * unp2) * sum;
            val[2] = (M[6] * unp + M[7] * unp1 + M[8] * unp2) * sum;
            *data = (T)val[0];
            data -= off;
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          for (int n = pass; n<N - 1; ++n) {
            if (!pass) { x[0] = *(data + off); val[0] = (x[0] - 2*x[1] + x[2]); }
            else { x[0] = *(data - off); val[0] = 0.5f * (x[2] - x[0]) * sum; }
            for (int k = 1; k<4; ++k) val[0] += val[k] * filter[k];
            *data = (T)val[0];
            if (!pass) data += off; else data -= off;
            for (int k = 2; k>0; --k) x[k] = x[k - 1];
            for (int k = 3; k>0; --k) val[k] = val[k - 1];
          }
          *data = (T)0;
        }
      } break;
      }
    }

    //! Van Vliet recursive Gaussian filter.
    /**
       \param sigma standard deviation of the Gaussian filter
       \param order the order of the filter 0,1,2,3
       \param axis  Axis along which the filter is computed. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \note dirichlet boundary condition has a strange behavior

       I.T. Young, L.J. van Vliet, M. van Ginkel, Recursive Gabor filtering.
       IEEE Trans. Sig. Proc., vol. 50, pp. 2799-2805, 2002.

       (this is an improvement over Young-Van Vliet, Sig. Proc. 44, 1995)

       Boundary conditions (only for order 0) using Triggs matrix, from
       B. Triggs and M. Sdika. Boundary conditions for Young-van Vliet
       recursive filtering. IEEE Trans. Signal Processing,
       vol. 54, pp. 2365-2367, 2006.
    **/
    CImg<T>& vanvliet(const float sigma, const unsigned int order, const char axis='x',
                      const unsigned int boundary_conditions=1) {

      if (order>2)
        throw CImgArgumentException(_cimg_instance
                                    "deriche(): Invalid specified order '%d' "
                                    "('order' can be { 0=smoothing | 1=1st-derivative | 2=2nd-derivative }).",
                                    cimg_instance,
                                    order);

      const char naxis = cimg::lowercase(axis);
      if (naxis!='x' && naxis!='y' && naxis!='z' && naxis!='c')
        throw CImgArgumentException(_cimg_instance
                                    "deriche(): Invalid specified axis '%c'.",
                                    cimg_instance,
                                    axis);
      const double
        nsigma = sigma>=0?sigma:-sigma*(naxis=='x'?_width:
                                        naxis=='y'?_height:
                                        naxis=='z'?_depth:_spectrum)/100,
        nnsigma = nsigma<0.5f?0.5f:nsigma;

      if (is_empty() || (nsigma<0.1f && !order)) return *this;
      if (nsigma<0.5f) return deriche(nsigma,order,axis,boundary_conditions);
      if (!cimg::type<T>::is_float()
#if cimg_is_float16==1
          || cimg::type<T>::string()==cimg::type<cimg_float16>::string()
#endif
          )
        return CImg<Tfloat>(*this,false).vanvliet(sigma,order,axis,boundary_conditions).move_to(*this);

      if (boundary_conditions>1) {
        const int w = width(), h = height(), d = depth(), s = spectrum(), border = (int)cimg::round(1 + 3*nnsigma);
        switch (naxis) {
        case 'x' :
          return draw_image(get_resize(w + 2*border,h,d,s,0,boundary_conditions,0.5).
                            vanvliet(nnsigma,order,naxis,1).columns(border,w - 1 + border));
        case 'y' :
          return draw_image(get_resize(w,h + 2*border,d,s,0,boundary_conditions,0,0.5).
                            vanvliet(nnsigma,order,naxis,1).rows(border,h - 1 + border));
        case 'z' :
          return draw_image(get_resize(w,h,d + 2*border,s,0,boundary_conditions,0,0,0.5).
                            vanvliet(nnsigma,order,naxis,1).slices(border,d - 1 + border));
        default :
          return draw_image(get_resize(w,h,d,s + 2*border,0,boundary_conditions,0,0,0,0.5).
                            vanvliet(nnsigma,order,naxis,1).channels(border,d - 1 + border));
        }
      }

      const double
        m0 = 1.16680, m1 = 1.10783, m2 = 1.40586,
        m1sq = m1 * m1, m2sq = m2 * m2,
        q = (nnsigma<3.556?-0.2568 + 0.5784*nnsigma + 0.0561*nnsigma*nnsigma:2.5091 + 0.9804*(nnsigma - 3.556)),
        qsq = q * q,
        scale = (m0 + q) * (m1sq + m2sq + 2 * m1 * q + qsq),
        b1 = -q * (2 * m0 * m1 + m1sq + m2sq + (2 * m0 + 4 * m1) * q + 3 * qsq) / scale,
        b2 = qsq * (m0 + 2 * m1 + 3 * q) / scale,
        b3 = -qsq * q / scale,
        B = ( m0 * (m1sq + m2sq) ) / scale;
      double filter[4];
      filter[0] = B; filter[1] = -b1; filter[2] = -b2; filter[3] = -b3;
      switch (naxis) {
      case 'x' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forYZC(*this,y,z,c)
          _cimg_recursive_apply(data(0,y,z,c),filter,_width,1U,order,boundary_conditions);
      } break;
      case 'y' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXZC(*this,x,z,c)
          _cimg_recursive_apply(data(x,0,z,c),filter,_height,(ulongT)_width,order,boundary_conditions);
      } break;
      case 'z' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYC(*this,x,y,c)
          _cimg_recursive_apply(data(x,y,0,c),filter,_depth,(ulongT)_width*_height,
                                order,boundary_conditions);
      } break;
      default : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYZ(*this,x,y,z)
          _cimg_recursive_apply(data(x,y,z,0),filter,_spectrum,(ulongT)_width*_height*_depth,
                                order,boundary_conditions);
      }
      }
      return *this;
    }

    //! Blur image using Van Vliet recursive Gaussian filter. \newinstance.
    CImg<Tfloat> get_vanvliet(const float sigma, const unsigned int order, const char axis='x',
                              const unsigned int boundary_conditions=1) const {
      return CImg<Tfloat>(*this,false).vanvliet(sigma,order,axis,boundary_conditions);
    }

    //! Blur image.
    /**
       \param sigma_x Standard deviation of the blur, along the X-axis.
       \param sigma_y Standard deviation of the blur, along the Y-axis.
       \param sigma_z Standard deviation of the blur, along the Z-axis.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \param is_gaussian Indicates whether the blur uses a gaussian (\c true) or quasi-gaussian (\c false) kernel.
       \note
       - The blur is computed as a 0-order Vanvliet (gaussian) or Deriche filter (quasi-gaussian).
       - This is a recursive algorithm, not depending on the values of the standard deviations.
       \see deriche(), vanvliet().
    **/
    CImg<T>& blur(const float sigma_x, const float sigma_y, const float sigma_z,
                  const unsigned int boundary_conditions=1, const bool is_gaussian=true) {
      if (is_empty()) return *this;
      if (is_gaussian) {
        if (_width>1) vanvliet(sigma_x,0,'x',boundary_conditions);
        if (_height>1) vanvliet(sigma_y,0,'y',boundary_conditions);
        if (_depth>1) vanvliet(sigma_z,0,'z',boundary_conditions);
      } else {
        if (_width>1) deriche(sigma_x,0,'x',boundary_conditions);
        if (_height>1) deriche(sigma_y,0,'y',boundary_conditions);
        if (_depth>1) deriche(sigma_z,0,'z',boundary_conditions);
      }
      return *this;
    }

    //! Blur image \newinstance.
    CImg<Tfloat> get_blur(const float sigma_x, const float sigma_y, const float sigma_z,
                          const unsigned int boundary_conditions=1, const bool is_gaussian=true) const {
      return CImg<Tfloat>(*this,false).blur(sigma_x,sigma_y,sigma_z,boundary_conditions,is_gaussian);
    }

    //! Blur image isotropically.
    /**
       \param sigma Standard deviation of the blur.
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \param is_gaussian Use a gaussian kernel (VanVliet) is set, a quasi-gaussian (Deriche) otherwise.
       \see deriche(), vanvliet().
    **/
    CImg<T>& blur(const float sigma, const unsigned int boundary_conditions=1, const bool is_gaussian=true) {
      const float nsigma = sigma>=0?sigma:-sigma*cimg::max(_width,_height,_depth)/100;
      return blur(nsigma,nsigma,nsigma,boundary_conditions,is_gaussian);
    }

    //! Blur image isotropically \newinstance.
    CImg<Tfloat> get_blur(const float sigma, const unsigned int boundary_conditions=1,
                          const bool is_gaussian=true) const {
      return CImg<Tfloat>(*this,false).blur(sigma,boundary_conditions,is_gaussian);
    }

    //! Blur image anisotropically, directed by a field of diffusion tensors.
    /**
       \param G Field of square roots of diffusion tensors/vectors used to drive the smoothing.
       \param amplitude Amplitude of the smoothing.
       \param dl Spatial discretization.
       \param da Angular discretization.
       \param gauss_prec Precision of the diffusion process.
       \param interpolation_type Interpolation scheme.
         Can be <tt>{ 0=nearest-neighbor | 1=linear | 2=Runge-Kutta }</tt>.
       \param is_fast_approx Indicates whether a fast approximation of the gaussian function is used.
    **/
    template<typename t>
    CImg<T>& blur_anisotropic(const CImg<t>& G,
                              const float amplitude=60, const float dl=0.8f, const float da=30,
                              const float gauss_prec=2, const unsigned int interpolation_type=0,
                              const bool is_fast_approx=1) {

      // Check arguments and init variables.
      if (!is_sameXYZ(G) || (G._spectrum!=3 && G._spectrum!=6))
        throw CImgArgumentException(_cimg_instance
                                    "blur_anisotropic(): Invalid specified diffusion tensor field (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    G._width,G._height,G._depth,G._spectrum,G._data);
      if (is_empty() || dl<0) return *this;
      const float namplitude = amplitude>=0?amplitude:-amplitude*cimg::max(_width,_height,_depth)/100;
      unsigned int iamplitude = cimg::round(namplitude);
      const bool is_3d = (G._spectrum==6);
      T val_min, val_max = max_min(val_min);
      _cimg_abort_init_openmp;
      cimg_abort_init;

      if (da<=0) { // Iterated oriented Laplacians
        CImg<Tfloat> velocity(_width,_height,_depth,_spectrum);
        for (unsigned int iteration = 0; iteration<iamplitude; ++iteration) {
          Tfloat *ptrd = velocity._data, veloc_max = 0;
          if (is_3d) // 3D version
            cimg_forC(*this,c) {
              cimg_abort_test;
              CImg_3x3x3(I,Tfloat);
              cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) {
                const Tfloat
                  ixx = Incc + Ipcc - 2*Iccc,
                  ixy = (Innc + Ippc - Inpc - Ipnc)/4,
                  ixz = (Incn + Ipcp - Incp - Ipcn)/4,
                  iyy = Icnc + Icpc - 2*Iccc,
                  iyz = (Icnn + Icpp - Icnp - Icpn)/4,
                  izz = Iccn + Iccp - 2*Iccc,
                  veloc = (Tfloat)(G(x,y,z,0)*ixx + 2*G(x,y,z,1)*ixy + 2*G(x,y,z,2)*ixz +
                                   G(x,y,z,3)*iyy + 2*G(x,y,z,4)*iyz + G(x,y,z,5)*izz);
                *(ptrd++) = veloc;
                if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
              }
            }
          else // 2D version
            cimg_forZC(*this,z,c) {
              cimg_abort_test;
              CImg_3x3(I,Tfloat);
              cimg_for3x3(*this,x,y,z,c,I,Tfloat) {
                const Tfloat
                  ixx = Inc + Ipc - 2*Icc,
                  ixy = (Inn + Ipp - Inp - Ipn)/4,
                  iyy = Icn + Icp - 2*Icc,
                  veloc = (Tfloat)(G(x,y,0,0)*ixx + 2*G(x,y,0,1)*ixy + G(x,y,0,2)*iyy);
                *(ptrd++) = veloc;
                if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
              }
            }
          if (veloc_max>0) *this+=(velocity*=dl/veloc_max);
        }
      } else { // LIC-based smoothing
        const ulongT whd = (ulongT)_width*_height*_depth;
        const float sqrt2amplitude = (float)std::sqrt(2*namplitude);
        const int dx1 = width() - 1, dy1 = height() - 1, dz1 = depth() - 1;
        CImg<Tfloat> res(_width,_height,_depth,_spectrum,0), W(_width,_height,_depth,is_3d?4:3), val(_spectrum,1,1,1,0);
        int N = 0;
        if (is_3d) { // 3D version
          for (float phi = cimg::mod(180.f,da)/2.f; phi<=180; phi+=da) {
            const float phir = (float)(phi*cimg::PI/180), datmp = (float)(da/std::cos(phir)),
              da2 = datmp<1?360.f:datmp;
            for (float theta = 0; theta<360; (theta+=da2),++N) {
              const float
                thetar = (float)(theta*cimg::PI/180),
                vx = (float)(std::cos(thetar)*std::cos(phir)),
                vy = (float)(std::sin(thetar)*std::cos(phir)),
                vz = (float)std::sin(phir);
              const t
                *pa = G.data(0,0,0,0), *pb = G.data(0,0,0,1), *pc = G.data(0,0,0,2),
                *pd = G.data(0,0,0,3), *pe = G.data(0,0,0,4), *pf = G.data(0,0,0,5);
              Tfloat *pd0 = W.data(0,0,0,0), *pd1 = W.data(0,0,0,1), *pd2 = W.data(0,0,0,2), *pd3 = W.data(0,0,0,3);
              cimg_forXYZ(G,xg,yg,zg) {
                const t a = *(pa++), b = *(pb++), c = *(pc++), d = *(pd++), e = *(pe++), f = *(pf++);
                const float
                  u = (float)(a*vx + b*vy + c*vz),
                  v = (float)(b*vx + d*vy + e*vz),
                  w = (float)(c*vx + e*vy + f*vz),
                  n = 1e-5f + cimg::hypot(u,v,w),
                  dln = dl/n;
                *(pd0++) = (Tfloat)(u*dln);
                *(pd1++) = (Tfloat)(v*dln);
                *(pd2++) = (Tfloat)(w*dln);
                *(pd3++) = (Tfloat)n;
              }

              cimg_abort_test;
              cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                                 cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 && _height*_depth>=2)
                                 firstprivate(val))
              cimg_forYZ(*this,y,z) _cimg_abort_try_openmp2 {
                cimg_abort_test2;
                cimg_forX(*this,x) {
                  val.fill(0);
                  const float
                    n = (float)W(x,y,z,3),
                    fsigma = (float)(n*sqrt2amplitude),
                    fsigma2 = 2*fsigma*fsigma,
                    length = gauss_prec*fsigma;
                  float
                    S = 0,
                    X = (float)x,
                    Y = (float)y,
                    Z = (float)z;
                  switch (interpolation_type) {
                  case 0 : { // Nearest neighbor
                    for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1 && Z>=0 && Z<=dz1; l+=dl) {
                      const int
                        cx = (int)(X + 0.5f),
                        cy = (int)(Y + 0.5f),
                        cz = (int)(Z + 0.5f);
                      const float
                        u = (float)W(cx,cy,cz,0),
                        v = (float)W(cx,cy,cz,1),
                        w = (float)W(cx,cy,cz,2);
                      if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)(*this)(cx,cy,cz,c); ++S; }
                      else {
                        const float coef = (float)std::exp(-l*l/fsigma2);
                        cimg_forC(*this,c) val[c]+=(Tfloat)(coef*(*this)(cx,cy,cz,c));
                        S+=coef;
                      }
                      X+=u; Y+=v; Z+=w;
                    }
                  } break;
                  case 1 : { // Linear interpolation
                    for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1 && Z>=0 && Z<=dz1; l+=dl) {
                      const float
                        u = (float)(W._linear_atXYZ(X,Y,Z,0)),
                        v = (float)(W._linear_atXYZ(X,Y,Z,1)),
                        w = (float)(W._linear_atXYZ(X,Y,Z,2));
                      if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)_linear_atXYZ(X,Y,Z,c); ++S; }
                      else {
                        const float coef = (float)std::exp(-l*l/fsigma2);
                        cimg_forC(*this,c) val[c]+=(Tfloat)(coef*_linear_atXYZ(X,Y,Z,c));
                        S+=coef;
                      }
                      X+=u; Y+=v; Z+=w;
                    }
                  } break;
                  default : { // 2nd order Runge Kutta
                    for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1 && Z>=0 && Z<=dz1; l+=dl) {
                      const float
                        u0 = (float)(0.5f*W._linear_atXYZ(X,Y,Z,0)),
                        v0 = (float)(0.5f*W._linear_atXYZ(X,Y,Z,1)),
                        w0 = (float)(0.5f*W._linear_atXYZ(X,Y,Z,2)),
                        u = (float)(W._linear_atXYZ(X + u0,Y + v0,Z + w0,0)),
                        v = (float)(W._linear_atXYZ(X + u0,Y + v0,Z + w0,1)),
                        w = (float)(W._linear_atXYZ(X + u0,Y + v0,Z + w0,2));
                      if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)_linear_atXYZ(X,Y,Z,c); ++S; }
                      else {
                        const float coef = (float)std::exp(-l*l/fsigma2);
                        cimg_forC(*this,c) val[c]+=(Tfloat)(coef*_linear_atXYZ(X,Y,Z,c));
                        S+=coef;
                      }
                      X+=u; Y+=v; Z+=w;
                    }
                  } break;
                  }
                  Tfloat *ptrd = res.data(x,y,z);
                  if (S>0) cimg_forC(res,c) { *ptrd+=val[c]/S; ptrd+=whd; }
                  else cimg_forC(res,c) { *ptrd+=(Tfloat)((*this)(x,y,z,c)); ptrd+=whd; }
                }
              } _cimg_abort_catch_openmp2
            }
          }
        } else { // 2D LIC algorithm
          for (float theta = cimg::mod(360.f,da)/2.f; theta<360; (theta+=da),++N) {
            const float thetar = (float)(theta*cimg::PI/180),
              vx = (float)(std::cos(thetar)), vy = (float)(std::sin(thetar));
            const t *pa = G.data(0,0,0,0), *pb = G.data(0,0,0,1), *pc = G.data(0,0,0,2);
            Tfloat *pd0 = W.data(0,0,0,0), *pd1 = W.data(0,0,0,1), *pd2 = W.data(0,0,0,2);
            cimg_forXY(G,xg,yg) {
              const t a = *(pa++), b = *(pb++), c = *(pc++);
              const float
                u = (float)(a*vx + b*vy),
                v = (float)(b*vx + c*vy),
                n = std::max(1e-5f,cimg::hypot(u,v)),
                dln = dl/n;
              *(pd0++) = (Tfloat)(u*dln);
              *(pd1++) = (Tfloat)(v*dln);
              *(pd2++) = (Tfloat)n;
            }

            cimg_abort_test;
            cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 && _height>=2)
                               firstprivate(val))
            cimg_forY(*this,y) _cimg_abort_try_openmp2 {
              cimg_abort_test2;
              cimg_forX(*this,x) {
                val.fill(0);
                const float
                  n = (float)W(x,y,0,2),
                  fsigma = (float)(n*sqrt2amplitude),
                  fsigma2 = 2*fsigma*fsigma,
                  length = gauss_prec*fsigma;
                float
                  S = 0,
                  X = (float)x,
                  Y = (float)y;
                switch (interpolation_type) {
                case 0 : { // Nearest-neighbor
                  for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1; l+=dl) {
                    const int
                      cx = (int)(X + 0.5f),
                      cy = (int)(Y + 0.5f);
                    const float
                      u = (float)W(cx,cy,0,0),
                      v = (float)W(cx,cy,0,1);
                    if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)(*this)(cx,cy,0,c); ++S; }
                    else {
                      const float coef = (float)std::exp(-l*l/fsigma2);
                      cimg_forC(*this,c) val[c]+=(Tfloat)(coef*(*this)(cx,cy,0,c));
                      S+=coef;
                    }
                    X+=u; Y+=v;
                  }
                } break;
                case 1 : { // Linear interpolation
                  for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1; l+=dl) {
                    const float
                      u = (float)(W._linear_atXY(X,Y,0,0)),
                      v = (float)(W._linear_atXY(X,Y,0,1));
                    if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)_linear_atXY(X,Y,0,c); ++S; }
                    else {
                      const float coef = (float)std::exp(-l*l/fsigma2);
                      cimg_forC(*this,c) val[c]+=(Tfloat)(coef*_linear_atXY(X,Y,0,c));
                      S+=coef;
                    }
                    X+=u; Y+=v;
                  }
                } break;
                default : { // 2nd-order Runge-kutta interpolation
                  for (float l = 0; l<length && X>=0 && X<=dx1 && Y>=0 && Y<=dy1; l+=dl) {
                    const float
                      u0 = (float)(0.5f*W._linear_atXY(X,Y,0,0)),
                      v0 = (float)(0.5f*W._linear_atXY(X,Y,0,1)),
                      u = (float)(W._linear_atXY(X + u0,Y + v0,0,0)),
                      v = (float)(W._linear_atXY(X + u0,Y + v0,0,1));
                    if (is_fast_approx) { cimg_forC(*this,c) val[c]+=(Tfloat)_linear_atXY(X,Y,0,c); ++S; }
                    else {
                      const float coef = (float)std::exp(-l*l/fsigma2);
                      cimg_forC(*this,c) val[c]+=(Tfloat)(coef*_linear_atXY(X,Y,0,c));
                      S+=coef;
                    }
                    X+=u; Y+=v;
                  }
                }
                }
                Tfloat *ptrd = res.data(x,y);
                if (S>0) cimg_forC(res,c) { *ptrd+=val[c]/S; ptrd+=whd; }
                else cimg_forC(res,c) { *ptrd+=(Tfloat)((*this)(x,y,0,c)); ptrd+=whd; }
              }
            } _cimg_abort_catch_openmp2
          }
        }
        const Tfloat *ptrs = res._data;
        cimg_for(*this,ptrd,T) {
          const Tfloat _val = *(ptrs++)/N;
          *ptrd = _val<val_min?val_min:(_val>val_max?val_max:(T)_val);
        }
      }
      cimg_abort_test;
      return *this;
    }

    //! Blur image anisotropically, directed by a field of diffusion tensors \newinstance.
    template<typename t>
    CImg<Tfloat> get_blur_anisotropic(const CImg<t>& G,
                                      const float amplitude=60, const float dl=0.8f, const float da=30,
                                      const float gauss_prec=2, const unsigned int interpolation_type=0,
                                      const bool is_fast_approx=true) const {
      return CImg<Tfloat>(*this,false).blur_anisotropic(G,amplitude,dl,da,gauss_prec,interpolation_type,is_fast_approx);
    }

    //! Blur image anisotropically, in an edge-preserving way.
    /**
       \param amplitude Amplitude of the smoothing.
       \param sharpness Sharpness.
       \param anisotropy Anisotropy.
       \param alpha Standard deviation of the gradient blur.
       \param sigma Standard deviation of the structure tensor blur.
       \param dl Spatial discretization.
       \param da Angular discretization.
       \param gauss_prec Precision of the diffusion process.
       \param interpolation_type Interpolation scheme.
         Can be <tt>{ 0=nearest-neighbor | 1=linear | 2=Runge-Kutta }</tt>.
       \param is_fast_approx Indicates whether a fast approximation of the gaussian function is used.
     **/
    CImg<T>& blur_anisotropic(const float amplitude, const float sharpness=0.7f, const float anisotropy=0.6f,
                              const float alpha=0.6f, const float sigma=1.1f, const float dl=0.8f, const float da=30,
                              const float gauss_prec=2, const unsigned int interpolation_type=0,
                              const bool is_fast_approx=true) {
      const float nalpha = alpha>=0?alpha:-alpha*cimg::max(_width,_height,_depth)/100;
      const float nsigma = sigma>=0?sigma:-sigma*cimg::max(_width,_height,_depth)/100;
      return blur_anisotropic(get_diffusion_tensors(sharpness,anisotropy,nalpha,nsigma,interpolation_type!=3),
                              amplitude,dl,da,gauss_prec,interpolation_type,is_fast_approx);
    }

    //! Blur image anisotropically, in an edge-preserving way \newinstance.
    CImg<Tfloat> get_blur_anisotropic(const float amplitude, const float sharpness=0.7f, const float anisotropy=0.6f,
                                      const float alpha=0.6f, const float sigma=1.1f, const float dl=0.8f,
                                      const float da=30, const float gauss_prec=2,
                                      const unsigned int interpolation_type=0,
                                      const bool is_fast_approx=true) const {
      return CImg<Tfloat>(*this,false).blur_anisotropic(amplitude,sharpness,anisotropy,alpha,sigma,dl,da,gauss_prec,
                                                        interpolation_type,is_fast_approx);
    }

    //! Blur image, with the joint bilateral filter.
    /**
       \param guide Image used to model the smoothing weights.
       \param sigma_x Amount of blur along the X-axis.
       \param sigma_y Amount of blur along the Y-axis.
       \param sigma_z Amount of blur along the Z-axis.
       \param sigma_r Amount of blur along the value axis.
       \param sampling_x Amount of downsampling along the X-axis used for the approximation.
         Defaults (0) to sigma_x.
       \param sampling_y Amount of downsampling along the Y-axis used for the approximation.
         Defaults (0) to sigma_y.
       \param sampling_z Amount of downsampling along the Z-axis used for the approximation.
         Defaults (0) to sigma_z.
       \param sampling_r Amount of downsampling along the value axis used for the approximation.
         Defaults (0) to sigma_r.
       \note This algorithm uses the optimisation technique proposed by S. Paris and F. Durand, in ECCV'2006
       (extended for 3D volumetric images).
       It is based on the reference implementation http://people.csail.mit.edu/jiawen/software/bilateralFilter.m
    **/
    template<typename t>
    CImg<T>& blur_bilateral(const CImg<t>& guide,
                            const float sigma_x, const float sigma_y,
                            const float sigma_z, const float sigma_r,
                            const float sampling_x, const float sampling_y,
                            const float sampling_z, const float sampling_r) {
      if (!is_sameXYZ(guide))
        throw CImgArgumentException(_cimg_instance
                                    "blur_bilateral(): Invalid size for specified guide image (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    guide._width,guide._height,guide._depth,guide._spectrum,guide._data);
      if (is_empty() || (!sigma_x && !sigma_y && !sigma_z)) return *this;
      T edge_min, edge_max = guide.max_min(edge_min);
      if (edge_min==edge_max) return blur(sigma_x,sigma_y,sigma_z);
      const float
        edge_delta = (float)(edge_max - edge_min),
        _sigma_x = sigma_x>=0?sigma_x:-sigma_x*_width/100,
        _sigma_y = sigma_y>=0?sigma_y:-sigma_y*_height/100,
        _sigma_z = sigma_z>=0?sigma_z:-sigma_z*_depth/100,
        _sigma_r = sigma_r>=0?sigma_r:-sigma_r*edge_delta/100,
        _sampling_x = sampling_x?sampling_x:std::max(_sigma_x,1.f),
        _sampling_y = sampling_y?sampling_y:std::max(_sigma_y,1.f),
        _sampling_z = sampling_z?sampling_z:std::max(_sigma_z,1.f),
        _sampling_r = sampling_r?sampling_r:std::max(_sigma_r,edge_delta/256),
        derived_sigma_x = _sigma_x / _sampling_x,
        derived_sigma_y = _sigma_y / _sampling_y,
        derived_sigma_z = _sigma_z / _sampling_z,
        derived_sigma_r = _sigma_r / _sampling_r;
      const int
        padding_x = (int)(2*derived_sigma_x) + 1,
        padding_y = (int)(2*derived_sigma_y) + 1,
        padding_z = (int)(2*derived_sigma_z) + 1,
        padding_r = (int)(2*derived_sigma_r) + 1;
      const unsigned int
        bx = (unsigned int)((_width  - 1)/_sampling_x + 1 + 2*padding_x),
        by = (unsigned int)((_height - 1)/_sampling_y + 1 + 2*padding_y),
        bz = (unsigned int)((_depth  - 1)/_sampling_z + 1 + 2*padding_z),
        br = (unsigned int)(edge_delta/_sampling_r + 1 + 2*padding_r);
      if (bx>0 || by>0 || bz>0 || br>0) {
        const bool is_3d = (_depth>1);
        if (is_3d) { // 3D version of the algorithm
          CImg<floatT> bgrid(bx,by,bz,br), bgridw(bx,by,bz,br);
          cimg_forC(*this,c) {
            const CImg<t> _guide = guide.get_shared_channel(c%guide._spectrum);
            bgrid.fill(0); bgridw.fill(0);
            cimg_forXYZ(*this,x,y,z) {
              const T val = (*this)(x,y,z,c);
              const float edge = (float)_guide(x,y,z);
              const int
                X = (int)cimg::round(x/_sampling_x) + padding_x,
                Y = (int)cimg::round(y/_sampling_y) + padding_y,
                Z = (int)cimg::round(z/_sampling_z) + padding_z,
                R = (int)cimg::round((edge - edge_min)/_sampling_r) + padding_r;
              bgrid(X,Y,Z,R)+=(float)val;
              bgridw(X,Y,Z,R)+=1;
            }
            bgrid.blur(derived_sigma_x,derived_sigma_y,derived_sigma_z,true).deriche(derived_sigma_r,0,'c',false);
            bgridw.blur(derived_sigma_x,derived_sigma_y,derived_sigma_z,true).deriche(derived_sigma_r,0,'c',false);

            cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(size(),4096))
            cimg_forXYZ(*this,x,y,z) {
              const float edge = (float)_guide(x,y,z);
              const float
                X = x/_sampling_x + padding_x,
                Y = y/_sampling_y + padding_y,
                Z = z/_sampling_z + padding_z,
                R = (edge - edge_min)/_sampling_r + padding_r;
              const float bval0 = bgrid._linear_atXYZC(X,Y,Z,R), bval1 = bgridw._linear_atXYZC(X,Y,Z,R);
              (*this)(x,y,z,c) = (T)(bval0/bval1);
            }
          }
        } else { // 2D version of the algorithm
          CImg<floatT> bgrid(bx,by,br,2);
          cimg_forC(*this,c) {
            const CImg<t> _guide = guide.get_shared_channel(c%guide._spectrum);
            bgrid.fill(0);
            cimg_forXY(*this,x,y) {
              const T val = (*this)(x,y,c);
              const float edge = (float)_guide(x,y);
              const int
                X = (int)cimg::round(x/_sampling_x) + padding_x,
                Y = (int)cimg::round(y/_sampling_y) + padding_y,
                R = (int)cimg::round((edge - edge_min)/_sampling_r) + padding_r;
              bgrid(X,Y,R,0)+=(float)val;
              bgrid(X,Y,R,1)+=1;
            }
            bgrid.blur(derived_sigma_x,derived_sigma_y,0,true).blur(0,0,derived_sigma_r,false);

            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(size(),4096))
            cimg_forXY(*this,x,y) {
              const float edge = (float)_guide(x,y);
              const float
                X = x/_sampling_x + padding_x,
                Y = y/_sampling_y + padding_y,
                R = (edge - edge_min)/_sampling_r + padding_r;
              const float bval0 = bgrid._linear_atXYZ(X,Y,R,0), bval1 = bgrid._linear_atXYZ(X,Y,R,1);
              (*this)(x,y,c) = (T)(bval0/bval1);
            }
          }
        }
      }
      return *this;
    }

    //! Blur image, with the joint bilateral filter \newinstance.
    template<typename t>
    CImg<Tfloat> get_blur_bilateral(const CImg<t>& guide,
                                    const float sigma_x, const float sigma_y,
                                    const float sigma_z, const float sigma_r,
                                    const float sampling_x, const float sampling_y,
                                    const float sampling_z, const float sampling_r) const {
      return CImg<Tfloat>(*this,false).blur_bilateral(guide,sigma_x,sigma_y,sigma_z,sigma_r,
                                                      sampling_x,sampling_y,sampling_z,sampling_r);
    }

    //! Blur image using the joint bilateral filter.
    /**
       \param guide Image used to model the smoothing weights.
       \param sigma_s Amount of blur along the XYZ-axes.
       \param sigma_r Amount of blur along the value axis.
       \param sampling_s Amount of downsampling along the XYZ-axes used for the approximation. Defaults to sigma_s.
       \param sampling_r Amount of downsampling along the value axis used for the approximation. Defaults to sigma_r.
    **/
    template<typename t>
    CImg<T>& blur_bilateral(const CImg<t>& guide,
                            const float sigma_s, const float sigma_r,
                            const float sampling_s=0, const float sampling_r=0) {
      const float _sigma_s = sigma_s>=0?sigma_s:-sigma_s*cimg::max(_width,_height,_depth)/100;
      return blur_bilateral(guide,_sigma_s,_sigma_s,_sigma_s,sigma_r,sampling_s,sampling_s,sampling_s,sampling_r);
    }

    //! Blur image using the bilateral filter \newinstance.
    template<typename t>
    CImg<Tfloat> get_blur_bilateral(const CImg<t>& guide,
                                    const float sigma_s, const float sigma_r,
                                    const float sampling_s=0, const float sampling_r=0) const {
      return CImg<Tfloat>(*this,false).blur_bilateral(guide,sigma_s,sigma_r,sampling_s,sampling_r);
    }

    // [internal] Apply a box filter (used by CImg<T>::boxfilter() and CImg<T>::blur_box()).
    /*
      \param ptr the pointer of the data
      \param N size of the data
      \param boxsize Size of the box filter (can be subpixel).
      \param off the offset between two data point
      \param order the order of the filter 0 (smoothing), 1st derivative and 2nd derivative.
      \param boundary_conditions Boundary conditions.
        Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
    */
    static void _cimg_blur_box_apply(T *ptr, const float boxsize, const int N, const ulongT off,
                                     const int order, const unsigned int boundary_conditions,
                                     const unsigned int nb_iter) {
      const int nboundary_conditions = boundary_conditions>1 && boxsize<=3?1:boundary_conditions;

      // Smooth.
      if (boxsize>1 && nb_iter) {
        const int w2 = (int)(boxsize - 1)/2;
        const unsigned int winsize = 2*w2 + 1U;
        const double frac = (boxsize - winsize)/2.;
        CImg<T> win(winsize);
        for (unsigned int iter = 0; iter<nb_iter; ++iter) {
          Tdouble sum = 0; // window sum
          for (int x = -w2; x<=w2; ++x) {
            win[x + w2] = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,x);
            sum+=win[x + w2];
          }
          int ifirst = 0, ilast = 2*w2;
          T
            prev = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,-w2 - 1),
            next = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,w2 + 1);
          for (int x = 0; x < N - 1; ++x) {
            const double sum2 = sum + frac * (prev + next);
            ptr[x*off] = (T)(sum2/boxsize);
            prev = win[ifirst];
            sum-=prev;
            ifirst = (int)((ifirst + 1)%winsize);
            ilast = (int)((ilast + 1)%winsize);
            win[ilast] = next;
            sum+=next;
            next = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,x + w2 + 2);
          }
          const double sum2 = sum + frac * (prev + next);
          ptr[(N - 1)*off] = (T)(sum2/boxsize);
        }
      }

      // Derive.
      switch (order) {
      case 0 :
        break;
      case 1 : {
        Tfloat
          p = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,-1),
          c = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,0),
          n = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,1);
        for (int x = 0; x<N - 1; ++x) {
          ptr[x*off] = (T)((n-p)/2.);
          p = c;
          c = n;
          n = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,x + 2);
        }
        ptr[(N - 1)*off] = (T)((n-p)/2.);
      } break;
      case 2: {
        Tfloat
          p = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,-1),
          c = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,0),
          n = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,1);
        for (int x = 0; x<N - 1; ++x) {
          ptr[x*off] = (T)(n - 2*c + p);
          p = c;
          c = n;
          n = __cimg_blur_box_apply(ptr,N,off,nboundary_conditions,x + 2);
        }
        ptr[(N - 1)*off] = (T)(n - 2*c + p);
      } break;
      }
    }

    static T __cimg_blur_box_apply(T *ptr, const int N, const ulongT off,
                                   const unsigned int boundary_conditions, const int x) {
      switch (boundary_conditions) {
      case 0 : // Dirichlet
        return x<0 || x>=N?(T)0:ptr[x*off];
      case 1 : { // Neumann
        const int nx = x<0?0:x>=N?N - 1:x;
        return ptr[nx*off];
      }
      case 2 : { // Periodic
        const int nx = cimg::mod(x,N);
        return ptr[nx*off];
      }
      default : { // Mirror
        const int
          N2 = 2*N,
          tx = cimg::mod(x,N2),
          nx = tx<N?tx:N2 - tx - 1;
        return ptr[nx*off];
      }
      }
      return (T)0;
    }

    // Apply box filter of order 0,1,2.
    /**
      \param boxsize Size of the box window (can be subpixel)
      \param order the order of the filter 0,1 or 2.
      \param axis  Axis along which the filter is computed. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param boundary_conditions Boundary conditions.
        Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
      \param nb_iter Number of filter iterations.
    **/
    CImg<T>& boxfilter(const float boxsize, const int order, const char axis='x',
                       const unsigned int boundary_conditions=1,
                       const unsigned int nb_iter=1) {
      const char naxis = cimg::lowercase(axis);
      const float nboxsize = boxsize>=0?boxsize:-boxsize*
        (naxis=='x'?_width:naxis=='y'?_height:naxis=='z'?_depth:_spectrum)/100;
      if (is_empty() || !nboxsize || (nboxsize<=1 && !order)) return *this;
      switch (naxis) {
      case 'x' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forYZC(*this,y,z,c)
          _cimg_blur_box_apply(data(0,y,z,c),nboxsize,_width,1U,order,boundary_conditions,nb_iter);
      } break;
      case 'y' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXZC(*this,x,z,c)
          _cimg_blur_box_apply(data(x,0,z,c),nboxsize,_height,(ulongT)_width,order,boundary_conditions,nb_iter);
      } break;
      case 'z' : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYC(*this,x,y,c)
          _cimg_blur_box_apply(data(x,y,0,c),nboxsize,_depth,(ulongT)_width*_height,order,boundary_conditions,nb_iter);
      } break;
      default : {
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth*_spectrum>=16))
        cimg_forXYZ(*this,x,y,z)
          _cimg_blur_box_apply(data(x,y,z,0),nboxsize,_spectrum,(ulongT)_width*_height*_depth,
                               order,boundary_conditions,nb_iter);
      }
      }
      return *this;
    }

    // Apply box filter of order 0,1 or 2 \newinstance.
    CImg<Tfloat> get_boxfilter(const float boxsize, const int order, const char axis='x',
                               const unsigned int boundary_conditions=1,
                               const unsigned int nb_iter=1) const {
      return CImg<Tfloat>(*this,false).boxfilter(boxsize,order,axis,boundary_conditions,nb_iter);
    }

    //! Blur image with a box filter.
    /**
       \param boxsize_x Size of the box window, along the X-axis (can be subpixel).
       \param boxsize_y Size of the box window, along the Y-axis (can be subpixel).
       \param boxsize_z Size of the box window, along the Z-axis (can be subpixel).
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ false=dirichlet | true=neumann | 2=periodic | 3=mirror }</tt>.
       \param nb_iter Number of filter iterations.
       \note
       - This is a recursive algorithm, not depending on the values of the box kernel size.
       \see blur().
    **/
    CImg<T>& blur_box(const float boxsize_x, const float boxsize_y, const float boxsize_z,
                      const unsigned int boundary_conditions=1,
                      const unsigned int nb_iter=1) {
      if (is_empty()) return *this;
      if (_width>1) boxfilter(boxsize_x,0,'x',boundary_conditions,nb_iter);
      if (_height>1) boxfilter(boxsize_y,0,'y',boundary_conditions,nb_iter);
      if (_depth>1) boxfilter(boxsize_z,0,'z',boundary_conditions,nb_iter);
      return *this;
    }

    //! Blur image with a box filter \newinstance.
    CImg<Tfloat> get_blur_box(const float boxsize_x, const float boxsize_y, const float boxsize_z,
                              const unsigned int boundary_conditions=1) const {
      return CImg<Tfloat>(*this,false).blur_box(boxsize_x,boxsize_y,boxsize_z,boundary_conditions);
    }

    //! Blur image with a box filter.
    /**
       \param boxsize Size of the box window (can be subpixel).
       \param boundary_conditions Boundary conditions.
         Can be <tt>{ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }</tt>.
       \see deriche(), vanvliet().
    **/
    CImg<T>& blur_box(const float boxsize, const unsigned int boundary_conditions=1) {
      const float nboxsize = boxsize>=0?boxsize:-boxsize*cimg::max(_width,_height,_depth)/100;
      return blur_box(nboxsize,nboxsize,nboxsize,boundary_conditions);
    }

    //! Blur image with a box filter \newinstance.
    CImg<Tfloat> get_blur_box(const float boxsize, const unsigned int boundary_conditions=1) const {
      return CImg<Tfloat>(*this,false).blur_box(boxsize,boundary_conditions);
    }

    //! Blur image, with the image guided filter.
    /**
       \param guide Image used to guide the smoothing process.
       \param radius Spatial radius. If negative, it is expressed as a percentage of the largest image size.
       \param regularization Regularization parameter.
                             If negative, it is expressed as a percentage of the guide value range.
       \note This function implements the filtering algorithm described in:
       He, Kaiming; Sun, Jian; Tang, Xiaoou, "Guided Image Filtering," Pattern Analysis and Machine Intelligence,
       IEEE Transactions on , vol.35, no.6, pp.1397,1409, June 2013
    **/
    template<typename t>
    CImg<T>& blur_guided(const CImg<t>& guide, const float radius, const float regularization) {
      return get_blur_guided(guide,radius,regularization).move_to(*this);
    }

    //! Blur image, with the image guided filter \newinstance.
    template<typename t>
    CImg<Tfloat> get_blur_guided(const CImg<t>& guide, const float radius, const float regularization) const {
      if (!is_sameXYZ(guide))
        throw CImgArgumentException(_cimg_instance
                                    "blur_guided(): Invalid size for specified guide image (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    guide._width,guide._height,guide._depth,guide._spectrum,guide._data);
      if (is_empty() || !radius) return *this;
      const int _radius = radius>=0?(int)radius:(int)(-radius*cimg::max(_width,_height,_depth)/100);
      float _regularization = regularization;
      if (regularization<0) {
        T edge_min, edge_max = guide.max_min(edge_min);
        if (edge_min==edge_max) return *this;
        _regularization = -regularization*(edge_max - edge_min)/100;
      }
      _regularization = std::max(_regularization,0.01f);
      const unsigned int psize = (unsigned int)(1 + 2*_radius);
      CImg<Tfloat>
        mean_p = get_blur_box(psize,true),
        mean_I = guide.get_blur_box(psize,true).resize(mean_p),
        cov_Ip = get_mul(guide).blur_box(psize,true)-=mean_p.get_mul(mean_I),
        var_I = guide.get_sqr().blur_box(psize,true)-=mean_I.get_sqr(),
        &a = cov_Ip.div(var_I+=_regularization),
        &b = mean_p-=a.get_mul(mean_I);
      a.blur_box(psize,true);
      b.blur_box(psize,true);
      return a.mul(guide)+=b;
    }

    //! Blur image using patch-based space.
    /**
       \param guide Image used to model the smoothing weights.
       \param sigma_s Amount of blur along the XYZ-axes.
       \param sigma_r Amount of blur along the value axis.
       \param patch_size Size of the patches.
       \param lookup_size Size of the window to search similar patches.
       \param smoothness Smoothness for the patch comparison.
       \param is_fast_approx Indicates whether a fast approximation of the gaussian function is used.
    **/
    template<typename t>
    CImg<T>& blur_patch(const CImg<t>& guide,
                        const float sigma_s, const float sigma_r, const unsigned int patch_size=3,
                        const unsigned int lookup_size=4, const float smoothness=0, const bool is_fast_approx=true) {
      if (is_empty() || !patch_size || !lookup_size) return *this;
      return get_blur_patch(guide,sigma_s,sigma_r,patch_size,lookup_size,smoothness,is_fast_approx).move_to(*this);
    }

    //! Blur image using patch-based space \newinstance.
    template<typename t>
    CImg<Tfloat> get_blur_patch(const CImg<t>& guide,
                                const float sigma_s, const float sigma_r, const unsigned int patch_size=3,
                                const unsigned int lookup_size=4, const float smoothness=0,
                                const bool is_fast_approx=true) const {

#define _cimg_blur_patch3d_fast(N) { \
      cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) \
                         cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height*res._depth>=4) \
                         firstprivate(P,Q)) \
      cimg_forXYZ(res,x,y,z) _cimg_abort_try_openmp2 { \
        cimg_abort_test2; \
        cimg_def##N##x##N##x##N(res,x,y,z); \
        tfloat *pP = P._data; cimg_forC(_guide,c) { cimg_get##N##x##N##x##N(_guide,x,y,z,c,pP,tfloat); pP+=N3; } \
        const int x0 = x - rsize1, y0 = y - rsize1, z0 = z - rsize1, \
                  x1 = x + rsize2, y1 = y + rsize2, z1 = z + rsize2; \
        tfloat sum_weights = 0; \
        cimg_for_in##N##XYZ(res,x0,y0,z0,x1,y1,z1,p,q,r) \
          if (cimg::abs(_guide(x,y,z,0) - _guide(p,q,r,0))<sigma_r3) { \
            tfloat *pQ = Q._data; cimg_forC(_guide,c) { cimg_get##N##x##N##x##N(_guide,p,q,r,c,pQ,tfloat); pQ+=N3; } \
            tfloat distance2 = 0; \
            pQ = Q._data; cimg_for(P,_pP,tfloat) { const tfloat dI = *_pP - *(pQ++); distance2+=dI*dI; } \
            distance2/=Pnorm; \
            const tfloat dx = (tfloat)p - x, dy = (tfloat)q - y, dz = (tfloat)r - z, \
              alldist = distance2 + (dx*dx + dy*dy + dz*dz)/sigma_s2, weight = alldist>3?0:1; \
            sum_weights+=weight; \
            cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight*(*this)(p,q,r,c); \
          } \
        if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,z,c)/=(Tfloat)sum_weights; \
        else cimg_forC(res,c) res(x,y,z,c) = (Tfloat)((*this)(x,y,z,c)); \
    } _cimg_abort_catch_openmp2 }

#define _cimg_blur_patch3d(N) { \
      cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) \
                         cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height*res._depth>=4) \
                         firstprivate(P,Q)) \
      cimg_forXYZ(res,x,y,z) _cimg_abort_try_openmp2 { \
        cimg_abort_test2; \
        cimg_def##N##x##N##x##N(res,x,y,z); \
        tfloat *pP = P._data; cimg_forC(_guide,c) { cimg_get##N##x##N##x##N(_guide,x,y,z,c,pP,tfloat); pP+=N3; } \
        const int x0 = x - rsize1, y0 = y - rsize1, z0 = z - rsize1, \
                  x1 = x + rsize2, y1 = y + rsize2, z1 = z + rsize2; \
        tfloat sum_weights = 0, weight_max = 0; \
        cimg_for_in##N##XYZ(res,x0,y0,z0,x1,y1,z1,p,q,r) if (p!=x || q!=y || r!=z) { \
          tfloat *pQ = Q._data; cimg_forC(_guide,c) { cimg_get##N##x##N##x##N(_guide,p,q,r,c,pQ,tfloat); pQ+=N3; } \
          tfloat distance2 = 0; \
          pQ = Q._data; cimg_for(P,_pP,tfloat) { const tfloat dI = *_pP - *(pQ++); distance2+=dI*dI; } \
          distance2/=Pnorm; \
          const tfloat dx = (tfloat)p - x, dy = (tfloat)q - y, dz = (tfloat)r - z, \
            alldist = distance2 + (dx*dx + dy*dy + dz*dz)/sigma_s2, weight = std::exp(-alldist); \
          if (weight>weight_max) weight_max = weight; \
          sum_weights+=weight; \
          cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight*(*this)(p,q,r,c); \
        } \
        sum_weights+=weight_max; cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight_max*(*this)(x,y,z,c); \
        if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,z,c)/=(Tfloat)sum_weights; \
        else cimg_forC(res,c) res(x,y,z,c) = (Tfloat)((*this)(x,y,z,c)); \
      } _cimg_abort_catch_openmp2 }

#define _cimg_blur_patch2d_fast(N) { \
        cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height>=4) \
                           firstprivate(P,Q)) \
        cimg_forXY(res,x,y) _cimg_abort_try_openmp2 { \
          cimg_abort_test2; \
          cimg_def##N##x##N(res,x,y); \
          tfloat *pP = P._data; cimg_forC(_guide,c) { cimg_get##N##x##N(_guide,x,y,0,c,pP,tfloat); pP+=N2; } \
          const int x0 = x - rsize1, y0 = y - rsize1, x1 = x + rsize2, y1 = y + rsize2; \
          tfloat sum_weights = 0; \
          cimg_for_in##N##XY(res,x0,y0,x1,y1,p,q) \
            if (cimg::abs(_guide(x,y,0,0) - _guide(p,q,0,0))<sigma_r3) { \
              tfloat *pQ = Q._data; cimg_forC(_guide,c) { cimg_get##N##x##N(_guide,p,q,0,c,pQ,tfloat); pQ+=N2; } \
              tfloat distance2 = 0; \
              pQ = Q._data; cimg_for(P,_pP,tfloat) { const tfloat dI = *_pP - *(pQ++); distance2+=dI*dI; } \
              distance2/=Pnorm; \
              const tfloat dx = (tfloat)p - x, dy = (tfloat)q - y, \
                alldist = distance2 + (dx*dx+dy*dy)/sigma_s2, weight = alldist>3?0:1; \
              sum_weights+=weight; \
              cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight*(*this)(p,q,c); \
            } \
          if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,c)/=(Tfloat)sum_weights; \
          else cimg_forC(res,c) res(x,y,c) = (Tfloat)((*this)(x,y,c)); \
        } _cimg_abort_catch_openmp2 }

#define _cimg_blur_patch2d(N) { \
        cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height>=4) \
                           firstprivate(P,Q)) \
        cimg_forXY(res,x,y) _cimg_abort_try_openmp2 { \
          cimg_abort_test2; \
          cimg_def##N##x##N(res,x,y); \
          tfloat *pP = P._data; cimg_forC(_guide,c) { cimg_get##N##x##N(_guide,x,y,0,c,pP,tfloat); pP+=N2; } \
          const int x0 = x - rsize1, y0 = y - rsize1, x1 = x + rsize2, y1 = y + rsize2; \
          tfloat sum_weights = 0, weight_max = 0; \
          cimg_for_in##N##XY(res,x0,y0,x1,y1,p,q) if (p!=x || q!=y) { \
            tfloat *pQ = Q._data; cimg_forC(_guide,c) { cimg_get##N##x##N(_guide,p,q,0,c,pQ,tfloat); pQ+=N2; } \
            tfloat distance2 = 0; \
            pQ = Q._data; cimg_for(P,_pP,tfloat) { const tfloat dI = *_pP - *(pQ++); distance2+=dI*dI; } \
            distance2/=Pnorm; \
            const tfloat dx = (tfloat)p - x, dy = (tfloat)q - y, \
              alldist = distance2 + (dx*dx+dy*dy)/sigma_s2, weight = std::exp(-alldist); \
            if (weight>weight_max) weight_max = weight; \
            sum_weights+=weight; \
            cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight*(*this)(p,q,c); \
          } \
          sum_weights+=weight_max; cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight_max*(*this)(x,y,c); \
          if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,c)/=(Tfloat)sum_weights; \
          else cimg_forC(res,c) res(x,y,c) = (Tfloat)((*this)(x,y,c)); \
    } _cimg_abort_catch_openmp2 }

      typedef _cimg_tfloat tfloat;
      if (!is_sameXYZ(guide))
        throw CImgArgumentException(_cimg_instance
                                    "blur_patch(): Invalid size for specified guide image (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    guide._width,guide._height,guide._depth,guide._spectrum,guide._data);
      if (is_empty() || !patch_size || !lookup_size) return +*this;
      Tfloat val_min, val_max = (Tfloat)max_min(val_min);
      _cimg_abort_init_openmp;
      cimg_abort_init;

      CImg<Tfloat> res(_width,_height,_depth,_spectrum,0);
      const CImg<tfloat>
        __guide = guide?CImg<tfloat>(guide,guide.pixel_type()==cimg::type<tfloat>::string()):
                        CImg<tfloat>(*this,pixel_type()==cimg::type<tfloat>::string()),
        _guide = smoothness>0?__guide.get_blur(smoothness):__guide.get_shared();
      CImg<tfloat> P(_guide._spectrum*patch_size*patch_size*(_depth>1?patch_size:1)), Q(P);

      t guide_min = (t)0, guide_max = (t)0;
      if (sigma_r<0) guide_max = guide.max_min(guide_min);
      const float
        guide_delta = (float)(guide_max - guide_min),
        _sigma_s = sigma_s>=0?sigma_s:-sigma_s*cimg::max(_width,_height,_depth)/100,
        _sigma_r = sigma_r>=0?sigma_r:-sigma_r*guide_delta/100,
        sigma_s2 = _sigma_s*_sigma_s,
        sigma_r2 = _sigma_r*_sigma_r,
        sigma_r3 = 3*_sigma_r,
        Pnorm = P.size()*sigma_r2;
      const int rsize2 = (int)lookup_size/2, rsize1 = (int)lookup_size - rsize2 - 1;
      const unsigned int N2 = patch_size*patch_size, N3 = N2*patch_size;
      cimg::unused(N2,N3);
      if (_depth>1) switch (patch_size) { // 3D
        case 2 : if (is_fast_approx) _cimg_blur_patch3d_fast(2) else _cimg_blur_patch3d(2) break;
        case 3 : if (is_fast_approx) _cimg_blur_patch3d_fast(3) else _cimg_blur_patch3d(3) break;
        default : {
          const int psize2 = (int)patch_size/2, psize1 = (int)patch_size - psize2 - 1;
          if (is_fast_approx) {
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height*res._depth>=4)
                               firstprivate(P,Q))
            cimg_forXYZ(res,x,y,z) _cimg_abort_try_openmp2 { // Fast
              cimg_abort_test2;
              P = _guide.get_crop(x - psize1,y - psize1,z - psize1,x + psize2,y + psize2,z + psize2,true);
              const int x0 = x - rsize1, y0 = y - rsize1, z0 = z - rsize1,
                x1 = x + rsize2, y1 = y + rsize2, z1 = z + rsize2;
              tfloat sum_weights = 0;
              cimg_for_inXYZ(res,x0,y0,z0,x1,y1,z1,p,q,r)
                if (cimg::abs(_guide(x,y,z,0) - _guide(p,q,r,0))<sigma_r3) {
                  (Q = _guide.get_crop(p - psize1,q - psize1,r - psize1,p + psize2,q + psize2,r + psize2,true))-=P;
                  const tfloat
                    dx = (tfloat)x - p, dy = (tfloat)y - q, dz = (tfloat)z - r,
                    distance2 = (tfloat)(Q.pow(2).sum()/Pnorm + (dx*dx + dy*dy + dz*dz)/sigma_s2),
                    weight = distance2>3?0:1;
                  sum_weights+=weight;
                  cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight*(*this)(p,q,r,c);
                }
              if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,z,c)/=(Tfloat)sum_weights;
              else cimg_forC(res,c) res(x,y,z,c) = (Tfloat)((*this)(x,y,z,c));
            } _cimg_abort_catch_openmp2
          } else {
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height*res._depth>=4)
                               firstprivate(P,Q))
            cimg_forXYZ(res,x,y,z) _cimg_abort_try_openmp2 { // Exact
              cimg_abort_test2;
              P = _guide.get_crop(x - psize1,y - psize1,z - psize1,x + psize2,y + psize2,z + psize2,true);
              const int x0 = x - rsize1, y0 = y - rsize1, z0 = z - rsize1,
                        x1 = x + rsize2, y1 = y + rsize2, z1 = z + rsize2;
              tfloat sum_weights = 0, weight_max = 0;
              cimg_for_inXYZ(res,x0,y0,z0,x1,y1,z1,p,q,r) if (p!=x || q!=y || r!=z) {
                (Q = _guide.get_crop(p - psize1,q - psize1,r - psize1,p + psize2,q + psize2,r + psize2,true))-=P;
                const tfloat
                  dx = (tfloat)x - p, dy = (tfloat)y - q, dz = (tfloat)z - r,
                  distance2 = (tfloat)(Q.pow(2).sum()/Pnorm + (dx*dx + dy*dy + dz*dz)/sigma_s2),
                  weight = std::exp(-distance2);
                if (weight>weight_max) weight_max = weight;
                sum_weights+=weight;
                cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight*(*this)(p,q,r,c);
              }
              sum_weights+=weight_max; cimg_forC(res,c) res(x,y,z,c)+=(Tfloat)weight_max*(*this)(x,y,z,c);
              if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,z,c)/=(Tfloat)sum_weights;
              else cimg_forC(res,c) res(x,y,z,c) = (Tfloat)((*this)(x,y,z,c));
            } _cimg_abort_catch_openmp2
          }
        }
        } else switch (patch_size) { // 2D
        case 2 : if (is_fast_approx) _cimg_blur_patch2d_fast(2) else _cimg_blur_patch2d(2) break;
        case 3 : if (is_fast_approx) _cimg_blur_patch2d_fast(3) else _cimg_blur_patch2d(3) break;
        case 4 : if (is_fast_approx) _cimg_blur_patch2d_fast(4) else _cimg_blur_patch2d(4) break;
        case 5 : if (is_fast_approx) _cimg_blur_patch2d_fast(5) else _cimg_blur_patch2d(5) break;
        case 6 : if (is_fast_approx) _cimg_blur_patch2d_fast(6) else _cimg_blur_patch2d(6) break;
        case 7 : if (is_fast_approx) _cimg_blur_patch2d_fast(7) else _cimg_blur_patch2d(7) break;
        case 8 : if (is_fast_approx) _cimg_blur_patch2d_fast(8) else _cimg_blur_patch2d(8) break;
        case 9 : if (is_fast_approx) _cimg_blur_patch2d_fast(9) else _cimg_blur_patch2d(9) break;
        default : { // Fast
          const int psize2 = (int)patch_size/2, psize1 = (int)patch_size - psize2 - 1;
          if (is_fast_approx) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height>=4)
                               firstprivate(P,Q))
            cimg_forXY(res,x,y) _cimg_abort_try_openmp2 { // Fast
              cimg_abort_test2;
              P = _guide.get_crop(x - psize1,y - psize1,x + psize2,y + psize2,true);
              const int x0 = x - rsize1, y0 = y - rsize1, x1 = x + rsize2, y1 = y + rsize2;
              tfloat sum_weights = 0;
              cimg_for_inXY(res,x0,y0,x1,y1,p,q)
                if (cimg::abs(_guide(x,y,0) - _guide(p,q,0))<sigma_r3) {
                  (Q = _guide.get_crop(p - psize1,q - psize1,p + psize2,q + psize2,true))-=P;
                  const tfloat
                    dx = (tfloat)x - p, dy = (tfloat)y - q,
                    distance2 = (tfloat)(Q.pow(2).sum()/Pnorm + (dx*dx + dy*dy)/sigma_s2),
                    weight = distance2>3?0:1;
                  sum_weights+=weight;
                  cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight*(*this)(p,q,c);
                }
              if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,c)/=(Tfloat)sum_weights;
              else cimg_forC(res,c) res(x,y,c) = (Tfloat)((*this)(x,y,c));
            } _cimg_abort_catch_openmp2
          } else {
            cimg_pragma_openmp(parallel for cimg_openmp_if(res._width>=(cimg_openmp_sizefactor)*32 && res._height>=4)
                               firstprivate(P,Q))
            cimg_forXY(res,x,y) _cimg_abort_try_openmp2 { // Exact
              cimg_abort_test2;
              P = _guide.get_crop(x - psize1,y - psize1,x + psize2,y + psize2,true);
              const int x0 = x - rsize1, y0 = y - rsize1, x1 = x + rsize2, y1 = y + rsize2;
              tfloat sum_weights = 0, weight_max = 0;
              cimg_for_inXY(res,x0,y0,x1,y1,p,q) if (p!=x || q!=y) {
                (Q = _guide.get_crop(p - psize1,q - psize1,p + psize2,q + psize2,true))-=P;
                const tfloat
                  dx = (tfloat)x - p, dy = (tfloat)y - q,
                  distance2 = (tfloat)(Q.pow(2).sum()/Pnorm + (dx*dx + dy*dy)/sigma_s2),
                  weight = std::exp(-distance2);
                if (weight>weight_max) weight_max = weight;
                sum_weights+=weight;
                cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight*(*this)(p,q,c);
              }
              sum_weights+=weight_max; cimg_forC(res,c) res(x,y,c)+=(Tfloat)weight_max*(*this)(x,y,c);
              if (sum_weights>1e-10) cimg_forC(res,c) res(x,y,c)/=(Tfloat)sum_weights;
              else cimg_forC(res,c) res(x,y,c) = (Tfloat)((*this)(x,y,c));
            } _cimg_abort_catch_openmp2
          }
        }
        }
      cimg_abort_test;
      return res.cut(val_min,val_max);
    }

    //! Blur image using patch-based space \overload.
    CImg<T>& blur_patch(const float sigma_s, const float sigma_r, const unsigned int patch_size=3,
                        const unsigned int lookup_size=4, const float smoothness=0, const bool is_fast_approx=true) {
      return blur_patch(*this,sigma_s,sigma_r,patch_size,lookup_size,smoothness,is_fast_approx);
    }

    //! Blur image using patch-based space \overload \newinstance.
    CImg<Tfloat> get_blur_patch(const float sigma_s, const float sigma_r, const unsigned int patch_size=3,
                                const unsigned int lookup_size=4, const float smoothness=0,
                                const bool is_fast_approx=true) const {
      return get_blur_patch(*this,sigma_s,sigma_r,patch_size,lookup_size,smoothness,is_fast_approx);
    }

    //! Blur image with the median filter.
    /**
       \param n Size of the median filter.
       \param threshold Threshold used to discard pixels too far from the current pixel value in the median computation.
    **/
    CImg<T>& blur_median(const unsigned int n, const float threshold=0) {
      if (!n) return *this;
      return get_blur_median(n,threshold).move_to(*this);
    }

    //! Blur image with the median filter \newinstance.
    CImg<T> get_blur_median(const unsigned int n, const float threshold=0) const {
      if (is_empty() || n<=1) return +*this;

      // Manage special case of single-axis image.
      CImg<T> img = get_shared();
      const unsigned int whd = _width*_height*_depth;
      if (_width==whd || _height==whd || _depth==whd) { img._width = whd; img._height = img._depth = 1; }

      CImg<T> res(_width,_height,_depth,_spectrum);
      T *ptrd = res._data;
      cimg::unused(ptrd);
      const int hr = (int)n/2, hl = n - hr - 1;
      if (img._depth!=1) { // 3D
        if (threshold>0) // With threshold
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                             cimg_openmp_if(img._width>=(cimg_openmp_sizefactor)*16 &&
                                            img._height*img._depth*img._spectrum>=4))
          cimg_forXYZC(img,x,y,z,c) {
            const int
              x0 = x - hl, y0 = y - hl, z0 = z - hl, x1 = x + hr, y1 = y + hr, z1 = z + hr,
              nx0 = x0<0?0:x0, ny0 = y0<0?0:y0, nz0 = z0<0?0:z0,
              nx1 = x1>=img.width()?img.width() - 1:x1,
              ny1 = y1>=img.height()?img.height() - 1:y1,
              nz1 = z1>=img.depth()?img.depth() - 1:z1;
            const Tfloat val0 = (Tfloat)img(x,y,z,c);
            CImg<T> values(n*n*n);
            unsigned int nb_values = 0;
            T *_ptrd = values.data();
            cimg_for_inXYZ(img,nx0,ny0,nz0,nx1,ny1,nz1,p,q,r)
              if (cimg::abs(img(p,q,r,c) - val0)<=threshold) { *(_ptrd++) = img(p,q,r,c); ++nb_values; }
            res(x,y,z,c) = nb_values?values.get_shared_points(0,nb_values - 1).median():img(x,y,z,c);
          }
        else // Without threshold
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                             cimg_openmp_if(img._width>=(cimg_openmp_sizefactor)*16 &&
                                            img._height*img._depth*img._spectrum>=4))
          cimg_forXYZC(img,x,y,z,c) {
            const int
              x0 = x - hl, y0 = y - hl, z0 = z - hl, x1 = x + hr, y1 = y + hr, z1 = z + hr,
              nx0 = x0<0?0:x0, ny0 = y0<0?0:y0, nz0 = z0<0?0:z0,
              nx1 = x1>=img.width()?img.width() - 1:x1,
              ny1 = y1>=img.height()?img.height() - 1:y1,
              nz1 = z1>=img.depth()?img.depth() - 1:z1;
            res(x,y,z,c) = img.get_crop(nx0,ny0,nz0,c,nx1,ny1,nz1,c).median();
          }
      } else { // 2D or 1D
        if (threshold>0) // With threshold
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                             cimg_openmp_if(img._width>=(cimg_openmp_sizefactor)*16 &&
                                            img._height*img._spectrum>=4))
          cimg_forXYC(img,x,y,c) {
            const int
              x0 = x - hl, y0 = y - hl, x1 = x + hr, y1 = y + hr,
              nx0 = x0<0?0:x0, ny0 = y0<0?0:y0,
              nx1 = x1>=img.width()?img.width() - 1:x1,
              ny1 = y1>=img.height()?img.height() - 1:y1;
            const Tfloat val0 = (Tfloat)img(x,y,c);
            CImg<T> values(n*n);
            unsigned int nb_values = 0;
            T *_ptrd = values.data();
            cimg_for_inXY(img,nx0,ny0,nx1,ny1,p,q)
              if (cimg::abs(img(p,q,c) - val0)<=threshold) { *(_ptrd++) = img(p,q,c); ++nb_values; }
            res(x,y,c) = nb_values?values.get_shared_points(0,nb_values - 1).median():img(x,y,c);
          }
        else { // Without threshold
          const int
            w1 = img.width() - 1, h1 = img.height() - 1,
            w2 = img.width() - 2, h2 = img.height() - 2,
            w3 = img.width() - 3, h3 = img.height() - 3,
            w4 = img.width() - 4, h4 = img.height() - 4;

          if (n==3 && img._width>=2 && img._height==1) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(img._spectrum>=2))
            cimg_forC(img,c) {
              const T *_ptrs = img.data(0,0,0,c);
              T *_ptrd = res.data(0,0,0,c);
              cimg_for_in3(img._width,1,w2,x)
                _ptrd[x] = cimg::median(_ptrs[_p1x],_ptrs[x],_ptrs[_n1x]);
              _ptrd[0] = cimg::median(_ptrs[0],_ptrs[1]);
              _ptrd[w1] = cimg::median(_ptrs[w2],_ptrs[w1]);
            }
          } else if (n==5 && img._width>=4 && img._height==1) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(img._spectrum>=2))
            cimg_forC(img,c) {
              const T *_ptrs = img.data(0,0,0,c);
              T *_ptrd = res.data(0,0,0,c);
              cimg_for_in5(img._width,2,w3,x)
                _ptrd[x] = cimg::median(_ptrs[_p2x],_ptrs[_p1x],_ptrs[x],_ptrs[_n1x],_ptrs[_n2x]);
              _ptrd[0] = cimg::median(_ptrs[0],_ptrs[1],_ptrs[2]);
              _ptrd[1] = cimg::median(_ptrs[0],_ptrs[1],_ptrs[2],_ptrs[3]);
              _ptrd[w2] = cimg::median(_ptrs[w4],_ptrs[w3],_ptrs[w2],_ptrs[w1]);
              _ptrd[w1] = cimg::median(_ptrs[w3],_ptrs[w2],_ptrs[w1]);
            }
          } else if (n==3 && img._width>=n && img._height>=n) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(img._spectrum>=2))
            cimg_forC(img,c) {
              CImg<T> I(9);
              cimg_for_in3x3(img,1,1,w2,h2,x,y,0,c,I,T)
                res(x,y,c) = cimg::median(I[0],I[1],I[2],I[3],I[4],I[5],I[6],I[7],I[8]);
              cimg_for_borderXY(img,x,y,1)
                res(x,y,c) = img.get_crop(std::max(0,x - 1),std::max(0,y - 1),0,c,
                                          std::min(w1,x + 1),std::min(h1,y + 1),0,c).median();
            }
          } else if (n==5 && img._width>=n && img._height>=n) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(img._spectrum>=2))
            cimg_forC(img,c) {
              CImg<T> I(25);
              cimg_for_in5x5(img,2,2,w3,h3,x,y,0,c,I,T)
                res(x,y,c) = cimg::median(I[0],I[1],I[2],I[3],I[4],
                                          I[5],I[6],I[7],I[8],I[9],
                                          I[10],I[11],I[12],I[13],I[14],
                                          I[15],I[16],I[17],I[18],I[19],
                                          I[20],I[21],I[22],I[23],I[24]);
              cimg_for_borderXY(img,x,y,2)
                res(x,y,c) = img.get_crop(std::max(0,x - 2),std::max(0,y - 2),0,c,
                                          std::min(w1,x + 2),std::min(h1,y + 2),0,c).median();
            }
          } else if (n==7 && img._width>=n && img._height>=n) {
            cimg_pragma_openmp(parallel for cimg_openmp_if(img._spectrum>=2))
            cimg_forC(img,c) {
              CImg<T> I(49);
              cimg_for_in7x7(img,3,3,w4,h4,x,y,0,c,I,T)
                res(x,y,c) = cimg::median(I[0],I[1],I[2],I[3],I[4],I[5],I[6],
                                          I[7],I[8],I[9],I[10],I[11],I[12],I[13],
                                          I[14],I[15],I[16],I[17],I[18],I[19],I[20],
                                          I[21],I[22],I[23],I[24],I[25],I[26],I[27],
                                          I[28],I[29],I[30],I[31],I[32],I[33],I[34],
                                          I[35],I[36],I[37],I[38],I[39],I[40],I[41],
                                          I[42],I[43],I[44],I[45],I[46],I[47],I[48]);
              cimg_for_borderXY(img,x,y,3)
                res(x,y,c) = img.get_crop(std::max(0,x - 3),std::max(0,y - 3),0,c,
                                          std::min(w1,x + 3),std::min(h1,y + 3),0,c).median();
            }
          } else {
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(img._width>=(cimg_openmp_sizefactor)*16 &&
                                              img._height*img._spectrum>=4))
            cimg_forXYC(img,x,y,c) {
              const int
                x0 = x - hl, y0 = y - hl, x1 = x + hr, y1 = y + hr,
                nx0 = x0<0?0:x0, ny0 = y0<0?0:y0,
                nx1 = x1>=img.width()?img.width() - 1:x1,
                ny1 = y1>=img.height()?img.height() - 1:y1;
              res(x,y,c) = img.get_crop(nx0,ny0,0,c,nx1,ny1,0,c).median();
            }
          }
        }
      }
      return res;
    }

    //! Sharpen image.
    /**
       \param amplitude Sharpening amplitude
       \param sharpen_type Select sharpening method. Can be <tt>{ false=inverse diffusion | true=shock filters }</tt>.
       \param edge Edge threshold (shock filters only).
       \param alpha Gradient smoothness (shock filters only).
       \param sigma Tensor smoothness (shock filters only).
    **/
    CImg<T>& sharpen(const float amplitude, const bool sharpen_type=false, const float edge=1,
                     const float alpha=0, const float sigma=0) {
      if (is_empty()) return *this;
      T val_min, val_max = max_min(val_min);
      const float nedge = edge/2;
      CImg<Tfloat> velocity(_width,_height,_depth,_spectrum), _veloc_max(_spectrum);

      if (_depth>1) { // 3D
        if (sharpen_type) { // Shock filters
          CImg<Tfloat> G = (alpha>0?get_blur(alpha).get_structure_tensors():get_structure_tensors());
          if (sigma>0) G.blur(sigma);
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*32 &&
                                                                     _height*_depth>=16))
          cimg_forYZ(G,y,z) {
            Tfloat *ptrG0 = G.data(0,y,z,0), *ptrG1 = G.data(0,y,z,1),
              *ptrG2 = G.data(0,y,z,2), *ptrG3 = G.data(0,y,z,3);
            CImg<Tfloat> val, vec;
            cimg_forX(G,x) {
              G.get_tensor_at(x,y,z).symmetric_eigen(val,vec);
              if (val[0]<0) val[0] = 0;
              if (val[1]<0) val[1] = 0;
              if (val[2]<0) val[2] = 0;
              *(ptrG0++) = vec(0,0);
              *(ptrG1++) = vec(0,1);
              *(ptrG2++) = vec(0,2);
              *(ptrG3++) = 1 - (Tfloat)std::pow(1 + val[0] + val[1] + val[2],-(Tfloat)nedge);
            }
          }
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*512 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            Tfloat *ptrd = velocity.data(0,0,0,c), veloc_max = 0;
            CImg_3x3x3(I,Tfloat);
            cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) {
              const Tfloat
                u = G(x,y,z,0),
                v = G(x,y,z,1),
                w = G(x,y,z,2),
                amp = G(x,y,z,3),
                ixx = Incc + Ipcc - 2*Iccc,
                ixy = (Innc + Ippc - Inpc - Ipnc)/4,
                ixz = (Incn + Ipcp - Incp - Ipcn)/4,
                iyy = Icnc + Icpc - 2*Iccc,
                iyz = (Icnn + Icpp - Icnp - Icpn)/4,
                izz = Iccn + Iccp - 2*Iccc,
                ixf = Incc - Iccc,
                ixb = Iccc - Ipcc,
                iyf = Icnc - Iccc,
                iyb = Iccc - Icpc,
                izf = Iccn - Iccc,
                izb = Iccc - Iccp,
                itt = u*u*ixx + v*v*iyy + w*w*izz + 2*u*v*ixy + 2*u*w*ixz + 2*v*w*iyz,
                it = u*cimg::minmod(ixf,ixb) + v*cimg::minmod(iyf,iyb) + w*cimg::minmod(izf,izb),
                veloc = -amp*cimg::sign(itt)*cimg::abs(it);
              *(ptrd++) = veloc;
              if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
            }
            _veloc_max[c] = veloc_max;
          }
        } else // Inverse diffusion
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*512 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            Tfloat *ptrd = velocity.data(0,0,0,c), veloc_max = 0;
            CImg_3x3x3(I,Tfloat);
            cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) {
              const Tfloat veloc = -Ipcc - Incc - Icpc - Icnc - Iccp - Iccn + 6*Iccc;
              *(ptrd++) = veloc;
              if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
            }
            _veloc_max[c] = veloc_max;
          }
      } else { // 2D
        if (sharpen_type) { // Shock filters
          CImg<Tfloat> G = (alpha>0?get_blur(alpha).get_structure_tensors():get_structure_tensors());
          if (sigma>0) G.blur(sigma);
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*32 &&
                                                         _height>=(cimg_openmp_sizefactor)*16))
          cimg_forY(G,y) {
            CImg<Tfloat> val, vec;
            Tfloat *ptrG0 = G.data(0,y,0,0), *ptrG1 = G.data(0,y,0,1), *ptrG2 = G.data(0,y,0,2);
            cimg_forX(G,x) {
              G.get_tensor_at(x,y).symmetric_eigen(val,vec);
              if (val[0]<0) val[0] = 0;
              if (val[1]<0) val[1] = 0;
              *(ptrG0++) = vec(0,0);
              *(ptrG1++) = vec(0,1);
              *(ptrG2++) = 1 - (Tfloat)std::pow(1 + val[0] + val[1],-(Tfloat)nedge);
            }
          }
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*512 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            Tfloat *ptrd = velocity.data(0,0,0,c), veloc_max = 0;
            CImg_3x3(I,Tfloat);
            cimg_for3x3(*this,x,y,0,c,I,Tfloat) {
              const Tfloat
                u = G(x,y,0),
                v = G(x,y,1),
                amp = G(x,y,2),
                ixx = Inc + Ipc - 2*Icc,
                ixy = (Inn + Ipp - Inp - Ipn)/4,
                iyy = Icn + Icp - 2*Icc,
                ixf = Inc - Icc,
                ixb = Icc - Ipc,
                iyf = Icn - Icc,
                iyb = Icc - Icp,
                itt = u*u*ixx + v*v*iyy + 2*u*v*ixy,
                it = u*cimg::minmod(ixf,ixb) + v*cimg::minmod(iyf,iyb),
                veloc = -amp*cimg::sign(itt)*cimg::abs(it);
              *(ptrd++) = veloc;
              if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
            }
            _veloc_max[c] = veloc_max;
          }
        } else // Inverse diffusion
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*512 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            Tfloat *ptrd = velocity.data(0,0,0,c), veloc_max = 0;
            CImg_3x3(I,Tfloat);
            cimg_for3x3(*this,x,y,0,c,I,Tfloat) {
              const Tfloat veloc = -Ipc - Inc - Icp - Icn + 4*Icc;
              *(ptrd++) = veloc;
              if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
            }
            _veloc_max[c] = veloc_max;
          }
      }
      const Tfloat veloc_max = _veloc_max.max();
      if (veloc_max<=0) return *this;
      return ((velocity*=amplitude/veloc_max)+=*this).cut(val_min,val_max).move_to(*this);
    }

    //! Sharpen image \newinstance.
    CImg<T> get_sharpen(const float amplitude, const bool sharpen_type=false, const float edge=1,
                        const float alpha=0, const float sigma=0) const {
      return (+*this).sharpen(amplitude,sharpen_type,edge,alpha,sigma);
    }

    //! Return the image gradient.
    /**
       \param axes Axes considered for the gradient computation, as a C-string (e.g "xy").
       \param scheme = Numerical scheme used for the gradient computation:
       - -1 = Backward finite differences
       - 0 = Centered finite differences (default)
       - 1 = Forward finite differences
       - 2 = Using Sobel kernels
       - 3 = Using rotation invariant kernels
       - 4 = Using Deriche recursive filter.
       - 5 = Using Van Vliet recursive filter.
    **/
    CImgList<Tfloat> get_gradient(const char *const axes=0, const int scheme=0) const {
      CImgList<Tfloat> res;
      char __axes[4] = {};
      const char *_axes = axes?axes:__axes;
      if (!axes) {
        unsigned int k = 0;
        if (_width>1) __axes[k++] = 'x';
        if (_height>1) __axes[k++] = 'y';
        if (_depth>1) __axes[k++] = 'z';
      }

      CImg<Tfloat> grad;
      while (*_axes) {
        const char axis = cimg::lowercase(*(_axes++));
        if (axis!='x' && axis!='y' && axis!='z')
          throw CImgArgumentException(_cimg_instance
                                      "get_gradient(): Invalid specified axes '%s'.",
                                      cimg_instance,
                                      axes);
        const longT off = axis=='x'?1:axis=='y'?_width:_width*_height;
        if ((axis=='x' && _width==1) || (axis=='y' && _height==1) || (axis=='z' && _depth==1)) {
          grad.assign(_width,_height,_depth,_spectrum,0).move_to(res);
          continue;
        }

        const int _scheme = axis=='z' && (scheme==2 || scheme==3)?0:scheme;
        switch (_scheme) {
        case -1 : { // Backward finite differences
          grad.assign(_width,_height,_depth,_spectrum);
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(size(),16384))
          cimg_forXYZC(*this,x,y,z,c) {
            const ulongT pos = offset(x,y,z,c);
            if ((axis=='x' && !x) || (axis=='y' && !y) || (axis=='z' && !z))
              grad[pos] = 0;
            else
              grad[pos] = (Tfloat)_data[pos] - _data[pos - off];
          }
          grad.move_to(res);
        } break;
        case 1 : { // Forward finite differences
          grad.assign(_width,_height,_depth,_spectrum);
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(size(),16384))
          cimg_forXYZC(*this,x,y,z,c) {
            const ulongT pos = offset(x,y,z,c);
            if ((axis=='x' && x==width() - 1) || (axis=='y' && y==height() - 1) || (axis=='z' && z==depth() - 1))
              grad[pos] = 0;
            else
              grad[pos] = (Tfloat)_data[pos + off] - _data[pos];
          }
          grad.move_to(res);
        } break;
        case 2 : { // Sobel scheme
          grad.assign(_width,_height,_depth,_spectrum);
          if (axis=='x') // X-axis
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*16384 &&
                                              _depth*_spectrum>=2))
            cimg_forZC(*this,z,c) {
              CImg_3x3(I,Tfloat);
              cimg_for3x3(*this,x,y,z,c,I,Tfloat) grad(x,y,z,c) = - Ipp + Inp - 2*Ipc + 2*Inc - Ipn + Inn;
            }
          else // Y-axis
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*16384 &&
                                              _depth*_spectrum>=2))
            cimg_forZC(*this,z,c) {
              CImg_3x3(I,Tfloat);
              cimg_for3x3(*this,x,y,z,c,I,Tfloat) grad(x,y,z,c) = - Ipp - 2*Icp - Inp + Ipn + 2*Icn + Inn;
            }
          grad.move_to(res);
        } break;
        case 3 : { // Rotation invariant scheme
          const Tfloat a = (Tfloat)(0.25f*(2 - std::sqrt(2.f))), b = (Tfloat)(0.5f*(std::sqrt(2.f) - 1));
          grad.assign(_width,_height,_depth,_spectrum);
          if (axis=='x') // X-axis
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*16384 &&
                                              _depth*_spectrum>=2))
            cimg_forZC(*this,z,c) {
              CImg_3x3(I,Tfloat);
              cimg_for3x3(*this,x,y,z,c,I,Tfloat) grad(x,y,z,c) = -a*Ipp - b*Ipc - a*Ipn + a*Inp + b*Inc + a*Inn;
            }
          else // Y-axis
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*16384 &&
                                              _depth*_spectrum>=2))
            cimg_forZC(*this,z,c) {
              CImg_3x3(I,Tfloat);
              cimg_for3x3(*this,x,y,z,c,I,Tfloat) grad(x,y,z,c) = -a*Ipp - b*Icp - a*Inp + a*Ipn + b*Icn + a*Inn;
            }
          grad.move_to(res);
        } break;
        case 4 : // Deriche filter
          get_deriche(0,1,axis).move_to(res);
          break;
        case 5 : // Van Vliet filter
          get_vanvliet(0,1,axis).move_to(res);
          break;
        default : { // Central finite differences
          grad.assign(_width,_height,_depth,_spectrum);
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(size(),16384))
          cimg_forXYZC(*this,x,y,z,c) {
            const ulongT pos = offset(x,y,z,c);
            if ((axis=='x' && !x) || (axis=='y' && !y) || (axis=='z' && !z))
              grad[pos] = ((Tfloat)_data[pos + off] - _data[pos])/2;
            else if ((axis=='x' && x==width() - 1) || (axis=='y' && y==height() - 1) || (axis=='z' && z==depth() - 1))
              grad[pos] = ((Tfloat)_data[pos] - _data[pos - off])/2;
            else
              grad[pos] = ((Tfloat)_data[pos + off] - _data[pos - off])/2;
          }
          grad.move_to(res);
        } break;
        }
      }
      return res;
    }

    //! Return the image hessian.
    /**
       \param axes Axes considered for the hessian computation, as a C-string (e.g "xy").
    **/
    CImgList<Tfloat> get_hessian(const char *const axes=0) const {
      CImgList<Tfloat> res;
      char __axes[12] = {};
      const char *_axes = axes?axes:__axes;
      if (!axes) {
        unsigned int k = 0;
        if (_width>1) { __axes[k++] = 'x'; __axes[k++] = 'x'; }
        if (_width>1 && _height>1) { __axes[k++] = 'x'; __axes[k++] = 'y'; }
        if (_width>1 && _depth>1) { __axes[k++] = 'x'; __axes[k++] = 'z'; }
        if (_height>1) { __axes[k++] = 'y'; __axes[k++] = 'y'; }
        if (_height>1 && _depth>1) { __axes[k++] = 'y'; __axes[k++] = 'z'; }
        if (_depth>1) { __axes[k++] = 'z'; __axes[k++] = 'z'; }
      }
      const unsigned int len = (unsigned int)std::strlen(_axes);
      if (len%2)
        throw CImgArgumentException(_cimg_instance
                                    "get_hessian(): Invalid specified axes '%s'.",
                                    cimg_instance,
                                    axes);
      CImg<Tfloat> hess;
      for (unsigned int k = 0; k<len; k+=2) {
        const char
          _axis1 = cimg::lowercase(_axes[k]),
          _axis2 = cimg::lowercase(_axes[k + 1]),
          axis1 = std::min(_axis1,_axis2),
          axis2 = std::max(_axis2,_axis2);
        if (axis1!='x' && axis1!='y' && axis1!='z' &&
            axis2!='x' && axis2!='y' && axis2!='z')
          throw CImgArgumentException(_cimg_instance
                                      "get_hessian(): Invalid specified axes '%s'.",
                                      cimg_instance,
                                      axes);
        const longT off = axis1=='x'?1:axis1=='y'?_width:_width*_height;

        hess.assign(_width,_height,_depth,_spectrum);

        if (((axis1=='x' || axis2=='x') && _width==1) ||
            ((axis1=='y' || axis2=='y') && _height==1) ||
            ((axis1=='z' || axis2=='z') && _depth==1)) {
          hess.fill(0).move_to(res);
          continue;
        }

        if (axis1==axis2) // Ixx, Iyy, Izz
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(3) cimg_openmp_if_size(size(),16384))
          cimg_forXYZC(*this,x,y,z,c) {
            const ulongT pos = offset(x,y,z,c);
            if ((axis1=='x' && !x) || (axis1=='y' && !y) || (axis1=='z' && !z))
              hess[pos] = (Tfloat)_data[pos + off] - _data[pos];
            else if ((axis1=='x' && x==width() - 1) ||
                     (axis1=='y' && y==height() - 1) ||
                     (axis1=='z' && z==depth() - 1))
              hess[pos] = (Tfloat)_data[pos - off] - _data[pos];
            else
              hess[pos] = (Tfloat)_data[pos + off] + _data[pos - off] - 2*_data[pos];
          }
        else if (axis1=='x' && axis2=='y') // Ixy
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                             cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*16384 &&
                                            _depth*_spectrum>=2))
          cimg_forZC(*this,z,c) {
            CImg_3x3(I,Tfloat);
            cimg_for3x3(*this,x,y,z,c,I,Tfloat) hess(x,y,z,c) = (Inn + Ipp - Inp - Ipn)/4;
          }
        else if (axis1=='x' && axis2=='z') // Ixz
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*16384 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            CImg_3x3x3(I,Tfloat);
            cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) hess(x,y,z,c) = (Incn + Ipcp - Incp - Ipcn)/4;
          }
        else // Iyz
          cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*16384 &&
                                                         _spectrum>=2))
          cimg_forC(*this,c) {
            CImg_3x3x3(I,Tfloat);
            cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) hess(x,y,z,c) = (Icnn + Icpp - Icnp - Icpn)/4;
          }
        hess.move_to(res);
      }
      return res;
    }

    //! Compute image Laplacian.
    CImg<T>& laplacian() {
      return get_laplacian().move_to(*this);
    }

    //! Compute image Laplacian \newinstance.
    CImg<Tfloat> get_laplacian() const {
      if (is_empty()) return CImg<Tfloat>();
      CImg<Tfloat> res(_width,_height,_depth,_spectrum);
      if (_depth>1) { // 3D
        cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*1048576 &&
                                                       _spectrum>=2))
        cimg_forC(*this,c) {
          Tfloat *ptrd = res.data(0,0,0,c);
          CImg_3x3x3(I,Tfloat);
          cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) *(ptrd++) = Incc + Ipcc + Icnc + Icpc + Iccn + Iccp - 6*Iccc;
        }
      } else if (_height>1) { // 2D
        cimg_pragma_openmp(parallel for cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*1048576 &&
                                                       _depth*_spectrum>=2))
        cimg_forC(*this,c) {
          Tfloat *ptrd = res.data(0,0,0,c);
          CImg_3x3(I,Tfloat);
          cimg_for3x3(*this,x,y,0,c,I,Tfloat) *(ptrd++) = Inc + Ipc + Icn + Icp - 4*Icc;
        }
      } else { // 1D
        cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*1048576 &&
                                                       _height*_depth*_spectrum>=2))
        cimg_forC(*this,c) {
          Tfloat *ptrd = res.data(0,0,0,c);
          CImg_3x3(I,Tfloat);
          cimg_for3x3(*this,x,y,0,c,I,Tfloat) *(ptrd++) = Inc + Ipc - 2*Icc;
        }
      }
      return res;
    }

    //! Compute the structure tensor field of an image.
    /**
       \param is_fwbw_scheme scheme. Can be <tt>{ false=centered | true=forward-backward }</tt>
    **/
    CImg<T>& structure_tensors(const bool is_fwbw_scheme=false) {
      return get_structure_tensors(is_fwbw_scheme).move_to(*this);
    }

    //! Compute the structure tensor field of an image \newinstance.
    CImg<Tfloat> get_structure_tensors(const bool is_fwbw_scheme=false) const {
      if (is_empty()) return *this;
      CImg<Tfloat> res;
      if (_depth > 1) { // 3D version
        res.assign(_width,_height,_depth,6,0);
        if (!is_fwbw_scheme) { // Classical central finite differences
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                             cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*1048576))
          cimg_forYZ(*this,y,z) {
            Tfloat
              *ptrd0 = res.data(0,y,z,0), *ptrd1 = res.data(0,y,z,1), *ptrd2 = res.data(0,y,z,2),
              *ptrd3 = res.data(0,y,z,3), *ptrd4 = res.data(0,y,z,4), *ptrd5 = res.data(0,y,z,5);
            CImg_3x3x3(I,Tfloat);
            cimg_forX(*this,x) {
              cimg_def3x3x3(*this,x,y,z);
              Tfloat ix2 = 0, ixy = 0, ixz = 0, iy2 = 0, iyz = 0, iz2 = 0;
              cimg_forC(*this,c) {
                cimg_get3x3x3(*this,x,y,z,c,I,Tfloat);
                const Tfloat ix = (Incc - Ipcc)/2, iy = (Icnc - Icpc)/2, iz = (Iccn - Iccp)/2;
                ix2 += ix*ix; ixy += ix*iy; ixz += ix*iz;
                iy2 += iy*iy; iyz += iy*iz; iz2 += iz*iz;
              }
              *(ptrd0++) = ix2; *(ptrd1++) = ixy; *(ptrd2++) = ixz;
              *(ptrd3++) = iy2; *(ptrd4++) = iyz; *(ptrd5++) = iz2;
            }
          }
        } else { // Forward/backward finite differences
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                           cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*1048576))
        cimg_forYZ(*this,y,z) {
          Tfloat
            *ptrd0 = res.data(0,y,z,0), *ptrd1 = res.data(0,y,z,1), *ptrd2 = res.data(0,y,z,2),
            *ptrd3 = res.data(0,y,z,3), *ptrd4 = res.data(0,y,z,4), *ptrd5 = res.data(0,y,z,5);
          CImg_3x3x3(I,Tfloat);
          cimg_forX(*this,x) {
            cimg_def3x3x3(*this,x,y,z);
            Tfloat ix2 = 0, ixy = 0, ixz = 0, iy2 = 0, iyz = 0, iz2 = 0;
            cimg_forC(*this,c) {
              cimg_get3x3x3(*this,x,y,z,c,I,Tfloat);
              const Tfloat
                ixf = Incc - Iccc, ixb = Iccc - Ipcc, ixc = (Incc - Ipcc)/2,
                iyf = Icnc - Iccc, iyb = Iccc - Icpc, iyc = (Icnc - Icpc)/2,
                izf = Iccn - Iccc, izb = Iccc - Iccp, izc = (Iccn - Iccp)/2;
              ix2 += (ixf*ixf + ixb*ixb)/2; ixy += ixc*iyc; ixz += ixc*izc;
              iy2 += (iyf*iyf + iyb*iyb)/2; iyz += iyc*izc; iz2 += (izf*izf + izb*izb)/2;
            }
            *(ptrd0++) = ix2; *(ptrd1++) = ixy; *(ptrd2++) = ixz;
            *(ptrd3++) = iy2; *(ptrd4++) = iyz; *(ptrd5++) = iz2;
          }
        }
        }
      } else { // 2D version
        res.assign(_width,_height,_depth,3,0);
        if (!is_fwbw_scheme) { // Classical central finite differences
          cimg_pragma_openmp(parallel for
                             cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*1048576))
          cimg_forY(*this,y) {
            Tfloat *ptrd0 = res.data(0,y,0,0), *ptrd1 = res.data(0,y,0,1), *ptrd2 = res.data(0,y,0,2);
            CImg_3x3(I,Tfloat);
            cimg_forX(*this,x) {
              cimg_def3x3(*this,x,y);
              Tfloat ix2 = 0, ixy = 0, iy2 = 0;
              cimg_forC(*this,c) {
                cimg_get3x3(*this,x,y,0,c,I,Tfloat);
                const Tfloat ix = (Inc - Ipc)/2, iy = (Icn - Icp)/2;
                ix2 += ix*ix; ixy += ix*iy; iy2 += iy*iy;
              }
              *(ptrd0++) = ix2; *(ptrd1++) = ixy; *(ptrd2++) = iy2;
            }
          }
        } else { // Forward/backward finite differences
          cimg_pragma_openmp(parallel for
                             cimg_openmp_if(_width*_height>=(cimg_openmp_sizefactor)*1048576))
          cimg_forY(*this,y) {
            Tfloat *ptrd0 = res.data(0,y,0,0), *ptrd1 = res.data(0,y,0,1), *ptrd2 = res.data(0,y,0,2);
            CImg_3x3(I,Tfloat);
            cimg_forX(*this,x) {
              cimg_def3x3(*this,x,y);
              Tfloat ix2 = 0, ixy = 0, iy2 = 0;
              cimg_forC(*this,c) {
                cimg_get3x3(*this,x,y,0,c,I,Tfloat);
                const Tfloat
                  ixf = Inc - Icc, ixb = Icc - Ipc, ixc = (Inc - Ipc)/2,
                  iyf = Icn - Icc, iyb = Icc - Icp, iyc = (Icn - Icp)/2;
                ix2 += (ixf*ixf + ixb*ixb)/2; ixy += ixc*iyc; iy2 += (iyf*iyf + iyb*iyb)/2;
              }
              *(ptrd0++) = ix2; *(ptrd1++) = ixy; *(ptrd2++) = iy2;
            }
          }
        }
      }
      return res;
    }

    //! Compute field of diffusion tensors for edge-preserving smoothing.
    /**
       \param sharpness Sharpness
       \param anisotropy Anisotropy
       \param alpha Standard deviation of the gradient blur.
       \param sigma Standard deviation of the structure tensor blur.
       \param is_sqrt Indicates whether the square root of the tensor field is computed instead.
    **/
    CImg<T>& diffusion_tensors(const float sharpness=0.7f, const float anisotropy=0.6f,
                               const float alpha=0.6f, const float sigma=1.1f, const bool is_sqrt=false) {
      CImg<Tfloat> res;
      const float
        nsharpness = std::max(sharpness,1e-5f),
        power1 = (is_sqrt?0.5f:1)*nsharpness,
        power2 = power1/(1e-7f + 1 - anisotropy);
      blur(alpha).normalize(0,(T)255);

      if (_depth>1) { // 3D
        get_structure_tensors().move_to(res).blur(sigma);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                                   _height*_depth>=(cimg_openmp_sizefactor)*256))
        cimg_forYZ(*this,y,z) {
          Tfloat
            *ptrd0 = res.data(0,y,z,0), *ptrd1 = res.data(0,y,z,1), *ptrd2 = res.data(0,y,z,2),
            *ptrd3 = res.data(0,y,z,3), *ptrd4 = res.data(0,y,z,4), *ptrd5 = res.data(0,y,z,5);
          CImg<floatT> val(3), vec(3,3);
          cimg_forX(*this,x) {
            res.get_tensor_at(x,y,z).symmetric_eigen(val,vec);
            const float
              _l1 = val[2], _l2 = val[1], _l3 = val[0],
              l1 = _l1>0?_l1:0, l2 = _l2>0?_l2:0, l3 = _l3>0?_l3:0,
              ux = vec(0,0), uy = vec(0,1), uz = vec(0,2),
              vx = vec(1,0), vy = vec(1,1), vz = vec(1,2),
              wx = vec(2,0), wy = vec(2,1), wz = vec(2,2),
              n1 = (float)std::pow(1 + l1 + l2 + l3,-power1),
              n2 = (float)std::pow(1 + l1 + l2 + l3,-power2);
            *(ptrd0++) = n1*(ux*ux + vx*vx) + n2*wx*wx;
            *(ptrd1++) = n1*(ux*uy + vx*vy) + n2*wx*wy;
            *(ptrd2++) = n1*(ux*uz + vx*vz) + n2*wx*wz;
            *(ptrd3++) = n1*(uy*uy + vy*vy) + n2*wy*wy;
            *(ptrd4++) = n1*(uy*uz + vy*vz) + n2*wy*wz;
            *(ptrd5++) = n1*(uz*uz + vz*vz) + n2*wz*wz;
          }
        }
      } else { // for 2D images
        get_structure_tensors().move_to(res).blur(sigma);
        cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*256 &&
                                                       _height>=(cimg_openmp_sizefactor)*256))
        cimg_forY(*this,y) {
          Tfloat *ptrd0 = res.data(0,y,0,0), *ptrd1 = res.data(0,y,0,1), *ptrd2 = res.data(0,y,0,2);
          CImg<floatT> val(2), vec(2,2);
          cimg_forX(*this,x) {
            res.get_tensor_at(x,y).symmetric_eigen(val,vec);
            const float
              _l1 = val[1], _l2 = val[0],
              l1 = _l1>0?_l1:0, l2 = _l2>0?_l2:0,
              ux = vec(1,0), uy = vec(1,1),
              vx = vec(0,0), vy = vec(0,1),
              n1 = (float)std::pow(1 + l1 + l2,-power1),
              n2 = (float)std::pow(1 + l1 + l2,-power2);
            *(ptrd0++) = n1*ux*ux + n2*vx*vx;
            *(ptrd1++) = n1*ux*uy + n2*vx*vy;
            *(ptrd2++) = n1*uy*uy + n2*vy*vy;
          }
        }
      }
      return res.move_to(*this);
    }

    //! Compute field of diffusion tensors for edge-preserving smoothing \newinstance.
    CImg<Tfloat> get_diffusion_tensors(const float sharpness=0.7f, const float anisotropy=0.6f,
                                       const float alpha=0.6f, const float sigma=1.1f, const bool is_sqrt=false) const {
      return CImg<Tfloat>(*this,false).diffusion_tensors(sharpness,anisotropy,alpha,sigma,is_sqrt);
    }

    //! Estimate the displacement field from a given reference image to the current image instance.
    /**
       \param reference Reference image R.
       \param smoothness Smoothness of estimated displacement field.
       If smoothness is positive, Tikhonov regularization is applied, otherwise TV regularization is applied,
       with specified strength (absolute value of the smoothnes).
       \param precision Precision required for algorithm convergence.
       \param nb_scales Number of scales used to estimate the displacement field.
       \param iteration_max Maximum number of iterations allowed for one scale.
       \param is_forward If true, optimize (I(X + U(X)) - R(X)). If false, optimize (I(X) - R(X - U(X))).
       \param guide Image used as the initial correspondence estimate for the algorithm.
       'guide' may have a last channel with boolean values (0=false | other=true) that
       indicates for each pixel if its correspondence vector is constrained to its initial value (constraint mask).
    **/
    CImg<T>& displacement(const CImg<T>& reference, const float smoothness=0.1f, const float precision=7.f,
                          const unsigned int nb_scales=0, const unsigned int iteration_max=1000,
                          const bool is_forward=false,
                          const CImg<floatT>& guide=CImg<floatT>::const_empty()) {
      return get_displacement(reference,smoothness,precision,nb_scales,iteration_max,is_forward,guide).
        move_to(*this);
    }

    //! Estimate displacement field between two images \newinstance.
    CImg<Tfloat> get_displacement(const CImg<T>& reference,
                                  const float smoothness=0.1f, const float precision=7.f,
                                  const unsigned int nb_scales=0, const unsigned int iteration_max=1000,
                                  const bool is_forward=false,
                                  const CImg<floatT>& guide=CImg<floatT>::const_empty()) const {
      if (is_empty() || !reference) return +*this;
      if (!is_sameXYZC(reference))
        throw CImgArgumentException(_cimg_instance
                                    "displacement(): Instance and reference image (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    reference._width,reference._height,reference._depth,reference._spectrum,
                                    reference._data);
      if (precision<0)
        throw CImgArgumentException(_cimg_instance
                                    "displacement(): Invalid specified precision %g "
                                    "(should be >=0)",
                                    cimg_instance,
                                    precision);

      const double _precision = std::pow(10.,-(double)precision);
      const bool is_3d = _depth>1;
      const unsigned int spectrum_U = is_3d?3:2;

      if (guide &&
          (guide._width!=_width || guide._height!=_height || guide._depth!=_depth || guide._spectrum<spectrum_U))
        throw CImgArgumentException(_cimg_instance
                                    "displacement(): Specified guide (%u,%u,%u,%u,%p) "
                                    "has invalid dimensions.",
                                    cimg_instance,
                                    guide._width,guide._height,guide._depth,guide._spectrum,guide._data);

      const unsigned int
        min_siz = is_3d?cimg::min(_width,_height,_depth):std::min(_width,_height),
        _nb_scales = nb_scales?nb_scales:std::max(1U,(unsigned int)std::log2(min_siz) - 1U);

      CImg<Tfloat> U, V, C, Cv, Cm;  // U: vector field, V: velocity (-grad), C: constraints field (at current scale)
      for (int scale = (int)_nb_scales - 1; scale>=0; --scale) {
        const unsigned int
          fact = 1U<<scale,
          sw = std::max(1U,(unsigned int)((float)_width/fact)),
          sh = std::max(1U,(unsigned int)((float)_height/fact)),
          sd = std::max(1U,(unsigned int)((float)_depth/fact)),
          swhd = sw*sh*sd;

        if (sw<4 && sh<4 && (!is_3d || sd<4)) continue; // Skip too small scales
        const double precision_scale = _precision/fact;

        CImg<Tfloat> I = get_resize(sw,sh,sd,-100,2), R = reference.get_resize(sw,sh,sd,-100,2);
        Tfloat im, iM = (Tfloat)I.max_min(im);
        I/=std::max(std::abs(im),std::abs(iM));
        iM = (Tfloat)R.max_min(im);
        R/=std::max(std::abs(im),std::abs(iM));

        if (guide) {
          guide.get_resize(sw,sh,sd,-100,2).move_to(C);
          Cv.assign() = C.get_shared_channels(0,spectrum_U - 1)/=fact;
          if (guide._spectrum>spectrum_U) // Guide has constraints
            Cm.assign() = C.get_shared_channel(spectrum_U).normalize(0,1);
        }

        if (U) { // Upscale U
          const double vfact = cimg::min((double)sw/U._width,
                                         (double)sh/U._height,
                                         is_3d?(double)sd/U._depth:cimg::type<double>::inf());
          // ^^ 'vfact' should be close to '2', but slightly more precise.
          (U*=vfact).resize(sw,sh,sd,-100,3);
        } else { // Initialize U
          if (Cv) U = Cv; else U.assign(sw,sh,sd,spectrum_U,0);
        }

        V.assign(sw,sh,sd,U._spectrum); // Allocate V.
        const CImgList<Tfloat> grad = (is_forward?I:R).get_gradient(is_3d?"xyz":"xy",0);

        double prev_energy = cimg::type<float>::max(), dt = 0.5;

        const unsigned int nb_iterations = iteration_max==~0U?~0U:(iteration_max*fact);
        cimg_abort_init;

        for (unsigned int iteration = 0; iteration<nb_iterations; ++iteration) {
          cimg_abort_test;
          double energy = 0;

          if (is_3d) { // 3D version
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                               cimg_openmp_if(_height*_depth>=(cimg_openmp_sizefactor)*8 &&
                                              _width>=(cimg_openmp_sizefactor)*16)
                               reduction(+:energy))
            cimg_forYZ(U,y,z) {
              const int
                _p1y = y?y - 1:0, _n1y = y<U.height() - 1?y + 1:y,
                _p1z = z?z - 1:0, _n1z = z<U.depth() - 1?z + 1:z;
              cimg_for3X(U,x) {
                const double
                  sx = is_forward?x + U(x,y,z,0):x - U(x,y,z,0),
                  sy = is_forward?y + U(x,y,z,1):y - U(x,y,z,1),
                  sz = is_forward?z + U(x,y,z,2):z - U(x,y,z,2);
                double _V[3] = { 0 };

                // Data term.
                cimg_forC(I,c) {
                  const double delta = (double)(is_forward?R(x,y,z,c) - I._linear_atXYZ(sx,sy,sz,c):
                                                R._linear_atXYZ(sx,sy,sz,c) - I(x,y,z,c));
                  energy+=delta*delta;
                  _V[0]+=delta*grad[0].linear_atXYZ(sx,sy,sz,c,0);
                  _V[1]+=delta*grad[1].linear_atXYZ(sx,sy,sz,c,0);
                  _V[2]+=delta*grad[2].linear_atXYZ(sx,sy,sz,c,0);
                }

                // Regularization term.
                if (smoothness>0) cimg_forC(U,c) { // Tikhonov
                    const double
                      uccc = U(x,y,z,c),
                      upcc = U(_p1x,y,z,c), uncc = U(_n1x,y,z,c),
                      ucpc = U(x,_p1y,z,c), ucnc = U(x,_n1y,z,c),
                      uccp = U(x,y,_p1z,c), uccn = U(x,y,_n1z,c),
                      ux = 0.5*(uncc - upcc), uy = 0.5*(ucnc - ucpc), uz = 0.5*(uccn - uccp);
                    energy+=smoothness*(ux*ux + uy*uy + uz*uz);
                    _V[c]+=smoothness*(upcc + uncc + ucpc + ucnc + uccp + uccn - 6*uccc);
                  } else if (smoothness<0) cimg_forC(U,c) { // Total variation
                    const double
                      ucpp = U(x,_p1y,_p1z,c),
                      upcp = U(_p1x,y,_p1z,c), uccp = U(x,y,_p1z,c), uncp = U(_n1x,y,_p1z,c),
                      ucnp = U(x,_n1y,_p1z,c),
                      uppc = U(_p1x,_p1y,z,c), ucpc = U(x,_p1y,z,c), unpc = U(_n1x,_p1y,z,c),
                      upcc = U(_p1x,y,z,c), uccc = U(x,y,z,c), uncc = U(_n1x,y,z,c),
                      upnc = U(_p1x,_n1y,z,c), ucnc = U(x,_n1y,z,c), unnc = U(_n1x,_n1y,z,c),
                      ucpn = U(x,_p1y,_n1z,c),
                      upcn = U(_p1x,y,_n1z,c), uccn = U(x,y,_n1z,c), uncn = U(_n1x,y,_n1z,c),
                      ucnn = U(x,_n1y,_n1z,c),
                      ux = 0.5*(uncc - upcc), uy = 0.5*(ucnc - ucpc), uz = 0.5*(uccn - uccp),
                      gn = 1e-8 + std::sqrt(ux*ux + uy*uy + uz*uz),
                      nux = ux/gn, nuy = uy/gn, nuz = uz/gn,
                      uxx = uncc + upcc - 2*uccc,
                      uxy = 0.25*(uppc + unnc - upnc - unpc),
                      uxz = 0.25*(upcp + uncn - upcn - uncp),
                      uyy = ucnc + ucpc - 2*uccc,
                      uyz = 0.25*(ucpp + ucnn - ucpn - ucnp),
                      uzz = uccn + uccp - 2*uccc,
                      unn = nux*nux*uxx + nuy*nuy*uyy + nuz*nuz*uzz + 2*(nux*nuy*uxy + nux*nuz*uxz + nuy*nuz*uyz),
                      uee = uxx + uyy + uzz - unn;
                    energy-=smoothness*gn;
                    _V[c]-=smoothness*(uee/gn);
                  }

                // Guide term.
                if (C) {
                  const double w = Cm(x,y,z);
                  if (w>0) cimg_forC(U,c) {
                      const double diff = (double)C(x,y,z,c) - U(x,y,z,c);
                      energy+=w*diff*diff;
                      _V[c]+=w*diff;
                    }
                }

                V(x,y,z,0) = (Tfloat)_V[0];
                V(x,y,z,1) = (Tfloat)_V[1];
                V(x,y,z,2) = (Tfloat)_V[2];
              }
            }

          } else { // 2D version
            cimg_pragma_openmp(parallel for cimg_openmp_if(_height>=(cimg_openmp_sizefactor)*8 &&
                                                           _width>=(cimg_openmp_sizefactor)*16)
                               reduction(+:energy))
            cimg_forY(U,y) {
              const int _p1y = y?y - 1:0, _n1y = y<U.height() - 1?y + 1:y;
              cimg_for3X(U,x) {
                const double
                  sx = is_forward?x + U(x,y,0):x - U(x,y,0),
                  sy = is_forward?y + U(x,y,1):y - U(x,y,1);
                double _V[2] = { 0 };

                // Data term.
                cimg_forC(I,c) {
                  const double delta = (double)(is_forward?R(x,y,c) - I._linear_atXY(sx,sy,0,c):
                                                R._linear_atXY(sx,sy,0,c) - I(x,y,c));
                  energy+=delta*delta;
                  _V[0]+=delta*grad[0].linear_atXY(sx,sy,0,c,0);
                  _V[1]+=delta*grad[1].linear_atXY(sx,sy,0,c,0);
                }

                // Regularization term.
                if (smoothness>0) cimg_forC(U,c) { // Tikhonov
                    const double
                      ucc = U(x,y,c),
                      upc = U(_p1x,y,c), unc = U(_n1x,y,c),
                      ucp = U(x,_p1y,c), ucn = U(x,_n1y,c),
                      ux = 0.5*(unc - upc), uy = 0.5*(ucn - ucp);
                    energy+=smoothness*(ux*ux + uy*uy);
                    _V[c]+=smoothness*(upc + unc + ucp + ucn - 4*ucc);
                  } else if (smoothness<0) cimg_forC(U,c) { // Total variation
                    const double
                      upp = U(_p1x,_p1y,c), ucp = U(x,_p1y,c), unp = U(_n1x,_p1y,c),
                      upc = U(_p1x,y,c), ucc = U(x,y,c), unc = U(_n1x,y,c),
                      upn = U(_p1x,_n1y,c), ucn = U(x,_n1y,c), unn = U(_n1x,_n1y,c),
                      ux = 0.5*(unc - upc), uy = 0.5*(ucn - ucp),
                      gn = 1e-8 + std::sqrt(ux*ux + uy*uy),
                      nux = ux/gn, nuy = uy/gn,
                      uxx = unc + upc - 2*ucc,
                      uxy = 0.25*(upp + unn - upn - unp),
                      uyy = ucn + ucp - 2*ucc,
                      uee = nuy*nuy*uxx + nux*nux*uyy - 2*nux*nuy*uxy;
                    energy-=smoothness*gn;
                    _V[c]-=smoothness*(uee/gn);
                  }

                // Guide term.
                if (C) {
                  const double w = Cm(x,y);
                  if (w>0) cimg_forC(U,c) {
                      const double diff = (double)C(x,y,c) - U(x,y,c);
                      energy+=w*diff*diff;
                      _V[c]+=w*diff;
                    }
                }

                V(x,y,0) = (Tfloat)_V[0];
                V(x,y,1) = (Tfloat)_V[1];
              }
            }
          }

          energy/=swhd;

          // Update displacement field.
          Tfloat Vmin,Vmax = V.max_min(Vmin);
          const double dt_iteration = dt/cimg::max((Tfloat)1e-8,cimg::abs(Vmin),cimg::abs(Vmax));
          cimg_openmp_for(U,*ptr + dt_iteration*V[ptr - U._data],32768,float);

          // Force guided constraints even a bit more to speed up convergence.
          if (C) U.draw_image(0,0,0,0,Cv,Cm,1,1);

          // Test convergence.
          if (iteration) {
            const double d_energy = energy - prev_energy;
            if (energy<precision_scale || (d_energy<=0 && -d_energy<precision_scale)) break;
            if (d_energy>0) { dt*=0.5; if (dt<1e-8) break; }
            else if (d_energy<0) dt = std::min(0.5,1.25*dt);
          }
          prev_energy = energy;
          if (iteration==~0U-1) --iteration; // Allow infinite iterations when max_iteration=~0U
        }
      }
      return U;
    }

    //! Compute correspondence map between two images, using a patch-matching algorithm.
    /**
        \param patch_image The image containing the reference patches to match with the instance image.
        \param patch_width Width of the patch used for matching.
        \param patch_height Height of the patch used for matching.
        \param patch_depth Depth of the patch used for matching.
        \param nb_iterations Number of patch-match iterations.
        \param nb_randoms Number of randomization attempts (per pixel).
        \param patch_penalization Penalization factor in score related patch occurrences.
               if negative, also indicates that identity result is not avoided.
        \param guide Image used as the initial correspondence estimate for the algorithm.
          'guide' may have a last channel with boolean values (0=false | other=true) that
          indicates for each pixel if its correspondence vector is constrained to its initial value (constraint mask).
        \param[out] matching_score Returned as the image of matching scores.
    **/
    template<typename t1, typename t2>
    CImg<T>& matchpatch(const CImg<T>& patch_image,
                        const unsigned int patch_width,
                        const unsigned int patch_height,
                        const unsigned int patch_depth,
                        const unsigned int nb_iterations,
                        const unsigned int nb_randoms,
                        const float patch_penalization,
                        const CImg<t1> &guide,
                        CImg<t2> &matching_score) {
      return get_matchpatch(patch_image,patch_width,patch_height,patch_depth,
                            nb_iterations,nb_randoms,patch_penalization,guide,matching_score).move_to(*this);
    }

    //! Compute correspondence map between two images, using the patch-match algorithm \newinstance.
    template<typename t1, typename t2>
    CImg<intT> get_matchpatch(const CImg<T>& patch_image,
                              const unsigned int patch_width,
                              const unsigned int patch_height,
                              const unsigned int patch_depth,
                              const unsigned int nb_iterations,
                              const unsigned int nb_randoms,
                              const float patch_penalization,
                              const CImg<t1> &guide,
                              CImg<t2> &matching_score) const {
      return _matchpatch(patch_image,patch_width,patch_height,patch_depth,
                         nb_iterations,nb_randoms,patch_penalization,
                         guide,true,matching_score);
    }

    //! Compute correspondence map between two images, using the patch-match algorithm \overload.
    template<typename t>
    CImg<T>& matchpatch(const CImg<T>& patch_image,
                        const unsigned int patch_width,
                        const unsigned int patch_height,
                        const unsigned int patch_depth,
                        const unsigned int nb_iterations=5,
                        const unsigned int nb_randoms=5,
                        const float patch_penalization=0,
                        const CImg<t> &guide=CImg<t>::const_empty()) {
      return get_matchpatch(patch_image,patch_width,patch_height,patch_depth,
                            nb_iterations,nb_randoms,patch_penalization,guide).move_to(*this);
    }

    //! Compute correspondence map between two images, using the patch-match algorithm \overload.
    template<typename t>
    CImg<intT> get_matchpatch(const CImg<T>& patch_image,
                              const unsigned int patch_width,
                              const unsigned int patch_height,
                              const unsigned int patch_depth,
                              const unsigned int nb_iterations=5,
                              const unsigned int nb_randoms=5,
                              const float patch_penalization=0,
                              const CImg<t> &guide=CImg<t>::const_empty()) const {
      CImg<T> matching_score;
      return _matchpatch(patch_image,patch_width,patch_height,patch_depth,
                         nb_iterations,nb_randoms,patch_penalization,guide,false,matching_score);
    }

    template<typename t1, typename t2>
    CImg<intT> _matchpatch(const CImg<T>& patch_image,
                           const unsigned int patch_width,
                           const unsigned int patch_height,
                           const unsigned int patch_depth,
                           const unsigned int nb_iterations,
                           const unsigned int nb_randoms,
                           const float patch_penalization,
                           const CImg<t1> &guide,
                           const bool is_matching_score,
                           CImg<t2> &matching_score) const {
      if (is_empty()) return CImg<intT>::const_empty();
      if (patch_image._spectrum!=_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "matchpatch(): Instance image and specified patch image (%u,%u,%u,%u,%p) "
                                    "have different spectrums.",
                                    cimg_instance,
                                    patch_image._width,patch_image._height,patch_image._depth,patch_image._spectrum,
                                    patch_image._data);
      if (patch_width>_width || patch_height>_height || patch_depth>_depth)
        throw CImgArgumentException(_cimg_instance
                                    "matchpatch(): Specified patch size %ux%ux%u is bigger than the dimensions "
                                    "of the instance image.",
                                    cimg_instance,patch_width,patch_height,patch_depth);
      if (patch_width>patch_image._width || patch_height>patch_image._height || patch_depth>patch_image._depth)
        throw CImgArgumentException(_cimg_instance
                                    "matchpatch(): Specified patch size %ux%ux%u is bigger than the dimensions "
                                    "of the patch image image (%u,%u,%u,%u,%p).",
                                    cimg_instance,patch_width,patch_height,patch_depth,
                                    patch_image._width,patch_image._height,patch_image._depth,patch_image._spectrum,
                                    patch_image._data);
      const unsigned int
        _constraint = patch_image._depth>1?3:2,
        constraint = guide._spectrum>_constraint?_constraint:0;

      if (guide &&
          (guide._width!=_width || guide._height!=_height || guide._depth!=_depth || guide._spectrum<_constraint))
        throw CImgArgumentException(_cimg_instance
                                    "matchpatch(): Specified guide (%u,%u,%u,%u,%p) has invalid dimensions "
                                    "considering instance and patch image (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    guide._width,guide._height,guide._depth,guide._spectrum,guide._data,
                                    patch_image._width,patch_image._height,patch_image._depth,patch_image._spectrum,
                                    patch_image._data);

      CImg<intT> a_map(_width,_height,_depth,patch_image._depth>1?3:2);
      CImg<ucharT> is_updated(_width,_height,_depth,1,3);
      CImg<floatT> score(_width,_height,_depth), penalty;
      const float _patch_penalization = cimg::abs(patch_penalization);
      const bool allow_identity = patch_penalization>=0;
      if (_patch_penalization!=0)
        penalty.assign(patch_image._width,patch_image._height,patch_image._depth,1,0);

      const int
        psizew = (int)patch_width,  psizew1 = psizew/2, psizew2 = psizew - psizew1 - 1,
        psizeh = (int)patch_height, psizeh1 = psizeh/2, psizeh2 = psizeh - psizeh1 - 1,
        psized = (int)patch_depth,  psized1 = psized/2, psized2 = psized - psized1 - 1;

      // Interleave image buffers to speed up patch comparison (more cache-friendly).
      CImg<T> in_this = get_permute_axes("cxyz");
      in_this._width = _width*_spectrum;
      in_this._height = _height;
      in_this._depth = _depth;
      in_this._spectrum = 1;
      CImg<T> in_patch = patch_image.get_permute_axes("cxyz");
      in_patch._width = patch_image._width*patch_image._spectrum;
      in_patch._height = patch_image._height;
      in_patch._depth = patch_image._depth;
      in_patch._spectrum = 1;

      if (_depth>1 || patch_image._depth>1) { // 3D version

        // Initialize correspondence map.
        if (guide)
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if_size(_width,64))
          cimg_forXYZ(*this,x,y,z) { // User-defined initialization
            const int
              cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
              cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
              cz1 = z<=psized1?z:(z<depth()  - psized2?psized1:psized + z - depth()),  cz2 = psized - cz1 - 1,
              u = cimg::cut((int)guide(x,y,z,0),cx1,patch_image.width() - 1 - cx2),
              v = cimg::cut((int)guide(x,y,z,1),cy1,patch_image.height() - 1 - cy2),
              w = cimg::cut((int)guide(x,y,z,2),cz1,patch_image.depth() - 1 - cz2);
            a_map(x,y,z,0) = u;
            a_map(x,y,z,1) = v;
            a_map(x,y,z,2) = w;
            score(x,y,z) = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                       x - cx1,y - cy1,z - cz1,
                                       u - cx1,v - cy1,w - cz1,
                                       u,v,w,0,allow_identity,cimg::type<float>::inf());
          } else cimg_pragma_openmp(parallel cimg_openmp_if_size(_width,64)) {
            cimg_uint64 rng = (cimg::_rand(),cimg::rng());
#if cimg_use_openmp!=0
            rng+=omp_get_thread_num();
#endif
            cimg_pragma_openmp(for cimg_openmp_collapse(2))
            cimg_forXYZ(*this,x,y,z) { // Random initialization
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
                cz1 = z<=psized1?z:(z<depth()  - psized2?psized1:psized + z - depth()),  cz2 = psized - cz1 - 1,
                u = (int)cimg::round(cimg::rand(cx1,patch_image.width() - 1 - cx2,&rng)),
                v = (int)cimg::round(cimg::rand(cy1,patch_image.height() - 1 - cy2,&rng)),
                w = (int)cimg::round(cimg::rand(cz1,patch_image.depth() - 1 - cz2,&rng));
              a_map(x,y,z,0) = u;
              a_map(x,y,z,1) = v;
              a_map(x,y,z,2) = w;
              score(x,y,z) = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                         x - cx1,y - cy1,z - cz1,
                                         u - cx1,v - cy1,w - cz1,
                                         u,v,w,0,allow_identity,cimg::type<float>::inf());
            }
            cimg::srand(rng);
          }

        // Start iteration loop.
        cimg_abort_init;
        for (unsigned int iter = 0; iter<nb_iterations; ++iter) {
          cimg_abort_test;
          const bool is_backward = iter&1, is_forward = !is_backward;
          const unsigned int cmask = is_backward?1:2, nmask = 3 - cmask;

          cimg_pragma_openmp(parallel cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64)) {
            cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
            rng+=omp_get_thread_num();
#endif
            cimg_pragma_openmp(for cimg_openmp_collapse(2))
            cimg_forXYZ(*this,X,Y,Z) {
              const int
                x = is_backward?width() - 1 - X:X,
                y = is_backward?height() - 1 - Y:Y,
                z = is_backward?depth() - 1 - Z:Z;
              if (score(x,y,z)<=1e-5 || (constraint && guide(x,y,z,constraint)!=0)) continue;
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
                cz1 = z<=psized1?z:(z<depth()  - psized2?psized1:psized + z - depth()),  cz2 = psized - cz1 - 1,
                xp = x - cx1,
                yp = y - cy1,
                zp = z - cz1;

              int best_u = a_map(x,y,z,0), best_v = a_map(x,y,z,1), best_w = a_map(x,y,z,2), u, v, w;
              const float best_score0 = score(x,y,z);
              float best_score = best_score0, s;

              if (is_forward && x>0 && (is_updated(x - 1,y,z)&cmask)) { // Compare with left neighbor
                u = a_map(x - 1,y,z,0);
                v = a_map(x - 1,y,z,1);
                w = a_map(x - 1,y,z,2);
                if (u>=cx1 - 1 && u<patch_image.width() - 1 - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2 &&
                    w>=cz1 && w<patch_image.depth() - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u + 1 - cx1,v - cy1,w - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u + 1; best_v = v; best_w = w; best_score = s; }
                }
              }
              if (is_forward && y>0 && (is_updated(x,y - 1,z)&cmask)) { // Compare with up neighbor
                u = a_map(x,y - 1,z,0);
                v = a_map(x,y - 1,z,1);
                w = a_map(x,y - 1,z,2);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 - 1 && v<patch_image.height() - 1 - cy2 &&
                    w>=cz1 && w<patch_image.depth() - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - cx1,v + 1 - cy1,w - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v + 1; best_w = w; best_score = s; }
                }
              }
              if (is_forward && z>0 && (is_updated(x,y,z - 1)&cmask)) { // Compare with backward neighbor
                u = a_map(x,y,z - 1,0);
                v = a_map(x,y,z - 1,1);
                w = a_map(x,y,z - 1,2);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2 &&
                    w>=cz1 - 1 && w<patch_image.depth() - 1 - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - cx1,v - cy1,w + 1 - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v; best_w = w + 1; best_score = s; }
                }
              }
              if (is_backward && x<width() - 1 && (is_updated(x + 1,y,z)&cmask)) { // Compare with right neighbor
                u = a_map(x + 1,y,z,0);
                v = a_map(x + 1,y,z,1);
                w = a_map(x + 1,y,z,2);
                if (u>=cx1 + 1 && u<patch_image.width() + 1 - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2 &&
                    w>=cz1 && w<patch_image.depth() - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - 1 - cx1,v - cy1,w - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u - 1; best_v = v; best_w = w; best_score = s; }
                }
              }
              if (is_backward && y<height() - 1 && (is_updated(x,y + 1,z)&cmask)) { // Compare with bottom neighbor
                u = a_map(x,y + 1,z,0);
                v = a_map(x,y + 1,z,1);
                w = a_map(x,y + 1,z,2);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 + 1 && v<patch_image.height() + 1 - cy2 &&
                    w>=cz1 && w<patch_image.depth() - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - cx1,v - 1 - cy1,w - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v - 1; best_w = w; best_score = s; }
                }
              }
              if (is_backward && z<depth() - 1 && (is_updated(x,y,z + 1)&cmask)) { // Compare with forward neighbor
                u = a_map(x,y,z + 1,0);
                v = a_map(x,y,z + 1,1);
                w = a_map(x,y,z + 1,2);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2 &&
                    w>=cz1 + 1 && w<patch_image.depth() + 1 - cz2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - cx1,v - cy1,w - 1 - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v; best_w = w - 1; best_score = s; }
                }
              }

              float
                dw = (float)patch_image.width(),
                dh = (float)patch_image.height(),
                dd = (float)patch_image.depth();
              for (unsigned int i = 0; i<nb_randoms; ++i) {
                u = (int)cimg::round(cimg::rand(std::max((float)cx1,best_u - dw),
                                                std::min(patch_image.width() - 1.f - cx2,best_u + dw),&rng));
                v = (int)cimg::round(cimg::rand(std::max((float)cy1,best_v - dh),
                                                std::min(patch_image.height() - 1.f - cy2,best_v + dh),&rng));
                w = (int)cimg::round(cimg::rand(std::max((float)cz1,best_w - dd),
                                                std::min(patch_image.depth() - 1.f - cz2,best_w + dd),&rng));
                if (u!=best_u || v!=best_v || w!=best_w) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                  xp,yp,zp,u - cx1,v - cy1,w - cz1,
                                  u,v,w,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v; best_w = w; best_score = s; }
                  dw = std::max(5.f,dw*0.5f); dh = std::max(5.f,dh*0.5f); dd = std::max(5.f,dd*0.5f);
                }
              }

              if (best_score<best_score0) {
                if (_patch_penalization!=0) {
                  float &p_penalty = penalty(a_map(x,y,z,0),a_map(x,y,z,1),a_map(x,y,z,2));
                  if (p_penalty) cimg_pragma_openmp(atomic) --p_penalty;
                }
                a_map(x,y,z,0) = best_u;
                a_map(x,y,z,1) = best_v;
                a_map(x,y,z,2) = best_w;
                score(x,y,z) = best_score;
                is_updated(x,y,z) = 3;
              } else is_updated(x,y,z)&=~nmask;
              if (_patch_penalization!=0) cimg_pragma_openmp(atomic) ++penalty(best_u,best_v,best_w);
            }
            cimg::srand(rng);
          }

          // Update score according to new penalties.
          if (penalty)
            cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64))
            cimg_forXYZ(score,x,y,z) {
              const float p_score = score(x,y,z);
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()),
                cz1 = z<=psized1?z:(z<depth()  - psized2?psized1:psized + z - depth()),
                xp = x - cx1,
                yp = y - cy1,
                zp = z - cz1,
                u = a_map(x,y,z,0),
                v = a_map(x,y,z,1),
                w = a_map(x,y,z,2);
              const float n_score = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,patch_depth,_spectrum,
                                                xp,yp,zp,u - cx1,v - cy1,w - cz1,
                                                u,v,w,_patch_penalization,allow_identity,cimg::type<float>::inf());
              if (n_score!=p_score) { score(x,y,z) = n_score; is_updated(x,y) = 3; }
            }
        }

      } else { // 2D version

        // Initialize correspondence map.
        if (guide)
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(_width,64))
          cimg_forXY(*this,x,y) { // User-defined initialization
            const int
              cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
              cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
              u = cimg::cut((int)guide(x,y,0),cx1,patch_image.width() - 1 - cx2),
              v = cimg::cut((int)guide(x,y,1),cy1,patch_image.height() - 1 - cy2);
            a_map(x,y,0) = u;
            a_map(x,y,1) = v;
            score(x,y) = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                     x - cx1,y - cy1,u - cx1,v - cy1,
                                     u,v,0,allow_identity,cimg::type<float>::inf());
          } else cimg_pragma_openmp(parallel cimg_openmp_if_size(_width,64)) {
            cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
            rng+=omp_get_thread_num();
#endif
            cimg_pragma_openmp(for)
            cimg_forXY(*this,x,y) { // Random initialization
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
                u = (int)cimg::round(cimg::rand(cx1,patch_image.width() - 1 - cx2,&rng)),
                v = (int)cimg::round(cimg::rand(cy1,patch_image.height() - 1 - cy2,&rng));
              a_map(x,y,0) = u;
              a_map(x,y,1) = v;
              score(x,y) = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                       x - cx1,y - cy1,u - cx1,v - cy1,
                                       u,v,0,allow_identity,cimg::type<float>::inf());
            }
            cimg::srand(rng);
          }

        // Start iteration loop.
        cimg_abort_init;
        for (unsigned int iter = 0; iter<nb_iterations; ++iter) {
          cimg_abort_test;
          const bool is_backward = iter&1, is_forward = !is_backward;
          const unsigned int cmask = is_backward?1:2, nmask = 3 - cmask;

          cimg_pragma_openmp(parallel cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64)) {
            cimg_uint64 rng = (cimg::_rand(),cimg::rng());

#if cimg_use_openmp!=0
            rng+=omp_get_thread_num();
#endif
            cimg_pragma_openmp(for)
            cimg_forXY(*this,X,Y) {
              const int
                x = is_backward?width() - 1 - X:X,
                y = is_backward?height() - 1 - Y:Y;
              if (score(x,y)<=1e-5 || (constraint && guide(x,y,constraint)!=0)) continue;
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),  cx2 = psizew - cx1 - 1,
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()), cy2 = psizeh - cy1 - 1,
                xp = x - cx1,
                yp = y - cy1;

              int best_u = a_map(x,y,0), best_v = a_map(x,y,1), u, v;
              const float best_score0 = score(x,y);
              float best_score = best_score0, s;

              if (is_forward && x>0 && (is_updated(x - 1,y)&cmask)) { // Compare with left neighbor
                u = a_map(x - 1,y,0);
                v = a_map(x - 1,y,1);
                if (u>=cx1 - 1 && u<patch_image.width() - 1 - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                  xp,yp,u + 1 - cx1,v - cy1,
                                  u,v,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u + 1; best_v = v; best_score = s; }
                }
              }
              if (is_forward && y>0 && (is_updated(x,y - 1)&cmask)) { // Compare with up neighbor
                u = a_map(x,y - 1,0);
                v = a_map(x,y - 1,1);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 - 1 && v<patch_image.height() - 1 - cy2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                  xp,yp,u - cx1,v + 1 - cy1,
                                  u,v,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v + 1; best_score = s; }
                }
              }
              if (is_backward && x<width() - 1 && (is_updated(x + 1,y)&cmask)) { // Compare with right neighbor
                u = a_map(x + 1,y,0);
                v = a_map(x + 1,y,1);
                if (u>=cx1 + 1 && u<patch_image.width() + 1 - cx2 &&
                    v>=cy1 && v<patch_image.height() - cy2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                  xp,yp,u - 1 - cx1,v - cy1,
                                  u,v,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u - 1; best_v = v; best_score = s; }
                }
              }
              if (is_backward && y<height() - 1 && (is_updated(x,y + 1)&cmask)) { // Compare with bottom neighbor
                u = a_map(x,y + 1,0);
                v = a_map(x,y + 1,1);
                if (u>=cx1 && u<patch_image.width() - cx2 &&
                    v>=cy1 + 1 && v<patch_image.height() + 1 - cy2) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                  xp,yp,u - cx1,v - 1 - cy1,
                                  u,v,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v - 1; best_score = s; }
                }
              }

              float
                dw = (float)patch_image.width(),
                dh = (float)patch_image.height();
              for (unsigned int i = 0; i<nb_randoms; ++i) {
                u = (int)cimg::round(cimg::rand(std::max((float)cx1,best_u - dw),
                                                std::min(patch_image.width() - 1.f - cx2,best_u + dw),&rng));
                v = (int)cimg::round(cimg::rand(std::max((float)cy1,best_v - dh),
                                                std::min(patch_image.height() - 1.f - cy2,best_v + dh),&rng));
                if (u!=best_u || v!=best_v) {
                  s = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                  xp,yp,u - cx1,v - cy1,
                                  u,v,_patch_penalization,allow_identity,best_score);
                  if (s<best_score) { best_u = u; best_v = v; best_score = s; }
                  dw = std::max(5.f,dw*0.5f); dh = std::max(5.f,dh*0.5f);
                }
              }

              if (best_score<best_score0) {
                if (_patch_penalization!=0) {
                  float &p_penalty = penalty(a_map(x,y,0),a_map(x,y,1));
                  if (p_penalty) cimg_pragma_openmp(atomic) --p_penalty;
                }
                a_map(x,y,0) = best_u;
                a_map(x,y,1) = best_v;
                score(x,y) = best_score;
                is_updated(x,y) = 3;
              } else is_updated(x,y)&=~nmask;
              if (_patch_penalization!=0) cimg_pragma_openmp(atomic) ++penalty(best_u,best_v);
            }
            cimg::srand(rng);
          }

          // Update score according to new penalties.
          if (penalty)
            cimg_pragma_openmp(parallel for cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*64))
            cimg_forXY(score,x,y) {
              const float p_score = score(x,y);
              const int
                cx1 = x<=psizew1?x:(x<width()  - psizew2?psizew1:psizew + x - width()),
                cy1 = y<=psizeh1?y:(y<height() - psizeh2?psizeh1:psizeh + y - height()),
                xp = x - cx1,
                yp = y - cy1,
                u = a_map(x,y,0),
                v = a_map(x,y,1);
              const float n_score = _matchpatch(in_this,in_patch,penalty,patch_width,patch_height,_spectrum,
                                                xp,yp,u - cx1,v - cy1,
                                                u,v,_patch_penalization,allow_identity,cimg::type<float>::inf());
              if (n_score!=p_score) { score(x,y) = n_score; is_updated(x,y) = 3; }
            }
        }
      }

      if (is_matching_score) score.move_to(matching_score);
      return a_map;
    }

    // Compute SSD between two patches in different images.
    static float _matchpatch(const CImg<T>& img1, const CImg<T>& img2, const CImg<floatT>& penalty,
                             const unsigned int psizew, const unsigned int psizeh,
                             const unsigned int psized, const unsigned int psizec,
                             const int x1, const int y1, const int z1,
                             const int x2, const int y2, const int z2,
                             const int xc, const int yc, const int zc,
                             const float patch_penalization,
                             const bool allow_identity,
                             const float max_score) { // 3D version
      if (!allow_identity && cimg::hypot((float)x1 - x2,(float)y1 - y2,(float)z1 - z2)<patch_penalization)
        return cimg::type<float>::inf();
      const T *p1 = img1.data(x1*psizec,y1,z1), *p2 = img2.data(x2*psizec,y2,z2);
      const unsigned int psizewc = psizew*psizec;
      const ulongT
        offx1 = (ulongT)img1._width - psizewc,
        offx2 = (ulongT)img2._width - psizewc,
        offy1 = (ulongT)img1._width*img1._height - (ulongT)psizeh*img1._width,
        offy2 = (ulongT)img2._width*img2._height - (ulongT)psizeh*img2._width;
      float ssd = 0;
      for (unsigned int k = 0; k<psized; ++k) {
        for (unsigned int j = 0; j<psizeh; ++j) {
          for (unsigned int i = 0; i<psizewc; ++i)
            ssd += cimg::sqr((Tfloat)*(p1++) - *(p2++));
          if (ssd>max_score) return max_score;
          p1+=offx1; p2+=offx2;
        }
        p1+=offy1; p2+=offy2;
      }
      return patch_penalization==0?ssd:cimg::sqr(std::sqrt(ssd) +
                                                 patch_penalization*psizewc*psizeh*psized*penalty(xc,yc,zc)/100);
    }

    static float _matchpatch(const CImg<T>& img1, const CImg<T>& img2, const CImg<floatT>& penalty,
                             const unsigned int psizew, const unsigned int psizeh, const unsigned int psizec,
                             const int x1, const int y1,
                             const int x2, const int y2,
                             const int xc, const int yc,
                             const float patch_penalization,
                             const bool allow_identity,
                             const float max_score) { // 2D version
      if (!allow_identity && cimg::hypot((float)x1 - x2,(float)y1 - y2)<patch_penalization)
        return cimg::type<float>::inf();
      const T *p1 = img1.data(x1*psizec,y1), *p2 = img2.data(x2*psizec,y2);
      const unsigned int psizewc = psizew*psizec;
      const ulongT
        offx1 = (ulongT)img1._width - psizewc,
        offx2 = (ulongT)img2._width - psizewc;
      float ssd = 0;
      for (unsigned int j = 0; j<psizeh; ++j) {
        for (unsigned int i = 0; i<psizewc; ++i)
          ssd += cimg::sqr((Tfloat)*(p1++) - *(p2++));
        if (ssd>max_score) return max_score;
        p1+=offx1; p2+=offx2;
      }
      return patch_penalization==0?ssd:cimg::sqr(std::sqrt(ssd) +
                                                 patch_penalization*psizewc*psizeh*penalty(xc,yc)/100);
    }

    //! Compute Euclidean distance function to a specified value.
    /**
        \param value Reference value.
        \param metric Type of metric. Can be <tt>{ 0=Chebyshev | 1=Manhattan | 2=Euclidean | 3=Squared-euclidean }</tt>.
        \note
        The distance transform implementation was submitted by A. Meijster, and implements
        the article 'W.H. Hesselink, A. Meijster, J.B.T.M. Roerdink,
                     "A general algorithm for computing distance transforms in linear time.",
                     In: Mathematical Morphology and its Applications to Image and Signal Processing,
                     J. Goutsias, L. Vincent, and D.S. Bloomberg (eds.), Kluwer, 2000, pp. 331-340.'
         The submitted code was then modified to fit CImg coding style and constraints.
    **/
    CImg<T>& distance(const T& value, const unsigned int metric=2) {
      if (is_empty()) return *this;
      if (cimg::type<Tint>::string()!=pixel_type()) // For datatype < int
        return CImg<Tint>(*this,false).distance((Tint)value,metric).
          cut((Tint)cimg::type<T>::min(),(Tint)cimg::type<T>::max()).move_to(*this);
      bool is_value = false;
      cimg_for(*this,ptr,T) *ptr = *ptr==value?is_value=true,(T)0:(T)std::max(0,99999999); // (avoid VC++ warning)
      if (!is_value) return fill(cimg::type<T>::max());
      switch (metric) {
      case 0 : return _distance_core(_distance_sep_cdt,_distance_dist_cdt); // Chebyshev
      case 1 : return _distance_core(_distance_sep_mdt,_distance_dist_mdt); // Manhattan
      case 3 : return _distance_core(_distance_sep_edt,_distance_dist_edt); // Squared Euclidean
      default : return _distance_core(_distance_sep_edt,_distance_dist_edt).sqrt(); // Euclidean
      }
      return *this;
    }

    //! Compute distance to a specified value \newinstance.
    CImg<Tfloat> get_distance(const T& value, const unsigned int metric=2) const {
      return CImg<Tfloat>(*this,false).distance((Tfloat)value,metric);
    }

    static longT _distance_sep_edt(const longT i, const longT u, const longT *const g) {
      return (u*u - i*i + g[u] - g[i])/(2*(u - i));
    }

    static longT _distance_dist_edt(const longT x, const longT i, const longT *const g) {
      return (x - i)*(x - i) + g[i];
    }

    static longT _distance_sep_mdt(const longT i, const longT u, const longT *const g) {
      return (u - i<=g[u] - g[i]?999999999:(g[u] - g[i] + u + i)/2);
    }

    static longT _distance_dist_mdt(const longT x, const longT i, const longT *const g) {
      return (x<i?i - x:x - i) + g[i];
    }

    static longT _distance_sep_cdt(const longT i, const longT u, const longT *const g) {
      const longT h = (i + u)/2;
      if (g[i]<=g[u]) { return h<i + g[u]?i + g[u]:h; }
      return h<u - g[i]?h:u - g[i];
    }

    static longT _distance_dist_cdt(const longT x, const longT i, const longT *const g) {
      const longT d = x<i?i - x:x - i;
      return d<g[i]?g[i]:d;
    }

    static void _distance_scan(const unsigned int len,
                               const longT *const g,
                               longT (*const sep)(const longT, const longT, const longT *const),
                               longT (*const f)(const longT, const longT, const longT *const),
                               longT *const s,
                               longT *const t,
                               longT *const dt) {
      longT q = s[0] = t[0] = 0;
      for (int u = 1; u<(int)len; ++u) { // Forward scan
        while ((q>=0) && f(t[q],s[q],g)>f(t[q],u,g)) { --q; }
        if (q<0) { q = 0; s[0] = u; }
        else { const longT w = 1 + sep(s[q], u, g); if (w<(longT)len) { ++q; s[q] = u; t[q] = w; }}
      }
      for (int u = (int)len - 1; u>=0; --u) { dt[u] = f(u,s[q],g); if (u==t[q]) --q; } // Backward scan
    }

    CImg<T>& _distance_core(longT (*const sep)(const longT, const longT, const longT *const),
                            longT (*const f)(const longT, const longT, const longT *const)) {
 // Check for g++ 4.9.X, as OpenMP seems to crash for this particular function. I have no clues why.
#define cimg_is_gcc49x (__GNUC__==4 && __GNUC_MINOR__==9)

      const ulongT wh = (ulongT)_width*_height;
#if cimg_use_openmp!=0 && !cimg_is_gcc49x
      cimg_pragma_openmp(parallel for cimg_openmp_if(_spectrum>=2))
#endif
      cimg_forC(*this,c) {
        CImg<longT> g(_width), dt(_width), s(_width), t(_width);
        CImg<T> img = get_shared_channel(c);
#if cimg_use_openmp!=0 && !cimg_is_gcc49x
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(2) cimg_openmp_if(_width>=(cimg_openmp_sizefactor)*512 &&
                                                                   _height*_depth>=16)
                           firstprivate(g,dt,s,t))
#endif
        cimg_forYZ(*this,y,z) { // Over X-direction
          cimg_forX(*this,x) g[x] = (longT)img(x,y,z,0,wh);
          _distance_scan(_width,g,sep,f,s,t,dt);
          cimg_forX(*this,x) img(x,y,z,0,wh) = (T)dt[x];
        }
        if (_height>1) {
          g.assign(_height); dt.assign(_height); s.assign(_height); t.assign(_height);
#if cimg_use_openmp!=0 && !cimg_is_gcc49x
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                             cimg_openmp_if(_height>=(cimg_openmp_sizefactor)*512 && _width*_depth>=16)
                             firstprivate(g,dt,s,t))
#endif
          cimg_forXZ(*this,x,z) { // Over Y-direction
            cimg_forY(*this,y) g[y] = (longT)img(x,y,z,0,wh);
            _distance_scan(_height,g,sep,f,s,t,dt);
            cimg_forY(*this,y) img(x,y,z,0,wh) = (T)dt[y];
          }
        }
        if (_depth>1) {
          g.assign(_depth); dt.assign(_depth); s.assign(_depth); t.assign(_depth);
#if cimg_use_openmp!=0 && !cimg_is_gcc49x
          cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                             cimg_openmp_if(_depth>=(cimg_openmp_sizefactor)*512 && _width*_height>=16)
                             firstprivate(g,dt,s,t))
#endif
          cimg_forXY(*this,x,y) { // Over Z-direction
            cimg_forZ(*this,z) g[z] = (longT)img(x,y,z,0,wh);
            _distance_scan(_depth,g,sep,f,s,t,dt);
            cimg_forZ(*this,z) img(x,y,z,0,wh) = (T)dt[z];
          }
        }
      }
      return *this;
    }

    //! Compute chamfer distance to a specified value, with a custom metric.
    /**
       \param value Reference value.
       \param metric_mask Metric mask.
       \note The algorithm code has been initially proposed by A. Meijster, and modified by D. Tschumperlé.
    **/
    template<typename t>
    CImg<T>& distance(const T& value, const CImg<t>& metric_mask) {
      if (is_empty()) return *this;
      bool is_value = false;
      cimg_for(*this,ptr,T) *ptr = *ptr==value?is_value=true,0:(T)999999999;
      if (!is_value) return fill(cimg::type<T>::max());
      const ulongT wh = (ulongT)_width*_height;
      cimg_pragma_openmp(parallel for cimg_openmp_if(_spectrum>=2))
      cimg_forC(*this,c) {
        CImg<T> img = get_shared_channel(c);
        cimg_pragma_openmp(parallel for cimg_openmp_collapse(3)
                           cimg_openmp_if(_width*_height*_depth>=(cimg_openmp_sizefactor)*1024))
        cimg_forXYZ(metric_mask,dx,dy,dz) {
          const t weight = metric_mask(dx,dy,dz);
          if (weight) {
            for (int z = dz, nz = 0; z<depth(); ++z,++nz) { // Forward scan
              for (int y = dy , ny = 0; y<height(); ++y,++ny) {
                for (int x = dx, nx = 0; x<width(); ++x,++nx) {
                  const T dd = img(nx,ny,nz,0,wh) + weight;
                  if (dd<img(x,y,z,0,wh)) img(x,y,z,0,wh) = dd;
                }
              }
            }
            for (int z = depth() - 1 - dz, nz = depth() - 1; z>=0; --z,--nz) { // Backward scan
              for (int y = height() - 1 - dy, ny = height() - 1; y>=0; --y,--ny) {
                for (int x = width() - 1 - dx, nx = width() - 1; x>=0; --x,--nx) {
                  const T dd = img(nx,ny,nz,0,wh) + weight;
                  if (dd<img(x,y,z,0,wh)) img(x,y,z,0,wh) = dd;
                }
              }
            }
          }
        }
      }
      return *this;
    }

    //! Compute chamfer distance to a specified value, with a custom metric \newinstance.
    template<typename t>
    CImg<Tfloat> get_distance(const T& value, const CImg<t>& metric_mask) const {
      return CImg<Tfloat>(*this,false).distance(value,metric_mask);
    }

    //! Compute distance to a specified value, according to a custom metric (use dijkstra algorithm).
    /**
       \param value Reference value.
       \param metric Field of distance potentials.
       \param is_high_connectivity Indicates whether the algorithm uses low or high connectivity.
       \param[out] return_path An image containing the nodes of the minimal path.
     **/
    template<typename t, typename to>
    CImg<T>& distance_dijkstra(const T& value, const CImg<t>& metric, const bool is_high_connectivity,
                               CImg<to>& return_path) {
      return get_distance_dijkstra(value,metric,is_high_connectivity,return_path).move_to(*this);
    }

    //! Compute distance map to a specified value, according to a custom metric (use dijkstra algorithm) \newinstance.
    template<typename t, typename to>
    CImg<typename cimg::superset<t,long>::type>
    get_distance_dijkstra(const T& value, const CImg<t>& metric, const bool is_high_connectivity,
                          CImg<to>& return_path) const {
      if (is_empty()) return return_path.assign();
      if (!is_sameXYZ(metric))
        throw CImgArgumentException(_cimg_instance
                                    "distance_dijkstra(): image instance and metric map (%u,%u,%u,%u) "
                                    "have incompatible dimensions.",
                                    cimg_instance,
                                    metric._width,metric._height,metric._depth,metric._spectrum);
      typedef typename cimg::superset<t,long>::type td; // Type used for computing cumulative distances
      CImg<td> result(_width,_height,_depth,_spectrum), Q;
      CImg<boolT> is_queued(_width,_height,_depth,1);
      if (return_path) return_path.assign(_width,_height,_depth,_spectrum);

      cimg_forC(*this,c) {
        const CImg<T> img = get_shared_channel(c);
        const CImg<t> met = metric.get_shared_channel(c%metric._spectrum);
        CImg<td> res = result.get_shared_channel(c);
        CImg<to> path = return_path?return_path.get_shared_channel(c):CImg<to>();
        unsigned int sizeQ = 0;

        // Detect initial seeds.
        is_queued.fill(0);
        cimg_forXYZ(img,x,y,z) if (img(x,y,z)==value) {
          Q._priority_queue_insert(is_queued,sizeQ,0,x,y,z);
          res(x,y,z) = 0;
          if (path) path(x,y,z) = (to)0;
        }

        // Start distance propagation.
        while (sizeQ) {

          // Get and remove point with minimal potential from the queue.
          const int x = (int)Q(0,1), y = (int)Q(0,2), z = (int)Q(0,3);
          const td P = (td)-Q(0,0);
          Q._priority_queue_remove(sizeQ);

          // Update neighbors.
          td npot = 0;
          if (x - 1>=0 && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x - 1,y,z) + P),x - 1,y,z)) {
            res(x - 1,y,z) = npot; if (path) path(x - 1,y,z) = (to)2;
          }
          if (x + 1<width() && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x + 1,y,z) + P),x + 1,y,z)) {
            res(x + 1,y,z) = npot; if (path) path(x + 1,y,z) = (to)1;
          }
          if (y - 1>=0 && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x,y - 1,z) + P),x,y - 1,z)) {
            res(x,y - 1,z) = npot; if (path) path(x,y - 1,z) = (to)8;
          }
          if (y + 1<height() && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x,y + 1,z) + P),x,y + 1,z)) {
            res(x,y + 1,z) = npot; if (path) path(x,y + 1,z) = (to)4;
          }
          if (z - 1>=0 && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x,y,z - 1) + P),x,y,z - 1)) {
            res(x,y,z - 1) = npot; if (path) path(x,y,z - 1) = (to)32;
          }
          if (z + 1<depth() && Q._priority_queue_insert(is_queued,sizeQ,-(npot=met(x,y,z + 1) + P),x,y,z + 1)) {
            res(x,y,z + 1) = npot; if (path) path(x,y,z + 1) = (to)16;
          }

          if (is_high_connectivity) {
            const float sqrt2 = std::sqrt(2.f), sqrt3 = std::sqrt(3.f);

            // Diagonal neighbors on slice z.
            if (x - 1>=0 && y - 1>=0 &&
                Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x - 1,y - 1,z) + P)),x - 1,y - 1,z)) {
              res(x - 1,y - 1,z) = npot; if (path) path(x - 1,y - 1,z) = (to)10;
            }
            if (x + 1<width() && y - 1>=0 &&
                Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x + 1,y - 1,z) + P)),x + 1,y - 1,z)) {
              res(x + 1,y - 1,z) = npot; if (path) path(x + 1,y - 1,z) = (to)9;
            }
            if (x - 1>=0 && y + 1<height() &&
                Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x - 1,y + 1,z) + P)),x - 1,y + 1,z)) {
              res(x - 1,y + 1,z) = npot; if (path) path(x - 1,y + 1,z) = (to)6;
            }
            if (x + 1<width() && y + 1<height() &&
                Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x + 1,y + 1,z) + P)),x + 1,y + 1,z)) {
              res(x + 1,y + 1,z) = npot; if (path) path(x + 1,y + 1,z) = (to)5;
            }

            if (z - 1>=0) { // Diagonal neighbors on slice z - 1
              if (x - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x - 1,y,z - 1) + P)),x - 1,y,z - 1)) {
                res(x - 1,y,z - 1) = npot; if (path) path(x - 1,y,z - 1) = (to)34;
              }
              if (x + 1<width() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x + 1,y,z - 1) + P)),x + 1,y,z - 1)) {
                res(x + 1,y,z - 1) = npot; if (path) path(x + 1,y,z - 1) = (to)33;
              }
              if (y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x,y - 1,z - 1) + P)),x,y - 1,z - 1)) {
                res(x,y - 1,z - 1) = npot; if (path) path(x,y - 1,z - 1) = (to)40;
              }
              if (y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x,y + 1,z - 1) + P)),x,y + 1,z - 1)) {
                res(x,y + 1,z - 1) = npot; if (path) path(x,y + 1,z - 1) = (to)36;
              }
              if (x - 1>=0 && y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x - 1,y - 1,z - 1) + P)),
                                           x - 1,y - 1,z - 1)) {
                res(x - 1,y - 1,z - 1) = npot; if (path) path(x - 1,y - 1,z - 1) = (to)42;
              }
              if (x + 1<width() && y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x + 1,y - 1,z - 1) + P)),
                                           x + 1,y - 1,z - 1)) {
                res(x + 1,y - 1,z - 1) = npot; if (path) path(x + 1,y - 1,z - 1) = (to)41;
              }
              if (x - 1>=0 && y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x - 1,y + 1,z - 1) + P)),
                                           x - 1,y + 1,z - 1)) {
                res(x - 1,y + 1,z - 1) = npot; if (path) path(x - 1,y + 1,z - 1) = (to)38;
              }
              if (x + 1<width() && y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x + 1,y + 1,z - 1) + P)),
                                           x + 1,y + 1,z - 1)) {
                res(x + 1,y + 1,z - 1) = npot; if (path) path(x + 1,y + 1,z - 1) = (to)37;
              }
            }

            if (z + 1<depth()) { // Diagonal neighbors on slice z + 1
              if (x - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x - 1,y,z + 1) + P)),x - 1,y,z + 1)) {
                res(x - 1,y,z + 1) = npot; if (path) path(x - 1,y,z + 1) = (to)18;
              }
              if (x + 1<width() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x + 1,y,z + 1) + P)),x + 1,y,z + 1)) {
                res(x + 1,y,z + 1) = npot; if (path) path(x + 1,y,z + 1) = (to)17;
              }
              if (y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x,y - 1,z + 1) + P)),x,y - 1,z + 1)) {
                res(x,y - 1,z + 1) = npot; if (path) path(x,y - 1,z + 1) = (to)24;
              }
              if (y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt2*met(x,y + 1,z + 1) + P)),x,y + 1,z + 1)) {
                res(x,y + 1,z + 1) = npot; if (path) path(x,y + 1,z + 1) = (to)20;
              }
              if (x - 1>=0 && y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x - 1,y - 1,z + 1) + P)),
                                           x - 1,y - 1,z + 1)) {
                res(x - 1,y - 1,z + 1) = npot; if (path) path(x - 1,y - 1,z + 1) = (to)26;
              }
              if (x + 1<width() && y - 1>=0 &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x + 1,y - 1,z + 1) + P)),
                                           x + 1,y - 1,z + 1)) {
                res(x + 1,y - 1,z + 1) = npot; if (path) path(x + 1,y - 1,z + 1) = (to)25;
              }
              if (x - 1>=0 && y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x - 1,y + 1,z + 1) + P)),
                                           x - 1,y + 1,z + 1)) {
                res(x - 1,y + 1,z + 1) = npot; if (path) path(x - 1,y + 1,z + 1) = (to)22;
              }
              if (x + 1<width() && y + 1<height() &&
                  Q._priority_queue_insert(is_queued,sizeQ,-(npot=(td)(sqrt3*met(x + 1,y + 1,z + 1) + P)),
                                           x + 1,y + 1,z + 1)) {
                res(x + 1,y + 1,z + 1) = npot; if (path) path(x + 1,y + 1,z + 1) = (to)21;
              }
            }
          }
        }
      }
      return result;
    }

    //! Compute distance map to a specified value, according to a custom metric (use dijkstra algorithm) \overload.
    template<typename t>
    CImg<T>& distance_dijkstra(const T& value, const CImg<t>& metric,
                               const bool is_high_connectivity=false) {
      return get_distance_dijkstra(value,metric,is_high_connectivity).move_to(*this);
    }

    //! Compute distance map to a specified value, according to a custom metric (use dijkstra algorithm). \newinstance.
    template<typename t>
    CImg<Tfloat> get_distance_dijkstra(const T& value, const CImg<t>& metric,
                                       const bool is_high_connectivity=false) const {
      CImg<T> return_path;
      return get_distance_dijkstra(value,metric,is_high_connectivity,return_path);
    }

    //! Compute distance map to one source point, according to a custom metric (use fast marching algorithm).
    /**
       \param value Reference value.
       \param metric Field of distance potentials.
     **/
    template<typename t>
    CImg<T>& distance_eikonal(const T& value, const CImg<t>& metric) {
      return get_distance_eikonal(value,metric).move_to(*this);
    }

    //! Compute distance map to one source point, according to a custom metric (use fast marching algorithm).
    template<typename t>
    CImg<Tfloat> get_distance_eikonal(const T& value, const CImg<t>& metric) const {
      if (is_empty()) return *this;
      if (!is_sameXYZ(metric))
        throw CImgArgumentException(_cimg_instance
                                    "distance_eikonal(): image instance and metric map (%u,%u,%u,%u) have "
                                    "incompatible dimensions.",
                                    cimg_instance,
                                    metric._width,metric._height,metric._depth,metric._spectrum);
      CImg<Tfloat> result(_width,_height,_depth,_spectrum,cimg::type<Tfloat>::max()), Q;
      cimg_pragma_openmp(parallel for cimg_openmp_if(_spectrum>=2))
      cimg_forC(*this,c) {
        CImg<charT> state(_width,_height,_depth); // -1=far away, 0=narrow, 1=frozen
        const CImg<T> img = get_shared_channel(c);
        const CImg<t> met = metric.get_shared_channel(c%metric._spectrum);
        CImg<Tfloat> res = result.get_shared_channel(c);
        unsigned int sizeQ = 0;
        state.fill(-1);

        // Detect initial seeds.
        Tfloat *ptr1 = res._data; char *ptr2 = state._data;
        cimg_for(img,ptr0,T) { if (*ptr0==value) { *ptr1 = 0; *ptr2 = 1; } ++ptr1; ++ptr2; }

        // Initialize seeds neighbors.
        ptr2 = state._data;
        cimg_forXYZ(img,x,y,z) if (*(ptr2++)==1) {
          if (x - 1>=0 && state(x - 1,y,z)==-1) {
            const Tfloat dist = res(x - 1,y,z) = __distance_eikonal(res,met(x - 1,y,z),x - 1,y,z);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x - 1,y,z);
          }
          if (x + 1<width() && state(x + 1,y,z)==-1) {
            const Tfloat dist = res(x + 1,y,z) = __distance_eikonal(res,met(x + 1,y,z),x + 1,y,z);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x + 1,y,z);
          }
          if (y - 1>=0 && state(x,y - 1,z)==-1) {
            const Tfloat dist = res(x,y - 1,z) = __distance_eikonal(res,met(x,y - 1,z),x,y - 1,z);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y - 1,z);
          }
          if (y + 1<height() && state(x,y + 1,z)==-1) {
            const Tfloat dist = res(x,y + 1,z) = __distance_eikonal(res,met(x,y + 1,z),x,y + 1,z);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y + 1,z);
          }
          if (z - 1>=0 && state(x,y,z - 1)==-1) {
            const Tfloat dist = res(x,y,z - 1) = __distance_eikonal(res,met(x,y,z - 1),x,y,z - 1);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y,z - 1);
          }
          if (z + 1<depth() && state(x,y,z + 1)==-1) {
            const Tfloat dist = res(x,y,z + 1) = __distance_eikonal(res,met(x,y,z + 1),x,y,z + 1);
            Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y,z + 1);
          }
        }

        // Propagate front.
        while (sizeQ) {
          int x = -1, y = -1, z = -1;
          while (sizeQ && x<0) {
            x = (int)Q(0,1); y = (int)Q(0,2); z = (int)Q(0,3);
            Q._priority_queue_remove(sizeQ);
            if (state(x,y,z)==1) x = -1; else state(x,y,z) = 1;
          }
          if (x>=0) {
            if (x - 1>=0 && state(x - 1,y,z)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x - 1,y,z),x - 1,y,z);
              if (dist<res(x - 1,y,z)) {
                res(x - 1,y,z) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x - 1,y,z);
              }
            }
            if (x + 1<width() && state(x + 1,y,z)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x + 1,y,z),x + 1,y,z);
              if (dist<res(x + 1,y,z)) {
                res(x + 1,y,z) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x + 1,y,z);
              }
            }
            if (y - 1>=0 && state(x,y - 1,z)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x,y - 1,z),x,y - 1,z);
              if (dist<res(x,y - 1,z)) {
                res(x,y - 1,z) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y - 1,z);
              }
            }
            if (y + 1<height() && state(x,y + 1,z)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x,y + 1,z),x,y + 1,z);
              if (dist<res(x,y + 1,z)) {
                res(x,y + 1,z) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y + 1,z);
              }
            }
            if (z - 1>=0 && state(x,y,z - 1)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x,y,z - 1),x,y,z - 1);
              if (dist<res(x,y,z - 1)) {
                res(x,y,z - 1) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y,z - 1);
              }
            }
            if (z + 1<depth() && state(x,y,z + 1)!=1) {
              const Tfloat dist = __distance_eikonal(res,met(x,y,z + 1),x,y,z + 1);
              if (dist<res(x,y,z + 1)) {
                res(x,y,z + 1) = dist; Q._eik_priority_queue_insert(state,sizeQ,-dist,x,y,z + 1);
              }
            }
          }
        }
      }
      return result;
    }

    // Locally solve eikonal equation.
    Tfloat __distance_eikonal(const CImg<Tfloat>& res, const Tfloat P,
                              const int x=0, const int y=0, const int z=0) const {
      const Tfloat M = (Tfloat)cimg::type<T>::max();
      T T1 = (T)std::min(x - 1>=0?res(x - 1,y,z):M,x + 1<width()?res(x + 1,y,z):M);
      Tfloat root = 0;
      if (_depth>1) { // 3D
        T
          T2 = (T)std::min(y - 1>=0?res(x,y - 1,z):M,y + 1<height()?res(x,y + 1,z):M),
          T3 = (T)std::min(z - 1>=0?res(x,y,z - 1):M,z + 1<depth()?res(x,y,z + 1):M);
        if (T1>T2) cimg::swap(T1,T2);
        if (T2>T3) cimg::swap(T2,T3);
        if (T1>T2) cimg::swap(T1,T2);
        if (P<=0) return (Tfloat)T1;
        if (T3<M && ___distance_eikonal(3,-2*(T1 + T2 + T3),T1*T1 + T2*T2 + T3*T3 - P*P,root))
          return std::max((Tfloat)T3,root);
        if (T2<M && ___distance_eikonal(2,-2*(T1 + T2),T1*T1 + T2*T2 - P*P,root))
          return std::max((Tfloat)T2,root);
        return P + T1;
      } else if (_height>1) { // 2D
        T T2 = (T)std::min(y - 1>=0?res(x,y - 1,z):M,y + 1<height()?res(x,y + 1,z):M);
        if (T1>T2) cimg::swap(T1,T2);
        if (P<=0) return (Tfloat)T1;
        if (T2<M && ___distance_eikonal(2,-2*(T1 + T2),T1*T1 + T2*T2 - P*P,root))
          return std::max((Tfloat)T2,root);
        return P + T1;
      } else { // 1D
        if (P<=0) return (Tfloat)T1;
        return P + T1;
      }
      return 0;
    }

    // Find max root of a 2nd-order polynomial.
    static bool ___distance_eikonal(const Tfloat a, const Tfloat b, const Tfloat c, Tfloat &root) {
      const Tfloat delta = b*b - 4*a*c;
      if (delta<0) return false;
      root = 0.5f*(-b + std::sqrt(delta))/a;
      return true;
    }

    // Insert new point in heap.
    template<typename t>
    void _eik_priority_queue_insert(CImg<charT>& state, unsigned int& siz, const t value,
                                    const unsigned int x, const unsigned int y, const unsigned int z) {
      if (state(x,y,z)>0) return;
      state(x,y,z) = 0;
      if (++siz>=_width) { if (!is_empty()) resize(_width*2,4,1,1,0); else assign(64,4); }
      (*this)(siz - 1,0) = (T)value; (*this)(siz - 1,1) = (T)x; (*this)(siz - 1,2) = (T)y; (*this)(siz - 1,3) = (T)z;
      for (unsigned int pos = siz - 1, par = 0; pos && value>(t)(*this)(par=(pos + 1)/2 - 1,0); pos = par) {
        cimg::swap((*this)(pos,0),(*this)(par,0)); cimg::swap((*this)(pos,1),(*this)(par,1));
        cimg::swap((*this)(pos,2),(*this)(par,2)); cimg::swap((*this)(pos,3),(*this)(par,3));
      }
    }

    //! Compute distance function to 0-valued isophotes, using the Eikonal PDE.
    /**
       \param nb_iterations Number of PDE iterations.
       \param band_size Size of the narrow band.
       \param time_step Time step of the PDE iterations.
    **/
    CImg<T>& distance_eikonal(const unsigned int nb_iterations, const float band_size=0, const float time_step=0.5f) {
      if (is_empty()) return *this;
      CImg<Tfloat> velocity(*this,false);
      for (unsigned int iteration = 0; iteration<nb_iterations; ++iteration) {
        Tfloat *ptrd = velocity._data, veloc_max = 0;
        if (_depth>1) { // 3D
          CImg_3x3x3(I,Tfloat);
          cimg_forC(*this,c) cimg_for3x3x3(*this,x,y,z,c,I,Tfloat) if (band_size<=0 || cimg::abs(Iccc)<band_size) {
            const Tfloat
              gx = (Incc - Ipcc)/2,
              gy = (Icnc - Icpc)/2,
              gz = (Iccn - Iccp)/2,
              sgn = -cimg::sign(Iccc),
              ix = gx*sgn>0?(Incc - Iccc):(Iccc - Ipcc),
              iy = gy*sgn>0?(Icnc - Iccc):(Iccc - Icpc),
              iz = gz*sgn>0?(Iccn - Iccc):(Iccc - Iccp),
              ng = 1e-5f + cimg::hypot(gx,gy,gz),
              ngx = gx/ng,
              ngy = gy/ng,
              ngz = gz/ng,
              veloc = sgn*(ngx*ix + ngy*iy + ngz*iz - 1);
            *(ptrd++) = veloc;
            if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
          } else *(ptrd++) = 0;
        } else { // 2D version
          CImg_3x3(I,Tfloat);
          cimg_forC(*this,c) cimg_for3x3(*this,x,y,0,c,I,Tfloat) if (band_size<=0 || cimg::abs(Icc)<band_size) {
            const Tfloat
              gx = (Inc - Ipc)/2,
              gy = (Icn - Icp)/2,
              sgn = -cimg::sign(Icc),
              ix = gx*sgn>0?(Inc - Icc):(Icc - Ipc),
              iy = gy*sgn>0?(Icn - Icc):(Icc - Icp),
              ng = std::max((Tfloat)1e-5,cimg::hypot(gx,gy)),
              ngx = gx/ng,
              ngy = gy/ng,
              veloc = sgn*(ngx*ix + ngy*iy - 1);
            *(ptrd++) = veloc;
            if (veloc>veloc_max) veloc_max = veloc; else if (-veloc>veloc_max) veloc_max = -veloc;
          } else *(ptrd++) = 0;
        }
        if (veloc_max>0) *this+=(velocity*=time_step/veloc_max);
      }
      return *this;
    }

    //! Compute distance function to 0-valued isophotes, using the Eikonal PDE \newinstance.
    CImg<Tfloat> get_distance_eikonal(const unsigned int nb_iterations, const float band_size=0,
                                      const float time_step=0.5f) const {
      return CImg<Tfloat>(*this,false).distance_eikonal(nb_iterations,band_size,time_step);
    }

    //! Compute Haar multiscale wavelet transform.
    /**
       \param axis Axis considered for the transform.
       \param invert Set inverse of direct transform.
       \param nb_scales Number of scales used for the transform.
    **/
    CImg<T>& haar(const char axis, const bool invert=false, const unsigned int nb_scales=1) {
      return get_haar(axis,invert,nb_scales).move_to(*this);
    }

    //! Compute Haar multiscale wavelet transform \newinstance.
    CImg<Tfloat> get_haar(const char axis, const bool invert=false, const unsigned int nb_scales=1) const {
      if (is_empty() || !nb_scales) return +*this;
      CImg<Tfloat> res;
      const Tfloat sqrt2 = std::sqrt(2.f);
      if (nb_scales==1) {
        switch (cimg::lowercase(axis)) { // Single scale transform
        case 'x' : {
          const unsigned int w = _width/2;
          if (w) {
            if ((w%2) && w!=1)
              throw CImgInstanceException(_cimg_instance
                                          "haar(): Sub-image width %u is not even.",
                                          cimg_instance,
                                          w);

            res.assign(_width,_height,_depth,_spectrum);
            if (invert) cimg_forYZC(*this,y,z,c) { // Inverse transform along X
              for (unsigned int x = 0, xw = w, x2 = 0; x<w; ++x, ++xw) {
                const Tfloat val0 = (Tfloat)(*this)(x,y,z,c), val1 = (Tfloat)(*this)(xw,y,z,c);
                res(x2++,y,z,c) = (val0 - val1)/sqrt2;
                res(x2++,y,z,c) = (val0 + val1)/sqrt2;
              }
            } else cimg_forYZC(*this,y,z,c) { // Direct transform along X
              for (unsigned int x = 0, xw = w, x2 = 0; x<w; ++x, ++xw) {
                const Tfloat val0 = (Tfloat)(*this)(x2++,y,z,c), val1 = (Tfloat)(*this)(x2++,y,z,c);
                res(x,y,z,c) = (val0 + val1)/sqrt2;
                res(xw,y,z,c) = (val1 - val0)/sqrt2;
              }
            }
          } else return *this;
        } break;
        case 'y' : {
          const unsigned int h = _height/2;
          if (h) {
            if ((h%2) && h!=1)
              throw CImgInstanceException(_cimg_instance
                                          "haar(): Sub-image height %u is not even.",
                                          cimg_instance,
                                          h);

            res.assign(_width,_height,_depth,_spectrum);
            if (invert) cimg_forXZC(*this,x,z,c) { // Inverse transform along Y
              for (unsigned int y = 0, yh = h, y2 = 0; y<h; ++y, ++yh) {
                const Tfloat val0 = (Tfloat)(*this)(x,y,z,c), val1 = (Tfloat)(*this)(x,yh,z,c);
                res(x,y2++,z,c) = (val0 - val1)/sqrt2;
                res(x,y2++,z,c) = (val0 + val1)/sqrt2;
              }
            } else cimg_forXZC(*this,x,z,c) {
              for (unsigned int y = 0, yh = h, y2 = 0; y<h; ++y, ++yh) { // Direct transform along Y
                const Tfloat val0 = (Tfloat)(*this)(x,y2++,z,c), val1 = (Tfloat)(*this)(x,y2++,z,c);
                res(x,y,z,c)  = (val0 + val1)/sqrt2;
                res(x,yh,z,c) = (val1 - val0)/sqrt2;
              }
            }
          } else return *this;
        } break;
        case 'z' : {
          const unsigned int d = _depth/2;
          if (d) {
            if ((d%2) && d!=1)
              throw CImgInstanceException(_cimg_instance
                                          "haar(): Sub-image depth %u is not even.",
                                          cimg_instance,
                                          d);

            res.assign(_width,_height,_depth,_spectrum);
            if (invert) cimg_forXYC(*this,x,y,c) { // Inverse transform along Z
              for (unsigned int z = 0, zd = d, z2 = 0; z<d; ++z, ++zd) {
                const Tfloat val0 = (Tfloat)(*this)(x,y,z,c), val1 = (Tfloat)(*this)(x,y,zd,c);
                res(x,y,z2++,c) = (val0 - val1)/sqrt2;
                res(x,y,z2++,c) = (val0 + val1)/sqrt2;
              }
            } else cimg_forXYC(*this,x,y,c) {
              for (unsigned int z = 0, zd = d, z2 = 0; z<d; ++z, ++zd) { // Direct transform along Z
                const Tfloat val0 = (Tfloat)(*this)(x,y,z2++,c), val1 = (Tfloat)(*this)(x,y,z2++,c);
                res(x,y,z,c)  = (val0 + val1)/sqrt2;
                res(x,y,zd,c) = (val1 - val0)/sqrt2;
              }
            }
          } else return *this;
        } break;
        default :
          throw CImgArgumentException(_cimg_instance
                                      "haar(): Invalid specified axis '%c' "
                                      "(should be { x | y | z }).",
                                      cimg_instance,
                                      axis);
        }
      } else { // Multi-scale version
        if (invert) {
          res.assign(*this,false);
          switch (cimg::lowercase(axis)) {
          case 'x' : {
            unsigned int w = _width;
            for (unsigned int s = 1; w && s<nb_scales; ++s) w/=2;
            for (w = w?w:1; w<=_width; w*=2) res.draw_image(res.get_crop(0,w - 1).get_haar('x',true,1));
          } break;
          case 'y' : {
            unsigned int h = _width;
            for (unsigned int s = 1; h && s<nb_scales; ++s) h/=2;
            for (h = h?h:1; h<=_height; h*=2) res.draw_image(res.get_crop(0,0,_width - 1,h - 1).get_haar('y',true,1));
          } break;
          case 'z' : {
            unsigned int d = _depth;
            for (unsigned int s = 1; d && s<nb_scales; ++s) d/=2;
            for (d = d?d:1; d<=_depth; d*=2)
              res.draw_image(res.get_crop(0,0,0,_width - 1,_height - 1,d - 1).get_haar('z',true,1));
          } break;
          default :
            throw CImgArgumentException(_cimg_instance
                                        "haar(): Invalid specified axis '%c' "
                                        "(should be { x | y | z }).",
                                        cimg_instance,
                                        axis);
          }
        } else { // Direct transform
          res = get_haar(axis,false,1);
          switch (cimg::lowercase(axis)) {
          case 'x' : {
            for (unsigned int s = 1, w = _width/2; w && s<nb_scales; ++s, w/=2)
              res.draw_image(res.get_crop(0,w - 1).get_haar('x',false,1));
          } break;
          case 'y' : {
            for (unsigned int s = 1, h = _height/2; h && s<nb_scales; ++s, h/=2)
              res.draw_image(res.get_crop(0,0,_width - 1,h - 1).get_haar('y',false,1));
          } break;
          case 'z' : {
            for (unsigned int s = 1, d = _depth/2; d && s<nb_scales; ++s, d/=2)
              res.draw_image(res.get_crop(0,0,0,_width - 1,_height - 1,d - 1).get_haar('z',false,1));
          } break;
          default :
            throw CImgArgumentException(_cimg_instance
                                        "haar(): Invalid specified axis '%c' "
                                        "(should be { x | y | z }).",
                                        cimg_instance,
                                        axis);
          }
        }
      }
      return res;
    }

    //! Compute Haar multiscale wavelet transform \overload.
    /**
       \param invert Set inverse of direct transform.
       \param nb_scales Number of scales used for the transform.
    **/
    CImg<T>& haar(const bool invert=false, const unsigned int nb_scales=1) {
      return get_haar(invert,nb_scales).move_to(*this);
    }

    //! Compute Haar multiscale wavelet transform \newinstance.
    CImg<Tfloat> get_haar(const bool invert=false, const unsigned int nb_scales=1) const {
      CImg<Tfloat> res;
      if (nb_scales==1) { // Single scale transform
        if (_width>1) get_haar('x',invert,1).move_to(res);
        if (_height>1) { if (res) res.haar('y',invert,1); else get_haar('y',invert,1).move_to(res); }
        if (_depth>1) { if (res) res.haar('z',invert,1); else get_haar('z',invert,1).move_to(res); }
        if (res) return res;
      } else { // Multi-scale transform
        if (invert) { // Inverse transform
          res.assign(*this,false);
          if (_width>1) {
            if (_height>1) {
              if (_depth>1) {
                unsigned int w = _width, h = _height, d = _depth;
                for (unsigned int s = 1; w && h && d && s<nb_scales; ++s) { w/=2; h/=2; d/=2; }
                for (w = w?w:1, h = h?h:1, d = d?d:1; w<=_width && h<=_height && d<=_depth; w*=2, h*=2, d*=2)
                  res.draw_image(res.get_crop(0,0,0,w - 1,h - 1,d - 1).get_haar(true,1));
              } else {
                unsigned int w = _width, h = _height;
                for (unsigned int s = 1; w && h && s<nb_scales; ++s) { w/=2; h/=2; }
                for (w = w?w:1, h = h?h:1; w<=_width && h<=_height; w*=2, h*=2)
                  res.draw_image(res.get_crop(0,0,0,w - 1,h - 1,0).get_haar(true,1));
              }
            } else {
              if (_depth>1) {
                unsigned int w = _width, d = _depth;
                for (unsigned int s = 1; w && d && s<nb_scales; ++s) { w/=2; d/=2; }
                for (w = w?w:1, d = d?d:1; w<=_width && d<=_depth; w*=2, d*=2)
                  res.draw_image(res.get_crop(0,0,0,w - 1,0,d - 1).get_haar(true,1));
              } else {
                unsigned int w = _width;
                for (unsigned int s = 1; w && s<nb_scales; ++s) w/=2;
                for (w = w?w:1; w<=_width; w*=2)
                  res.draw_image(res.get_crop(0,0,0,w - 1,0,0).get_haar(true,1));
              }
            }
          } else {
            if (_height>1) {
              if (_depth>1) {
                unsigned int h = _height, d = _depth;
                for (unsigned int s = 1; h && d && s<nb_scales; ++s) { h/=2; d/=2; }
                for (h = h?h:1, d = d?d:1; h<=_height && d<=_depth; h*=2, d*=2)
                  res.draw_image(res.get_crop(0,0,0,0,h - 1,d - 1).get_haar(true,1));
              } else {
                unsigned int h = _height;
                for (unsigned int s = 1; h && s<nb_scales; ++s) h/=2;
                for (h = h?h:1; h<=_height; h*=2)
                  res.draw_image(res.get_crop(0,0,0,0,h - 1,0).get_haar(true,1));
              }
            } else {
              if (_depth>1) {
                unsigned int d = _depth;
                for (unsigned int s = 1; d && s<nb_scales; ++s) d/=2;
                for (d = d?d:1; d<=_depth; d*=2)
                  res.draw_image(res.get_crop(0,0,0,0,0,d - 1).get_haar(true,1));
              } else return *this;
            }
          }
        } else { // Direct transform
          res = get_haar(false,1);
          if (_width>1) {
            if (_height>1) {
              if (_depth>1)
                for (unsigned int s = 1, w = _width/2, h = _height/2, d = _depth/2; w && h && d && s<nb_scales;
                     ++s, w/=2, h/=2, d/=2)
                  res.draw_image(res.get_crop(0,0,0,w - 1,h - 1,d - 1).haar(false,1));
              else for (unsigned int s = 1, w = _width/2, h = _height/2; w && h && s<nb_scales; ++s, w/=2, h/=2)
                     res.draw_image(res.get_crop(0,0,0,w - 1,h - 1,0).haar(false,1));
            } else {
              if (_depth>1) for (unsigned int s = 1, w = _width/2, d = _depth/2; w && d && s<nb_scales; ++s, w/=2, d/=2)
                              res.draw_image(res.get_crop(0,0,0,w - 1,0,d - 1).haar(false,1));
              else for (unsigned int s = 1, w = _width/2; w && s<nb_scales; ++s, w/=2)
                     res.draw_image(res.get_crop(0,0,0,w - 1,0,0).haar(false,1));
            }
          } else {
            if (_height>1) {
              if (_depth>1)
                for (unsigned int s = 1, h = _height/2, d = _depth/2; h && d && s<nb_scales; ++s, h/=2, d/=2)
                  res.draw_image(res.get_crop(0,0,0,0,h - 1,d - 1).haar(false,1));
              else for (unsigned int s = 1, h = _height/2; h && s<nb_scales; ++s, h/=2)
                     res.draw_image(res.get_crop(0,0,0,0,h - 1,0).haar(false,1));
            } else {
              if (_depth>1) for (unsigned int s = 1, d = _depth/2; d && s<nb_scales; ++s, d/=2)
                              res.draw_image(res.get_crop(0,0,0,0,0,d - 1).haar(false,1));
              else return *this;
            }
          }
        }
        return res;
      }
      return *this;
    }

    //! Compute 1D Fast Fourier Transform, along a specified axis.
    /**
       \param axis Axis along which the FFT is computed.
       \param is_inverse Indicates whether the forward (\c false) or inverse (\c true) FFT is computed.
    **/
    CImgList<Tfloat> get_FFT(const char axis, const bool is_inverse=false) const {
      CImgList<Tfloat> res(*this,CImg<Tfloat>());
      CImg<Tfloat>::FFT(res[0],res[1],axis,is_inverse);
      return res;
    }

    //! Compute n-D Fast Fourier Transform.
    /*
      \param is_inverse Indicates whether the forward (\c false) or inverse (\c true) FFT is computed.
    **/
    CImgList<Tfloat> get_FFT(const bool is_inverse=false) const {
      CImgList<Tfloat> res(*this,CImg<Tfloat>());
      CImg<Tfloat>::FFT(res[0],res[1],is_inverse);
      return res;
    }

    //! Compute 1D Fast Fourier Transform, along a specified axis.
    /**
       \param[in,out] real Real part of the pixel values.
       \param[in,out] imag Imaginary part of the pixel values.
       \param axis Axis along which the FFT is computed.
       \param is_inverse Indicates whether the forward (\c false) or inverse (\c true) FFT is computed.
       \param nb_threads Set the maximum number of threads used for FFT computation.
    **/
    static void FFT(CImg<T>& real, CImg<T>& imag, const char axis, const bool is_inverse=false,
                    const unsigned int nb_threads=0) {
      if (!real)
        throw CImgInstanceException("CImg<%s>::FFT(): Specified real part is empty.",
                                    pixel_type());
      if (!imag) imag.assign(real._width,real._height,real._depth,real._spectrum,(T)0);
      if (!real.is_sameXYZC(imag))
        throw CImgInstanceException("CImg<%s>::FFT(): Specified real part (%u,%u,%u,%u,%p) and "
                                    "imaginary part (%u,%u,%u,%u,%p) have different dimensions.",
                                    pixel_type(),
                                    real._width,real._height,real._depth,real._spectrum,real._data,
                                    imag._width,imag._height,imag._depth,imag._spectrum,imag._data);
      const char _axis = cimg::lowercase(axis);
      if (_axis!='x' && _axis!='y' && _axis!='z')
        throw CImgArgumentException("CImgList<%s>::FFT(): Invalid specified axis '%c' for real and imaginary parts "
                                    "(%u,%u,%u,%u) "
                                    "(should be { x | y | z }).",
                                    pixel_type(),axis,
                                    real._width,real._height,real._depth,real._spectrum);
      cimg::unused(nb_threads);
#ifdef cimg_use_fftw3
      cimg::mutex(12);
#ifndef cimg_use_fftw3_singlethread
      fftw_plan_with_nthreads(nb_threads?nb_threads:cimg::nb_cpus());
#endif
      fftw_complex *data_in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*real._width*real._height*real._depth);
      if (!data_in)
        throw CImgInstanceException("CImgList<%s>::FFT(): Failed to allocate memory (%s) "
                                    "for computing FFT of image (%u,%u,%u,%u) along the X-axis.",
                                    pixel_type(),
                                    cimg::strbuffersize(sizeof(fftw_complex)*real._width*real._height*real._depth),
                                    real._width,real._height,real._depth,real._spectrum);
      double *const ptrf = (double*)data_in;
      fftw_plan data_plan =
        _axis=='x'?fftw_plan_many_dft(1,(int*)&real._width,real.height()*real.depth(),
                                      data_in,0,1,real.width(),
                                      data_in,0,1,real.width(),
                                      is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE):
        _axis=='y'?fftw_plan_many_dft(1,(int*)&real._height,real.width()*real.depth(),
                                      data_in,0,1,real.height(),
                                      data_in,0,1,real.height(),
                                      is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE):
        fftw_plan_many_dft(1,(int*)&real._depth,real.width()*real.height(),
                           data_in,0,1,real.depth(),
                           data_in,0,1,real.depth(),
                           is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE);
      cimg_forC(real,c) {
        CImg<T> realc = real.get_shared_channel(c), imagc = imag.get_shared_channel(c);
        switch (_axis) {
        case 'x' :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = realc.offset(x,y,z),
              j = 2*(x + (ulongT)y*realc._width + (ulongT)z*realc._width*realc._height);
            ptrf[j] = (double)realc[i];
            ptrf[j + 1] = (double)imagc[i];
          }
          break;
        case 'y' :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = realc.offset(x,y,z),
              j = 2*(y + (ulongT)x*realc._height + (ulongT)z*realc._width*realc._height);
            ptrf[j] = (double)realc[i];
            ptrf[j + 1] = (double)imagc[i];
          }
          break;
        default :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = realc.offset(x,y,z),
              j = 2*(z + (ulongT)x*realc._depth + (ulongT)y*realc._width*realc._depth);
            ptrf[j] = (double)realc[i];
            ptrf[j + 1] = (double)imagc[i];
          }
        }

        fftw_execute(data_plan);

        const double a = is_inverse?1.0/(_axis=='x'?real.width():_axis=='y'?real.height():real.depth()):1.0;
        switch (_axis) {
        case 'x' :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = 2*(x + (ulongT)y*realc._width + (ulongT)z*realc._width*realc._height),
              j = realc.offset(x,y,z);
            realc[j] = (T)(a*ptrf[i]);
            imagc[j] = (T)(a*ptrf[i + 1]);
          }
          break;
        case 'y' :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = 2*(y + (ulongT)x*realc._height + (ulongT)z*realc._width*realc._height),
              j = realc.offset(x,y,z);
            realc[j] = (T)(a*ptrf[i]);
            imagc[j] = (T)(a*ptrf[i + 1]);
          }
          break;
        default :
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_forXYZ(realc,x,y,z) {
            const ulongT
              i = 2*(z + (ulongT)x*realc._depth + (ulongT)y*realc._width*realc._depth),
              j = realc.offset(x,y,z);
            realc[j] = (T)(a*ptrf[i]);
            imagc[j] = (T)(a*ptrf[i + 1]);
          }
        }
      }

      fftw_destroy_plan(data_plan);
      fftw_free(data_in);
#ifndef cimg_use_fftw3_singlethread
      fftw_cleanup_threads();
#endif
      cimg::mutex(12,0);
#else
      switch (_axis) {
      case 'x' : { // Fourier along X, using built-in functions
        const unsigned int N = real._width, N2 = N>>1;
        if (((N - 1)&N) && N!=1)
          throw CImgInstanceException("CImgList<%s>::FFT(): Specified real and imaginary parts (%u,%u,%u,%u) "
                                      "have non 2^N dimension along the X-axis.",
                                      pixel_type(),
                                      real._width,real._height,real._depth,real._spectrum);

        for (unsigned int i = 0, j = 0; i<N2; ++i) {
          if (j>i) cimg_forYZC(real,y,z,c) {
              cimg::swap(real(i,y,z,c),real(j,y,z,c));
              cimg::swap(imag(i,y,z,c),imag(j,y,z,c));
              if (j<N2) {
                const unsigned int ri = N - 1 - i, rj = N - 1 - j;
                cimg::swap(real(ri,y,z,c),real(rj,y,z,c));
                cimg::swap(imag(ri,y,z,c),imag(rj,y,z,c));
              }
            }
          for (unsigned int m = N, n = N2; (j+=n)>=m; j-=m, m = n, n>>=1) {}
        }
        for (unsigned int delta = 2; delta<=N; delta<<=1) {
          const unsigned int delta2 = delta>>1;
          for (unsigned int i = 0; i<N; i+=delta) {
            float wr = 1, wi = 0;
            const float
              angle = (float)((is_inverse?+1:-1)*2*cimg::PI/delta),
              ca = (float)std::cos(angle),
              sa = (float)std::sin(angle);
            for (unsigned int k = 0; k<delta2; ++k) {
              const unsigned int j = i + k, nj = j + delta2;
              cimg_forYZC(real,y,z,c) {
                T &ir = real(j,y,z,c), &ii = imag(j,y,z,c), &nir = real(nj,y,z,c), &nii = imag(nj,y,z,c);
                const float tmpr = (float)(wr*nir - wi*nii), tmpi = (float)(wr*nii + wi*nir);
                nir = (T)(ir - tmpr);
                nii = (T)(ii - tmpi);
                ir+=(T)tmpr;
                ii+=(T)tmpi;
              }
              const float nwr = wr*ca-wi*sa;
              wi = wi*ca + wr*sa;
              wr = nwr;
            }
          }
          if (delta==N) break;
        }
        if (is_inverse) { real/=N; imag/=N; }
      } break;
      case 'y' : { // Fourier along Y, using built-in functions
        const unsigned int N = real._height, N2 = N>>1;
        if (((N - 1)&N) && N!=1)
          throw CImgInstanceException("CImgList<%s>::FFT(): Specified real and imaginary parts (%u,%u,%u,%u) "
                                      "have non 2^N dimension along the Y-axis.",
                                      pixel_type(),
                                      real._width,real._height,real._depth,real._spectrum);

        for (unsigned int i = 0, j = 0; i<N2; ++i) {
          if (j>i) cimg_forXZC(real,x,z,c) {
              cimg::swap(real(x,i,z,c),real(x,j,z,c));
              cimg::swap(imag(x,i,z,c),imag(x,j,z,c));
              if (j<N2) {
                const unsigned int ri = N - 1 - i, rj = N - 1 - j;
                cimg::swap(real(x,ri,z,c),real(x,rj,z,c));
                cimg::swap(imag(x,ri,z,c),imag(x,rj,z,c));
              }
            }
          for (unsigned int m = N, n = N2; (j+=n)>=m; j-=m, m = n, n>>=1) {}
        }
        for (unsigned int delta = 2; delta<=N; delta<<=1) {
          const unsigned int delta2 = (delta>>1);
          for (unsigned int i = 0; i<N; i+=delta) {
            float wr = 1, wi = 0;
            const float
              angle = (float)((is_inverse?+1:-1)*2*cimg::PI/delta),
              ca = (float)std::cos(angle),
              sa = (float)std::sin(angle);
            for (unsigned int k = 0; k<delta2; ++k) {
              const unsigned int j = i + k, nj = j + delta2;
              cimg_forXZC(real,x,z,c) {
                T &ir = real(x,j,z,c), &ii = imag(x,j,z,c), &nir = real(x,nj,z,c), &nii = imag(x,nj,z,c);
                const float tmpr = (float)(wr*nir - wi*nii), tmpi = (float)(wr*nii + wi*nir);
                nir = (T)(ir - tmpr);
                nii = (T)(ii - tmpi);
                ir+=(T)tmpr;
                ii+=(T)tmpi;
              }
              const float nwr = wr*ca-wi*sa;
              wi = wi*ca + wr*sa;
              wr = nwr;
            }
          }
          if (delta==N) break;
        }
        if (is_inverse) { real/=N; imag/=N; }
      } break;
      default : { // Fourier along Z, using built-in functions
        const unsigned int N = real._depth, N2 = N>>1;
        if (((N - 1)&N) && N!=1)
          throw CImgInstanceException("CImgList<%s>::FFT(): Specified real and imaginary parts (%u,%u,%u,%u) "
                                      "have non 2^N dimension along the Z-axis.",
                                      pixel_type(),
                                      real._width,real._height,real._depth,real._spectrum);

        for (unsigned int i = 0, j = 0; i<N2; ++i) {
          if (j>i) cimg_forXYC(real,x,y,c) {
              cimg::swap(real(x,y,i,c),real(x,y,j,c));
              cimg::swap(imag(x,y,i,c),imag(x,y,j,c));
              if (j<N2) {
                const unsigned int ri = N - 1 - i, rj = N - 1 - j;
                cimg::swap(real(x,y,ri,c),real(x,y,rj,c));
                cimg::swap(imag(x,y,ri,c),imag(x,y,rj,c));
              }
            }
          for (unsigned int m = N, n = N2; (j+=n)>=m; j-=m, m = n, n>>=1) {}
        }
        for (unsigned int delta = 2; delta<=N; delta<<=1) {
          const unsigned int delta2 = (delta>>1);
          for (unsigned int i = 0; i<N; i+=delta) {
            float wr = 1, wi = 0;
            const float
              angle = (float)((is_inverse?+1:-1)*2*cimg::PI/delta),
              ca = (float)std::cos(angle),
              sa = (float)std::sin(angle);
            for (unsigned int k = 0; k<delta2; ++k) {
              const unsigned int j = i + k, nj = j + delta2;
              cimg_forXYC(real,x,y,c) {
                T &ir = real(x,y,j,c), &ii = imag(x,y,j,c), &nir = real(x,y,nj,c), &nii = imag(x,y,nj,c);
                const float tmpr = (float)(wr*nir - wi*nii), tmpi = (float)(wr*nii + wi*nir);
                nir = (T)(ir - tmpr);
                nii = (T)(ii - tmpi);
                ir+=(T)tmpr;
                ii+=(T)tmpi;
              }
              const float nwr = wr*ca-wi*sa;
              wi = wi*ca + wr*sa;
              wr = nwr;
            }
          }
          if (delta==N) break;
        }
        if (is_inverse) { real/=N; imag/=N; }
      } break;
      }
#endif
    }

    //! Compute n-D Fast Fourier Transform.
    /**
       \param[in,out] real Real part of the pixel values.
       \param[in,out] imag Imaginary part of the pixel values.
       \param is_inverse Indicates whether the forward (\c false) or inverse (\c true) FFT is computed.
       \param nb_threads Number of parallel threads used for the computation.
         Use \c 0 to set this to the number of available cpus.
    **/
    static void FFT(CImg<T>& real, CImg<T>& imag, const bool is_inverse=false,
                    const unsigned int nb_threads=0) {
      if (!real)
        throw CImgInstanceException("CImgList<%s>::FFT(): Empty specified real part.",
                                    pixel_type());
      if (!imag) imag.assign(real._width,real._height,real._depth,real._spectrum,(T)0);
      if (!real.is_sameXYZC(imag))
        throw CImgInstanceException("CImgList<%s>::FFT(): Specified real part (%u,%u,%u,%u,%p) and "
                                    "imaginary part (%u,%u,%u,%u,%p) have different dimensions.",
                                    pixel_type(),
                                    real._width,real._height,real._depth,real._spectrum,real._data,
                                    imag._width,imag._height,imag._depth,imag._spectrum,imag._data);
      cimg::unused(nb_threads);
#ifdef cimg_use_fftw3
      cimg::mutex(12);
#ifndef cimg_use_fftw3_singlethread
      fftw_plan_with_nthreads(nb_threads?nb_threads:cimg::nb_cpus());
#endif
      fftw_complex *data_in = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*real._width*real._height*real._depth);
      if (!data_in)
        throw CImgInstanceException("CImgList<%s>::FFT(): Failed to allocate memory (%s) "
                                    "for computing FFT of image (%u,%u,%u,%u).",
                                    pixel_type(),
                                    cimg::strbuffersize(sizeof(fftw_complex)*real._width*
                                                        real._height*real._depth*real._spectrum),
                                    real._width,real._height,real._depth,real._spectrum);
      double *const ptrf = (double*)data_in;
      fftw_plan data_plan =
        real._depth>1?fftw_plan_dft_3d(real._depth,real._height,real._width,data_in,data_in,
                                       is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE):
        real._height>1?fftw_plan_dft_2d(real._height,real._width,data_in,data_in,
                                        is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE):
        fftw_plan_dft_1d(real._width,data_in,data_in,
                         is_inverse?FFTW_BACKWARD:FFTW_FORWARD,FFTW_ESTIMATE);
      cimg_forC(real,c) {
        CImg<T> realc = real.get_shared_channel(c), imagc = imag.get_shared_channel(c);
        cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
        cimg_rofoff(realc,i) { const ulongT i2 = 2*i; ptrf[i2] = (double)realc[i]; ptrf[i2 + 1] = (double)imagc[i]; }
        fftw_execute(data_plan);
        if (is_inverse) {
          const double a = 1.0/(real.width()*real.height()*real.depth());
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_rofoff(realc,i) { const ulongT i2 = 2*i; realc[i] = (T)(a*ptrf[i2]); imagc[i] = (T)(a*ptrf[i2 + 1]); }
        } else
          cimg_pragma_openmp(parallel for cimg_openmp_if_size(real.width()*real.height()*real.depth(),125000))
          cimg_rofoff(realc,i) { const ulongT i2 = 2*i; realc[i] = (T)ptrf[i2]; imagc[i] = (T)ptrf[i2 + 1]; }
      }
      fftw_destroy_plan(data_plan);
      fftw_free(data_in);
#ifndef cimg_use_fftw3_singlethread
      fftw_cleanup_threads();
#endif
      cimg::mutex(12,0);
#else
      if (real._depth>1) FFT(real,imag,'z',is_inverse);
      if (real._height>1) FFT(real,imag,'y',is_inverse);
      if (real._width>1) FFT(real,imag,'x',is_inverse);
#endif
    }

    //@}
    //-------------------------------------
    //
    //! \name 3D Objects Management
    //@{
    //-------------------------------------

    //! Rotate 3D object's vertices.
    /**
       \param x X-coordinate of the rotation axis, or first quaternion coordinate.
       \param y Y-coordinate of the rotation axis, or second quaternion coordinate.
       \param z Z-coordinate of the rotation axis, or second quaternion coordinate.
       \param w Angle of the rotation axis (in degree), or fourth quaternion coordinate.
       \param is_quaternion Specifies whether the four arguments denote a set of { axis + angle } or
                            a quaternion (x,y,z,w).
    **/
    CImg<T>& rotate_object3d(const float x, const float y, const float z, const float w,
                             const bool is_quaternion=false) {
      return get_rotate_object3d(x,y,z,w,is_quaternion).move_to(*this);
    }

    CImg<Tfloat> get_rotate_object3d(const float x, const float y, const float z, const float w,
                                     const bool is_quaternion=false) const {
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "rotate_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);
      return CImg<Tfloat>::rotation_matrix(x,y,z,w,is_quaternion)**this;
    }

    //! Shift 3D object's vertices.
    /**
       \param tx X-coordinate of the 3D displacement vector.
       \param ty Y-coordinate of the 3D displacement vector.
       \param tz Z-coordinate of the 3D displacement vector.
    **/
    CImg<T>& shift_object3d(const float tx, const float ty=0, const float tz=0) {
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "shift_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);

      get_shared_row(0)+=tx; get_shared_row(1)+=ty; get_shared_row(2)+=tz;
      return *this;
    }

    //! Shift 3D object's vertices \newinstance.
    CImg<Tfloat> get_shift_object3d(const float tx, const float ty=0, const float tz=0) const {
      return CImg<Tfloat>(*this,false).shift_object3d(tx,ty,tz);
    }

    //! Shift 3D object's vertices, so that it becomes centered.
    /**
       \note The object center is computed as its barycenter.
    **/
    CImg<T>& shift_object3d() {
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "shift_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);

      CImg<T> xcoords = get_shared_row(0), ycoords = get_shared_row(1), zcoords = get_shared_row(2);
      float
        xm, xM = (float)xcoords.max_min(xm),
        ym, yM = (float)ycoords.max_min(ym),
        zm, zM = (float)zcoords.max_min(zm);
      xcoords-=(xm + xM)/2; ycoords-=(ym + yM)/2; zcoords-=(zm + zM)/2;
      return *this;
    }

    //! Shift 3D object's vertices, so that it becomes centered \newinstance.
    CImg<Tfloat> get_shift_object3d() const {
      return CImg<Tfloat>(*this,false).shift_object3d();
    }

    //! Resize 3D object.
    /**
       \param sx Width of the 3D object's bounding box.
       \param sy Height of the 3D object's bounding box.
       \param sz Depth of the 3D object's bounding box.
    **/
    CImg<T>& resize_object3d(const float sx, const float sy=-100, const float sz=-100) {
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "resize_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);

      CImg<T> xcoords = get_shared_row(0), ycoords = get_shared_row(1), zcoords = get_shared_row(2);
      float
        xm, xM = (float)xcoords.max_min(xm),
        ym, yM = (float)ycoords.max_min(ym),
        zm, zM = (float)zcoords.max_min(zm);
      if (xm<xM) { if (sx>0) xcoords*=sx/(xM-xm); else xcoords*=-sx/100; }
      if (ym<yM) { if (sy>0) ycoords*=sy/(yM-ym); else ycoords*=-sy/100; }
      if (zm<zM) { if (sz>0) zcoords*=sz/(zM-zm); else zcoords*=-sz/100; }
      return *this;
    }

    //! Resize 3D object \newinstance.
    CImg<Tfloat> get_resize_object3d(const float sx, const float sy=-100, const float sz=-100) const {
      return CImg<Tfloat>(*this,false).resize_object3d(sx,sy,sz);
    }

    //! Resize 3D object to unit size.
    CImg<T> resize_object3d() {
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "resize_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);

      CImg<T> xcoords = get_shared_row(0), ycoords = get_shared_row(1), zcoords = get_shared_row(2);
      float
        xm, xM = (float)xcoords.max_min(xm),
        ym, yM = (float)ycoords.max_min(ym),
        zm, zM = (float)zcoords.max_min(zm);
      const float dx = xM - xm, dy = yM - ym, dz = zM - zm, dmax = cimg::max(dx,dy,dz);
      if (dmax>0) { xcoords/=dmax; ycoords/=dmax; zcoords/=dmax; }
      return *this;
    }

    //! Resize 3D object to unit size \newinstance.
    CImg<Tfloat> get_resize_object3d() const {
      return CImg<Tfloat>(*this,false).resize_object3d();
    }

    //! Merge two 3D objects.
    /**
       \param[in,out] primitives Primitives data of the current 3D object.
       \param obj_vertices Vertices data of the additional 3D object.
       \param obj_primitives Primitives data of the additional 3D object.
    **/
    template<typename tf, typename tp, typename tff>
    CImg<T>& append_object3d(CImgList<tf>& primitives, const CImg<tp>& obj_vertices,
                             const CImgList<tff>& obj_primitives) {
      if (!obj_vertices || !obj_primitives) return *this;
      if (obj_vertices._height!=3 || obj_vertices._depth>1 || obj_vertices._spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "append_object3d(): Specified vertex image (%u,%u,%u,%u,%p) is not a "
                                    "set of 3D vertices.",
                                    cimg_instance,
                                    obj_vertices._width,obj_vertices._height,
                                    obj_vertices._depth,obj_vertices._spectrum,obj_vertices._data);

      if (is_empty()) { primitives.assign(obj_primitives); return assign(obj_vertices); }
      if (_height!=3 || _depth>1 || _spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "append_object3d(): Instance is not a set of 3D vertices.",
                                    cimg_instance);

      const unsigned int P = _width;
      append(obj_vertices,'x');
      const unsigned int N = primitives._width;
      primitives.insert(obj_primitives);
      for (unsigned int i = N; i<primitives._width; ++i) {
        CImg<tf> &p = primitives[i];
        switch (p.size()) {
        case 1 : p[0]+=P; break; // Point
        case 5 : p[0]+=P; p[1]+=P; break; // Sphere
        case 2 : case 6 : p[0]+=P; p[1]+=P; break; // Segment
        case 3 : case 9 : p[0]+=P; p[1]+=P; p[2]+=P; break; // Triangle
        case 4 : case 12 : p[0]+=P; p[1]+=P; p[2]+=P; p[3]+=P; break; // Rectangle
        }
      }
      return *this;
    }

    //! Texturize the primitives of a 3D object.
    /**
       \param[in,out] primitives Primitives data of the 3D object.
       \param[in,out] colors Colors data of the 3D object.
       \param texture Texture image to map to 3D object.
       \param coords Texture-mapping coordinates.
    **/
    template<typename tp, typename tc, typename tt, typename tx>
    const CImg<T>& texturize_object3d(CImgList<tp>& primitives, CImgList<tc>& colors,
                                      const CImg<tt>& texture, const CImg<tx>& coords=CImg<tx>::const_empty()) const {
      if (is_empty()) return *this;
      if (_height!=3)
        throw CImgInstanceException(_cimg_instance
                                    "texturize_object3d(): image instance is not a set of 3D points.",
                                    cimg_instance);
      if (coords && (coords._width!=_width || coords._height!=2))
        throw CImgArgumentException(_cimg_instance
                                    "texturize_object3d(): Invalid specified texture coordinates (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    coords._width,coords._height,coords._depth,coords._spectrum,coords._data);
      CImg<intT> _coords;
      if (!coords) { // If no texture coordinates specified, do a default XY-projection
        _coords.assign(_width,2);
        float
          xmin, xmax = (float)get_shared_row(0).max_min(xmin),
          ymin, ymax = (float)get_shared_row(1).max_min(ymin),
          dx = xmax>xmin?xmax-xmin:1,
          dy = ymax>ymin?ymax-ymin:1;
        cimg_forX(*this,p) {
          _coords(p,0) = (int)(((*this)(p,0) - xmin)*texture._width/dx);
          _coords(p,1) = (int)(((*this)(p,1) - ymin)*texture._height/dy);
        }
      } else _coords = coords;

      int texture_ind = -1;
      cimglist_for(primitives,l) {
        CImg<tp> &p = primitives[l];
        const unsigned int siz = p.size();
        switch (siz) {
        case 1 : { // Point
          const unsigned int i0 = (unsigned int)p[0];
          const int x0 = _coords(i0,0), y0 = _coords(i0,1);
          texture.get_vector_at(x0<=0?0:x0>=texture.width()?texture.width() - 1:x0,
                                y0<=0?0:y0>=texture.height()?texture.height() - 1:y0).move_to(colors[l]);
        } break;
        case 2 : case 6 : { // Segment
          const unsigned int i0 = (unsigned int)p[0], i1 = (unsigned int)p[1];
          const int
            x0 = _coords(i0,0), y0 = _coords(i0,1),
            x1 = _coords(i1,0), y1 = _coords(i1,1);
          if (texture_ind<0) colors[texture_ind=l].assign(texture,false);
          else colors[l].assign(colors[texture_ind],true);
          CImg<tp>::vector(i0,i1,x0,y0,x1,y1).move_to(p);
        } break;
        case 3 : case 9 : { // Triangle
          const unsigned int i0 = (unsigned int)p[0], i1 = (unsigned int)p[1], i2 = (unsigned int)p[2];
          const int
            x0 = _coords(i0,0), y0 = _coords(i0,1),
            x1 = _coords(i1,0), y1 = _coords(i1,1),
            x2 = _coords(i2,0), y2 = _coords(i2,1);
          if (texture_ind<0) colors[texture_ind=l].assign(texture,false);
          else colors[l].assign(colors[texture_ind],true);
          CImg<tp>::vector(i0,i1,i2,x0,y0,x1,y1,x2,y2).move_to(p);
        } break;
        case 4 : case 12 : { // Quadrangle
          const unsigned int
            i0 = (unsigned int)p[0], i1 = (unsigned int)p[1], i2 = (unsigned int)p[2], i3 = (unsigned int)p[3];
          const int
            x0 = _coords(i0,0), y0 = _coords(i0,1),
            x1 = _coords(i1,0), y1 = _coords(i1,1),
            x2 = _coords(i2,0), y2 = _coords(i2,1),
            x3 = _coords(i3,0), y3 = _coords(i3,1);
          if (texture_ind<0) colors[texture_ind=l].assign(texture,false);
          else colors[l].assign(colors[texture_ind],true);
          CImg<tp>::vector(i0,i1,i2,i3,x0,y0,x1,y1,x2,y2,x3,y3).move_to(p);
        } break;
        }
      }
      return *this;
    }

    //! Generate a 3D elevation map from the instance image, as a 3D object.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param[out] colors The returned list of the 3D object colors.
       \param elevation The input elevation map.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       const CImg<float> img("reference.jpg");
       CImgList<unsigned int> faces3d;
       CImgList<unsigned char> colors3d;
       const CImg<float> points3d = img.get_elevation3d(faces3d,colors3d,img.get_norm()*0.2);
       CImg<unsigned char>().display_object3d("Elevation3d",points3d,faces3d,colors3d);
       \endcode
       \image html ref_elevation3d.jpg
    **/
    template<typename tf, typename tc, typename te>
    CImg<floatT> get_elevation3d(CImgList<tf>& primitives, CImgList<tc>& colors, const CImg<te>& elevation) const {
      if (!is_sameXY(elevation) || elevation._depth>1 || elevation._spectrum>1)
        throw CImgArgumentException(_cimg_instance
                                    "get_elevation3d(): Instance and specified elevation (%u,%u,%u,%u,%p) "
                                    "have incompatible dimensions.",
                                    cimg_instance,
                                    elevation._width,elevation._height,elevation._depth,
                                    elevation._spectrum,elevation._data);
      if (is_empty()) return *this;
      float m, M = (float)max_min(m);
      if (M==m) ++M;
      const unsigned int size_x1 = _width - 1, size_y1 = _height - 1;
      colors.assign(size_x1*size_y1,1,3);
      unsigned int off = 0;
      for (unsigned int y = 0; y<size_y1; ++y)
        for (unsigned int x = 0; x<size_x1; ++x) {
          const unsigned char
            r = (unsigned char)(((*this)(x,y,0) - m)*255/(M - m)),
            g = (unsigned char)(_spectrum>1?((*this)(x,y,1) - m)*255/(M - m):r),
            b = (unsigned char)(_spectrum>2?((*this)(x,y,2) - m)*255/(M - m):_spectrum>1?0:r);
          CImg<tc>& color = colors[off++];
          color[0] = (tc)r;
          color[1] = (tc)g;
          color[2] = (tc)b;
        }
      const typename CImg<te>::_functor2d_int func(elevation);
      return elevation3d(primitives,func,0,0,_width - 1.f,_height - 1.f,_width,_height);
    }

    //! Generate the 3D projection planes of the image instance.
    /**
       \param[out] primitives Primitives data of the returned 3D object.
       \param[out] colors Colors data of the returned 3D object.
       \param x0 X-coordinate of the projection point.
       \param y0 Y-coordinate of the projection point.
       \param z0 Z-coordinate of the projection point.
       \param normalize_colors Indicates whether the created textures have normalized colors.
    **/
    template<typename tf, typename tc>
    CImg<floatT> get_projections3d(CImgList<tf>& primitives, CImgList<tc>& colors,
                                   const unsigned int x0, const unsigned int y0, const unsigned int z0,
                                   const bool normalize_colors=false) const {
      float m = 0, M = 0, delta = 1;
      if (normalize_colors) { m = (float)min_max(M); delta = 255/(m==M?1:M-m); }
      const unsigned int
        _x0 = (x0>=_width)?_width - 1:x0,
        _y0 = (y0>=_height)?_height - 1:y0,
        _z0 = (z0>=_depth)?_depth - 1:z0;
      CImg<tc> img_xy, img_xz, img_yz;
      if (normalize_colors) {
        ((get_crop(0,0,_z0,0,_width - 1,_height - 1,_z0,_spectrum - 1)-=m)*=delta).move_to(img_xy);
        ((get_crop(0,_y0,0,0,_width - 1,_y0,_depth - 1,_spectrum - 1)-=m)*=delta).resize(_width,_depth,1,-100,-1).
          move_to(img_xz);
        ((get_crop(_x0,0,0,0,_x0,_height - 1,_depth - 1,_spectrum - 1)-=m)*=delta).resize(_height,_depth,1,-100,-1).
          move_to(img_yz);
      } else {
        get_crop(0,0,_z0,0,_width - 1,_height - 1,_z0,_spectrum - 1).move_to(img_xy);
        get_crop(0,_y0,0,0,_width - 1,_y0,_depth - 1,_spectrum - 1).resize(_width,_depth,1,-100,-1).move_to(img_xz);
        get_crop(_x0,0,0,0,_x0,_height - 1,_depth - 1,_spectrum - 1).resize(_height,_depth,1,-100,-1).move_to(img_yz);
      }
      CImg<floatT> points(12,3,1,1,
                          0,_width - 1,_width - 1,0,   0,_width - 1,_width - 1,0, _x0,_x0,_x0,_x0,
                          0,0,_height - 1,_height - 1, _y0,_y0,_y0,_y0,       0,_height - 1,_height - 1,0,
                          _z0,_z0,_z0,_z0,         0,0,_depth - 1,_depth - 1, 0,0,_depth - 1,_depth - 1);
      primitives.assign();
      CImg<tf>::vector(0,1,2,3,0,0,img_xy._width - 1,0,img_xy._width - 1,img_xy._height - 1,0,img_xy._height - 1).
        move_to(primitives);
      CImg<tf>::vector(4,5,6,7,0,0,img_xz._width - 1,0,img_xz._width - 1,img_xz._height - 1,0,img_xz._height - 1).
        move_to(primitives);
      CImg<tf>::vector(8,9,10,11,0,0,img_yz._width - 1,0,img_yz._width - 1,img_yz._height - 1,0,img_yz._height - 1).
        move_to(primitives);
      colors.assign();
      img_xy.move_to(colors);
      img_xz.move_to(colors);
      img_yz.move_to(colors);
      return points;
    }

    //! Generate an isoline from the current image instance, as a 3D object.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param isovalue The scalar value used as the threshold for extraction.
       \param size_x The number of subdivisions along the X-axis.
       \param size_y The number of subdivisions along the Y-axis.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       const CImg<float> img("reference.jpg");
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = img.get_isoline3d(faces3d,100);
       CImg<unsigned char>().display_object3d("Isoline3d",points3d,faces3d,colors3d);
       \endcode
       \image html ref_isoline3d.jpg
    **/
    template<typename tf>
    CImg<floatT> get_isoline3d(CImgList<tf>& primitives, const float isovalue,
                               const int size_x=-100, const int size_y=-100) const {
      if (_spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "get_isoline3d(): Instance is not a scalar image.",
                                    cimg_instance);
      if (_depth>1)
        throw CImgInstanceException(_cimg_instance
                                    "get_isoline3d(): Instance is not a 2D image.",
                                    cimg_instance);
      primitives.assign();
      if (is_empty()) return *this;
      CImg<floatT> vertices;
      if ((size_x==-100 && size_y==-100) || (size_x==width() && size_y==height())) {
        const _functor2d_int func(*this);
        vertices = isoline3d(primitives,func,isovalue,0,0,width() - 1.f,height() - 1.f,width(),height());
      } else {
        const _functor2d_float func(*this);
        vertices = isoline3d(primitives,func,isovalue,0,0,width() - 1.f,height() - 1.f,size_x,size_y);
      }
      return vertices;
    }

    //! Compute isolines of a function, as a 3D object.
    /**
       \param[out] primitives Primitives data of the resulting 3D object.
       \param func Elevation functor. Must have <tt>operator()(x,y)</tt> defined.
       \param isovalue The scalar value used as the threshold for extraction.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param size_x Resolution of the function along the X-axis.
       \param size_y Resolution of the function along the Y-axis.
       \note Uses the marching squares algorithm for extracting the isolines.
     **/
    template<typename tf, typename tfunc>
    static CImg<floatT> isoline3d(CImgList<tf>& primitives, const tfunc& func, const float isovalue,
                                  const float x0, const float y0, const float x1, const float y1,
                                  const int size_x=256, const int size_y=256) {
      CImgList<floatT> vertices;
      primitives.assign();
      typename CImg<floatT>::_functor_isoline3d add_vertex(vertices);
      typename CImg<tf>::_functor_isoline3d add_segment(primitives);
      isoline3d(add_vertex,add_segment,func,isovalue,x0,y0,x1,y1,size_x,size_y);
      return vertices>'x';
    }

    //! Compute isolines of a function, as a 3D object.
    /**
       \param[out] add_vertex : Functor with operator()(x,y,z) defined for adding a new vertex.
       \param[out] add_segment : Functor with operator()(i,j) defined for adding a new segment.
       \param func Elevation function. Is of type <tt>float (*func)(const float x,const float y)</tt>.
       \param isovalue The scalar value used as the threshold for extraction.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param size_x Resolution of the function along the X-axis.
       \param size_y Resolution of the function along the Y-axis.
       \note Uses the marching squares algorithm for extracting the isolines.
     **/
    template<typename tv, typename tf, typename tfunc>
    static void isoline3d(tv& add_vertex, tf& add_segment, const tfunc& func, const float isovalue,
                          const float x0, const float y0, const float x1, const float y1,
                          const int size_x, const int size_y) {
      static const unsigned int edges[16] = { 0x0, 0x9, 0x3, 0xa, 0x6, 0xf, 0x5, 0xc, 0xc,
                                              0x5, 0xf, 0x6, 0xa, 0x3, 0x9, 0x0 };
      static const int segments[16][4] = { { -1,-1,-1,-1 }, { 0,3,-1,-1 }, { 0,1,-1,-1 }, { 1,3,-1,-1 },
                                           { 1,2,-1,-1 },   { 0,1,2,3 },   { 0,2,-1,-1 }, { 2,3,-1,-1 },
                                           { 2,3,-1,-1 },   { 0,2,-1,-1},  { 0,3,1,2 },   { 1,2,-1,-1 },
                                           { 1,3,-1,-1 },   { 0,1,-1,-1},  { 0,3,-1,-1},  { -1,-1,-1,-1 } };
      const unsigned int
        _nx = (unsigned int)(size_x>=0?size_x:cimg::round((x1-x0)*-size_x/100 + 1)),
        _ny = (unsigned int)(size_y>=0?size_y:cimg::round((y1-y0)*-size_y/100 + 1)),
        nx = _nx?_nx:1,
        ny = _ny?_ny:1,
        nxm1 = nx - 1,
        nym1 = ny - 1;

      if (!nxm1 || !nym1) return;
      const float dx = (x1 - x0)/nxm1, dy = (y1 - y0)/nym1;
      CImg<intT> indices1(nx,1,1,2,-1), indices2(nx,1,1,2);
      CImg<floatT> values1(nx), values2(nx);
      float X = x0, Y = y0, nX = X + dx, nY = Y + dy;
      int nb_vertices = 0;

      // Fill first line with values.
      cimg_forX(values1,x) { values1(x) = (float)func(X,Y); X+=dx; }

      // Run the marching squares algorithm.
      for (unsigned int yi = 0, nyi = 1; yi<nym1; ++yi, ++nyi, Y=nY, nY+=dy) {
        X = x0; nX = X + dx;
        indices2.fill(-1);
        values2(0) = (float)func(X,nY);
        for (unsigned int xi = 0, nxi = 1; xi<nxm1; ++xi, ++nxi, X=nX, nX+=dx) {

          // Determine square configuration.
          const float
            val0 = values1(xi),
            val1 = values1(nxi),
            val2 = values2(nxi) = (float)func(nX,nY),
            val3 = values2(xi);
          const unsigned int
            configuration = (val0<isovalue?1U:0U) | (val1<isovalue?2U:0U) |
            (val2<isovalue?4U:0U) | (val3<isovalue?8U:0U),
            edge = edges[configuration];

          // Compute intersection vertices.
          if (edge) {
            if ((edge&1) && indices1(xi,0)<0) {
              const float Xi = X + (isovalue-val0)*dx/(val1-val0);
              indices1(xi,0) = nb_vertices++;
              add_vertex(Xi,Y,0.f);
            }
            if ((edge&2) && indices1(nxi,1)<0) {
              const float Yi = Y + (isovalue-val1)*dy/(val2-val1);
              indices1(nxi,1) = nb_vertices++;
              add_vertex(nX,Yi,0.f);
            }
            if ((edge&4) && indices2(xi,0)<0) {
              const float Xi = X + (isovalue-val3)*dx/(val2-val3);
              indices2(xi,0) = nb_vertices++;
              add_vertex(Xi,nY,0.f);
            }
            if ((edge&8) && indices1(xi,1)<0) {
              const float Yi = Y + (isovalue-val0)*dy/(val3-val0);
              indices1(xi,1) = nb_vertices++;
              add_vertex(X,Yi,0.f);
            }

            // Create segments.
            for (const int *segment = segments[configuration]; *segment!=-1; ) {
              const unsigned int p0 = (unsigned int)*(segment++), p1 = (unsigned int)*(segment++);
              const int
                i0 = _isoline3d_index(p0,indices1,indices2,xi,nxi),
                i1 = _isoline3d_index(p1,indices1,indices2,xi,nxi);
              add_segment(i0,i1);
            }
          }
        }
        values1.swap(values2);
        indices1.swap(indices2);
      }
    }

    //! Compute isolines of a function, as a 3D object \overload.
    template<typename tf>
    static CImg<floatT> isoline3d(CImgList<tf>& primitives, const char *const expression, const float isovalue,
                                  const float x0, const float y0, const float x1, const float y1,
                                  const int size_x=256, const int size_y=256) {
      const _functor2d_expr func(expression);
      return isoline3d(primitives,func,isovalue,x0,y0,x1,y1,size_x,size_y);
    }

    template<typename t>
    static int _isoline3d_index(const unsigned int edge, const CImg<t>& indices1, const CImg<t>& indices2,
                                 const unsigned int x, const unsigned int nx) {
      switch (edge) {
      case 0 : return (int)indices1(x,0);
      case 1 : return (int)indices1(nx,1);
      case 2 : return (int)indices2(x,0);
      case 3 : return (int)indices1(x,1);
      }
      return 0;
    }

    //! Generate an isosurface from the instance image, as a 3D object.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param isovalue The scalar value used as the threshold for extraction.
       \param size_x Number of subdivisions along the X-axis.
       \param size_y Number of subdivisions along the Y-axis.
       \param size_z Number of subdivisions along the Z-axis.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       const CImg<float> img = CImg<unsigned char>("reference.jpg").resize(-100,-100,20);
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = img.get_isosurface3d(faces3d,100);
       CImg<unsigned char>().display_object3d("Isosurface3d",points3d,faces3d,colors3d);
       \endcode
       \image html ref_isosurface3d.jpg
    **/
    template<typename tf>
    CImg<floatT> get_isosurface3d(CImgList<tf>& primitives, const float isovalue,
                                  const int size_x=-100, const int size_y=-100, const int size_z=-100) const {
      if (_spectrum>1)
        throw CImgInstanceException(_cimg_instance
                                    "get_isosurface3d(): Instance is not a scalar image.",
                                    cimg_instance);
      primitives.assign();
      if (is_empty()) return *this;
      CImg<floatT> vertices;
      if ((size_x==-100 && size_y==-100 && size_z==-100) || (size_x==width() && size_y==height() && size_z==depth())) {
        const _functor3d_int func(*this);
        vertices = isosurface3d(primitives,func,isovalue,0,0,0,width() - 1.f,height() - 1.f,depth() - 1.f,
                                width(),height(),depth());
      } else {
        const _functor3d_float func(*this);
        vertices = isosurface3d(primitives,func,isovalue,0,0,0,width() - 1.f,height() - 1.f,depth() - 1.f,
                                size_x,size_y,size_z);
      }
      return vertices;
    }

    //! Compute isosurface of a function, as a 3D object.
    /**
       \param[out] primitives Primitives data of the resulting 3D object.
       \param func Implicit function. Is of type <tt>float (*func)(const float x, const float y, const float z)</tt>.
       \param isovalue The scalar value used as the threshold for extraction.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param z0 Z-coordinate of the starting point.
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param z1 Z-coordinate of the ending point.
       \param size_x Resolution of the elevation function along the X-axis.
       \param size_y Resolution of the elevation function along the Y-axis.
       \param size_z Resolution of the elevation function along the Z-axis.
       \note Uses the marching cubes algorithm for extracting the isosurface.
     **/
    template<typename tf, typename tfunc>
    static CImg<floatT> isosurface3d(CImgList<tf>& primitives, const tfunc& func, const float isovalue,
                                     const float x0, const float y0, const float z0,
                                     const float x1, const float y1, const float z1,
                                     const int size_x=32, const int size_y=32, const int size_z=32) {
      CImgList<floatT> vertices;
      primitives.assign();
      typename CImg<floatT>::_functor_isosurface3d add_vertex(vertices);
      typename CImg<tf>::_functor_isosurface3d add_triangle(primitives);
      isosurface3d(add_vertex,add_triangle,func,isovalue,x0,y0,z0,x1,y1,z1,size_x,size_y,size_z);
      return vertices>'x';
    }

    //! Compute isosurface of a function, as a 3D object.
    /**
       \param[out] add_vertex : Functor with operator()(x,y,z) defined for adding a new vertex.
       \param[out] add_triangle : Functor with operator()(i,j) defined for adding a new segment.
       \param func Implicit function. Is of type <tt>float (*func)(const float x, const float y, const float z)</tt>.
       \param isovalue The scalar value used as the threshold for extraction.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param z0 Z-coordinate of the starting point.
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param z1 Z-coordinate of the ending point.
       \param size_x Resolution of the elevation function along the X-axis.
       \param size_y Resolution of the elevation function along the Y-axis.
       \param size_z Resolution of the elevation function along the Z-axis.
       \note Uses the marching cubes algorithm for extracting the isosurface.
     **/
    template<typename tv, typename tf, typename tfunc>
    static void isosurface3d(tv& add_vertex, tf& add_triangle, const tfunc& func, const float isovalue,
                             const float x0, const float y0, const float z0,
                             const float x1, const float y1, const float z1,
                             const int size_x, const int size_y, const int size_z) {
      static const unsigned int edges[256] = {
        0x000, 0x109, 0x203, 0x30a, 0x406, 0x50f, 0x605, 0x70c, 0x80c, 0x905, 0xa0f, 0xb06, 0xc0a, 0xd03, 0xe09, 0xf00,
        0x190, 0x99 , 0x393, 0x29a, 0x596, 0x49f, 0x795, 0x69c, 0x99c, 0x895, 0xb9f, 0xa96, 0xd9a, 0xc93, 0xf99, 0xe90,
        0x230, 0x339, 0x33 , 0x13a, 0x636, 0x73f, 0x435, 0x53c, 0xa3c, 0xb35, 0x83f, 0x936, 0xe3a, 0xf33, 0xc39, 0xd30,
        0x3a0, 0x2a9, 0x1a3, 0xaa , 0x7a6, 0x6af, 0x5a5, 0x4ac, 0xbac, 0xaa5, 0x9af, 0x8a6, 0xfaa, 0xea3, 0xda9, 0xca0,
        0x460, 0x569, 0x663, 0x76a, 0x66 , 0x16f, 0x265, 0x36c, 0xc6c, 0xd65, 0xe6f, 0xf66, 0x86a, 0x963, 0xa69, 0xb60,
        0x5f0, 0x4f9, 0x7f3, 0x6fa, 0x1f6, 0xff , 0x3f5, 0x2fc, 0xdfc, 0xcf5, 0xfff, 0xef6, 0x9fa, 0x8f3, 0xbf9, 0xaf0,
        0x650, 0x759, 0x453, 0x55a, 0x256, 0x35f, 0x55 , 0x15c, 0xe5c, 0xf55, 0xc5f, 0xd56, 0xa5a, 0xb53, 0x859, 0x950,
        0x7c0, 0x6c9, 0x5c3, 0x4ca, 0x3c6, 0x2cf, 0x1c5, 0xcc , 0xfcc, 0xec5, 0xdcf, 0xcc6, 0xbca, 0xac3, 0x9c9, 0x8c0,
        0x8c0, 0x9c9, 0xac3, 0xbca, 0xcc6, 0xdcf, 0xec5, 0xfcc, 0xcc , 0x1c5, 0x2cf, 0x3c6, 0x4ca, 0x5c3, 0x6c9, 0x7c0,
        0x950, 0x859, 0xb53, 0xa5a, 0xd56, 0xc5f, 0xf55, 0xe5c, 0x15c, 0x55 , 0x35f, 0x256, 0x55a, 0x453, 0x759, 0x650,
        0xaf0, 0xbf9, 0x8f3, 0x9fa, 0xef6, 0xfff, 0xcf5, 0xdfc, 0x2fc, 0x3f5, 0xff , 0x1f6, 0x6fa, 0x7f3, 0x4f9, 0x5f0,
        0xb60, 0xa69, 0x963, 0x86a, 0xf66, 0xe6f, 0xd65, 0xc6c, 0x36c, 0x265, 0x16f, 0x66 , 0x76a, 0x663, 0x569, 0x460,
        0xca0, 0xda9, 0xea3, 0xfaa, 0x8a6, 0x9af, 0xaa5, 0xbac, 0x4ac, 0x5a5, 0x6af, 0x7a6, 0xaa , 0x1a3, 0x2a9, 0x3a0,
        0xd30, 0xc39, 0xf33, 0xe3a, 0x936, 0x83f, 0xb35, 0xa3c, 0x53c, 0x435, 0x73f, 0x636, 0x13a, 0x33 , 0x339, 0x230,
        0xe90, 0xf99, 0xc93, 0xd9a, 0xa96, 0xb9f, 0x895, 0x99c, 0x69c, 0x795, 0x49f, 0x596, 0x29a, 0x393, 0x99 , 0x190,
        0xf00, 0xe09, 0xd03, 0xc0a, 0xb06, 0xa0f, 0x905, 0x80c, 0x70c, 0x605, 0x50f, 0x406, 0x30a, 0x203, 0x109, 0x000
      };

      static const int triangles[256][16] = {
        { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 1, 9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 8, 3, 9, 8, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, 1, 2, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 2, 10, 0, 2, 9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 8, 3, 2, 10, 8, 10, 9, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 11, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 11, 2, 8, 11, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 9, 0, 2, 3, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 11, 2, 1, 9, 11, 9, 8, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 10, 1, 11, 10, 3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 10, 1, 0, 8, 10, 8, 11, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 9, 0, 3, 11, 9, 11, 10, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 8, 10, 10, 8, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 7, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 3, 0, 7, 3, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 1, 9, 8, 4, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 1, 9, 4, 7, 1, 7, 3, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, 8, 4, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 4, 7, 3, 0, 4, 1, 2, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 2, 10, 9, 0, 2, 8, 4, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 10, 9, 2, 9, 7, 2, 7, 3, 7, 9, 4, -1, -1, -1, -1 },
        { 8, 4, 7, 3, 11, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 4, 7, 11, 2, 4, 2, 0, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 0, 1, 8, 4, 7, 2, 3, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 7, 11, 9, 4, 11, 9, 11, 2, 9, 2, 1, -1, -1, -1, -1 },
        { 3, 10, 1, 3, 11, 10, 7, 8, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 11, 10, 1, 4, 11, 1, 0, 4, 7, 11, 4, -1, -1, -1, -1 },
        { 4, 7, 8, 9, 0, 11, 9, 11, 10, 11, 0, 3, -1, -1, -1, -1 },
        { 4, 7, 11, 4, 11, 9, 9, 11, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 5, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 5, 4, 0, 8, 3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 5, 4, 1, 5, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 5, 4, 8, 3, 5, 3, 1, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, 9, 5, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 0, 8, 1, 2, 10, 4, 9, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 2, 10, 5, 4, 2, 4, 0, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 10, 5, 3, 2, 5, 3, 5, 4, 3, 4, 8, -1, -1, -1, -1 },
        { 9, 5, 4, 2, 3, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 11, 2, 0, 8, 11, 4, 9, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 5, 4, 0, 1, 5, 2, 3, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 1, 5, 2, 5, 8, 2, 8, 11, 4, 8, 5, -1, -1, -1, -1 },
        { 10, 3, 11, 10, 1, 3, 9, 5, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 9, 5, 0, 8, 1, 8, 10, 1, 8, 11, 10, -1, -1, -1, -1 },
        { 5, 4, 0, 5, 0, 11, 5, 11, 10, 11, 0, 3, -1, -1, -1, -1 },
        { 5, 4, 8, 5, 8, 10, 10, 8, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 7, 8, 5, 7, 9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 3, 0, 9, 5, 3, 5, 7, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 7, 8, 0, 1, 7, 1, 5, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 5, 3, 3, 5, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 7, 8, 9, 5, 7, 10, 1, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 1, 2, 9, 5, 0, 5, 3, 0, 5, 7, 3, -1, -1, -1, -1 },
        { 8, 0, 2, 8, 2, 5, 8, 5, 7, 10, 5, 2, -1, -1, -1, -1 },
        { 2, 10, 5, 2, 5, 3, 3, 5, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 9, 5, 7, 8, 9, 3, 11, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 5, 7, 9, 7, 2, 9, 2, 0, 2, 7, 11, -1, -1, -1, -1 },
        { 2, 3, 11, 0, 1, 8, 1, 7, 8, 1, 5, 7, -1, -1, -1, -1 },
        { 11, 2, 1, 11, 1, 7, 7, 1, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 5, 8, 8, 5, 7, 10, 1, 3, 10, 3, 11, -1, -1, -1, -1 },
        { 5, 7, 0, 5, 0, 9, 7, 11, 0, 1, 0, 10, 11, 10, 0, -1 },
        { 11, 10, 0, 11, 0, 3, 10, 5, 0, 8, 0, 7, 5, 7, 0, -1 },
        { 11, 10, 5, 7, 11, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 6, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, 5, 10, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 0, 1, 5, 10, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 8, 3, 1, 9, 8, 5, 10, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 6, 5, 2, 6, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 6, 5, 1, 2, 6, 3, 0, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 6, 5, 9, 0, 6, 0, 2, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 9, 8, 5, 8, 2, 5, 2, 6, 3, 2, 8, -1, -1, -1, -1 },
        { 2, 3, 11, 10, 6, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 0, 8, 11, 2, 0, 10, 6, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 1, 9, 2, 3, 11, 5, 10, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 10, 6, 1, 9, 2, 9, 11, 2, 9, 8, 11, -1, -1, -1, -1 },
        { 6, 3, 11, 6, 5, 3, 5, 1, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 11, 0, 11, 5, 0, 5, 1, 5, 11, 6, -1, -1, -1, -1 },
        { 3, 11, 6, 0, 3, 6, 0, 6, 5, 0, 5, 9, -1, -1, -1, -1 },
        { 6, 5, 9, 6, 9, 11, 11, 9, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 10, 6, 4, 7, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 3, 0, 4, 7, 3, 6, 5, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 9, 0, 5, 10, 6, 8, 4, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 6, 5, 1, 9, 7, 1, 7, 3, 7, 9, 4, -1, -1, -1, -1 },
        { 6, 1, 2, 6, 5, 1, 4, 7, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 5, 5, 2, 6, 3, 0, 4, 3, 4, 7, -1, -1, -1, -1 },
        { 8, 4, 7, 9, 0, 5, 0, 6, 5, 0, 2, 6, -1, -1, -1, -1 },
        { 7, 3, 9, 7, 9, 4, 3, 2, 9, 5, 9, 6, 2, 6, 9, -1 },
        { 3, 11, 2, 7, 8, 4, 10, 6, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 10, 6, 4, 7, 2, 4, 2, 0, 2, 7, 11, -1, -1, -1, -1 },
        { 0, 1, 9, 4, 7, 8, 2, 3, 11, 5, 10, 6, -1, -1, -1, -1 },
        { 9, 2, 1, 9, 11, 2, 9, 4, 11, 7, 11, 4, 5, 10, 6, -1 },
        { 8, 4, 7, 3, 11, 5, 3, 5, 1, 5, 11, 6, -1, -1, -1, -1 },
        { 5, 1, 11, 5, 11, 6, 1, 0, 11, 7, 11, 4, 0, 4, 11, -1 },
        { 0, 5, 9, 0, 6, 5, 0, 3, 6, 11, 6, 3, 8, 4, 7, -1 },
        { 6, 5, 9, 6, 9, 11, 4, 7, 9, 7, 11, 9, -1, -1, -1, -1 },
        { 10, 4, 9, 6, 4, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 10, 6, 4, 9, 10, 0, 8, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 0, 1, 10, 6, 0, 6, 4, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 3, 1, 8, 1, 6, 8, 6, 4, 6, 1, 10, -1, -1, -1, -1 },
        { 1, 4, 9, 1, 2, 4, 2, 6, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 0, 8, 1, 2, 9, 2, 4, 9, 2, 6, 4, -1, -1, -1, -1 },
        { 0, 2, 4, 4, 2, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 3, 2, 8, 2, 4, 4, 2, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 4, 9, 10, 6, 4, 11, 2, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 2, 2, 8, 11, 4, 9, 10, 4, 10, 6, -1, -1, -1, -1 },
        { 3, 11, 2, 0, 1, 6, 0, 6, 4, 6, 1, 10, -1, -1, -1, -1 },
        { 6, 4, 1, 6, 1, 10, 4, 8, 1, 2, 1, 11, 8, 11, 1, -1 },
        { 9, 6, 4, 9, 3, 6, 9, 1, 3, 11, 6, 3, -1, -1, -1, -1 },
        { 8, 11, 1, 8, 1, 0, 11, 6, 1, 9, 1, 4, 6, 4, 1, -1 },
        { 3, 11, 6, 3, 6, 0, 0, 6, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 6, 4, 8, 11, 6, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 10, 6, 7, 8, 10, 8, 9, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 7, 3, 0, 10, 7, 0, 9, 10, 6, 7, 10, -1, -1, -1, -1 },
        { 10, 6, 7, 1, 10, 7, 1, 7, 8, 1, 8, 0, -1, -1, -1, -1 },
        { 10, 6, 7, 10, 7, 1, 1, 7, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 6, 1, 6, 8, 1, 8, 9, 8, 6, 7, -1, -1, -1, -1 },
        { 2, 6, 9, 2, 9, 1, 6, 7, 9, 0, 9, 3, 7, 3, 9, -1 },
        { 7, 8, 0, 7, 0, 6, 6, 0, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 3, 2, 6, 7, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 3, 11, 10, 6, 8, 10, 8, 9, 8, 6, 7, -1, -1, -1, -1 },
        { 2, 0, 7, 2, 7, 11, 0, 9, 7, 6, 7, 10, 9, 10, 7, -1 },
        { 1, 8, 0, 1, 7, 8, 1, 10, 7, 6, 7, 10, 2, 3, 11, -1 },
        { 11, 2, 1, 11, 1, 7, 10, 6, 1, 6, 7, 1, -1, -1, -1, -1 },
        { 8, 9, 6, 8, 6, 7, 9, 1, 6, 11, 6, 3, 1, 3, 6, -1 },
        { 0, 9, 1, 11, 6, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 8, 0, 7, 0, 6, 3, 11, 0, 11, 6, 0, -1, -1, -1, -1 },
        { 7, 11, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 6, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 0, 8, 11, 7, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 1, 9, 11, 7, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 1, 9, 8, 3, 1, 11, 7, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 1, 2, 6, 11, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, 3, 0, 8, 6, 11, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 9, 0, 2, 10, 9, 6, 11, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 6, 11, 7, 2, 10, 3, 10, 8, 3, 10, 9, 8, -1, -1, -1, -1 },
        { 7, 2, 3, 6, 2, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 7, 0, 8, 7, 6, 0, 6, 2, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 7, 6, 2, 3, 7, 0, 1, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 6, 2, 1, 8, 6, 1, 9, 8, 8, 7, 6, -1, -1, -1, -1 },
        { 10, 7, 6, 10, 1, 7, 1, 3, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 7, 6, 1, 7, 10, 1, 8, 7, 1, 0, 8, -1, -1, -1, -1 },
        { 0, 3, 7, 0, 7, 10, 0, 10, 9, 6, 10, 7, -1, -1, -1, -1 },
        { 7, 6, 10, 7, 10, 8, 8, 10, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 6, 8, 4, 11, 8, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 6, 11, 3, 0, 6, 0, 4, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 6, 11, 8, 4, 6, 9, 0, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 4, 6, 9, 6, 3, 9, 3, 1, 11, 3, 6, -1, -1, -1, -1 },
        { 6, 8, 4, 6, 11, 8, 2, 10, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, 3, 0, 11, 0, 6, 11, 0, 4, 6, -1, -1, -1, -1 },
        { 4, 11, 8, 4, 6, 11, 0, 2, 9, 2, 10, 9, -1, -1, -1, -1 },
        { 10, 9, 3, 10, 3, 2, 9, 4, 3, 11, 3, 6, 4, 6, 3, -1 },
        { 8, 2, 3, 8, 4, 2, 4, 6, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 4, 2, 4, 6, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 9, 0, 2, 3, 4, 2, 4, 6, 4, 3, 8, -1, -1, -1, -1 },
        { 1, 9, 4, 1, 4, 2, 2, 4, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 1, 3, 8, 6, 1, 8, 4, 6, 6, 10, 1, -1, -1, -1, -1 },
        { 10, 1, 0, 10, 0, 6, 6, 0, 4, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 6, 3, 4, 3, 8, 6, 10, 3, 0, 3, 9, 10, 9, 3, -1 },
        { 10, 9, 4, 6, 10, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 9, 5, 7, 6, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, 4, 9, 5, 11, 7, 6, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 0, 1, 5, 4, 0, 7, 6, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 7, 6, 8, 3, 4, 3, 5, 4, 3, 1, 5, -1, -1, -1, -1 },
        { 9, 5, 4, 10, 1, 2, 7, 6, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 6, 11, 7, 1, 2, 10, 0, 8, 3, 4, 9, 5, -1, -1, -1, -1 },
        { 7, 6, 11, 5, 4, 10, 4, 2, 10, 4, 0, 2, -1, -1, -1, -1 },
        { 3, 4, 8, 3, 5, 4, 3, 2, 5, 10, 5, 2, 11, 7, 6, -1 },
        { 7, 2, 3, 7, 6, 2, 5, 4, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 5, 4, 0, 8, 6, 0, 6, 2, 6, 8, 7, -1, -1, -1, -1 },
        { 3, 6, 2, 3, 7, 6, 1, 5, 0, 5, 4, 0, -1, -1, -1, -1 },
        { 6, 2, 8, 6, 8, 7, 2, 1, 8, 4, 8, 5, 1, 5, 8, -1 },
        { 9, 5, 4, 10, 1, 6, 1, 7, 6, 1, 3, 7, -1, -1, -1, -1 },
        { 1, 6, 10, 1, 7, 6, 1, 0, 7, 8, 7, 0, 9, 5, 4, -1 },
        { 4, 0, 10, 4, 10, 5, 0, 3, 10, 6, 10, 7, 3, 7, 10, -1 },
        { 7, 6, 10, 7, 10, 8, 5, 4, 10, 4, 8, 10, -1, -1, -1, -1 },
        { 6, 9, 5, 6, 11, 9, 11, 8, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 6, 11, 0, 6, 3, 0, 5, 6, 0, 9, 5, -1, -1, -1, -1 },
        { 0, 11, 8, 0, 5, 11, 0, 1, 5, 5, 6, 11, -1, -1, -1, -1 },
        { 6, 11, 3, 6, 3, 5, 5, 3, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 10, 9, 5, 11, 9, 11, 8, 11, 5, 6, -1, -1, -1, -1 },
        { 0, 11, 3, 0, 6, 11, 0, 9, 6, 5, 6, 9, 1, 2, 10, -1 },
        { 11, 8, 5, 11, 5, 6, 8, 0, 5, 10, 5, 2, 0, 2, 5, -1 },
        { 6, 11, 3, 6, 3, 5, 2, 10, 3, 10, 5, 3, -1, -1, -1, -1 },
        { 5, 8, 9, 5, 2, 8, 5, 6, 2, 3, 8, 2, -1, -1, -1, -1 },
        { 9, 5, 6, 9, 6, 0, 0, 6, 2, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 5, 8, 1, 8, 0, 5, 6, 8, 3, 8, 2, 6, 2, 8, -1 },
        { 1, 5, 6, 2, 1, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 3, 6, 1, 6, 10, 3, 8, 6, 5, 6, 9, 8, 9, 6, -1 },
        { 10, 1, 0, 10, 0, 6, 9, 5, 0, 5, 6, 0, -1, -1, -1, -1 },
        { 0, 3, 8, 5, 6, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 5, 6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 5, 10, 7, 5, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 5, 10, 11, 7, 5, 8, 3, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 11, 7, 5, 10, 11, 1, 9, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 10, 7, 5, 10, 11, 7, 9, 8, 1, 8, 3, 1, -1, -1, -1, -1 },
        { 11, 1, 2, 11, 7, 1, 7, 5, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, 1, 2, 7, 1, 7, 5, 7, 2, 11, -1, -1, -1, -1 },
        { 9, 7, 5, 9, 2, 7, 9, 0, 2, 2, 11, 7, -1, -1, -1, -1 },
        { 7, 5, 2, 7, 2, 11, 5, 9, 2, 3, 2, 8, 9, 8, 2, -1 },
        { 2, 5, 10, 2, 3, 5, 3, 7, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 2, 0, 8, 5, 2, 8, 7, 5, 10, 2, 5, -1, -1, -1, -1 },
        { 9, 0, 1, 5, 10, 3, 5, 3, 7, 3, 10, 2, -1, -1, -1, -1 },
        { 9, 8, 2, 9, 2, 1, 8, 7, 2, 10, 2, 5, 7, 5, 2, -1 },
        { 1, 3, 5, 3, 7, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 7, 0, 7, 1, 1, 7, 5, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 0, 3, 9, 3, 5, 5, 3, 7, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 8, 7, 5, 9, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 8, 4, 5, 10, 8, 10, 11, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 5, 0, 4, 5, 11, 0, 5, 10, 11, 11, 3, 0, -1, -1, -1, -1 },
        { 0, 1, 9, 8, 4, 10, 8, 10, 11, 10, 4, 5, -1, -1, -1, -1 },
        { 10, 11, 4, 10, 4, 5, 11, 3, 4, 9, 4, 1, 3, 1, 4, -1 },
        { 2, 5, 1, 2, 8, 5, 2, 11, 8, 4, 5, 8, -1, -1, -1, -1 },
        { 0, 4, 11, 0, 11, 3, 4, 5, 11, 2, 11, 1, 5, 1, 11, -1 },
        { 0, 2, 5, 0, 5, 9, 2, 11, 5, 4, 5, 8, 11, 8, 5, -1 },
        { 9, 4, 5, 2, 11, 3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 5, 10, 3, 5, 2, 3, 4, 5, 3, 8, 4, -1, -1, -1, -1 },
        { 5, 10, 2, 5, 2, 4, 4, 2, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 10, 2, 3, 5, 10, 3, 8, 5, 4, 5, 8, 0, 1, 9, -1 },
        { 5, 10, 2, 5, 2, 4, 1, 9, 2, 9, 4, 2, -1, -1, -1, -1 },
        { 8, 4, 5, 8, 5, 3, 3, 5, 1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 4, 5, 1, 0, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 8, 4, 5, 8, 5, 3, 9, 0, 5, 0, 3, 5, -1, -1, -1, -1 },
        { 9, 4, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 11, 7, 4, 9, 11, 9, 10, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 8, 3, 4, 9, 7, 9, 11, 7, 9, 10, 11, -1, -1, -1, -1 },
        { 1, 10, 11, 1, 11, 4, 1, 4, 0, 7, 4, 11, -1, -1, -1, -1 },
        { 3, 1, 4, 3, 4, 8, 1, 10, 4, 7, 4, 11, 10, 11, 4, -1 },
        { 4, 11, 7, 9, 11, 4, 9, 2, 11, 9, 1, 2, -1, -1, -1, -1 },
        { 9, 7, 4, 9, 11, 7, 9, 1, 11, 2, 11, 1, 0, 8, 3, -1 },
        { 11, 7, 4, 11, 4, 2, 2, 4, 0, -1, -1, -1, -1, -1, -1, -1 },
        { 11, 7, 4, 11, 4, 2, 8, 3, 4, 3, 2, 4, -1, -1, -1, -1 },
        { 2, 9, 10, 2, 7, 9, 2, 3, 7, 7, 4, 9, -1, -1, -1, -1 },
        { 9, 10, 7, 9, 7, 4, 10, 2, 7, 8, 7, 0, 2, 0, 7, -1 },
        { 3, 7, 10, 3, 10, 2, 7, 4, 10, 1, 10, 0, 4, 0, 10, -1 },
        { 1, 10, 2, 8, 7, 4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 9, 1, 4, 1, 7, 7, 1, 3, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 9, 1, 4, 1, 7, 0, 8, 1, 8, 7, 1, -1, -1, -1, -1 },
        { 4, 0, 3, 7, 4, 3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 4, 8, 7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 10, 8, 10, 11, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 0, 9, 3, 9, 11, 11, 9, 10, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 1, 10, 0, 10, 8, 8, 10, 11, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 1, 10, 11, 3, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 2, 11, 1, 11, 9, 9, 11, 8, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 0, 9, 3, 9, 11, 1, 2, 9, 2, 11, 9, -1, -1, -1, -1 },
        { 0, 2, 11, 8, 0, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 3, 2, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 3, 8, 2, 8, 10, 10, 8, 9, -1, -1, -1, -1, -1, -1, -1 },
        { 9, 10, 2, 0, 9, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 2, 3, 8, 2, 8, 10, 0, 1, 8, 1, 10, 8, -1, -1, -1, -1 },
        { 1, 10, 2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 1, 3, 8, 9, 1, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 9, 1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { 0, 3, 8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
        { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }
      };

      const unsigned int
        _nx = (unsigned int)(size_x>=0?size_x:cimg::round((x1-x0)*-size_x/100 + 1)),
        _ny = (unsigned int)(size_y>=0?size_y:cimg::round((y1-y0)*-size_y/100 + 1)),
        _nz = (unsigned int)(size_z>=0?size_z:cimg::round((z1-z0)*-size_z/100 + 1)),
        nx = _nx?_nx:1,
        ny = _ny?_ny:1,
        nz = _nz?_nz:1,
        nxm1 = nx - 1,
        nym1 = ny - 1,
        nzm1 = nz - 1;
      if (!nxm1 || !nym1 || !nzm1) return;
      const float dx = (x1 - x0)/nxm1, dy = (y1 - y0)/nym1, dz = (z1 - z0)/nzm1;
      CImg<intT> indices1(nx,ny,1,3,-1), indices2(indices1);
      CImg<floatT> values1(nx,ny), values2(nx,ny);
      float X = 0, Y = 0, Z = 0, nX = 0, nY = 0, nZ = 0;
      int nb_vertices = 0;

      // Fill the first plane with function values.
      Y = y0;
      cimg_forY(values1,y) {
        X = x0;
        cimg_forX(values1,x) { values1(x,y) = (float)func(X,Y,z0); X+=dx; }
        Y+=dy;
      }

      // Run Marching Cubes algorithm.
      Z = z0; nZ = Z + dz;
      for (unsigned int zi = 0; zi<nzm1; ++zi, Z = nZ, nZ+=dz) {
        Y = y0; nY = Y + dy;
        indices2.fill(-1);
        X = x0; for (unsigned int xi = 0; xi<nx; ++xi) { values2(xi,0) = (float)func(X,Y,nZ); X += dx; }

        for (unsigned int yi = 0, nyi = 1; yi<nym1; ++yi, ++nyi, Y = nY, nY+=dy) {
          X = x0; nX = X + dx;
          values2(0,nyi) = (float)func(X,nY,nZ);

          for (unsigned int xi = 0, nxi = 1; xi<nxm1; ++xi, ++nxi, X = nX, nX+=dx) {

            // Determine cube configuration.
            const float
              val0 = values1(xi,yi),
              val1 = values1(nxi,yi),
              val2 = values1(nxi,nyi),
              val3 = values1(xi,nyi),
              val4 = values2(xi,yi),
              val5 = values2(nxi,yi),
              val6 = values2(nxi,nyi) = (float)func(nX,nY,nZ),
              val7 = values2(xi,nyi);

            const unsigned int configuration =
              (val0<isovalue?1U:0U)  | (val1<isovalue?2U:0U)  | (val2<isovalue?4U:0U)  | (val3<isovalue?8U:0U) |
              (val4<isovalue?16U:0U) | (val5<isovalue?32U:0U) | (val6<isovalue?64U:0U) | (val7<isovalue?128U:0U),
              edge = edges[configuration];

            // Compute intersection vertices.
            if (edge) {
              if ((edge&1) && indices1(xi,yi,0)<0) {
                const float Xi = X + (isovalue-val0)*dx/(val1-val0);
                indices1(xi,yi,0) = nb_vertices++;
                add_vertex(Xi,Y,Z);
              }
              if ((edge&2) && indices1(nxi,yi,1)<0) {
                const float Yi = Y + (isovalue-val1)*dy/(val2-val1);
                indices1(nxi,yi,1) = nb_vertices++;
                add_vertex(nX,Yi,Z);
              }
              if ((edge&4) && indices1(xi,nyi,0)<0) {
                const float Xi = X + (isovalue-val3)*dx/(val2-val3);
                indices1(xi,nyi,0) = nb_vertices++;
                add_vertex(Xi,nY,Z);
              }
              if ((edge&8) && indices1(xi,yi,1)<0) {
                const float Yi = Y + (isovalue-val0)*dy/(val3-val0);
                indices1(xi,yi,1) = nb_vertices++;
                add_vertex(X,Yi,Z);
              }
              if ((edge&16) && indices2(xi,yi,0)<0) {
                const float Xi = X + (isovalue-val4)*dx/(val5-val4);
                indices2(xi,yi,0) = nb_vertices++;
                add_vertex(Xi,Y,nZ);
              }
              if ((edge&32) && indices2(nxi,yi,1)<0) {
                const float Yi = Y + (isovalue-val5)*dy/(val6-val5);
                indices2(nxi,yi,1) = nb_vertices++;
                add_vertex(nX,Yi,nZ);
              }
              if ((edge&64) && indices2(xi,nyi,0)<0) {
                const float Xi = X + (isovalue-val7)*dx/(val6-val7);
                indices2(xi,nyi,0) = nb_vertices++;
                add_vertex(Xi,nY,nZ);
              }
              if ((edge&128) && indices2(xi,yi,1)<0)  {
                const float Yi = Y + (isovalue-val4)*dy/(val7-val4);
                indices2(xi,yi,1) = nb_vertices++;
                add_vertex(X,Yi,nZ);
              }
              if ((edge&256) && indices1(xi,yi,2)<0) {
                const float Zi = Z+ (isovalue-val0)*dz/(val4-val0);
                indices1(xi,yi,2) = nb_vertices++;
                add_vertex(X,Y,Zi);
              }
              if ((edge&512) && indices1(nxi,yi,2)<0)  {
                const float Zi = Z + (isovalue-val1)*dz/(val5-val1);
                indices1(nxi,yi,2) = nb_vertices++;
                add_vertex(nX,Y,Zi);
              }
              if ((edge&1024) && indices1(nxi,nyi,2)<0) {
                const float Zi = Z + (isovalue-val2)*dz/(val6-val2);
                indices1(nxi,nyi,2) = nb_vertices++;
                add_vertex(nX,nY,Zi);
              }
              if ((edge&2048) && indices1(xi,nyi,2)<0) {
                const float Zi = Z + (isovalue-val3)*dz/(val7-val3);
                indices1(xi,nyi,2) = nb_vertices++;
                add_vertex(X,nY,Zi);
              }

              // Create triangles.
              for (const int *triangle = triangles[configuration]; *triangle!=-1; ) {
                const unsigned int
                  p0 = (unsigned int)*(triangle++),
                  p1 = (unsigned int)*(triangle++),
                  p2 = (unsigned int)*(triangle++);
                const int
                  i0 = _isosurface3d_index(p0,indices1,indices2,xi,yi,nxi,nyi),
                  i1 = _isosurface3d_index(p1,indices1,indices2,xi,yi,nxi,nyi),
                  i2 = _isosurface3d_index(p2,indices1,indices2,xi,yi,nxi,nyi);
                add_triangle(i0,i2,i1);
              }
            }
          }
        }
        cimg::swap(values1,values2);
        cimg::swap(indices1,indices2);
      }
    }

    //! Compute isosurface of a function, as a 3D object \overload.
    template<typename tf>
    static CImg<floatT> isosurface3d(CImgList<tf>& primitives, const char *const expression, const float isovalue,
                                     const float x0, const float y0, const float z0,
                                     const float x1, const float y1, const float z1,
                                     const int dx=32, const int dy=32, const int dz=32) {
      const _functor3d_expr func(expression);
      return isosurface3d(primitives,func,isovalue,x0,y0,z0,x1,y1,z1,dx,dy,dz);
    }

    template<typename t>
    static int _isosurface3d_index(const unsigned int edge, const CImg<t>& indices1, const CImg<t>& indices2,
                                    const unsigned int x, const unsigned int y,
                                    const unsigned int nx, const unsigned int ny) {
      switch (edge) {
      case 0 : return indices1(x,y,0);
      case 1 : return indices1(nx,y,1);
      case 2 : return indices1(x,ny,0);
      case 3 : return indices1(x,y,1);
      case 4 : return indices2(x,y,0);
      case 5 : return indices2(nx,y,1);
      case 6 : return indices2(x,ny,0);
      case 7 : return indices2(x,y,1);
      case 8 : return indices1(x,y,2);
      case 9 : return indices1(nx,y,2);
      case 10 : return indices1(nx,ny,2);
      case 11 : return indices1(x,ny,2);
      }
      return 0;
    }

    // Define functors for accessing image values (used in previous functions).
    struct _functor2d_int {
      const CImg<T>& ref;
      _functor2d_int(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y) const {
        return (float)ref((int)x,(int)y);
      }
    };

    struct _functor2d_float {
      const CImg<T>& ref;
      _functor2d_float(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y) const {
        return (float)ref._linear_atXY(x,y);
      }
    };

    struct _functor2d_expr {
      _cimg_math_parser *mp;
      ~_functor2d_expr() { mp->end(); delete mp; }
      _functor2d_expr(const char *const expr):mp(0) {
        mp = new _cimg_math_parser(expr,0,CImg<T>::const_empty(),0);
      }
      float operator()(const float x, const float y) const {
        return (float)(*mp)(x,y,0,0);
      }
    };

    struct _functor3d_int {
      const CImg<T>& ref;
      _functor3d_int(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y, const float z) const {
        return (float)ref((int)x,(int)y,(int)z);
      }
    };

    struct _functor3d_float {
      const CImg<T>& ref;
      _functor3d_float(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y, const float z) const {
        return (float)ref._linear_atXYZ(x,y,z);
      }
    };

    struct _functor3d_expr {
      _cimg_math_parser *mp;
      ~_functor3d_expr() { mp->end(); delete mp; }
      _functor3d_expr(const char *const expr):mp(0) {
        mp = new _cimg_math_parser(expr,0,CImg<T>::const_empty(),0);
      }
      float operator()(const float x, const float y, const float z) const {
        return (float)(*mp)(x,y,z,0);
      }
    };

    struct _functor4d_int {
      const CImg<T>& ref;
      _functor4d_int(const CImg<T>& pref):ref(pref) {}
      float operator()(const float x, const float y, const float z, const unsigned int c) const {
        return (float)ref((int)x,(int)y,(int)z,c);
      }
    };

    struct _functor_isoline3d {
      CImgList<T>& list;
      _functor_isoline3d(CImgList<T>& _list):list(_list) {}
      template<typename t>
      void operator()(const t x, const t y, const t z) { CImg<T>::vector((T)x,(T)y,(T)z).move_to(list); }
      template<typename t>
      void operator()(const t i, const t j) { CImg<T>::vector((T)i,(T)j).move_to(list); }
    };

    struct _functor_isosurface3d {
      CImgList<T>& list;
      _functor_isosurface3d(CImgList<T>& _list):list(_list) {}
      template<typename t>
      void operator()(const t x, const t y, const t z) { CImg<T>::vector((T)x,(T)y,(T)z).move_to(list); }
    };

    //! Compute 3D elevation of a function as a 3D object.
    /**
       \param[out] primitives Primitives data of the resulting 3D object.
       \param func Elevation function. Is of type <tt>float (*func)(const float x,const float y)</tt>.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param size_x Resolution of the function along the X-axis.
       \param size_y Resolution of the function along the Y-axis.
    **/
    template<typename tf, typename tfunc>
    static CImg<floatT> elevation3d(CImgList<tf>& primitives, const tfunc& func,
                                    const float x0, const float y0, const float x1, const float y1,
                                    const int size_x=256, const int size_y=256) {
      const float
        nx0 = x0<x1?x0:x1, ny0 = y0<y1?y0:y1,
        nx1 = x0<x1?x1:x0, ny1 = y0<y1?y1:y0;
      const unsigned int
        _nsize_x = (unsigned int)(size_x>=0?size_x:(nx1-nx0)*-size_x/100),
        nsize_x = _nsize_x?_nsize_x:1, nsize_x1 = nsize_x - 1,
        _nsize_y = (unsigned int)(size_y>=0?size_y:(ny1-ny0)*-size_y/100),
        nsize_y = _nsize_y?_nsize_y:1, nsize_y1 = nsize_y - 1;
      if (nsize_x<2 || nsize_y<2)
        throw CImgArgumentException("CImg<%s>::elevation3d(): Invalid specified size (%d,%d).",
                                    pixel_type(),
                                    nsize_x,nsize_y);

      CImg<floatT> vertices(nsize_x*nsize_y,3);
      floatT *ptr_x = vertices.data(0,0), *ptr_y = vertices.data(0,1), *ptr_z = vertices.data(0,2);
      for (unsigned int y = 0; y<nsize_y; ++y) {
        const float Y = ny0 + y*(ny1-ny0)/nsize_y1;
        for (unsigned int x = 0; x<nsize_x; ++x) {
          const float X = nx0 + x*(nx1-nx0)/nsize_x1;
          *(ptr_x++) = (float)x;
          *(ptr_y++) = (float)y;
          *(ptr_z++) = (float)func(X,Y);
        }
      }
      primitives.assign(nsize_x1*nsize_y1,1,4);
      for (unsigned int p = 0, y = 0; y<nsize_y1; ++y) {
        const unsigned int yw = y*nsize_x;
        for (unsigned int x = 0; x<nsize_x1; ++x) {
          const unsigned int xpyw = x + yw, xpyww = xpyw + nsize_x;
          primitives[p++].fill(xpyw,xpyww,xpyww + 1,xpyw + 1);
        }
      }
      return vertices;
    }

    //! Compute 3D elevation of a function, as a 3D object \overload.
    template<typename tf>
    static CImg<floatT> elevation3d(CImgList<tf>& primitives, const char *const expression,
                                    const float x0, const float y0, const float x1, const float y1,
                                    const int size_x=256, const int size_y=256) {
      const _functor2d_expr func(expression);
      return elevation3d(primitives,func,x0,y0,x1,y1,size_x,size_y);
    }

    //! Generate a 3D box object.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param size_x The width of the box (dimension along the X-axis).
       \param size_y The height of the box (dimension along the Y-axis).
       \param size_z The depth of the box (dimension along the Z-axis).
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::box3d(faces3d,10,20,30);
       CImg<unsigned char>().display_object3d("Box3d",points3d,faces3d);
       \endcode
       \image html ref_box3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> box3d(CImgList<tf>& primitives,
                              const float size_x=200, const float size_y=100, const float size_z=100) {
      CImg<tf>(1,6*4,1,1, 0,3,2,1, 4,5,6,7, 0,1,5,4, 3,7,6,2, 0,4,7,3, 1,2,6,5).get_split('y',6).move_to(primitives);
      return CImg<floatT>(8,3,1,1,
                          0.,size_x,size_x,    0.,    0.,size_x,size_x,    0.,
                          0.,    0.,size_y,size_y,    0.,    0.,size_y,size_y,
                          0.,    0.,    0.,    0.,size_z,size_z,size_z,size_z);
    }

    //! Generate a 3D cone.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param radius The radius of the cone base.
       \param size_z The cone's height.
       \param subdivisions The number angular subdivisions for the base.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::cone3d(faces3d,50);
       CImg<unsigned char>().display_object3d("Cone3d",points3d,faces3d);
       \endcode
       \image html ref_cone3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> cone3d(CImgList<tf>& primitives,
                               const float radius=50, const float size_z=100, const unsigned int subdivisions=24) {
      primitives.assign();
      if (!subdivisions) return CImg<floatT>();
      CImgList<floatT> vertices(2);
      CImg<floatT>::vector(0.f,0.f,size_z).move_to(vertices[0]);
      CImg<floatT>::vector(0.f,0.f,0.f).move_to(vertices[1]);
      for (float delta = 360.f/subdivisions, angle = 0; angle<360; angle+=delta) {
        const float a = (float)(angle*cimg::PI/180);
        CImg<floatT>::vector((float)(radius*std::cos(a)),(float)(radius*std::sin(a)),0).move_to(vertices);
      }
      const unsigned int nbr = vertices._width - 2;
      for (unsigned int p = 0; p<nbr; ++p) {
        const unsigned int curr = 2 + p, next = 2 + ((p + 1)%nbr);
        CImg<tf>::vector(1,next,curr).move_to(primitives);
        CImg<tf>::vector(0,curr,next).move_to(primitives);
      }
      return vertices>'x';
    }

    //! Generate a 3D cylinder.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param radius The radius of the cylinder base.
       \param size_z The cylinder's height.
       \param subdivisions The number of angular subdivisions for the base.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::cylinder3d(faces3d,50);
       CImg<unsigned char>().display_object3d("Cylinder3d",points3d,faces3d);
       \endcode
       \image html ref_cylinder3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> cylinder3d(CImgList<tf>& primitives,
                                   const float radius=50, const float size_z=100, const unsigned int subdivisions=24) {
      primitives.assign();
      if (!subdivisions) return CImg<floatT>();
      CImgList<floatT> vertices(2,1,3,1,1,
                                0.,0.,0.,
                                0.,0.,size_z);
      for (float delta = 360.f/subdivisions, angle = 0; angle<360; angle+=delta) {
        const float a = (float)(angle*cimg::PI/180);
        CImg<floatT>::vector((float)(radius*std::cos(a)),(float)(radius*std::sin(a)),0.f).move_to(vertices);
        CImg<floatT>::vector((float)(radius*std::cos(a)),(float)(radius*std::sin(a)),size_z).move_to(vertices);
      }
      const unsigned int nbr = (vertices._width - 2)/2;
      for (unsigned int p = 0; p<nbr; ++p) {
        const unsigned int curr = 2 + 2*p, next = 2 + (2*((p + 1)%nbr));
        CImg<tf>::vector(0,next,curr).move_to(primitives);
        CImg<tf>::vector(1,curr + 1,next + 1).move_to(primitives);
        CImg<tf>::vector(curr,next,next + 1,curr + 1).move_to(primitives);
      }
      return vertices>'x';
    }

    //! Generate a 3D torus.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param radius1 The large radius.
       \param radius2 The small radius.
       \param subdivisions1 The number of angular subdivisions for the large radius.
       \param subdivisions2 The number of angular subdivisions for the small radius.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::torus3d(faces3d,20,4);
       CImg<unsigned char>().display_object3d("Torus3d",points3d,faces3d);
       \endcode
       \image html ref_torus3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> torus3d(CImgList<tf>& primitives,
                                const float radius1=100, const float radius2=30,
                                const unsigned int subdivisions1=24, const unsigned int subdivisions2=12) {
      primitives.assign();
      if (!subdivisions1 || !subdivisions2) return CImg<floatT>();
      CImgList<floatT> vertices;
      for (unsigned int v = 0; v<subdivisions1; ++v) {
        const float
          beta = (float)(v*2*cimg::PI/subdivisions1),
          xc = radius1*(float)std::cos(beta),
          yc = radius1*(float)std::sin(beta);
        for (unsigned int u = 0; u<subdivisions2; ++u) {
          const float
            alpha = (float)(u*2*cimg::PI/subdivisions2),
            x = xc + radius2*(float)(std::cos(alpha)*std::cos(beta)),
            y = yc + radius2*(float)(std::cos(alpha)*std::sin(beta)),
            z = radius2*(float)std::sin(alpha);
          CImg<floatT>::vector(x,y,z).move_to(vertices);
        }
      }
      for (unsigned int vv = 0; vv<subdivisions1; ++vv) {
        const unsigned int nv = (vv + 1)%subdivisions1;
        for (unsigned int uu = 0; uu<subdivisions2; ++uu) {
          const unsigned int nu = (uu + 1)%subdivisions2, svv = subdivisions2*vv, snv = subdivisions2*nv;
          CImg<tf>::vector(svv + nu,svv + uu,snv + uu,snv + nu).move_to(primitives);
        }
      }
      return vertices>'x';
    }

    //! Generate a 3D XY-plane.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param size_x The width of the plane (dimension along the X-axis).
       \param size_y The height of the plane (dimensions along the Y-axis).
       \param subdivisions_x The number of planar subdivisions along the X-axis.
       \param subdivisions_y The number of planar subdivisions along the Y-axis.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::plane3d(faces3d,100,50);
       CImg<unsigned char>().display_object3d("Plane3d",points3d,faces3d);
       \endcode
       \image html ref_plane3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> plane3d(CImgList<tf>& primitives,
                                const float size_x=100, const float size_y=100,
                                const unsigned int subdivisions_x=10, const unsigned int subdivisions_y=10) {
      primitives.assign();
      if (!subdivisions_x || !subdivisions_y) return CImg<floatT>();
      CImgList<floatT> vertices;
      const unsigned int w = subdivisions_x + 1, h = subdivisions_y + 1;
      const float fx = (float)size_x/w, fy = (float)size_y/h;
      for (unsigned int y = 0; y<h; ++y) for (unsigned int x = 0; x<w; ++x)
        CImg<floatT>::vector(fx*x,fy*y,0).move_to(vertices);
      for (unsigned int y = 0; y<subdivisions_y; ++y) for (unsigned int x = 0; x<subdivisions_x; ++x) {
        const int off1 = x + y*w, off2 = x + 1 + y*w, off3 = x + 1 + (y + 1)*w, off4 = x + (y + 1)*w;
        CImg<tf>::vector(off1,off4,off3,off2).move_to(primitives);
      }
      return vertices>'x';
    }

    //! Generate a 3D sphere.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param radius The radius of the sphere (dimension along the X-axis).
       \param subdivisions The number of recursive subdivisions from an initial icosahedron.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> points3d = CImg<float>::sphere3d(faces3d,100,4);
       CImg<unsigned char>().display_object3d("Sphere3d",points3d,faces3d);
       \endcode
       \image html ref_sphere3d.jpg
    **/
    template<typename tf>
    static CImg<floatT> sphere3d(CImgList<tf>& primitives,
                                 const float radius=50, const unsigned int subdivisions=3) {

      // Create initial icosahedron.
      primitives.assign();
      const double tmp = (1 + std::sqrt(5.f))/2, a = 1./std::sqrt(1 + tmp*tmp), b = tmp*a;
      CImgList<floatT> vertices = CImg<floatT>(1,12*3,1,1,
                                               b,a,0., -b,a,0., -b,-a,0., b,-a,0., a,0.,b, a,0.,-b,
                                               -a,0.,-b, -a,0.,b, 0.,b,a, 0.,-b,a, 0.,-b,-a, 0.,b,-a).get_split('y',12);
      CImg<floatT>(1,20*3,1,1,
                   4,8,7, 4,7,9, 5,6,11, 5,10,6, 0,4,3, 0,3,5, 2,7,1, 2,1,6, 8,0,11, 8,11,1,
                   9,10,3, 9,2,10, 8,4,0, 11,0,5, 4,9,3, 5,3,10, 7,8,1, 6,1,11, 7,2,9, 6,10,2).
        get_split('y',20).move_to(primitives);

      // edge - length/2.
      float he = (float)a;

      // Recurse subdivisions.
      for (unsigned int i = 0; i<subdivisions; ++i) {
        const unsigned int L = primitives._width;
        he/=2;
        const float he2 = he*he;
        for (unsigned int l = 0; l<L; ++l) {
          const unsigned int
            p0 = (unsigned int)primitives(0,0), p1 = (unsigned int)primitives(0,1), p2 = (unsigned int)primitives(0,2);
          const float
            x0 = vertices(p0,0), y0 = vertices(p0,1), z0 = vertices(p0,2),
            x1 = vertices(p1,0), y1 = vertices(p1,1), z1 = vertices(p1,2),
            x2 = vertices(p2,0), y2 = vertices(p2,1), z2 = vertices(p2,2),
            tnx0 = (x0 + x1)/2, tny0 = (y0 + y1)/2, tnz0 = (z0 + z1)/2,
            nn0 = cimg::hypot(tnx0,tny0,tnz0),
            tnx1 = (x0 + x2)/2, tny1 = (y0 + y2)/2, tnz1 = (z0 + z2)/2,
            nn1 = cimg::hypot(tnx1,tny1,tnz1),
            tnx2 = (x1 + x2)/2, tny2 = (y1 + y2)/2, tnz2 = (z1 + z2)/2,
            nn2 = cimg::hypot(tnx2,tny2,tnz2),
            nx0 = tnx0/nn0, ny0 = tny0/nn0, nz0 = tnz0/nn0,
            nx1 = tnx1/nn1, ny1 = tny1/nn1, nz1 = tnz1/nn1,
            nx2 = tnx2/nn2, ny2 = tny2/nn2, nz2 = tnz2/nn2;
          int i0 = -1, i1 = -1, i2 = -1;
          cimglist_for(vertices,p) {
            const float x = (float)vertices(p,0), y = (float)vertices(p,1), z = (float)vertices(p,2);
            if (cimg::sqr(x-nx0) + cimg::sqr(y-ny0) + cimg::sqr(z-nz0)<he2) i0 = p;
            if (cimg::sqr(x-nx1) + cimg::sqr(y-ny1) + cimg::sqr(z-nz1)<he2) i1 = p;
            if (cimg::sqr(x-nx2) + cimg::sqr(y-ny2) + cimg::sqr(z-nz2)<he2) i2 = p;
          }
          if (i0<0) { CImg<floatT>::vector(nx0,ny0,nz0).move_to(vertices); i0 = vertices.width() - 1; }
          if (i1<0) { CImg<floatT>::vector(nx1,ny1,nz1).move_to(vertices); i1 = vertices.width() - 1; }
          if (i2<0) { CImg<floatT>::vector(nx2,ny2,nz2).move_to(vertices); i2 = vertices.width() - 1; }
          primitives.remove(0);
          CImg<tf>::vector(p0,i0,i1).move_to(primitives);
          CImg<tf>::vector((tf)i0,(tf)p1,(tf)i2).move_to(primitives);
          CImg<tf>::vector((tf)i1,(tf)i2,(tf)p2).move_to(primitives);
          CImg<tf>::vector((tf)i1,(tf)i0,(tf)i2).move_to(primitives);
        }
      }
      return (vertices>'x')*=radius;
    }

    //! Generate a 3D ellipsoid.
    /**
       \param[out] primitives The returned list of the 3D object primitives
                              (template type \e tf should be at least \e unsigned \e int).
       \param tensor The tensor which gives the shape and size of the ellipsoid.
       \param subdivisions The number of recursive subdivisions from an initial stretched icosahedron.
       \return The N vertices (xi,yi,zi) of the 3D object as a Nx3 CImg<float> image (0<=i<=N - 1).
       \par Example
       \code
       CImgList<unsigned int> faces3d;
       const CImg<float> tensor = CImg<float>::diagonal(10,7,3),
                         points3d = CImg<float>::ellipsoid3d(faces3d,tensor,4);
       CImg<unsigned char>().display_object3d("Ellipsoid3d",points3d,faces3d);
       \endcode
       \image html ref_ellipsoid3d.jpg
    **/
    template<typename tf, typename t>
    static CImg<floatT> ellipsoid3d(CImgList<tf>& primitives,
                                    const CImg<t>& tensor, const unsigned int subdivisions=3) {
      primitives.assign();
      if (!subdivisions) return CImg<floatT>();
      CImg<floatT> S, V;
      tensor.symmetric_eigen(S,V);
      const float orient =
        (V(0,1)*V(1,2) - V(0,2)*V(1,1))*V(2,0) +
        (V(0,2)*V(1,0) - V(0,0)*V(1,2))*V(2,1) +
        (V(0,0)*V(1,1) - V(0,1)*V(1,0))*V(2,2);
      if (orient<0) { V(2,0) = -V(2,0); V(2,1) = -V(2,1); V(2,2) = -V(2,2); }
      const float l0 = S[0], l1 = S[1], l2 = S[2];
      CImg<floatT> vertices = sphere3d(primitives,1.,subdivisions);
      vertices.get_shared_row(0)*=l0;
      vertices.get_shared_row(1)*=l1;
      vertices.get_shared_row(2)*=l2;
      return V*vertices;
    }

    //! Convert 3D object into a CImg3d representation.
    /**
       \param primitives Primitives data of the 3D object.
       \param colors Colors data of the 3D object.
       \param opacities Opacities data of the 3D object.
       \param full_check Indicates whether full checking of the 3D object must be performed.
    **/
    template<typename tp, typename tc, typename to>
    CImg<T>& object3dtoCImg3d(const CImgList<tp>& primitives,
                              const CImgList<tc>& colors,
                              const to& opacities,
                              const bool full_check=true) {
      return get_object3dtoCImg3d(primitives,colors,opacities,full_check).move_to(*this);
    }

    //! Convert 3D object into a CImg3d representation \overload.
    template<typename tp, typename tc>
    CImg<T>& object3dtoCImg3d(const CImgList<tp>& primitives,
                              const CImgList<tc>& colors,
                              const bool full_check=true) {
      return get_object3dtoCImg3d(primitives,colors,full_check).move_to(*this);
    }

    //! Convert 3D object into a CImg3d representation \overload.
    template<typename tp>
    CImg<T>& object3dtoCImg3d(const CImgList<tp>& primitives,
                              const bool full_check=true) {
      return get_object3dtoCImg3d(primitives,full_check).move_to(*this);
    }

    //! Convert 3D object into a CImg3d representation \overload.
    CImg<T>& object3dtoCImg3d(const bool full_check=true) {
      return get_object3dtoCImg3d(full_check).move_to(*this);
    }

    //! Convert 3D object into a CImg3d representation \newinstance.
    template<typename tp, typename tc, typename to>
    CImg<floatT> get_object3dtoCImg3d(const CImgList<tp>& primitives,
                                      const CImgList<tc>& colors,
                                      const to& opacities,
                                      const bool full_check=true) const {
      CImg<charT> error_message(1024);
      if (!is_object3d(primitives,colors,opacities,full_check,error_message))
        throw CImgInstanceException(_cimg_instance
                                    "object3dtoCImg3d(): Invalid specified 3D object (%u,%u) (%s).",
                                    cimg_instance,_width,primitives._width,error_message.data());
      CImg<floatT> res(1,_size_object3dtoCImg3d(primitives,colors,opacities));
      float *ptrd = res._data;

      // Put magick number.
      *(ptrd++) = 'C' + 0.5f; *(ptrd++) = 'I' + 0.5f; *(ptrd++) = 'm' + 0.5f;
      *(ptrd++) = 'g' + 0.5f; *(ptrd++) = '3' + 0.5f; *(ptrd++) = 'd' + 0.5f;

      // Put number of vertices and primitives.
      *(ptrd++) = cimg::uint2float(_width,0.0f);
      *(ptrd++) = cimg::uint2float(primitives._width,0.0f);

      // Put vertex data.
      if (is_empty() || !primitives) return res;
      const T *ptrx = data(0,0), *ptry = data(0,1), *ptrz = data(0,2);
      cimg_forX(*this,p) {
        *(ptrd++) = (float)*(ptrx++);
        *(ptrd++) = (float)*(ptry++);
        *(ptrd++) = (float)*(ptrz++);
      }

      // Put primitive data.
      cimglist_for(primitives,p) {
        *(ptrd++) = (float)primitives[p].size();
        const tp *ptrp = primitives[p]._data;
        cimg_foroff(primitives[p],i) *(ptrd++) = cimg::uint2float((unsigned int)*(ptrp++),0.0f);
      }

      // Put color/texture data.
      const unsigned int csiz = std::min(colors._width,primitives._width);
      for (int c = 0; c<(int)csiz; ++c) {
        const CImg<tc>& color = colors[c];
        const tc *ptrc = color._data;
        if (color.size()==3) { *(ptrd++) = (float)*(ptrc++); *(ptrd++) = (float)*(ptrc++); *(ptrd++) = (float)*ptrc; }
        else {
          *(ptrd++) = -128.f;
          int shared_ind = -1;
          if (color.is_shared()) for (int i = 0; i<c; ++i) if (ptrc==colors[i]._data) { shared_ind = i; break; }
          if (shared_ind<0) {
            *(ptrd++) = (float)color._width;
            *(ptrd++) = (float)color._height;
            *(ptrd++) = (float)color._spectrum;
            cimg_foroff(color,l) *(ptrd++) = (float)*(ptrc++);
          } else {
            *(ptrd++) = cimg::uint2float((unsigned int)shared_ind,0.0f);
            *(ptrd++) = 0;
            *(ptrd++) = 0;
          }
        }
      }
      const int csiz2 = primitives.width() - colors.width();
      for (int c = 0; c<csiz2; ++c) { *(ptrd++) = 200.f; *(ptrd++) = 200.f; *(ptrd++) = 200.f; }

      // Put opacity data.
      ptrd = _object3dtoCImg3d(opacities,ptrd);
      const float *ptre = res.end();
      while (ptrd<ptre) *(ptrd++) = 1.f;
      return res;
    }

    template<typename to>
    float* _object3dtoCImg3d(const CImgList<to>& opacities, float *ptrd) const {
      cimglist_for(opacities,o) {
        const CImg<to>& opacity = opacities[o];
        const to *ptro = opacity._data;
        if (opacity.size()==1) *(ptrd++) = (float)*ptro;
        else {
          *(ptrd++) = -128.f;
          int shared_ind = -1;
          if (opacity.is_shared()) for (int i = 0; i<o; ++i) if (ptro==opacities[i]._data) { shared_ind = i; break; }
          if (shared_ind<0) {
            *(ptrd++) = (float)opacity._width;
            *(ptrd++) = (float)opacity._height;
            *(ptrd++) = (float)opacity._spectrum;
            cimg_foroff(opacity,l) *(ptrd++) = (float)*(ptro++);
          } else {
            *(ptrd++) = cimg::uint2float((unsigned int)shared_ind,0.0f);
            *(ptrd++) = 0;
            *(ptrd++) = 0;
          }
        }
      }
      return ptrd;
    }

    template<typename to>
    float* _object3dtoCImg3d(const CImg<to>& opacities, float *ptrd) const {
      const to *ptro = opacities._data;
      cimg_foroff(opacities,o) *(ptrd++) = (float)*(ptro++);
      return ptrd;
    }

    template<typename tp, typename tc, typename to>
    unsigned int _size_object3dtoCImg3d(const CImgList<tp>& primitives,
                                        const CImgList<tc>& colors,
                                        const CImgList<to>& opacities) const {
      unsigned int siz = 8U + 3*_width;
      cimglist_for(primitives,p) siz+=primitives[p].size() + 1;
      for (int c = std::min(primitives.width(),colors.width()) - 1; c>=0; --c) {
        if (colors[c].is_shared()) siz+=4;
        else { const unsigned int csiz = colors[c].size(); siz+=(csiz!=3)?4 + csiz:3; }
      }
      if (colors._width<primitives._width) siz+=3*(primitives._width - colors._width);
      cimglist_for(opacities,o) {
        if (opacities[o].is_shared()) siz+=4;
        else { const unsigned int osiz = opacities[o].size(); siz+=(osiz!=1)?4 + osiz:1; }
      }
      siz+=primitives._width - opacities._width;
      return siz;
    }

    template<typename tp, typename tc, typename to>
    unsigned int _size_object3dtoCImg3d(const CImgList<tp>& primitives,
                                        const CImgList<tc>& colors,
                                        const CImg<to>& opacities) const {
      unsigned int siz = 8U + 3*_width;
      cimglist_for(primitives,p) siz+=primitives[p].size() + 1;
      for (int c = std::min(primitives.width(),colors.width()) - 1; c>=0; --c) {
        const unsigned int csiz = colors[c].size(); siz+=(csiz!=3)?4 + csiz:3;
      }
      if (colors._width<primitives._width) siz+=3*(primitives._width - colors._width);
      siz+=primitives.size();
      cimg::unused(opacities);
      return siz;
    }

    //! Convert 3D object into a CImg3d representation \overload.
    template<typename tp, typename tc>
    CImg<floatT> get_object3dtoCImg3d(const CImgList<tp>& primitives,
                                      const CImgList<tc>& colors,
                                      const bool full_check=true) const {
      CImgList<T> opacities;
      return get_object3dtoCImg3d(primitives,colors,opacities,full_check);
    }

    //! Convert 3D object into a CImg3d representation \overload.
    template<typename tp>
    CImg<floatT> get_object3dtoCImg3d(const CImgList<tp>& primitives,
                                      const bool full_check=true) const {
      CImgList<T> colors, opacities;
      return get_object3dtoCImg3d(primitives,colors,opacities,full_check);
    }

    //! Convert 3D object into a CImg3d representation \overload.
    CImg<floatT> get_object3dtoCImg3d(const bool full_check=true) const {
      CImgList<T> opacities, colors;
      CImgList<uintT> primitives(width(),1,1,1,1);
      cimglist_for(primitives,p) primitives(p,0) = p;
      return get_object3dtoCImg3d(primitives,colors,opacities,full_check);
    }

    //! Convert CImg3d representation into a 3D object.
    /**
       \param[out] primitives Primitives data of the 3D object.
       \param[out] colors Colors data of the 3D object.
       \param[out] opacities Opacities data of the 3D object.
       \param full_check Indicates whether full checking of the 3D object must be performed.
    **/
    template<typename tp, typename tc, typename to>
    CImg<T>& CImg3dtoobject3d(CImgList<tp>& primitives,
                              CImgList<tc>& colors,
                              CImgList<to>& opacities,
                              const bool full_check=true) {
      return get_CImg3dtoobject3d(primitives,colors,opacities,full_check).move_to(*this);
    }

    //! Convert CImg3d representation into a 3D object \newinstance.
    template<typename tp, typename tc, typename to>
    CImg<T> get_CImg3dtoobject3d(CImgList<tp>& primitives,
                                 CImgList<tc>& colors,
                                 CImgList<to>& opacities,
                                 const bool full_check=true) const {
      CImg<charT> error_message(1024);
      if (!is_CImg3d(full_check,error_message))
        throw CImgInstanceException(_cimg_instance
                                    "CImg3dtoobject3d(): image instance is not a CImg3d (%s).",
                                    cimg_instance,error_message.data());
      const T *ptrs = _data + 6;
      const unsigned int
        nb_points = cimg::float2uint(*(ptrs++)),
        nb_primitives = cimg::float2uint(*(ptrs++));
      const CImg<T> points = CImg<T>(ptrs,3,nb_points,1,1,true).get_transpose();
      ptrs+=3*nb_points;
      primitives.assign(nb_primitives);
      cimglist_for(primitives,p) {
        const unsigned int nb_inds = (unsigned int)*(ptrs++);
        primitives[p].assign(1,nb_inds);
        tp *ptrp = primitives[p]._data;
        for (unsigned int i = 0; i<nb_inds; ++i)
          *(ptrp++) = (tp)cimg::float2uint(*(ptrs++));
      }
      colors.assign(nb_primitives);

      cimglist_for(colors,c) {
        if (*ptrs==(T)-128) {
          ++ptrs;
          const unsigned int
            w = (unsigned int)cimg::float2uint(*(ptrs++)),
            h = (unsigned int)*(ptrs++),
            s = (unsigned int)*(ptrs++);
          if (!h && !s) colors[c].assign(colors[w],true);
          else { colors[c].assign(ptrs,w,h,1,s,false); ptrs+=(ulongT)w*h*s; }
        } else { colors[c].assign(ptrs,1,1,1,3,false); ptrs+=3; }
      }
      opacities.assign(nb_primitives);
      cimglist_for(opacities,o) {
        if (*ptrs==(T)-128) {
          ++ptrs;
          const unsigned int
            w = (unsigned int)cimg::float2uint(*(ptrs++)),
            h = (unsigned int)*(ptrs++),
            s = (unsigned int)*(ptrs++);
          if (!h && !s) opacities[o].assign(opacities[w],true);
          else { opacities[o].assign(ptrs,w,h,1,s,false); ptrs+=(ulongT)w*h*s; }
        } else opacities[o].assign(1,1,1,1,*(ptrs++));
      }
      return points;
    }

    //@}
    //---------------------------
    //
    //! \name Drawing Functions
    //@{
    //---------------------------

#define cimg_init_scanline(opacity) \
    static const T _sc_maxval = (T)std::min(cimg::type<T>::max(),(T)cimg::type<tc>::max()); \
    const float _sc_nopacity = cimg::abs((float)opacity), _sc_copacity = 1 - std::max((float)opacity,0.f); \
    const ulongT _sc_whd = (ulongT)_width*_height*_depth; \
    cimg::unused(_sc_maxval);

#define cimg_draw_scanline(x0,x1,y,color,opacity,brightness) \
    _draw_scanline(x0,x1,y,color,opacity,brightness,_sc_nopacity,_sc_copacity,_sc_whd,_sc_maxval)

    // [internal] The following _draw_scanline() routines are *non user-friendly functions*,
    // used only for internal purpose.
    // Pre-requisites: x0<=x1, y-coordinate is valid, col is valid.
    template<typename tc>
    CImg<T>& _draw_scanline(const int x0, const int x1, const int y,
                            const tc *const color, const float opacity,
                            const float brightness,
                            const float nopacity, const float copacity, const ulongT whd, const T _sc_maxval) {
      const int nx0 = x0>0?x0:0, nx1 = x1<width()?x1:width() - 1, dx = nx1 - nx0;
      if (dx>=0) {
        const tc *col = color;
        const ulongT off = whd - dx - 1;
        T *ptrd = data(nx0,y);
        if (opacity>=1) { // ** Opaque drawing **
          if (brightness==1) { // Brightness==1
            if (sizeof(T)!=1) cimg_forC(*this,c) {
                const T val = (T)*(col++);
                for (int x = dx; x>=0; --x) *(ptrd++) = val;
                ptrd+=off;
              } else cimg_forC(*this,c) {
                const T val = (T)*(col++);
                std::memset(ptrd,(int)val,dx + 1);
                ptrd+=whd;
              }
          } else if (brightness<1) { // Brightness<1
            if (sizeof(T)!=1) cimg_forC(*this,c) {
                const T val = (T)(*(col++)*brightness);
                for (int x = dx; x>=0; --x) *(ptrd++) = val;
                ptrd+=off;
              } else cimg_forC(*this,c) {
                const T val = (T)(*(col++)*brightness);
                std::memset(ptrd,(int)val,dx + 1);
                ptrd+=whd;
              }
          } else { // Brightness>1
            if (sizeof(T)!=1) cimg_forC(*this,c) {
                const T val = (T)((2-brightness)**(col++) + (brightness - 1)*_sc_maxval);
                for (int x = dx; x>=0; --x) *(ptrd++) = val;
                ptrd+=off;
              } else cimg_forC(*this,c) {
                const T val = (T)((2-brightness)**(col++) + (brightness - 1)*_sc_maxval);
                std::memset(ptrd,(int)val,dx + 1);
                ptrd+=whd;
              }
          }
        } else { // ** Transparent drawing **
          if (brightness==1) { // Brightness==1
            cimg_forC(*this,c) {
              const Tfloat val = *(col++)*nopacity;
              for (int x = dx; x>=0; --x) { *ptrd = (T)(val + *ptrd*copacity); ++ptrd; }
              ptrd+=off;
            }
          } else if (brightness<=1) { // Brightness<1
            cimg_forC(*this,c) {
              const Tfloat val = *(col++)*brightness*nopacity;
              for (int x = dx; x>=0; --x) { *ptrd = (T)(val + *ptrd*copacity); ++ptrd; }
              ptrd+=off;
            }
          } else { // Brightness>1
            cimg_forC(*this,c) {
              const Tfloat val = ((2-brightness)**(col++) + (brightness - 1)*_sc_maxval)*nopacity;
              for (int x = dx; x>=0; --x) { *ptrd = (T)(val + *ptrd*copacity); ++ptrd; }
              ptrd+=off;
            }
          }
        }
      }
      return *this;
    }

    //! Draw a 3D point.
    /**
       \param x0 X-coordinate of the point.
       \param y0 Y-coordinate of the point.
       \param z0 Z-coordinate of the point.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \note
       - To set pixel values without clipping needs, you should use the faster CImg::operator()() function.
       \par Example:
       \code
       CImg<unsigned char> img(100,100,1,3,0);
       const unsigned char color[] = { 255,128,64 };
       img.draw_point(50,50,color);
       \endcode
    **/
    template<typename tc>
    CImg<T>& draw_point(const int x0, const int y0, const int z0,
                        const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_point(): Specified color is (null).",
                                    cimg_instance);
      if (x0>=0 && y0>=0 && z0>=0 && x0<width() && y0<height() && z0<depth()) {
        const ulongT whd = (ulongT)_width*_height*_depth;
        const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
        T *ptrd = data(x0,y0,z0,0);
        const tc *col = color;
        if (opacity>=1) cimg_forC(*this,c) { *ptrd = (T)*(col++); ptrd+=whd; }
        else cimg_forC(*this,c) { *ptrd = (T)(*(col++)*nopacity + *ptrd*copacity); ptrd+=whd; }
      }
      return *this;
    }

    //! Draw a 2D point \overload.
    template<typename tc>
    CImg<T>& draw_point(const int x0, const int y0,
                        const tc *const color, const float opacity=1) {
      return draw_point(x0,y0,0,color,opacity);
    }

    // Draw a point cloud.
    /**
       \param points Image of vertices coordinates.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename t, typename tc>
    CImg<T>& draw_point(const CImg<t>& points,
                        const tc *const color, const float opacity=1) {
      if (is_empty() || !points) return *this;
      switch (points._height) {
      case 0 : case 1 :
        throw CImgArgumentException(_cimg_instance
                                    "draw_point(): Invalid specified point set (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum,points._data);
      case 2 : {
        cimg_forX(points,i) draw_point((int)points(i,0),(int)points(i,1),color,opacity);
      } break;
      default : {
        cimg_forX(points,i) draw_point((int)points(i,0),(int)points(i,1),(int)points(i,2),color,opacity);
      }
      }
      return *this;
    }

    //! Draw a 2D line.
    /**
       \param x0 X-coordinate of the starting line point.
       \param y0 Y-coordinate of the starting line point.
       \param x1 X-coordinate of the ending line point.
       \param y1 Y-coordinate of the ending line point.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
       \param draw_last_pixel Indicates whether last pixel of the line must be drawn (e.g. can be disabled
       when drawing multi-line curves with transparency).
       \note
       - Set \p init_hatch = false to draw consecutive hatched segments without breaking the line stipple pattern.
       \par Example:
       \code
       CImg<unsigned char> img(100,100,1,3,0);
       const unsigned char color[] = { 255,128,64 };
        img.draw_line(40,40,80,70,color);
       \endcode
    **/
    template<typename tc>
    CImg<T>& draw_line(int x0, int y0,
                       int x1, int y1,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true,
                       const bool draw_last_pixel=true) {
      if (is_empty() || !opacity || !pattern ||
          std::min(y0,y1)>=height() || std::max(y0,y1)<0 || std::min(x0,x1)>=width() || std::max(x0,x1)<0)
        return *this;
      if (x0==x1 && y0==y1) return draw_point(x0,y0,0,color,opacity);
      int w1 = width() - 1, h1 = height() - 1, x01 = x1 - x0, y01 = y1 - y0;
      const bool is_horizontal = cimg::abs(x01)>cimg::abs(y01);
      if (is_horizontal) cimg::swap(x0,y0,x1,y1,w1,h1,x01,y01);

      const int dy = std::max(1,cimg::abs(y01)), hdy = dy/2;
      static unsigned int hatch = ~0U - (~0U>>1);
      if (init_hatch) hatch = ~0U - (~0U>>1);

      cimg_init_scanline(opacity);

      const int
        step = y0<=y1?1:-1,
        y0_cut = cimg::cut(y0,0,h1),
        y1_cut = cimg::cut(y1,0,h1) + (draw_last_pixel?step:0);

      for (int y = y0_cut; y!=y1_cut; y+=step) {
        const int
          t = cimg::abs(y - y0),
          x = x0 + cimg_rd(t,x01,dy);
        if (x>=0 && x<=w1 && pattern&hatch) {
          T *const ptrd = is_horizontal?data(y,x):data(x,y);
          cimg_forC(*this,c) {
            const T val = color[c];
            ptrd[c*_sc_whd] = opacity>=1?val:(T)(val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
          }
        }
        if (!(hatch>>=1)) hatch = ~0U - (~0U>>1);
      }
      return *this;
    }

    //! Draw a 2D line, with z-buffering.
    /**
       \param zbuffer Zbuffer image.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param z0 Z-coordinate of the starting point
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param z1 Z-coordinate of the ending point.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
    **/
    template<typename tz, typename tc>
    CImg<T>& draw_line(CImg<tz>& zbuffer,
                       int x0, int y0, const float z0,
                       int x1, int y1, const float z1,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || z0<=0 || z1<=0 || !opacity || !pattern) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Specified color is (null).",
                                    cimg_instance);
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);

      if (std::min(y0,y1)>=height() || std::max(y0,y1)<0 || std::min(x0,x1)>=width() || std::max(x0,x1)<0)
        return *this;
      int
        w1 = width() - 1, h1 = height() - 1,
        dx01 = x1 - x0, dy01 = y1 - y0;
      float iz0 = 1/z0, iz1 = 1/z1, diz01 = iz1 - iz0;

      const bool is_horizontal = cimg::abs(dx01)>cimg::abs(dy01);
      if (is_horizontal) cimg::swap(x0,y0,x1,y1,w1,h1,dx01,dy01);
      if (pattern==~0U && y0>y1) {
        cimg::swap(x0,x1,y0,y1,iz0,iz1);
        dx01*=-1; dy01*=-1; diz01*=-1;
      }
      const float
        slope_x = dy01?(float)dx01/dy01:0,
        slope_iz = dy01?(float)diz01/dy01:0;

      static unsigned int hatch = ~0U - (~0U>>1);
      if (init_hatch) hatch = ~0U - (~0U>>1);
      cimg_init_scanline(opacity);

      const int step = y0<=y1?1:-1, cy0 = cimg::cut(y0,0,h1), cy1 = cimg::cut(y1,0,h1) + step;
      dy01+=dy01?0:1;

      for (int y = cy0; y!=cy1; y+=step) {
        const int yy0 = y - y0;
        const float
          fx = x0 + yy0*slope_x,
          iz = iz0 + yy0*slope_iz;
        if (fx>=0 && fx<=w1 && pattern&hatch) {
          const int x = (int)(fx + 0.5f);
          tz *const ptrz = is_horizontal?zbuffer.data(y,x):zbuffer.data(x,y);
          if (iz>=*ptrz) {
            *ptrz = (tz)iz;
            T *const ptrd = is_horizontal?data(y,x):data(x,y);
            cimg_forC(*this,c) {
              const T val = color[c];
              ptrd[c*_sc_whd] = opacity>=1?val:(T)(val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
          }
        }
        if (!(hatch>>=1)) hatch = ~0U - (~0U>>1);
      }
      return *this;
    }

    //! Draw a textured 2D line.
    /**
       \param x0 X-coordinate of the starting line point.
       \param y0 Y-coordinate of the starting line point.
       \param x1 X-coordinate of the ending line point.
       \param y1 Y-coordinate of the ending line point.
       \param texture Texture image defining the pixel colors.
       \param tx0 X-coordinate of the starting texture point.
       \param ty0 Y-coordinate of the starting texture point.
       \param tx1 X-coordinate of the ending texture point.
       \param ty1 Y-coordinate of the ending texture point.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
       \note
       - Line routine uses the well known Bresenham's algorithm.
       \par Example:
       \code
       CImg<unsigned char> img(100,100,1,3,0), texture("texture256x256.ppm");
       const unsigned char color[] = { 255,128,64 };
       img.draw_line(40,40,80,70,texture,0,0,255,255);
       \endcode
    **/
    template<typename tc>
    CImg<T>& draw_line(int x0, int y0,
                       int x1, int y1,
                       const CImg<tc>& texture,
                       int tx0, int ty0,
                       int tx1, int ty1,
                       const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true) {

      if (is_empty() || !opacity || !pattern) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture)) return draw_line(x0,y0,x1,y1,+texture,tx0,ty0,tx1,ty1,opacity,pattern,init_hatch);
      if (std::min(y0,y1)>=height() || std::max(y0,y1)<0 || std::min(x0,x1)>=width() || std::max(x0,x1)<0)
        return *this;
      int
        w1 = width() - 1, h1 = height() - 1,
        dx01 = x1 - x0, dy01 = y1 - y0,
        dtx01 = tx1 - tx0, dty01 = ty1 - ty0;

      const bool is_horizontal = cimg::abs(dx01)>cimg::abs(dy01);
      if (is_horizontal) cimg::swap(x0,y0,x1,y1,w1,h1,dx01,dy01);
      if (pattern==~0U && y0>y1) {
        cimg::swap(x0,x1,y0,y1,tx0,tx1,ty0,ty1);
        dx01*=-1; dy01*=-1; dtx01*=-1; dty01*=-1;
      }
      const float
        slope_x = dy01?(float)dx01/dy01:0,
        slope_tx = dy01?(float)dtx01/dy01:0,
        slope_ty = dy01?(float)dty01/dy01:0;

      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      static unsigned int hatch = ~0U - (~0U>>1);
      if (init_hatch) hatch = ~0U - (~0U>>1);
      cimg_init_scanline(opacity);

      const int step = y0<=y1?1:-1, cy0 = cimg::cut(y0,0,h1), cy1 = cimg::cut(y1,0,h1) + step;
      dy01+=dy01?0:1;

      for (int y = cy0; y!=cy1; y+=step) {
        const int yy0 = y - y0;
        const float
          fx = x0 + yy0*slope_x,
          ftx = tx0 + yy0*slope_tx,
          fty = ty0 + yy0*slope_ty;
        if (fx>=0 && fx<=w1 && pattern&hatch) {
          const int
            x = (int)(fx + 0.5f),
            tx = (int)ftx,
            ty = (int)fty;
          T *const ptrd = is_horizontal?data(y,x):data(x,y);
          const tc *const color = &texture._atXY(tx,ty);
          cimg_forC(*this,c) {
            const T val = color[c*twhd];
            ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
          }
        }
        if (!(hatch>>=1)) hatch = ~0U - (~0U>>1);
      }
      return *this;
    }

    //! Draw a textured 2D line, with perspective correction.
    /**
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param z0 Z-coordinate of the starting point
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param z1 Z-coordinate of the ending point.
       \param texture Texture image defining the pixel colors.
       \param tx0 X-coordinate of the starting texture point.
       \param ty0 Y-coordinate of the starting texture point.
       \param tx1 X-coordinate of the ending texture point.
       \param ty1 Y-coordinate of the ending texture point.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
    **/
    template<typename tc>
    CImg<T>& draw_line(int x0, int y0, const float z0,
                       int x1, int y1, const float z1,
                       const CImg<tc>& texture,
                       const int tx0, const int ty0,
                       const int tx1, const int ty1,
                       const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || z0<=0 || z1<=0 || !opacity || !pattern) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_line(x0,y0,z0,x1,y1,z1,+texture,tx0,ty0,tx1,ty1,opacity,pattern,init_hatch);
      if (std::min(y0,y1)>=height() || std::max(y0,y1)<0 || std::min(x0,x1)>=width() || std::max(x0,x1)<0)
        return *this;
      int
        w1 = width() - 1, h1 = height() - 1,
        dx01 = x1 - x0, dy01 = y1 - y0;
      float
        iz0 = 1/z0, iz1 = 1/z1,
        diz01 = iz1 - iz0,
        txz0 = tx0*iz0, txz1 = tx1*iz1,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1,
        dtxz01 = txz1 - txz0, dtyz01 = tyz1 - tyz0;

      const bool is_horizontal = cimg::abs(dx01)>cimg::abs(dy01);
      if (is_horizontal) cimg::swap(x0,y0,x1,y1,w1,h1,dx01,dy01);
      if (pattern==~0U && y0>y1) {
        cimg::swap(x0,x1,y0,y1,iz0,iz1,txz0,txz1,tyz0,tyz1);
        dx01*=-1; dy01*=-1; diz01*=-1; dtxz01*=-1; dtyz01*=-1;
      }
      const float
        slope_x = dy01?(float)dx01/dy01:0,
        slope_iz = dy01?(float)diz01/dy01:0,
        slope_txz = dy01?(float)dtxz01/dy01:0,
        slope_tyz = dy01?(float)dtyz01/dy01:0;

      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      static unsigned int hatch = ~0U - (~0U>>1);
      if (init_hatch) hatch = ~0U - (~0U>>1);
      cimg_init_scanline(opacity);

      const int step = y0<=y1?1:-1, cy0 = cimg::cut(y0,0,h1), cy1 = cimg::cut(y1,0,h1) + step;
      dy01+=dy01?0:1;

      for (int y = cy0; y!=cy1; y+=step) {
        const int yy0 = y - y0;
        const float
          fx = x0 + yy0*slope_x,
          iz = iz0 + yy0*slope_iz,
          ftxz = txz0 + yy0*slope_txz,
          ftyz = tyz0 + yy0*slope_tyz;
        if (fx>=0 && fx<=w1 && pattern&hatch) {
          const int
            x = (int)(fx + 0.5f),
            tx = (int)(ftxz/iz),
            ty = (int)(ftyz/iz);
          T *const ptrd = is_horizontal?data(y,x):data(x,y);
          const tc *const color = &texture._atXY(tx,ty);
          cimg_forC(*this,c) {
            const T val = color[c*twhd];
            ptrd[c*_sc_whd] = opacity>=1?val:(T)(val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
          }
        }
        if (!(hatch>>=1)) hatch = ~0U - (~0U>>1);
      }
      return *this;
    }

    //! Draw a textured 2D line, with perspective correction and z-buffering.
    /**
       \param zbuffer Z-buffer image.
       \param x0 X-coordinate of the starting point.
       \param y0 Y-coordinate of the starting point.
       \param z0 Z-coordinate of the starting point
       \param x1 X-coordinate of the ending point.
       \param y1 Y-coordinate of the ending point.
       \param z1 Z-coordinate of the ending point.
       \param texture Texture image defining the pixel colors.
       \param tx0 X-coordinate of the starting texture point.
       \param ty0 Y-coordinate of the starting texture point.
       \param tx1 X-coordinate of the ending texture point.
       \param ty1 Y-coordinate of the ending texture point.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
    **/
    template<typename tz, typename tc>
    CImg<T>& draw_line(CImg<tz>& zbuffer,
                       int x0, int y0, const float z0,
                       int x1, int y1, const float z1,
                       const CImg<tc>& texture,
                       const int tx0, const int ty0,
                       const int tx1, const int ty1,
                       const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || z0<=0 || z1<=0 || !opacity || !pattern) return *this;
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_line(zbuffer,x0,y0,z0,x1,y1,z1,+texture,tx0,ty0,tx1,ty1,opacity,pattern,init_hatch);
      if (std::min(y0,y1)>=height() || std::max(y0,y1)<0 || std::min(x0,x1)>=width() || std::max(x0,x1)<0)
        return *this;

      int
        w1 = width() - 1, h1 = height() - 1,
        dx01 = x1 - x0, dy01 = y1 - y0;
      float
        iz0 = 1/z0, iz1 = 1/z1,
        diz01 = iz1 - iz0,
        txz0 = tx0*iz0, txz1 = tx1*iz1,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1,
        dtxz01 = txz1 - txz0, dtyz01 = tyz1 - tyz0;

      const bool is_horizontal = cimg::abs(dx01)>cimg::abs(dy01);
      if (is_horizontal) cimg::swap(x0,y0,x1,y1,w1,h1,dx01,dy01);
      if (pattern==~0U && y0>y1) {
        cimg::swap(x0,x1,y0,y1,iz0,iz1,txz0,txz1,tyz0,tyz1);
        dx01*=-1; dy01*=-1; diz01*=-1; dtxz01*=-1; dtyz01*=-1;
      }
      const float
        slope_x = dy01?(float)dx01/dy01:0,
        slope_iz = dy01?(float)diz01/dy01:0,
        slope_txz = dy01?(float)dtxz01/dy01:0,
        slope_tyz = dy01?(float)dtyz01/dy01:0;

      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      static unsigned int hatch = ~0U - (~0U>>1);
      if (init_hatch) hatch = ~0U - (~0U>>1);
      cimg_init_scanline(opacity);

      const int step = y0<=y1?1:-1, cy0 = cimg::cut(y0,0,h1), cy1 = cimg::cut(y1,0,h1) + step;
      dy01+=dy01?0:1;

      for (int y = cy0; y!=cy1; y+=step) {
        const int yy0 = y - y0;
        const float
          fx = x0 + yy0*slope_x,
          iz = iz0 + yy0*slope_iz,
          ftxz = txz0 + yy0*slope_txz,
          ftyz = tyz0 + yy0*slope_tyz;
        if (fx>=0 && fx<=w1 && pattern&hatch) {
          const int x = (int)(fx + 0.5f);
          tz *const ptrz = is_horizontal?zbuffer.data(y,x):zbuffer.data(x,y);
          if (iz>=*ptrz) {
            *ptrz = (tz)iz;
            const int
              tx = (int)(ftxz/iz),
              ty = (int)(ftyz/iz);
            T *const ptrd = is_horizontal?data(y,x):data(x,y);
            const tc *const color = &texture._atXY(tx,ty);
            cimg_forC(*this,c) {
              const T val = color[c*twhd];
              ptrd[c*_sc_whd] = opacity>=1?val:(T)(val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
          }
        }
        if (!(hatch>>=1)) hatch = ~0U - (~0U>>1);
      }
      return *this;
    }

    //! Draw a polyline.
    /**
       \param points Coordinates of vertices, stored as a list of vectors.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
       \note
       - This function uses several call to the single CImg::draw_line() procedure,
       depending on the vectors size in \p points.
    **/
    template<typename tp, typename tc>
    CImg<T>& draw_line(const CImg<tp>& points,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || !points) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Specified color is (null).",
                                    cimg_instance);
      if (points.height()!=2)
        throw CImgArgumentException(_cimg_instance
                                    "draw_line(): Invalid specified point set (%u,%u,%u,%u).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum);
      CImg<intT> ipoints;
      if (cimg::type<tp>::is_float()) ipoints = points.get_round();
      else ipoints.assign(points,cimg::type<tp>::string()==cimg::type<int>::string());

      bool ninit_hatch = init_hatch;
      const int x0 = ipoints(0,0), y0 = ipoints(0,1);
      int ox = x0, oy = y0;
      for (unsigned int i = 1; i<ipoints._width; ++i) {
        const int x = ipoints(i,0), y = ipoints(i,1);
        draw_line(ox,oy,x,y,color,opacity,pattern,ninit_hatch);
        ninit_hatch = false;
        ox = x; oy = y;
      }
      return *this;
    }

    //! Draw a 2D arrow.
    /**
       \param x0 X-coordinate of the starting arrow point (tail).
       \param y0 Y-coordinate of the starting arrow point (tail).
       \param x1 X-coordinate of the ending arrow point (head).
       \param y1 Y-coordinate of the ending arrow point (head).
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param angle Aperture angle of the arrow head.
       \param length Length of the arrow head. If negative, describes a percentage of the arrow length.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
    **/
    template<typename tc>
    CImg<T>& draw_arrow(const int x0, const int y0,
                        const int x1, const int y1,
                        const tc *const color, const float opacity=1,
                        const float angle=30, const float length=-10,
                        const unsigned int pattern=~0U) {
      if (is_empty()) return *this;
      const float u = (float)(x0 - x1), v = (float)(y0 - y1), sq = u*u + v*v,
        deg = (float)(angle*cimg::PI/180), ang = (sq>0)?(float)std::atan2(v,u):0.f,
        l = (length>=0)?length:-length*(float)std::sqrt(sq)/100;
      if (sq>0) {
        const float
            cl = (float)std::cos(ang - deg), sl = (float)std::sin(ang - deg),
            cr = (float)std::cos(ang + deg), sr = (float)std::sin(ang + deg);
        const int
          xl = x1 + (int)(l*cl), yl = y1 + (int)(l*sl),
          xr = x1 + (int)(l*cr), yr = y1 + (int)(l*sr),
          xc = x1 + (int)((l + 1)*(cl + cr))/2, yc = y1 + (int)((l + 1)*(sl + sr))/2;
        draw_line(x0,y0,xc,yc,color,opacity,pattern).draw_triangle(x1,y1,xl,yl,xr,yr,color,opacity);
      } else draw_point(x0,y0,color,opacity);
      return *this;
    }

    //! Draw a 2D spline.
    /**
       \param x0 X-coordinate of the starting curve point
       \param y0 Y-coordinate of the starting curve point
       \param u0 X-coordinate of the starting velocity
       \param v0 Y-coordinate of the starting velocity
       \param x1 X-coordinate of the ending curve point
       \param y1 Y-coordinate of the ending curve point
       \param u1 X-coordinate of the ending velocity
       \param v1 Y-coordinate of the ending velocity
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param precision Curve drawing precision.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
       \note
       - The curve is a 2D cubic Bezier spline, from the set of specified starting/ending points
       and corresponding velocity vectors.
       - The spline is drawn as a sequence of connected segments. The \p precision parameter sets the
       average number of pixels in each drawn segment.
       - A cubic Bezier curve is sometimes defined by a set of 4 points { (\p x0,\p y0), (\p xa,\p ya),
         (\p xb,\p yb), (\p x1,\p y1) } where (\p x0,\p y0) is the starting point, (\p x1,\p y1) is the ending point
         and (\p xa,\p ya), (\p xb,\p yb) are two
       \e control points.
       The starting and ending velocities (\p u0,\p v0) and (\p u1,\p v1) can be deduced easily from
       the control points as
       \p u0 = (\p xa - \p x0), \p v0 = (\p ya - \p y0), \p u1 = (\p x1 - \p xb) and \p v1 = (\p y1 - \p yb).
       \par Example:
       \code
       CImg<unsigned char> img(100,100,1,3,0);
       const unsigned char color[] = { 255,255,255 };
       img.draw_spline(30,30,0,100,90,40,0,-100,color);
       \endcode
    **/
    template<typename tc>
    CImg<T>& draw_spline(const int x0, const int y0, const float u0, const float v0,
                         const int x1, const int y1, const float u1, const float v1,
                         const tc *const color, const float opacity=1,
                         const float precision=0.25f, const unsigned int pattern=~0U,
                         const bool init_hatch=true) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_spline(): Specified color is (null).",
                                    cimg_instance);
      if (x0==x1 && y0==y1) return draw_point(x0,y0,color,opacity);
      bool ninit_hatch = init_hatch;
      const float
        ax = u0 + u1 + 2*(x0 - x1),
        bx = 3*(x1 - x0) - 2*u0 - u1,
        ay = v0 + v1 + 2*(y0 - y1),
        by = 3*(y1 - y0) - 2*v0 - v1,
        _precision = 1/(cimg::hypot((float)x0 - x1,(float)y0 - y1)*(precision>0?precision:1));
      int ox = x0, oy = y0;
      for (float t = 0; t<1; t+=_precision) {
        const float t2 = t*t, t3 = t2*t;
        const int
          nx = (int)(ax*t3 + bx*t2 + u0*t + x0),
          ny = (int)(ay*t3 + by*t2 + v0*t + y0);
        draw_line(ox,oy,nx,ny,color,opacity,pattern,ninit_hatch);
        ninit_hatch = false;
        ox = nx; oy = ny;
      }
      return draw_line(ox,oy,x1,y1,color,opacity,pattern,false);
    }

    //! Draw a textured 2D spline.
    /**
       \param x0 X-coordinate of the starting curve point
       \param y0 Y-coordinate of the starting curve point
       \param u0 X-coordinate of the starting velocity
       \param v0 Y-coordinate of the starting velocity
       \param x1 X-coordinate of the ending curve point
       \param y1 Y-coordinate of the ending curve point
       \param u1 X-coordinate of the ending velocity
       \param v1 Y-coordinate of the ending velocity
       \param texture Texture image defining line pixel colors.
       \param tx0 X-coordinate of the starting texture point.
       \param ty0 Y-coordinate of the starting texture point.
       \param tx1 X-coordinate of the ending texture point.
       \param ty1 Y-coordinate of the ending texture point.
       \param precision Curve drawing precision.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
    **/
    template<typename t>
    CImg<T>& draw_spline(const int x0, const int y0, const float u0, const float v0,
                         const int x1, const int y1, const float u1, const float v1,
                         const CImg<t>& texture,
                         const int tx0, const int ty0, const int tx1, const int ty1,
                         const float opacity=1,
                         const float precision=4, const unsigned int pattern=~0U,
                         const bool init_hatch=true) {
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_spline(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_empty()) return *this;
      if (is_overlapped(texture))
        return draw_spline(x0,y0,u0,v0,x1,y1,u1,v1,+texture,tx0,ty0,tx1,ty1,opacity,precision,pattern,init_hatch);
      if (x0==x1 && y0==y1)
        return draw_point(x0,y0,texture.get_vector_at(x0<=0?0:x0>=texture.width()?texture.width() - 1:x0,
                                                      y0<=0?0:y0>=texture.height()?texture.height() - 1:y0).data(),
                          opacity);
      bool ninit_hatch = init_hatch;
      const float
        ax = u0 + u1 + 2*(x0 - x1),
        bx = 3*(x1 - x0) - 2*u0 - u1,
        ay = v0 + v1 + 2*(y0 - y1),
        by = 3*(y1 - y0) - 2*v0 - v1,
        _precision = 1/(cimg::hypot((float)x0 - x1,(float)y0 - y1)*(precision>0?precision:1));
      int ox = x0, oy = y0, otx = tx0, oty = ty0;
      for (float t1 = 0; t1<1; t1+=_precision) {
        const float t2 = t1*t1, t3 = t2*t1;
        const int
          nx = (int)(ax*t3 + bx*t2 + u0*t1 + x0),
          ny = (int)(ay*t3 + by*t2 + v0*t1 + y0),
          ntx = tx0 + (int)((tx1 - tx0)*t1),
          nty = ty0 + (int)((ty1 - ty0)*t1);
        draw_line(ox,oy,nx,ny,texture,otx,oty,ntx,nty,opacity,pattern,ninit_hatch);
        ninit_hatch = false;
        ox = nx; oy = ny; otx = ntx; oty = nty;
      }
      return draw_line(ox,oy,x1,y1,texture,otx,oty,tx1,ty1,opacity,pattern,false);
    }

    //! Draw a set of consecutive splines.
    /**
       \param points Vertices data.
       \param tangents Tangents data.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param is_closed_set Indicates whether the drawn spline set is closed.
       \param precision Precision of the drawing.
       \param pattern An integer whose bits describe the line stipple pattern.
       \param init_hatch Indicates whether the hatch variable must be reinitialized.
    **/
    template<typename tp, typename tt, typename tc>
    CImg<T>& draw_spline(const CImg<tp>& points, const CImg<tt>& tangents,
                         const tc *const color, const float opacity=1,
                         const bool is_closed_set=false, const float precision=4,
                         const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || !points || !tangents || points._width<2 || tangents._width<2) return *this;
      bool ninit_hatch = init_hatch;
      switch (points._height) {
      case 0 : case 1 :
        throw CImgArgumentException(_cimg_instance
                                    "draw_spline(): Invalid specified point set (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum,points._data);

      default : {
        const int x0 = (int)points(0,0), y0 = (int)points(0,1);
        const float u0 = (float)tangents(0,0), v0 = (float)tangents(0,1);
        int ox = x0, oy = y0;
        float ou = u0, ov = v0;
        for (unsigned int i = 1; i<points._width; ++i) {
          const int x = (int)points(i,0), y = (int)points(i,1);
          const float u = (float)tangents(i,0), v = (float)tangents(i,1);
          draw_spline(ox,oy,ou,ov,x,y,u,v,color,opacity,precision,pattern,ninit_hatch);
          ninit_hatch = false;
          ox = x; oy = y; ou = u; ov = v;
        }
        if (is_closed_set) draw_spline(ox,oy,ou,ov,x0,y0,u0,v0,color,opacity,precision,pattern,false);
      }
      }
      return *this;
    }

    //! Draw a set of consecutive splines \overload.
    /**
       Similar to previous function, with the point tangents automatically estimated from the given points set.
    **/
    template<typename tp, typename tc>
    CImg<T>& draw_spline(const CImg<tp>& points,
                         const tc *const color, const float opacity=1,
                         const bool is_closed_set=false, const float precision=4,
                         const unsigned int pattern=~0U, const bool init_hatch=true) {
      if (is_empty() || !points || points._width<2) return *this;
      CImg<Tfloat> tangents;
      switch (points._height) {
      case 0 : case 1 :
        throw CImgArgumentException(_cimg_instance
                                    "draw_spline(): Invalid specified point set (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum,points._data);
      case 2 : {
        tangents.assign(points._width,points._height);
        cimg_forX(points,p) {
          const unsigned int
            p0 = is_closed_set?(p + points.width() - 1)%points.width():(p?p - 1:0),
            p1 = is_closed_set?(p + 1)%points.width():(p + 1<points.width()?p + 1:p);
          const float
            x = (float)points(p,0),
            y = (float)points(p,1),
            x0 = (float)points(p0,0),
            y0 = (float)points(p0,1),
            x1 = (float)points(p1,0),
            y1 = (float)points(p1,1),
            u0 = x - x0,
            v0 = y - y0,
            n0 = 1e-8f + cimg::hypot(u0,v0),
            u1 = x1 - x,
            v1 = y1 - y,
            n1 = 1e-8f + cimg::hypot(u1,v1),
            u = u0/n0 + u1/n1,
            v = v0/n0 + v1/n1,
            n = 1e-8f + cimg::hypot(u,v),
            fact = 0.5f*(n0 + n1);
          tangents(p,0) = (Tfloat)(fact*u/n);
          tangents(p,1) = (Tfloat)(fact*v/n);
        }
      } break;
      default : {
        tangents.assign(points._width,points._height);
        cimg_forX(points,p) {
          const unsigned int
            p0 = is_closed_set?(p + points.width() - 1)%points.width():(p?p - 1:0),
            p1 = is_closed_set?(p + 1)%points.width():(p + 1<points.width()?p + 1:p);
          const float
            x = (float)points(p,0),
            y = (float)points(p,1),
            z = (float)points(p,2),
            x0 = (float)points(p0,0),
            y0 = (float)points(p0,1),
            z0 = (float)points(p0,2),
            x1 = (float)points(p1,0),
            y1 = (float)points(p1,1),
            z1 = (float)points(p1,2),
            u0 = x - x0,
            v0 = y - y0,
            w0 = z - z0,
            n0 = 1e-8f + cimg::hypot(u0,v0,w0),
            u1 = x1 - x,
            v1 = y1 - y,
            w1 = z1 - z,
            n1 = 1e-8f + cimg::hypot(u1,v1,w1),
            u = u0/n0 + u1/n1,
            v = v0/n0 + v1/n1,
            w = w0/n0 + w1/n1,
            n = 1e-8f + cimg::hypot(u,v,w),
            fact = 0.5f*(n0 + n1);
          tangents(p,0) = (Tfloat)(fact*u/n);
          tangents(p,1) = (Tfloat)(fact*v/n);
          tangents(p,2) = (Tfloat)(fact*w/n);
        }
      }
      }
      return draw_spline(points,tangents,color,opacity,is_closed_set,precision,pattern,init_hatch);
    }

    // [internal] Draw a filled triangle.
    template<typename tc>
    CImg<T>& _draw_triangle(int x0, int y0,
                            int x1, int y1,
                            int x2, int y2,
                            const tc *const color, const float opacity,
                            const float brightness) {
      if (y0>y1) cimg::swap(x0,x1,y0,y1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0,
        dx02 = (longT)x2 - x0,
        dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float cbs = cimg::cut(brightness,0.f,2.f);

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        if (xm>xM) cimg::swap(xm,xM);
        cimg_draw_scanline(xm,xM,y,color,opacity,cbs);
      }
      return *this;
    }

    //! Draw a filled 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex.
       \param y0 Y-coordinate of the first vertex.
       \param x1 X-coordinate of the second vertex.
       \param y1 Y-coordinate of the second vertex.
       \param x2 X-coordinate of the third vertex.
       \param y2 Y-coordinate of the third vertex.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
     **/
    template<typename tc>
    CImg<T>& draw_triangle(const int x0, const int y0,
                           const int x1, const int y1,
                           const int x2, const int y2,
                           const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      _draw_triangle(x0,y0,x1,y1,x2,y2,color,opacity,1);
      return *this;
    }

    //! Draw a outlined 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex.
       \param y0 Y-coordinate of the first vertex.
       \param x1 X-coordinate of the second vertex.
       \param y1 Y-coordinate of the second vertex.
       \param x2 X-coordinate of the third vertex.
       \param y2 Y-coordinate of the third vertex.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the outline stipple pattern.
     **/
    template<typename tc>
    CImg<T>& draw_triangle(const int x0, const int y0,
                           const int x1, const int y1,
                           const int x2, const int y2,
                           const tc *const color, const float opacity,
                           const unsigned int pattern) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      CImg<intT> points(3,2,1,1,x0,x1,x2,y0,y1,y2);
      return draw_polygon(points,color,opacity,pattern);
    }

    //! Draw a filled 2D triangle, with z-buffering.
    /**
       \param zbuffer Z-buffer image.
       \param x0 X-coordinate of the first vertex.
       \param y0 Y-coordinate of the first vertex.
       \param z0 Z-coordinate of the first vertex.
       \param x1 X-coordinate of the second vertex.
       \param y1 Y-coordinate of the second vertex.
       \param z1 Z-coordinate of the second vertex.
       \param x2 X-coordinate of the third vertex.
       \param y2 Y-coordinate of the third vertex.
       \param z2 Z-coordinate of the third vertex.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
       \param brightness Brightness factor.
    **/
    template<typename tz, typename tc>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const tc *const color, const float opacity=1,
                           const float brightness=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        cbs = cimg::cut(brightness,0.f,2.f);

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,izm,izM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              cimg_forC(*this,c) {
                const Tfloat val = cbs<=1?color[c]*cbs:(2 - cbs)*color[c] + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a Gouraud-shaded 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param bs0 Brightness factor of the first vertex (in [0,2]).
       \param bs1 brightness factor of the second vertex (in [0,2]).
       \param bs2 brightness factor of the third vertex (in [0,2]).
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const tc *const color,
                           float bs0,
                           float bs1,
                           float bs2,
                           const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,bs0,bs1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,bs0,bs2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,bs1,bs2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float dbs01 = bs1 - bs0, dbs02 = bs2 - bs0, dbs12 = bs2 - bs1;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          bsm = y<y1?(bs0 + dbs01*yy0/dy01):(bs1 + dbs12*yy1/dy12),
          bsM = bs0 + dbs02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,bsm,bsM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dbsmM = bsM - bsm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float cbs = cimg::cut(bsm + dbsmM*xxm/dxmM,0.f,2.f);
            cimg_forC(*this,c) {
              const Tfloat val = cbs<=1?color[c]*cbs:(2 - cbs)*color[c] + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a Gouraud-shaded 2D triangle, with z-buffering \overload.
    template<typename tz, typename tc>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const tc *const color,
                           float bs0,
                           float bs1,
                           float bs2,
                           float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,bs0,bs1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,bs0,bs2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,bs1,bs2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        dbs01 = bs1 - bs0, dbs02 = bs2 - bs0, dbs12 = bs2 - bs1;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          bsm = y<y1?(bs0 + dbs01*yy0/dy01):(bs1 + dbs12*yy1/dy12),
          bsM = bs0 + dbs02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,izm,izM,bsm,bsM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm, dbsmM = bsM - bsm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              const float cbs = cimg::cut(bsm + dbsmM*xxm/dxmM,0.f,2.f);
              cimg_forC(*this,c) {
                const Tfloat val = cbs<=1?color[c]*cbs:(2 - cbs)*color[c] + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a color-interpolated 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param color0 Pointer to \c spectrum() consecutive values of type \c T, defining the color of the first vertex.
       \param color1 Pointer to \c spectrum() consecutive values of type \c T, defining the color of the second vertex.
       \param color2 Pointer to \c spectrum() consecutive values of type \c T, defining the color of the third vertex.
       \param opacity Drawing opacity.
     **/
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const tc *color0,
                           const tc *color1,
                           const tc *color2,
                           const float opacity=1) {
      typedef typename cimg::superset<tc,int>::type stc;
      if (is_empty()) return *this;
      if (!color0 || !color1 || !color2)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): One of the specified color is (null).",
                                    cimg_instance);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,color0,color1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,color0,color2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,color1,color2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;

      cimg_init_scanline(opacity);

      cimg_forC(*this,c) {
        const stc dcolor01 = color1[c] - color0[c], dcolor02 = color2[c] - color0[c], dcolor12 = color2[c] - color1[c];

        for (int y = cy0; y<=cy2; ++y) {
          const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
          longT
            xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
            xM = x0 + cimg_rd(dx02,yy0,dy02);
          stc
            colorm = y<y1?(color0[c] + dcolor01*yy0/dy01):(color1[c] + dcolor12*yy1/dy12),
            colorM = color0[c] + dcolor02*yy0/dy02;
          if (xm>xM) cimg::swap(xm,xM,colorm,colorM);
          if (xM>=0 && xm<=w1) {
            const int
              cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
              cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
            T *ptrd = data(cxm,y);
            const longT dxmM = std::max((longT)1,xM - xm);
            const stc dcolormM = colorM - colorm;

            for (int x = cxm; x<=cxM; ++x) {
              const longT xxm = (longT)x - xm;
              const stc col = colorm + dcolormM*xxm/dxmM;
              ptrd[c*_sc_whd] = (T)(opacity>=1?col:col*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              ++ptrd;
            }
          }
        }
      }
      return *this;
    }

    //! Draw a textured 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param texture Texture image used to fill the triangle.
       \param tx0 X-coordinate of the first vertex in the texture image.
       \param ty0 Y-coordinate of the first vertex in the texture image.
       \param tx1 X-coordinate of the second vertex in the texture image.
       \param ty1 Y-coordinate of the second vertex in the texture image.
       \param tx2 X-coordinate of the third vertex in the texture image.
       \param ty2 Y-coordinate of the third vertex in the texture image.
       \param opacity Drawing opacity.
       \param brightness Brightness factor of the drawing (in [0,2]).
    **/
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const float opacity=1,
                           const float brightness=1) {
      if (is_empty()) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_triangle(x0,y0,x1,y1,x2,y2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,opacity,brightness);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,tx0,tx1,ty0,ty1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,tx0,tx2,ty0,ty2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,tx1,tx2,ty1,ty2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2,
        dtx01 = (longT)tx1 - tx0, dtx02 = (longT)tx2 - tx0, dtx12 = (longT)tx2 - tx1,
        dty01 = (longT)ty1 - ty0, dty02 = (longT)ty2 - ty0, dty12 = (longT)ty2 - ty1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      const float cbs = cimg::cut(brightness,0.f,2.f);

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02),
          txm = y<y1?tx0 + cimg_rd(dtx01,yy0,dy01):tx1 + cimg_rd(dtx12,yy1,dy12),
          txM = tx0 + cimg_rd(dtx02,yy0,dy02),
          tym = y<y1?ty0 + cimg_rd(dty01,yy0,dy01):ty1 + cimg_rd(dty12,yy1,dy12),
          tyM = ty0 + cimg_rd(dty02,yy0,dy02);
        if (xm>xM) cimg::swap(xm,xM,txm,txM,tym,tyM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT
            dxmM = std::max((longT)1,xM - xm), hdxmM = dxmM/2,
            dtxmM = txM - txm, dtymM = tyM - tym;

          for (int x = cxm; x<=cxM; ++x) {
            const longT
              xxm = (longT)x - xm,
              tx = (txm*dxmM + dtxmM*xxm + hdxmM)/dxmM,
              ty = (tym*dxmM + dtymM*xxm + hdxmM)/dxmM;
            const tc *const color = &texture._atXY(tx,ty);
            cimg_forC(*this,c) {
              const Tfloat val = cbs<=1?color[c*twhd]*cbs:(2 - cbs)*color[c*twhd] + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a 2D textured triangle, with perspective correction.
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const float opacity=1,
                           const float brightness=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,opacity,brightness);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      const float cbs = cimg::cut(brightness,0.f,2.f);

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,txzm,txzM,tyzm,tyzM,izm,izM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm, dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float
              iz = izm + dizmM*xxm/dxmM,
              txz = txzm + dtxzmM*xxm/dxmM,
              tyz = tyzm + dtyzmM*xxm/dxmM;
            const int
              tx = (int)(txz/iz),
              ty = (int)(tyz/iz);
            const tc *const color = &texture._atXY(tx,ty);
            cimg_forC(*this,c) {
              const Tfloat val = cbs<=1?color[c*twhd]*cbs:(2 - cbs)*color[c*twhd] + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a textured 2D triangle, with perspective correction and z-buffering.
    template<typename tz, typename tc>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const float opacity=1,
                           const float brightness=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);

      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,opacity,brightness);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;
      const float cbs = cimg::cut(brightness,0.f,2.f);

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,txzm,txzM,tyzm,tyzM,izm,izM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm, dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              const float
                txz = txzm + dtxzmM*xxm/dxmM,
                tyz = tyzm + dtyzmM*xxm/dxmM;
              const int
                tx = (int)(txz/iz),
                ty = (int)(tyz/iz);
              const tc *const color = &texture._atXY(tx,ty);
              cimg_forC(*this,c) {
                const Tfloat val = cbs<=1?color[c*twhd]*cbs:(2 - cbs)*color[c*twhd] + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a Phong-shaded 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param light Light image.
       \param lx0 X-coordinate of the first vertex in the light image.
       \param ly0 Y-coordinate of the first vertex in the light image.
       \param lx1 X-coordinate of the second vertex in the light image.
       \param ly1 Y-coordinate of the second vertex in the light image.
       \param lx2 X-coordinate of the third vertex in the light image.
       \param ly2 Y-coordinate of the third vertex in the light image.
       \param opacity Drawing opacity.
    **/
    template<typename tc, typename tl>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const tc *const color,
                           const CImg<tl>& light,
                           int lx0, int ly0,
                           int lx1, int ly1,
                           int lx2, int ly2,
                           const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      if (light._depth>1 || light._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified light texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,light._width,light._height,light._depth,light._spectrum,light._data);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,lx0,lx1,ly0,ly1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,lx0,lx2,ly0,ly2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,lx1,lx2,ly1,ly2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2,
        dlx01 = (longT)lx1 - lx0, dlx02 = (longT)lx2 - lx0, dlx12 = (longT)lx2 - lx1,
        dly01 = (longT)ly1 - ly0, dly02 = (longT)ly2 - ly0, dly12 = (longT)ly2 - ly1;
      const ulongT lwhd = (ulongT)light._width*light._height*light._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02),
          lxm = y<y1?lx0 + cimg_rd(dlx01,yy0,dy01):lx1 + cimg_rd(dlx12,yy1,dy12),
          lxM = lx0 + cimg_rd(dlx02,yy0,dy02),
          lym = y<y1?ly0 + cimg_rd(dly01,yy0,dy01):ly1 + cimg_rd(dly12,yy1,dy12),
          lyM = ly0 + cimg_rd(dly02,yy0,dy02);
        if (xm>xM) cimg::swap(xm,xM,lxm,lxM,lym,lyM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT
            dxmM = std::max((longT)1,xM - xm), hdxmM = dxmM/2,
            dlxmM = lxM - lxm, dlymM = lyM - lym;

          for (int x = cxm; x<=cxM; ++x) {
            const longT
              xxm = (longT)x - xm,
              lx = (lxm*dxmM + dlxmM*xxm + hdxmM)/dxmM,
              ly = (lym*dxmM + dlymM*xxm + hdxmM)/dxmM;
            const tl *const lig = &light._atXY(lx,ly);
            cimg_forC(*this,c) {
              const tc col = color[c];
              const float cbs = cimg::cut((float)lig[c*lwhd],0.f,2.f);
              const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a Phong-shaded 2D triangle, with z-buffering.
    template<typename tz, typename tc, typename tl>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const tc *const color,
                           const CImg<tl>& light,
                           int lx0, int ly0,
                           int lx1, int ly1,
                           int lx2, int ly2,
                           const float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Specified color is (null).",
                                    cimg_instance);
      if (light._depth>1 || light._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified light texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,light._width,light._height,light._depth,light._spectrum,light._data);
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);
      if (is_overlapped(light)) return draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,color,
                                                     +light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,lx0,lx1,ly0,ly1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,lx0,lx2,ly0,ly2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,lx1,lx2,ly1,ly2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2,
        dlx01 = (longT)lx1 - lx0, dlx02 = (longT)lx2 - lx0, dlx12 = (longT)lx2 - lx1,
        dly01 = (longT)ly1 - ly0, dly02 = (longT)ly2 - ly0, dly12 = (longT)ly2 - ly1;
      const float diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1;
      const ulongT lwhd = (ulongT)light._width*light._height*light._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02),
          lxm = y<y1?lx0 + cimg_rd(dlx01,yy0,dy01):lx1 + cimg_rd(dlx12,yy1,dy12),
          lxM = lx0 + cimg_rd(dlx02,yy0,dy02),
          lym = y<y1?ly0 + cimg_rd(dly01,yy0,dy01):ly1 + cimg_rd(dly12,yy1,dy12),
          lyM = ly0 + cimg_rd(dly02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02;

        if (xm>xM) cimg::swap(xm,xM,lxm,lxM,lym,lyM,izm,izM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT
            dxmM = std::max((longT)1,xM - xm), hdxmM = dxmM/2,
            dlxmM = lxM - lxm, dlymM = lyM - lym;
          const float dizmM = izM - izm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              const int
                lx = (int)((lxm*dxmM + dlxmM*xxm + hdxmM)/dxmM),
                ly = (int)((lym*dxmM + dlymM*xxm + hdxmM)/dxmM);
              const tl *const lig = &light._atXY(lx,ly);
              cimg_forC(*this,c) {
                const float cbs = cimg::cut((float)lig[c*lwhd],0.f,2.f);
                const tc col = color[c];
                const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Gouraud-shaded 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param texture Texture image used to fill the triangle.
       \param tx0 X-coordinate of the first vertex in the texture image.
       \param ty0 Y-coordinate of the first vertex in the texture image.
       \param tx1 X-coordinate of the second vertex in the texture image.
       \param ty1 Y-coordinate of the second vertex in the texture image.
       \param tx2 X-coordinate of the third vertex in the texture image.
       \param ty2 Y-coordinate of the third vertex in the texture image.
       \param bs0 Brightness factor of the first vertex.
       \param bs1 Brightness factor of the second vertex.
       \param bs2 Brightness factor of the third vertex.
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           float bs0,
                           float bs1,
                           float bs2,
                           const float opacity=1) {
      if (is_empty()) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_triangle(x0,y0,x1,y1,x2,y2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,
                             bs0,bs1,bs2,opacity);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,tx0,tx1,ty0,ty1,bs0,bs1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,tx0,tx2,ty0,ty2,bs0,bs2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,tx1,tx2,ty1,ty2,bs1,bs2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2,
        dtx01 = (longT)tx1 - tx0, dtx02 = (longT)tx2 - tx0, dtx12 = (longT)tx2 - tx1,
        dty01 = (longT)ty1 - ty0, dty02 = (longT)ty2 - ty0, dty12 = (longT)ty2 - ty1;
      const float dbs01 = bs1 - bs0, dbs02 = bs2 - bs0, dbs12 = bs2 - bs1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02),
          txm = y<y1?tx0 + cimg_rd(dtx01,yy0,dy01):tx1 + cimg_rd(dtx12,yy1,dy12),
          txM = tx0 + cimg_rd(dtx02,yy0,dy02),
          tym = y<y1?ty0 + cimg_rd(dty01,yy0,dy01):ty1 + cimg_rd(dty12,yy1,dy12),
          tyM = ty0 + cimg_rd(dty02,yy0,dy02);
        float
          bsm = y<y1?(bs0 + dbs01*yy0/dy01):(bs1 + dbs12*yy1/dy12),
          bsM = bs0 + dbs02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,txm,txM,tym,tyM,bsm,bsM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT
            dxmM = std::max((longT)1,xM - xm), hdxmM = dxmM/2,
            dtxmM = txM - txm, dtymM = tyM - tym;
          const float dbsmM = bsM - bsm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT
              xxm = (longT)x - xm,
              tx = (txm*dxmM + dtxmM*xxm + hdxmM)/dxmM,
              ty = (tym*dxmM + dtymM*xxm + hdxmM)/dxmM;
            const float cbs = cimg::cut(bsm + dbsmM*xxm/dxmM,0.f,2.f);
            const tc *const color = &texture._atXY(tx,ty);
            cimg_forC(*this,c) {
              const tc col = color[c*twhd];
              const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Gouraud-shaded 2D triangle, with perspective correction \overload.
    template<typename tc>
    CImg<T>& draw_triangle(int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           float bs0,
                           float bs1,
                           float bs2,
                           const float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture)) return draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,
                                                       bs0,bs1,bs2,opacity);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1,bs0,bs1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2,bs0,bs2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2,bs1,bs2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1,
        dbs01 = bs1 - bs0, dbs02 = bs2 - bs0, dbs12 = bs2 - bs1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02,
          bsm = y<y1?(bs0 + dbs01*yy0/dy01):(bs1 + dbs12*yy1/dy12),
          bsM = bs0 + dbs02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,txzm,txzM,tyzm,tyzM,izm,izM,bsm,bsM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm, dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm, dbsmM = bsM - bsm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float
              iz = izm + dizmM*xxm/dxmM,
              txz = txzm + dtxzmM*xxm/dxmM,
              tyz = tyzm + dtyzmM*xxm/dxmM,
              cbs = cimg::cut(bsm + dbsmM*xxm/dxmM,0.f,2.f);
            const int
              tx = (int)(txz/iz),
              ty = (int)(tyz/iz);
            const tc *const color = &texture._atXY(tx,ty);
            cimg_forC(*this,c) {
              const tc col = color[c*twhd];
              const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Gouraud-shaded 2D triangle, with perspective correction and z-buffering \overload.
    template<typename tz, typename tc>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           float bs0,
                           float bs1,
                           float bs2,
                           const float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (is_overlapped(texture))
        return draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,bs0,bs1,bs2,opacity);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1,bs0,bs1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2,bs0,bs2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2,bs1,bs2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1,
        dbs01 = bs1 - bs0, dbs02 = bs2 - bs0, dbs12 = bs2 - bs1;
      const ulongT twhd = (ulongT)texture._width*texture._height*texture._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02,
          bsm = y<y1?(bs0 + dbs01*yy0/dy01):(bs1 + dbs12*yy1/dy12),
          bsM = bs0 + dbs02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,txzm,txzM,tyzm,tyzM,izm,izM,bsm,bsM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float dizmM = izM - izm, dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm, dbsmM = bsM - bsm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              const float
                txz = txzm + dtxzmM*xxm/dxmM,
                tyz = tyzm + dtyzmM*xxm/dxmM,
                cbs = cimg::cut(bsm + dbsmM*xxm/dxmM,0.f,2.f);
              const int
                tx = (int)(txz/iz),
                ty = (int)(tyz/iz);
              const tc *const color = &texture._atXY(tx,ty);
              cimg_forC(*this,c) {
                const tc col = color[c*twhd];
                const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Phong-shaded 2D triangle.
    /**
       \param x0 X-coordinate of the first vertex in the image instance.
       \param y0 Y-coordinate of the first vertex in the image instance.
       \param x1 X-coordinate of the second vertex in the image instance.
       \param y1 Y-coordinate of the second vertex in the image instance.
       \param x2 X-coordinate of the third vertex in the image instance.
       \param y2 Y-coordinate of the third vertex in the image instance.
       \param texture Texture image used to fill the triangle.
       \param tx0 X-coordinate of the first vertex in the texture image.
       \param ty0 Y-coordinate of the first vertex in the texture image.
       \param tx1 X-coordinate of the second vertex in the texture image.
       \param ty1 Y-coordinate of the second vertex in the texture image.
       \param tx2 X-coordinate of the third vertex in the texture image.
       \param ty2 Y-coordinate of the third vertex in the texture image.
       \param light Light image.
       \param lx0 X-coordinate of the first vertex in the light image.
       \param ly0 Y-coordinate of the first vertex in the light image.
       \param lx1 X-coordinate of the second vertex in the light image.
       \param ly1 Y-coordinate of the second vertex in the light image.
       \param lx2 X-coordinate of the third vertex in the light image.
       \param ly2 Y-coordinate of the third vertex in the light image.
       \param opacity Drawing opacity.
    **/
    template<typename tc, typename tl>
    CImg<T>& draw_triangle(int x0, int y0,
                           int x1, int y1,
                           int x2, int y2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const CImg<tl>& light,
                           int lx0, int ly0,
                           int lx1, int ly1,
                           int lx2, int ly2,
                           const float opacity=1) {
      if (is_empty()) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (light._depth>1 || light._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified light texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,light._width,light._height,light._depth,light._spectrum,light._data);
      if (is_overlapped(texture))
        return draw_triangle(x0,y0,x1,y1,x2,y2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      if (is_overlapped(light))
        return draw_triangle(x0,y0,x1,y1,x2,y2,texture,tx0,ty0,tx1,ty1,tx2,ty2,+light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);

      if (y0>y1) cimg::swap(x0,x1,y0,y1,tx0,tx1,ty0,ty1,lx0,lx1,ly0,ly1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,tx0,tx2,ty0,ty2,lx0,lx2,ly0,ly2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,tx1,tx2,ty1,ty2,lx1,lx2,ly1,ly2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2,
        dtx01 = (longT)tx1 - tx0, dtx02 = (longT)tx2 - tx0, dtx12 = (longT)tx2 - tx1,
        dty01 = (longT)ty1 - ty0, dty02 = (longT)ty2 - ty0, dty12 = (longT)ty2 - ty1,
        dlx01 = (longT)lx1 - lx0, dlx02 = (longT)lx2 - lx0, dlx12 = (longT)lx2 - lx1,
        dly01 = (longT)ly1 - ly0, dly02 = (longT)ly2 - ly0, dly12 = (longT)ly2 - ly1;
      const ulongT
        twhd = (ulongT)texture._width*texture._height*texture._depth,
        lwhd = (ulongT)light._width*light._height*light._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02),
          txm = y<y1?tx0 + cimg_rd(dtx01,yy0,dy01):tx1 + cimg_rd(dtx12,yy1,dy12),
          txM = tx0 + cimg_rd(dtx02,yy0,dy02),
          tym = y<y1?ty0 + cimg_rd(dty01,yy0,dy01):ty1 + cimg_rd(dty12,yy1,dy12),
          tyM = ty0 + cimg_rd(dty02,yy0,dy02),
          lxm = y<y1?lx0 + cimg_rd(dlx01,yy0,dy01):lx1 + cimg_rd(dlx12,yy1,dy12),
          lxM = lx0 + cimg_rd(dlx02,yy0,dy02),
          lym = y<y1?ly0 + cimg_rd(dly01,yy0,dy01):ly1 + cimg_rd(dly12,yy1,dy12),
          lyM = ly0 + cimg_rd(dly02,yy0,dy02);
        if (xm>xM) cimg::swap(xm,xM,txm,txM,tym,tyM,lxm,lxM,lym,lyM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT
            dxmM = std::max((longT)1,xM - xm), hdxmM = dxmM/2,
            dtxmM = txM - txm, dtymM = tyM - tym,
            dlxmM = lxM - lxm, dlymM = lyM - lym;

          for (int x = cxm; x<=cxM; ++x) {
            const longT
              xxm = (longT)x - xm,
              tx = (txm*dxmM + dtxmM*xxm + hdxmM)/dxmM,
              ty = (tym*dxmM + dtymM*xxm + hdxmM)/dxmM,
              lx = (lxm*dxmM + dlxmM*xxm + hdxmM)/dxmM,
              ly = (lym*dxmM + dlymM*xxm + hdxmM)/dxmM;
            const tc *const color = &texture._atXY(tx,ty);
            const tl *const lig = &light._atXY(lx,ly);
            cimg_forC(*this,c) {
              const tc col = color[c*twhd];
              const float cbs = cimg::cut((float)lig[c*lwhd],0.f,2.f);
              const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Phong-shaded 2D triangle, with perspective correction.
    template<typename tc, typename tl>
    CImg<T>& draw_triangle(int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const CImg<tl>& light,
                           int lx0, int ly0,
                           int lx1, int ly1,
                           int lx2, int ly2,
                           const float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (light._depth>1 || light._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified light texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,light._width,light._height,light._depth,light._spectrum,light._data);
      if (is_overlapped(texture))
        return draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,+texture,tx0,ty0,tx1,ty1,tx2,ty2,
                             light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      if (is_overlapped(light))
        return draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,texture,tx0,ty0,tx1,ty1,tx2,ty2,
                             +light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1,lx0,lx1,ly0,ly1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2,lx0,lx2,ly0,ly2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2,lx1,lx2,ly1,ly2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1,
        lxz0 = lx0*iz0, lxz1 = lx1*iz1, lxz2 = lx2*iz2,
        lyz0 = ly0*iz0, lyz1 = ly1*iz1, lyz2 = ly2*iz2,
        dlxz01 = lxz1 - lxz0, dlxz02 = lxz2 - lxz0, dlxz12 = lxz2 - lxz1,
        dlyz01 = lyz1 - lyz0, dlyz02 = lyz2 - lyz0, dlyz12 = lyz2 - lyz1;
      const ulongT
        twhd = (ulongT)texture._width*texture._height*texture._depth,
        lwhd = (ulongT)light._width*light._height*light._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02,
          lxzm = y<y1?(lxz0 + dlxz01*yy0/dy01):(lxz1 + dlxz12*yy1/dy12),
          lxzM = lxz0 + dlxz02*yy0/dy02,
          lyzm = y<y1?(lyz0 + dlyz01*yy0/dy01):(lyz1 + dlyz12*yy1/dy12),
          lyzM = lyz0 + dlyz02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,izm,izM,txzm,txzM,tyzm,tyzM,lxzm,lxzM,lyzm,lyzM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float
            dizmM = izM - izm,
            dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm,
            dlxzmM = lxzM - lxzm, dlyzmM = lyzM - lyzm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float
              iz = izm + dizmM*xxm/dxmM,
              txz = txzm + dtxzmM*xxm/dxmM,
              tyz = tyzm + dtyzmM*xxm/dxmM,
              lxz = lxzm + dlxzmM*xxm/dxmM,
              lyz = lyzm + dlyzmM*xxm/dxmM;
            const int
              tx = (int)(txz/iz),
              ty = (int)(tyz/iz),
              lx = (int)(lxz/iz),
              ly = (int)(lyz/iz);
            const tc *const color = &texture._atXY(tx,ty);
            const tl *const lig = &light._atXY(lx,ly);
            cimg_forC(*this,c) {
              const tc col = color[c*twhd];
              const float cbs = cimg::cut((float)lig[c*lwhd],0.f,2.f);
              const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
              ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
            }
            ++ptrd;
          }
        }
      }
      return *this;
    }

    //! Draw a textured Phong-shaded 2D triangle, with perspective correction and z-buffering.
    template<typename tz, typename tc, typename tl>
    CImg<T>& draw_triangle(CImg<tz>& zbuffer,
                           int x0, int y0, const float z0,
                           int x1, int y1, const float z1,
                           int x2, int y2, const float z2,
                           const CImg<tc>& texture,
                           int tx0, int ty0,
                           int tx1, int ty1,
                           int tx2, int ty2,
                           const CImg<tl>& light,
                           int lx0, int ly0,
                           int lx1, int ly1,
                           int lx2, int ly2,
                           const float opacity=1) {
      if (is_empty() || z0<=0 || z1<=0 || z2<=0) return *this;
      if (!is_sameXY(zbuffer))
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Instance and specified Z-buffer (%u,%u,%u,%u,%p) have "
                                    "different dimensions.",
                                    cimg_instance,
                                    zbuffer._width,zbuffer._height,zbuffer._depth,zbuffer._spectrum,zbuffer._data);
      if (texture._depth>1 || texture._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    texture._width,texture._height,texture._depth,texture._spectrum,texture._data);
      if (light._depth>1 || light._spectrum<_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_triangle(): Invalid specified light texture (%u,%u,%u,%u,%p).",
                                    cimg_instance,light._width,light._height,light._depth,light._spectrum,light._data);
      if (is_overlapped(texture))
        return draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,
                             +texture,tx0,ty0,tx1,ty1,tx2,ty2,light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      if (is_overlapped(light))
        return draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,
                             texture,tx0,ty0,tx1,ty1,tx2,ty2,+light,lx0,ly0,lx1,ly1,lx2,ly2,opacity);

      float iz0 = 1/z0, iz1 = 1/z1, iz2 = 1/z2;
      if (y0>y1) cimg::swap(x0,x1,y0,y1,iz0,iz1,tx0,tx1,ty0,ty1,lx0,lx1,ly0,ly1);
      if (y0>y2) cimg::swap(x0,x2,y0,y2,iz0,iz2,tx0,tx2,ty0,ty2,lx0,lx2,ly0,ly2);
      if (y1>y2) cimg::swap(x1,x2,y1,y2,iz1,iz2,tx1,tx2,ty1,ty2,lx1,lx2,ly1,ly2);
      if (y2<0 || y0>=height() || cimg::min(x0,x1,x2)>=width() || cimg::max(x0,x1,x2)<0 || !opacity) return *this;

      const int w1 = width() - 1, h1 = height() - 1, cy0 = cimg::cut(y0,0,h1), cy2 = cimg::cut(y2,0,h1);
      const longT
        dx01 = (longT)x1 - x0, dx02 = (longT)x2 - x0, dx12 = (longT)x2 - x1,
        dy01 = std::max((longT)1,(longT)y1 - y0),
        dy02 = std::max((longT)1,(longT)y2 - y0),
        dy12 = std::max((longT)1,(longT)y2 - y1),
        hdy01 = dy01/2, hdy02 = dy02/2, hdy12 = dy12/2;
      const float
        diz01 = iz1 - iz0, diz02 = iz2 - iz0, diz12 = iz2 - iz1,
        txz0 = tx0*iz0, txz1 = tx1*iz1, txz2 = tx2*iz2,
        tyz0 = ty0*iz0, tyz1 = ty1*iz1, tyz2 = ty2*iz2,
        dtxz01 = txz1 - txz0, dtxz02 = txz2 - txz0, dtxz12 = txz2 - txz1,
        dtyz01 = tyz1 - tyz0, dtyz02 = tyz2 - tyz0, dtyz12 = tyz2 - tyz1,
        lxz0 = lx0*iz0, lxz1 = lx1*iz1, lxz2 = lx2*iz2,
        lyz0 = ly0*iz0, lyz1 = ly1*iz1, lyz2 = ly2*iz2,
        dlxz01 = lxz1 - lxz0, dlxz02 = lxz2 - lxz0, dlxz12 = lxz2 - lxz1,
        dlyz01 = lyz1 - lyz0, dlyz02 = lyz2 - lyz0, dlyz12 = lyz2 - lyz1;
      const ulongT
        twhd = (ulongT)texture._width*texture._height*texture._depth,
        lwhd = (ulongT)light._width*light._height*light._depth;

      cimg_init_scanline(opacity);

      for (int y = cy0; y<=cy2; ++y) {
        const longT yy0 = (longT)y - y0, yy1 = (longT)y - y1;
        longT
          xm = y<y1?x0 + cimg_rd(dx01,yy0,dy01):x1 + cimg_rd(dx12,yy1,dy12),
          xM = x0 + cimg_rd(dx02,yy0,dy02);
        float
          izm = y<y1?(iz0 + diz01*yy0/dy01):(iz1 + diz12*yy1/dy12),
          izM = iz0 + diz02*yy0/dy02,
          txzm = y<y1?(txz0 + dtxz01*yy0/dy01):(txz1 + dtxz12*yy1/dy12),
          txzM = txz0 + dtxz02*yy0/dy02,
          tyzm = y<y1?(tyz0 + dtyz01*yy0/dy01):(tyz1 + dtyz12*yy1/dy12),
          tyzM = tyz0 + dtyz02*yy0/dy02,
          lxzm = y<y1?(lxz0 + dlxz01*yy0/dy01):(lxz1 + dlxz12*yy1/dy12),
          lxzM = lxz0 + dlxz02*yy0/dy02,
          lyzm = y<y1?(lyz0 + dlyz01*yy0/dy01):(lyz1 + dlyz12*yy1/dy12),
          lyzM = lyz0 + dlyz02*yy0/dy02;
        if (xm>xM) cimg::swap(xm,xM,izm,izM,txzm,txzM,tyzm,tyzM,lxzm,lxzM,lyzm,lyzM);
        if (xM>=0 && xm<=w1) {
          const int
            cxm = (int)cimg::cut(xm,(longT)0,(longT)w1),
            cxM = (int)cimg::cut(xM,(longT)0,(longT)w1);
          T *ptrd = data(cxm,y);
          tz *ptrz = zbuffer.data(cxm,y);
          const longT dxmM = std::max((longT)1,xM - xm);
          const float
            dizmM = izM - izm,
            dtxzmM = txzM - txzm, dtyzmM = tyzM - tyzm,
            dlxzmM = lxzM - lxzm, dlyzmM = lyzM - lyzm;

          for (int x = cxm; x<=cxM; ++x) {
            const longT xxm = (longT)x - xm;
            const float iz = izm + dizmM*xxm/dxmM;
            if (iz>=*ptrz) {
              *ptrz = (tz)iz;
              const float
                txz = txzm + dtxzmM*xxm/dxmM,
                tyz = tyzm + dtyzmM*xxm/dxmM,
                lxz = lxzm + dlxzmM*xxm/dxmM,
                lyz = lyzm + dlyzmM*xxm/dxmM;
              const int
                tx = (int)(txz/iz),
                ty = (int)(tyz/iz),
                lx = (int)(lxz/iz),
                ly = (int)(lyz/iz);
              const tc *const color = &texture._atXY(tx,ty);
              const tl *const lig = &light._atXY(lx,ly);
              cimg_forC(*this,c) {
                const tc col = color[c*twhd];
                const float cbs = cimg::cut((float)lig[c*lwhd],0.f,2.f);
                const Tfloat val = cbs<=1?cbs*col:(2 - cbs)*col + (cbs - 1)*_sc_maxval;
                ptrd[c*_sc_whd] = (T)(opacity>=1?val:val*_sc_nopacity + ptrd[c*_sc_whd]*_sc_copacity);
              }
            }
            ++ptrd; ++ptrz;
          }
        }
      }
      return *this;
    }

    //! Draw a filled 4D rectangle.
    /**
       \param x0 X-coordinate of the upper-left rectangle corner.
       \param y0 Y-coordinate of the upper-left rectangle corner.
       \param z0 Z-coordinate of the upper-left rectangle corner.
       \param c0 C-coordinate of the upper-left rectangle corner.
       \param x1 X-coordinate of the lower-right rectangle corner.
       \param y1 Y-coordinate of the lower-right rectangle corner.
       \param z1 Z-coordinate of the lower-right rectangle corner.
       \param c1 C-coordinate of the lower-right rectangle corner.
       \param val Scalar value used to fill the rectangle area.
       \param opacity Drawing opacity.
    **/
    CImg<T>& draw_rectangle(const int x0, const int y0, const int z0, const int c0,
                            const int x1, const int y1, const int z1, const int c1,
                            const T val, const float opacity=1) {
      if (is_empty()) return *this;
      const int
        nx0 = x0<x1?x0:x1, nx1 = x0^x1^nx0,
        ny0 = y0<y1?y0:y1, ny1 = y0^y1^ny0,
        nz0 = z0<z1?z0:z1, nz1 = z0^z1^nz0,
        nc0 = c0<c1?c0:c1, nc1 = c0^c1^nc0;
      const int
        lx = (1 + nx1 - nx0) + (nx1>=width()?width() - 1 - nx1:0) + (nx0<0?nx0:0),
        ly = (1 + ny1 - ny0) + (ny1>=height()?height() - 1 - ny1:0) + (ny0<0?ny0:0),
        lz = (1 + nz1 - nz0) + (nz1>=depth()?depth() - 1 - nz1:0) + (nz0<0?nz0:0),
        lc = (1 + nc1 - nc0) + (nc1>=spectrum()?spectrum() - 1 - nc1:0) + (nc0<0?nc0:0);
      const ulongT
        offX = (ulongT)_width - lx,
        offY = (ulongT)_width*(_height - ly),
        offZ = (ulongT)_width*_height*(_depth - lz);
      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      T *ptrd = data(nx0<0?0:nx0,ny0<0?0:ny0,nz0<0?0:nz0,nc0<0?0:nc0);
      if (lx>0 && ly>0 && lz>0 && lc>0)
        for (int v = 0; v<lc; ++v) {
          for (int z = 0; z<lz; ++z) {
            for (int y = 0; y<ly; ++y) {
              if (opacity>=1) {
                if (sizeof(T)!=1) { for (int x = 0; x<lx; ++x) *(ptrd++) = val; ptrd+=offX; }
                else { std::memset(ptrd,(int)val,lx); ptrd+=_width; }
              } else { for (int x = 0; x<lx; ++x) { *ptrd = (T)(nopacity*val + *ptrd*copacity); ++ptrd; } ptrd+=offX; }
            }
            ptrd+=offY;
          }
          ptrd+=offZ;
        }
      return *this;
    }

    //! Draw a filled 3D rectangle.
    /**
       \param x0 X-coordinate of the upper-left rectangle corner.
       \param y0 Y-coordinate of the upper-left rectangle corner.
       \param z0 Z-coordinate of the upper-left rectangle corner.
       \param x1 X-coordinate of the lower-right rectangle corner.
       \param y1 Y-coordinate of the lower-right rectangle corner.
       \param z1 Z-coordinate of the lower-right rectangle corner.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_rectangle(const int x0, const int y0, const int z0,
                            const int x1, const int y1, const int z1,
                            const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_rectangle(): Specified color is (null).",
                                    cimg_instance);
      cimg_forC(*this,c) draw_rectangle(x0,y0,z0,c,x1,y1,z1,c,(T)color[c],opacity);
      return *this;
    }

    //! Draw a filled 2D rectangle.
    /**
       \param x0 X-coordinate of the upper-left rectangle corner.
       \param y0 Y-coordinate of the upper-left rectangle corner.
       \param x1 X-coordinate of the lower-right rectangle corner.
       \param y1 Y-coordinate of the lower-right rectangle corner.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_rectangle(const int x0, const int y0,
                            const int x1, const int y1,
                            const tc *const color, const float opacity=1) {
      return draw_rectangle(x0,y0,0,x1,y1,_depth - 1,color,opacity);
    }

    //! Draw a outlined 2D rectangle \overload.
    template<typename tc>
    CImg<T>& draw_rectangle(const int x0, const int y0,
                            const int x1, const int y1,
                            const tc *const color, const float opacity,
                            const unsigned int pattern) {
      if (is_empty()) return *this;
      if (y0==y1) return draw_line(x0,y0,x1,y0,color,opacity,pattern,true);
      if (x0==x1) return draw_line(x0,y0,x0,y1,color,opacity,pattern,true);
      const int
        nx0 = x0<x1?x0:x1, nx1 = x0^x1^nx0,
        ny0 = y0<y1?y0:y1, ny1 = y0^y1^ny0;
      if (ny1==ny0 + 1) return draw_line(nx0,ny0,nx1,ny0,color,opacity,pattern,true).
                      draw_line(nx1,ny1,nx0,ny1,color,opacity,pattern,false);
      return draw_line(nx0,ny0,nx1,ny0,color,opacity,pattern,true).
        draw_line(nx1,ny0 + 1,nx1,ny1 - 1,color,opacity,pattern,false).
        draw_line(nx1,ny1,nx0,ny1,color,opacity,pattern,false).
        draw_line(nx0,ny1 - 1,nx0,ny0 + 1,color,opacity,pattern,false);
    }

    //! Draw a filled 2D polygon.
    /**
       \param points Set of polygon vertices.
       \param color Pointer to \c spectrum() consecutive values of type \c T, defining the drawing color.
       \param opacity Drawing opacity.
     **/
    template<typename tp, typename tc>
    CImg<T>& draw_polygon(const CImg<tp>& points,
                          const tc *const color, const float opacity=1) {
      if (is_empty() || !points) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_polygon(): Specified color is (null).",
                                    cimg_instance);
      if (points.height()!=2)
        throw CImgArgumentException(_cimg_instance
                                    "draw_polygon(): Invalid specified point set (%u,%u,%u,%u).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum);
      CImg<intT> ipoints;
      if (cimg::type<tp>::is_float()) ipoints = points.get_round();
      else ipoints.assign(points,cimg::type<tp>::string()==cimg::type<int>::string());

      if (ipoints._width==1) return draw_point(ipoints(0,0),ipoints(0,1),color,opacity);
      if (ipoints._width==2) return draw_line(ipoints(0,0),ipoints(0,1),ipoints(1,0),ipoints(1,1),color,opacity);
      if (ipoints._width==3) return draw_triangle(ipoints(0,0),ipoints(0,1),ipoints(1,0),ipoints(1,1),
                                                  ipoints(2,0),ipoints(2,1),color,opacity);
      cimg_init_scanline(opacity);
      int
        xmin = 0, ymin = 0,
        xmax = ipoints.get_shared_row(0).max_min(xmin),
        ymax = ipoints.get_shared_row(1).max_min(ymin);
      if (xmax<0 || xmin>=width() || ymax<0 || ymin>=height()) return *this;
      if (ymin==ymax) return draw_line(xmin,ymin,xmax,ymax,color,opacity);
      ymin = std::max(0,ymin);
      ymax = std::min(height() - 1,ymax);

      CImg<intT> Xs(ipoints._width,ymax - ymin + 1);
      CImg<uintT> count(Xs._height,1,1,1,0);
      unsigned int n = 0, nn = 1;
      bool go_on = true;

      while (go_on) {
        unsigned int an = (nn + 1)%ipoints._width;
        const int x0 = ipoints(n,0), y0 = ipoints(n,1);
        if (ipoints(nn,1)==y0) while (ipoints(an,1)==y0) { nn = an; (an+=1)%=ipoints._width; }
        const int x1 = ipoints(nn,0), y1 = ipoints(nn,1);
        unsigned int tn = an;
        while (ipoints(tn,1)==y1) (tn+=1)%=ipoints._width;
        if (y0!=y1) {
          const int
            y2 = ipoints(tn,1),
            x01 = x1 - x0, y01 = y1 - y0, y12 = y2 - y1,
            step = cimg::sign(y01),
            tmax = std::max(1,cimg::abs(y01)),
            htmax = tmax*cimg::sign(x01)/2 + 1,
            tend = tmax - (step==cimg::sign(y12));
          unsigned int y = (unsigned int)y0 - ymin;
          for (int t = 0; t<=tend; ++t, y+=step)
            if (y<Xs._height) Xs(count[y]++,y) = x0 + cimg_rd(t,x01,tmax);
        }
        go_on = nn>n;
        n = nn;
        nn = an;
      }

      cimg_pragma_openmp(parallel for cimg_openmp_if(Xs._height>=(cimg_openmp_sizefactor)*512))
      cimg_forY(Xs,y) if (count[y]) {
        CImg<intT> Xsy = Xs.get_shared_points(0,count[y] - 1,y);
        Xsy.sort();
        int px = width();
        for (unsigned int k = 0; k + 1<Xsy._width; k+=2) {
          int x0 = Xsy[k];
          const int x1 = Xsy[k + 1];
          x0+=x0==px;
          cimg_draw_scanline(x0,x1,y + ymin,color,opacity,1);
          px = x1;
        }
      }
      return *this;
    }

    //! Draw a outlined 2D or 3D polygon \overload.
    template<typename tp, typename tc>
    CImg<T>& draw_polygon(const CImg<tp>& points,
                          const tc *const color, const float opacity, const unsigned int pattern,
                          const bool is_closed=true) {
      if (is_empty() || !points) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_polygon(): Specified color is (null).",
                                    cimg_instance);
      if (points.height()!=2)
        throw CImgArgumentException(_cimg_instance
                                    "draw_polygon(): Invalid specified point set (%u,%u,%u,%u).",
                                    cimg_instance,
                                    points._width,points._height,points._depth,points._spectrum);
      CImg<intT> ipoints;
      if (cimg::type<tp>::is_float()) ipoints = points.get_round();
      else ipoints.assign(points,cimg::type<tp>::string()==cimg::type<int>::string());

      if (ipoints._width==1) return draw_point(ipoints(0,0),ipoints(0,1),color,opacity);
      if (ipoints._width==2) return draw_line(ipoints(0,0),ipoints(0,1),ipoints(1,0),ipoints(1,1),
                                              color,opacity,pattern);
      bool ninit_hatch = true, is_drawn = false;
      int x0 = ipoints(0,0), y0 = ipoints(0,1);
      const unsigned int N = ipoints._width - (is_closed?0:1);
      for (unsigned int i = 0; i<N; ++i) {
        const int
          ni = (i + 1)%ipoints.width(),
          x1 = ipoints(ni,0), y1 = ipoints(ni,1),
          x01 = x1 - x0, y01 = y1 - y0,
          l = std::max(cimg::abs(x01),cimg::abs(y01));
        if (l) {
          const bool draw_last_pixel = is_closed || i<N - 1?false:true;
          draw_line(x0,y0,x1,y1,color,opacity,pattern,ninit_hatch,draw_last_pixel);
          is_drawn = true;
        }
        ninit_hatch = false;
        x0 = x1; y0 = y1;
      }
      if (!is_drawn) draw_point(ipoints(0,0),ipoints(0,1),color,opacity); // All vertices were the same
      return *this;
    }

    //! Draw a filled 2D ellipse.
    /**
       \param x0 X-coordinate of the ellipse center.
       \param y0 Y-coordinate of the ellipse center.
       \param r1 First radius of the ellipse.
       \param r2 Second radius of the ellipse.
       \param angle Angle of the first radius.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_ellipse(const int x0, const int y0, const float r1, const float r2, const float angle,
                          const tc *const color, const float opacity=1) {
      return _draw_ellipse(x0,y0,r1,r2,angle,color,opacity,0U,true);
    }

    //! Draw a filled 2D ellipse \overload.
    /**
       \param x0 X-coordinate of the ellipse center.
       \param y0 Y-coordinate of the ellipse center.
       \param tensor Diffusion tensor describing the ellipse.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename t, typename tc>
    CImg<T>& draw_ellipse(const int x0, const int y0, const CImg<t> &tensor,
                          const tc *const color, const float opacity=1) {
      CImgList<t> eig = tensor.get_symmetric_eigen();
      const CImg<t> &val = eig[0], &vec = eig[1];
      return draw_ellipse(x0,y0,std::sqrt(val(0)),std::sqrt(val(1)),
                          std::atan2(vec(0,1),vec(0,0))*180/cimg::PI,
                          color,opacity);
    }

    //! Draw an outlined 2D ellipse.
    /**
       \param x0 X-coordinate of the ellipse center.
       \param y0 Y-coordinate of the ellipse center.
       \param r1 First radius of the ellipse.
       \param r2 Second radius of the ellipse.
       \param angle Angle of the first radius.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the outline stipple pattern.
    **/
    template<typename tc>
    CImg<T>& draw_ellipse(const int x0, const int y0, const float r1, const float r2, const float angle,
                          const tc *const color, const float opacity, const unsigned int pattern) {
      if (pattern) _draw_ellipse(x0,y0,r1,r2,angle,color,opacity,pattern,false);
      return *this;
    }

    //! Draw an outlined 2D ellipse \overload.
    /**
       \param x0 X-coordinate of the ellipse center.
       \param y0 Y-coordinate of the ellipse center.
       \param tensor Diffusion tensor describing the ellipse.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the outline stipple pattern.
    **/
    template<typename t, typename tc>
    CImg<T>& draw_ellipse(const int x0, const int y0, const CImg<t> &tensor,
                          const tc *const color, const float opacity,
                          const unsigned int pattern) {
      CImgList<t> eig = tensor.get_symmetric_eigen();
      const CImg<t> &val = eig[0], &vec = eig[1];
      return draw_ellipse(x0,y0,std::sqrt(val(0)),std::sqrt(val(1)),
                          std::atan2(vec(0,1),vec(0,0))*180/cimg::PI,
                          color,opacity,pattern);
    }

    template<typename tc>
    CImg<T>& _draw_ellipse(const int x0, const int y0, const float radius1, const float radius2, const float angle,
                           const tc *const color, const float opacity,
                           const unsigned int pattern, const bool is_filled) {
      if (is_empty() || (!is_filled && !pattern)) return *this;
      const float radiusM = std::max(radius1,radius2);
      if (radius1<0 || radius2<0 || x0 - radiusM>=width() || y0 + radiusM<0 || y0 - radiusM>=height()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_ellipse(): Specified color is (null).",
                                    cimg_instance);
      const int iradius1 = (int)cimg::round(radius1), iradius2 = (int)cimg::round(radius2);
      if (!iradius1 && !iradius2) return draw_point(x0,y0,color,opacity);
      if (iradius1==iradius2) {
        if (is_filled) return draw_circle(x0,y0,iradius1,color,opacity);
        else if (pattern==~0U) return draw_circle(x0,y0,iradius1,color,opacity,pattern);
      }
      const float
        ang = (float)(angle*cimg::PI/180),
        ca = std::cos(ang), sa = std::sin(ang);
      if (!iradius1) {
        const float u = -radius2*sa, v = radius2*ca;
        return draw_line(cimg::round(x0 - u),cimg::round(y0 - v),cimg::round(x0 + u),cimg::round(y0 + v),
                         color,opacity,is_filled?~0U:pattern);
      }
      if (!iradius2) {
        const float u = radius1*ca, v = radius1*sa;
        return draw_line(cimg::round(x0 - u),cimg::round(y0 - v),cimg::round(x0 + u),cimg::round(y0 + v),
                         color,opacity,is_filled?~0U:pattern);
      }

      if (!is_filled) { // Outlined
        CImg<int> points((unsigned int)cimg::round(6*radiusM),2);
        cimg_forX(points,k) {
          const float
            _ang = (float)(2*cimg::PI*k/points._width),
            X = (float)(radius1*std::cos(_ang)),
            Y = (float)(radius2*std::sin(_ang));
          points(k,0) = (int)cimg::round(x0 + (X*ca - Y*sa));
          points(k,1) = (int)cimg::round(y0 + (X*sa + Y*ca));
        }
        draw_polygon(points,color,opacity,pattern);
      } else { // Filled
        cimg_init_scanline(opacity);
        const float
          ca2 = ca*ca,
          sa2 = sa*sa,
          casa = -ca*sa,
          i1 = 1/cimg::sqr(radius1),
          i2 = 1/cimg::sqr(radius2),
          t1 = i1*ca2 + i2*sa2,
          t2 = (i2 - i1)*casa,
          t3 = i2*ca2 + i1*sa2,
          t12 = t1*2;
        const int
          _ymin = (int)std::floor(y0 - radiusM),
          _ymax = (int)std::ceil(y0 + radiusM),
          ymin = _ymin<0?0:_ymin,
          ymax = _ymax>=height()?height() - 1:_ymax;
        for (int y = ymin; y<=ymax; ++y) {
          const float
            Y = y - y0 + 0.5f,
            B = 2*t2*Y,
            C = t3*Y*Y - 1,
            D = B*B - 4*t1*C;
          if (D>=0) {
            const float sD = std::sqrt(D);
            const int
              xmin = (int)(x0 + cimg::round((-B - sD)/t12)),
              xmax = (int)(x0 + cimg::round((-B + sD)/t12));
            cimg_draw_scanline(xmin,xmax,y,color,opacity,1);
          }
        }
      }
      return *this;
    }

    //! Draw a filled 2D circle.
    /**
       \param x0 X-coordinate of the circle center.
       \param y0 Y-coordinate of the circle center.
       \param radius  Circle radius.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \note
       - Circle version of the Bresenham's algorithm is used.
    **/
    template<typename tc>
    CImg<T>& draw_circle(const int x0, const int y0, int radius,
                         const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (radius<0 || x0 + radius<0 || x0 - radius>=width() || y0 + radius<0 || y0 - radius>=height()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_circle(): Specified color is (null).",
                                    cimg_instance);
      if (!radius) return draw_point(x0,y0,color,opacity);
      cimg_init_scanline(opacity);
      if (y0>=0 && y0<height()) cimg_draw_scanline(x0 - radius,x0 + radius,y0,color,opacity,1);
      for (int f = 1 - radius, ddFx = 0, ddFy = -(radius<<1), x = 0, y = radius; x<y; ) {
        if (f>=0) {
          const int x1 = x0 - x, x2 = x0 + x, y1 = y0 - y, y2 = y0 + y;
          if (y1>=0 && y1<height()) cimg_draw_scanline(x1,x2,y1,color,opacity,1);
          if (y2>=0 && y2<height()) cimg_draw_scanline(x1,x2,y2,color,opacity,1);
          f+=(ddFy+=2); --y;
        }
        const bool no_diag = y!=(x++);
        ++(f+=(ddFx+=2));
        const int x1 = x0 - y, x2 = x0 + y, y1 = y0 - x, y2 = y0 + x;
        if (no_diag) {
          if (y1>=0 && y1<height()) cimg_draw_scanline(x1,x2,y1,color,opacity,1);
          if (y2>=0 && y2<height()) cimg_draw_scanline(x1,x2,y2,color,opacity,1);
        }
      }
      return *this;
    }

    //! Draw an outlined 2D circle.
    /**
       \param x0 X-coordinate of the circle center.
       \param y0 Y-coordinate of the circle center.
       \param radius Circle radius.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern An integer whose bits describe the outline stipple pattern.
    **/
    template<typename tc>
    CImg<T>& draw_circle(const int x0, const int y0, int radius,
                         const tc *const color, const float opacity,
                         const unsigned int pattern) {
      if (pattern!=~0U) return draw_ellipse(x0,y0,radius,radius,0,color,opacity,pattern);
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_circle(): Specified color is (null).",
                                    cimg_instance);
      if (radius<0 || x0 - radius>=width() || y0 + radius<0 || y0 - radius>=height()) return *this;
      if (!radius) return draw_point(x0,y0,color,opacity);

      draw_point(x0 - radius,y0,color,opacity).draw_point(x0 + radius,y0,color,opacity).
        draw_point(x0,y0 - radius,color,opacity).draw_point(x0,y0 + radius,color,opacity);
      if (radius==1) return *this;
      for (int f = 1 - radius, ddFx = 0, ddFy = -(radius<<1), x = 0, y = radius; x<y; ) {
        if (f>=0) { f+=(ddFy+=2); --y; }
        ++x; ++(f+=(ddFx+=2));
        if (x!=y + 1) {
          const int x1 = x0 - y, x2 = x0 + y, y1 = y0 - x, y2 = y0 + x,
            x3 = x0 - x, x4 = x0 + x, y3 = y0 - y, y4 = y0 + y;
          draw_point(x1,y1,color,opacity).draw_point(x1,y2,color,opacity).
            draw_point(x2,y1,color,opacity).draw_point(x2,y2,color,opacity);
          if (x!=y)
            draw_point(x3,y3,color,opacity).draw_point(x4,y4,color,opacity).
              draw_point(x4,y3,color,opacity).draw_point(x3,y4,color,opacity);
        }
      }
      return *this;
    }

    //! Draw an image.
    /**
       \param sprite Sprite image.
       \param x0 X-coordinate of the sprite position.
       \param y0 Y-coordinate of the sprite position.
       \param z0 Z-coordinate of the sprite position.
       \param c0 C-coordinate of the sprite position.
       \param opacity Drawing opacity.
    **/
    template<typename t>
    CImg<T>& draw_image(const int x0, const int y0, const int z0, const int c0,
                        const CImg<t>& sprite, const float opacity=1) {
      if (is_empty() || !sprite) return *this;
      if (is_overlapped(sprite)) return draw_image(x0,y0,z0,c0,+sprite,opacity);
      if (x0==0 && y0==0 && z0==0 && c0==0 && is_sameXYZC(sprite) && opacity>=1 && !is_shared())
        return assign(sprite,false);
      const bool bx = x0<0, by = y0<0, bz = z0<0, bc = c0<0;
      const int
        dx0 = bx?0:x0, dy0 = by?0:y0, dz0 = bz?0:z0, dc0 = bc?0:c0,
        sx0 = dx0 - x0,  sy0 = dy0 - y0, sz0 = dz0 - z0, sc0 = dc0 - c0,
        lx = sprite.width() - sx0 - (x0 + sprite.width()>width()?x0 + sprite.width() - width():0),
        ly = sprite.height() - sy0 - (y0 + sprite.height()>height()?y0 + sprite.height() - height():0),
        lz = sprite.depth() - sz0 - (z0 + sprite.depth()>depth()?z0 + sprite.depth() - depth():0),
        lc = sprite.spectrum() - sc0 - (c0 + sprite.spectrum()>spectrum()?c0 + sprite.spectrum() - spectrum():0);

      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      if (lx>0 && ly>0 && lz>0 && lc>0) {
        for (int c = 0; c<lc; ++c)
          for (int z = 0; z<lz; ++z)
            for (int y = 0; y<ly; ++y) {
              T *ptrd = data(dx0,dy0 + y,dz0 + z,dc0 + c);
              const t *ptrs = sprite.data(sx0,sy0 + y,sz0 + z,sc0 + c);
              if (opacity>=1) for (int x = 0; x<lx; ++x) *(ptrd++) = (T)*(ptrs++);
              else for (int x = 0; x<lx; ++x) { *ptrd = (T)(nopacity*(*(ptrs++)) + *ptrd*copacity); ++ptrd; }
            }
      }
      return *this;
    }

    //! Draw an image \specialization.
    CImg<T>& draw_image(const int x0, const int y0, const int z0, const int c0,
                        const CImg<T>& sprite, const float opacity=1) {
      if (is_empty() || !sprite) return *this;
      if (is_overlapped(sprite)) return draw_image(x0,y0,z0,c0,+sprite,opacity);
      if (x0==0 && y0==0 && z0==0 && c0==0 && is_sameXYZC(sprite) && opacity>=1 && !is_shared())
        return assign(sprite,false);
      const bool bx = x0<0, by = y0<0, bz = z0<0, bc = c0<0;
      const int
        dx0 = bx?0:x0, dy0 = by?0:y0, dz0 = bz?0:z0, dc0 = bc?0:c0,
        sx0 = dx0 - x0,  sy0 = dy0 - y0, sz0 = dz0 - z0, sc0 = dc0 - c0,
        lx = sprite.width() - sx0 - (x0 + sprite.width()>width()?x0 + sprite.width() - width():0),
        ly = sprite.height() - sy0 - (y0 + sprite.height()>height()?y0 + sprite.height() - height():0),
        lz = sprite.depth() - sz0 - (z0 + sprite.depth()>depth()?z0 + sprite.depth() - depth():0),
        lc = sprite.spectrum() - sc0 - (c0 + sprite.spectrum()>spectrum()?c0 + sprite.spectrum() - spectrum():0);
      const ulongT slx = lx*sizeof(T);

      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      if (lx>0 && ly>0 && lz>0 && lc>0) {
        for (int c = 0; c<lc; ++c)
          for (int z = 0; z<lz; ++z)
            for (int y = 0; y<ly; ++y) {
              T *ptrd = data(dx0,dy0 + y,dz0 + z,dc0 + c);
              const T *ptrs = sprite.data(sx0,sy0 + y,sz0 + z,sc0 + c);
              if (opacity>=1) std::memcpy(ptrd,ptrs,slx);
              else for (int x = 0; x<lx; ++x) { *ptrd = (T)(nopacity*(*(ptrs++)) + *ptrd*copacity); ++ptrd; }
            }
      }
      return *this;
    }

    //! Draw an image \overload.
    template<typename t>
    CImg<T>& draw_image(const int x0, const int y0, const int z0,
                        const CImg<t>& sprite, const float opacity=1) {
      return draw_image(x0,y0,z0,0,sprite,opacity);
    }

    //! Draw an image \overload.
    template<typename t>
    CImg<T>& draw_image(const int x0, const int y0,
                        const CImg<t>& sprite, const float opacity=1) {
      return draw_image(x0,y0,0,sprite,opacity);
    }

    //! Draw an image \overload.
    template<typename t>
    CImg<T>& draw_image(const int x0,
                        const CImg<t>& sprite, const float opacity=1) {
      return draw_image(x0,0,sprite,opacity);
    }

    //! Draw an image \overload.
    template<typename t>
    CImg<T>& draw_image(const CImg<t>& sprite, const float opacity=1) {
      return draw_image(0,sprite,opacity);
    }

    //! Draw a masked image.
    /**
       \param sprite Sprite image.
       \param mask Mask image.
       \param x0 X-coordinate of the sprite position in the image instance.
       \param y0 Y-coordinate of the sprite position in the image instance.
       \param z0 Z-coordinate of the sprite position in the image instance.
       \param c0 C-coordinate of the sprite position in the image instance.
       \param mask_max_value Maximum pixel value of the mask image \c mask.
       \param opacity Drawing opacity.
       \note
       - Pixel values of \c mask set the opacity of the corresponding pixels in \c sprite.
       - Dimensions along x,y and z of \p sprite and \p mask must be the same.
    **/
    template<typename ti, typename tm>
    CImg<T>& draw_image(const int x0, const int y0, const int z0, const int c0,
                        const CImg<ti>& sprite, const CImg<tm>& mask, const float opacity=1,
                        const float mask_max_value=1) {
      if (is_empty() || !sprite || !mask) return *this;
      if (is_overlapped(sprite)) return draw_image(x0,y0,z0,c0,+sprite,mask,opacity,mask_max_value);
      if (is_overlapped(mask)) return draw_image(x0,y0,z0,c0,sprite,+mask,opacity,mask_max_value);
      if (mask._width!=sprite._width || mask._height!=sprite._height || mask._depth!=sprite._depth)
        throw CImgArgumentException(_cimg_instance
                                    "draw_image(): Sprite (%u,%u,%u,%u,%p) and mask (%u,%u,%u,%u,%p) have "
                                    "incompatible dimensions.",
                                    cimg_instance,
                                    sprite._width,sprite._height,sprite._depth,sprite._spectrum,sprite._data,
                                    mask._width,mask._height,mask._depth,mask._spectrum,mask._data);

      const bool bx = x0<0, by = y0<0, bz = z0<0, bc = c0<0;
      const int
        dx0 = bx?0:x0, dy0 = by?0:y0, dz0 = bz?0:z0, dc0 = bc?0:c0,
        sx0 = dx0 - x0,  sy0 = dy0 - y0, sz0 = dz0 - z0, sc0 = dc0 - c0,
        lx = sprite.width() - sx0 - (x0 + sprite.width()>width()?x0 + sprite.width() - width():0),
        ly = sprite.height() - sy0 - (y0 + sprite.height()>height()?y0 + sprite.height() - height():0),
        lz = sprite.depth() - sz0 - (z0 + sprite.depth()>depth()?z0 + sprite.depth() - depth():0),
        lc = sprite.spectrum() - sc0 - (c0 + sprite.spectrum()>spectrum()?c0 + sprite.spectrum() - spectrum():0);
      const ulongT msize = mask.size();

      if (lx>0 && ly>0 && lz>0 && lc>0) {
        for (int c = 0; c<lc; ++c)
          for (int z = 0; z<lz; ++z)
            for (int y = 0; y<ly; ++y) {
              T *ptrd = data(dx0,dy0 + y,dz0 + z,dc0 + c);
              const ti *ptrs = sprite.data(sx0,sy0 + y,sz0 + z,sc0 + c);
              const tm *ptrm = mask._data + (mask.offset(sx0,sy0 + y,sz0 + z,sc0 + c)%msize);
              for (int x = 0; x<lx; ++x) {
                const float mopacity = (float)(*(ptrm++)*opacity),
                  nopacity = cimg::abs(mopacity), copacity = mask_max_value - std::max(mopacity,0.f);
                *ptrd = (T)((nopacity*(*(ptrs++)) + *ptrd*copacity)/mask_max_value);
                ++ptrd;
              }
            }
      }
      return *this;
    }

    //! Draw a masked image \overload.
    template<typename ti, typename tm>
    CImg<T>& draw_image(const int x0, const int y0, const int z0,
                        const CImg<ti>& sprite, const CImg<tm>& mask, const float opacity=1,
                        const float mask_max_value=1) {
      return draw_image(x0,y0,z0,0,sprite,mask,opacity,mask_max_value);
    }

    //! Draw a image \overload.
    template<typename ti, typename tm>
    CImg<T>& draw_image(const int x0, const int y0,
                        const CImg<ti>& sprite, const CImg<tm>& mask, const float opacity=1,
                        const float mask_max_value=1) {
      return draw_image(x0,y0,0,sprite,mask,opacity,mask_max_value);
    }

    //! Draw a image \overload.
    template<typename ti, typename tm>
    CImg<T>& draw_image(const int x0,
                        const CImg<ti>& sprite, const CImg<tm>& mask, const float opacity=1,
                        const float mask_max_value=1) {
      return draw_image(x0,0,sprite,mask,opacity,mask_max_value);
    }

    //! Draw an image.
    template<typename ti, typename tm>
    CImg<T>& draw_image(const CImg<ti>& sprite, const CImg<tm>& mask, const float opacity=1,
                        const float mask_max_value=1) {
      return draw_image(0,sprite,mask,opacity,mask_max_value);
    }

    //! Draw a text string.
    /**
       \param x0 X-coordinate of the text in the image instance.
       \param y0 Y-coordinate of the text in the image instance.
       \param text Format of the text ('printf'-style format string).
       \param foreground_color Pointer to \c spectrum() consecutive values, defining the foreground drawing color.
       \param background_color Pointer to \c spectrum() consecutive values, defining the background drawing color.
       \param opacity Drawing opacity.
       \param font Font used for drawing text.
    **/
    template<typename tc1, typename tc2, typename t>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const tc1 *const foreground_color, const tc2 *const background_color,
                       const float opacity, const CImgList<t>* const font, ...) {
      if (!font || !*font) return *this;
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      return _draw_text(x0,y0,tmp,foreground_color,background_color,opacity,*font,false);
    }

    //! Draw a text string \overload.
    /**
       \note A transparent background is used for the text.
    **/
    template<typename tc, typename t>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const tc *const foreground_color, const int,
                       const float opacity, const CImgList<t>* const font, ...) {
      if (!font || !*font) return *this;
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      return _draw_text(x0,y0,tmp,foreground_color,(tc*)0,opacity,*font,false);
    }

    //! Draw a text string \overload.
    /**
       \note A transparent foreground is used for the text.
    **/
    template<typename tc, typename t>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const int, const tc *const background_color,
                       const float opacity, const CImgList<t>* const font, ...) {
      if (!font || !*font) return *this;
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      return _draw_text(x0,y0,tmp,(tc*)0,background_color,opacity,*font,false);
    }

    //! Draw a text string \overload.
    /**
       \param x0 X-coordinate of the text in the image instance.
       \param y0 Y-coordinate of the text in the image instance.
       \param text Format of the text ('printf'-style format string).
       \param foreground_color Array of spectrum() values of type \c T,
         defining the foreground color (0 means 'transparent').
       \param background_color Array of spectrum() values of type \c T,
         defining the background color (0 means 'transparent').
       \param opacity Drawing opacity.
       \param font_height Height of the text font (exact match for 13,32,64,128, interpolated otherwise).
       \note To ensure thread-safety, this function uses a mutex lock. For real multi-threaded drawing of text,
       use another version of \c CImg<T>::draw_text() with argument `font`, that must be a copy of what is returned
       by \c CImgList<T>::font().
    **/
    template<typename tc1, typename tc2>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const tc1 *const foreground_color, const tc2 *const background_color,
                       const float opacity=1, const unsigned int font_height=13, ...) {
      if (!font_height) return *this;
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font_height); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      cimg::mutex(15);
      const CImgList<ucharT>& font = CImgList<ucharT>::font(font_height,true);
      _draw_text(x0,y0,tmp,foreground_color,background_color,opacity,font,true);
      cimg::mutex(15,0);
      return *this;
    }

    //! Draw a text string \overload.
    template<typename tc>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const tc *const foreground_color, const int background_color=0,
                       const float opacity=1, const unsigned int font_height=13, ...) {
      if (!font_height) return *this;
      cimg::unused(background_color);
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font_height); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      return draw_text(x0,y0,"%s",foreground_color,(const tc*)0,opacity,font_height,tmp._data);
    }

    //! Draw a text string \overload.
    template<typename tc>
    CImg<T>& draw_text(const int x0, const int y0,
                       const char *const text,
                       const int, const tc *const background_color,
                       const float opacity=1, const unsigned int font_height=13, ...) {
      if (!font_height) return *this;
      CImg<charT> tmp(2048);
      std::va_list ap; va_start(ap,font_height); cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      return draw_text(x0,y0,"%s",(tc*)0,background_color,opacity,font_height,tmp._data);
    }

    template<typename tc1, typename tc2, typename t>
    CImg<T>& _draw_text(const int x0, const int y0,
                        const char *const text,
                        const tc1 *const foreground_color, const tc2 *const background_color,
                        const float opacity, const CImgList<t>& font,
                        const bool is_native_font) {
      if (!text || !font) return *this;
      const unsigned int text_length = (unsigned int)std::strlen(text);
      const int padding_x = font[0]._height<48?1:font[0]._height<128?(int)std::ceil(font[0]._height/51.f + 0.745f):4;
      unsigned char o_ch, ch = 0;
      int x, y, w;
      CImg<intT> left_paddings(text_length,1,1,1,0);
      const CImg<t> empty = CImg<t>::empty();

      if (is_empty() || is_native_font) {
        // Pre-compute necessary size of the image as well as left paddings of each character.
        x = y = w = 0;
        o_ch = 0;
        for (unsigned int i = 0; i<text_length; ++i) {
          ch = (unsigned char)text[i];
          switch (ch) {
          case '\n' :
            if (font._width>10) y+=font[10]._height; else y+=font[0]._height;
            if (x>w) w = x;
            x = 0;
            break;
          case '\t' :
            if (font._width>32) x+=4*font[32]._width; else x+=4*font[0]._width;
            break;
          case ' ' :
            if (font._width>32) x+=font[32]._width; else x+=font[0]._width;
            break;
          default : if (ch<font._width) {
              int left_padding = 0;
              if (is_native_font && font[0]._height<128) { /// Determine left padding for native fonts
                if (ch==':' || ch=='!' || ch=='.' || ch==';')
                  left_padding = 2*padding_x;
                else if (o_ch==',' || (o_ch=='.' && (ch<'0' || ch>'9')) || o_ch==';' || o_ch==':' || o_ch=='!')
                  left_padding = 4*padding_x;
                else if (((o_ch=='i' || o_ch=='l' || o_ch=='I' || o_ch=='J' || o_ch=='M' || o_ch=='N') &&
                          ((ch>='0' && ch<='9') ||
                           (ch>='a' && ch<='z' && ch!='v' && ch!='x' && ch!='y') ||
                           (ch>='B' && ch<='Z' && ch!='J' && ch!='T' && ch!='V' && ch!='X' && ch!='Y'))) ||
                         o_ch=='.' || o_ch=='\'' || ch=='\'')
                  left_padding = padding_x;
                else if ((o_ch<'0' || o_ch>'9') && ch!='-') {
                  const CImg<t> &mask = ch + 256U<font._width?font[ch + 256]:empty;
                  if (o_ch && ch>' ' && o_ch>' ' && mask._height>13) {
                    const CImg<t> &o_mask = o_ch + 256U<font._width?font[o_ch + 256]:empty;
                    if (o_mask._height>13) {
                      const int w1 = mask.width()>0?o_mask.width() - 1:0, w2 = w1>1?w1 - 1:0, w3 = w2>1?w2 - 1:0;
                      left_padding = -10;
                      cimg_forY(mask,k) {
                        const int
                          lpad = o_mask(w1,k)>=8?0:
                                 o_mask._width<=2 || o_mask(w2,k)>=8?-1:
                                 o_mask._width<=3 || o_mask(w3,k)>=8?-2:-3,
                          rpad = mask(0,k)>=8?0:
                                 mask._width<=2 || mask(1,k)>=8?-1:
                                 mask._width<=3 || mask(2,k)>=8?-2:-3;
                        left_padding = std::max(left_padding,lpad + rpad);
                      }
                    }
                  }
                }
                left_paddings[i] = left_padding;
              }
              x+=left_padding + font[ch]._width + padding_x;
              o_ch = ch;
            }
          }
        }
        if (x!=0 || ch=='\n') { if (x>w) w = x; y+=font[0]._height; }
        if (is_empty()) assign(std::max(0,x0 + w),std::max(0,y0 + y),1,is_native_font?1:font[0]._spectrum,(T)0);
      }

      // Draw font characters on image.
      x = x0; y = y0;
      for (unsigned int i = 0; i<text_length; ++i) {
        ch = (unsigned char)text[i];
        switch (ch) {
        case '\n' :
          if (font._width>10) y+=font[10]._height; else y+=font[0]._height;
          x = x0;
          break;
        case '\t' :
        case ' ' : {
          const unsigned int
            lw = (ch=='\t'?4:1)*font[font._width>32?32:0]._width,
            lh = font[font._width>32?32:0]._height;
          if (background_color) draw_rectangle(x,y,x + lw - 1,y + lh - 1,background_color,opacity);
          x+=lw;
        } break;
        default : if (ch<font._width) {
            if (font[ch]) {
              CImg<T> letter = font[ch];
              const CImg<t> &mask = ch + 256U<font._width?font[ch + 256]:empty;
              const int posx = x + left_paddings[i] + padding_x;

              for (unsigned int c = 0; c<_spectrum; c+=letter._spectrum) {
                if (c) letter = font[ch];
                const unsigned int cmin = std::min(_spectrum - c,letter._spectrum);
                for (unsigned int d = 0; d<cmin; ++d)
                  if (foreground_color[c + d]!=255)
                    letter.get_shared_channel(d)*=foreground_color[c + d]/255.f;

                if (mask) { // Letter with alpha
                  if (background_color)
                    for (unsigned int d = 0; d<cmin; ++d)
                      draw_rectangle(x,y,0,c + d,posx + letter._width - 1,y + letter._height - 1,0,c + d,
                                     background_color[c + d],opacity);
                  draw_image(posx,y,0,c,letter,mask,opacity,255.f);
                } else // Letter without alpha
                  draw_image(posx,y,0,c,letter,opacity);
              }
              x = posx + letter._width;
            }
          }
        }
      }
      return *this;
    }

    // [internal] Version used to display text in interactive viewers.
    CImg<T>& __draw_text(const char *const text, unsigned int &font_size, const int is_down, ...) {
      CImg<charT> tmp(2048);
      std::va_list ap;
      va_start(ap,is_down);
      cimg_vsnprintf(tmp,tmp._width,text,ap); va_end(ap);
      CImg<ucharT> a_label, a_labelmask;
      const unsigned char a_labelcolor = 255;
      unsigned int ofs = font_size, fs = ofs;
      do { // Determine best font size
        a_label.assign().draw_text(0,0,"%s",&a_labelcolor,0,1,fs,tmp._data);
        if (a_label._width<7*_width/10 && a_label._height>_height/20 && a_label._height<_height/5) {
          font_size = fs; break;
        } else if ((a_label._width>7*_width/10 || a_label._height>_height/5) && fs>13 && ofs>=fs) {
          ofs = fs; fs = std::max(13U,(unsigned int)cimg::round(fs/1.25f));
        } else if (a_label._width<3*_width/10 && a_label._height<_height/20 && fs<64 && ofs<=fs) {
          ofs = fs; fs = std::min(64U,(unsigned int)cimg::round(fs*1.25f));
        } else { font_size = fs; break; }
      } while (true);
      a_label.normalize(0,255);
      a_label+=(255 - a_label.get_dilate(3)).normalize(0,80);
      a_label.resize(-100,-100,1,3,1);
      return draw_image(0,is_down?height() - a_label.height():0,a_label,0.85f);
    }

    //! Draw a 2D vector field.
    /**
       \param flow Image of 2D vectors used as input data.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param sampling Length (in pixels) between each arrow.
       \param factor Length factor of each arrow (if <0, computed as a percentage of the maximum length).
       \param is_arrow Indicates whether arrows must be drawn, instead of oriented segments.
       \param pattern Used pattern to draw lines.
       \note Clipping is supported.
    **/
    template<typename t1, typename t2>
    CImg<T>& draw_quiver(const CImg<t1>& flow,
                         const t2 *const color, const float opacity=1,
                         const unsigned int sampling=25, const float factor=-20,
                         const bool is_arrow=true, const unsigned int pattern=~0U) {
      return draw_quiver(flow,CImg<t2>(color,_spectrum,1,1,1,true),opacity,sampling,factor,is_arrow,pattern);
    }

    //! Draw a 2D vector field using a field of colors.
    /**
       \param flow Image of 2D vectors used as input data.
       \param color Image of spectrum()-D vectors corresponding to the color of each arrow.
       \param opacity Opacity of the drawing.
       \param sampling Length (in pixels) between each arrow.
       \param factor Length factor of each arrow (if <0, computed as a percentage of the maximum length).
       \param is_arrow Indicates whether arrows must be drawn, instead of oriented segments.
       \param pattern Used pattern to draw lines.
       \note Clipping is supported.
    **/
    template<typename t1, typename t2>
    CImg<T>& draw_quiver(const CImg<t1>& flow,
                         const CImg<t2>& color, const float opacity=1,
                         const unsigned int sampling=25, const float factor=-20,
                         const bool is_arrow=true, const unsigned int pattern=~0U) {
      if (is_empty()) return *this;
      if (!flow || flow._spectrum!=2)
        throw CImgArgumentException(_cimg_instance
                                    "draw_quiver(): Invalid dimensions of specified flow (%u,%u,%u,%u,%p).",
                                    cimg_instance,
                                    flow._width,flow._height,flow._depth,flow._spectrum,flow._data);
      if (sampling<=0)
        throw CImgArgumentException(_cimg_instance
                                    "draw_quiver(): Invalid sampling value %g "
                                    "(should be >0)",
                                    cimg_instance,
                                    sampling);
      const bool colorfield = (color._width==flow._width && color._height==flow._height &&
                               color._depth==1 && color._spectrum==_spectrum);
      if (is_overlapped(flow)) return draw_quiver(+flow,color,opacity,sampling,factor,is_arrow,pattern);
      float vmax,fact;
      if (factor<=0) {
        float m, M = (float)flow.get_norm(2).max_min(m);
        vmax = (float)std::max(cimg::abs(m),cimg::abs(M));
        if (!vmax) vmax = 1;
        fact = -factor;
      } else { fact = factor; vmax = 1; }

      for (unsigned int y = sampling/2; y<_height; y+=sampling)
        for (unsigned int x = sampling/2; x<_width; x+=sampling) {
          const unsigned int X = x*flow._width/_width, Y = y*flow._height/_height;
          float u = (float)flow(X,Y,0,0)*fact/vmax, v = (float)flow(X,Y,0,1)*fact/vmax;
          if (is_arrow) {
            const int xx = (int)(x + u), yy = (int)(y + v);
            if (colorfield) draw_arrow(x,y,xx,yy,color.get_vector_at(X,Y)._data,opacity,45,sampling/5.f,pattern);
            else draw_arrow(x,y,xx,yy,color._data,opacity,45,sampling/5.f,pattern);
          } else {
            if (colorfield)
              draw_line((int)(x - 0.5*u),(int)(y - 0.5*v),(int)(x + 0.5*u),(int)(y + 0.5*v),
                        color.get_vector_at(X,Y)._data,opacity,pattern);
            else draw_line((int)(x - 0.5*u),(int)(y - 0.5*v),(int)(x + 0.5*u),(int)(y + 0.5*v),
                           color._data,opacity,pattern);
          }
        }
      return *this;
    }

    //! Draw a labeled horizontal axis.
    /**
       \param values_x Values along the horizontal axis.
       \param y Y-coordinate of the horizontal axis in the image instance.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern Drawing pattern.
       \param font_height Height of the labels (exact match for 13,23,53,103, interpolated otherwise).
       \param allow_zero Enable/disable the drawing of label '0' if found.
       \param round_x
    **/
    template<typename t, typename tc>
    CImg<T>& draw_axis(const CImg<t>& values_x, const int y,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern=~0U, const unsigned int font_height=13,
                       const bool allow_zero=true, const float round_x=0) {
      if (is_empty()) return *this;
      const int yt = (y + 3 + font_height)<_height?y + 3:y - 2 - (int)font_height;
      const int siz = (int)values_x.size() - 1;
      CImg<charT> txt(32);
      CImg<T> a_label;
      if (siz<=0) { // Degenerated case
        draw_line(0,y,_width - 1,y,color,opacity,pattern);
        if (!siz) {
          cimg_snprintf(txt,txt._width,"%g",round_x?cimg::round((double)*values_x,round_x):(double)*values_x);
          a_label.assign().draw_text(0,0,txt,color,(tc*)0,opacity,font_height);
          const int
            _xt = (width() - a_label.width())/2,
            xt = _xt<3?3:_xt + a_label.width()>=width() - 2?width() - 3 - a_label.width():_xt;
          draw_point(width()/2,y - 1,color,opacity).draw_point(width()/2,y + 1,color,opacity);
          if (allow_zero || *txt!='0' || txt[1]!=0)
            draw_text(xt,yt,txt,color,(tc*)0,opacity,font_height);
        }
      } else { // Regular case
        if (values_x[0]<values_x[siz]) draw_arrow(0,y,_width - 1,y,color,opacity,30,5,pattern);
        else draw_arrow(_width - 1,y,0,y,color,opacity,30,5,pattern);
        cimg_foroff(values_x,x) {
          cimg_snprintf(txt,txt._width,"%g",round_x?cimg::round((double)values_x(x),round_x):(double)values_x(x));
          a_label.assign().draw_text(0,0,txt,color,(tc*)0,opacity,font_height);
          const int
            xi = (int)(x*(_width - 1)/siz),
            _xt = xi - a_label.width()/2,
            xt = _xt<3?3:_xt + a_label.width()>=width() - 2?width() - 3 - a_label.width():_xt;
          draw_point(xi,y - 1,color,opacity).draw_point(xi,y + 1,color,opacity);
          if (allow_zero || *txt!='0' || txt[1]!=0)
            draw_text(xt,yt,txt,color,(tc*)0,opacity,font_height);
        }
      }
      return *this;
    }

    //! Draw a labeled vertical axis.
    /**
       \param x X-coordinate of the vertical axis in the image instance.
       \param values_y Values along the Y-axis.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern Drawing pattern.
       \param font_height Height of the labels (exact match for 13,23,53,103, interpolated otherwise).
       \param allow_zero Enable/disable the drawing of label '0' if found.
       \param round_y
    **/
    template<typename t, typename tc>
    CImg<T>& draw_axis(const int x, const CImg<t>& values_y,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern=~0U, const unsigned int font_height=13,
                       const bool allow_zero=true, const float round_y=0) {
      if (is_empty()) return *this;
      int siz = (int)values_y.size() - 1;
      CImg<charT> txt(32);
      CImg<T> a_label;
      if (siz<=0) { // Degenerated case
        draw_line(x,0,x,_height - 1,color,opacity,pattern);
        if (!siz) {
          cimg_snprintf(txt,txt._width,"%g",round_y?cimg::round((double)*values_y,round_y):(double)*values_y);
          a_label.assign().draw_text(0,0,txt,color,(tc*)0,opacity,font_height);
          const int
            _yt = (height() - a_label.height())/2,
            yt = _yt<0?0:_yt + a_label.height()>=height()?height() - 1 - a_label.height():_yt,
            _xt = x - 2 - a_label.width(),
            xt = _xt>=0?_xt:x + 3;
          draw_point(x - 1,height()/2,color,opacity).draw_point(x + 1,height()/2,color,opacity);
          if (allow_zero || *txt!='0' || txt[1]!=0)
            draw_text(xt,yt,txt,color,(tc*)0,opacity,font_height);
        }
      } else { // Regular case
        if (values_y[0]<values_y[siz]) draw_arrow(x,0,x,_height - 1,color,opacity,30,5,pattern);
        else draw_arrow(x,_height - 1,x,0,color,opacity,30,5,pattern);
        cimg_foroff(values_y,y) {
          cimg_snprintf(txt,txt._width,"%g",round_y?cimg::round((double)values_y(y),round_y):(double)values_y(y));
          a_label.assign().draw_text(0,0,txt,color,(tc*)0,opacity,font_height);
          const int
            yi = (int)(y*(_height - 1)/siz),
            _yt = yi - a_label.height()/2,
            yt = _yt<0?0:_yt + a_label.height()>=height()?height() - 1 - a_label.height():_yt,
            _xt = x - 2 - a_label.width(),
            xt = _xt>=0?_xt:x + 3;
          draw_point(x - 1,yi,color,opacity).draw_point(x + 1,yi,color,opacity);
          if (allow_zero || *txt!='0' || txt[1]!=0)
            draw_text(xt,yt,txt,color,(tc*)0,opacity,font_height);
        }
      }
      return *this;
    }

    //! Draw labeled horizontal and vertical axes.
    /**
       \param values_x Values along the X-axis.
       \param values_y Values along the Y-axis.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern_x Drawing pattern for the X-axis.
       \param pattern_y Drawing pattern for the Y-axis.
       \param font_height Height of the labels (exact match for 13,23,53,103, interpolated otherwise).
       \param allow_zero Enable/disable the drawing of label '0' if found.
       \param round_x
       \param round_y
    **/
    template<typename tx, typename ty, typename tc>
    CImg<T>& draw_axes(const CImg<tx>& values_x, const CImg<ty>& values_y,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern_x=~0U, const unsigned int pattern_y=~0U,
                       const unsigned int font_height=13, const bool allow_zero=true,
                       const float round_x=0, const float round_y=0) {
      if (is_empty()) return *this;
      const CImg<tx> nvalues_x(values_x._data,values_x.size(),1,1,1,true);
      const int sizx = (int)values_x.size() - 1, wm1 = std::max(1,width() - 1);
      if (sizx>=0) {
        float ox = (float)*nvalues_x;
        for (unsigned int x = sizx?1U:0U; x<_width; ++x) {
          const float nx = (float)nvalues_x._linear_atX((float)x*sizx/wm1);
          if (nx*ox<=0) {
            draw_axis(nx==0?x:x - 1,values_y,color,opacity,pattern_y,font_height,allow_zero,round_y);
            break;
          }
          ox = nx;
        }
      }
      const CImg<ty> nvalues_y(values_y._data,values_y.size(),1,1,1,true);
      const int sizy = (int)values_y.size() - 1, hm1 = height() - 1;
      if (sizy>0) {
        float oy = (float)nvalues_y[0];
        for (unsigned int y = sizy?1U:0U; y<_height; ++y) {
          const float ny = (float)nvalues_y._linear_atX((float)y*sizy/hm1);
          if (ny*oy<=0) {
            draw_axis(values_x,ny==0?y:y - 1,color,opacity,pattern_x,font_height,allow_zero,round_x);
            break;
          }
          oy = ny;
        }
      }
      return *this;
    }

    //! Draw labeled horizontal and vertical axes \overload.
    template<typename tc>
    CImg<T>& draw_axes(const float x0, const float x1, const float y0, const float y1,
                       const tc *const color, const float opacity=1,
                       const int subdivisionx=-60, const int subdivisiony=-60,
                       const float precisionx=0, const float precisiony=0,
                       const unsigned int pattern_x=~0U, const unsigned int pattern_y=~0U,
                       const unsigned int font_height=13) {
      if (is_empty()) return *this;
      const bool allow_zero = (x0*x1>0) || (y0*y1>0);
      const float
        dx = cimg::abs(x1 - x0), dy = cimg::abs(y1 - y0),
        px = dx<=0?1:precisionx==0?(float)std::pow(10.,(int)std::log10(dx) - 2.):precisionx,
        py = dy<=0?1:precisiony==0?(float)std::pow(10.,(int)std::log10(dy) - 2.):precisiony;
      if (x0!=x1 && y0!=y1)
        draw_axes(CImg<floatT>::sequence(subdivisionx>0?subdivisionx:1-width()/subdivisionx,x0,x1),
                  CImg<floatT>::sequence(subdivisiony>0?subdivisiony:1-height()/subdivisiony,y0,y1),
                  color,opacity,pattern_x,pattern_y,font_height,allow_zero,px,py);
      else if (x0==x1 && y0!=y1)
        draw_axis((int)x0,CImg<floatT>::sequence(subdivisiony>0?subdivisiony:1-height()/subdivisiony,y0,y1),
                  color,opacity,pattern_y,font_height,py);
      else if (x0!=x1 && y0==y1)
        draw_axis(CImg<floatT>::sequence(subdivisionx>0?subdivisionx:1-width()/subdivisionx,x0,x1),(int)y0,
                  color,opacity,pattern_x,font_height,px);
      return *this;
    }

    //! Draw a 2D grid.
    /**
       \param values_x X-coordinates of the vertical lines.
       \param values_y Y-coordinates of the horizontal lines.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
       \param pattern_x Drawing pattern for vertical lines.
       \param pattern_y Drawing pattern for horizontal lines.
    **/
    template<typename tx, typename ty, typename tc>
    CImg<T>& draw_grid(const CImg<tx>& values_x, const CImg<ty>& values_y,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern_x=~0U, const unsigned int pattern_y=~0U) {
      if (is_empty()) return *this;
      if (values_x) cimg_foroff(values_x,x) {
          const int xi = (int)values_x[x];
          if (xi>=0 && xi<width()) draw_line(xi,0,xi,_height - 1,color,opacity,pattern_x);
        }
      if (values_y) cimg_foroff(values_y,y) {
          const int yi = (int)values_y[y];
          if (yi>=0 && yi<height()) draw_line(0,yi,_width - 1,yi,color,opacity,pattern_y);
        }
      return *this;
    }

    //! Draw a 2D grid \overload.
    template<typename tc>
    CImg<T>& draw_grid(const float delta_x,  const float delta_y,
                       const float offsetx, const float offsety,
                       const bool invertx, const bool inverty,
                       const tc *const color, const float opacity=1,
                       const unsigned int pattern_x=~0U, const unsigned int pattern_y=~0U) {
      if (is_empty()) return *this;
      CImg<uintT> seqx, seqy;
      if (delta_x!=0) {
        const float dx = delta_x>0?delta_x:_width*-delta_x/100;
        const unsigned int nx = (unsigned int)(_width/std::max(1.0f,dx));
        seqx = CImg<uintT>::sequence(1 + nx,0,(unsigned int)(dx*nx));
        if (offsetx) cimg_foroff(seqx,x) seqx(x) = (unsigned int)cimg::mod(seqx(x) + offsetx,(float)_width);
        if (invertx) cimg_foroff(seqx,x) seqx(x) = _width - 1 - seqx(x);
      }
      if (delta_y!=0) {
        const float dy = delta_y>0?delta_y:_height*-delta_y/100;
        const unsigned int ny = (unsigned int)(_height/std::max(1.0f,dy));
        seqy = CImg<uintT>::sequence(1 + ny,0,(unsigned int)(dy*ny));
        if (offsety) cimg_foroff(seqy,y) seqy(y) = (unsigned int)cimg::mod(seqy(y) + offsety,(float)_height);
        if (inverty) cimg_foroff(seqy,y) seqy(y) = _height - 1 - seqy(y);
     }
      return draw_grid(seqx,seqy,color,opacity,pattern_x,pattern_y);
    }

    //! Draw a 1D graph.
    /**
       \param data Image containing the graph values I = f(x).
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.

       \param plot_type Define the plot type:
                      - 0 = No plot.
                      - 1 = Plot using segments.
                      - 2 = Plot using cubic splines.
                      - 3 = Plot with bars.
       \param vertex_type Define the type of points:
                      - 0 = No points.
                      - 1 = Point.
                      - 2 = Straight cross.
                      - 3 = Diagonal cross.
                      - 4 = Filled circle.
                      - 5 = Outlined circle.
                      - 6 = Square.
                      - 7 = Diamond.
       \param ymin Lower bound of the y-range.
       \param ymax Upper bound of the y-range.
       \param pattern Drawing pattern.
       \note
         - if \c ymin==ymax==0, the y-range is computed automatically from the input samples.
    **/
    template<typename t, typename tc>
    CImg<T>& draw_graph(const CImg<t>& data,
                        const tc *const color, const float opacity=1,
                        const unsigned int plot_type=1, const int vertex_type=1,
                        const double ymin=0, const double ymax=0, const unsigned int pattern=~0U) {
      if (is_empty() || _height<=1 || !data || !opacity) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_graph(): Specified color is (null).",
                                    cimg_instance);

      // Create shaded colors for displaying bar plots.
      CImg<tc> color1, color2;
      if (plot_type==3) {
        color1.assign(_spectrum); color2.assign(_spectrum);
        cimg_forC(*this,c) {
          color1[c] = (tc)std::min((float)cimg::type<tc>::max(),(float)color[c]*1.2f);
          color2[c] = (tc)(color[c]*0.4f);
        }
      }

      // Compute min/max and normalization factors.
      const ulongT
        siz = data.size(),
        _siz1 = siz - (plot_type!=3),
        siz1 = _siz1?_siz1:1;
      const unsigned int
        _width1 = _width - (plot_type!=3),
        width1 = _width1?_width1:1;
      double m = ymin, M = ymax;
      if (ymin==ymax) m = (double)data.max_min(M);
      if (m==M) { --m; ++M; }
      const float ca = (float)(M-m)/(_height - 1);
      bool init_hatch = true;

      // Draw graph edges.
      switch (plot_type%4) {
      case 1 : { // Segments
        int oX = 0, oY = (int)cimg::round((data[0] - m)/ca);
        if (siz==1) {
          const int Y = (int)cimg::round((*data - m)/ca);
          draw_line(0,Y,width() - 1,Y,color,opacity,pattern);
        } else {
          const float fx = (float)_width/siz1;
          for (ulongT off = 1; off<siz; ++off) {
            const int
              X = (int)cimg::round(off*fx) - 1,
              Y = (int)cimg::round((data[off]-m)/ca);
            draw_line(oX,oY,X,Y,color,opacity,pattern,init_hatch);
            oX = X; oY = Y;
            init_hatch = false;
          }
        }
      } break;
      case 2 : { // Spline
        const CImg<t> ndata(data._data,siz,1,1,1,true);
        int oY = (int)cimg::round((data[0] - m)/ca);
        cimg_forX(*this,x) {
          const int Y = (int)cimg::round((ndata._cubic_atX((float)x*siz1/width1)-m)/ca);
          if (x>0) draw_line(x,oY,x + 1,Y,color,opacity,pattern,init_hatch);
          init_hatch = false;
          oY = Y;
        }
      } break;
      case 3 : { // Bars
        const int Y0 = (int)cimg::round(-m/ca);
        const float fx = (float)_width/siz1;
        int oX = 0;
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round((off + 1)*fx) - 1,
            Y = (int)cimg::round((data[off] - m)/ca);
          draw_rectangle(oX,Y0,X,Y,color,opacity).
            draw_line(oX,Y,oX,Y0,color2.data(),opacity).
            draw_line(oX,Y0,X,Y0,Y<=Y0?color2.data():color1.data(),opacity).
            draw_line(X,Y,X,Y0,color1.data(),opacity).
            draw_line(oX,Y,X,Y,Y<=Y0?color1.data():color2.data(),opacity);
          oX = X + 1;
        }
      } break;
      default : break; // No edges
      }

      // Draw graph points.
      const unsigned int wb2 = plot_type==3?_width1/(2*siz):0;
      const float fx = (float)_width1/siz1;
      switch (vertex_type%8) {
      case 1 : { // Point
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_point(X,Y,color,opacity);
        }
      } break;
      case 2 : { // Straight Cross
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_line(X - 3,Y,X + 3,Y,color,opacity).draw_line(X,Y - 3,X,Y + 3,color,opacity);
        }
      } break;
      case 3 : { // Diagonal Cross
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_line(X - 3,Y - 3,X + 3,Y + 3,color,opacity).draw_line(X - 3,Y + 3,X + 3,Y - 3,color,opacity);
        }
      } break;
      case 4 : { // Filled Circle
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_circle(X,Y,3,color,opacity);
        }
      } break;
      case 5 : { // Outlined circle
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_circle(X,Y,3,color,opacity,~0U);
        }
      } break;
      case 6 : { // Square
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_rectangle(X - 3,Y - 3,X + 3,Y + 3,color,opacity,~0U);
        }
      } break;
      case 7 : { // Diamond
        cimg_foroff(data,off) {
          const int
            X = (int)cimg::round(off*fx + wb2),
            Y = (int)cimg::round((data[off]-m)/ca);
          draw_line(X,Y - 4,X + 4,Y,color,opacity).
            draw_line(X + 4,Y,X,Y + 4,color,opacity).
            draw_line(X,Y + 4,X - 4,Y,color,opacity).
            draw_line(X - 4,Y,X,Y - 4,color,opacity);
        }
      } break;
      default : break; // No points
      }
      return *this;
    }

    bool _draw_fill(const int x, const int y, const int z,
                    const CImg<T>& ref, const float tolerance2) const {
      const T *ptr1 = data(x,y,z), *ptr2 = ref._data;
      const ulongT off = _width*_height*_depth;
      float diff = 0;
      cimg_forC(*this,c) { diff += cimg::sqr(*ptr1 - *(ptr2++)); ptr1+=off; }
      return diff<=tolerance2;
    }

    //! Fill a 3D region using the flood-fill algorithm.
    /**
       \param x0 X-coordinate of the starting point of the region to fill.
       \param y0 Y-coordinate of the starting point of the region to fill.
       \param z0 Z-coordinate of the starting point of the region to fill.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param[out] region Image that will contain the mask of the filled region [output].
       \param tolerance Tolerance concerning neighborhood values.
       \param opacity Opacity of the drawing.
       \param is_high_connectivity Indicates whether the algorithm uses low or high connectivity.
       \return \c region is initialized with the binary mask of the filled region.
    **/
    template<typename tc, typename t>
    CImg<T>& draw_fill(const int x0, const int y0, const int z0,
                        const tc *const color, const float opacity,
                        CImg<t> &region,
                        const float tolerance = 0,
                        const bool is_high_connectivity = false) {
#define _draw_fill_push(x,y,z) if (N>=stack._width) stack.resize(2*N + 1,1,1,3,0); \
                               stack[N] = x; stack(N,1) = y; stack(N++,2) = z
#define _draw_fill_pop(x,y,z) x = stack[--N]; y = stack(N,1); z = stack(N,2)
#define _draw_fill_is_inside(x,y,z) !_region(x,y,z) && _draw_fill(x,y,z,ref,tolerance2)

      if (!containsXYZC(x0,y0,z0,0)) return *this;
      const float nopacity = cimg::abs((float)opacity), copacity = 1 - std::max((float)opacity,0.f);
      const float tolerance2 = cimg::sqr(tolerance);
      const CImg<T> ref = get_vector_at(x0,y0,z0);
      CImg<uintT> stack(256,1,1,3);
      CImg<ucharT> _region(_width,_height,_depth,1,0);
      unsigned int N = 0;
      int x, y, z;

      _draw_fill_push(x0,y0,z0);
      while (N>0) {
        _draw_fill_pop(x,y,z);
        if (!_region(x,y,z)) {
          const int yp = y - 1, yn = y + 1, zp = z - 1, zn = z + 1;
          int xl = x, xr = x;

          // Using these booleans reduces the number of pushes drastically.
          bool is_yp = false, is_yn = false, is_zp = false, is_zn = false;
          for (int step = -1; step<2; step+=2) {
            while (x>=0 && x<width() && _draw_fill_is_inside(x,y,z)) {
              if (yp>=0 && _draw_fill_is_inside(x,yp,z)) {
                if (!is_yp) { _draw_fill_push(x,yp,z); is_yp = true; }
              } else is_yp = false;
              if (yn<height() && _draw_fill_is_inside(x,yn,z)) {
                if (!is_yn) { _draw_fill_push(x,yn,z); is_yn = true; }
              } else is_yn = false;
              if (depth()>1) {
                if (zp>=0 && _draw_fill_is_inside(x,y,zp)) {
                  if (!is_zp) { _draw_fill_push(x,y,zp); is_zp = true; }
                } else is_zp = false;
                if (zn<depth() && _draw_fill_is_inside(x,y,zn)) {
                  if (!is_zn) { _draw_fill_push(x,y,zn); is_zn = true; }
                } else is_zn = false;
              }
              if (is_high_connectivity) {
                const int xp = x - 1, xn = x + 1;
                if (yp>=0 && !is_yp) {
                  if (xp>=0 && _draw_fill_is_inside(xp,yp,z)) {
                    _draw_fill_push(xp,yp,z); if (step<0) is_yp = true;
                  }
                  if (xn<width() && _draw_fill_is_inside(xn,yp,z)) {
                    _draw_fill_push(xn,yp,z); if (step>0) is_yp = true;
                  }
                }
                if (yn<height() && !is_yn) {
                  if (xp>=0 && _draw_fill_is_inside(xp,yn,z)) {
                    _draw_fill_push(xp,yn,z); if (step<0) is_yn = true;
                  }
                  if (xn<width() && _draw_fill_is_inside(xn,yn,z)) {
                    _draw_fill_push(xn,yn,z); if (step>0) is_yn = true;
                  }
                }
                if (depth()>1) {
                  if (zp>=0 && !is_zp) {
                    if (xp>=0 && _draw_fill_is_inside(xp,y,zp)) {
                      _draw_fill_push(xp,y,zp); if (step<0) is_zp = true;
                    }
                    if (xn<width() && _draw_fill_is_inside(xn,y,zp)) {
                      _draw_fill_push(xn,y,zp); if (step>0) is_zp = true;
                    }

                    if (yp>=0 && !is_yp) {
                      if (_draw_fill_is_inside(x,yp,zp)) { _draw_fill_push(x,yp,zp); }
                      if (xp>=0 && _draw_fill_is_inside(xp,yp,zp)) { _draw_fill_push(xp,yp,zp); }
                      if (xn<width() && _draw_fill_is_inside(xn,yp,zp)) { _draw_fill_push(xn,yp,zp); }
                    }
                    if (yn<height() && !is_yn) {
                      if (_draw_fill_is_inside(x,yn,zp)) { _draw_fill_push(x,yn,zp); }
                      if (xp>=0 && _draw_fill_is_inside(xp,yn,zp)) { _draw_fill_push(xp,yn,zp); }
                      if (xn<width() && _draw_fill_is_inside(xn,yn,zp)) { _draw_fill_push(xn,yn,zp); }
                    }
                  }

                  if (zn<depth() && !is_zn) {
                    if (xp>=0 && _draw_fill_is_inside(xp,y,zn)) {
                      _draw_fill_push(xp,y,zn); if (step<0) is_zn = true;
                    }
                    if (xn<width() && _draw_fill_is_inside(xn,y,zn)) {
                      _draw_fill_push(xn,y,zn); if (step>0) is_zn = true;
                    }

                    if (yp>=0 && !is_yp) {
                      if (_draw_fill_is_inside(x,yp,zn)) { _draw_fill_push(x,yp,zn); }
                      if (xp>=0 && _draw_fill_is_inside(xp,yp,zn)) { _draw_fill_push(xp,yp,zn); }
                      if (xn<width() && _draw_fill_is_inside(xn,yp,zn)) { _draw_fill_push(xn,yp,zn); }
                    }
                    if (yn<height() && !is_yn) {
                      if (_draw_fill_is_inside(x,yn,zn)) { _draw_fill_push(x,yn,zn); }
                      if (xp>=0 && _draw_fill_is_inside(xp,yn,zn)) { _draw_fill_push(xp,yn,zn); }
                      if (xn<width() && _draw_fill_is_inside(xn,yn,zn)) { _draw_fill_push(xn,yn,zn); }
                    }
                  }
                }
              }
              x+=step;
            }
            if (step<0) { xl = ++x; x = xr + 1; is_yp = is_yn = is_zp = is_zn = false; }
            else xr = --x;
          }
          std::memset(_region.data(xl,y,z),1,xr - xl + 1);
          if (opacity==1) {
            if (sizeof(T)!=1) cimg_forC(*this,c) {
                const T val = (T)color[c];
                T *ptri = data(xl,y,z,c); for (int k = xl; k<=xr; ++k) *(ptri++) = val;
              }
            else {
              const int dx = xr - xl + 1;
              cimg_forC(*this,c) std::memset(data(xl,y,z,c),(int)color[c],dx);
            }
          } else cimg_forC(*this,c) {
              const T val = (T)(color[c]*nopacity);
              T *ptri = data(xl,y,z,c); for (int k = xl; k<=xr; ++k) { *ptri = (T)(val + *ptri*copacity); ++ptri; }
            }
        }
      }
      _region.move_to(region);
      return *this;
    }

    //! Draw a filled 3D region with the flood fill algorithm \overload.
    template<typename tc>
    CImg<T>& draw_fill(const int x0, const int y0, const int z0,
                       const tc *const color, const float opacity=1,
                       const float tolerance=0, const bool is_high_connectivity=false) {
      CImg<ucharT> tmp;
      return draw_fill(x0,y0,z0,color,opacity,tmp,tolerance,is_high_connectivity);
    }

    //! Draw a filled 2D region with the flood fill algorithm \overload.
    template<typename tc>
    CImg<T>& draw_fill(const int x0, const int y0,
                       const tc *const color, const float opacity=1,
                       const float tolerance=0, const bool is_high_connectivity=false) {
      CImg<ucharT> tmp;
      return draw_fill(x0,y0,0,color,opacity,tmp,tolerance,is_high_connectivity);
    }

    //! Draw a random plasma texture.
    /**
       \param alpha Alpha-parameter.
       \param beta Beta-parameter.
       \param scale Scale-parameter.
       \note Use the mid-point algorithm to render.
    **/
    CImg<T>& draw_plasma(const float alpha=1, const float beta=0, const unsigned int scale=8) {
      if (is_empty()) return *this;
      const int
        w0 = width(), h0 = height(),
        delta = 1<<std::min(scale,12U),
        w = cimg::round(w0,delta,1),
        h = cimg::round(h0,delta,1);
      cimg_uint64 rng = (cimg::_rand(),cimg::rng());
      CImg<T> canvas(w,h,depth(),spectrum());

      cimg_forZC(*this,z,c) {
        CImg<T> ref = canvas.get_shared_slice(z,c);

        // Init step.
        float r = alpha*delta + beta;
        for (int yt = 0; yt<h; yt+=delta)
          for (int xt = 0; xt<w; xt+=delta) {
            const Tfloat val = r*cimg::rand(-1,1,&rng);
            ref(xt,yt) = cimg::type<T>::cut(val);
          }

        for (int _delta = delta; _delta>1; _delta>>=1) {
          const int _delta2 = _delta>>1;
          r = alpha*_delta + beta;

          // Square step.
          for (int yt = _delta2; yt<h; yt+=_delta)
            for (int xt = _delta2; xt<w; xt+=_delta) {
              const int x0 = xt - _delta2, y0 = yt - _delta2, x1 = (xt + _delta2)%w, y1 = (yt + _delta2)%h;
              const Tfloat val = (Tfloat)(0.25f*(ref(x0,y0) + ref(x1,y0) + ref(x1,y1) + ref(x0,y1)) +
                                          r*cimg::rand(-1,1,&rng));
              ref(xt,yt) = cimg::type<T>::cut(val);
            }

          // Diamond steps.
          bool is_odd_y = false;
          for (int yt = 0; yt<h; yt+=_delta2) {
            for (int xt = is_odd_y?0:_delta2; xt<w; xt+=_delta) {
              const int
                x0 = cimg::mod(xt - _delta2,w), x1 = (xt + _delta2)%w,
                y0 = cimg::mod(yt - _delta2,h), y1 = (yt + _delta2)%h;
              const Tfloat val = (Tfloat)(0.25f*(ref(x0,yt) + ref(x1,yt) + ref(xt,y0) + ref(xt,y1)) +
                                          r*cimg::rand(-1,1,&rng));
              ref(xt,yt) = cimg::type<T>::cut(val);
            }
            is_odd_y = !is_odd_y;
          }
        }
      }
      cimg::srand(rng);
      return draw_image((w0 - w)/2,(h0 - h)/2,0,0,canvas);
    }

    //! Draw a quadratic Mandelbrot or Julia 2D fractal.
    /**
       \param x0 X-coordinate of the upper-left pixel.
       \param y0 Y-coordinate of the upper-left pixel.
       \param x1 X-coordinate of the lower-right pixel.
       \param y1 Y-coordinate of the lower-right pixel.
       \param colormap Colormap.
       \param opacity Drawing opacity.
       \param z0r Real part of the upper-left fractal vertex.
       \param z0i Imaginary part of the upper-left fractal vertex.
       \param z1r Real part of the lower-right fractal vertex.
       \param z1i Imaginary part of the lower-right fractal vertex.
       \param iteration_max Maximum number of iterations for each estimated point.
       \param is_normalized_iteration Indicates whether iterations are normalized.
       \param is_julia_set Indicates whether the Mandelbrot or Julia set is rendered.
       \param param_r Real part of the Julia set parameter.
       \param param_i Imaginary part of the Julia set parameter.
       \note Fractal rendering is done by the Escape Time Algorithm.
    **/
    template<typename tc>
    CImg<T>& draw_mandelbrot(const int x0, const int y0, const int x1, const int y1,
                             const CImg<tc>& colormap, const float opacity=1,
                             const double z0r=-2, const double z0i=-2, const double z1r=2, const double z1i=2,
                             const unsigned int iteration_max=255,
                             const bool is_normalized_iteration=false,
                             const bool is_julia_set=false,
                             const double param_r=0, const double param_i=0) {
      if (is_empty()) return *this;
      CImg<tc> palette;
      if (colormap) palette.assign(colormap._data,colormap.size()/colormap._spectrum,1,1,colormap._spectrum,true);
      if (palette && palette._spectrum!=_spectrum)
        throw CImgArgumentException(_cimg_instance
                                    "draw_mandelbrot(): Instance and specified colormap (%u,%u,%u,%u,%p) have "
                                    "incompatible dimensions.",
                                    cimg_instance,
                                    colormap._width,colormap._height,colormap._depth,colormap._spectrum,colormap._data);

      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f), ln2 = (float)std::log(2.);
      const int
        _x0 = cimg::cut(x0,0,width() - 1),
        _y0 = cimg::cut(y0,0,height() - 1),
        _x1 = cimg::cut(x1,0,width() - 1),
        _y1 = cimg::cut(y1,0,height() - 1);

      cimg_pragma_openmp(parallel for cimg_openmp_collapse(2)
                         cimg_openmp_if((1 + _x1 - _x0)*(1 + _y1 - _y0)>=(cimg_openmp_sizefactor)*2048))
      for (int q = _y0; q<=_y1; ++q)
        for (int p = _x0; p<=_x1; ++p) {
          unsigned int iteration = 0;
          const double x = z0r + p*(z1r-z0r)/_width, y = z0i + q*(z1i-z0i)/_height;
          double zr, zi, cr, ci;
          if (is_julia_set) { zr = x; zi = y; cr = param_r; ci = param_i; }
          else { zr = param_r; zi = param_i; cr = x; ci = y; }
          for (iteration=1; zr*zr + zi*zi<=4 && iteration<=iteration_max; ++iteration) {
            const double temp = zr*zr - zi*zi + cr;
            zi = 2*zr*zi + ci;
            zr = temp;
          }
          if (iteration>iteration_max) {
            if (palette) {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)palette(0,c);
              else cimg_forC(*this,c) (*this)(p,q,0,c) = (T)(palette(0,c)*nopacity + (*this)(p,q,0,c)*copacity);
            } else {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)0;
              else cimg_forC(*this,c) (*this)(p,q,0,c) = (T)((*this)(p,q,0,c)*copacity);
            }
          } else if (is_normalized_iteration) {
            const float
              normz = (float)cimg::abs(zr*zr + zi*zi),
              niteration = (float)(iteration + 1 - std::log(std::log(normz))/ln2);
            if (palette) {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)palette._linear_atX(niteration,c);
              else cimg_forC(*this,c)
                     (*this)(p,q,0,c) = (T)(palette._linear_atX(niteration,c)*nopacity + (*this)(p,q,0,c)*copacity);
            } else {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)niteration;
              else cimg_forC(*this,c) (*this)(p,q,0,c) = (T)(niteration*nopacity + (*this)(p,q,0,c)*copacity);
            }
          } else {
            if (palette) {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)palette._atX(iteration,c);
              else cimg_forC(*this,c) (*this)(p,q,0,c) = (T)(palette(iteration,c)*nopacity + (*this)(p,q,0,c)*copacity);
            } else {
              if (opacity>=1) cimg_forC(*this,c) (*this)(p,q,0,c) = (T)iteration;
              else cimg_forC(*this,c) (*this)(p,q,0,c) = (T)(iteration*nopacity + (*this)(p,q,0,c)*copacity);
            }
          }
        }
      return *this;
    }

    //! Draw a quadratic Mandelbrot or Julia 2D fractal \overload.
    template<typename tc>
    CImg<T>& draw_mandelbrot(const CImg<tc>& colormap, const float opacity=1,
                             const double z0r=-2, const double z0i=-2, const double z1r=2, const double z1i=2,
                             const unsigned int iteration_max=255,
                             const bool is_normalized_iteration=false,
                             const bool is_julia_set=false,
                             const double param_r=0, const double param_i=0) {
      return draw_mandelbrot(0,0,_width - 1,_height - 1,colormap,opacity,
                             z0r,z0i,z1r,z1i,iteration_max,is_normalized_iteration,is_julia_set,param_r,param_i);
    }

    //! Draw a 1D gaussian function.
    /**
       \param xc X-coordinate of the gaussian center.
       \param sigma Standard variation of the gaussian distribution.
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename tc>
    CImg<T>& draw_gaussian(const float xc, const float sigma,
                           const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_gaussian(): Specified color is (null).",
                                    cimg_instance);
      const float sigma2 = 2*sigma*sigma, nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      const ulongT whd = (ulongT)_width*_height*_depth;
      const tc *col = color;
      cimg_forX(*this,x) {
        const float dx = (x - xc), val = (float)std::exp(-dx*dx/sigma2);
        T *ptrd = data(x,0,0,0);
        if (opacity>=1) cimg_forC(*this,c) { *ptrd = (T)(val*(*col++)); ptrd+=whd; }
        else cimg_forC(*this,c) { *ptrd = (T)(nopacity*val*(*col++) + *ptrd*copacity); ptrd+=whd; }
        col-=_spectrum;
      }
      return *this;
    }

    //! Draw a 2D gaussian function.
    /**
       \param xc X-coordinate of the gaussian center.
       \param yc Y-coordinate of the gaussian center.
       \param tensor Covariance matrix (must be 2x2).
       \param color Pointer to \c spectrum() consecutive values, defining the drawing color.
       \param opacity Drawing opacity.
    **/
    template<typename t, typename tc>
    CImg<T>& draw_gaussian(const float xc, const float yc, const CImg<t>& tensor,
                           const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      if (tensor._width!=2 || tensor._height!=2 || tensor._depth!=1 || tensor._spectrum!=1)
        throw CImgArgumentException(_cimg_instance
                                    "draw_gaussian(): Specified tensor (%u,%u,%u,%u,%p) is not a 2x2 matrix.",
                                    cimg_instance,
                                    tensor._width,tensor._height,tensor._depth,tensor._spectrum,tensor._data);
      if (!color)
        throw CImgArgumentException(_cimg_instance
                                    "draw_gaussian(): Specified color is (null).",
                                    cimg_instance);
      typedef typename CImg<t>::Tfloat tfloat;
      const CImg<tfloat> invT = tensor.get_invert(), invT2 = (invT*invT)/=-2.;
      const tfloat a = invT2(0,0), b = 2*invT2(1,0), c = invT2(1,1);
      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      const ulongT whd = (ulongT)_width*_height*_depth;
      const tc *col = color;
      float dy = -yc;
      cimg_forY(*this,y) {
        float dx = -xc;
        cimg_forX(*this,x) {
          const float val = (float)std::exp(a*dx*dx + b*dx*dy + c*dy*dy);
          T *ptrd = data(x,y,0,0);
          if (opacity>=1) cimg_forC(*this,k) { *ptrd = (T)(val*(*col++)); ptrd+=whd; }
          else cimg_forC(*this,k) { *ptrd = (T)(nopacity*val*(*col++) + *ptrd*copacity); ptrd+=whd; }
          col-=_spectrum;
          ++dx;
        }
        ++dy;
      }
      return *this;
    }

    //! Draw a 2D gaussian function \overload.
    template<typename tc>
    CImg<T>& draw_gaussian(const int xc, const int yc, const float r1, const float r2, const float ru, const float rv,
                           const tc *const color, const float opacity=1) {
      const double
        a = r1*ru*ru + r2*rv*rv,
        b = (r1-r2)*ru*rv,
        c = r1*rv*rv + r2*ru*ru;
      const CImg<Tfloat> tensor(2,2,1,1, a,b,b,c);
      return draw_gaussian(xc,yc,tensor,color,opacity);
    }

    //! Draw a 2D gaussian function \overload.
    template<typename tc>
    CImg<T>& draw_gaussian(const float xc, const float yc, const float sigma,
                           const tc *const color, const float opacity=1) {
      return draw_gaussian(xc,yc,CImg<floatT>::diagonal(sigma,sigma),color,opacity);
    }

    //! Draw a 3D gaussian function \overload.
    template<typename t, typename tc>
    CImg<T>& draw_gaussian(const float xc, const float yc, const float zc, const CImg<t>& tensor,
                           const tc *const color, const float opacity=1) {
      if (is_empty()) return *this;
      typedef typename CImg<t>::Tfloat tfloat;
      if (tensor._width!=3 || tensor._height!=3 || tensor._depth!=1 || tensor._spectrum!=1)
        throw CImgArgumentException(_cimg_instance
                                    "draw_gaussian(): Specified tensor (%u,%u,%u,%u,%p) is not a 3x3 matrix.",
                                    cimg_instance,
                                    tensor._width,tensor._height,tensor._depth,tensor._spectrum,tensor._data);

      const CImg<tfloat> invT = tensor.get_invert(), invT2 = (invT*invT)/=-2.;
      const tfloat a = invT2(0,0), b = 2*invT2(1,0), c = 2*invT2(2,0), d = invT2(1,1), e = 2*invT2(2,1), f = invT2(2,2);
      const float nopacity = cimg::abs(opacity), copacity = 1 - std::max(opacity,0.f);
      const ulongT whd = (ulongT)_width*_height*_depth;
      const tc *col = color;
      cimg_forXYZ(*this,x,y,z) {
        const float
          dx = (x - xc), dy = (y - yc), dz = (z - zc),
          val = (float)std::exp(a*dx*dx + b*dx*dy + c*dx*dz + d*dy*dy + e*dy*dz + f*dz*dz);
        T *ptrd = data(x,y,z,0);
        if (opacity>=1) cimg_forC(*this,k) { *ptrd = (T)(val*(*col++)); ptrd+=whd; }
        else cimg_forC(*this,k) { *ptrd = (T)(nopacity*val*(*col++) + *ptrd*copacity); ptrd+=whd; }
        col-=_spectrum;
      }
      return *this;
    }

    //! Draw a 3D gaussian function \overload.
    template<typename tc>
    CImg<T>& draw_gaussian(const float xc, const float yc, const float zc, const float sigma,
                           const tc *const color, const float opacity=1) {
      return draw_gaussian(xc,yc,zc,CImg<floatT>::diagonal(sigma,sigma,sigma),color,opacity);
    }

    //! Draw a 3D object.
    /**
       \param x0 X-coordinate of the 3D object position
       \param y0 Y-coordinate of the 3D object position
       \param z0 Z-coordinate of the 3D object position
       \param vertices Image Nx3 describing 3D point coordinates
       \param primitives List of P primitives
       \param colors List of P color (or textures)
       \param opacities Image or list of P opacities
       \param render_type Render type (0=Points, 1=Lines, 2=Faces (no light), 3=Faces (flat), 4=Faces(Gouraud)
       \param is_double_sided Indicates whether object faces have two sides or are oriented.
       \param focal Focal length (0 for parallel projection).
       \param lightx X-coordinate of the light
       \param lighty Y-coordinate of the light
       \param lightz Z-coordinate of the light
       \param specular_lightness Amount of specular light.
       \param specular_shininess Shininess of the object
       \param g_opacity Global opacity of the object.
       \param is_multithreaded_rendering Indicates whether mesh rendering is done with multiple threads
    **/
    template<typename tp, typename tf, typename tc, typename to>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors, const CImg<to>& opacities,
                           const unsigned int render_type=4,
                           const bool is_double_sided=false, const float focal=700,
                           const float lightx=0, const float lighty=0, const float lightz=-5e8,
                           const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                           const float g_opacity=1, const bool is_multithreaded_rendering=false) {
      return draw_object3d(x0,y0,z0,vertices,primitives,colors,opacities,render_type,
                           is_double_sided,focal,lightx,lighty,lightz,
                           specular_lightness,specular_shininess,g_opacity,CImg<floatT>::empty(),
                           is_multithreaded_rendering);
    }

    //! Draw a 3D object \overload.
    template<typename tp, typename tf, typename tc, typename to, typename tz>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors, const CImg<to>& opacities,
                           const unsigned int render_type,
                           const bool is_double_sided, const float focal,
                           const float lightx, const float lighty, const float lightz,
                           const float specular_lightness, const float specular_shininess,
                           const float g_opacity, CImg<tz>& zbuffer,
                           const bool is_multithreaded_rendering=false) {
      return _draw_object3d(zbuffer,x0,y0,z0,vertices,primitives,colors,opacities,
                            render_type,is_double_sided,focal,lightx,lighty,lightz,
                            specular_lightness,specular_shininess,g_opacity,1,
                            is_multithreaded_rendering);
    }

    //! Draw a 3D object \overload.
    template<typename tp, typename tf, typename tc, typename to>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors, const CImgList<to>& opacities,
                           const unsigned int render_type=4,
                           const bool is_double_sided=false, const float focal=700,
                           const float lightx=0, const float lighty=0, const float lightz=-5e8,
                           const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                           const float g_opacity=1, const bool is_multithreaded_rendering=false) {
      return draw_object3d(x0,y0,z0,vertices,primitives,colors,opacities,render_type,
                           is_double_sided,focal,lightx,lighty,lightz,
                           specular_lightness,specular_shininess,g_opacity,CImg<floatT>::empty(),
                           is_multithreaded_rendering);
    }

    //! Draw a 3D object \overload.
    template<typename tp, typename tf, typename tc, typename to, typename tz>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors, const CImgList<to>& opacities,
                           const unsigned int render_type,
                           const bool is_double_sided, const float focal,
                           const float lightx, const float lighty, const float lightz,
                           const float specular_lightness, const float specular_shininess,
                           const float g_opacity, CImg<tz>& zbuffer,
                           const bool is_multithreaded_rendering=false) {
      return _draw_object3d(zbuffer,x0,y0,z0,vertices,primitives,colors,opacities,
                            render_type,is_double_sided,focal,lightx,lighty,lightz,
                            specular_lightness,specular_shininess,g_opacity,1,
                            is_multithreaded_rendering);
    }

    //! Draw a 3D object \overload.
    template<typename tp, typename tf, typename tc>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors,
                           const unsigned int render_type=4,
                           const bool is_double_sided=false, const float focal=700,
                           const float lightx=0, const float lighty=0, const float lightz=-5e8,
                           const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                           const float g_opacity=1, const bool is_multithreaded_rendering=false) {
      return draw_object3d(x0,y0,z0,vertices,primitives,colors,CImg<floatT>::const_empty(),
                           render_type,is_double_sided,focal,lightx,lighty,lightz,
                           specular_lightness,specular_shininess,g_opacity,CImg<floatT>::empty(),
                           is_multithreaded_rendering);
    }

    //! Draw a 3D object \overload.
    template<typename tp, typename tf, typename tc, typename tz>
    CImg<T>& draw_object3d(const float x0, const float y0, const float z0,
                           const CImg<tp>& vertices, const CImgList<tf>& primitives,
                           const CImgList<tc>& colors,
                           const unsigned int render_type,
                           const bool is_double_sided, const float focal,
                           const float lightx, const float lighty, const float lightz,
                           const float specular_lightness, const float specular_shininess,
                           const float g_opacity, CImg<tz>& zbuffer,
                           const bool is_multithreaded_rendering=false) {
      return draw_object3d(x0,y0,z0,vertices,primitives,colors,CImg<floatT>::const_empty(),
                           render_type,is_double_sided,focal,lightx,lighty,lightz,
                           specular_lightness,specular_shininess,g_opacity,zbuffer,
                           is_multithreaded_rendering);
    }

    template<typename t, typename to>
    static float __draw_object3d(const CImgList<t>& opacities, const unsigned int n_primitive, CImg<to>& opacity) {
      if (n_primitive>=opacities._width || opacities[n_primitive].is_empty()) { opacity.assign(); return 1; }
      if (opacities[n_primitive].size()==1) { opacity.assign(); return opacities(n_primitive,0); }
      opacity.assign(opacities[n_primitive],true);
      return 1.f;
    }

    template<typename t, typename to>
    static float __draw_object3d(const CImg<t>& opacities, const unsigned int n_primitive, CImg<to>& opacity) {
      opacity.assign();
      return n_primitive>=opacities._width?1.f:(float)opacities[n_primitive];
    }

    template<typename t>
    static float ___draw_object3d(const CImgList<t>& opacities, const unsigned int n_primitive) {
      return n_primitive<opacities._width && opacities[n_primitive].size()==1?(float)opacities(n_primitive,0):1.f;
    }

    template<typename t>
    static float ___draw_object3d(const CImg<t>& opacities, const unsigned int n_primitive) {
      return n_primitive<opacities._width?(float)opacities[n_primitive]:1.f;
    }

    // Draw flat-colored segment (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_flat_colored_segment(CImg<tz>& zbuffer,
                                                 const float X, const float Y, const float Z,
                                                 int n0, int n1,
                                                 const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                 const tc *const color, const float opacity,
                                                 float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal;
      if (z0>z1) cimg::swap(n0,n1,z0,z1);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z1<zc) return *this; // Two vertices behind camera
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fact = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact*(fx1 - fx0), nfy0 = fy0 + fact*(fy1 - fy0);
        z0 = zc;
        x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
      }
      if (zbuffer) draw_line(zbuffer,x0,y0,z0,x1,y1,z1,color,opacity);
      else draw_line(x0,y0,x1,y1,color,opacity);
      return *this;
    }

    // Draw flat-textured segment (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_flat_textured_segment(CImg<tz>& zbuffer,
                                                  const float X, const float Y, const float Z,
                                                  int n0, int n1,
                                                  const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                  const CImg<tc>& texture,
                                                  int tx0, int ty0,
                                                  int tx1, int ty1,
                                                  const float opacity,
                                                  float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal;
      if (focal && z0>z1) cimg::swap(n0,n1,z0,z1,tx0,tx1,ty0,ty1);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1));
      const float zc = 1; // Clipping plane
      if (z0<zc) {
        if (z1<zc) return *this; // Two vertices behind camera
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fact = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact*(fx1 - fx0), nfy0 = fy0 + fact*(fy1 - fy0);
        if (!focal) focal = zc;
        z0 = zc;
        x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
        tx0 = cimg::uiround(tx0 + fact*(tx1 - tx0)); ty0 = cimg::uiround(ty0 + fact*(ty1 - ty0));
      }
      if (zbuffer) draw_line(zbuffer,x0,y0,z0,x1,y1,z1,texture,tx0,ty0,tx1,ty1,opacity);
      else draw_line(x0,y0,z0,x1,y1,z1,texture,tx0,ty0,tx1,ty1,opacity);
      return *this;
    }

    // Draw flat-colored triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_flat_colored_triangle(CImg<tz>& zbuffer,
                                                  const float X, const float Y, const float Z,
                                                  int n0, int n1, int n2,
                                                  const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                  const tc *const color, const float opacity,
                                                  const float brightness, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1);
          if (brightness==1) {
            if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,color,opacity).
                           draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,color,opacity);
            else draw_triangle(nx0,ny0,x1,y1,x2,y2,color,opacity).
                   draw_triangle(nx0,ny0,nx1,ny1,x2,y2,color,opacity);
          } else {
            if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,color,opacity,brightness).
                           draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,color,opacity,brightness);
            else _draw_triangle(nx0,ny0,x1,y1,x2,y2,color,opacity,brightness).
                   _draw_triangle(nx0,ny0,nx1,ny1,x2,y2,color,opacity,brightness);
          }
          return *this;
        }
      }
      if (brightness==1) {
        if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,color,opacity);
        else draw_triangle(x0,y0,x1,y1,x2,y2,color,opacity);
      } else {
        if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,color,opacity,brightness);
        else _draw_triangle(x0,y0,x1,y1,x2,y2,color,opacity,brightness);
      }
      return *this;
    }

    // Draw flat-textured triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_flat_textured_triangle(CImg<tz>& zbuffer,
                                                   const float X, const float Y, const float Z,
                                                   int n0, int n1, int n2,
                                                   const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                   const CImg<tc>& texture,
                                                   int tx0, int ty0,
                                                   int tx1, int ty1,
                                                   int tx2, int ty2,
                                                   const float opacity,
                                                   const float brightness, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2,tx0,tx2,ty0,ty2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1,tx0,tx1,ty0,ty1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2,tx1,tx2,ty1,ty2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
          tx0 = cimg::uiround(tx0 + fact0*(tx2 - tx0)); ty0 = cimg::uiround(ty0 + fact0*(ty2 - ty0));
          tx1 = cimg::uiround(tx1 + fact1*(tx2 - tx1)); ty1 = cimg::uiround(ty1 + fact1*(ty2 - ty1));
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1),
            ntx0 = cimg::uiround(tx0 + fact0*(tx1 - tx0)), nty0 = cimg::uiround(ty0 + fact0*(ty1 - ty0)),
            ntx1 = cimg::uiround(tx0 + fact1*(tx2 - tx0)), nty1 = cimg::uiround(ty0 + fact1*(ty2 - ty0));
          if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                                     texture,ntx0,nty0,tx1,ty1,tx2,ty2,opacity,brightness).
                         draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                                       texture,ntx0,nty0,ntx1,nty1,tx2,ty2,opacity,brightness);
          else draw_triangle(nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                             texture,ntx0,nty0,tx1,ty1,tx2,ty2,opacity,brightness).
                 draw_triangle(nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                               texture,ntx0,nty0,ntx1,nty1,tx2,ty2,opacity,brightness);
          return *this;
        }
      }
      if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,
                                 texture,tx0,ty0,tx1,ty1,tx2,ty2,opacity,brightness);
      else draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,
                         texture,tx0,ty0,tx1,ty1,tx2,ty2,opacity,brightness);
      return *this;
    }

    // Draw gouraud-colored triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_gouraud_colored_triangle(CImg<tz>& zbuffer,
                                                     const float X, const float Y, const float Z,
                                                     int n0, int n1, int n2,
                                                     const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                     const tc *const color,
                                                     float bs0, float bs1, float bs2,
                                                     const float opacity, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2,bs0,bs2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1,bs0,bs1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2,bs1,bs2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
          bs0 = bs0 + fact0*(bs2 - bs0);
          bs1 = bs1 + fact1*(bs2 - bs1);
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nbs0 = bs0 + fact0*(bs1 - bs0),
            nbs1 = bs0 + fact1*(bs2 - bs0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1);
          if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,color,nbs0,bs1,bs2,opacity).
                         draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,color,nbs0,nbs1,bs2,opacity);
          else draw_triangle(nx0,ny0,x1,y1,x2,y2,color,nbs0,bs1,bs2,opacity).
                 draw_triangle(nx0,ny0,nx1,ny1,x2,y2,color,nbs0,nbs1,bs2,opacity);


          return *this;
        }
      }
      if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,color,bs0,bs1,bs2,opacity);
      else draw_triangle(x0,y0,x1,y1,x2,y2,color,bs0,bs1,bs2,opacity);
      return *this;
    }

    // Draw gouraud-textured triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_gouraud_textured_triangle(CImg<tz>& zbuffer,
                                                      const float X, const float Y, const float Z,
                                                      int n0, int n1, int n2,
                                                      const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                      const CImg<tc>& texture,
                                                      int tx0, int ty0,
                                                      int tx1, int ty1,
                                                      int tx2, int ty2,
                                                      float bs0, float bs1, float bs2,
                                                      const float opacity, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2,tx0,tx2,ty0,ty2,bs0,bs2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1,tx0,tx1,ty0,ty1,bs0,bs1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2,tx1,tx2,ty1,ty2,bs1,bs2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
          tx0 = cimg::uiround(tx0 + fact0*(tx2 - tx0)); ty0 = cimg::uiround(ty0 + fact0*(ty2 - ty0));
          tx1 = cimg::uiround(tx1 + fact1*(tx2 - tx1)); ty1 = cimg::uiround(ty1 + fact1*(ty2 - ty1));
          bs0 = bs0 + fact0*(bs2 - bs0);
          bs1 = bs1 + fact1*(bs2 - bs1);
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nbs0 = bs0 + fact0*(bs1 - bs0),
            nbs1 = bs0 + fact1*(bs2 - bs0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1),
            ntx0 = cimg::uiround(tx0 + fact0*(tx1 - tx0)), nty0 = cimg::uiround(ty0 + fact0*(ty1 - ty0)),
            ntx1 = cimg::uiround(tx0 + fact1*(tx2 - tx0)), nty1 = cimg::uiround(ty0 + fact1*(ty2 - ty0));
          if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                                     texture,ntx0,nty0,tx1,ty1,tx2,ty2,nbs0,bs1,bs2,opacity).
                         draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                                       texture,ntx0,nty0,ntx1,nty1,tx2,ty2,nbs0,nbs1,bs2,opacity);
          else draw_triangle(nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                             texture,ntx0,nty0,tx1,ty1,tx2,ty2,nbs0,bs1,bs2,opacity).
                 draw_triangle(nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                               texture,ntx0,nty0,ntx1,nty1,tx2,ty2,nbs0,nbs1,bs2,opacity);
          return *this;
        }
      }
      if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,texture,tx0,ty0,tx1,ty1,tx2,ty2,
                                 bs0,bs1,bs2,opacity);
      else draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,texture,tx0,ty0,tx1,ty1,tx2,ty2,bs0,bs1,bs2,opacity);
      return *this;
    }

    // Draw phong-colored triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_phong_colored_triangle(CImg<tz>& zbuffer,
                                                   const float X, const float Y, const float Z,
                                                   int n0, int n1, int n2,
                                                   const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                   const tc *const color,
                                                   const CImg<floatT>& light_texture,
                                                   int lx0, int ly0,
                                                   int lx1, int ly1,
                                                   int lx2, int ly2,
                                                   const float opacity, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2,lx0,lx2,ly0,ly2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1,lx0,lx1,ly0,ly1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2,lx1,lx2,ly1,ly2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
          lx0 = cimg::uiround(lx0 + fact0*(lx2 - lx0)); ly0 = cimg::uiround(ly0 + fact0*(ly2 - ly0));
          lx1 = cimg::uiround(lx1 + fact1*(lx2 - lx1)); ly1 = cimg::uiround(ly1 + fact1*(ly2 - ly1));
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1),
            nlx0 = cimg::uiround(lx0 + fact0*(lx1 - lx0)), nly0 = cimg::uiround(ly0 + fact0*(ly1 - ly0)),
            nlx1 = cimg::uiround(lx0 + fact1*(lx2 - lx0)), nly1 = cimg::uiround(ly0 + fact1*(ly2 - ly0));
          if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,color,
                                     light_texture,nlx0,nly0,lx1,ly1,lx2,ly2,opacity).
                         draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,color,
                                       light_texture,nlx0,nly0,nlx1,nly1,lx2,ly2,opacity);
          else draw_triangle(nx0,ny0,x1,y1,x2,y2,color,
                             light_texture,nlx0,nly0,lx1,ly1,lx2,ly2,opacity).
                 draw_triangle(nx0,ny0,nx1,ny1,x2,y2,color,
                               light_texture,nlx0,nly0,nlx1,nly1,lx2,ly2,opacity);
          return *this;
        }
      }
      if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,color,
                                 light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      else draw_triangle(x0,y0,x1,y1,x2,y2,color,
                         light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      return *this;
    }

    // Draw phong-textured triangle (with z-plane clipping).
    template<typename tz, typename tp, typename tc>
    CImg<T>& _draw_object3d_phong_textured_triangle(CImg<tz>& zbuffer,
                                                    const float X, const float Y, const float Z,
                                                    int n0, int n1, int n2,
                                                    const CImg<tp>& vertices, const CImg<floatT>& projections,
                                                    const CImg<tc>& texture,
                                                    int tx0, int ty0, int tx1, int ty1, int tx2, int ty2,
                                                    const CImg<floatT>& light_texture,
                                                    int lx0, int ly0, int lx1, int ly1, int lx2, int ly2,
                                                    const float opacity, float focal) {
      float z0 = vertices(n0,2) + Z + focal, z1 = vertices(n1,2) + Z + focal, z2 = vertices(n2,2) + Z + focal;
      if (z0>z2) cimg::swap(n0,n2,z0,z2,tx0,tx2,ty0,ty2,lx0,lx2,ly0,ly2);
      if (z0>z1) cimg::swap(n0,n1,z0,z1,tx0,tx1,ty0,ty1,lx0,lx1,ly0,ly1);
      if (z1>z2) cimg::swap(n1,n2,z1,z2,tx1,tx2,ty1,ty2,lx1,lx2,ly1,ly2);
      int
        x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
        x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
        x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
      const float zc = 1; // Clipping plane
      if (focal && z0<zc) {
        if (z2<zc) return *this;
        const float
          fx0 = vertices(n0,0), fy0 = vertices(n0,1),
          fx1 = vertices(n1,0), fy1 = vertices(n1,1),
          fx2 = vertices(n2,0), fy2 = vertices(n2,1);
        if (z1<zc) { // Two vertices behind camera
          const float
            fact0 = (zc - z0)/(z2 - z0), nfx0 = fx0 + fact0*(fx2 - fx0), nfy0 = fy0 + fact0*(fy2 - fy0),
            fact1 = (zc - z1)/(z2 - z1), nfx1 = fx1 + fact1*(fx2 - fx1), nfy1 = fy1 + fact1*(fy2 - fy1);
          z0 = z1 = zc;
          x0 = cimg::uiround(X + focal*nfx0/z0); y0 = cimg::uiround(Y + focal*nfy0/z0);
          x1 = cimg::uiround(X + focal*nfx1/z1); y1 = cimg::uiround(Y + focal*nfy1/z1);
          tx0 = cimg::uiround(tx0 + fact0*(tx2 - tx0)); ty0 = cimg::uiround(ty0 + fact0*(ty2 - ty0));
          tx1 = cimg::uiround(tx1 + fact1*(tx2 - tx1)); ty1 = cimg::uiround(ty1 + fact1*(ty2 - ty1));
          lx0 = cimg::uiround(lx0 + fact0*(lx2 - lx0)); ly0 = cimg::uiround(ly0 + fact0*(ly2 - ly0));
          lx1 = cimg::uiround(lx1 + fact1*(lx2 - lx1)); ly1 = cimg::uiround(ly1 + fact1*(ly2 - ly1));
        } else { // One vertex behind camera
          const float
            fact0 = (zc - z0)/(z1 - z0), nfx0 = fx0 + fact0*(fx1 - fx0), nfy0 = fy0 + fact0*(fy1 - fy0),
            fact1 = (zc - z0)/(z2 - z0), nfx1 = fx0 + fact1*(fx2 - fx0), nfy1 = fy0 + fact1*(fy2 - fy0),
            nz0 = zc, nz1 = zc;
          const int
            nx0 = cimg::uiround(X + focal*nfx0/nz0), ny0 = cimg::uiround(Y + focal*nfy0/nz0),
            nx1 = cimg::uiround(X + focal*nfx1/nz1), ny1 = cimg::uiround(Y + focal*nfy1/nz1),
            ntx0 = cimg::uiround(tx0 + fact0*(tx1 - tx0)), nty0 = cimg::uiround(ty0 + fact0*(ty1 - ty0)),
            ntx1 = cimg::uiround(tx0 + fact1*(tx2 - tx0)), nty1 = cimg::uiround(ty0 + fact1*(ty2 - ty0)),
            nlx0 = cimg::uiround(lx0 + fact0*(lx1 - lx0)), nly0 = cimg::uiround(ly0 + fact0*(ly1 - ly0)),
            nlx1 = cimg::uiround(lx0 + fact1*(lx2 - lx0)), nly1 = cimg::uiround(ly0 + fact1*(ly2 - ly0));
          if (zbuffer) draw_triangle(zbuffer,nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                                     texture,ntx0,nty0,tx1,ty1,tx2,ty2,
                                     light_texture,nlx0,nly0,lx1,ly1,lx2,ly2,opacity).
                         draw_triangle(zbuffer,nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                                       texture,ntx0,nty0,ntx1,nty1,tx2,ty2,
                                       light_texture,nlx0,nly0,nlx1,nly1,lx2,ly2,opacity);
          else draw_triangle(nx0,ny0,nz0,x1,y1,z1,x2,y2,z2,
                             texture,ntx0,nty0,tx1,ty1,tx2,ty2,
                             light_texture,nlx0,nly0,lx1,ly1,lx2,ly2,opacity).
                 draw_triangle(nx0,ny0,nz0,nx1,ny1,nz1,x2,y2,z2,
                               texture,ntx0,nty0,ntx1,nty1,tx2,ty2,
                               light_texture,nlx0,nly0,nlx1,nly1,lx2,ly2,opacity);
          return *this;
        }
      }
      if (zbuffer) draw_triangle(zbuffer,x0,y0,z0,x1,y1,z1,x2,y2,z2,
                                 texture,tx0,ty0,tx1,ty1,tx2,ty2,
                                 light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      else draw_triangle(x0,y0,z0,x1,y1,z1,x2,y2,z2,
                         texture,tx0,ty0,tx1,ty1,tx2,ty2,
                         light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity);
      return *this;
    }

    template<typename tz, typename tp, typename tf, typename tc, typename to>
    CImg<T>& _draw_object3d(CImg<tz>& zbuffer,
                            const float X, const float Y, const float Z,
                            const CImg<tp>& vertices,
                            const CImgList<tf>& primitives,
                            const CImgList<tc>& colors,
                            const to& opacities,
                            const unsigned int render_type,
                            const bool is_double_sided, const float focal,
                            const float lightx, const float lighty, const float lightz,
                            const float specular_lightness, const float specular_shininess,
                            const float g_opacity, const float sprite_scale,
                            const bool is_multithreaded_rendering) {
      typedef typename to::value_type _to;
      cimg::unused(is_multithreaded_rendering);
      if (is_empty() || !vertices || !primitives) return *this;
      CImg<char> error_message(1024);
      if (!vertices.is_object3d(primitives,colors,opacities,false,error_message))
        throw CImgArgumentException(_cimg_instance
                                    "draw_object3d(): Invalid specified 3D object (%u,%u) (%s).",
                                    cimg_instance,vertices._width,primitives._width,error_message.data());
      if (render_type==5) cimg::mutex(10); // Static variable used in this case, breaks thread-safety

      const float
        _focal = focal?cimg::abs(focal):1e8f, // Parallel projection -> very large focal length
        nspec = 1 - cimg::cut(specular_shininess,0.0f,1.0f),
        nspec2 = 1 + std::max(specular_lightness,0.0f),
        nsl1 = (nspec2 - 1)/cimg::sqr(nspec - 1),
        nsl2 = 1 - 2*nsl1*nspec,
        nsl3 = nspec2 - nsl1 - nsl2;

      // Create light texture for phong-like rendering.
      CImg<floatT> light_texture;
      if (render_type==5) {
        if (colors._width>primitives._width) {
          static CImg<floatT> default_light_texture;
          static const tc *lptr = 0;
          static tc ref_values[64] = {};
          const CImg<tc>& img = colors.back();
          bool is_same_texture = (lptr==img._data);
          if (is_same_texture)
            for (unsigned int r = 0, j = 0; j<8; ++j)
              for (unsigned int i = 0; i<8; ++i)
                if (ref_values[r++]!=img(i*img._width/9,j*img._height/9,0,(i + j)%img._spectrum)) {
                  is_same_texture = false; break;
                }
          if (!is_same_texture || default_light_texture._spectrum<_spectrum) {
            (default_light_texture.assign(img,false)/=255).resize(-100,-100,1,_spectrum);
            lptr = colors.back().data();
            for (unsigned int r = 0, j = 0; j<8; ++j)
              for (unsigned int i = 0; i<8; ++i)
                ref_values[r++] = img(i*img._width/9,j*img._height/9,0,(i + j)%img._spectrum);
          }
          light_texture.assign(default_light_texture,true);
        } else {
          static CImg<floatT> default_light_texture;
          static float olightx = 0, olighty = 0, olightz = 0, ospecular_shininess = 0;
          if (!default_light_texture ||
              lightx!=olightx || lighty!=olighty || lightz!=olightz ||
              specular_shininess!=ospecular_shininess || default_light_texture._spectrum<_spectrum) {
            default_light_texture.assign(512,512);
            const float
              dlx = lightx - X,
              dly = lighty - Y,
              dlz = lightz - Z,
              nl = cimg::hypot(dlx,dly,dlz),
              nlx = (default_light_texture._width - 1)/2*(1 + dlx/nl),
              nly = (default_light_texture._height - 1)/2*(1 + dly/nl),
              white[] = { 1 };
            default_light_texture.draw_gaussian(nlx,nly,default_light_texture._width/3.0f,white);
            cimg_forXY(default_light_texture,x,y) {
              const float factor = default_light_texture(x,y);
              if (factor>nspec) default_light_texture(x,y) = std::min(2.f,nsl1*factor*factor + nsl2*factor + nsl3);
            }
            default_light_texture.resize(-100,-100,1,_spectrum);
            olightx = lightx; olighty = lighty; olightz = lightz; ospecular_shininess = specular_shininess;
          }
          light_texture.assign(default_light_texture,true);
        }
      }

      // Compute normal 3D vectors.
      CImg<floatT> p_centers, p_normals, v_normals;
      if (render_type>=2) {

        // 3D normals to primitives.
        p_centers.assign(primitives._width,3);
        p_normals.assign(primitives._width,3);
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                       primitives.size()>=cimg_openmp_sizefactor*4096))
        cimglist_for(primitives,l) {
          const CImg<tf>& primitive = primitives[l];
          switch (primitive.size()) {
          case 1 : { // Point
            const unsigned int
              i0 = (unsigned int)primitive(0);
            const float
              x0 = (float)vertices(i0,0), y0 = (float)vertices(i0,1), z0 = (float)vertices(i0,2);
            p_centers(l,0) = X + x0; p_centers(l,1) = Y + y0; p_centers(l,2) = Z + z0;
            p_normals(l,0) = p_normals(l,1) = p_normals(l,2) = 0;
          } break;
          case 2 : case 5 : { // Segment and sphere
            const unsigned int
              i0 = (unsigned int)primitive(0),
              i1 = (unsigned int)primitive(1);
            const float
              x0 = (float)vertices(i0,0), y0 = (float)vertices(i0,1), z0 = (float)vertices(i0,2),
              x1 = (float)vertices(i1,0), y1 = (float)vertices(i1,1), z1 = (float)vertices(i1,2);
            p_centers(l,0) = X + (x0 + x1)/2; p_centers(l,1) = Y + (y0 + y1)/2; p_centers(l,2) = Z + (z0 + z1)/2;
            p_normals(l,0) = p_normals(l,1) = p_normals(l,2) = 0;
          } break;
          case 3 : case 9 : { // Triangle
            const unsigned int
              i0 = (unsigned int)primitive(0),
              i1 = (unsigned int)primitive(1),
              i2 = (unsigned int)primitive(2);
            const float
              x0 = (float)vertices(i0,0), y0 = (float)vertices(i0,1), z0 = (float)vertices(i0,2),
              x1 = (float)vertices(i1,0), y1 = (float)vertices(i1,1), z1 = (float)vertices(i1,2),
              x2 = (float)vertices(i2,0), y2 = (float)vertices(i2,1), z2 = (float)vertices(i2,2),
              dx01 = x1 - x0, dy01 = y1 - y0, dz01 = z1 - z0,
              dx02 = x2 - x0, dy02 = y2 - y0, dz02 = z2 - z0,
              u = dy01*dz02 - dz01*dy02,
              v = dz01*dx02 - dx01*dz02,
              w = dx01*dy02 - dy01*dx02,
              nn = 1e-5f + cimg::hypot(u,v,w),
              nu = u/nn, nv = v/nn, nw = w/nn;
            p_centers(l,0) = X + (x0 + x1 + x2)/3;
            p_centers(l,1) = Y + (y0 + y1 + y2)/3;
            p_centers(l,2) = Z + (z0 + z1 + z2)/3;
            p_normals(l,0) = nu; p_normals(l,1) = nv; p_normals(l,2) = nw;
          } break;
          case 4 : case 12 : { // Quadrangle
            const unsigned int
              i0 = (unsigned int)primitive(0),
              i1 = (unsigned int)primitive(1),
              i2 = (unsigned int)primitive(2),
              i3 = (unsigned int)primitive(3);
            const float
              x0 = (float)vertices(i0,0), y0 = (float)vertices(i0,1), z0 = (float)vertices(i0,2),
              x1 = (float)vertices(i1,0), y1 = (float)vertices(i1,1), z1 = (float)vertices(i1,2),
              x2 = (float)vertices(i2,0), y2 = (float)vertices(i2,1), z2 = (float)vertices(i2,2),
              x3 = (float)vertices(i3,0), y3 = (float)vertices(i3,1), z3 = (float)vertices(i3,2),
              dx01 = x1 - x0, dy01 = y1 - y0, dz01 = z1 - z0,
              dx02 = x2 - x0, dy02 = y2 - y0, dz02 = z2 - z0,
              dx03 = x3 - x0, dy03 = y3 - y0, dz03 = z3 - z0,
              u0 = dy01*dz02 - dz01*dy02,
              v0 = dz01*dx02 - dx01*dz02,
              w0 = dx01*dy02 - dy01*dx02,
              nn0 = 1e-5f + cimg::hypot(u0,v0,w0),
              nu0 = u0/nn0, nv0 = v0/nn0, nw0 = w0/nn0,
              u1 = dy02*dz03 - dz02*dy03,
              v1 = dz02*dx03 - dx02*dz03,
              w1 = dx02*dy03 - dy02*dx03,
              nn1 = 1e-5f + cimg::hypot(u1,v1,w1),
              nu1 = u1/nn1, nv1 = v1/nn1, nw1 = w1/nn1,
              u = nu0 + nu1, v = nv0 + nv1, w = nw0 + nw1,
              nn = 1e-5f + cimg::hypot(u,v,w),
              nu = u/nn, nv = v/nn, nw = w/nn;
            p_centers(l,0) = X + (x0 + x1 + x2 + x3)/4;
            p_centers(l,1) = Y + (y0 + y1 + y2 + y3)/4;
            p_centers(l,2) = Z + (z0 + z1 + z2 + z3)/4;
            p_normals(l,0) = nu; p_normals(l,1) = nv; p_normals(l,2) = nw;
          } break;
          default : // Other types of primitives (should never happen...)
            p_centers(l,0) = p_centers(l,1) = p_centers(l,2) =
              p_normals(l,0) = p_normals(l,1) = p_normals(l,2) = 0;
          }
        }

        // 3D normals to vertices.
        if (render_type>=4) {
          v_normals.assign(vertices._width,3,1,1,0);
          cimglist_for(primitives,l) {
            const CImg<tf>& primitive = primitives[l];
            const float u = p_normals(l,0), v = p_normals(l,1), w = p_normals(l,2);
            switch (primitive.size()) {
            case 3 : case 9 : { // Triangle
              const unsigned int
                i0 = (unsigned int)primitive(0),
                i1 = (unsigned int)primitive(1),
                i2 = (unsigned int)primitive(2);
              v_normals(i0,0)+=u; v_normals(i0,1)+=v; v_normals(i0,2)+=w;
              v_normals(i1,0)+=u; v_normals(i1,1)+=v; v_normals(i1,2)+=w;
              v_normals(i2,0)+=u; v_normals(i2,1)+=v; v_normals(i2,2)+=w;
            } break;
            case 4 : case 12 : { // Quadrangle
              const unsigned int
                i0 = (unsigned int)primitive(0),
                i1 = (unsigned int)primitive(1),
                i2 = (unsigned int)primitive(2),
                i3 = (unsigned int)primitive(3);
              v_normals(i0,0)+=u; v_normals(i0,1)+=v; v_normals(i0,2)+=w;
              v_normals(i1,0)+=u; v_normals(i1,1)+=v; v_normals(i1,2)+=w;
              v_normals(i2,0)+=u; v_normals(i2,1)+=v; v_normals(i2,2)+=w;
              v_normals(i3,0)+=u; v_normals(i3,1)+=v; v_normals(i3,2)+=w;
            } break;
            }
          }
          cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                         v_normals.width()>=cimg_openmp_sizefactor*4096))
          cimg_forX(v_normals,l) {
            const float
              u = v_normals(l,0), v = v_normals(l,1), w = v_normals(l,2),
              nn = 1e-5f + cimg::hypot(u,v,w),
              nu = u/nn, nv = v/nn, nw = w/nn;
            v_normals(l,0) = nu; v_normals(l,1) = nv; v_normals(l,2) = nw;
          }
        }
      }

      // Compute 3D to 2D projection.
      CImg<floatT> projections(vertices._width,2);
      if (focal) {
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                       projections.size()>=cimg_openmp_sizefactor*4096))
        cimg_forX(projections,l) { // Perspective projection
          const float
            x = (float)vertices(l,0), y = (float)vertices(l,1), z = (float)vertices(l,2),
            z_denom = z + Z + _focal;
          projections(l,1) = Y + _focal*y/z_denom;
          projections(l,0) = X + _focal*x/z_denom;
        }
      } else {
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                       projections.size()>=cimg_openmp_sizefactor*4096))
        cimg_forX(projections,l) { // Parallel projection
          const float x = (float)vertices(l,0), y = (float)vertices(l,1);
          projections(l,1) = Y + y;
          projections(l,0) = X + x;
        }
      }

      float zmax = 0;
      if (zbuffer) zmax = vertices.get_shared_row(2).max();

      // Compute visible primitives.
      CImg<uintT> visibles(primitives._width,1,1,1,~0U);
      CImg<floatT> zrange(primitives._width);
      const float zmin = focal?1 - _focal:cimg::type<float>::min();
      bool is_forward = zbuffer?true:false;
      cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                     primitives.size()>=cimg_openmp_sizefactor*4096))
      cimglist_for(primitives,l) {
        const CImg<tf>& primitive = primitives[l];
        switch (primitive.size()) {
        case 1 : { // Point
          CImg<_to> _opacity;
          __draw_object3d(opacities,l,_opacity);
          if (l<=colors.width() && (colors[l].size()!=_spectrum || _opacity)) is_forward = false;
          const unsigned int i0 = (unsigned int)primitive(0);
          const float z0 = Z + (float)vertices(i0,2);
          if (z0>=zmin) {
            visibles(l) = (unsigned int)l;
            zrange(l) = z0;
          }
        } break;
        case 5 : { // Sphere
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1);
          const float
            Xc = 0.5f*((float)vertices(i0,0) + (float)vertices(i1,0)),
            Yc = 0.5f*((float)vertices(i0,1) + (float)vertices(i1,1)),
            Zc = 0.5f*((float)vertices(i0,2) + (float)vertices(i1,2)),
            _zc = Z + Zc,
            zc = _zc + _focal,
            xc = X + Xc*(focal?_focal/zc:1),
            yc = Y + Yc*(focal?_focal/zc:1),
            radius = 0.5f*cimg::hypot(vertices(i1,0) - vertices(i0,0),
                                      vertices(i1,1) - vertices(i0,1),
                                      vertices(i1,2) - vertices(i0,2))*(focal?_focal/zc:1),
            xm = xc - radius,
            ym = yc - radius,
            xM = xc + radius,
            yM = yc + radius;
          if (xM>=0 && xm<_width && yM>=0 && ym<_height && _zc>=zmin) {
            visibles(l) = (unsigned int)l;
            zrange(l) = _zc;
          }
          is_forward = false;
        } break;
        case 2 : case 6 : { // Segment
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1);
          const float
            x0 = projections(i0,0), y0 = projections(i0,1), z0 = Z + (float)vertices(i0,2),
            x1 = projections(i1,0), y1 = projections(i1,1), z1 = Z + (float)vertices(i1,2);
          float xm, xM, ym, yM, zm, zM;
          if (x0<x1) { xm = x0; xM = x1; } else { xm = x1; xM = x0; }
          if (y0<y1) { ym = y0; yM = y1; } else { ym = y1; yM = y0; }
          if (z0<z1) { zm = z0; zM = z1; } else { zm = z1; zM = z0; }
          if ((zm>=zmin && xM>=0 && xm<_width && yM>=0 && ym<_height) || (zm<zmin && zM>=zmin)) {
            visibles(l) = (unsigned int)l;
            zrange(l) = (z0 + z1)/2;
          }
        } break;
        case 3 : case 9 : { // Triangle
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1),
            i2 = (unsigned int)primitive(2);
          const float
            x0 = projections(i0,0), y0 = projections(i0,1), z0 = Z + (float)vertices(i0,2),
            x1 = projections(i1,0), y1 = projections(i1,1), z1 = Z + (float)vertices(i1,2),
            x2 = projections(i2,0), y2 = projections(i2,1), z2 = Z + (float)vertices(i2,2);
          float dot = -1;
          if (p_normals) {
            if (focal) {
              const float
                cam2obj_x = p_centers(l,0) - X,
                cam2obj_y = p_centers(l,1) - Y,
                cam2obj_z = p_centers(l,2) + _focal;
              dot = cam2obj_x*p_normals(l,0) + cam2obj_y*p_normals(l,1) + cam2obj_z*p_normals(l,2);
            } else dot = p_normals(l,2);
          }
          float xm, xM, ym, yM, zm, zM;
          if (x0<x1) { xm = x0; xM = x1; } else { xm = x1; xM = x0; }
          if (x2<xm) xm = x2;
          if (x2>xM) xM = x2;
          if (y0<y1) { ym = y0; yM = y1; } else { ym = y1; yM = y0; }
          if (y2<ym) ym = y2;
          if (y2>yM) yM = y2;
          if (z0<z1) { zm = z0; zM = z1; } else { zm = z1; zM = z0; }
          if (z2<zm) zm = z2;
          if (z2>zM) zM = z2;
          if (((zm>=zmin && xM>=0 && xm<_width && yM>=0 && ym<_height) || (zm<zmin && zM>=zmin)) &&
              (is_double_sided || dot<0)) {
            visibles(l) = (unsigned int)l;
            zrange(l) = (z0 + z1 + z2)/3;
          }
        } break;
        case 4 : case 12 : { // Quadrangle
          const unsigned int
            i0 = (unsigned int)primitive(0),
            i1 = (unsigned int)primitive(1),
            i2 = (unsigned int)primitive(2),
            i3 = (unsigned int)primitive(3);
          const float
            x0 = projections(i0,0), y0 = projections(i0,1), z0 = Z + (float)vertices(i0,2),
            x1 = projections(i1,0), y1 = projections(i1,1), z1 = Z + (float)vertices(i1,2),
            x2 = projections(i2,0), y2 = projections(i2,1), z2 = Z + (float)vertices(i2,2),
            x3 = projections(i3,0), y3 = projections(i3,1), z3 = Z + (float)vertices(i3,2);
          float dot = -1;
          if (p_normals) {
            if (focal) {
              const float
                cam2obj_x = p_centers(l,0) - X,
                cam2obj_y = p_centers(l,1) - Y,
                cam2obj_z = p_centers(l,2) + _focal;
              dot = cam2obj_x*p_normals(l,0) + cam2obj_y*p_normals(l,1) + cam2obj_z*p_normals(l,2);
            } else dot = p_normals(l,2);
          }
          float xm, xM, ym, yM, zm, zM;
          if (x0<x1) { xm = x0; xM = x1; } else { xm = x1; xM = x0; }
          if (x2<xm) xm = x2;
          if (x2>xM) xM = x2;
          if (x3<xm) xm = x3;
          if (x3>xM) xM = x3;
          if (y0<y1) { ym = y0; yM = y1; } else { ym = y1; yM = y0; }
          if (y2<ym) ym = y2;
          if (y2>yM) yM = y2;
          if (y3<ym) ym = y3;
          if (y3>yM) yM = y3;
          if (z0<z1) { zm = z0; zM = z1; } else { zm = z1; zM = z0; }
          if (z2<zm) zm = z2;
          if (z2>zM) zM = z2;
          if (z3<zm) zm = z3;
          if (z3>zM) zM = z3;
          if (((zm>=zmin && xM>=0 && xm<_width && yM>=0 && ym<_height) || (zm<zmin && zM>=zmin)) &&
              (is_double_sided || dot<0)) {
            visibles(l) = (unsigned int)l;
            zrange(l) = (z0 + z1 + z2 + z3)/4;
          }
        } break;
        default :
          if (render_type==5) cimg::mutex(10,0);
          throw CImgArgumentException(_cimg_instance
                                      "draw_object3d(): Invalid primitive[%u] with size %u "
                                      "(should have size 1,2,3,4,5,6,9 or 12).",
                                      cimg_instance,
                                      l,primitive.size());
        }
      }

      // Force transparent primitives to be drawn last when zbuffer is activated
      // (and if object contains no spheres or sprites).
      if (is_forward)
        cimglist_for(primitives,l)
          if (___draw_object3d(opacities,l)!=1) zrange(l) = 2*zmax - zrange(l);

      // Sort only visibles primitives.
      unsigned int *p_visibles = visibles._data;
      float *p_zrange = zrange._data;
      const float *ptrz = p_zrange;
      cimg_for(visibles,ptr,unsigned int) {
        if (*ptr!=~0U) { *(p_visibles++) = *ptr; *(p_zrange++) = *ptrz; }
        ++ptrz;
      }
      const unsigned int nb_visibles = (unsigned int)(p_zrange - zrange._data);
      if (!nb_visibles) {
        if (render_type==5) cimg::mutex(10,0);
        return *this;
      }
      CImg<uintT> permutations;
      CImg<floatT>(zrange._data,nb_visibles,1,1,1,true).sort(permutations,is_forward);

      // Compute light properties.
      CImg<floatT> lightprops;
      switch (render_type) {
      case 3 : { // Flat Shading
        lightprops.assign(nb_visibles);
        cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                       nb_visibles>=cimg_openmp_sizefactor*4096))
        cimg_forX(lightprops,l) {
          const unsigned int p = visibles(permutations(l));
          const CImg<tf>& primitive = primitives[p];
          const unsigned int psize = (unsigned int)primitive.size();
          if (psize==3 || psize==4 || psize==9 || psize==12) {
            const float
              x = (float)p_centers(p,0), y = (float)p_centers(p,1), z = (float)p_centers(p,2),
              u = (float)p_normals(p,0), v = (float)p_normals(p,1), w = (float)p_normals(p,2),
              lx = lightx - x, ly = lighty - y, lz = lightz - z,
              nn = 1e-5f + cimg::hypot(lx,ly,lz),
              nlx = lx/nn, nly = ly/nn, nlz = lz/nn,
              dot = nlx*u + nly*v + nlz*w,
              factor = std::max(0.15f,is_double_sided?cimg::abs(dot):std::max(0.0f,dot));
            lightprops[l] = factor<=nspec?factor:(nsl1*factor*factor + nsl2*factor + nsl3);
          } else lightprops[l] = 1;
        }
      } break;
      case 4 : // Gouraud Shading
      case 5 : { // Phong-Shading
        if (render_type==4) {
          lightprops.assign(vertices._width);
          cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                         nb_visibles>=cimg_openmp_sizefactor*4096))
          cimg_forX(lightprops,l) {
            const float
              x = vertices(l,0), y = vertices(l,1), z = vertices(l,2),
              u = v_normals(l,0), v = v_normals(l,1), w = v_normals(l,2),
              lx = lightx - x - X, ly = lighty - y - Y, lz = lightz - z - Z,
              nn = 1e-5f + cimg::hypot(lx,ly,lz),
              nlx = lx/nn, nly = ly/nn, nlz = lz/nn,
              dot = nlx*u + nly*v + nlz*w,
              factor = std::max(0.15f,is_double_sided?cimg::abs(dot):std::max(0.0f,dot));
            lightprops[l] = factor<=nspec?factor:(nsl1*factor*factor + nsl2*factor + nsl3);
          }
        } else {
          const unsigned int
            lw2 = light_texture._width/2 - 1,
            lh2 = light_texture._height/2 - 1;
          lightprops.assign(vertices._width,2);
          cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                         nb_visibles>=cimg_openmp_sizefactor*4096))
          cimg_forX(lightprops,l) {
            const float u = v_normals(l,0), v = v_normals(l,1);
            lightprops(l,0) = lw2*(1 + u);
            lightprops(l,1) = lh2*(1 + v);
          }
        }
      } break;
      }

      // Draw visible primitives.
      const CImg<tc> default_color(1,_spectrum,1,1,(tc)200);
      cimg_pragma_openmp(parallel for cimg_openmp_if(is_multithreaded_rendering &&
                                                     nb_visibles>=cimg_openmp_sizefactor*256))
      for (int l = 0; l<(int)nb_visibles; ++l) {
        CImg<_to> _opacity;
        const unsigned int n_primitive = visibles(permutations(l));
        const CImg<tf>& primitive = primitives[n_primitive];
        const CImg<tc>
          &__color = n_primitive<colors._width?colors[n_primitive]:CImg<tc>(),
          _color = (__color && __color.size()!=_spectrum && __color._spectrum<_spectrum)?
            __color.get_resize(-100,-100,-100,_spectrum,0):CImg<tc>(),
          &color = _color?_color:(__color?__color:default_color);
        const tc *const pcolor = color._data;
        float opacity = __draw_object3d(opacities,n_primitive,_opacity);
        if (_opacity.is_empty()) opacity*=g_opacity;

        switch (primitive.size()) {
        case 1 : { // Colored point or sprite
          const unsigned int n0 = (unsigned int)primitive[0];
          const int x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1));

          if (_opacity.is_empty()) { // Scalar opacity
            if (color.size()==_spectrum) // Colored point
              draw_point(x0,y0,pcolor,opacity);
            else { // Sprite
              const float
                z = Z + (float)vertices(n0,2),
                factor = focal<0?1:sprite_scale*(focal?_focal/(z + _focal):1);
              const unsigned int
                _sw = (unsigned int)(color._width*factor),
                _sh = (unsigned int)(color._height*factor),
                sw = _sw?_sw:1, sh = _sh?_sh:1;
              const int nx0 = x0 - (int)sw/2, ny0 = y0 - (int)sh/2;
              if (sw<=3*_width/2 && sh<=3*_height/2 &&
                  (nx0 + (int)sw/2>=0 || nx0 - (int)sw/2<width() || ny0 + (int)sh/2>=0 || ny0 - (int)sh/2<height())) {
                const CImg<tc>
                  _sprite = (sw!=color._width || sh!=color._height)?
                    color.get_resize(sw,sh,1,-100,render_type<=3?1:3):CImg<tc>(),
                  &sprite = _sprite?_sprite:color;
                draw_image(nx0,ny0,sprite,opacity);
              }
            }
          } else { // Opacity mask
            const float
              z = Z + (float)vertices(n0,2),
              factor = focal<0?1:sprite_scale*(focal?_focal/(z + _focal):1);
            const unsigned int
              _sw = (unsigned int)(std::max(color._width,_opacity._width)*factor),
              _sh = (unsigned int)(std::max(color._height,_opacity._height)*factor),
              sw = _sw?_sw:1, sh = _sh?_sh:1;
            const int nx0 = x0 - (int)sw/2, ny0 = y0 - (int)sh/2;
            if (sw<=3*_width/2 && sh<=3*_height/2 &&
                (nx0 + (int)sw/2>=0 || nx0 - (int)sw/2<width() || ny0 + (int)sh/2>=0 || ny0 - (int)sh/2<height())) {
              const CImg<tc>
                _sprite = (sw!=color._width || sh!=color._height)?
                  color.get_resize(sw,sh,1,-100,render_type<=3?1:3):CImg<tc>(),
                &sprite = _sprite?_sprite:color;
              const CImg<_to>
                _nopacity = (sw!=_opacity._width || sh!=_opacity._height)?
                  _opacity.get_resize(sw,sh,1,-100,render_type<=3?1:3):CImg<_to>(),
                &nopacity = _nopacity?_nopacity:_opacity;
              draw_image(nx0,ny0,sprite,nopacity,g_opacity);
            }
          }
        } break;
        case 2 : { // Colored segment
          unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1];
          if (render_type)
            _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,pcolor,opacity,_focal);
          else {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1));
            draw_point(x0,y0,pcolor,opacity).draw_point(x1,y1,pcolor,opacity);
          }
        } break;
        case 5 : { // Colored sphere
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1],
            is_wireframe = (unsigned int)primitive[2],
            is_radius = (unsigned int)primitive[3];
          float Xc,Yc,Zc,radius;
          if (is_radius) {
            Xc = (float)vertices(n0,0);
            Yc = (float)vertices(n0,1);
            Zc = (float)vertices(n0,2);
            radius = cimg::hypot(vertices(n1,0) - vertices(n0,0),
                                 vertices(n1,1) - vertices(n0,1),
                                 vertices(n1,2) - vertices(n0,2));
          } else {
            Xc = 0.5f*((float)vertices(n0,0) + (float)vertices(n1,0));
            Yc = 0.5f*((float)vertices(n0,1) + (float)vertices(n1,1));
            Zc = 0.5f*((float)vertices(n0,2) + (float)vertices(n1,2));
            radius = 0.5f*cimg::hypot(vertices(n1,0) - vertices(n0,0),
                                      vertices(n1,1) - vertices(n0,1),
                                      vertices(n1,2) - vertices(n0,2));
          }
          const float
            zc = Z + Zc + _focal,
            af = focal?_focal/zc:1,
            xc = X + Xc*af,
            yc = Y + Yc*af;
          radius*=af;

          switch (render_type) {
          case 0 :
            draw_point((int)xc,(int)yc,pcolor,opacity);
            break;
          case 1 :
            draw_circle((int)xc,(int)yc,(int)radius,pcolor,opacity,~0U);
            break;
          default :
            if (is_wireframe) draw_circle((int)xc,(int)yc,(int)radius,pcolor,opacity,~0U);
            else draw_circle((int)xc,(int)yc,(int)radius,pcolor,opacity);
            break;
          }
        } break;
        case 6 : { // Textured segment
          if (!__color) {
            if (render_type==5) cimg::mutex(10,0);
            throw CImgArgumentException(_cimg_instance
                                        "draw_object3d(): Undefined texture for segment primitive [%u].",
                                        cimg_instance,n_primitive);
          }
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1];
          const int
            tx0 = (int)primitive[2], ty0 = (int)primitive[3],
            tx1 = (int)primitive[4], ty1 = (int)primitive[5];
          if (render_type)
            _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,
                                                 color,tx0,ty0,tx1,ty1,opacity,_focal);
          else {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1));
            draw_point(x0,y0,color.get_vector_at(tx0<=0?0:tx0>=color.width()?color.width() - 1:tx0,
                                                 ty0<=0?0:ty0>=color.height()?color.height() - 1:ty0)._data,opacity).
              draw_point(x1,y1,color.get_vector_at(tx1<=0?0:tx1>=color.width()?color.width() - 1:tx1,
                                                   ty1<=0?0:ty1>=color.height()?color.height() - 1:ty1)._data,opacity);
          }
        } break;
        case 3 : { // Colored triangle
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1],
            n2 = (unsigned int)primitive[2];
          switch (render_type) {
          case 0 : {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
              x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
            draw_point(x0,y0,pcolor,opacity).draw_point(x1,y1,pcolor,opacity).draw_point(x2,y2,pcolor,opacity);
          } break;
          case 1 :
            _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,pcolor,opacity,_focal).
              _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n1,n2,vertices,projections,pcolor,opacity,_focal).
              _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n2,n0,vertices,projections,pcolor,opacity,_focal);
            break;
          case 2 :
            _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,pcolor,opacity,1,_focal);
            break;
          case 3 :
            _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,pcolor,opacity,
                                                 lightprops(l),_focal);
            break;
          case 4 :
            _draw_object3d_gouraud_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                    pcolor,lightprops(n0),lightprops(n1),lightprops(n2),opacity,
                                                    _focal);
            break;
          case 5 : {
            const int
              lx0 = cimg::uiround(lightprops(n0,0)), ly0 = cimg::uiround(lightprops(n0,1)),
              lx1 = cimg::uiround(lightprops(n1,0)), ly1 = cimg::uiround(lightprops(n1,1)),
              lx2 = cimg::uiround(lightprops(n2,0)), ly2 = cimg::uiround(lightprops(n2,1));
            _draw_object3d_phong_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  pcolor,light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity,_focal);
          } break;
          }
        } break;
        case 4 : { // Colored quadrangle
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1],
            n2 = (unsigned int)primitive[2],
            n3 = (unsigned int)primitive[3];
          switch (render_type) {
          case 0 : {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
              x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1)),
              x3 = cimg::uiround(projections(n3,0)), y3 = cimg::uiround(projections(n3,1));
            draw_point(x0,y0,pcolor,opacity).draw_point(x1,y1,pcolor,opacity).
              draw_point(x2,y2,pcolor,opacity).draw_point(x3,y3,pcolor,opacity);
          } break;
          case 1 :
            _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,pcolor,opacity,_focal).
              _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n1,n2,vertices,projections,pcolor,opacity,_focal).
              _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n2,n3,vertices,projections,pcolor,opacity,_focal).
              _draw_object3d_flat_colored_segment(zbuffer,X,Y,Z,n3,n0,vertices,projections,pcolor,opacity,_focal);
            break;
          case 2 :
            _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,pcolor,opacity,1,_focal).
              _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,pcolor,opacity,1,
                                                   _focal);
            break;
          case 3 :
            _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,pcolor,opacity,
                                                 lightprops(l),_focal).
              _draw_object3d_flat_colored_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,pcolor,opacity,
                                                   lightprops(l),_focal);
            break;
          case 4 :
            _draw_object3d_gouraud_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                    pcolor,lightprops(n0),lightprops(n1),lightprops(n2),opacity,
                                                    _focal).
              _draw_object3d_gouraud_colored_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                      pcolor,lightprops(n0),lightprops(n2),lightprops(n3),opacity,
                                                      _focal);
            break;
          case 5 : {
            const int
              lx0 = cimg::uiround(lightprops(n0,0)), ly0 = cimg::uiround(lightprops(n0,1)),
              lx1 = cimg::uiround(lightprops(n1,0)), ly1 = cimg::uiround(lightprops(n1,1)),
              lx2 = cimg::uiround(lightprops(n2,0)), ly2 = cimg::uiround(lightprops(n2,1)),
              lx3 = cimg::uiround(lightprops(n3,0)), ly3 = cimg::uiround(lightprops(n3,1));
            _draw_object3d_phong_colored_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  pcolor,light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity,_focal).
              _draw_object3d_phong_colored_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                    pcolor,light_texture,lx0,ly0,lx2,ly2,lx3,ly3,opacity,_focal);
          } break;
          }
        } break;
        case 9 : { // Textured triangle
          if (!__color) {
            if (render_type==5) cimg::mutex(10,0);
            throw CImgArgumentException(_cimg_instance
                                        "draw_object3d(): Undefined texture for triangle primitive [%u].",
                                        cimg_instance,n_primitive);
          }
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1],
            n2 = (unsigned int)primitive[2];
          const int
            tx0 = (int)primitive[3], ty0 = (int)primitive[4],
            tx1 = (int)primitive[5], ty1 = (int)primitive[6],
            tx2 = (int)primitive[7], ty2 = (int)primitive[8];
          switch (render_type) {
          case 0 : {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
              x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1));
            draw_point(x0,y0,color.get_vector_at(tx0<=0?0:tx0>=color.width()?color.width() - 1:tx0,
                                                 ty0<=0?0:ty0>=color.height()?color.height() - 1:ty0)._data,opacity).
              draw_point(x1,y1,color.get_vector_at(tx1<=0?0:tx1>=color.width()?color.width() - 1:tx1,
                                                   ty1<=0?0:ty1>=color.height()?color.height() - 1:ty1)._data,opacity).
              draw_point(x2,y2,color.get_vector_at(tx2<=0?0:tx2>=color.width()?color.width() - 1:tx2,
                                                   ty2<=0?0:ty2>=color.height()?color.height() - 1:ty2)._data,opacity);
          } break;
          case 1 :
            _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,
                                                 color,tx0,ty0,tx1,ty1,opacity,_focal).
              _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n1,n2,vertices,projections,
                                                   color,tx1,ty1,tx2,ty2,opacity,_focal).
              _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n2,n0,vertices,projections,
                                                   color,tx2,ty2,tx0,ty0,opacity,_focal);
            break;
          case 2 :
            _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  color,tx0,ty0,tx1,ty1,tx2,ty2,opacity,1,_focal);
            break;
          case 3 :
            _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  color,tx0,ty0,tx1,ty1,tx2,ty2,opacity,lightprops(l),_focal);
            break;
          case 4 :
            _draw_object3d_gouraud_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                     color,tx0,ty0,tx1,ty1,tx2,ty2,
                                                     lightprops(n0),lightprops(n1),lightprops(n2),opacity,_focal);
            break;
          case 5 :
            const int
              lx0 = cimg::uiround(lightprops(n0,0)), ly0 = cimg::uiround(lightprops(n0,1)),
              lx1 = cimg::uiround(lightprops(n1,0)), ly1 = cimg::uiround(lightprops(n1,1)),
              lx2 = cimg::uiround(lightprops(n2,0)), ly2 = cimg::uiround(lightprops(n2,1));
            _draw_object3d_phong_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                   color,tx0,ty0,tx1,ty1,tx2,ty2,
                                                   light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity,_focal);
            break;
          }
        } break;
        case 12 : { // Textured quadrangle
          if (!__color) {
            if (render_type==5) cimg::mutex(10,0);
            throw CImgArgumentException(_cimg_instance
                                        "draw_object3d(): Undefined texture for quadrangle primitive [%u].",
                                        cimg_instance,n_primitive);
          }
          const unsigned int
            n0 = (unsigned int)primitive[0],
            n1 = (unsigned int)primitive[1],
            n2 = (unsigned int)primitive[2],
            n3 = (unsigned int)primitive[3];
          const int
            tx0 = (int)primitive[4], ty0 = (int)primitive[5],
            tx1 = (int)primitive[6], ty1 = (int)primitive[7],
            tx2 = (int)primitive[8], ty2 = (int)primitive[9],
            tx3 = (int)primitive[10], ty3 = (int)primitive[11];
          switch (render_type) {
          case 0 : {
            const int
              x0 = cimg::uiround(projections(n0,0)), y0 = cimg::uiround(projections(n0,1)),
              x1 = cimg::uiround(projections(n1,0)), y1 = cimg::uiround(projections(n1,1)),
              x2 = cimg::uiround(projections(n2,0)), y2 = cimg::uiround(projections(n2,1)),
              x3 = cimg::uiround(projections(n3,0)), y3 = cimg::uiround(projections(n3,1));
            draw_point(x0,y0,color.get_vector_at(tx0<=0?0:tx0>=color.width()?color.width() - 1:tx0,
                                                 ty0<=0?0:ty0>=color.height()?color.height() - 1:ty0)._data,opacity).
              draw_point(x1,y1,color.get_vector_at(tx1<=0?0:tx1>=color.width()?color.width() - 1:tx1,
                                                   ty1<=0?0:ty1>=color.height()?color.height() - 1:ty1)._data,opacity).
              draw_point(x2,y2,color.get_vector_at(tx2<=0?0:tx2>=color.width()?color.width() - 1:tx2,
                                                   ty2<=0?0:ty2>=color.height()?color.height() - 1:ty2)._data,opacity).
              draw_point(x3,y3,color.get_vector_at(tx3<=0?0:tx3>=color.width()?color.width() - 1:tx3,
                                                   ty3<=0?0:ty3>=color.height()?color.height() - 1:ty3)._data,opacity);
          } break;
          case 1 :
            _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n0,n1,vertices,projections,
                                                 color,tx0,ty0,tx1,ty1,opacity,_focal).
              _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n1,n2,vertices,projections,
                                                   color,tx1,ty1,tx2,ty2,opacity,_focal).
              _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n2,n3,vertices,projections,
                                                   color,tx2,ty2,tx3,ty3,opacity,_focal).
              _draw_object3d_flat_textured_segment(zbuffer,X,Y,Z,n3,n0,vertices,projections,
                                                   color,tx3,ty3,tx0,ty0,opacity,_focal);
            break;
          case 2 :
            _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  color,tx0,ty0,tx1,ty1,tx2,ty2,opacity,1,_focal).
              _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                    color,tx0,ty0,tx2,ty2,tx3,ty3,opacity,1,_focal);
            break;
          case 3 :
            _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                  color,tx0,ty0,tx1,ty1,tx2,ty2,opacity,lightprops(l),_focal).
              _draw_object3d_flat_textured_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                    color,tx0,ty0,tx2,ty2,tx3,ty3,opacity,lightprops(l),_focal);
            break;
          case 4 :
            _draw_object3d_gouraud_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                     color,tx0,ty0,tx1,ty1,tx2,ty2,
                                                     lightprops(n0),lightprops(n1),lightprops(n2),opacity,_focal).
              _draw_object3d_gouraud_textured_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                       color,tx0,ty0,tx2,ty2,tx3,ty3,
                                                       lightprops(n0),lightprops(n2),lightprops(n3),opacity,_focal);
            break;
          case 5 : {
            const int
              lx0 = cimg::uiround(lightprops(n0,0)), ly0 = cimg::uiround(lightprops(n0,1)),
              lx1 = cimg::uiround(lightprops(n1,0)), ly1 = cimg::uiround(lightprops(n1,1)),
              lx2 = cimg::uiround(lightprops(n2,0)), ly2 = cimg::uiround(lightprops(n2,1)),
              lx3 = cimg::uiround(lightprops(n3,0)), ly3 = cimg::uiround(lightprops(n3,1));
            _draw_object3d_phong_textured_triangle(zbuffer,X,Y,Z,n0,n1,n2,vertices,projections,
                                                   color,tx0,ty0,tx1,ty1,tx2,ty2,
                                                   light_texture,lx0,ly0,lx1,ly1,lx2,ly2,opacity,_focal).
              _draw_object3d_phong_textured_triangle(zbuffer,X,Y,Z,n0,n2,n3,vertices,projections,
                                                     color,tx0,ty0,tx2,ty2,tx3,ty3,
                                                     light_texture,lx0,ly0,lx2,ly2,lx3,ly3,opacity,_focal);
          } break;
          }
        } break;
        }
      }
      if (render_type==5) cimg::mutex(10,0);
      return *this;
    }

    //@}
    //---------------------------
    //
    //! \name Data Input
    //@{
    //---------------------------

    //! Launches a simple interface to select a shape from an image.
    /**
       \param disp Display window to use.
       \param feature_type Type of feature to select. Can be <tt>{ 0=point | 1=line | 2=rectangle | 3=ellipse }</tt>.
       \param XYZ Pointer to 3 values X,Y,Z which indicate the projection point coordinates, for volumetric images.
       \param exit_on_anykey Exit function when any key is pressed.
       \param is_deep_selection_default
    **/
    CImg<T>& select(CImgDisplay &disp,
                    const unsigned int feature_type=2, unsigned int *const XYZ=0,
                    const bool exit_on_anykey=false,
                    const bool is_deep_selection_default=false) {
      return get_select(disp,feature_type,XYZ,exit_on_anykey,is_deep_selection_default).move_to(*this);
    }

    //! Simple interface to select a shape from an image \overload.
    CImg<T>& select(const char *const title,
                    const unsigned int feature_type=2, unsigned int *const XYZ=0,
                    const bool exit_on_anykey=false,
                    const bool is_deep_selection_default=false) {
      return get_select(title,feature_type,XYZ,exit_on_anykey,is_deep_selection_default).move_to(*this);
    }

    //! Simple interface to select a shape from an image \newinstance.
    CImg<intT> get_select(CImgDisplay &disp,
                          const unsigned int feature_type=2, unsigned int *const XYZ=0,
                          const bool exit_on_anykey=false,
                          const bool is_deep_selection_default=false) const {
      return _select(disp,0,feature_type,XYZ,0,0,0,exit_on_anykey,true,false,is_deep_selection_default);
    }

    //! Simple interface to select a shape from an image \newinstance.
    CImg<intT> get_select(const char *const title,
                          const unsigned int feature_type=2, unsigned int *const XYZ=0,
                          const bool exit_on_anykey=false,
                          const bool is_deep_selection_default=false) const {
      CImgDisplay disp;
      return _select(disp,title,feature_type,XYZ,0,0,0,exit_on_anykey,true,false,is_deep_selection_default);
    }

    CImg<intT> _select(CImgDisplay &disp, const char *const title,
                       const unsigned int feature_type, unsigned int *const XYZ,
                       const int origX, const int origY, const int origZ,
                       const bool exit_on_anykey,
                       const bool reset_view3d,
                       const bool force_display_z_coord,
                       const bool is_deep_selection_default) const {
      if (is_empty()) return CImg<intT>(1,feature_type==0?3:6,1,1,-1);
      if (!disp) {
        disp.assign(cimg_fitscreen(_width,_height,_depth),title?title:0,1);
        if (!title) disp.set_title("CImg<%s> (%ux%ux%ux%u)",pixel_type(),_width,_height,_depth,_spectrum);
      } else {
        if (title) disp.set_title("%s",title);
        disp.move_inside_screen();
      }

      CImg<T> thumb;
      if (width()>disp.screen_width() || height()>disp.screen_height())
        get_resize(cimg_fitscreen(width(),height(),depth()),depth(),-100).move_to(thumb);

      const unsigned int old_normalization = disp.normalization();
      bool old_is_resized = disp.is_resized();
      disp._normalization = 0;
      disp.show().set_key(0).set_wheel().show_mouse();

      static const unsigned char foreground_color[] = { 255,255,255 }, background_color[] = { 0,0,0 };
      int area = 0, area_started = 0, area_clicked = 0, phase = 0,
        X0 = (int)((XYZ?XYZ[0]:_width/2)%_width),
        Y0 = (int)((XYZ?XYZ[1]:_height/2)%_height),
        Z0 = (int)((XYZ?XYZ[2]:_depth/2)%_depth),
        X1 =-1, Y1 = -1, Z1 = -1,
        X3d = -1, Y3d = -1,
        oX3d = X3d, oY3d = -1,
        omx = -1, omy = -1;
      float X = -1, Y = -1, Z = -1;
      unsigned int key = 0, font_size = 32;

      bool is_deep_selection = is_deep_selection_default,
        shape_selected = false, text_down = false, visible_cursor = true;
      static CImg<floatT> pose3d;
      static bool is_view3d = false, is_axes = true;
      if (reset_view3d) { pose3d.assign(); is_view3d = false; }
      CImg<floatT> points3d, opacities3d, sel_opacities3d;
      CImgList<uintT> primitives3d, sel_primitives3d;
      CImgList<ucharT> colors3d, sel_colors3d;
      CImg<ucharT> visu, visu0, view3d;
      CImg<charT> text(1024); *text = 0;

      while (!key && !disp.is_closed() && !shape_selected) {

        // Handle mouse motion and selection.
        int
          mx = disp.mouse_x(),
          my = disp.mouse_y();

        const float
          mX = mx<0?-1.f:(float)mx*(width() + (depth()>1?depth():0))/disp.width(),
          mY = my<0?-1.f:(float)my*(height() + (depth()>1?depth():0))/disp.height();

        area = 0;
        if (mX>=0 && mY>=0 && mX<width() && mY<height())  { area = 1; X = mX; Y = mY; Z = (float)(phase?Z1:Z0); }
        if (mX>=0 && mX<width() && mY>=height()) { area = 2; X = mX; Z = mY - _height; Y = (float)(phase?Y1:Y0); }
        if (mY>=0 && mX>=width() && mY<height()) { area = 3; Y = mY; Z = mX - _width; X = (float)(phase?X1:X0); }
        if (mX>=width() && mY>=height()) area = 4;
        if (disp.button()) { if (!area_clicked) area_clicked = area; } else area_clicked = 0;

        CImg<charT> filename(1024);

        switch (key = disp.key()) {
#if cimg_OS!=2
        case cimg::keyCTRLRIGHT :
#endif
        case 0 : case cimg::keyCTRLLEFT : key = 0; break;
        case cimg::keyPAGEUP :
          if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { disp.set_wheel(1); key = 0; } break;
        case cimg::keyPAGEDOWN :
          if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { disp.set_wheel(-1); key = 0; } break;
        case cimg::keyX : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            is_axes = !is_axes; disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyD : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                     CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false).
              _is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false)._is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).resize(cimg_fitscreen(_width,_height,_depth),false)._is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.resize(disp.screen_width(),disp.screen_height(),false).toggle_fullscreen()._is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyV : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            is_view3d = !is_view3d; disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyS : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u."
#ifdef cimg_use_png
                            "png",
#else
                            "bmp",
#endif
                            snap_number++);
            } while (cimg::path_exists(filename));
            if (visu0) {
              (+visu0).__draw_text(" Saving snapshot...",font_size,(int)text_down).display(disp);
              visu0.save(filename);
              (+visu0).__draw_text(" Snapshot '%s' saved. ",font_size,(int)text_down,filename._data).display(disp);
            }
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyO : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            do {

#ifdef cimg_use_zlib
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimgz",snap_number++);
#else
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimg",snap_number++);
#endif
            } while (cimg::path_exists(filename));
            (+visu0).__draw_text(" Saving instance... ",font_size,(int)text_down).display(disp);
            save(filename);
            (+visu0).__draw_text(" Instance '%s' saved. ",font_size,(int)text_down,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        }

        switch (area) {

        case 0 : // When mouse is out of image range
          mx = my = -1; X = Y = Z = -1;
          break;

        case 1 : case 2 : case 3 : { // When mouse is over the XY,XZ or YZ projections
          const unsigned int but = disp.button();
          const bool b1 = (bool)(but&1), b2 = (bool)(but&2), b3 = (bool)(but&4);

          if (b1 && phase==1 && area_clicked==area) { // When selection has been started (1st step)
            if (_depth>1 && (X1!=(int)X || Y1!=(int)Y || Z1!=(int)Z)) visu0.assign();
            X1 = (int)X; Y1 = (int)Y; Z1 = (int)Z;
          }
          if (!b1 && phase==2 && area_clicked!=area) { // When selection is at 2nd step (for volumes)
            switch (area_started) {
            case 1 : if (Z1!=(int)Z) visu0.assign(); Z1 = (int)Z; break;
            case 2 : if (Y1!=(int)Y) visu0.assign(); Y1 = (int)Y; break;
            case 3 : if (X1!=(int)X) visu0.assign(); X1 = (int)X; break;
            }
          }
          if (b2 && area_clicked==area) { // When moving through the image/volume
            if (phase) {
              if (_depth>1 && (X1!=(int)X || Y1!=(int)Y || Z1!=(int)Z)) visu0.assign();
              X1 = (int)X; Y1 = (int)Y; Z1 = (int)Z;
            } else {
              if (_depth>1 && (X0!=(int)X || Y0!=(int)Y || Z0!=(int)Z)) visu0.assign();
              X0 = (int)X; Y0 = (int)Y; Z0 = (int)Z;
            }
          }
          if (b3) { // Reset selection
            X = (float)X0; Y = (float)Y0; Z = (float)Z0; phase = area = area_clicked = area_started = 0;
            visu0.assign();
          }
          if (disp.wheel()) { // When moving through the slices of the volume (with mouse wheel)
            if (_depth>1 && !disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT() &&
                !disp.is_keySHIFTLEFT() && !disp.is_keySHIFTRIGHT()) {
              switch (area) {
              case 1 :
                if (phase) Z = (float)(Z1+=disp.wheel()); else Z = (float)(Z0+=disp.wheel());
                visu0.assign(); break;
              case 2 :
                if (phase) Y = (float)(Y1+=disp.wheel()); else Y = (float)(Y0+=disp.wheel());
                visu0.assign(); break;
              case 3 :
                if (phase) X = (float)(X1+=disp.wheel()); else X = (float)(X0+=disp.wheel());
                visu0.assign(); break;
              }
              disp.set_wheel();
            } else key = ~0U;
          }

          if ((phase==0 && b1) ||
              (phase==1 && !b1) ||
              (phase==2 && b1)) switch (phase) { // Detect change of phase
            case 0 :
              if (area==area_clicked) {
                X0 = X1 = (int)X; Y0 = Y1 = (int)Y; Z0 = Z1 = (int)Z; area_started = area; ++phase;
              } break;
            case 1 :
              if (area==area_started) {
                X1 = (int)X; Y1 = (int)Y; Z1 = (int)Z; ++phase;
                if (_depth>1) {
                  if (disp.is_keyCTRLLEFT()) is_deep_selection = !is_deep_selection_default;
                  if (is_deep_selection) ++phase;
                }
              } else if (!b1) { X = (float)X0; Y = (float)Y0; Z = (float)Z0; phase = 0; visu0.assign(); }
              break;
            case 2 : ++phase; break;
            }
        } break;

        case 4 : // When mouse is over the 3D view
          if (is_view3d && points3d) {
            X3d = mx - width()*disp.width()/(width() + (depth()>1?depth():0));
            Y3d = my - height()*disp.height()/(height() + (depth()>1?depth():0));
            if (oX3d<0) { oX3d = X3d; oY3d = Y3d; }
            // Left + right buttons: reset.
            if ((disp.button()&3)==3) { pose3d.assign(); view3d.assign(); oX3d = oY3d = X3d = Y3d = -1; }
            else if (disp.button()&1 && pose3d && (oX3d!=X3d || oY3d!=Y3d)) { // Left button: rotate
              const float
                R = 0.45f*std::min(view3d._width,view3d._height),
                R2 = R*R,
                u0 = (float)(oX3d - view3d.width()/2),
                v0 = (float)(oY3d - view3d.height()/2),
                u1 = (float)(X3d - view3d.width()/2),
                v1 = (float)(Y3d - view3d.height()/2),
                n0 = cimg::hypot(u0,v0),
                n1 = cimg::hypot(u1,v1),
                nu0 = n0>R?(u0*R/n0):u0,
                nv0 = n0>R?(v0*R/n0):v0,
                nw0 = (float)std::sqrt(std::max(0.f,R2 - nu0*nu0 - nv0*nv0)),
                nu1 = n1>R?(u1*R/n1):u1,
                nv1 = n1>R?(v1*R/n1):v1,
                nw1 = (float)std::sqrt(std::max(0.f,R2 - nu1*nu1 - nv1*nv1)),
                u = nv0*nw1 - nw0*nv1,
                v = nw0*nu1 - nu0*nw1,
                w = nv0*nu1 - nu0*nv1,
                n = cimg::hypot(u,v,w),
                alpha = (float)std::asin(n/R2)*180/cimg::PI;
              pose3d.draw_image(CImg<floatT>::rotation_matrix(u,v,w,-alpha)*pose3d.get_crop(0,0,2,2));
              view3d.assign();
            } else if (disp.button()&2 && pose3d && oY3d!=Y3d) { // Right button: zoom
              pose3d(3,2)+=(Y3d - oY3d)*1.5f; view3d.assign();
            }
            if (disp.wheel()) { // Wheel: zoom
              pose3d(3,2)-=disp.wheel()*15; view3d.assign(); disp.set_wheel();
            }
            if (disp.button()&4 && pose3d && (oX3d!=X3d || oY3d!=Y3d)) { // Middle button: shift
              pose3d(3,0)-=oX3d - X3d; pose3d(3,1)-=oY3d - Y3d; view3d.assign();
            }
            oX3d = X3d; oY3d = Y3d;
          }
          mx = my = -1; X = Y = Z = -1;
          break;
        }

        if (phase) {
          if (!feature_type) shape_selected = phase?true:false;
          else {
            if (_depth>1) shape_selected = (phase==3)?true:false;
            else shape_selected = (phase==2)?true:false;
          }
        }

        if (X0<0) X0 = 0;
        if (X0>=width()) X0 = width() - 1;
        if (Y0<0) Y0 = 0;
        if (Y0>=height()) Y0 = height() - 1;
        if (Z0<0) Z0 = 0;
        if (Z0>=depth()) Z0 = depth() - 1;
        if (X1<1) X1 = 0;
        if (X1>=width()) X1 = width() - 1;
        if (Y1<0) Y1 = 0;
        if (Y1>=height()) Y1 = height() - 1;
        if (Z1<0) Z1 = 0;
        if (Z1>=depth()) Z1 = depth() - 1;

        // Draw visualization image on the display.
        if (mx!=omx || my!=omy || !visu0 || (_depth>1 && !view3d)) {

          if (!visu0) { // Create image of projected planes
            if (thumb) thumb._get_select(disp,old_normalization,phase?X1:X0,phase?Y1:Y0,phase?Z1:Z0).move_to(visu0);
            else _get_select(disp,old_normalization,phase?X1:X0,phase?Y1:Y0,phase?Z1:Z0).move_to(visu0);
            visu0.resize(disp);
            view3d.assign();
            points3d.assign();
          }

          if (is_view3d && _depth>1 && !view3d) { // Create 3D view for volumetric images
            const unsigned int
              _x3d = (unsigned int)cimg::round((float)_width*visu0._width/(_width + _depth),1,1),
              _y3d = (unsigned int)cimg::round((float)_height*visu0._height/(_height + _depth),1,1),
              x3d = _x3d>=visu0._width?visu0._width - 1:_x3d,
              y3d = _y3d>=visu0._height?visu0._height - 1:_y3d;
            CImg<ucharT>(1,2,1,1,64,128).resize(visu0._width - x3d,visu0._height - y3d,1,visu0._spectrum,3).
              move_to(view3d);
            if (!points3d) {
              get_projections3d(primitives3d,colors3d,phase?X1:X0,phase?Y1:Y0,phase?Z1:Z0,true).move_to(points3d);
              points3d.append(CImg<floatT>(8,3,1,1,
                                           0,_width - 1,_width - 1,0,0,_width - 1,_width - 1,0,
                                           0,0,_height - 1,_height - 1,0,0,_height - 1,_height - 1,
                                           0,0,0,0,_depth - 1,_depth - 1,_depth - 1,_depth - 1),'x');
              CImg<uintT>::vector(12,13).move_to(primitives3d); CImg<uintT>::vector(13,14).move_to(primitives3d);
              CImg<uintT>::vector(14,15).move_to(primitives3d); CImg<uintT>::vector(15,12).move_to(primitives3d);
              CImg<uintT>::vector(16,17).move_to(primitives3d); CImg<uintT>::vector(17,18).move_to(primitives3d);
              CImg<uintT>::vector(18,19).move_to(primitives3d); CImg<uintT>::vector(19,16).move_to(primitives3d);
              CImg<uintT>::vector(12,16).move_to(primitives3d); CImg<uintT>::vector(13,17).move_to(primitives3d);
              CImg<uintT>::vector(14,18).move_to(primitives3d); CImg<uintT>::vector(15,19).move_to(primitives3d);
              colors3d.insert(12,CImg<ucharT>::vector(255,255,255));
              opacities3d.assign(primitives3d.width(),1,1,1,0.5f);
              if (!phase) {
                opacities3d[0] = opacities3d[1] = opacities3d[2] = 0.8f;
                sel_primitives3d.assign();
                sel_colors3d.assign();
                sel_opacities3d.assign();
              } else {
                if (feature_type==2) {
                  points3d.append(CImg<floatT>(8,3,1,1,
                                               X0,X1,X1,X0,X0,X1,X1,X0,
                                               Y0,Y0,Y1,Y1,Y0,Y0,Y1,Y1,
                                               Z0,Z0,Z0,Z0,Z1,Z1,Z1,Z1),'x');
                  sel_primitives3d.assign();
                  CImg<uintT>::vector(20,21).move_to(sel_primitives3d);
                  CImg<uintT>::vector(21,22).move_to(sel_primitives3d);
                  CImg<uintT>::vector(22,23).move_to(sel_primitives3d);
                  CImg<uintT>::vector(23,20).move_to(sel_primitives3d);
                  CImg<uintT>::vector(24,25).move_to(sel_primitives3d);
                  CImg<uintT>::vector(25,26).move_to(sel_primitives3d);
                  CImg<uintT>::vector(26,27).move_to(sel_primitives3d);
                  CImg<uintT>::vector(27,24).move_to(sel_primitives3d);
                  CImg<uintT>::vector(20,24).move_to(sel_primitives3d);
                  CImg<uintT>::vector(21,25).move_to(sel_primitives3d);
                  CImg<uintT>::vector(22,26).move_to(sel_primitives3d);
                  CImg<uintT>::vector(23,27).move_to(sel_primitives3d);
                } else {
                  points3d.append(CImg<floatT>(2,3,1,1,
                                               X0,X1,
                                               Y0,Y1,
                                               Z0,Z1),'x');
                  sel_primitives3d.assign(CImg<uintT>::vector(20,21));
                }
                sel_colors3d.assign(sel_primitives3d._width,CImg<ucharT>::vector(255,255,255));
                sel_opacities3d.assign(sel_primitives3d._width,1,1,1,0.8f);
              }
              points3d.shift_object3d(-0.5f*(_width - 1),-0.5f*(_height - 1),-0.5f*(_depth - 1)).resize_object3d();
              points3d*=0.75f*std::min(view3d._width,view3d._height);
            }

            if (!pose3d) CImg<floatT>(4,3,1,1, 1,0,0,0, 0,1,0,0, 0,0,1,0).move_to(pose3d);
            CImg<floatT> zbuffer3d(view3d._width,view3d._height,1,1,0);
            const CImg<floatT> rotated_points3d = pose3d.get_crop(0,0,2,2)*points3d;
            if (sel_primitives3d)
              view3d.draw_object3d(pose3d(3,0) + 0.5f*view3d._width,
                                   pose3d(3,1) + 0.5f*view3d._height,
                                   pose3d(3,2),
                                   rotated_points3d,sel_primitives3d,sel_colors3d,sel_opacities3d,
                                   2,true,500,0,0,0,0,0,1,zbuffer3d);
            view3d.draw_object3d(pose3d(3,0) + 0.5f*view3d._width,
                                 pose3d(3,1) + 0.5f*view3d._height,
                                 pose3d(3,2),
                                 rotated_points3d,primitives3d,colors3d,opacities3d,
                                 2,true,500,0,0,0,0,0,1,zbuffer3d);
            visu0.draw_image(x3d,y3d,view3d);
          }
          visu = visu0;

          if (X<0 || Y<0 || Z<0) { if (!visible_cursor) { disp.show_mouse(); visible_cursor = true; }}
          else {
            if (is_axes) { if (visible_cursor) { disp.hide_mouse(); visible_cursor = false; }}
            else { if (!visible_cursor) { disp.show_mouse(); visible_cursor = true; }}
            const int d = (depth()>1)?depth():0;
            int _vX = (int)X, _vY = (int)Y, _vZ = (int)Z;
            if (phase>=2) { _vX = X1; _vY = Y1; _vZ = Z1; }
            int
              w = disp.width(), W = width() + d,
              h = disp.height(), H = height() + d,
              _xp = (int)(_vX*(float)w/W), xp = _xp + ((int)(_xp*(float)W/w)!=_vX),
              _yp = (int)(_vY*(float)h/H), yp = _yp + ((int)(_yp*(float)H/h)!=_vY),
              _xn = (int)((_vX + 1.f)*w/W - 1), xn = _xn + ((int)((_xn + 1.f)*W/w)!=_vX + 1),
              _yn = (int)((_vY + 1.f)*h/H - 1), yn = _yn + ((int)((_yn + 1.f)*H/h)!=_vY + 1),
              _zxp = (int)((_vZ + width())*(float)w/W), zxp = _zxp + ((int)(_zxp*(float)W/w)!=_vZ + width()),
              _zyp = (int)((_vZ + height())*(float)h/H), zyp = _zyp + ((int)(_zyp*(float)H/h)!=_vZ + height()),
              _zxn = (int)((_vZ + width() + 1.f)*w/W - 1),
                       zxn = _zxn + ((int)((_zxn + 1.f)*W/w)!=_vZ + width() + 1),
              _zyn = (int)((_vZ + height() + 1.f)*h/H - 1),
                       zyn = _zyn + ((int)((_zyn + 1.f)*H/h)!=_vZ + height() + 1),
              _xM = (int)(width()*(float)w/W - 1), xM = _xM + ((int)((_xM + 1.f)*W/w)!=width()),
              _yM = (int)(height()*(float)h/H - 1), yM = _yM + ((int)((_yM + 1.f)*H/h)!=height()),
              xc = (xp + xn)/2,
              yc = (yp + yn)/2,
              zxc = (zxp + zxn)/2,
              zyc = (zyp + zyn)/2,
              xf = (int)(X*w/W),
              yf = (int)(Y*h/H),
              zxf = (int)((Z + width())*w/W),
              zyf = (int)((Z + height())*h/H);

            if (is_axes) { // Draw axes
              visu.draw_line(0,yf,visu.width() - 1,yf,foreground_color,0.7f,0xFF00FF00).
                draw_line(0,yf,visu.width() - 1,yf,background_color,0.7f,0x00FF00FF).
                draw_line(xf,0,xf,visu.height() - 1,foreground_color,0.7f,0xFF00FF00).
                draw_line(xf,0,xf,visu.height() - 1,background_color,0.7f,0x00FF00FF);
              if (_depth>1)
                visu.draw_line(zxf,0,zxf,yM,foreground_color,0.7f,0xFF00FF00).
                  draw_line(zxf,0,zxf,yM,background_color,0.7f,0x00FF00FF).
                  draw_line(0,zyf,xM,zyf,foreground_color,0.7f,0xFF00FF00).
                  draw_line(0,zyf,xM,zyf,background_color,0.7f,0x00FF00FF);
            }

            // Draw box cursor.
            if (xn - xp>=4 && yn - yp>=4)
              visu.draw_rectangle(xp,yp,xn,yn,foreground_color,0.2f).
                draw_rectangle(xp,yp,xn,yn,foreground_color,1,0xAAAAAAAA).
                draw_rectangle(xp,yp,xn,yn,background_color,1,0x55555555);
            if (_depth>1) {
              if (yn - yp>=4 && zxn - zxp>=4)
                visu.draw_rectangle(zxp,yp,zxn,yn,background_color,0.2f).
                                              draw_rectangle(zxp,yp,zxn,yn,foreground_color,1,0xAAAAAAAA).
                                              draw_rectangle(zxp,yp,zxn,yn,background_color,1,0x55555555);
              if (xn - xp>=4 && zyn - zyp>=4)
                visu.draw_rectangle(xp,zyp,xn,zyn,background_color,0.2f).
                          draw_rectangle(xp,zyp,xn,zyn,foreground_color,1,0xAAAAAAAA).
                          draw_rectangle(xp,zyp,xn,zyn,background_color,1,0x55555555);
            }

            // Draw selection.
            if (phase && (phase!=1 || area_started==area)) {
              const int
                _xp0 = (int)(X0*(float)w/W), xp0 = _xp0 + ((int)(_xp0*(float)W/w)!=X0),
                _yp0 = (int)(Y0*(float)h/H), yp0 = _yp0 + ((int)(_yp0*(float)H/h)!=Y0),
                _xn0 = (int)((X0 + 1.f)*w/W - 1), xn0 = _xn0 + ((int)((_xn0 + 1.f)*W/w)!=X0 + 1),
                _yn0 = (int)((Y0 + 1.f)*h/H - 1), yn0 = _yn0 + ((int)((_yn0 + 1.f)*H/h)!=Y0 + 1),
                _zxp0 = (int)((Z0 + width())*(float)w/W), zxp0 = _zxp0 + ((int)(_zxp0*(float)W/w)!=Z0 + width()),
                _zyp0 = (int)((Z0 + height())*(float)h/H), zyp0 = _zyp0 + ((int)(_zyp0*(float)H/h)!=Z0 + height()),
                _zxn0 = (int)((Z0 + width() + 1.f)*w/W - 1),
                zxn0 = _zxn0 + ((int)((_zxn0 + 1.f)*W/w)!=Z0 + width() + 1),
                _zyn0 = (int)((Z0 + height() + 1.f)*h/H - 1),
                zyn0 = _zyn0 + ((int)((_zyn0 + 1.f)*H/h)!=Z0 + height() + 1),
                xc0 = (xp0 + xn0)/2,
                yc0 = (yp0 + yn0)/2,
                zxc0 = (zxp0 + zxn0)/2,
                zyc0 = (zyp0 + zyn0)/2;

              switch (feature_type) {
              case 1 : { // Vector
                visu.draw_arrow(xc0,yc0,xc,yc,background_color,0.9f,30,5,0x33333333).
                  draw_arrow(xc0,yc0,xc,yc,foreground_color,0.9f,30,5,0xCCCCCCCC);
                if (d) {
                  visu.draw_arrow(zxc0,yc0,zxc,yc,background_color,0.9f,30,5,0x33333333).
                    draw_arrow(zxc0,yc0,zxc,yc,foreground_color,0.9f,30,5,0xCCCCCCCC).
                    draw_arrow(xc0,zyc0,xc,zyc,background_color,0.9f,30,5,0x33333333).
                    draw_arrow(xc0,zyc0,xc,zyc,foreground_color,0.9f,30,5,0xCCCCCCCC);
                }
              } break;
              case 2 : { // Box
                visu.draw_rectangle(X0<X1?xp0:xp,Y0<Y1?yp0:yp,X0<X1?xn:xn0,Y0<Y1?yn:yn0,background_color,0.2f).
                  draw_rectangle(X0<X1?xp0:xp,Y0<Y1?yp0:yp,X0<X1?xn:xn0,Y0<Y1?yn:yn0,background_color,0.9f,0x55555555).
                  draw_rectangle(X0<X1?xp0:xp,Y0<Y1?yp0:yp,X0<X1?xn:xn0,Y0<Y1?yn:yn0,foreground_color,0.9f,0xAAAAAAAA);
                if (xc0!=xc && yc0!=yc)
                  visu.draw_line(xc0,yc0,xc,yc,background_color,0.9f,0x33333333).
                    draw_line(xc0,yc0,xc,yc,foreground_color,0.9f,0xCCCCCCCC);
                if (d) {
                  visu.draw_rectangle(Z0<Z1?zxp0:zxp,Y0<Y1?yp0:yp,Z0<Z1?zxn:zxn0,Y0<Y1?yn:yn0,background_color,0.2f).
                    draw_rectangle(Z0<Z1?zxp0:zxp,Y0<Y1?yp0:yp,Z0<Z1?zxn:zxn0,Y0<Y1?yn:yn0,
                                   background_color,0.9f,0x55555555).
                    draw_rectangle(Z0<Z1?zxp0:zxp,Y0<Y1?yp0:yp,Z0<Z1?zxn:zxn0,Y0<Y1?yn:yn0,
                                   foreground_color,0.9f,0xAAAAAAAA);
                  if (zxc0!=zxc && yc0!=yc)
                    visu.draw_line(zxc0,yc0,zxc,yc,background_color,0.9f,0x33333333).
                      draw_line(zxc0,yc0,zxc,yc,foreground_color,0.9f,0xCCCCCCCC);
                  visu.draw_rectangle(X0<X1?xp0:xp,Z0<Z1?zyp0:zyp,X0<X1?xn:xn0,Z0<Z1?zyn:zyn0,
                                      background_color,0.2f).
                    draw_rectangle(X0<X1?xp0:xp,Z0<Z1?zyp0:zyp,X0<X1?xn:xn0,Z0<Z1?zyn:zyn0,
                                   background_color,0.9f,0x55555555).
                    draw_rectangle(X0<X1?xp0:xp,Z0<Z1?zyp0:zyp,X0<X1?xn:xn0,Z0<Z1?zyn:zyn0,
                                   foreground_color,0.9f,0xAAAAAAAA);
                  if (xp0!=xn && zyp0!=zyn)
                    visu.draw_line(xp0,zyp0,xn,zyn,background_color,0.9f,0x33333333).
                      draw_line(xp0,zyp0,xn,zyn,foreground_color,0.9f,0xCCCCCCCC);
                }
              } break;
              case 3 : { // Ellipse
                visu.draw_ellipse(xc0,yc0,
                                  (float)cimg::abs(xc - xc0),
                                  (float)cimg::abs(yc - yc0),0,background_color,0.2f).
                  draw_ellipse(xc0,yc0,
                               (float)cimg::abs(xc - xc0),
                               (float)cimg::abs(yc - yc0),0,foreground_color,0.9f,~0U).
                  draw_point(xc0,yc0,foreground_color,0.9f);
                if (d) {
                  visu.draw_ellipse(zxc0,yc0,(float)cimg::abs(zxc - zxc0),(float)cimg::abs(yc - yc0),0,
                                    background_color,0.2f).
                    draw_ellipse(zxc0,yc0,(float)cimg::abs(zxc - zxc0),(float)cimg::abs(yc - yc0),0,
                                 foreground_color,0.9f,~0U).
                    draw_point(zxc0,yc0,foreground_color,0.9f).
                    draw_ellipse(xc0,zyc0,(float)cimg::abs(xc - xc0),(float)cimg::abs(zyc - zyc0),0,
                                 background_color,0.2f).
                    draw_ellipse(xc0,zyc0,(float)cimg::abs(xc - xc0),(float)cimg::abs(zyc - zyc0),0,
                                 foreground_color,0.9f,~0U).
                    draw_point(xc0,zyc0,foreground_color,0.9f);
                }
              } break;
              }
            }

            // Draw text info.
            if (my>=0 && my<13) text_down = true; else if (my>=visu.height() - 13) text_down = false;
            if (!feature_type || !phase) {
              if (X>=0 && Y>=0 && Z>=0 && X<width() && Y<height() && Z<depth()) {
                if (_depth>1 || force_display_z_coord)
                  cimg_snprintf(text,text._width," Point (%d,%d,%d) = [ ",origX + (int)X,origY + (int)Y,origZ + (int)Z);
                else cimg_snprintf(text,text._width," Point (%d,%d) = [ ",origX + (int)X,origY + (int)Y);
                CImg<T> values = get_vector_at((int)X,(int)Y,(int)Z);
                const bool is_large_spectrum = values._height>8;
                if (is_large_spectrum)
                  values.draw_image(0,4,values.get_rows(values._height - 4,values._height - 1)).resize(1,8,1,1,0);
                char *ctext = text._data + std::strlen(text), *const ltext = text._data + 512;
                for (unsigned int c = 0; c<values._height && ctext<ltext; ++c) {
                  cimg_snprintf(ctext,24,cimg::type<T>::format_s(),
                                cimg::type<T>::format(values[c]));
                  ctext += std::strlen(ctext);
                  if (c==3 && is_large_spectrum) {
                    cimg_snprintf(ctext,24," ...");
                    ctext += std::strlen(ctext);
                  }
                  *(ctext++) = ' '; *ctext = 0;
                }
                std::strcpy(text._data + std::strlen(text),"] ");
              }
            } else switch (feature_type) {
              case 1 : {
                const double dX = (double)(X0 - X1), dY = (double)(Y0 - Y1), dZ = (double)(Z0 - Z1),
                  length = cimg::round(cimg::hypot(dX,dY,dZ),0.1);
                if (_depth>1 || force_display_z_coord)
                  cimg_snprintf(text,text._width," Vect (%d,%d,%d)-(%d,%d,%d), Length = %g ",
                                origX + X0,origY + Y0,origZ + Z0,origX + X1,origY + Y1,origZ + Z1,length);
                else if (_width!=1 && _height!=1)
                  cimg_snprintf(text,text._width," Vect (%d,%d)-(%d,%d), Length = %g, Angle = %g\260 ",
                                origX + X0,origY + Y0,origX + X1,origY + Y1,length,
                                cimg::round(cimg::mod(180*std::atan2(-dY,-dX)/cimg::PI,360.),0.1));
                else
                  cimg_snprintf(text,text._width," Vect (%d,%d)-(%d,%d), Length = %g ",
                                origX + X0,origY + Y0,origX + X1,origY + Y1,length);
              } break;
              case 2 : {
                const double dX = (double)(X0 - X1), dY = (double)(Y0 - Y1), dZ = (double)(Z0 - Z1),
                  length = cimg::round(cimg::hypot(dX,dY,dZ),0.1);
                if (_depth>1 || force_display_z_coord)
                  cimg_snprintf(text,text._width,
                                " Box ( %d,%d,%d ) - ( %d,%d,%d )\n Size = ( %d,%d,%d ), Length = %g ",
                                origX + (X0<X1?X0:X1),origY + (Y0<Y1?Y0:Y1),origZ + (Z0<Z1?Z0:Z1),
                                origX + (X0<X1?X1:X0),origY + (Y0<Y1?Y1:Y0),origZ + (Z0<Z1?Z1:Z0),
                                1 + cimg::abs(X0 - X1),1 + cimg::abs(Y0 - Y1),1 + cimg::abs(Z0 - Z1),length);
                else if (_width!=1 && _height!=1)
                  cimg_snprintf(text,text._width,
                                " Box ( %d,%d ) - ( %d,%d )\n Size = ( %d,%d ), Length = %g \n Angle = %g\260 ",
                                origX + (X0<X1?X0:X1),origY + (Y0<Y1?Y0:Y1),
                                origX + (X0<X1?X1:X0),origY + (Y0<Y1?Y1:Y0),
                                1 + cimg::abs(X0 - X1),1 + cimg::abs(Y0 - Y1),length,
                                cimg::round(cimg::mod(180*std::atan2(-dY,-dX)/cimg::PI,360.),0.1));
                else
                  cimg_snprintf(text,text._width,
                                " Box ( %d,%d ) - ( %d,%d )\n Size = (%d,%d), Length = %g ",
                                origX + (X0<X1?X0:X1),origY + (Y0<Y1?Y0:Y1),
                                origX + (X0<X1?X1:X0),origY + (Y0<Y1?Y1:Y0),
                                1 + cimg::abs(X0 - X1),1 + cimg::abs(Y0 - Y1),length);
              } break;
              default :
                if (_depth>1 || force_display_z_coord)
                  cimg_snprintf(text,text._width," Ellipse ( %d,%d,%d ) - ( %d,%d,%d ), Radii = ( %d,%d,%d ) ",
                                origX + X0,origY + Y0,origZ + Z0,origX + X1,origY + Y1,origZ + Z1,
                                1 + cimg::abs(X0 - X1),1 + cimg::abs(Y0 - Y1),1 + cimg::abs(Z0 - Z1));
                else cimg_snprintf(text,text._width," Ellipse ( %d,%d ) - ( %d,%d ), Radii = ( %d,%d ) ",
                                   origX + X0,origY + Y0,origX + X1,origY + Y1,
                                   1 + cimg::abs(X0 - X1),1 + cimg::abs(Y0 - Y1));
              }
            if (phase || (mx>=0 && my>=0)) visu.__draw_text("%s",font_size,(int)text_down,text._data);
          }

          disp.display(visu);
        }
        if (!shape_selected) disp.wait();
        if (disp.is_resized()) { disp.resize(false)._is_resized = false; old_is_resized = true; visu0.assign(); }
        omx = mx; omy = my;
        if (!exit_on_anykey && key && key!=cimg::keyESC &&
            (key!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          key = 0;
        }
      }

      // Return result.
      CImg<intT> res(1,feature_type==0?3:6,1,1,-1);
      if (XYZ) { XYZ[0] = (unsigned int)X0; XYZ[1] = (unsigned int)Y0; XYZ[2] = (unsigned int)Z0; }
      if (shape_selected) {
        if (feature_type==2) {
          if (is_deep_selection) switch (area_started) {
            case 1 : Z0 = 0; Z1 = _depth - 1; break;
            case 2 : Y0 = 0; Y1 = _height - 1; break;
            case 3 : X0 = 0; X1 = _width - 1; break;
          }
          if (X0>X1) cimg::swap(X0,X1);
          if (Y0>Y1) cimg::swap(Y0,Y1);
          if (Z0>Z1) cimg::swap(Z0,Z1);
        }
        if (X1<0 || Y1<0 || Z1<0) X0 = Y0 = Z0 = X1 = Y1 = Z1 = -1;
        switch (feature_type) {
        case 1 : case 2 : res[0] = X0; res[1] = Y0; res[2] = Z0; res[3] = X1; res[4] = Y1; res[5] = Z1; break;
        case 3 :
          res[3] = cimg::abs(X1 - X0); res[4] = cimg::abs(Y1 - Y0); res[5] = cimg::abs(Z1 - Z0);
          res[0] = X0; res[1] = Y0; res[2] = Z0;
          break;
        default : res[0] = X0; res[1] = Y0; res[2] = Z0;
        }
      }
      if (!exit_on_anykey || !(disp.button()&4)) disp.set_button();
      if (!visible_cursor) disp.show_mouse();
      disp._normalization = old_normalization;
      disp._is_resized = old_is_resized;
      if (key!=~0U) disp.set_key(key);
      return res;
    }

    // Return a visualizable 8-bit unsigned char image for display routines.
    CImg<ucharT> _get_select(const CImgDisplay& disp, const int normalization,
                             const int x, const int y, const int z) const {
      if (is_empty()) return CImg<ucharT>(1,1,1,1,0);
      const CImg<T> crop = get_shared_channels(0,std::min(2,spectrum() - 1));
      CImg<Tuchar> img2d;
      if (_depth>1) {
        const int mdisp = std::min(disp.screen_width(),disp.screen_height());
        if (depth()>mdisp) {
          crop.get_resize(-100,-100,mdisp,-100,0).move_to(img2d);
          img2d.projections2d(x,y,z*img2d._depth/_depth);
        } else crop.get_projections2d(x,y,z).move_to(img2d);
      } else CImg<Tuchar>(crop,false).move_to(img2d);

      // Check for inf and NaN values.
      if (cimg::type<T>::is_float() && normalization) {
        bool is_inf = false, is_nan = false;
        cimg_for(img2d,ptr,Tuchar)
          if (cimg::type<T>::is_inf(*ptr)) { is_inf = true; break; }
          else if (cimg::type<T>::is_nan(*ptr)) { is_nan = true; break; }
        if (is_inf || is_nan) {
          Tint m0 = (Tint)cimg::type<T>::max(), M0 = (Tint)cimg::type<T>::min();
          if (!normalization) { m0 = 0; M0 = 255; }
          else if (normalization==2) { m0 = (Tint)disp._min; M0 = (Tint)disp._max; }
          else {
            cimg_for(img2d,ptr,Tuchar)
              if (!cimg::type<T>::is_inf(*ptr) && !cimg::type<T>::is_nan(*ptr)) {
                if (*ptr<(Tuchar)m0) m0 = *ptr;
                if (*ptr>(Tuchar)M0) M0 = *ptr;
              }
          }
          const T
            val_minf = (T)(normalization==1 || normalization==3?m0 - cimg::abs(m0):m0),
            val_pinf = (T)(normalization==1 || normalization==3?M0 + cimg::abs(M0):M0);
          if (is_nan)
            cimg_for(img2d,ptr,Tuchar)
              if (cimg::type<T>::is_nan(*ptr)) *ptr = val_minf; // Replace NaN values
          if (is_inf)
            cimg_for(img2d,ptr,Tuchar)
              if (cimg::type<T>::is_inf(*ptr)) *ptr = (float)*ptr<0?val_minf:val_pinf; // Replace +-inf values
        }
      }

      switch (normalization) {
      case 1 : img2d.normalize((ucharT)0,(ucharT)255); break;
      case 2 : {
        const float m = disp._min, M = disp._max;
        (img2d-=m)*=255.f/(M - m>0?M - m:1);
      } break;
      case 3 :
        if (cimg::type<T>::is_float()) img2d.normalize((ucharT)0,(ucharT)255);
        else {
          const float
            m = (float)cimg::type<T>::min(),
            M = (float)cimg::type<T>::max();
          (img2d-=m)*=255.f/(M - m>0?M - m:1);
        } break;
      }
      if (img2d.spectrum()==2) img2d.channels(0,2);
      return img2d;
    }

    //! Select a sub-graph within a graph.
    CImg<intT> get_select_graph(CImgDisplay &disp,
                                const unsigned int plot_type=1, const unsigned int vertex_type=1,
                                const char *const labelx=0, const double xmin=0, const double xmax=0,
                                const char *const labely=0, const double ymin=0, const double ymax=0,
                                const bool exit_on_anykey=false) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "select_graph(): Empty instance.",
                                    cimg_instance);
      if (!disp) disp.assign(cimg_fitscreen(CImgDisplay::screen_width()/2,CImgDisplay::screen_height()/2,1),0,0).
                   set_title("CImg<%s>",pixel_type());
      const ulongT siz = (ulongT)_width*_height*_depth;
      const unsigned int old_normalization = disp.normalization();
      disp.show().set_button().set_wheel()._normalization = 0;

      double nymin = ymin, nymax = ymax, nxmin = xmin, nxmax = xmax;
      if (nymin==nymax) { nymin = (Tfloat)min_max(nymax); const double dy = nymax - nymin; nymin-=dy/20; nymax+=dy/20; }
      if (nymin==nymax) { --nymin; ++nymax; }
      if (nxmin==nxmax && nxmin==0) { nxmin = 0; nxmax = siz - 1.; }

      static const unsigned char black[] = { 0, 0, 0 }, white[] = { 255, 255, 255 }, gray[] = { 220, 220, 220 };
      static const unsigned char gray2[] = { 110, 110, 110 }, ngray[] = { 35, 35, 35 };

      CImg<ucharT> colormap(3,_spectrum);
      if (_spectrum==1) { colormap[0] = colormap[1] = 120; colormap[2] = 200; }
      else {
        colormap(0,0) = 220; colormap(1,0) = 10; colormap(2,0) = 10;
        if (_spectrum>1) { colormap(0,1) = 10;  colormap(1,1) = 220; colormap(2,1) = 10;  }
        if (_spectrum>2) { colormap(0,2) = 10;  colormap(1,2) = 10;  colormap(2,2) = 220; }
        if (_spectrum>3) { colormap(0,3) = 220; colormap(1,3) = 220; colormap(2,3) = 10;  }
        if (_spectrum>4) { colormap(0,4) = 220; colormap(1,4) = 10;  colormap(2,4) = 220; }
        if (_spectrum>5) { colormap(0,5) = 10;  colormap(1,5) = 220; colormap(2,5) = 220; }
        if (_spectrum>6) {
          cimg_uint64 rng = 10;
          cimg_for_inY(colormap,6,colormap.height()-1,k) {
            colormap(0,k) = (unsigned char)(120 + cimg::rand(-100.f,100.f,&rng));
            colormap(1,k) = (unsigned char)(120 + cimg::rand(-100.f,100.f,&rng));
            colormap(2,k) = (unsigned char)(120 + cimg::rand(-100.f,100.f,&rng));
          }
        }
      }

      CImg<ucharT> visu0, visu, graph, text, axes;
      int x0 = -1, x1 = -1, y0 = -1, y1 = -1, omouse_x = -2, omouse_y = -2;
      const unsigned int one = plot_type==3?0U:1U;
      unsigned int okey = 0, obutton = 0, font_size = 32;
      CImg<charT> message(1024);
      CImg_3x3(I,unsigned char);

      for (bool selected = false; !selected && !disp.is_closed() && !okey && !disp.wheel(); ) {
        const int mouse_x = disp.mouse_x(), mouse_y = disp.mouse_y();
        const unsigned int key = disp.key(), button = disp.button();

        // Generate graph representation.
        if (!visu0) {
          visu0.assign(disp.width(),disp.height(),1,3,220);
          const int gdimx = disp.width() - 32, gdimy = disp.height() - 32;
          if (gdimx>0 && gdimy>0) {
            graph.assign(gdimx,gdimy,1,3,255);
            if (siz<32) {
              if (siz>1) graph.draw_grid(gdimx/(float)(siz - one),gdimy/(float)(siz - one),0,0,
                                         false,true,black,0.2f,0x33333333,0x33333333);
            } else graph.draw_grid(-10,-10,0,0,false,true,black,0.2f,0x33333333,0x33333333);
            cimg_forC(*this,c)
              graph.draw_graph(get_shared_channel(c),&colormap(0,c),(plot_type!=3 || _spectrum==1)?1:0.6f,
                               plot_type,vertex_type,nymax,nymin);

            axes.assign(gdimx,gdimy,1,1,0);
            const float
              dx = (float)cimg::abs(nxmax - nxmin), dy = (float)cimg::abs(nymax - nymin),
              px = (float)std::pow(10.,(int)std::log10(dx?dx:1) - 2.),
              py = (float)std::pow(10.,(int)std::log10(dy?dy:1) - 2.);
            const CImg<Tdouble>
              seqx = dx<=0?CImg<Tdouble>::vector(nxmin):
                CImg<Tdouble>::sequence(1 + gdimx/60,nxmin,one?nxmax:nxmin + (nxmax - nxmin)*(siz + 1)/siz),
              seqy = CImg<Tdouble>::sequence(1 + gdimy/60,nymax,nymin);

            const bool allow_zero = (nxmin*nxmax>0) || (nymin*nymax>0);
            axes.draw_axes(seqx,seqy,white,1,~0U,~0U,13,allow_zero,px,py);
            if (nymin>0) axes.draw_axis(seqx,gdimy - 1,gray,1,~0U,13,allow_zero,px);
            if (nymax<0) axes.draw_axis(seqx,0,gray,1,~0U,13,allow_zero,px);
            if (nxmin>0) axes.draw_axis(0,seqy,gray,1,~0U,13,allow_zero,py);
            if (nxmax<0) axes.draw_axis(gdimx - 1,seqy,gray,1,~0U,13,allow_zero,py);

            cimg_for3x3(axes,x,y,0,0,I,unsigned char)
              if (Icc) {
                if (Icc==255) cimg_forC(graph,c) graph(x,y,c) = 0;
                else cimg_forC(graph,c) graph(x,y,c) = (unsigned char)(2*graph(x,y,c)/3);
              }
              else if (Ipc || Inc || Icp || Icn || Ipp || Inn || Ipn || Inp)
                cimg_forC(graph,c) graph(x,y,c) = (unsigned char)((graph(x,y,c) + 511)/3);

            visu0.draw_image(16,16,graph);
            visu0.draw_line(15,15,16 + gdimx,15,gray2).draw_line(16 + gdimx,15,16 + gdimx,16 + gdimy,gray2).
              draw_line(16 + gdimx,16 + gdimy,15,16 + gdimy,white).draw_line(15,16 + gdimy,15,15,white);
          } else graph.assign();
          text.assign().draw_text(0,0,labelx?labelx:"X-axis",white,ngray,1,13).resize(-100,-100,1,3);
          visu0.draw_image((visu0.width() - text.width())/2,visu0.height() - 14,~text);
          text.assign().draw_text(0,0,labely?labely:"Y-axis",white,ngray,1,13).rotate(-90).resize(-100,-100,1,3);
          visu0.draw_image(1,(visu0.height() - text.height())/2,~text);
          visu.assign();
        }

        // Generate and display current view.
        if (!visu) {
          visu.assign(visu0);
          if (graph && x0>=0 && x1>=0) {
            const int
              nx0 = x0<=x1?x0:x1,
              nx1 = x0<=x1?x1:x0,
              ny0 = y0<=y1?y0:y1,
              ny1 = y0<=y1?y1:y0,
              sx0 = (int)(16 + nx0*(visu.width() - 32)/std::max((ulongT)1,siz - one)),
              sx1 = (int)(15 + (nx1 + 1)*(visu.width() - 32)/std::max((ulongT)1,siz - one)),
              sy0 = 16 + ny0,
              sy1 = 16 + ny1;
            if (y0>=0 && y1>=0)
              visu.draw_rectangle(sx0,sy0,sx1,sy1,gray,0.5f).draw_rectangle(sx0,sy0,sx1,sy1,black,0.5f,0xCCCCCCCCU);
            else visu.draw_rectangle(sx0,0,sx1,visu.height() - 17,gray,0.5f).
                   draw_line(sx0,16,sx0,visu.height() - 17,black,0.5f,0xCCCCCCCCU).
                   draw_line(sx1,16,sx1,visu.height() - 17,black,0.5f,0xCCCCCCCCU);
          }
          if (mouse_x>=16 && mouse_y>=16 && mouse_x<visu.width() - 16 && mouse_y<visu.height() - 16) {
            if (graph) visu.draw_line(mouse_x,16,mouse_x,visu.height() - 17,black,0.5f,0x55555555U);
            const unsigned int
              x = (unsigned int)cimg::round((mouse_x - 16.f)*(siz - one)/(disp.width() - 32),1,one?0:-1);
            const double cx = nxmin + x*(nxmax - nxmin)/std::max((ulongT)1,siz - 1);
            if (_spectrum>=7)
              cimg_snprintf(message,message._width,"Value[%u:%g] = ( %g %g %g ... %g %g %g )",x,cx,
                            (double)(*this)(x,0,0,0),(double)(*this)(x,0,0,1),(double)(*this)(x,0,0,2),
                            (double)(*this)(x,0,0,_spectrum - 4),(double)(*this)(x,0,0,_spectrum - 3),
                            (double)(*this)(x,0,0,_spectrum - 1));
            else {
              cimg_snprintf(message,message._width,"Value[%u:%g] = ( ",x,cx);
              unsigned int len = (unsigned int)std::strlen(message);
              cimg_forC(*this,c)
                cimg_snprintf(message._data + len,message._width - len,"%g ",(double)(*this)(x,0,0,c));
              len = (unsigned int)std::strlen(message);
              cimg_snprintf(message._data + len,message._width - len,")");
            }
            if (x0>=0 && x1>=0) {
              const unsigned int
                nx0 = (unsigned int)(x0<=x1?x0:x1),
                nx1 = (unsigned int)(x0<=x1?x1:x0),
                ny0 = (unsigned int)(y0<=y1?y0:y1),
                ny1 = (unsigned int)(y0<=y1?y1:y0),
                len = (unsigned int)std::strlen(message);
              const double
                cx0 = nxmin + nx0*(nxmax - nxmin)/std::max((ulongT)1,siz - 1),
                cx1 = nxmin + (nx1 + one)*(nxmax - nxmin)/std::max((ulongT)1,siz - 1),
                cy0 = nymax - ny0*(nymax - nymin)/(visu._height - 32),
                cy1 = nymax - ny1*(nymax - nymin)/(visu._height - 32);
              if (y0>=0 && y1>=0)
                cimg_snprintf(message._data + len,message._width - len," - Range ( %u:%g, %g ) - ( %u:%g, %g )",
                             x0,cx0,cy0,x1 + one,cx1,cy1);
              else
                cimg_snprintf(message._data + len,message._width - len," - Range [ %u:%g - %u:%g ]",
                             x0,cx0,x1 + one,cx1);
            }
            text.assign().draw_text(0,0,message,white,ngray,1,13).resize(-100,-100,1,3);
            visu.draw_image((visu.width() - text.width())/2,1,~text);
          }
          visu.display(disp);
        }

        // Test keys.
        CImg<charT> filename(1024);
        switch (okey = key) {
#if cimg_OS!=2
        case cimg::keyCTRLRIGHT : case cimg::keySHIFTRIGHT :
#endif
        case cimg::keyCTRLLEFT : case cimg::keySHIFTLEFT : okey = 0; break;
        case cimg::keyD : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
          disp.set_fullscreen(false).
            resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                   CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false).
            _is_resized = true;
          disp.set_key(key,false); okey = 0;
        } break;
        case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
          disp.set_fullscreen(false).
            resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false)._is_resized = true;
          disp.set_key(key,false); okey = 0;
        } break;
        case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(CImgDisplay::screen_width()/2,
                                    CImgDisplay::screen_height()/2,1),false)._is_resized = true;
            disp.set_key(key,false); okey = 0;
          } break;
        case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.resize(disp.screen_width(),disp.screen_height(),false).toggle_fullscreen()._is_resized = true;
            disp.set_key(key,false); okey = 0;
          } break;
        case cimg::keyS : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            if (visu || visu0) {
              CImg<ucharT> &screen = visu?visu:visu0;
              do {
                cimg_snprintf(filename,filename._width,cimg_appname "_%.6u."
#ifdef cimg_use_png
                              "png",
#else
                              "bmp",
#endif
                              snap_number++);
              } while (cimg::path_exists(filename));
              (+screen).__draw_text(" Saving snapshot... ",font_size,0).display(disp);
              screen.save(filename);
              (+screen).__draw_text(" Snapshot '%s' saved. ",font_size,0,filename._data).display(disp);
            }
            disp.set_key(key,false); okey = 0;
          } break;
        case cimg::keyO : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            if (visu || visu0) {
              CImg<ucharT> &screen = visu?visu:visu0;
              do {

#ifdef cimg_use_zlib
                cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimgz",snap_number++);
#else
                cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimg",snap_number++);
#endif
              } while (cimg::path_exists(filename));
              (+screen).__draw_text(" Saving instance... ",font_size,0).display(disp);
              save(filename);
              (+screen).__draw_text(" Instance '%s' saved. ",font_size,0,filename._data).display(disp);
            }
            disp.set_key(key,false); okey = 0;
          } break;
        }

        // Handle mouse motion and mouse buttons.
        if (obutton!=button || omouse_x!=mouse_x || omouse_y!=mouse_y) {
          visu.assign();
          if (disp.mouse_x()>=0 && disp.mouse_y()>=0) {
            const int
              mx = (mouse_x - 16)*(int)(siz - one)/(disp.width() - 32),
              cx = cimg::cut(mx,0,(int)(siz - 1 - one)),
              my = mouse_y - 16,
              cy = cimg::cut(my,0,disp.height() - 32);
            if (button&1) {
              if (!obutton) { x0 = cx; y0 = -1; } else { x1 = cx; y1 = -1; }
            }
            else if (button&2) {
              if (!obutton) { x0 = cx; y0 = cy; } else { x1 = cx; y1 = cy; }
            }
            else if (obutton) { x1 = x1>=0?cx:-1; y1 = y1>=0?cy:-1; selected = true; }
          } else if (!button && obutton) selected = true;
          obutton = button; omouse_x = mouse_x; omouse_y = mouse_y;
        }
        if (disp.is_resized()) { disp.resize(false); visu0.assign(); }
        if (visu && visu0) disp.wait();
        if (!exit_on_anykey && okey && okey!=cimg::keyESC &&
            (okey!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          disp.set_key(key,false);
          okey = 0;
        }
      }

      disp._normalization = old_normalization;
      if (x1>=0 && x1<x0) cimg::swap(x0,x1);
      if (y1<y0) cimg::swap(y0,y1);
      disp.set_key(okey);
      return CImg<intT>(4,1,1,1,x0,y0,x1>=0?x1 + (int)one:-1,y1);
    }

    //! Load image from a file.
    /**
       \param filename Filename, as a C-string.
       \note The extension of \c filename defines the file format. If no filename
       extension is provided, CImg<T>::get_load() will try to load the file as a .cimg or .cimgz file.
    **/
    CImg<T>& load(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load(): Specified filename is (null).",
                                    cimg_instance);

      if (!cimg::strncasecmp(filename,"http://",7) || !cimg::strncasecmp(filename,"https://",8)) {
        CImg<charT> filename_local(256);
        load(cimg::load_network(filename,filename_local));
        std::remove(filename_local);
        return *this;
      }

      const char *const ext = cimg::split_filename(filename);
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      bool is_loaded = true;
      try {
#ifdef cimg_load_plugin
        cimg_load_plugin(filename);
#endif
#ifdef cimg_load_plugin1
        cimg_load_plugin1(filename);
#endif
#ifdef cimg_load_plugin2
        cimg_load_plugin2(filename);
#endif
#ifdef cimg_load_plugin3
        cimg_load_plugin3(filename);
#endif
#ifdef cimg_load_plugin4
        cimg_load_plugin4(filename);
#endif
#ifdef cimg_load_plugin5
        cimg_load_plugin5(filename);
#endif
#ifdef cimg_load_plugin6
        cimg_load_plugin6(filename);
#endif
#ifdef cimg_load_plugin7
        cimg_load_plugin7(filename);
#endif
#ifdef cimg_load_plugin8
        cimg_load_plugin8(filename);
#endif
        // Text formats.
        if (!cimg::strcasecmp(ext,"asc")) load_ascii(filename);
        else if (!cimg::strcasecmp(ext,"csv") ||
                 !cimg::strcasecmp(ext,"dlm") ||
                 !cimg::strcasecmp(ext,"txt")) load_dlm(filename);
        else if (!cimg::strcasecmp(ext,"pdf")) load_pdf_external(filename);

        // 2D binary formats.
        else if (!cimg::strcasecmp(ext,"bmp")) load_bmp(filename);
        else if (!cimg::strcasecmp(ext,"jpg") ||
                 !cimg::strcasecmp(ext,"jpeg") ||
                 !cimg::strcasecmp(ext,"jpe") ||
                 !cimg::strcasecmp(ext,"jfif") ||
                 !cimg::strcasecmp(ext,"jif")) load_jpeg(filename);
        else if (!cimg::strcasecmp(ext,"png")) load_png(filename);
        else if (!cimg::strcasecmp(ext,"ppm") ||
                 !cimg::strcasecmp(ext,"pgm") ||
                 !cimg::strcasecmp(ext,"pnm") ||
                 !cimg::strcasecmp(ext,"pbm") ||
                 !cimg::strcasecmp(ext,"pnk")) load_pnm(filename);
        else if (!cimg::strcasecmp(ext,"pfm")) load_pfm(filename);
        else if (!cimg::strcasecmp(ext,"tif") ||
                 !cimg::strcasecmp(ext,"tiff")) load_tiff(filename);
        else if (!cimg::strcasecmp(ext,"exr")) load_exr(filename);
        else if (!cimg::strcasecmp(ext,"arw") ||
                 !cimg::strcasecmp(ext,"cr2") ||
                 !cimg::strcasecmp(ext,"crw") ||
                 !cimg::strcasecmp(ext,"dcr") ||
                 !cimg::strcasecmp(ext,"dng") ||
                 !cimg::strcasecmp(ext,"mrw") ||
                 !cimg::strcasecmp(ext,"nef") ||
                 !cimg::strcasecmp(ext,"orf") ||
                 !cimg::strcasecmp(ext,"pix") ||
                 !cimg::strcasecmp(ext,"ptx") ||
                 !cimg::strcasecmp(ext,"raf") ||
                 !cimg::strcasecmp(ext,"srf")) load_dcraw_external(filename);
        else if (!cimg::strcasecmp(ext,"gif")) load_gif_external(filename);
        else if (!cimg::strcasecmp(ext,"heic") ||
                 !cimg::strcasecmp(ext,"heif") ||
                 !cimg::strcasecmp(ext,"avif")) load_heif(filename);
        else if (!cimg::strcasecmp(ext,"webp")) load_webp(filename);
        else if (!cimg::strcasecmp(ext,"jxl")) load_jxl(filename);

        // 3D binary formats.
        else if (!cimg::strcasecmp(ext,"dcm") ||
                 !cimg::strcasecmp(ext,"dicom")) load_medcon_external(filename);
        else if (!cimg::strcasecmp(ext,"hdr") ||
                 !cimg::strcasecmp(ext,"nii")) load_analyze(filename);
        else if (!cimg::strcasecmp(ext,"par") ||
                 !cimg::strcasecmp(ext,"rec")) load_parrec(filename);
        else if (!cimg::strcasecmp(ext,"mnc")) load_minc2(filename);
        else if (!cimg::strcasecmp(ext,"inr")) load_inr(filename);
        else if (!cimg::strcasecmp(ext,"pan")) load_pandore(filename);
        else if (!cimg::strcasecmp(ext,"cimg") ||
                 !cimg::strcasecmp(ext,"cimgz") ||
                 !*ext)  return load_cimg(filename);

        // Archive files.
        else if (!cimg::strcasecmp(ext,"gz")) load_gzip_external(filename);

        // Image sequences.
        else if (!cimg::strcasecmp(ext,"avi") ||
                 !cimg::strcasecmp(ext,"mov") ||
                 !cimg::strcasecmp(ext,"asf") ||
                 !cimg::strcasecmp(ext,"divx") ||
                 !cimg::strcasecmp(ext,"flv") ||
                 !cimg::strcasecmp(ext,"mpg") ||
                 !cimg::strcasecmp(ext,"m1v") ||
                 !cimg::strcasecmp(ext,"m2v") ||
                 !cimg::strcasecmp(ext,"m4v") ||
                 !cimg::strcasecmp(ext,"mjp") ||
                 !cimg::strcasecmp(ext,"mp4") ||
                 !cimg::strcasecmp(ext,"mkv") ||
                 !cimg::strcasecmp(ext,"mpe") ||
                 !cimg::strcasecmp(ext,"movie") ||
                 !cimg::strcasecmp(ext,"ogm") ||
                 !cimg::strcasecmp(ext,"ogg") ||
                 !cimg::strcasecmp(ext,"ogv") ||
                 !cimg::strcasecmp(ext,"qt") ||
                 !cimg::strcasecmp(ext,"rm") ||
                 !cimg::strcasecmp(ext,"vob") ||
                 !cimg::strcasecmp(ext,"webm") ||
                 !cimg::strcasecmp(ext,"wmv") ||
                 !cimg::strcasecmp(ext,"xvid") ||
                 !cimg::strcasecmp(ext,"mpeg")) load_video(filename);
        else is_loaded = false;
      } catch (CImgIOException&) { is_loaded = false; }

      // If nothing was loaded, try to guess the file format from the magic number in the file.
      if (!is_loaded) {
        std::FILE *file = cimg::std_fopen(filename,"rb");
        if (!file) {
          cimg::exception_mode(omode);
          throw CImgIOException(_cimg_instance
                                "load(): Failed to open file '%s'.",
                                cimg_instance,
                                filename);
        }

        const char *const f_type = cimg::ftype(file,filename);
        cimg::fclose(file);
        is_loaded = true;
        try {
          if (!cimg::strcasecmp(f_type,"pnm")) load_pnm(filename);
          else if (!cimg::strcasecmp(f_type,"pfm")) load_pfm(filename);
          else if (!cimg::strcasecmp(f_type,"bmp")) load_bmp(filename);
          else if (!cimg::strcasecmp(f_type,"inr")) load_inr(filename);
          else if (!cimg::strcasecmp(f_type,"jpg")) load_jpeg(filename);
          else if (!cimg::strcasecmp(f_type,"pan")) load_pandore(filename);
          else if (!cimg::strcasecmp(f_type,"png")) load_png(filename);
          else if (!cimg::strcasecmp(f_type,"tif")) load_tiff(filename);
          else if (!cimg::strcasecmp(f_type,"gif")) load_gif_external(filename);
          else if (!cimg::strcasecmp(f_type,"heif")) load_heif(filename);
          else if (!cimg::strcasecmp(f_type,"dcm")) load_medcon_external(filename);
          else if (!cimg::strcasecmp(f_type,"webp")) load_webp(filename);
          else if (!cimg::strcasecmp(f_type,"jxl")) load_jxl(filename);
          else is_loaded = false;
        } catch (CImgIOException&) { is_loaded = false; }
      }

      // If nothing was loaded, try to load the file by other means.
      if (!is_loaded) {
        try {
          load_other(filename);
        } catch (CImgIOException&) {
          cimg::exception_mode(omode);
          throw CImgIOException(_cimg_instance
                                "load(): Failed to recognize format of file '%s'.",
                                cimg_instance,
                                filename);
        }
      }
      cimg::exception_mode(omode);
      return *this;
    }

    //! Load image from a file \newinstance.
    static CImg<T> get_load(const char *const filename) {
      return CImg<T>().load(filename);
    }

    //! Load image from an ASCII file.
    /**
       \param filename Filename, as a C -string.
    **/
    CImg<T>& load_ascii(const char *const filename) {
      return _load_ascii(0,filename);
    }

    //! Load image from an ASCII file \newinstance.
    static CImg<T> get_load_ascii(const char *const filename) {
      return CImg<T>().load_ascii(filename);
    }

    //! Load image from an ASCII file \inplace.
    CImg<T>& load_ascii(std::FILE *const file) {
      return _load_ascii(file,0);
    }

    //! Load image from an ASCII file \newinstance.
    static CImg<T> get_load_ascii(std::FILE *const file) {
      return CImg<T>().load_ascii(file);
    }

    CImg<T>& _load_ascii(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_ascii(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      CImg<charT> line(256); *line = 0;
      int err = std::fscanf(nfile,"%255[^\n]",line._data);
      unsigned int dx = 0, dy = 1, dz = 1, dc = 1;
      cimg_sscanf(line._data,"%u%*c%u%*c%u%*c%u",&dx,&dy,&dz,&dc);
      err = std::fscanf(nfile,"%*[^0-9.eEinfa+-]");
      if (!dx || !dy || !dz || !dc) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_ascii(): Invalid ASCII header in file '%s', image dimensions are set "
                              "to (%u,%u,%u,%u).",
                              cimg_instance,
                              filename?filename:"(FILE*)",dx,dy,dz,dc);
      }
      assign(dx,dy,dz,dc);
      const ulongT siz = size();
      ulongT off = 0;
      double val;
      T *ptr = _data;
      for (err = 1, off = 0; off<siz && err==1; ++off) {
        err = std::fscanf(nfile,"%lf%*[^0-9.eEinfa+-]",&val);
        *(ptr++) = (T)val;
      }
      if (err!=1)
        cimg::warn(_cimg_instance
                   "load_ascii(): Only %lu/%lu values read from file '%s'.",
                   cimg_instance,
                   off - 1,siz,filename?filename:"(FILE*)");

      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a DLM file.
    /**
      \param filename Filename, as a C-string.
    **/
    CImg<T>& load_dlm(const char *const filename) {
      return _load_dlm(0,filename);
    }

    //! Load image from a DLM file \newinstance.
    static CImg<T> get_load_dlm(const char *const filename) {
      return CImg<T>().load_dlm(filename);
    }

    //! Load image from a DLM file \inplace.
    CImg<T>& load_dlm(std::FILE *const file) {
      return _load_dlm(file,0);
    }

    //! Load image from a DLM file \newinstance.
    static CImg<T> get_load_dlm(std::FILE *const file) {
      return CImg<T>().load_dlm(file);
    }

    CImg<T>& _load_dlm(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_dlm(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"r");
      CImg<charT> delimiter(256), tmp(256); *delimiter = *tmp = 0;
      unsigned int cdx = 0, dx = 0, dy = 0;
      int err = 0;
      double val;
      assign(256,256,1,1,(T)0);
      while ((err = std::fscanf(nfile,"%lf%255[^0-9eEinfa.+-]",&val,delimiter._data))>0) {
        if (err>0) (*this)(cdx++,dy) = (T)val;
        if (cdx>=_width) resize(3*_width/2,_height,1,1,0);
        char c = 0;
        if (!cimg_sscanf(delimiter._data,"%255[^\n]%c",tmp._data,&c) || c=='\n') {
          dx = std::max(cdx,dx);
          if (++dy>=_height) resize(_width,3*_height/2,1,1,0);
          cdx = 0;
        }
      }
      if (cdx && err==1) { dx = cdx; ++dy; }
      if (!dx || !dy) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_dlm(): Invalid DLM file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      resize(dx,dy,1,1,0);
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a BMP file.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_bmp(const char *const filename) {
      return _load_bmp(0,filename);
    }

    //! Load image from a BMP file \newinstance.
    static CImg<T> get_load_bmp(const char *const filename) {
      return CImg<T>().load_bmp(filename);
    }

    //! Load image from a BMP file \inplace.
    CImg<T>& load_bmp(std::FILE *const file) {
      return _load_bmp(file,0);
    }

    //! Load image from a BMP file \newinstance.
    static CImg<T> get_load_bmp(std::FILE *const file) {
      return CImg<T>().load_bmp(file);
    }

    CImg<T>& _load_bmp(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_bmp(): Specified filename is (null).",
                                    cimg_instance);

      const ulongT fsiz = (ulongT)(file?cimg::fsize(file):cimg::fsize(filename));
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      CImg<ucharT> header(54);
      cimg::fread(header._data,54,nfile);
      if (*header!='B' || header[1]!='M') {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Invalid BMP file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }

      // Read header and pixel buffer.
      int
        file_size = header[0x02] + (header[0x03]<<8) + (header[0x04]<<16) + (header[0x05]<<24),
        offset = header[0x0A] + (header[0x0B]<<8) + (header[0x0C]<<16) + (header[0x0D]<<24),
        header_size = header[0x0E] + (header[0x0F]<<8) + (header[0x10]<<16) + (header[0x11]<<24),
        dx = header[0x12] + (header[0x13]<<8) + (header[0x14]<<16) + (header[0x15]<<24),
        dy = header[0x16] + (header[0x17]<<8) + (header[0x18]<<16) + (header[0x19]<<24),
        compression = header[0x1E] + (header[0x1F]<<8) + (header[0x20]<<16) + (header[0x21]<<24),
        nb_colors = header[0x2E] + (header[0x2F]<<8) + (header[0x30]<<16) + (header[0x31]<<24),
        bpp = header[0x1C] + (header[0x1D]<<8);

      if ((ulongT)file_size!=fsiz)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Invalid file_size %d specified in filename '%s' (expected %lu).",
                              cimg_instance,
                              file_size,filename?filename:"(FILE*)",fsiz);

      if (header_size<0 || header_size>=file_size)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Invalid header size %d specified in filename '%s'.",
                              cimg_instance,
                              header_size,filename?filename:"(FILE*)");

      if (offset<0 || offset>=file_size)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Invalid offset %d specified in filename '%s'.",
                              cimg_instance,
                              offset,filename?filename:"(FILE*)");

      if (dx<0 || dy<0)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Invalid image size (%d,%d) specified in filename '%s'.",
                              cimg_instance,
                              dx,dy,filename?filename:"(FILE*)");

      if (header_size>40) cimg::fseek(nfile,header_size - 40,SEEK_CUR);
      const int
        dx_bytes = (bpp==1)?(dx/8 + (dx%8?1:0)):((bpp==4)?(dx/2 + (dx%2)):(int)((longT)dx*bpp/8)),
        align_bytes = (4 - dx_bytes%4)%4;
      const ulongT
        cimg_iobuffer = (ulongT)24*1024*1024,
        buf_size = (ulongT)cimg::abs((longT)dy)*(dx_bytes + align_bytes);

      if (buf_size>=fsiz)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): File size %lu for filename '%s' does not match "
                              "encoded image dimensions (%d,%d).",
                              cimg_instance,
                              (long)fsiz,filename?filename:"(FILE*)",dx,dy);

      CImg<intT> colormap;
      if (bpp<16) {
        const int max_colors = 1<<bpp;
        if (nb_colors<=0 || nb_colors>max_colors) nb_colors = max_colors;
      } else nb_colors = 0;
      if (nb_colors) { colormap.assign(nb_colors); cimg::fread(colormap._data,nb_colors,nfile); }

      const int xoffset = offset - 14 - header_size - 4*nb_colors;
      if (xoffset<0 || xoffset>=file_size)
        throw CImgIOException(_cimg_instance
                              "load_bmp(): Malformed header in filename '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      cimg::fseek(nfile,xoffset,SEEK_CUR);

      CImg<ucharT> buffer;
      if (buf_size<cimg_iobuffer) {
        buffer.assign(buf_size,1,1,1,0);
        cimg::fread(buffer._data,buf_size,nfile);
      } else buffer.assign(dx_bytes + align_bytes);
      unsigned char *ptrs = buffer;

      // Decompress buffer (if necessary).
      if (compression==1 || compression==2) {
        if (file)
          throw CImgIOException(_cimg_instance
                                "load_bmp(): Unable to load compressed data from '(*FILE)' inputs.",
                                cimg_instance);
        else {
          if (!file) cimg::fclose(nfile);
          return load_other(filename);
        }
      }

      // Read pixel data.
      assign(dx,cimg::abs(dy),1,3,0);
      switch (bpp) {
      case 1 : { // Monochrome
        if (colormap._width>=2) for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          unsigned char mask = 0x80, val = 0;
          cimg_forX(*this,x) {
            if (mask==0x80) val = *(ptrs++);
            const unsigned char *col = (unsigned char*)(colormap._data + (val&mask?1:0));
            (*this)(x,y,2) = (T)*(col++);
            (*this)(x,y,1) = (T)*(col++);
            (*this)(x,y,0) = (T)*(col++);
            mask = cimg::ror(mask);
          }
          ptrs+=align_bytes;
        }
      } break;
      case 4 : { // 16 colors
        if (colormap._width>=16) for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          unsigned char mask = 0xF0, val = 0;
          cimg_forX(*this,x) {
            if (mask==0xF0) val = *(ptrs++);
            const unsigned char color = (unsigned char)((mask<16)?(val&mask):((val&mask)>>4));
            const unsigned char *col = (unsigned char*)(colormap._data + color);
            (*this)(x,y,2) = (T)*(col++);
            (*this)(x,y,1) = (T)*(col++);
            (*this)(x,y,0) = (T)*(col++);
            mask = cimg::ror(mask,4);
          }
          ptrs+=align_bytes;
        }
      } break;
      case 8 : { // 256 colors
        if (colormap._width>=256) for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          cimg_forX(*this,x) {
            const unsigned char *col = (unsigned char*)(colormap._data + *(ptrs++));
            (*this)(x,y,2) = (T)*(col++);
            (*this)(x,y,1) = (T)*(col++);
            (*this)(x,y,0) = (T)*(col++);
          }
          ptrs+=align_bytes;
        }
      } break;
      case 16 : { // 16 bits colors (RGB565)
        for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          cimg_forX(*this,x) {
            const unsigned char c1 = *(ptrs++), c2 = *(ptrs++);
            const unsigned short col = (unsigned short)c2<<8 | c1;
            (*this)(x,y,2) = (T)((col&0x1F)<<3);
            (*this)(x,y,1) = (T)(((col>>5)&0x3F)<<3);
            (*this)(x,y,0) = (T)(((col>>11)&0x1F)<<3);
          }
          ptrs+=align_bytes;
        }
      } break;
      case 24 : { // 24 bits colors
        for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          cimg_forX(*this,x) {
            (*this)(x,y,2) = (T)*(ptrs++);
            (*this)(x,y,1) = (T)*(ptrs++);
            (*this)(x,y,0) = (T)*(ptrs++);
          }
          ptrs+=align_bytes;
        }
      } break;
      case 32 : { // 32 bits colors
        for (int y = height() - 1; y>=0; --y) {
          if (buf_size>=cimg_iobuffer) {
            if (!cimg::fread(ptrs=buffer._data,dx_bytes,nfile)) break;
            cimg::fseek(nfile,align_bytes,SEEK_CUR);
          }
          cimg_forX(*this,x) {
            (*this)(x,y,2) = (T)*(ptrs++);
            (*this)(x,y,1) = (T)*(ptrs++);
            (*this)(x,y,0) = (T)*(ptrs++);
            ++ptrs;
          }
          ptrs+=align_bytes;
        }
      } break;
      }
      if (dy<0) mirror('y');
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a JPEG file.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_jpeg(const char *const filename) {
      return _load_jpeg(0,filename);
    }

    //! Load image from a JPEG file \newinstance.
    static CImg<T> get_load_jpeg(const char *const filename) {
      return CImg<T>().load_jpeg(filename);
    }

    //! Load image from a JPEG file \inplace.
    CImg<T>& load_jpeg(std::FILE *const file) {
      return _load_jpeg(file,0);
    }

    //! Load image from a JPEG file \newinstance.
    static CImg<T> get_load_jpeg(std::FILE *const file) {
      return CImg<T>().load_jpeg(file);
    }

    // Custom error handler for libjpeg.
#ifdef cimg_use_jpeg
    struct _cimg_error_mgr {
      struct jpeg_error_mgr original;
      jmp_buf setjmp_buffer;
      char message[JMSG_LENGTH_MAX];
    };

    typedef struct _cimg_error_mgr *_cimg_error_ptr;

    METHODDEF(void) _cimg_jpeg_error_exit(j_common_ptr cinfo) {
      _cimg_error_ptr c_err = (_cimg_error_ptr) cinfo->err; // Return control to the setjmp point
      (*cinfo->err->format_message)(cinfo,c_err->message);
      jpeg_destroy(cinfo); // Clean memory and temp files
      longjmp(c_err->setjmp_buffer,1);
    }
#endif

    CImg<T>& _load_jpeg(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_jpeg(): Specified filename is (null).",
                                    cimg_instance);

#ifndef cimg_use_jpeg
      if (file)
        throw CImgIOException(_cimg_instance
                              "load_jpeg(): Unable to load data from '(FILE*)' unless libjpeg is enabled.",
                              cimg_instance);
      else return load_other(filename);
#else

#if defined __GNUC__
      const char *volatile nfilename = filename; // Use 'volatile' to avoid (wrong) g++ warning
      std::FILE *volatile nfile = file?file:cimg::fopen(nfilename,"rb");
#else
      const char *nfilename = filename;
      std::FILE *nfile = file?file:cimg::fopen(nfilename,"rb");
#endif

      struct jpeg_decompress_struct cinfo;
      struct _cimg_error_mgr jerr;
      cinfo.err = jpeg_std_error(&jerr.original);
      jerr.original.error_exit = _cimg_jpeg_error_exit;
      if (setjmp(jerr.setjmp_buffer)) { // JPEG error
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                             "load_jpeg(): Error message returned by libjpeg: %s.",
                             cimg_instance,jerr.message);
      }

      jpeg_create_decompress(&cinfo);
      jpeg_stdio_src(&cinfo,nfile);
      jpeg_read_header(&cinfo,TRUE);
      jpeg_start_decompress(&cinfo);

      if (cinfo.output_components!=1 && cinfo.output_components!=3 && cinfo.output_components!=4) {
        if (!file) {
          cimg::fclose(nfile);
          return load_other(nfilename);
        } else
          throw CImgIOException(_cimg_instance
                                "load_jpeg(): Failed to load JPEG data from file '%s'.",
                                cimg_instance,nfilename?nfilename:"(FILE*)");
      }
      CImg<ucharT> buffer(cinfo.output_width*cinfo.output_components);
      JSAMPROW row_pointer[1];
      try { assign(cinfo.output_width,cinfo.output_height,1,cinfo.output_components); }
      catch (...) { if (!file) cimg::fclose(nfile); throw; }
      T *ptr_r = _data, *ptr_g = _data + 1UL*_width*_height, *ptr_b = _data + 2UL*_width*_height,
        *ptr_a = _data + 3UL*_width*_height;
      while (cinfo.output_scanline<cinfo.output_height) {
        *row_pointer = buffer._data;
        if (jpeg_read_scanlines(&cinfo,row_pointer,1)!=1) {
          cimg::warn(_cimg_instance
                     "load_jpeg(): Incomplete data in file '%s'.",
                     cimg_instance,nfilename?nfilename:"(FILE*)");
          break;
        }
        const unsigned char *ptrs = buffer._data;
        switch (_spectrum) {
        case 1 : {
          cimg_forX(*this,x) *(ptr_r++) = (T)*(ptrs++);
        } break;
        case 3 : {
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            *(ptr_g++) = (T)*(ptrs++);
            *(ptr_b++) = (T)*(ptrs++);
          }
        } break;
        case 4 : {
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            *(ptr_g++) = (T)*(ptrs++);
            *(ptr_b++) = (T)*(ptrs++);
            *(ptr_a++) = (T)*(ptrs++);
          }
        } break;
        }
      }
      jpeg_finish_decompress(&cinfo);
      jpeg_destroy_decompress(&cinfo);
      if (!file) cimg::fclose(nfile);
      return *this;
#endif
    }

    //! Load image from a JPEG XL file.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_jxl(const char *const filename) {
      return _load_jxl(0,filename);
    }

    //! Load image from a JPEG XL file \newinstance.
    static CImg<T> get_load_jxl(const char *const filename) {
      return CImg<T>().load_jxl(filename);
    }

    //! Load image from a JPEG XL file \inplace.
    CImg<T>& load_jxl(std::FILE *const file) {
      return _load_jxl(file,0);
    }

    //! Load image from a JPEG XL file \newinstance.
    static CImg<T> get_load_jxl(std::FILE *const file) {
      return CImg<T>().load_jxl(file);
    }

    CImg<T>& _load_jxl(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_jxl(): Specified filename is (null).",
                                    cimg_instance);

#ifndef cimg_use_jxl
      if (file)
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Unable to load data from '(FILE*)' unless libjxl is enabled.",
                              cimg_instance);
      else return load_other(filename);
#else
      const char *nfilename = filename;
      std::FILE *nfile = file?file:cimg::fopen(nfilename,"rb");
      const long dataSize = cimg::fsize(nfile);
      if (dataSize<=0) {
        cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Failed to get file size '%s'.",
                              cimg_instance,
                              nfilename);
      }
      CImg<ucharT> buffer(dataSize);
      cimg::fread(buffer._data,buffer._width,nfile);
      cimg::fclose(nfile);

      bool hasAlpha = false, isGray = false;
      uint32_t nChannels = 0;
      JxlBasicInfo jxlInfo;
      JxlPixelFormat format = { 1,JXL_TYPE_UINT8,cimg::endianness()?JXL_BIG_ENDIAN:JXL_LITTLE_ENDIAN,0 };
      CImg<ucharT> imgData;
      JxlDecoder *decoder = JxlDecoderCreate(NULL);
      if (JXL_DEC_SUCCESS!=JxlDecoderSubscribeEvents(decoder,JXL_DEC_BASIC_INFO | JXL_DEC_FULL_IMAGE)) {
        JxlDecoderDestroy(decoder);
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Failed to configure decoder '%s'.",
                              cimg_instance,
                              nfilename);
      }
      if (JXL_DEC_SUCCESS!=JxlDecoderSetInput(decoder,buffer._data,buffer._width)) {
        JxlDecoderDestroy(decoder);
        throw CImgIOException(_cimg_instance
                              "load_jxl(): Failed to load image data '%s'.",
                              cimg_instance,
                              nfilename);
      }
      JxlDecoderCloseInput(decoder);

      while (true) {
        JxlDecoderStatus status = JxlDecoderProcessInput(decoder);
        if (status==JXL_DEC_SUCCESS || status==JXL_DEC_FULL_IMAGE) break;
        else if (status==JXL_DEC_ERROR || status==JXL_DEC_NEED_MORE_INPUT) {
          JxlDecoderDestroy(decoder);
          throw CImgIOException(_cimg_instance
                                "load_jxl(): Failed to decode image '%s'.",
                                cimg_instance,
                                nfilename);
        } else if (status==JXL_DEC_BASIC_INFO) {
          if (JXL_DEC_SUCCESS!=JxlDecoderGetBasicInfo(decoder,&jxlInfo)) {
            JxlDecoderDestroy(decoder);
            throw CImgIOException(_cimg_instance
                                  "load_jxl(): Failed to load image data '%s'.",
                                  cimg_instance,
                                  nfilename);
          }
          if (jxlInfo.have_animation!=0) {
            JxlDecoderDestroy(decoder);
            throw CImgIOException(_cimg_instance
                                  "load_jxl(): Does not support animated JPEG XL '%s'.",
                                  cimg_instance,
                                  nfilename);
          }
          hasAlpha = jxlInfo.alpha_bits!=0;
          nChannels = hasAlpha?jxlInfo.num_color_channels + 1:jxlInfo.num_color_channels;
          isGray = jxlInfo.num_color_channels==1;
        } else if (status==JXL_DEC_NEED_IMAGE_OUT_BUFFER) {
          std::size_t imgDataSize = 0;
          format.num_channels = nChannels;
          format.data_type = jxlInfo.bits_per_sample==16?JXL_TYPE_UINT16:JXL_TYPE_UINT8;
          if (JXL_DEC_SUCCESS!=JxlDecoderImageOutBufferSize(decoder,&format,&imgDataSize)) {
            JxlDecoderDestroy(decoder);
            throw CImgIOException(_cimg_instance
                                  "load_jxl(): Failed to decode image data '%s'.",
                                  cimg_instance,
                                  nfilename);
          }
          imgData.assign(imgDataSize);
          if (JXL_DEC_SUCCESS!=JxlDecoderSetImageOutBuffer(decoder,&format,(void*)imgData.data(),imgDataSize)) {
            JxlDecoderDestroy(decoder);
            throw CImgIOException(_cimg_instance
                                  "load_jxl(): Failed to set decode buffer '%s'.",
                                  cimg_instance,
                                  nfilename);
          }
        }
      }

      assign(jxlInfo.xsize,jxlInfo.ysize,1,nChannels);
      T
        *ptr_r = data(0,0,0,0),
        *ptr_g = isGray?0:data(0,0,0,1),
        *ptr_b = isGray?0:data(0,0,0,2),
        *ptr_a = !hasAlpha?0:data(0,0,0,isGray?1:3);
      switch (jxlInfo.bits_per_sample) {
      case 8: {
        cimg_forY(*this,y) {
          const uint8_t *ptrs = (uint8_t*)&imgData[y*_width*_spectrum*sizeof(uint8_t)];
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            if (ptr_g) *(ptr_g++) = (T)*(ptrs++);
            if (ptr_b) *(ptr_b++) = (T)*(ptrs++);
            if (ptr_a) *(ptr_a++) = (T)*(ptrs++);
          }
        }
      } break;
      case 16: {
        cimg_forY(*this,y) {
          const uint16_t *ptrs = (uint16_t*)&imgData[y*_width*_spectrum*sizeof(uint16_t)];
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            if (ptr_g) *(ptr_g++) = (T)*(ptrs++);
            if (ptr_b) *(ptr_b++) = (T)*(ptrs++);
            if (ptr_a) *(ptr_a++) = (T)*(ptrs++);
          }
        }
      } break;
      }
      JxlDecoderDestroy(decoder);
      return *this;
#endif
    }

    //! Load image from a file, using Magick++ library.
    /**
       \param filename Filename, as a C-string.
    **/
    // Added April/May 2006 by Christoph Hormann <chris_hormann@gmx.de>.
    CImg<T>& load_magick(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_magick(): Specified filename is (null).",
                                    cimg_instance);

#ifdef cimg_use_magick
      Magick::Image image(filename);
      const unsigned int W = image.size().width(), H = image.size().height();
      switch (image.type()) {
      case Magick::PaletteMatteType :
      case Magick::TrueColorMatteType :
      case Magick::ColorSeparationType : {
        assign(W,H,1,4);
        T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2), *ptr_a = data(0,0,0,3);
        Magick::PixelPacket *pixels = image.getPixels(0,0,W,H);
        for (ulongT off = (ulongT)W*H; off; --off) {
          *(ptr_r++) = (T)(pixels->red);
          *(ptr_g++) = (T)(pixels->green);
          *(ptr_b++) = (T)(pixels->blue);
          *(ptr_a++) = (T)(pixels->opacity);
          ++pixels;
        }
      } break;
      case Magick::PaletteType :
      case Magick::TrueColorType : {
        assign(W,H,1,3);
        T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2);
        Magick::PixelPacket *pixels = image.getPixels(0,0,W,H);
        for (ulongT off = (ulongT)W*H; off; --off) {
          *(ptr_r++) = (T)(pixels->red);
          *(ptr_g++) = (T)(pixels->green);
          *(ptr_b++) = (T)(pixels->blue);
          ++pixels;
        }
      } break;
      case Magick::GrayscaleMatteType : {
        assign(W,H,1,2);
        T *ptr_r = data(0,0,0,0), *ptr_a = data(0,0,0,1);
        Magick::PixelPacket *pixels = image.getPixels(0,0,W,H);
        for (ulongT off = (ulongT)W*H; off; --off) {
          *(ptr_r++) = (T)(pixels->red);
          *(ptr_a++) = (T)(pixels->opacity);
          ++pixels;
        }
      } break;
      default : {
        assign(W,H,1,1);
        T *ptr_r = data(0,0,0,0);
        Magick::PixelPacket *pixels = image.getPixels(0,0,W,H);
        for (ulongT off = (ulongT)W*H; off; --off) {
          *(ptr_r++) = (T)(pixels->red);
          ++pixels;
        }
      }
      }
      return *this;
#else
      throw CImgIOException(_cimg_instance
                            "load_magick(): Unable to load file '%s' unless libMagick++ is enabled.",
                            cimg_instance,
                            filename);
#endif
    }

    //! Load image from a file, using Magick++ library \newinstance.
    static CImg<T> get_load_magick(const char *const filename) {
      return CImg<T>().load_magick(filename);
    }

    //! Load an image from a PNG file.
    /**
       This function reads a PNG file and loads its content into the current CImg<T> instance.

       \param filename Path to the PNG file to load, as a C-string.
       \param[out] bits_per_value Number of bits used to store a scalar value in the image file.
       \return Reference to the current image instance, now containing the loaded image.


       \code
       // Example usage:
       CImg<unsigned char> img;
       img.load_png("image.png");
       img.display();
       \endcode

       \warning Throws a CImgIOException if the file does not exist or is not a valid PNG.
    */
    CImg<T>& load_png(const char *const filename, unsigned int *const bits_per_value=0) {
      return _load_png(0,filename,bits_per_value);
    }

    //! Load image from a PNG file \newinstance.
    static CImg<T> get_load_png(const char *const filename, unsigned int *const bits_per_value=0) {
      return CImg<T>().load_png(filename,bits_per_value);
    }

    //! Load image from a PNG file \inplace.
    CImg<T>& load_png(std::FILE *const file, unsigned int *const bits_per_value=0) {
      return _load_png(file,0,bits_per_value);
    }

    //! Load image from a PNG file \newinstance.
    static CImg<T> get_load_png(std::FILE *const file, unsigned int *const bits_per_value=0) {
      return CImg<T>().load_png(file,bits_per_value);
    }

    // (Note: Most of this function has been written by Eric Fausett).
    CImg<T>& _load_png(std::FILE *const file, const char *const filename, unsigned int *const bits_per_value) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_png(): Specified filename is (null).",
                                    cimg_instance);
#ifndef cimg_use_png
      cimg::unused(bits_per_value);
      if (file)
        throw CImgIOException(_cimg_instance
                              "load_png(): Unable to load data from '(FILE*)' unless libpng is enabled.",
                              cimg_instance);

      else return load_other(filename);
#else
      // Open file and check for PNG validity.
#if defined __GNUC__
      const char *volatile nfilename = filename; // Use 'volatile' to avoid (wrong) g++ warning
      std::FILE *volatile nfile = file?file:cimg::fopen(nfilename,"rb");
#else
      const char *nfilename = filename;
      std::FILE *nfile = file?file:cimg::fopen(nfilename,"rb");
#endif
      unsigned char pngCheck[8] = {};
      cimg::fread(pngCheck,8,(std::FILE*)nfile);
      if (png_sig_cmp(pngCheck,0,8)) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_png(): Invalid PNG file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }

      // Setup PNG structures for read.
      png_voidp user_error_ptr = 0;
      png_error_ptr user_error_fn = 0, user_warning_fn = 0;
      png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,user_error_ptr,user_error_fn,user_warning_fn);
      if (!png_ptr) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'png_ptr' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_infop info_ptr = png_create_info_struct(png_ptr);
      if (!info_ptr) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,(png_infopp)0,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'info_ptr' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_infop end_info = png_create_info_struct(png_ptr);
      if (!end_info) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,&info_ptr,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Failed to initialize 'end_info' structure for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }

      // Error handling callback for png file reading.
      if (setjmp(png_jmpbuf(png_ptr))) {
        if (!file) cimg::fclose((std::FILE*)nfile);
        png_destroy_read_struct(&png_ptr, &end_info, (png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Encountered unknown fatal error in libpng for file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_init_io(png_ptr, nfile);
      png_set_sig_bytes(png_ptr, 8);

      // Get PNG Header Info up to data block.
      png_read_info(png_ptr,info_ptr);
      png_uint_32 W, H;
      int bit_depth, color_type, interlace_type;
      bool is_gray = false;
      png_get_IHDR(png_ptr,info_ptr,&W,&H,&bit_depth,&color_type,&interlace_type,(int*)0,(int*)0);
      png_set_interlace_handling(png_ptr);
      if (bits_per_value) *bits_per_value = (unsigned int)bit_depth;

      // Transforms to unify image data.
      if (color_type==PNG_COLOR_TYPE_PALETTE) {
        png_set_palette_to_rgb(png_ptr);
        color_type = PNG_COLOR_TYPE_RGB;
        bit_depth = 8;
      }
      if (color_type==PNG_COLOR_TYPE_GRAY && bit_depth<8) {
        png_set_expand_gray_1_2_4_to_8(png_ptr);
        is_gray = true;
        bit_depth = 8;
      }
      if (png_get_valid(png_ptr,info_ptr,PNG_INFO_tRNS)) {
        png_set_tRNS_to_alpha(png_ptr);
        color_type|=PNG_COLOR_MASK_ALPHA;
      }
      if (color_type==PNG_COLOR_TYPE_GRAY || color_type==PNG_COLOR_TYPE_GRAY_ALPHA) {
        png_set_gray_to_rgb(png_ptr);
        color_type|=PNG_COLOR_MASK_COLOR;
        is_gray = true;
      }
      if (color_type==PNG_COLOR_TYPE_RGB)
        png_set_filler(png_ptr,0xffffU,PNG_FILLER_AFTER);

      png_read_update_info(png_ptr,info_ptr);
      if (bit_depth!=8 && bit_depth!=16) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,&end_info,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Invalid bit depth %u in file '%s'.",
                              cimg_instance,
                              bit_depth,nfilename?nfilename:"(FILE*)");
      }
      const int byte_depth = bit_depth>>3;

      // Allocate memory for image reading.
      png_bytep *const imgData = new png_bytep[H];
      for (unsigned int row = 0; row<H; ++row) imgData[row] = new png_byte[(size_t)byte_depth*4*W];
      png_read_image(png_ptr,imgData);
      png_read_end(png_ptr,end_info);

      // Read pixel data.
      if (color_type!=PNG_COLOR_TYPE_RGB && color_type!=PNG_COLOR_TYPE_RGB_ALPHA) {
        if (!file) cimg::fclose(nfile);
        png_destroy_read_struct(&png_ptr,&end_info,(png_infopp)0);
        throw CImgIOException(_cimg_instance
                              "load_png(): Invalid color coding type %u in file '%s'.",
                              cimg_instance,
                              color_type,nfilename?nfilename:"(FILE*)");
      }
      const bool is_alpha = (color_type==PNG_COLOR_TYPE_RGBA);
      try { assign(W,H,1,(is_gray?1:3) + (is_alpha?1:0)); }
      catch (...) { delete[] imgData; if (!file) cimg::fclose(nfile); throw; }
      T
        *ptr_r = data(0,0,0,0),
        *ptr_g = is_gray?0:data(0,0,0,1),
        *ptr_b = is_gray?0:data(0,0,0,2),
        *ptr_a = !is_alpha?0:data(0,0,0,is_gray?1:3);
      switch (bit_depth) {
      case 8 : {
        cimg_forY(*this,y) {
          const unsigned char *ptrs = (unsigned char*)imgData[y];
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            if (ptr_g) *(ptr_g++) = (T)*(ptrs++); else ++ptrs;
            if (ptr_b) *(ptr_b++) = (T)*(ptrs++); else ++ptrs;
            if (ptr_a) *(ptr_a++) = (T)*(ptrs++); else ++ptrs;
          }
        }
      } break;
      case 16 : {
        cimg_forY(*this,y) {
          const unsigned short *ptrs = (unsigned short*)(imgData[y]);
          if (!cimg::endianness()) cimg::invert_endianness(ptrs,4*_width);
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            if (ptr_g) *(ptr_g++) = (T)*(ptrs++); else ++ptrs;
            if (ptr_b) *(ptr_b++) = (T)*(ptrs++); else ++ptrs;
            if (ptr_a) *(ptr_a++) = (T)*(ptrs++); else ++ptrs;
          }
        }
      } break;
      }
      png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);

      // Deallocate image read memory.
      cimg_forY(*this,n) delete[] imgData[n];
      delete[] imgData;
      if (!file) cimg::fclose(nfile);
      return *this;
#endif
    }

    //! Load image from a PNM file.
    /**
      \param filename Filename, as a C-string.
    **/
    CImg<T>& load_pnm(const char *const filename) {
      return _load_pnm(0,filename);
    }

    //! Load image from a PNM file \newinstance.
    static CImg<T> get_load_pnm(const char *const filename) {
      return CImg<T>().load_pnm(filename);
    }

    //! Load image from a PNM file \inplace.
    CImg<T>& load_pnm(std::FILE *const file) {
      return _load_pnm(file,0);
    }

    //! Load image from a PNM file \newinstance.
    static CImg<T> get_load_pnm(std::FILE *const file) {
      return CImg<T>().load_pnm(file);
    }

    CImg<T>& _load_pnm(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_pnm(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      unsigned int ppm_type, W, H, D = 1, colormax = 255;
      CImg<charT> item(16384,1,1,1,0);
      int err, rval, gval, bval;
      const longT cimg_iobuffer = (longT)24*1024*1024;
      while ((err=std::fscanf(nfile,"%16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
      if (cimg_sscanf(item._data," P%u",&ppm_type)!=1) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pnm(): PNM header not found in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      while ((err=std::fscanf(nfile," %16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
      if ((err=cimg_sscanf(item._data," %u %u %u %u",&W,&H,&D,&colormax))<2) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pnm(): WIDTH and HEIGHT fields undefined in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      if (ppm_type!=1 && ppm_type!=4) {
        if (err==2 || (err==3 && (ppm_type==5 || ppm_type==7 || ppm_type==8 || ppm_type==9))) {
          while ((err=std::fscanf(nfile," %16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
          if (cimg_sscanf(item._data,"%u",&colormax)!=1)
            cimg::warn(_cimg_instance
                       "load_pnm(): COLORMAX field is undefined in file '%s'.",
                       cimg_instance,
                       filename?filename:"(FILE*)");
        } else { colormax = D; D = 1; }
      }
      std::fgetc(nfile);

      if (filename) { // Check that the dimensions specified in file do not exceed the buffer dimensions
        const cimg_int64 siz = cimg::fsize(filename);
        if ((cimg_int64)W*H*D>siz)
          throw CImgIOException(_cimg_instance
                                "load_pnm(): Specified image dimensions in file '%s' exceed file size.",
                                cimg_instance,
                                filename);
      }

      switch (ppm_type) {
      case 1 : { // 2D B&W ASCII
        assign(W,H,1,1);
        T* ptrd = _data;
        cimg_foroff(*this,off) { if (std::fscanf(nfile,"%d",&rval)>0) *(ptrd++) = (T)(rval?0:255); else break; }
      } break;
      case 2 : { // 2D grey ASCII
        assign(W,H,1,1);
        T* ptrd = _data;
        cimg_foroff(*this,off) { if (std::fscanf(nfile,"%d",&rval)>0) *(ptrd++) = (T)rval; else break; }
      } break;
      case 3 : { // 2D color ASCII
        assign(W,H,1,3);
        T *ptrd = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2);
        cimg_forXY(*this,x,y) {
          if (std::fscanf(nfile,"%d %d %d",&rval,&gval,&bval)==3) {
            *(ptrd++) = (T)rval; *(ptr_g++) = (T)gval; *(ptr_b++) = (T)bval;
          } else break;
        }
      } break;
      case 4 : { // 2D b&w binary (support 3D PINK extension)
        CImg<ucharT> raw;
        assign(W,H,D,1);
        T *ptrd = data(0,0,0,0);
        unsigned int w = 0, h = 0, d = 0;
        for (longT to_read = (longT)((W/8 + (W%8?1:0))*H*D); to_read>0; ) {
          raw.assign(std::min(to_read,cimg_iobuffer));
          cimg::fread(raw._data,raw._width,nfile);
          to_read-=raw._width;
          const unsigned char *ptrs = raw._data;
          unsigned char mask = 0, val = 0;
          for (ulongT off = (ulongT)raw._width; off || mask; mask>>=1) {
            if (!mask) { if (off--) val = *(ptrs++); mask = 128; }
            *(ptrd++) = (T)((val&mask)?0:255);
            if (++w==W) { w = 0; mask = 0; if (++h==H) { h = 0; if (++d==D) break; }}
          }
        }
      } break;
      case 5 : case 7 : { // 2D/3D grey binary (support 3D PINK extension)
        if (colormax<256) { // 8 bits
          CImg<ucharT> raw;
          assign(W,H,D,1);
          T *ptrd = data(0,0,0,0);
          for (longT to_read = (longT)size(); to_read>0; ) {
            raw.assign(std::min(to_read,cimg_iobuffer));
            cimg::fread(raw._data,raw._width,nfile);
            to_read-=raw._width;
            const unsigned char *ptrs = raw._data;
            for (ulongT off = (ulongT)raw._width; off; --off) *(ptrd++) = (T)*(ptrs++);
          }
        } else { // 16 bits
          CImg<ushortT> raw;
          assign(W,H,D,1);
          T *ptrd = data(0,0,0,0);
          for (longT to_read = (longT)size(); to_read>0; ) {
            raw.assign(std::min(to_read,cimg_iobuffer/2));
            cimg::fread(raw._data,raw._width,nfile);
            if (!cimg::endianness()) cimg::invert_endianness(raw._data,raw._width);
            to_read-=raw._width;
            const unsigned short *ptrs = raw._data;
            for (ulongT off = (ulongT)raw._width; off; --off) *(ptrd++) = (T)*(ptrs++);
          }
        }
      } break;
      case 6 : { // 2D color binary
        if (colormax<256) { // 8 bits
          CImg<ucharT> raw;
          assign(W,H,1,3);
          T
            *ptr_r = data(0,0,0,0),
            *ptr_g = data(0,0,0,1),
            *ptr_b = data(0,0,0,2);
          for (longT to_read = (longT)size(); to_read>0; ) {
            raw.assign(std::min(to_read,cimg_iobuffer));
            cimg::fread(raw._data,raw._width,nfile);
            to_read-=raw._width;
            const unsigned char *ptrs = raw._data;
            for (ulongT off = (ulongT)raw._width/3; off; --off) {
              *(ptr_r++) = (T)*(ptrs++);
              *(ptr_g++) = (T)*(ptrs++);
              *(ptr_b++) = (T)*(ptrs++);
            }
          }
        } else { // 16 bits
          CImg<ushortT> raw;
          assign(W,H,1,3);
          T
            *ptr_r = data(0,0,0,0),
            *ptr_g = data(0,0,0,1),
            *ptr_b = data(0,0,0,2);
          for (longT to_read = (longT)size(); to_read>0; ) {
            raw.assign(std::min(to_read,cimg_iobuffer/2));
            cimg::fread(raw._data,raw._width,nfile);
            if (!cimg::endianness()) cimg::invert_endianness(raw._data,raw._width);
            to_read-=raw._width;
            const unsigned short *ptrs = raw._data;
            for (ulongT off = (ulongT)raw._width/3; off; --off) {
              *(ptr_r++) = (T)*(ptrs++);
              *(ptr_g++) = (T)*(ptrs++);
              *(ptr_b++) = (T)*(ptrs++);
            }
          }
        }
      } break;
      case 8 : { // 2D/3D grey binary with int32 integers (PINK extension)
        CImg<intT> raw;
        assign(W,H,D,1);
        T *ptrd = data(0,0,0,0);
        for (longT to_read = (longT)size(); to_read>0; ) {
          raw.assign(std::min(to_read,cimg_iobuffer));
          cimg::fread(raw._data,raw._width,nfile);
          to_read-=raw._width;
          const int *ptrs = raw._data;
          for (ulongT off = (ulongT)raw._width; off; --off) *(ptrd++) = (T)*(ptrs++);
        }
      } break;
      case 9 : { // 2D/3D grey binary with float values (PINK extension)
        CImg<floatT> raw;
        assign(W,H,D,1);
        T *ptrd = data(0,0,0,0);
        for (longT to_read = (longT)size(); to_read>0; ) {
          raw.assign(std::min(to_read,cimg_iobuffer));
          cimg::fread(raw._data,raw._width,nfile);
          to_read-=raw._width;
          const float *ptrs = raw._data;
          for (ulongT off = (ulongT)raw._width; off; --off) *(ptrd++) = (T)*(ptrs++);
        }
      } break;
      default :
        assign();
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pnm(): PNM type 'P%d' found, but type is not supported.",
                              cimg_instance,
                              filename?filename:"(FILE*)",ppm_type);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a PFM file.
    /**
      \param filename Filename, as a C-string.
    **/
    CImg<T>& load_pfm(const char *const filename) {
      return _load_pfm(0,filename);
    }

    //! Load image from a PFM file \newinstance.
    static CImg<T> get_load_pfm(const char *const filename) {
      return CImg<T>().load_pfm(filename);
    }

    //! Load image from a PFM file \inplace.
    CImg<T>& load_pfm(std::FILE *const file) {
      return _load_pfm(file,0);
    }

    //! Load image from a PFM file \newinstance.
    static CImg<T> get_load_pfm(std::FILE *const file) {
      return CImg<T>().load_pfm(file);
    }

    CImg<T>& _load_pfm(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_pfm(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      char pfm_type;
      CImg<charT> item(16384,1,1,1,0);
      int W = 0, H = 0, err = 0;
      double scale = 0;
      while ((err=std::fscanf(nfile,"%16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
      if (cimg_sscanf(item._data," P%c",&pfm_type)!=1) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pfm(): PFM header not found in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      while ((err=std::fscanf(nfile," %16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
      if ((err=cimg_sscanf(item._data," %d %d",&W,&H))<2) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pfm(): WIDTH and HEIGHT fields are undefined in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      } else if (W<=0 || H<=0) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pfm(): WIDTH (%d) and HEIGHT (%d) fields are invalid in file '%s'.",
                              cimg_instance,W,H,
                              filename?filename:"(FILE*)");
      }
      if (err==2) {
        while ((err=std::fscanf(nfile," %16383[^\n]",item.data()))!=EOF && (*item=='#' || !err)) std::fgetc(nfile);
        if (cimg_sscanf(item._data,"%lf",&scale)!=1)
          cimg::warn(_cimg_instance
                     "load_pfm(): SCALE field is undefined in file '%s'.",
                     cimg_instance,
                     filename?filename:"(FILE*)");
      }
      std::fgetc(nfile);
      const bool is_color = (pfm_type=='F'), is_inverted = (scale>0)!=cimg::endianness();
      if (is_color) {
        assign(W,H,1,3,(T)0);
        CImg<floatT> buf(3*W);
        T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2);
        cimg_forY(*this,y) {
          cimg::fread(buf._data,3*W,nfile);
          if (is_inverted) cimg::invert_endianness(buf._data,3*W);
          const float *ptrs = buf._data;
          cimg_forX(*this,x) {
            *(ptr_r++) = (T)*(ptrs++);
            *(ptr_g++) = (T)*(ptrs++);
            *(ptr_b++) = (T)*(ptrs++);
          }
        }
      } else {
        assign(W,H,1,1,(T)0);
        CImg<floatT> buf(W);
        T *ptrd = data(0,0,0,0);
        cimg_forY(*this,y) {
          cimg::fread(buf._data,W,nfile);
          if (is_inverted) cimg::invert_endianness(buf._data,W);
          const float *ptrs = buf._data;
          cimg_forX(*this,x) *(ptrd++) = (T)*(ptrs++);
        }
      }
      if (!file) cimg::fclose(nfile);
      return mirror('y'); // Most of the .pfm files are flipped along the y-axis
    }

    //! Load image from a RGB file.
    /**
      \param filename Filename, as a C-string.
      \param dimw Width of the image buffer.
      \param dimh Height of the image buffer.
    **/
    CImg<T>& load_rgb(const char *const filename, const unsigned int dimw, const unsigned int dimh=1) {
      return _load_rgb(0,filename,dimw,dimh);
    }

    //! Load image from a RGB file \newinstance.
    static CImg<T> get_load_rgb(const char *const filename, const unsigned int dimw, const unsigned int dimh=1) {
      return CImg<T>().load_rgb(filename,dimw,dimh);
    }

    //! Load image from a RGB file \inplace.
    CImg<T>& load_rgb(std::FILE *const file, const unsigned int dimw, const unsigned int dimh=1) {
      return _load_rgb(file,0,dimw,dimh);
    }

    //! Load image from a RGB file \newinstance.
    static CImg<T> get_load_rgb(std::FILE *const file, const unsigned int dimw, const unsigned int dimh=1) {
      return CImg<T>().load_rgb(file,dimw,dimh);
    }

    CImg<T>& _load_rgb(std::FILE *const file, const char *const filename,
                       const unsigned int dimw, const unsigned int dimh) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_rgb(): Specified filename is (null).",
                                    cimg_instance);

      if (!dimw || !dimh) return assign();
      const longT cimg_iobuffer = (longT)24*1024*1024;
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      CImg<ucharT> raw;
      assign(dimw,dimh,1,3);
      T
        *ptr_r = data(0,0,0,0),
        *ptr_g = data(0,0,0,1),
        *ptr_b = data(0,0,0,2);
      for (longT to_read = (longT)size(); to_read>0; ) {
        raw.assign(std::min(to_read,cimg_iobuffer));
        cimg::fread(raw._data,raw._width,nfile);
        to_read-=raw._width;
        const unsigned char *ptrs = raw._data;
        for (ulongT off = raw._width/3UL; off; --off) {
          *(ptr_r++) = (T)*(ptrs++);
          *(ptr_g++) = (T)*(ptrs++);
          *(ptr_b++) = (T)*(ptrs++);
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a RGBA file.
    /**
       \param filename Filename, as a C-string.
       \param dimw Width of the image buffer.
       \param dimh Height of the image buffer.
    **/
    CImg<T>& load_rgba(const char *const filename, const unsigned int dimw, const unsigned int dimh=1) {
      return _load_rgba(0,filename,dimw,dimh);
    }

    //! Load image from a RGBA file \newinstance.
    static CImg<T> get_load_rgba(const char *const filename, const unsigned int dimw, const unsigned int dimh=1) {
      return CImg<T>().load_rgba(filename,dimw,dimh);
    }

    //! Load image from a RGBA file \inplace.
    CImg<T>& load_rgba(std::FILE *const file, const unsigned int dimw, const unsigned int dimh=1) {
      return _load_rgba(file,0,dimw,dimh);
    }

    //! Load image from a RGBA file \newinstance.
    static CImg<T> get_load_rgba(std::FILE *const file, const unsigned int dimw, const unsigned int dimh=1) {
      return CImg<T>().load_rgba(file,dimw,dimh);
    }

    CImg<T>& _load_rgba(std::FILE *const file, const char *const filename,
                        const unsigned int dimw, const unsigned int dimh) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_rgba(): Specified filename is (null).",
                                    cimg_instance);

      if (!dimw || !dimh) return assign();
      const longT cimg_iobuffer = (longT)24*1024*1024;
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      CImg<ucharT> raw;
      assign(dimw,dimh,1,4);
      T
        *ptr_r = data(0,0,0,0),
        *ptr_g = data(0,0,0,1),
        *ptr_b = data(0,0,0,2),
        *ptr_a = data(0,0,0,3);
      for (longT to_read = (longT)size(); to_read>0; ) {
        raw.assign(std::min(to_read,cimg_iobuffer));
        cimg::fread(raw._data,raw._width,nfile);
        to_read-=raw._width;
        const unsigned char *ptrs = raw._data;
        for (ulongT off = raw._width/4UL; off; --off) {
          *(ptr_r++) = (T)*(ptrs++);
          *(ptr_g++) = (T)*(ptrs++);
          *(ptr_b++) = (T)*(ptrs++);
          *(ptr_a++) = (T)*(ptrs++);
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a TIFF file.
    /**
       \param filename Filename, as a C-string.
       \param first_frame First frame to read (for multi-pages tiff).
       \param last_frame Last frame to read (for multi-pages tiff).
       \param step_frame Step value of frame reading.
       \param[out] bits_per_value Number of bits used to store a scalar value in the image file.
       \param[out] voxel_size Voxel size, as stored in the filename.
       \param[out] description Description, as stored in the filename.
       \note
       - libtiff support is enabled by defining the precompilation
        directive \c cimg_use_tiff.
       - When libtiff is enabled, 2D and 3D (multipage) several channels per pixel are supported for
        <tt>char,uchar,short,ushort,float</tt> and \c double pixel types.
       - If \c cimg_use_tiff is not defined at compile time the
        function uses CImg<T>& load_other(const char*).
     **/
    CImg<T>& load_tiff(const char *const filename,
                       const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                       const unsigned int step_frame=1, unsigned int *const bits_per_value=0,
                       float *const voxel_size=0, CImg<charT> *const description=0) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_tiff(): Specified filename is (null).",
                                    cimg_instance);

      const unsigned int
        nfirst_frame = first_frame<last_frame?first_frame:last_frame,
        nstep_frame = step_frame?step_frame:1;
      unsigned int nlast_frame = first_frame<last_frame?last_frame:first_frame;

#ifndef cimg_use_tiff
      cimg::unused(bits_per_value,voxel_size,description);
      if (nfirst_frame || nlast_frame!=~0U || nstep_frame>1)
        throw CImgArgumentException(_cimg_instance
                                    "load_tiff(): Unable to read sub-images from file '%s' unless libtiff is enabled.",
                                    cimg_instance,
                                    filename);
      return load_other(filename);
#else
#if cimg_verbosity<3
      TIFFSetWarningHandler(0);
      TIFFSetErrorHandler(0);
#endif
      TIFF *tif = TIFFOpen(filename,"r");
      if (tif) {
        unsigned int nb_images = 0;
        do ++nb_images; while (TIFFReadDirectory(tif));
        if (nfirst_frame>=nb_images || (nlast_frame!=~0U && nlast_frame>=nb_images))
          cimg::warn(_cimg_instance
                     "load_tiff(): File '%s' contains %u image(s) while specified frame range is [%u,%u] (step %u).",
                     cimg_instance,
                     filename,nb_images,nfirst_frame,nlast_frame,nstep_frame);

        if (nfirst_frame>=nb_images) return assign();
        if (nlast_frame>=nb_images) nlast_frame = nb_images - 1;
        TIFFSetDirectory(tif,0);
        CImg<T> frame;
        for (unsigned int l = nfirst_frame; l<=nlast_frame; l+=nstep_frame) {
          frame._load_tiff(tif,l,bits_per_value,voxel_size,description);
          if (l==nfirst_frame)
            assign(frame._width,frame._height,1 + (nlast_frame - nfirst_frame)/nstep_frame,frame._spectrum);
          if (frame._width>_width || frame._height>_height || frame._spectrum>_spectrum)
            resize(std::max(frame._width,_width),
                   std::max(frame._height,_height),-100,
                   std::max(frame._spectrum,_spectrum),0);
          draw_image(0,0,(l - nfirst_frame)/nstep_frame,frame);
        }
        TIFFClose(tif);
      } else throw CImgIOException(_cimg_instance
                                   "load_tiff(): Failed to open file '%s'.",
                                   cimg_instance,
                                   filename);
      return *this;
#endif
    }

    //! Load image from a TIFF file \newinstance.
    static CImg<T> get_load_tiff(const char *const filename,
                                 const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                 const unsigned int step_frame=1, unsigned int *const bits_per_value=0,
                                 float *const voxel_size=0, CImg<charT> *const description=0) {
      return CImg<T>().load_tiff(filename,first_frame,last_frame,step_frame,bits_per_value,voxel_size,description);
    }

    // (Original contribution by Jerome Boulanger).
#ifdef cimg_use_tiff
    template<typename t>
    void _load_tiff_tiled_contig(TIFF *const tif, const cimg_uint16 samplesperpixel,
                                 const cimg_uint32 nx, const cimg_uint32 ny,
                                 const cimg_uint32 tw, const cimg_uint32 th) {
      t *const buf = (t*)_TIFFmalloc(TIFFTileSize(tif));
      if (buf) {
        for (unsigned int row = 0; row<ny; row+=th)
          for (unsigned int col = 0; col<nx; col+=tw) {
            if (TIFFReadTile(tif,buf,col,row,0,0)<0) {
              _TIFFfree(buf); TIFFClose(tif);
              throw CImgIOException(_cimg_instance
                                    "load_tiff(): Invalid tile in file '%s'.",
                                    cimg_instance,
                                    TIFFFileName(tif));
            }
            const t *ptr = buf;
            for (unsigned int rr = row; rr<std::min((unsigned int)(row + th),(unsigned int)ny); ++rr)
              for (unsigned int cc = col; cc<std::min((unsigned int)(col + tw),(unsigned int)nx); ++cc)
                for (unsigned int vv = 0; vv<samplesperpixel; ++vv)
                  (*this)(cc,rr,vv) = (T)(ptr[(rr - row)*th*samplesperpixel + (cc - col)*samplesperpixel + vv]);
          }
        _TIFFfree(buf);
      }
    }

    template<typename t>
    void _load_tiff_tiled_separate(TIFF *const tif, const cimg_uint16 samplesperpixel,
                                   const cimg_uint32 nx, const cimg_uint32 ny,
                                   const cimg_uint32 tw, const cimg_uint32 th) {
      t *const buf = (t*)_TIFFmalloc(TIFFTileSize(tif));
      if (buf) {
        for (unsigned int vv = 0; vv<samplesperpixel; ++vv)
          for (unsigned int row = 0; row<ny; row+=th)
            for (unsigned int col = 0; col<nx; col+=tw) {
              if (TIFFReadTile(tif,buf,col,row,0,vv)<0) {
                _TIFFfree(buf); TIFFClose(tif);
                throw CImgIOException(_cimg_instance
                                      "load_tiff(): Invalid tile in file '%s'.",
                                      cimg_instance,
                                      TIFFFileName(tif));
              }
              const t *ptr = buf;
              for (unsigned int rr = row; rr<std::min((unsigned int)(row + th),(unsigned int)ny); ++rr)
                for (unsigned int cc = col; cc<std::min((unsigned int)(col + tw),(unsigned int)nx); ++cc)
                  (*this)(cc,rr,vv) = (T)*(ptr++);
            }
        _TIFFfree(buf);
      }
    }

    template<typename t>
    void _load_tiff_contig(TIFF *const tif, const cimg_uint16 samplesperpixel,
                           const cimg_uint32 nx, const cimg_uint32 ny) {
      t *const buf = (t*)_TIFFmalloc(TIFFStripSize(tif));
      if (buf) {
        cimg_uint32 row, rowsperstrip = (cimg_uint32)-1;
        TIFFGetField(tif,TIFFTAG_ROWSPERSTRIP,&rowsperstrip);
        for (row = 0; row<ny; row+= rowsperstrip) {
          cimg_uint32 nrow = (row + rowsperstrip>ny?ny - row:rowsperstrip);
          tstrip_t strip = TIFFComputeStrip(tif, row, 0);
          if ((TIFFReadEncodedStrip(tif,strip,buf,-1))<0) {
            _TIFFfree(buf); TIFFClose(tif);
            throw CImgIOException(_cimg_instance
                                  "load_tiff(): Invalid strip in file '%s'.",
                                  cimg_instance,
                                  TIFFFileName(tif));
          }
          const t *ptr = buf;
          for (unsigned int rr = 0; rr<nrow; ++rr)
            for (unsigned int cc = 0; cc<nx; ++cc)
              for (unsigned int vv = 0; vv<samplesperpixel; ++vv) (*this)(cc,row + rr,vv) = (T)*(ptr++);
        }
        _TIFFfree(buf);
      }
    }

    template<typename t>
    void _load_tiff_separate(TIFF *const tif, const cimg_uint16 samplesperpixel,
                             const cimg_uint32 nx, const cimg_uint32 ny) {
      t *buf = (t*)_TIFFmalloc(TIFFStripSize(tif));
      if (buf) {
        cimg_uint32 row, rowsperstrip = (cimg_uint32)-1;
        TIFFGetField(tif,TIFFTAG_ROWSPERSTRIP,&rowsperstrip);
        for (unsigned int vv = 0; vv<samplesperpixel; ++vv)
          for (row = 0; row<ny; row+= rowsperstrip) {
            cimg_uint32 nrow = (row + rowsperstrip>ny?ny - row:rowsperstrip);
            tstrip_t strip = TIFFComputeStrip(tif, row, vv);
            if ((TIFFReadEncodedStrip(tif,strip,buf,-1))<0) {
              _TIFFfree(buf); TIFFClose(tif);
              throw CImgIOException(_cimg_instance
                                    "load_tiff(): Invalid strip in file '%s'.",
                                    cimg_instance,
                                    TIFFFileName(tif));
            }
            const t *ptr = buf;
            for (unsigned int rr = 0;rr<nrow; ++rr)
              for (unsigned int cc = 0; cc<nx; ++cc)
                (*this)(cc,row + rr,vv) = (T)*(ptr++);
          }
        _TIFFfree(buf);
      }
    }

    CImg<T>& _load_tiff(TIFF *const tif, const unsigned int directory, unsigned int *const bits_per_value,
                        float *const voxel_size, CImg<charT> *const description) {
      if (!TIFFSetDirectory(tif,directory)) return assign();
      cimg_uint16 samplesperpixel = 1, bitspersample = 8, photo = 0;
      cimg_uint16 sampleformat = 1;
      cimg_uint32 nx = 1, ny = 1;
      const char *const filename = TIFFFileName(tif);
      const bool is_spp = (bool)TIFFGetField(tif,TIFFTAG_SAMPLESPERPIXEL,&samplesperpixel);
      TIFFGetField(tif,TIFFTAG_IMAGEWIDTH,&nx);
      TIFFGetField(tif,TIFFTAG_IMAGELENGTH,&ny);
      TIFFGetField(tif, TIFFTAG_SAMPLEFORMAT, &sampleformat);
      TIFFGetFieldDefaulted(tif,TIFFTAG_BITSPERSAMPLE,&bitspersample);
      TIFFGetField(tif,TIFFTAG_PHOTOMETRIC,&photo);
      if (bits_per_value) *bits_per_value = (unsigned int)bitspersample;
      if (voxel_size) {
        const char *s_description = 0;
        float vx = 0, vy = 0, vz = 0;
        bool parsed_from_description = false;
        if (TIFFGetField(tif,TIFFTAG_IMAGEDESCRIPTION,&s_description) && s_description) {
          const char *s_desc = std::strstr(s_description,"VX=");
          if (s_desc && cimg_sscanf(s_desc,"VX=%f VY=%f VZ=%f",&vx,&vy,&vz)==3) { // CImg format
            voxel_size[0] = vx; voxel_size[1] = vy; voxel_size[2] = vz;
            parsed_from_description = true;
          }
          s_desc = std::strstr(s_description,"spacing=");
          if (s_desc && cimg_sscanf(s_desc,"spacing=%f",&vz)==1) { // Fiji format
            voxel_size[2] = vz;
          }
        }
        if (!parsed_from_description) {
          TIFFGetField(tif,TIFFTAG_XRESOLUTION,voxel_size);
          TIFFGetField(tif,TIFFTAG_YRESOLUTION,voxel_size + 1);
          voxel_size[0] = 1.f/voxel_size[0];
          voxel_size[1] = 1.f/voxel_size[1];
        }
      }
      if (description) {
        const char *s_description = 0;
        if (TIFFGetField(tif,TIFFTAG_IMAGEDESCRIPTION,&s_description) && s_description)
          CImg<charT>::string(s_description).move_to(*description);
      }
      const unsigned int spectrum = !is_spp || photo>=3?(photo>1?3:1):samplesperpixel;
      assign(nx,ny,1,spectrum);

      if ((photo>=3 && sampleformat==1 &&
           (bitspersample==4 || bitspersample==8) &&
           (samplesperpixel==1 || samplesperpixel==3 || samplesperpixel==4)) ||
          (bitspersample==1 && samplesperpixel==1)) {
        // Special case for unsigned color images.
        cimg_uint32 *const raster = (cimg_uint32*)_TIFFmalloc(nx*ny*sizeof(cimg_uint32));
        if (!raster) {
          _TIFFfree(raster); TIFFClose(tif);
          throw CImgException(_cimg_instance
                              "load_tiff(): Failed to allocate memory (%s) for file '%s'.",
                              cimg_instance,
                              cimg::strbuffersize(nx*ny*sizeof(cimg_uint32)),filename);
        }
        TIFFReadRGBAImage(tif,nx,ny,raster,0);
        switch (spectrum) {
        case 1 :
          cimg_forXY(*this,x,y)
            (*this)(x,y,0) = (T)(float)TIFFGetR(raster[nx*(ny - 1 -y) + x]);
          break;
        case 3 :
          cimg_forXY(*this,x,y) {
            (*this)(x,y,0) = (T)(float)TIFFGetR(raster[nx*(ny - 1 - y) + x]);
            (*this)(x,y,1) = (T)(float)TIFFGetG(raster[nx*(ny - 1 - y) + x]);
            (*this)(x,y,2) = (T)(float)TIFFGetB(raster[nx*(ny - 1 - y) + x]);
          }
          break;
        case 4 :
          cimg_forXY(*this,x,y) {
            (*this)(x,y,0) = (T)(float)TIFFGetR(raster[nx*(ny - 1 - y) + x]);
            (*this)(x,y,1) = (T)(float)TIFFGetG(raster[nx*(ny - 1 - y) + x]);
            (*this)(x,y,2) = (T)(float)TIFFGetB(raster[nx*(ny - 1 - y) + x]);
            (*this)(x,y,3) = (T)(float)TIFFGetA(raster[nx*(ny - 1 - y) + x]);
          }
          break;
        }
        _TIFFfree(raster);
      } else { // Other cases
        cimg_uint16 config;
        TIFFGetField(tif,TIFFTAG_PLANARCONFIG,&config);
        if (TIFFIsTiled(tif)) {
          cimg_uint32 tw = 1, th = 1;
          TIFFGetField(tif,TIFFTAG_TILEWIDTH,&tw);
          TIFFGetField(tif,TIFFTAG_TILELENGTH,&th);
          if (config==PLANARCONFIG_CONTIG) switch (bitspersample) {
            case 8 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_contig<unsigned char>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_contig<signed char>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 16 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_contig<unsigned short>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_contig<short>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 32 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_contig<unsigned int>(tif,samplesperpixel,nx,ny,tw,th);
              else if (sampleformat==SAMPLEFORMAT_INT)
                _load_tiff_tiled_contig<int>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_contig<float>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 64 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_contig<uint64T>(tif,samplesperpixel,nx,ny,tw,th);
              else if (sampleformat==SAMPLEFORMAT_INT)
                _load_tiff_tiled_contig<int64T>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_contig<double>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            } else switch (bitspersample) {
            case 8 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_separate<unsigned char>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_separate<signed char>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 16 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_separate<unsigned short>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_separate<short>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 32 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_separate<unsigned int>(tif,samplesperpixel,nx,ny,tw,th);
              else if (sampleformat==SAMPLEFORMAT_INT)
                _load_tiff_tiled_separate<int>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_separate<float>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            case 64 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_tiled_separate<uint64T>(tif,samplesperpixel,nx,ny,tw,th);
              else if (sampleformat==SAMPLEFORMAT_INT)
                _load_tiff_tiled_separate<int64T>(tif,samplesperpixel,nx,ny,tw,th);
              else _load_tiff_tiled_separate<double>(tif,samplesperpixel,nx,ny,tw,th);
              break;
            }
        } else {
          if (config==PLANARCONFIG_CONTIG) switch (bitspersample) {
            case 8 :
              if (sampleformat==SAMPLEFORMAT_UINT)
                _load_tiff_contig<unsigned char>(tif,samplesperpixel,nx,ny);
              else _load_tiff_contig<signed char>(tif,samplesperpixel,nx,ny);
              break;
            case 16 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_contig<unsigned short>(tif,samplesperpixel,nx,ny);
              else _load_tiff_contig<short>(tif,samplesperpixel,nx,ny);
              break;
            case 32 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_contig<unsigned int>(tif,samplesperpixel,nx,ny);
              else if (sampleformat==SAMPLEFORMAT_INT) _load_tiff_contig<int>(tif,samplesperpixel,nx,ny);
              else _load_tiff_contig<float>(tif,samplesperpixel,nx,ny);
              break;
            case 64 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_contig<uint64T>(tif,samplesperpixel,nx,ny);
              else if (sampleformat==SAMPLEFORMAT_INT) _load_tiff_contig<int64T>(tif,samplesperpixel,nx,ny);
              else _load_tiff_contig<double>(tif,samplesperpixel,nx,ny);
              break;
            } else switch (bitspersample) {
            case 8 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_separate<unsigned char>(tif,samplesperpixel,nx,ny);
              else _load_tiff_separate<signed char>(tif,samplesperpixel,nx,ny);
              break;
            case 16 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_separate<unsigned short>(tif,samplesperpixel,nx,ny);
              else _load_tiff_separate<short>(tif,samplesperpixel,nx,ny);
              break;
            case 32 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_separate<unsigned int>(tif,samplesperpixel,nx,ny);
              else if (sampleformat==SAMPLEFORMAT_INT) _load_tiff_separate<int>(tif,samplesperpixel,nx,ny);
              else _load_tiff_separate<float>(tif,samplesperpixel,nx,ny);
              break;
            case 64 :
              if (sampleformat==SAMPLEFORMAT_UINT) _load_tiff_separate<uint64T>(tif,samplesperpixel,nx,ny);
              else if (sampleformat==SAMPLEFORMAT_INT) _load_tiff_separate<int64T>(tif,samplesperpixel,nx,ny);
              else _load_tiff_separate<double>(tif,samplesperpixel,nx,ny);
              break;
            }
        }
      }
      return *this;
    }
#endif

    //! Load image from a MINC2 file.
    /**
        \param filename Filename, as a C-string.
    **/
    // (Original code by Haz-Edine Assemlal).
    CImg<T>& load_minc2(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_minc2(): Specified filename is (null).",
                                    cimg_instance);
#ifndef cimg_use_minc2
      return load_other(filename);
#else
      minc::minc_1_reader rdr;
      rdr.open(filename);
      assign(rdr.ndim(1)?rdr.ndim(1):1,
             rdr.ndim(2)?rdr.ndim(2):1,
             rdr.ndim(3)?rdr.ndim(3):1,
             rdr.ndim(4)?rdr.ndim(4):1);
      if (pixel_type()==cimg::type<unsigned char>::string())
        rdr.setup_read_byte();
      else if (pixel_type()==cimg::type<int>::string())
        rdr.setup_read_int();
      else if (pixel_type()==cimg::type<double>::string())
        rdr.setup_read_double();
      else
        rdr.setup_read_float();
      minc::load_standard_volume(rdr,this->_data);
      return *this;
#endif
    }

    //! Load image from a MINC2 file \newinstance.
    static CImg<T> get_load_minc2(const char *const filename) {
      return CImg<T>().load_analyze(filename);
    }

    //! Load image from an ANALYZE7.5/NIFTI file.
    /**
       \param filename Filename, as a C-string.
       \param[out] voxel_size Pointer to the three voxel sizes read from the file.
    **/
    CImg<T>& load_analyze(const char *const filename, float *const voxel_size=0) {
      return _load_analyze(0,filename,voxel_size);
    }

    //! Load image from an ANALYZE7.5/NIFTI file \newinstance.
    static CImg<T> get_load_analyze(const char *const filename, float *const voxel_size=0) {
      return CImg<T>().load_analyze(filename,voxel_size);
    }

    //! Load image from an ANALYZE7.5/NIFTI file \inplace.
    CImg<T>& load_analyze(std::FILE *const file, float *const voxel_size=0) {
      return _load_analyze(file,0,voxel_size);
    }

    //! Load image from an ANALYZE7.5/NIFTI file \newinstance.
    static CImg<T> get_load_analyze(std::FILE *const file, float *const voxel_size=0) {
      return CImg<T>().load_analyze(file,voxel_size);
    }

    CImg<T>& _load_analyze(std::FILE *const file, const char *const filename, float *const voxel_size=0) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_analyze(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *nfile_header = 0, *nfile = 0;
      if (!file) {
        CImg<charT> body(1024);
        const char *const ext = cimg::split_filename(filename,body);
        const unsigned int len = (unsigned int)std::strlen(body);
        if (!cimg::strcasecmp(ext,"hdr")) { // File is an Analyze header file
          nfile_header = cimg::fopen(filename,"rb");
          cimg_snprintf(body._data + len,body._width - len,".img");
          nfile = cimg::fopen(body,"rb");
        } else if (!cimg::strcasecmp(ext,"img")) { // File is an Analyze data file
          nfile = cimg::fopen(filename,"rb");
          cimg_snprintf(body._data + len,body._width - len,".hdr");
          nfile_header = cimg::fopen(body,"rb");
        } else nfile_header = nfile = cimg::fopen(filename,"rb"); // File is a Niftii file
      } else nfile_header = nfile = file; // File is a Niftii file
      if (!nfile || !nfile_header)
        throw CImgIOException(_cimg_instance
                              "load_analyze(): Invalid Analyze7.5 or NIFTI header in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");

      // Read header.
      bool endian = false;
      unsigned int header_size;
      cimg::fread(&header_size,1,nfile_header);
      if (header_size>=4096) { endian = true; cimg::invert_endianness(header_size); }
      const ulongT fsiz = file?(ulongT)cimg_max_buf_size:(ulongT)cimg::fsize(filename);
      if (header_size<128 || (ulongT)header_size>fsiz)
        throw CImgIOException(_cimg_instance
                              "load_analyze(): Invalid header size (%u) specified in file '%s'.",
                              cimg_instance,
                              header_size,filename?filename:"(FILE*)");
      CImg<ucharT> _header(header_size);
      unsigned char *const header = _header._data;
      const size_t header_size_read = cimg::fread(header + 4,header_size - 4,nfile_header);
      if (header_size_read!=header_size - 4)
        throw CImgIOException(_cimg_instance
                              "load_analyze(): Cannot read header (of size %u) in file '%s'.",
                              cimg_instance,
                              header_size,filename?filename:"(FILE*)");

      if (!file && nfile_header!=nfile) cimg::fclose(nfile_header);
      if (endian) {
        cimg::invert_endianness((short*)(header + 40),5);
        cimg::invert_endianness((short*)(header + 70),1);
        cimg::invert_endianness((short*)(header + 72),1);
        cimg::invert_endianness((float*)(header + 76),4);
        cimg::invert_endianness((float*)(header + 108),1);
        cimg::invert_endianness((float*)(header + 112),1);
      }

      if (nfile_header==nfile) {
        const unsigned int vox_offset = (unsigned int)*(float*)(header + 108);
        std::fseek(nfile,vox_offset,SEEK_SET);
      }

      unsigned short *dim = (unsigned short*)(header + 40), dimx = 1, dimy = 1, dimz = 1, dimv = 1;
      if (!dim[0])
        cimg::warn(_cimg_instance
                   "load_analyze(): File '%s' defines an image with zero dimensions.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      if (dim[0]>4)
        cimg::warn(_cimg_instance
                   "load_analyze(): File '%s' defines an image with %u dimensions, reading only the 4 first.",
                   cimg_instance,
                   filename?filename:"(FILE*)",dim[0]);

      if (dim[0]>=1) dimx = dim[1];
      if (dim[0]>=2) dimy = dim[2];
      if (dim[0]>=3) dimz = dim[3];
      if (dim[0]>=4) dimv = dim[4];
      float scalefactor = *(float*)(header + 112); if (scalefactor==0) scalefactor = 1;
      const unsigned short datatype = *(unsigned short*)(header + 70);
      if (voxel_size) {
        const float *vsize = (float*)(header + 76);
        voxel_size[0] = vsize[1]; voxel_size[1] = vsize[2]; voxel_size[2] = vsize[3];
      }

      // Read pixel data.
      assign(dimx,dimy,dimz,dimv);
      const size_t pdim = (size_t)dimx*dimy*dimz*dimv;
      switch (datatype) {
      case 2 : {
        CImg<ucharT> _buffer(pdim);
        unsigned char *const buffer = _buffer._data;
        cimg::fread(buffer,pdim,nfile);
        cimg_foroff(*this,off) _data[off] = (T)(buffer[off]*scalefactor);
      } break;
      case 4 : {
        CImg<shortT> _buffer(pdim);
        short *const buffer = _buffer._data;
        cimg::fread(buffer,pdim,nfile);
        if (endian) cimg::invert_endianness(buffer,pdim);
        cimg_foroff(*this,off) _data[off] = (T)(buffer[off]*scalefactor);
      } break;
      case 8 : {
        CImg<intT> _buffer(pdim);
        int *const buffer = _buffer._data;
        cimg::fread(buffer,pdim,nfile);
        if (endian) cimg::invert_endianness(buffer,pdim);
        cimg_foroff(*this,off) _data[off] = (T)(buffer[off]*scalefactor);
      } break;
      case 16 : {
        CImg<floatT> _buffer(pdim);
        float *const buffer = _buffer._data;
        cimg::fread(buffer,pdim,nfile);
        if (endian) cimg::invert_endianness(buffer,pdim);
        cimg_foroff(*this,off) _data[off] = (T)(buffer[off]*scalefactor);
      } break;
      case 64 : {
        CImg<doubleT> _buffer(pdim);
        double *const buffer = _buffer._data;
        cimg::fread(buffer,pdim,nfile);
        if (endian) cimg::invert_endianness(buffer,pdim);
        cimg_foroff(*this,off) _data[off] = (T)(buffer[off]*scalefactor);
      } break;
      default :
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_analyze(): Unable to load datatype %d in file '%s'",
                              cimg_instance,
                              datatype,filename?filename:"(FILE*)");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a .cimg[z] file.
    /**
      \param filename Filename, as a C-string.
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_cimg(const char *const filename, const char axis='z', const float align=0) {
      CImgList<T> list;
      list.load_cimg(filename);
      if (list._width==1) return list[0].move_to(*this);
      return assign(list.get_append(axis,align));
    }

    //! Load image from a .cimg[z] file \newinstance.
    static CImg<T> get_load_cimg(const char *const filename, const char axis='z', const float align=0) {
      return CImg<T>().load_cimg(filename,axis,align);
    }

    //! Load image from a .cimg[z] file \inplace.
    CImg<T>& load_cimg(std::FILE *const file, const char axis='z', const float align=0) {
      CImgList<T> list;
      list.load_cimg(file);
      if (list._width==1) return list[0].move_to(*this);
      return assign(list.get_append(axis,align));
    }

    //! Load image from a .cimg[z] file \newinstance.
    static CImg<T> get_load_cimg(std::FILE *const file, const char axis='z', const float align=0) {
      return CImg<T>().load_cimg(file,axis,align);
    }

    //! Load sub-images of a .cimg file.
    /**
      \param filename Filename, as a C-string.
      \param n0 Starting frame.
      \param n1 Ending frame (~0U for max).
      \param x0 X-coordinate of the starting sub-image vertex.
      \param y0 Y-coordinate of the starting sub-image vertex.
      \param z0 Z-coordinate of the starting sub-image vertex.
      \param c0 C-coordinate of the starting sub-image vertex.
      \param x1 X-coordinate of the ending sub-image vertex (~0U for max).
      \param y1 Y-coordinate of the ending sub-image vertex (~0U for max).
      \param z1 Z-coordinate of the ending sub-image vertex (~0U for max).
      \param c1 C-coordinate of the ending sub-image vertex (~0U for max).
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_cimg(const char *const filename,
                       const unsigned int n0, const unsigned int n1,
                       const unsigned int x0, const unsigned int y0,
                       const unsigned int z0, const unsigned int c0,
                       const unsigned int x1, const unsigned int y1,
                       const unsigned int z1, const unsigned int c1,
                       const char axis='z', const float align=0) {
      CImgList<T> list;
      list.load_cimg(filename,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
      if (list._width==1) return list[0].move_to(*this);
      return assign(list.get_append(axis,align));
    }

    //! Load sub-images of a .cimg file \newinstance.
    static CImg<T> get_load_cimg(const char *const filename,
                                 const unsigned int n0, const unsigned int n1,
                                 const unsigned int x0, const unsigned int y0,
                                 const unsigned int z0, const unsigned int c0,
                                 const unsigned int x1, const unsigned int y1,
                                 const unsigned int z1, const unsigned int c1,
                                 const char axis='z', const float align=0) {
      return CImg<T>().load_cimg(filename,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1,axis,align);
    }

    //! Load sub-images of a .cimg file \inplace.
    CImg<T>& load_cimg(std::FILE *const file,
                       const unsigned int n0, const unsigned int n1,
                       const unsigned int x0, const unsigned int y0,
                       const unsigned int z0, const unsigned int c0,
                       const unsigned int x1, const unsigned int y1,
                       const unsigned int z1, const unsigned int c1,
                       const char axis='z', const float align=0) {
      CImgList<T> list;
      list.load_cimg(file,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
      if (list._width==1) return list[0].move_to(*this);
      return assign(list.get_append(axis,align));
    }

    //! Load sub-images of a .cimg file \newinstance.
    static CImg<T> get_load_cimg(std::FILE *const file,
                                 const unsigned int n0, const unsigned int n1,
                                 const unsigned int x0, const unsigned int y0,
                                 const unsigned int z0, const unsigned int c0,
                                 const unsigned int x1, const unsigned int y1,
                                 const unsigned int z1, const unsigned int c1,
                                 const char axis='z', const float align=0) {
      return CImg<T>().load_cimg(file,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1,axis,align);
    }

    //! Load image from an INRIMAGE-4 file.
    /**
       \param filename Filename, as a C-string.
       \param[out] voxel_size Pointer to the three voxel sizes read from the file.
    **/
    CImg<T>& load_inr(const char *const filename, float *const voxel_size=0) {
      return _load_inr(0,filename,voxel_size);
    }

    //! Load image from an INRIMAGE-4 file \newinstance.
    static CImg<T> get_load_inr(const char *const filename, float *const voxel_size=0) {
      return CImg<T>().load_inr(filename,voxel_size);
    }

    //! Load image from an INRIMAGE-4 file \inplace.
    CImg<T>& load_inr(std::FILE *const file, float *const voxel_size=0) {
      return _load_inr(file,0,voxel_size);
    }

    //! Load image from an INRIMAGE-4 file \newinstance.
    static CImg<T> get_load_inr(std::FILE *const file, float *voxel_size=0) {
      return CImg<T>().load_inr(file,voxel_size);
    }

    static void _load_inr_header(std::FILE *file, int out[8], float *const voxel_size) {
      CImg<charT> item(1024), tmp1(64), tmp2(64);
      *item = *tmp1 = *tmp2 = 0;
      out[0] = std::fscanf(file,"%63s",item._data);
      out[0] = out[1] = out[2] = out[3] = out[5] = 1; out[4] = out[6] = out[7] = -1;
      if (cimg::strncasecmp(item,"#INRIMAGE-4#{",13)!=0)
        throw CImgIOException("CImg<%s>::load_inr(): INRIMAGE-4 header not found.",
                              pixel_type());

      while (std::fscanf(file," %63[^\n]%*c",item._data)!=EOF && std::strncmp(item,"##}",3)) {
        cimg_sscanf(item._data," XDIM%*[^0-9]%d",out);
        cimg_sscanf(item._data," YDIM%*[^0-9]%d",out + 1);
        cimg_sscanf(item._data," ZDIM%*[^0-9]%d",out + 2);
        cimg_sscanf(item._data," VDIM%*[^0-9]%d",out + 3);
        cimg_sscanf(item._data," PIXSIZE%*[^0-9]%d",out + 6);
        if (voxel_size) {
          cimg_sscanf(item._data," VX%*[^0-9.+-]%f",voxel_size);
          cimg_sscanf(item._data," VY%*[^0-9.+-]%f",voxel_size + 1);
          cimg_sscanf(item._data," VZ%*[^0-9.+-]%f",voxel_size + 2);
        }
        if (cimg_sscanf(item._data," CPU%*[ =]%63s",tmp1._data)) out[7] = cimg::strncasecmp(tmp1,"sun",3)?0:1;
        switch (cimg_sscanf(item._data," TYPE%*[ =]%63s %63s",tmp1._data,tmp2._data)) {
        case 0 : break;
        case 2 :
          out[5] = cimg::strncasecmp(tmp1,"unsigned",8)?1:0;
          std::strncpy(tmp1,tmp2,tmp1._width - 1); // Fallthrough
        case 1 :
          if (!cimg::strncasecmp(tmp1,"int",3) || !cimg::strncasecmp(tmp1,"fixed",5))  out[4] = 0;
          if (!cimg::strncasecmp(tmp1,"float",5) || !cimg::strncasecmp(tmp1,"double",6)) out[4] = 1;
          if (!cimg::strncasecmp(tmp1,"packed",6)) out[4] = 2;
          if (out[4]>=0) break; // Fallthrough
        default :
          throw CImgIOException("CImg<%s>::load_inr(): Invalid pixel type '%s' defined in header.",
                                pixel_type(),
                                tmp2._data);
        }
      }
      if (out[0]<0 || out[1]<0 || out[2]<0 || out[3]<0)
        throw CImgIOException("CImg<%s>::load_inr(): Invalid dimensions (%d,%d,%d,%d) defined in header.",
                              pixel_type(),
                              out[0],out[1],out[2],out[3]);
      if (out[4]<0 || out[5]<0)
        throw CImgIOException("CImg<%s>::load_inr(): Incomplete pixel type defined in header.",
                              pixel_type());
      if (out[6]<0)
        throw CImgIOException("CImg<%s>::load_inr(): Incomplete PIXSIZE field defined in header.",
                              pixel_type());
      if (out[7]<0)
        throw CImgIOException("CImg<%s>::load_inr(): Big/Little Endian coding type undefined in header.",
                              pixel_type());
    }

    CImg<T>& _load_inr(std::FILE *const file, const char *const filename, float *const voxel_size) {
#define _cimg_load_inr_case(Tf,sign,pixsize,Ts) \
     if (!loaded && fopt[6]==pixsize && fopt[4]==Tf && fopt[5]==sign) { \
        Ts *xval, *const val = new Ts[(size_t)fopt[0]*fopt[3]]; \
        cimg_forYZ(*this,y,z) { \
            cimg::fread(val,fopt[0]*fopt[3],nfile); \
            if (fopt[7]!=endian) cimg::invert_endianness(val,fopt[0]*fopt[3]); \
            xval = val; cimg_forX(*this,x) cimg_forC(*this,c) (*this)(x,y,z,c) = (T)*(xval++); \
          } \
        delete[] val; \
        loaded = true; \
      }

      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_inr(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      int fopt[8], endian = cimg::endianness()?1:0;
      bool loaded = false;
      if (voxel_size) voxel_size[0] = voxel_size[1] = voxel_size[2] = 1;
      _load_inr_header(nfile,fopt,voxel_size);
      assign(fopt[0],fopt[1],fopt[2],fopt[3]);
      _cimg_load_inr_case(0,0,8,unsigned char);
      _cimg_load_inr_case(0,1,8,char);
      _cimg_load_inr_case(0,0,16,unsigned short);
      _cimg_load_inr_case(0,1,16,short);
      _cimg_load_inr_case(0,0,32,unsigned int);
      _cimg_load_inr_case(0,1,32,int);
      _cimg_load_inr_case(1,0,32,float);
      _cimg_load_inr_case(1,1,32,float);
      _cimg_load_inr_case(1,0,64,double);
      _cimg_load_inr_case(1,1,64,double);
      if (!loaded) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_inr(): Unknown pixel type defined in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a EXR file.
    /**
      \param filename Filename, as a C-string.
    **/
    CImg<T>& load_exr(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_exr(): Specified filename is (null).",
                                    cimg_instance);
#if defined(cimg_use_openexr)
      Imf::RgbaInputFile file(filename);
      Imath::Box2i dw = file.dataWindow();
      const int
        inwidth = dw.max.x - dw.min.x + 1,
        inheight = dw.max.y - dw.min.y + 1;
      Imf::Array2D<Imf::Rgba> pixels;
      pixels.resizeErase(inheight,inwidth);
      file.setFrameBuffer(&pixels[0][0] - dw.min.x - dw.min.y*inwidth, 1, inwidth);
      file.readPixels(dw.min.y, dw.max.y);
      assign(inwidth,inheight,1,4);
      T *ptr_r = data(0,0,0,0), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2), *ptr_a = data(0,0,0,3);
      cimg_forXY(*this,x,y) {
        *(ptr_r++) = (T)pixels[y][x].r;
        *(ptr_g++) = (T)pixels[y][x].g;
        *(ptr_b++) = (T)pixels[y][x].b;
        *(ptr_a++) = (T)pixels[y][x].a;
      }
      return *this;
#elif defined(cimg_use_tinyexr)
      float *res;
      const char *err = 0;
      int width = 0, height = 0;
      const int ret = LoadEXR(&res,&width,&height,filename,&err);
      if (ret) throw CImgIOException(_cimg_instance
                                     "load_exr(): Unable to load EXR file '%s'.",
                                     cimg_instance,filename);
      CImg<floatT>(res,4,width,height,1,true).get_permute_axes("yzcx").move_to(*this);
      std::free(res);
      return *this;
#else
      return load_other(filename);
#endif
    }

    //! Load image from a EXR file \newinstance.
    static CImg<T> get_load_exr(const char *const filename) {
      return CImg<T>().load_exr(filename);
    }

    //! Load image from a PANDORE-5 file.
    /**
      \param filename Filename, as a C-string.
    **/
    CImg<T>& load_pandore(const char *const filename) {
      return _load_pandore(0,filename);
    }

    //! Load image from a PANDORE-5 file \newinstance.
    static CImg<T> get_load_pandore(const char *const filename) {
      return CImg<T>().load_pandore(filename);
    }

    //! Load image from a PANDORE-5 file \inplace.
    CImg<T>& load_pandore(std::FILE *const file) {
      return _load_pandore(file,0);
    }

    //! Load image from a PANDORE-5 file \newinstance.
    static CImg<T> get_load_pandore(std::FILE *const file) {
      return CImg<T>().load_pandore(file);
    }

    CImg<T>& _load_pandore(std::FILE *const file, const char *const filename) {
#define __cimg_load_pandore_case(nbdim,nwidth,nheight,ndepth,ndim,stype) \
        cimg::fread(dims,nbdim,nfile); \
        if (endian) cimg::invert_endianness(dims,nbdim); \
        if ((ulongT)nwidth*nheight*ndepth*ndim>fsiz) \
          throw CImgIOException(_cimg_instance \
                                "load_pandore(): File size %lu for filename '%s' does not match "\
                                "encoded image dimensions (%d,%d,%d,%d).",\
                                cimg_instance,\
                                (long)fsiz,filename?filename:"(FILE*)",\
                                (int)nwidth,(int)nheight,(int)ndepth,(int)ndim); \
        assign(nwidth,nheight,ndepth,ndim); \
        const ulongT siz = size(); \
        CImg<stype> _buffer(_width,_height,_depth,_spectrum); \
        stype *buffer = _buffer._data; \
        cimg::fread(buffer,siz,nfile); \
        if (endian) cimg::invert_endianness(buffer,siz); \
        T *ptrd = _data; \
        cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);

#define _cimg_load_pandore_case(nbdim,nwidth,nheight,ndepth,dim,stype1,stype2,stype3,ltype) { \
        if (sizeof(stype1)==ltype) { __cimg_load_pandore_case(nbdim,nwidth,nheight,ndepth,dim,stype1); } \
        else if (sizeof(stype2)==ltype) { __cimg_load_pandore_case(nbdim,nwidth,nheight,ndepth,dim,stype2); } \
        else if (sizeof(stype3)==ltype) { __cimg_load_pandore_case(nbdim,nwidth,nheight,ndepth,dim,stype3); } \
        else throw CImgIOException(_cimg_instance \
                                   "load_pandore(): Unknown pixel datatype in file '%s'.", \
                                   cimg_instance, \
                                   filename?filename:"(FILE*)"); }
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_pandore(): Specified filename is (null).",
                                    cimg_instance);

      const ulongT fsiz = file?(ulongT)cimg_max_buf_size:(ulongT)cimg::fsize(filename);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      CImg<charT> header(32);
      cimg::fread(header._data,12,nfile);
      if (cimg::strncasecmp("PANDORE",header,7)) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pandore(): PANDORE header not found in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      unsigned int imageid, dims[8] = {};
      int ptbuf[4] = {};
      cimg::fread(&imageid,1,nfile);
      const bool endian = imageid>255;
      if (endian) cimg::invert_endianness(imageid);
      cimg::fread(header._data,20,nfile);

      switch (imageid) {
      case 2 : _cimg_load_pandore_case(2,dims[1],1,1,1,ucharT,ucharT,ucharT,1); break;
      case 3 : _cimg_load_pandore_case(2,dims[1],1,1,1,longT,intT,shortT,4); break;
      case 4 : _cimg_load_pandore_case(2,dims[1],1,1,1,doubleT,floatT,floatT,4); break;
      case 5 : _cimg_load_pandore_case(3,dims[2],dims[1],1,1,ucharT,ucharT,ucharT,1); break;
      case 6 : _cimg_load_pandore_case(3,dims[2],dims[1],1,1,longT,intT,shortT,4); break;
      case 7 : _cimg_load_pandore_case(3,dims[2],dims[1],1,1,doubleT,floatT,floatT,4); break;
      case 8 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],1,ucharT,ucharT,ucharT,1); break;
      case 9 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],1,longT,intT,shortT,4); break;
      case 10 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],1,doubleT,floatT,floatT,4); break;
      case 11 : { // Region 1D
        cimg::fread(dims,3,nfile);
        if (endian) cimg::invert_endianness(dims,3);
        assign(dims[1],1,1,1);
        const ulongT siz = size();
        if (dims[2]<256) {
          CImg<ucharT> _buffer(_width,_height,_depth,_spectrum);
          unsigned char *buffer = _buffer._data;
          cimg::fread(buffer,siz,nfile);
          T *ptrd = _data;
          cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
        } else {
          if (dims[2]<65536) {
            CImg<ushortT> _buffer(_width,_height,_depth,_spectrum);
            unsigned short *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          } else {
            CImg<uintT> _buffer(_width,_height,_depth,_spectrum);
            unsigned int *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          }
        }
      }
        break;
      case 12 : { // Region 2D
        cimg::fread(dims,4,nfile);
        if (endian) cimg::invert_endianness(dims,4);
        assign(dims[2],dims[1],1,1);
        const ulongT siz = size();
        if (dims[3]<256) {
          CImg<ucharT> _buffer(_width,_height,_depth,_spectrum);
          unsigned char *buffer = _buffer._data;
          cimg::fread(buffer,siz,nfile);
          T *ptrd = _data;
          cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
        } else {
          if (dims[3]<65536) {
            CImg<ushortT> _buffer(_width,_height,_depth,_spectrum);
            unsigned short *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          } else {
            CImg<uintT> _buffer(_width,_height,_depth,_spectrum);
            unsigned int *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          }
        }
      }
        break;
      case 13 : { // Region 3D
        cimg::fread(dims,5,nfile);
        if (endian) cimg::invert_endianness(dims,5);
        assign(dims[3],dims[2],dims[1],1);
        const ulongT siz = size();
        if (dims[4]<256) {
          CImg<ucharT> _buffer(_width,_height,_depth,_spectrum);
          unsigned char *buffer = _buffer._data;
          cimg::fread(buffer,siz,nfile);
          T *ptrd = _data;
          cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
        } else {
          if (dims[4]<65536) {
            CImg<ushortT> _buffer(_width,_height,_depth,_spectrum);
            unsigned short *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          } else {
            CImg<uintT> _buffer(_width,_height,_depth,_spectrum);
            unsigned int *buffer = _buffer._data;
            cimg::fread(buffer,siz,nfile);
            if (endian) cimg::invert_endianness(buffer,siz);
            T *ptrd = _data;
            cimg_foroff(*this,off) *(ptrd++) = (T)*(buffer++);
          }
        }
      }
        break;
      case 16 : _cimg_load_pandore_case(4,dims[2],dims[1],1,3,ucharT,ucharT,ucharT,1); break;
      case 17 : _cimg_load_pandore_case(4,dims[2],dims[1],1,3,longT,intT,shortT,4); break;
      case 18 : _cimg_load_pandore_case(4,dims[2],dims[1],1,3,doubleT,floatT,floatT,4); break;
      case 19 : _cimg_load_pandore_case(5,dims[3],dims[2],dims[1],3,ucharT,ucharT,ucharT,1); break;
      case 20 : _cimg_load_pandore_case(5,dims[3],dims[2],dims[1],3,longT,intT,shortT,4); break;
      case 21 : _cimg_load_pandore_case(5,dims[3],dims[2],dims[1],3,doubleT,floatT,floatT,4); break;
      case 22 : _cimg_load_pandore_case(2,dims[1],1,1,dims[0],ucharT,ucharT,ucharT,1); break;
      case 23 : _cimg_load_pandore_case(2,dims[1],1,1,dims[0],longT,intT,shortT,4); break;
      case 24 : _cimg_load_pandore_case(2,dims[1],1,1,dims[0],ulongT,uintT,ushortT,4); break;
      case 25 : _cimg_load_pandore_case(2,dims[1],1,1,dims[0],doubleT,floatT,floatT,4); break;
      case 26 : _cimg_load_pandore_case(3,dims[2],dims[1],1,dims[0],ucharT,ucharT,ucharT,1); break;
      case 27 : _cimg_load_pandore_case(3,dims[2],dims[1],1,dims[0],longT,intT,shortT,4); break;
      case 28 : _cimg_load_pandore_case(3,dims[2],dims[1],1,dims[0],ulongT,uintT,ushortT,4); break;
      case 29 : _cimg_load_pandore_case(3,dims[2],dims[1],1,dims[0],doubleT,floatT,floatT,4); break;
      case 30 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],dims[0],ucharT,ucharT,ucharT,1);
        break;
      case 31 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],dims[0],longT,intT,shortT,4); break;
      case 32 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],dims[0],ulongT,uintT,ushortT,4);
        break;
      case 33 : _cimg_load_pandore_case(4,dims[3],dims[2],dims[1],dims[0],doubleT,floatT,floatT,4); break;
      case 34 : { // Points 1D
        cimg::fread(ptbuf,1,nfile);
        if (endian) cimg::invert_endianness(ptbuf,1);
        assign(1); (*this)(0) = (T)ptbuf[0];
      } break;
      case 35 : { // Points 2D
        cimg::fread(ptbuf,2,nfile);
        if (endian) cimg::invert_endianness(ptbuf,2);
        assign(2); (*this)(0) = (T)ptbuf[1]; (*this)(1) = (T)ptbuf[0];
      } break;
      case 36 : { // Points 3D
        cimg::fread(ptbuf,3,nfile);
        if (endian) cimg::invert_endianness(ptbuf,3);
        assign(3); (*this)(0) = (T)ptbuf[2]; (*this)(1) = (T)ptbuf[1]; (*this)(2) = (T)ptbuf[0];
      } break;
      default :
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_pandore(): Unable to load data with ID_type %u in file '%s'.",
                              cimg_instance,
                              imageid,filename?filename:"(FILE*)");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image from a PAR-REC (Philips) file.
    /**
      \param filename Filename, as a C-string.
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_parrec(const char *const filename, const char axis='c', const float align=0) {
      CImgList<T> list;
      list.load_parrec(filename);
      if (list._width==1) return list[0].move_to(*this);
      return assign(list.get_append(axis,align));
    }

    //! Load image from a PAR-REC (Philips) file \newinstance.
    static CImg<T> get_load_parrec(const char *const filename, const char axis='c', const float align=0) {
      return CImg<T>().load_parrec(filename,axis,align);
    }

    //! Load image from a raw binary file.
    /**
      \param filename Filename, as a C-string.
      \param size_x Width of the image buffer.
      \param size_y Height of the image buffer.
      \param size_z Depth of the image buffer.
      \param size_c Spectrum of the image buffer.
      \param is_multiplexed Indicates whether the image values are multiplexed along the C-axis.
      \param invert_endianness Indicates whether the endianness of the image buffer must be inverted.
      \param offset Starting offset of the read in the specified file.
    **/
    CImg<T>& load_raw(const char *const filename,
                      const unsigned int size_x=0, const unsigned int size_y=1,
                      const unsigned int size_z=1, const unsigned int size_c=1,
                      const bool is_multiplexed=false, const bool invert_endianness=false,
                      const ulongT offset=0) {
      return _load_raw(0,filename,size_x,size_y,size_z,size_c,is_multiplexed,invert_endianness,offset);
    }

    //! Load image from a raw binary file \newinstance.
    static CImg<T> get_load_raw(const char *const filename,
                                const unsigned int size_x=0, const unsigned int size_y=1,
                                const unsigned int size_z=1, const unsigned int size_c=1,
                                const bool is_multiplexed=false, const bool invert_endianness=false,
                                const ulongT offset=0) {
      return CImg<T>().load_raw(filename,size_x,size_y,size_z,size_c,is_multiplexed,invert_endianness,offset);
    }

    //! Load image from a raw binary file \inplace.
    CImg<T>& load_raw(std::FILE *const file,
                      const unsigned int size_x=0, const unsigned int size_y=1,
                      const unsigned int size_z=1, const unsigned int size_c=1,
                      const bool is_multiplexed=false, const bool invert_endianness=false,
                      const ulongT offset=0) {
      return _load_raw(file,0,size_x,size_y,size_z,size_c,is_multiplexed,invert_endianness,offset);
    }

    //! Load image from a raw binary file \newinstance.
    static CImg<T> get_load_raw(std::FILE *const file,
                                const unsigned int size_x=0, const unsigned int size_y=1,
                                const unsigned int size_z=1, const unsigned int size_c=1,
                                const bool is_multiplexed=false, const bool invert_endianness=false,
                                const ulongT offset=0) {
      return CImg<T>().load_raw(file,size_x,size_y,size_z,size_c,is_multiplexed,invert_endianness,offset);
    }

    CImg<T>& _load_raw(std::FILE *const file, const char *const filename,
                       const unsigned int size_x, const unsigned int size_y,
                       const unsigned int size_z, const unsigned int size_c,
                       const bool is_multiplexed, const bool invert_endianness,
                       const ulongT offset) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_raw(): Specified filename is (null).",
                                    cimg_instance);
      if (cimg::is_directory(filename))
        throw CImgArgumentException(_cimg_instance
                                    "load_raw(): Specified filename '%s' is a directory.",
                                    cimg_instance,filename);
      const bool is_bool = pixel_type()==cimg::type<bool>::string();
      ulongT siz = (ulongT)size_x*size_y*size_z*size_c;
      unsigned int
        _size_x = size_x,
        _size_y = size_y,
        _size_z = size_z,
        _size_c = size_c;
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      if (!siz) { // Retrieve file size
        const longT fpos = cimg::ftell(nfile);
        if (fpos<0) throw CImgArgumentException(_cimg_instance
                                                "load_raw(): Cannot determine size of input file '%s'.",
                                                cimg_instance,filename?filename:"(FILE*)");
        cimg::fseek(nfile,0,SEEK_END);
        siz = (ulongT)cimg::ftell(nfile);
        if (!is_bool) { siz/=sizeof(T); _size_y = (unsigned int)siz; }
        else _size_y = (unsigned int)(siz*8);
        _size_x = _size_z = _size_c = 1;
        cimg::fseek(nfile,fpos,SEEK_SET);
      }
      cimg::fseek(nfile,(longT)offset,SEEK_SET);
      assign(_size_x,_size_y,_size_z,_size_c,0);

      if (is_bool) { // Boolean data (bitwise)
        CImg<ucharT> _buffer(siz);
        unsigned char *const buffer = _buffer._data;
        cimg::fread(buffer,siz,nfile);
        _uchar2bool(buffer,siz,is_multiplexed);
      } else { // Non-boolean data
        if (siz && (!is_multiplexed || size_c==1)) { // Non-multiplexed
          cimg::fread(_data,siz,nfile);
          if (invert_endianness) cimg::invert_endianness(_data,siz);
        } else if (siz) { // Multiplexed
          CImg<T> buf(1,1,1,_size_c);
          cimg_forXYZ(*this,x,y,z) {
            cimg::fread(buf._data,_size_c,nfile);
            if (invert_endianness) cimg::invert_endianness(buf._data,_size_c);
            set_vector_at(buf,x,y,z);
          }
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load image sequence from a YUV file.
    /**
      \param filename Filename, as a C-string.
      \param size_x Width of the frames.
      \param size_y Height of the frames.
      \param chroma_subsampling Type of chroma subsampling. Can be <tt>{ 420 | 422 | 444 }</tt>.
      \param first_frame Index of the first frame to read.
      \param last_frame Index of the last frame to read.
      \param step_frame Step value for frame reading.
      \param yuv2rgb Indicates whether the YUV to RGB transform must be applied.
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
    **/
    CImg<T>& load_yuv(const char *const filename,
                      const unsigned int size_x, const unsigned int size_y=1,
                      const unsigned int chroma_subsampling=444,
                      const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                      const unsigned int step_frame=1, const bool yuv2rgb=true, const char axis='z') {
      return get_load_yuv(filename,size_x,size_y,chroma_subsampling,
                          first_frame,last_frame,step_frame,yuv2rgb,axis).move_to(*this);
    }

    //! Load image sequence from a YUV file \newinstance.
    static CImg<T> get_load_yuv(const char *const filename,
                                const unsigned int size_x, const unsigned int size_y=1,
                                const unsigned int chroma_subsampling=444,
                                const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                const unsigned int step_frame=1, const bool yuv2rgb=true, const char axis='z') {
      return CImgList<T>().load_yuv(filename,size_x,size_y,chroma_subsampling,
                                    first_frame,last_frame,step_frame,yuv2rgb).get_append(axis);
    }

    //! Load image sequence from a YUV file \inplace.
    CImg<T>& load_yuv(std::FILE *const file,
                      const unsigned int size_x, const unsigned int size_y=1,
                      const unsigned int chroma_subsampling=444,
                      const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                      const unsigned int step_frame=1, const bool yuv2rgb=true, const char axis='z') {
      return get_load_yuv(file,size_x,size_y,chroma_subsampling,
                          first_frame,last_frame,step_frame,yuv2rgb,axis).move_to(*this);
    }

    //! Load image sequence from a YUV file \newinstance.
    static CImg<T> get_load_yuv(std::FILE *const file,
                                const unsigned int size_x, const unsigned int size_y=1,
                                const unsigned int chroma_subsampling=444,
                                const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                const unsigned int step_frame=1, const bool yuv2rgb=true, const char axis='z') {
      return CImgList<T>().load_yuv(file,size_x,size_y,chroma_subsampling,
                                    first_frame,last_frame,step_frame,yuv2rgb).get_append(axis);
    }

    //! Load 3D object from a .OFF file.
    /**
        \param[out] primitives Primitives data of the 3D object.
        \param[out] colors Colors data of the 3D object.
        \param filename Filename, as a C-string.
    **/
    template<typename tf, typename tc>
    CImg<T>& load_off(CImgList<tf>& primitives, CImgList<tc>& colors, const char *const filename) {
      return _load_off(primitives,colors,0,filename);
    }

    //! Load 3D object from a .OFF file \newinstance.
    template<typename tf, typename tc>
    static CImg<T> get_load_off(CImgList<tf>& primitives, CImgList<tc>& colors, const char *const filename) {
      return CImg<T>().load_off(primitives,colors,filename);
    }

    //! Load 3D object from a .OFF file \inplace.
    template<typename tf, typename tc>
    CImg<T>& load_off(CImgList<tf>& primitives, CImgList<tc>& colors, std::FILE *const file) {
      return _load_off(primitives,colors,file,0);
    }

    //! Load 3D object from a .OFF file \newinstance.
    template<typename tf, typename tc>
    static CImg<T> get_load_off(CImgList<tf>& primitives, CImgList<tc>& colors, std::FILE *const file) {
      return CImg<T>().load_off(primitives,colors,file);
    }

    template<typename tf, typename tc>
    CImg<T>& _load_off(CImgList<tf>& primitives, CImgList<tc>& colors,
                       std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_off(): Specified filename is (null).",
                                    cimg_instance);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"r");
      unsigned int nb_points = 0, nb_primitives = 0, nb_read = 0;
      CImg<charT> line(256); *line = 0;
      int err;

      // Skip comments, and read magic string OFF.
      do { err = std::fscanf(nfile,"%255[^\n] ",line._data); } while (!err || (err==1 && *line=='#'));
      if (cimg::strncasecmp(line,"OFF",3) && cimg::strncasecmp(line,"COFF",4)) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_off(): OFF header not found in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }
      do { err = std::fscanf(nfile,"%255[^\n] ",line._data); } while (!err || (err==1 && *line=='#'));
      if ((err = cimg_sscanf(line._data,"%u%u%*[^\n] ",&nb_points,&nb_primitives))!=2) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "load_off(): Invalid number of vertices or primitives specified in file '%s'.",
                              cimg_instance,
                              filename?filename:"(FILE*)");
      }

      // Read points data.
      assign(nb_points,3);
      float X = 0, Y = 0, Z = 0;
      cimg_forX(*this,l) {
        do { err = std::fscanf(nfile,"%255[^\n] ",line._data); } while (!err || (err==1 && *line=='#'));
        if ((err = cimg_sscanf(line._data,"%f%f%f%*[^\n] ",&X,&Y,&Z))!=3) {
          if (!file) cimg::fclose(nfile);
          throw CImgIOException(_cimg_instance
                                "load_off(): Failed to read vertex %u/%u in file '%s'.",
                                cimg_instance,
                                l + 1,nb_points,filename?filename:"(FILE*)");
        }
        (*this)(l,0) = (T)X; (*this)(l,1) = (T)Y; (*this)(l,2) = (T)Z;
      }

      // Read primitive data.
      primitives.assign();
      colors.assign();
      bool stop_flag = false;
      while (!stop_flag) {
        float c0 = 0.7f, c1 = 0.7f, c2 = 0.7f;
        unsigned int prim = 0, i0 = 0, i1 = 0, i2 = 0, i3 = 0, i4 = 0, i5 = 0, i6 = 0, i7 = 0;
        *line = 0;
        if ((err = std::fscanf(nfile,"%u",&prim))!=1) stop_flag = true;
        else {
          ++nb_read;
          switch (prim) {
          case 1 : {
            if ((err = std::fscanf(nfile,"%u%255[^\n] ",&i0,line._data))<2) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0).move_to(primitives);
              CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)).move_to(colors);
            }
          } break;
          case 2 : {
            if ((err = std::fscanf(nfile,"%u%u%255[^\n] ",&i0,&i1,line._data))<2) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i1).move_to(primitives);
              CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)).move_to(colors);
            }
          } break;
          case 3 : {
            if ((err = std::fscanf(nfile,"%u%u%u%255[^\n] ",&i0,&i1,&i2,line._data))<3) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i2,i1).move_to(primitives);
              CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)).move_to(colors);
            }
          } break;
          case 4 : {
            if ((err = std::fscanf(nfile,"%u%u%u%u%255[^\n] ",&i0,&i1,&i2,&i3,line._data))<4) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i3,i2,i1).move_to(primitives);
              CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)).move_to(colors);
            }
          } break;
          case 5 : {
            if ((err = std::fscanf(nfile,"%u%u%u%u%u%255[^\n] ",&i0,&i1,&i2,&i3,&i4,line._data))<5) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i3,i2,i1).move_to(primitives);
              CImg<tf>::vector(i0,i4,i3).move_to(primitives);
              colors.insert(2,CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)));
              ++nb_primitives;
            }
          } break;
          case 6 : {
            if ((err = std::fscanf(nfile,"%u%u%u%u%u%u%255[^\n] ",&i0,&i1,&i2,&i3,&i4,&i5,line._data))<6) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i3,i2,i1).move_to(primitives);
              CImg<tf>::vector(i0,i5,i4,i3).move_to(primitives);
              colors.insert(2,CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)));
              ++nb_primitives;
            }
          } break;
          case 7 : {
            if ((err = std::fscanf(nfile,"%u%u%u%u%u%u%u%255[^\n] ",&i0,&i1,&i2,&i3,&i4,&i5,&i6,line._data))<7) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i4,i3,i1).move_to(primitives);
              CImg<tf>::vector(i0,i6,i5,i4).move_to(primitives);
              CImg<tf>::vector(i3,i2,i1).move_to(primitives);
              colors.insert(3,CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)));
              ++(++nb_primitives);
            }
          } break;
          case 8 : {
            if ((err = std::fscanf(nfile,"%u%u%u%u%u%u%u%u%255[^\n] ",&i0,&i1,&i2,&i3,&i4,&i5,&i6,&i7,line._data))<7) {
              cimg::warn(_cimg_instance
                         "load_off(): Failed to read primitive %u/%u from file '%s'.",
                         cimg_instance,
                         nb_read,nb_primitives,filename?filename:"(FILE*)");

              err = std::fscanf(nfile,"%*[^\n] ");
            } else {
              err = cimg_sscanf(line._data,"%f%f%f",&c0,&c1,&c2);
              CImg<tf>::vector(i0,i3,i2,i1).move_to(primitives);
              CImg<tf>::vector(i0,i5,i4,i3).move_to(primitives);
              CImg<tf>::vector(i0,i7,i6,i5).move_to(primitives);
              colors.insert(3,CImg<tc>::vector((tc)(c0*255),(tc)(c1*255),(tc)(c2*255)));
              ++(++nb_primitives);
            }
          } break;
          default :
            cimg::warn(_cimg_instance
                       "load_off(): Failed to read primitive %u/%u (%u vertices) from file '%s'.",
                       cimg_instance,
                       nb_read,nb_primitives,prim,filename?filename:"(FILE*)");

            err = std::fscanf(nfile,"%*[^\n] ");
          }
        }
      }
      if (!file) cimg::fclose(nfile);
      if (primitives._width!=nb_primitives)
        cimg::warn(_cimg_instance
                   "load_off(): Only %u/%u primitives read from file '%s'.",
                   cimg_instance,
                   primitives._width,nb_primitives,filename?filename:"(FILE*)");
      return *this;
    }

    //! Load image sequence from a video file, using OpenCV library.
    /**
      \param filename Filename, as a C-string.
      \param first_frame Index of the first frame to read.
      \param last_frame Index of the last frame to read.
      \param step_frame Step value for frame reading.
      \param axis Alignment axis.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_video(const char *const filename,
                        const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                        const unsigned int step_frame=1,
                        const char axis='z', const float align=0) {
      return get_load_video(filename,first_frame,last_frame,step_frame,axis,align).move_to(*this);
    }

    //! Load image sequence from a video file, using OpenCV library \newinstance.
    static CImg<T> get_load_video(const char *const filename,
                                  const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                  const unsigned int step_frame=1,
                                  const char axis='z', const float align=0) {
      return CImgList<T>().load_video(filename,first_frame,last_frame,step_frame).get_append(axis,align);
    }

    //! Load image sequence using FFMPEG's external tool 'ffmpeg'.
    /**
      \param filename Filename, as a C-string.
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_ffmpeg_external(const char *const filename, const char axis='z', const float align=0) {
      return get_load_ffmpeg_external(filename,axis,align).move_to(*this);
    }

    //! Load image sequence using FFMPEG's external tool 'ffmpeg' \newinstance.
    static CImg<T> get_load_ffmpeg_external(const char *const filename, const char axis='z', const float align=0) {
      return CImgList<T>().load_ffmpeg_external(filename).get_append(axis,align);
    }

    //! Load gif file, using Imagemagick or GraphicsMagicks's external tools.
    /**
      \param filename Filename, as a C-string.
      \param axis Concatenation axis, if file contains multiple images. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
    **/
    CImg<T>& load_gif_external(const char *const filename,
                               const char axis='z', const float align=0) {
      return get_load_gif_external(filename,axis,align).move_to(*this);
    }

    //! Load gif file, using ImageMagick or GraphicsMagick's external tool 'convert' \newinstance.
    static CImg<T> get_load_gif_external(const char *const filename,
                                         const char axis='z', const float align=0) {
      return CImgList<T>().load_gif_external(filename).get_append(axis,align);
    }

    //! Load image from a HEIC file.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_heif(const char *const filename) {
      return _load_heif(filename);
    }

    //! Load image from a HEIC file \newinstance.
    static CImg<T> get_load_heif(const char *const filename) {
      return CImg<T>().load_heif(filename);
    }

    CImg<T>& _load_heif(const char *const filename) {
#ifndef cimg_use_heif
      return load_other(filename);
#else
      try {
        heif::Context ctx;
        ctx.read_from_file(filename);

        heif::ImageHandle handle = ctx.get_primary_image_handle();
        const heif::Image image =
          handle.decode_image(heif_colorspace_RGB,handle.has_alpha_channel()?heif_chroma_interleaved_RGBA:
                              heif_chroma_interleaved_RGB);
        const int
          W = image.get_width(heif_channel_interleaved),
          H = image.get_height(heif_channel_interleaved),
          S = handle.has_alpha_channel()?4:3;
        assign(W,H,1,S);

#if LIBHEIF_NUMERIC_VERSION < LIBHEIF_MAKE_VERSION(1, 20, 0) || LIBHEIF_NUMERIC_VERSION > LIBHEIF_MAKE_VERSION(1, 20, 1)
        int stride = 0;
#else
        size_t stride = 0;
#endif
        const unsigned char *const buffer = image.get_plane(heif_channel_interleaved,&stride);
        T *ptr_r = _data, *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2), *ptr_a = S>3?data(0,0,0,3):0;
        cimg_forY(*this,y) {
          const unsigned char *ptrs = buffer + y*stride;
          if (ptr_a) cimg_forX(*this,x) { // RGBA
              *(ptr_r++) = (T)*(ptrs++);
              *(ptr_g++) = (T)*(ptrs++);
              *(ptr_b++) = (T)*(ptrs++);
              *(ptr_a++) = (T)*(ptrs++);
            }
          else cimg_forX(*this,x) { // RGB
              *(ptr_r++) = (T)*(ptrs++);
              *(ptr_g++) = (T)*(ptrs++);
              *(ptr_b++) = (T)*(ptrs++);
            }
        }
      } catch (const heif::Error& e) {
        throw CImgInstanceException(_cimg_instance
                                    "load_heif(): Unable to decode image: %s",
                                    cimg_instance,
                                    e.get_message().c_str());
      } catch (...) {
        throw;
      }
      return *this;
#endif
    }

    //! Load image from a WebP file.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_webp(const char *const filename) {
      return _load_webp(filename);
    }

    //! Load image from a WebP file \newinstance.
    static CImg<T> get_load_webp(const char *const filename) {
      return CImg<T>().load_webp(filename);
    }

    CImg<T>& _load_webp(const char *const filename) {
#ifndef cimg_use_webp
      return load_other(filename);
#else
      std::FILE *file = cimg::fopen(filename, "rb");
      const long data_size = cimg::fsize(file);
      if (data_size <= 0) {
        cimg::fclose(file);
        throw CImgIOException(_cimg_instance
                              "load_webp(): Failed to get file size '%s'.",
                              cimg_instance,
                              filename);
      }
      CImg<ucharT> buffer(data_size);
      cimg::fread(buffer._data, buffer._width, file);
      cimg::fclose(file);

      WebPDecoderConfig config;
      if (!WebPInitDecoderConfig(&config))
        throw CImgIOException(_cimg_instance
                              "load_webp(): Failed to init WebP decoder config.",
                              cimg_instance);

      if (WebPGetFeatures(buffer._data, data_size, &config.input)!=VP8_STATUS_OK)
        throw CImgIOException(_cimg_instance
                              "load_webp(): Failed to get image meta info of '%s'.",
                              cimg_instance,
                              filename);

      if (config.input.has_animation)
        throw CImgIOException(_cimg_instance
                              "load_webp(): Does not support animated WebP '%s'.",
                              cimg_instance,
                              filename);

      int width = config.input.width, height = config.input.height;
      if (config.input.has_alpha) {
        config.output.colorspace = MODE_RGBA;
        assign(width,height,1,4);
      } else {
        config.output.colorspace = MODE_RGB;
        assign(width,height,1,3);
      }
      if (WebPDecode(buffer._data, data_size, &config)!=VP8_STATUS_OK)
        throw CImgIOException(_cimg_instance
                              "load_webp(): Failed to decode image '%s'.",
                              cimg_instance,
                              filename);

      uint8_t *imgData = config.output.u.RGBA.rgba;
      T *ptr_r = _data, *ptr_g = _data + 1UL*width*height,
        *ptr_b = _data + 2UL*width*height;
      T *ptr_a = _spectrum==3 ? NULL : _data + 3UL*width*height;
      cimg_forY(*this,y) {
        const unsigned char *ptrs = (unsigned char*)&imgData[y*width*_spectrum];
        cimg_forX(*this,x) {
          *(ptr_r++) = (T)*(ptrs++);
          *(ptr_g++) = (T)*(ptrs++);
          *(ptr_b++) = (T)*(ptrs++);
          if (ptr_a) *(ptr_a++) = (T)*(ptrs++);
        }
      }
      WebPFreeDecBuffer(&config.output);
      return *this;
#endif
    }

    //! Load image using GraphicsMagick's external tool 'gm'.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_graphicsmagick_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimg_instance
                                    "load_graphicsmagick_external(): Specified filename is (null) or does not exist.",
                                    cimg_instance);
      CImg<charT> command(1024), filename_tmp(256);
      const CImg<charT> s_filename = CImg<charT>::string(filename)._system_strescape();
#if cimg_OS==1
      if (cimg::posix_searchpath("gm")) {
        cimg_snprintf(command,command._width,"%s convert \"%s\" %s:-",
                      cimg::graphicsmagick_path(),
                      s_filename.data(),
#ifdef cimg_use_png
                      "png"
#else
                      "pnm"
#endif
                      );
        std::FILE *file = popen(command,"r");
        if (file) {
          const unsigned int omode = cimg::exception_mode();
          cimg::exception_mode(0);
          try {
#ifdef cimg_use_png
            load_png(file);
#else
            load_pnm(file);
#endif
          } catch (...) {
            pclose(file);
            cimg::exception_mode(omode);
            throw CImgIOException(_cimg_instance
                                  "load_graphicsmagick_external(): Failed to load file '%s' "
                                  "with external command 'gm'.",
                                  cimg_instance,
                                  filename);
          }
          pclose(file);
          return *this;
        }
      }
#endif
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                      cimg::temporary_path(),
                      cimg_directory_separator,
                      cimg::filenamerand(),
#ifdef cimg_use_png
                      "png"
#else
                      "pnm"
#endif
                      );
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"\"%s\" convert \"%s\" \"%s\"",
                    cimg::graphicsmagick_path(),
                    s_filename.data(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data());
      if (cimg::system(command,cimg::graphicsmagick_path())!=0)
        throw CImgIOException(_cimg_instance
                              "load_graphicsmagick_external(): Failed to load file '%s' with external command 'gm'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimg_instance
                              "load_graphicsmagick_external(): Failed to load file '%s' with external command 'gm'.",
                              cimg_instance,
                              filename);

      }
#ifdef cimg_use_png
      load_png(filename_tmp);
#else
      load_pnm(filename_tmp);
#endif
      std::remove(filename_tmp);
      return *this;
    }

    //! Load image using GraphicsMagick's external tool 'gm' \newinstance.
    static CImg<T> get_load_graphicsmagick_external(const char *const filename) {
      return CImg<T>().load_graphicsmagick_external(filename);
    }

    //! Load gzipped image file, using external tool 'gunzip'.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_gzip_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgIOException(_cimg_instance
                              "load_gzip_external(): Specified filename is (null) or does not exist.",
                              cimg_instance);
      CImg<charT> command(1024), filename_tmp(256), body(256);
      const char
        *const ext = cimg::split_filename(filename,body),
        *const ext2 = cimg::split_filename(body,0);

      do {
        if (!cimg::strcasecmp(ext,"gz")) {
          if (*ext2) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                   cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext2);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        } else {
          if (*ext) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                  cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        }
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"\"%s\" -c \"%s\" > \"%s\"",
                    cimg::gunzip_path(),
                    CImg<charT>::string(filename)._system_strescape().data(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data());
      if (cimg::system(command)!=0)
        throw CImgIOException(_cimg_instance
                              "load_gzip_external(): Failed to load file '%s' with external command 'gunzip'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimg_instance
                              "load_gzip_external(): Failed to load file '%s' with external command 'gunzip'.",
                              cimg_instance,
                              filename);

      }
      load(filename_tmp);
      std::remove(filename_tmp);
      return *this;
    }

    //! Load gzipped image file, using external tool 'gunzip' \newinstance.
    static CImg<T> get_load_gzip_external(const char *const filename) {
      return CImg<T>().load_gzip_external(filename);
    }

    //! Load image using ImageMagick's external tool 'convert'.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_imagemagick_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimg_instance
                                    "load_imagemagick_external(): Specified filename is (null) or does not exist.",
                                    cimg_instance);
      CImg<charT> command(1024), filename_tmp(256);
      const CImg<charT> s_filename = CImg<charT>::string(filename)._system_strescape();
      const char *magick_path = cimg::imagemagick_path();
#if cimg_OS==1
      if (cimg::posix_searchpath("magick") || cimg::posix_searchpath("convert")) {
        cimg_snprintf(command,command._width,"%s%s \"%s\" %s:-",
                      magick_path,
                      !cimg::strcasecmp(cimg::split_filename(filename),"pdf")?" -density 400x400":"",
                      s_filename.data(),
#ifdef cimg_use_png
                      "png"
#else
                      "pnm"
#endif
                      );
        std::FILE *file = popen(command,"r");
        if (file) {
          const unsigned int omode = cimg::exception_mode();
          cimg::exception_mode(0);
          try {
#ifdef cimg_use_png
            load_png(file);
#else
            load_pnm(file);
#endif
          } catch (...) {
            pclose(file);
            cimg::exception_mode(omode);
            throw CImgIOException(_cimg_instance
                                  "load_imagemagick_external(): Failed to load file '%s' with "
                                  "external command 'magick/convert'.",
                                  cimg_instance,
                                  filename);
          }
          pclose(file);
          return *this;
        }
      }
#endif
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                      cimg::temporary_path(),
                      cimg_directory_separator,
                      cimg::filenamerand(),
#ifdef cimg_use_png
                      "png"
#else
                      "pnm"
#endif
                      );
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"%s%s \"%s\" \"%s\"",
                    magick_path,
                    !cimg::strcasecmp(cimg::split_filename(filename),"pdf")?" -density 400x400":"",
                    s_filename.data(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data());
      if (cimg::system(command,magick_path)!=0)
        throw CImgIOException(_cimg_instance
                              "load_imagemagick_external(): Failed to load file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimg_instance
                              "load_imagemagick_external(): Failed to load file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);

      }
#ifdef cimg_use_png
      load_png(filename_tmp);
#else
      load_pnm(filename_tmp);
#endif
      std::remove(filename_tmp);
      return *this;
    }

    //! Load image using ImageMagick's external tool 'convert' \newinstance.
    static CImg<T> get_load_imagemagick_external(const char *const filename) {
      return CImg<T>().load_imagemagick_external(filename);
    }

    //! Load image from a DICOM file, using Medcon's external tool 'medcon'.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_medcon_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimg_instance
                                    "load_medcon_external(): Specified filename is (null) or does not exist.",
                                    cimg_instance);
      CImg<charT> command(1024), filename_tmp(256), body(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s.hdr",cimg::filenamerand());
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"\"%s\" -w -c anlz -o \"%s\" -f \"%s\"",
                    cimg::medcon_path(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    CImg<charT>::string(filename)._system_strescape().data());
      cimg::system(command,cimg::medcon_path());
      cimg::split_filename(filename_tmp,body);
      cimg_snprintf(command,command._width,"%s.hdr",body._data);
      if (!cimg::path_exists(command)) {
        cimg_snprintf(command,command._width,"m000-%s.hdr",body._data);
        if (!cimg::path_exists(command)) {
          throw CImgIOException(_cimg_instance
                                "load_medcon_external(): Failed to load file '%s' with external command 'medcon'.",
                                cimg_instance,
                                filename);
        }
      }
      load_analyze(command);
      std::remove(command);
      cimg::split_filename(command,body);
      cimg_snprintf(command,command._width,"%s.img",body._data);
      std::remove(command);
      return *this;
    }

    //! Load image from a DICOM file, using Medcon's external tool 'medcon' \newinstance.
    static CImg<T> get_load_medcon_external(const char *const filename) {
      return CImg<T>().load_medcon_external(filename);
    }

    //! Load image from a .pdf file.
    /**
       \param filename Filename, as a C-string.
       \param resolution Image resolution.
    **/
    CImg<T>& load_pdf_external(const char *const filename, const unsigned int resolution=400) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_pdf_external(): Specified filename is (null).",
                                    cimg_instance);
      CImg<charT> command(1024), filename_tmp(256);
      const CImg<charT> s_filename = CImg<charT>::string(filename)._system_strescape();
#if cimg_OS==1
      std::FILE *file = 0;
      cimg_snprintf(command,command._width,"gs -q -dNOPAUSE -sDEVICE=ppmraw -o - -r%u \"%s\"",
                    resolution,s_filename.data());
      file = popen(command,"r");
      if (file) {
        const unsigned int omode = cimg::exception_mode();
        cimg::exception_mode(0);
        try { load_pnm(file); } catch (...) {
          pclose(file);
          cimg::exception_mode(omode);
          throw CImgIOException(_cimg_instance
                                "load_pdf_external(): Failed to load file '%s' with external command 'gs'.",
                                cimg_instance,
                                filename);
        }
        pclose(file);
        return *this;
      }
#endif
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.ppm",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"gs -q -dNOPAUSE -sDEVICE=ppmraw -o \"%s\" -r%u \"%s\"",
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),resolution,s_filename.data());
      cimg::system(command,"gs");
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimg_instance
                              "load_pdf_external(): Failed to load file '%s' with external command 'gs'.",
                              cimg_instance,
                              filename);
      }
      load_pnm(filename_tmp);
      std::remove(filename_tmp);
      return *this;
    }

    //! Load image from a .pdf file \newinstance.
    static CImg<T> get_load_pdf_external(const char *const filename, const unsigned int resolution=400) {
      return CImg<T>().load_pdf_external(filename,resolution);
    }

    //! Load image from a RAW Color Camera file, using external tool 'dcraw'.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_dcraw_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimg_instance
                                    "load_dcraw_external(): Specified filename is (null) or does not exist.",
                                    cimg_instance);
      CImg<charT> command(1024), filename_tmp(256);
      const CImg<charT> s_filename = CImg<charT>::string(filename)._system_strescape();
#if cimg_OS==1
      cimg_snprintf(command,command._width,"%s -w -4 -c \"%s\"",
                    cimg::dcraw_path(),s_filename.data());
      std::FILE *file = popen(command,"r");
      if (file) {
        const unsigned int omode = cimg::exception_mode();
        cimg::exception_mode(0);
        try { load_pnm(file); } catch (...) {
          pclose(file);
          cimg::exception_mode(omode);
          throw CImgIOException(_cimg_instance
                                "load_dcraw_external(): Failed to load file '%s' with external command 'dcraw'.",
                                cimg_instance,
                                filename);
        }
        pclose(file);
        return *this;
      }
#endif
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.ppm",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"\"%s\" -w -4 -c \"%s\" > \"%s\"",
                    cimg::dcraw_path(),s_filename.data(),CImg<charT>::string(filename_tmp)._system_strescape().data());
      cimg::system(command,cimg::dcraw_path());
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimg_instance
                              "load_dcraw_external(): Failed to load file '%s' with external command 'dcraw'.",
                              cimg_instance,
                              filename);

      }
      load_pnm(filename_tmp);
      std::remove(filename_tmp);
      return *this;
    }

    //! Load image from a RAW Color Camera file, using external tool 'dcraw' \newinstance.
    static CImg<T> get_load_dcraw_external(const char *const filename) {
      return CImg<T>().load_dcraw_external(filename);
    }

#ifdef cimg_use_opencv

    // Convert a continuous cv::Mat<uchar> to a CImg<uchar>.
    static CImg<ucharT> _cvmat2cimg(const cv::Mat &src) {
      if (src.channels()==1) return CImg<ucharT>(src.ptr(),src.cols,src.rows,1,1);
      else if (src.channels()==3) { // BGR
        CImg<ucharT> res(src.cols,src.rows,1,src.channels());
        const unsigned char *ptrs = src.ptr();
        unsigned char *pR = res.data(), *pG = res.data(0,0,0,1), *pB = res.data(0,0,0,2);
        cimg_forXY(res,x,y) { *(pB++) = *(ptrs++); *(pG++) = *(ptrs++); *(pR++) = *(ptrs++); }
        return res;
      }
      return CImg<ucharT>(src.ptr(),src.channels(),src.cols,src.rows,1,true).get_permute_axes("yzcx");
    }

    // Convert a CImg<T> to a cv::Mat.
    cv::Mat _cimg2cvmat() const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "_cimg2cvmat() : Instance image is empty.",
                                    cimg_instance);
      if (_spectrum==2)
        throw CImgInstanceException(_cimg_instance
                                    "_cimg2cvmat() : Invalid number of channels (should be '1' or '3+').",
                                    cimg_instance);
      if (_depth!=1)
        throw CImgInstanceException(_cimg_instance
                                    "_cimg2cvmat() : Invalid number of slices (should be '1').",
                                    cimg_instance);
      int mat_type = -1;
      if (pixel_type()==cimg::type<unsigned char>::string()) mat_type = CV_8UC1;
      if (pixel_type()==cimg::type<char>::string()) mat_type = CV_8SC1;
      if (pixel_type()==cimg::type<unsigned short>::string()) mat_type = CV_16UC1;
      if (pixel_type()==cimg::type<short>::string()) mat_type = CV_16SC1;
      if (pixel_type()==cimg::type<int>::string()) mat_type = CV_32SC1;
      if (pixel_type()==cimg::type<float>::string()) mat_type = CV_32FC1;
      if (pixel_type()==cimg::type<double>::string()) mat_type = CV_64FC1;
      if (mat_type<0)
        throw CImgInstanceException(_cimg_instance
                                    "_cvmat2cimg() : pixel type '%s' is not supported.",
                                    cimg_instance,pixel_type());
      cv::Mat res;
      if (_spectrum>1) {
        cv::Mat *const channels = new cv::Mat[_spectrum];
        cimg_forC(*this,c)
          channels[c] = cv::Mat(_height,_width,mat_type,_data + _width*_height*(_spectrum - 1 - c));
        cv::merge(channels,_spectrum,res);
        delete[] channels;
      } else res = cv::Mat(_height,_width,mat_type,_data).clone();

      return res;
    }

#endif

    //! Captures an image from a connected camera device (requires OpenCV).
    /**
       This function allows you to directly acquire an image from a camera device (e.g., webcam)
       connected to the system. The captured image is stored in the current CImg<T> instance.

       \param camera_index Index of the camera to capture images from (from 0 to 63).
       \param capture_width Width of the desired image ('0' stands for default value).
       \param capture_height Height of the desired image ('0' stands for default value).
       \param skip_frames Number of frames to skip before the capture.
       \param release_camera Indicates whether the camera resource must be released at the end of the function.
       \return Reference to the current image instance, now containing the captured camera frame.

       \code
       // Example usage:
       CImg<unsigned char> img;
       img.load_camera(); // Capture an image from the default camera
       img.display();
       \endcode

       \note Requires your code to be linked with the OpenCV library (macro \c cimg_use_opencv enabled).
       \warning Throws a CImgIOException if no camera is found or if the capture fails.
    */
    CImg<T>& load_camera(const unsigned int camera_index=0,
                         const unsigned int capture_width=0, const unsigned int capture_height=0,
                         const unsigned int skip_frames=0, const bool release_camera=true) {
#ifdef cimg_use_opencv
      if (camera_index>=64)
        throw CImgArgumentException(_cimg_instance
                                    "load_camera(): Invalid request for camera #%u "
                                    "(no more than 100 cameras can be managed simultaneously).",
                                    cimg_instance,
                                    camera_index);
      static cv::VideoCapture *captures[64] = {};
      static unsigned int captures_w[64], captures_h[64];
      if (release_camera) {
        cimg::mutex(9);
        if (captures[camera_index]) captures[camera_index]->release();
        delete captures[camera_index];
        captures[camera_index] = 0;
        captures_w[camera_index] = captures_h[camera_index] = 0;
        cimg::mutex(9,0);
        return *this;
      }
      if (!captures[camera_index]) {
        cimg::mutex(9);
        captures[camera_index] = new cv::VideoCapture(camera_index);
        captures_w[camera_index] = captures_h[camera_index] = 0;
        if (!captures[camera_index]->isOpened()) {
          delete captures[camera_index];
          captures[camera_index] = 0;
          cimg::mutex(9,0);
          throw CImgIOException(_cimg_instance
                                "load_camera(): Failed to initialize camera #%u.",
                                cimg_instance,
                                camera_index);
        }
        cimg::mutex(9,0);
      }
      cimg::mutex(9);
      if (capture_width!=captures_w[camera_index]) {
        captures[camera_index]->set(_cimg_cap_prop_frame_width,capture_width);
        captures_w[camera_index] = capture_width;
      }
      if (capture_height!=captures_h[camera_index]) {
        captures[camera_index]->set(_cimg_cap_prop_frame_height,capture_height);
        captures_h[camera_index] = capture_height;
      }
      for (unsigned int i = 0; i<skip_frames; ++i) captures[camera_index]->grab();
      cv::Mat cvimg;
      captures[camera_index]->read(cvimg);
      if (cvimg.empty()) {
        cimg::mutex(9,0);
        load_camera(camera_index,0,0,0,true); // Release camera
        throw CImgIOException(_cimg_instance
                              "load_camera(): Failed to retrieve a %ux%u frame from camera #%u.",
                              cimg_instance,
                              capture_width,capture_height,camera_index);
      } else _cvmat2cimg(cvimg).move_to(*this);
      cimg::mutex(9,0);
      return *this;
#else
      cimg::unused(camera_index,skip_frames,release_camera,capture_width,capture_height);
      throw CImgIOException(_cimg_instance
                            "load_camera(): This function requires features from the OpenCV library "
                            "('-Dcimg_use_opencv' must be defined).",
                            cimg_instance);
#endif
    }

    //! Load image from a camera stream, using OpenCV \newinstance.
    static CImg<T> get_load_camera(const unsigned int camera_index=0,
                                   const unsigned int capture_width=0, const unsigned int capture_height=0,
                                   const unsigned int skip_frames=0, const bool release_camera=true) {
      return CImg<T>().load_camera(camera_index,capture_width,capture_height,skip_frames,release_camera);
    }

    //! Load image using various non-native ways.
    /**
       \param filename Filename, as a C-string.
    **/
    CImg<T>& load_other(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "load_other(): Specified filename is (null).",
                                    cimg_instance);

      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      try { load_magick(filename); }
      catch (CImgException&) {
        try { load_imagemagick_external(filename); }
        catch (CImgException&) {
          try { load_graphicsmagick_external(filename); }
          catch (CImgException&) {
            try { load_cimg(filename); }
            catch (CImgException&) {
              try {
                cimg::fclose(cimg::fopen(filename,"rb"));
              } catch (CImgException&) {
                cimg::exception_mode(omode);
                throw CImgIOException(_cimg_instance
                                      "load_other(): Failed to open file '%s'.",
                                      cimg_instance,
                                      filename);
              }
              cimg::exception_mode(omode);
              throw CImgIOException(_cimg_instance
                                    "load_other(): Failed to recognize format of file '%s'.",
                                    cimg_instance,
                                    filename);
            }
          }
        }
      }
      cimg::exception_mode(omode);
      return *this;
    }

    //! Load image using various non-native ways \newinstance.
    static CImg<T> get_load_other(const char *const filename) {
      return CImg<T>().load_other(filename);
    }

    //@}
    //---------------------------
    //
    //! \name Data Output
    //@{
    //---------------------------

    //! Display information about the image data.
    /**
       \param title Name for the considered image.
       \param display_stats Specifies whether to compute and display image statistics.
    **/
    const CImg<T>& print(const char *const title=0, const bool display_stats=true) const {

      int xm = 0, ym = 0, zm = 0, vm = 0, xM = 0, yM = 0, zM = 0, vM = 0;
      CImg<doubleT> st;
      if (!is_empty() && display_stats) {
        st = get_stats();
        xm = (int)st[4]; ym = (int)st[5], zm = (int)st[6], vm = (int)st[7];
        xM = (int)st[8]; yM = (int)st[9], zM = (int)st[10], vM = (int)st[11];
      }

      const ulongT siz = size(), msiz = siz*sizeof(T), siz1 = siz - 1,
        mdisp = msiz<8*1024?0U:msiz<8*1024*1024?1U:2U, width1 = _width - 1;

      CImg<charT> _title(64);
      if (!title) cimg_snprintf(_title,_title._width,"CImg<%s>",pixel_type());

      std::fprintf(cimg::output(),"%s%s%s%s: %sthis%s = %p, %ssize%s = (%u,%u,%u,%u) [%lu %s], %sdata%s = (%s*)%p",
                   cimg::t_magenta(),cimg::t_bold(),title?title:_title._data,cimg::t_normal(),
                   cimg::t_bold(),cimg::t_normal(),(void*)this,
                   cimg::t_bold(),cimg::t_normal(),_width,_height,_depth,_spectrum,
                   (unsigned long)(mdisp==0?msiz:(mdisp==1?(msiz>>10):(msiz>>20))),
                   mdisp==0?"b":(mdisp==1?"Kio":"Mio"),
                   cimg::t_bold(),cimg::t_normal(),pixel_type(),(void*)begin());
      if (_data)
        std::fprintf(cimg::output(),"..%p (%s) = [ ",(void*)((char*)end() - 1),_is_shared?"shared":"non-shared");
      else std::fprintf(cimg::output()," (%s) = [ ",_is_shared?"shared":"non-shared");

      if (!is_empty()) cimg_foroff(*this,off) {
        std::fprintf(cimg::output(),cimg::type<T>::format_s(),cimg::type<T>::format(_data[off]));
        if (off!=siz1) std::fprintf(cimg::output(),"%s",off%_width==width1?" ; ":" ");
        if (off==7 && siz>16) { off = siz1 - 8; std::fprintf(cimg::output(),"... "); }
      }
      if (!is_empty() && display_stats)
        std::fprintf(cimg::output(),
                     " ], %smin%s = %g, %smax%s = %g, %smean%s = %g, %sstd%s = %g, %snorm%s = %g, "
                     "%scoords_min%s = (%u,%u,%u,%u), %scoords_max%s = (%u,%u,%u,%u).\n",
                     cimg::t_bold(),cimg::t_normal(),st[0],
                     cimg::t_bold(),cimg::t_normal(),st[1],
                     cimg::t_bold(),cimg::t_normal(),st[2],
                     cimg::t_bold(),cimg::t_normal(),std::sqrt(st[3]),
                     cimg::t_bold(),cimg::t_normal(),st[14],
                     cimg::t_bold(),cimg::t_normal(),xm,ym,zm,vm,
                     cimg::t_bold(),cimg::t_normal(),xM,yM,zM,vM);
      else std::fprintf(cimg::output(),"%s].\n",is_empty()?"":" ");
      std::fflush(cimg::output());
      return *this;
    }

    //! Display image into a CImgDisplay window.
    /**
       \param disp Display window.
    **/
    const CImg<T>& display(CImgDisplay& disp) const {
      disp.display(*this);
      return *this;
    }

    //! Display image into a CImgDisplay window, in an interactive way.
    /**
        \param disp Display window.
        \param display_info Indicates whether image information is displayed on the standard output.
        \param[in,out] XYZ Contains the XYZ coordinates at start / exit of the function.
        \param exit_on_anykey Exit function when any key is pressed.
    **/
    const CImg<T>& display(CImgDisplay &disp, const bool display_info, unsigned int *const XYZ=0,
                           const bool exit_on_anykey=false) const {
      return _display(disp,0,display_info,XYZ,exit_on_anykey,false);
    }

    //! Display image into an interactive window.
    /**
        \param title Window title
        \param display_info Indicates whether image information is displayed on the standard output.
        \param[in,out] XYZ Contains the XYZ coordinates at start / exit of the function.
        \param exit_on_anykey Exit function when any key is pressed.
    **/
    const CImg<T>& display(const char *const title=0, const bool display_info=true, unsigned int *const XYZ=0,
                           const bool exit_on_anykey=false) const {
      CImgDisplay disp;
      return _display(disp,title,display_info,XYZ,exit_on_anykey,false);
    }

    const CImg<T>& _display(CImgDisplay &disp, const char *const title, const bool display_info,
                            unsigned int *const XYZ, const bool exit_on_anykey,
                            const bool exit_on_singleclick) const {
      unsigned int oldw = 0, oldh = 0, _XYZ[3] = {}, key = 0;
      int x0 = 0, y0 = 0, z0 = 0, x1 = width() - 1, y1 = height() - 1, z1 = depth() - 1,
        old_mouse_x = -1, old_mouse_y = -1;

      if (!disp) {
        disp.assign(cimg_fitscreen(_width,_height,_depth),title?title:0,1);
        if (!title) disp.set_title("CImg<%s> (%ux%ux%ux%u)",pixel_type(),_width,_height,_depth,_spectrum);
        else disp.set_title("%s",title);
      } else if (title) disp.set_title("%s",title);

      disp.show().flush();
      const CImg<char> dtitle = CImg<char>::string(disp.title());
      if (display_info) print(dtitle);

      CImg<T> zoom;
      for (bool reset_view = true, resize_disp = false, is_first_select = true; !key && !disp.is_closed(); ) {
        if (reset_view) {
          if (XYZ) { _XYZ[0] = XYZ[0]; _XYZ[1] = XYZ[1]; _XYZ[2] = XYZ[2]; }
          else {
            _XYZ[0] = (unsigned int)(x0 + x1 + 1)/2;
            _XYZ[1] = (unsigned int)(y0 + y1 + 1)/2;
            _XYZ[2] = (unsigned int)(z0 + z1 + 1)/2;
          }
          x0 = 0; y0 = 0; z0 = 0; x1 = width() - 1; y1 = height() - 1; z1 = depth() - 1;
          disp.resize(cimg_fitscreen(_width,_height,_depth),false);
          oldw = disp._width; oldh = disp._height;
          resize_disp = true;
          reset_view = false;
        }
        if (!x0 && !y0 && !z0 && x1==width() - 1 && y1==height() - 1 && z1==depth() - 1) {
          if (is_empty()) zoom.assign(1,1,1,1,(T)0); else zoom.assign();
        } else zoom = get_crop(x0,y0,z0,x1,y1,z1);

        const CImg<T>& visu = zoom?zoom:*this;
        const unsigned int
          dx = 1U + x1 - x0, dy = 1U + y1 - y0, dz = 1U + z1 - z0,
          tw = dx + (dz>1?dz:0U), th = dy + (dz>1?dz:0U);
        if (!is_empty() && !disp.is_fullscreen() && resize_disp) {
          const float
            ttw = (float)tw*disp.width()/oldw, tth = (float)th*disp.height()/oldh,
            dM = std::max(ttw,tth), diM = (float)std::max(disp.width(),disp.height());
          const unsigned int
            imgw = (unsigned int)(ttw*diM/dM), imgh = (unsigned int)(tth*diM/dM);
          disp.set_fullscreen(false).resize(cimg_fitscreen(imgw,imgh,1),false);
          resize_disp = false;
        }
        oldw = tw; oldh = th;

        bool
          go_up = false, go_down = false, go_left = false, go_right = false,
          go_inc = false, go_dec = false, go_in = false, go_out = false,
          go_in_center = false;

        disp.set_title("%s",dtitle._data);
        if (_width>1 && visu._width==1) disp.set_title("%s | x=%u",disp._title,x0);
        if (_height>1 && visu._height==1) disp.set_title("%s | y=%u",disp._title,y0);
        if (_depth>1 && visu._depth==1) disp.set_title("%s | z=%u",disp._title,z0);

        disp._mouse_x = old_mouse_x; disp._mouse_y = old_mouse_y;
        CImg<intT> selection = visu._select(disp,0,2,_XYZ,x0,y0,z0,true,is_first_select,_depth>1,true);
        old_mouse_x = disp._mouse_x; old_mouse_y = disp._mouse_y;
        is_first_select = false;

        if (disp.wheel()) {
          if ((disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) &&
              (disp.is_keySHIFTLEFT() || disp.is_keySHIFTRIGHT())) {
            go_left = !(go_right = disp.wheel()>0);
          } else if (disp.is_keySHIFTLEFT() || disp.is_keySHIFTRIGHT()) {
            go_down = !(go_up = disp.wheel()>0);
          } else if (depth()==1 || disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            go_out = !(go_in = disp.wheel()>0); go_in_center = false;
          }
          disp.set_wheel();
        }

        const int
          sx0 = selection(0), sy0 = selection(1), sz0 = selection(2),
          sx1 = selection(3), sy1 = selection(4), sz1 = selection(5);
        if (sx0>=0 && sy0>=0 && sz0>=0 && sx1>=0 && sy1>=0 && sz1>=0) {
          x1 = x0 + sx1; y1 = y0 + sy1; z1 = z0 + sz1;
          x0+=sx0; y0+=sy0; z0+=sz0;
          if ((sx0==sx1 && sy0==sy1) || (_depth>1 && sx0==sx1 && sz0==sz1) || (_depth>1 && sy0==sy1 && sz0==sz1)) {
            if (exit_on_singleclick && (!zoom || is_empty())) break; else reset_view = true;
          }
          resize_disp = true;
        } else switch (key = disp.key()) {
#if cimg_OS!=2
          case cimg::keyCTRLRIGHT : case cimg::keySHIFTRIGHT :
#endif
          case 0 : case cimg::keyCTRLLEFT : case cimg::keySHIFTLEFT : key = 0; break;
          case cimg::keyP : if (visu._depth>1 && (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT())) {
              // Special mode: play stack of frames.
              const unsigned int
                w1 = visu._width*disp.width()/(visu._width + (visu._depth>1?visu._depth:0)),
                h1 = visu._height*disp.height()/(visu._height + (visu._depth>1?visu._depth:0));
              float frame_timing = 5;
              bool is_stopped = false;
              disp.set_key(key,false).set_wheel().resize(cimg_fitscreen(w1,h1,1),false); key = 0;
              for (unsigned int timer = 0; !key && !disp.is_closed() && !disp.button(); ) {
                if (disp.is_resized()) disp.resize(false);
                if (!timer) {
                  visu.get_slice((int)_XYZ[2]).display(disp.set_title("%s | z=%d",dtitle.data(),_XYZ[2]));
                  (++_XYZ[2])%=visu._depth;
                }
                if (!is_stopped) { if (++timer>(unsigned int)frame_timing) timer = 0; } else timer = ~0U;
                if (disp.wheel()) { frame_timing-=disp.wheel()/3.f; disp.set_wheel(); }
                switch (key = disp.key()) {
#if cimg_OS!=2
                case cimg::keyCTRLRIGHT :
#endif
                case cimg::keyCTRLLEFT : key = 0; break;
                case cimg::keyPAGEUP : frame_timing-=0.3f; key = 0; break;
                case cimg::keyPAGEDOWN : frame_timing+=0.3f; key = 0; break;
                case cimg::keySPACE : is_stopped = !is_stopped; disp.set_key(key,false); key = 0; break;
                case cimg::keyARROWLEFT : case cimg::keyARROWUP : is_stopped = true; timer = 0; key = 0; break;
                case cimg::keyARROWRIGHT : case cimg::keyARROWDOWN : is_stopped = true;
                  (_XYZ[2]+=visu._depth - 2)%=visu._depth; timer = 0; key = 0; break;
                case cimg::keyD : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
                    disp.set_fullscreen(false).
                      resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                             CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false);
                    disp.set_key(key,false); key = 0;
                  } break;
                case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
                    disp.set_fullscreen(false).
                      resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false).set_key(key,false); key = 0;
                  } break;
                case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
                    disp.set_fullscreen(false).
                      resize(cimg_fitscreen(_width,_height,_depth),false).set_key(key,false); key = 0;
                  } break;
                case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
                    disp.resize(disp.screen_width(),disp.screen_height(),false).
                      toggle_fullscreen().set_key(key,false); key = 0;
                  } break;
                }
                frame_timing = frame_timing<1?1:(frame_timing>39?39:frame_timing);
                disp.wait(20);
              }
              const unsigned int
                w2 = (visu._width + (visu._depth>1?visu._depth:0))*disp.width()/visu._width,
                h2 = (visu._height + (visu._depth>1?visu._depth:0))*disp.height()/visu._height;
              disp.resize(cimg_fitscreen(w2,h2,1),false).set_title(dtitle.data()).set_key().set_button().set_wheel();
              key = 0;
            } break;
          case cimg::keyHOME : reset_view = resize_disp = true; key = 0; break;
          case cimg::keyPADADD : go_in = true; go_in_center = true; key = 0; break;
          case cimg::keyPADSUB : go_out = true; key = 0; break;
          case cimg::keyARROWLEFT : case cimg::keyPAD4: go_left = true; key = 0; break;
          case cimg::keyARROWRIGHT : case cimg::keyPAD6: go_right = true; key = 0; break;
          case cimg::keyARROWUP : case cimg::keyPAD8: go_up = true; key = 0; break;
          case cimg::keyARROWDOWN : case cimg::keyPAD2: go_down = true; key = 0; break;
          case cimg::keyPAD7 : go_up = go_left = true; key = 0; break;
          case cimg::keyPAD9 : go_up = go_right = true; key = 0; break;
          case cimg::keyPAD1 : go_down = go_left = true; key = 0; break;
          case cimg::keyPAD3 : go_down = go_right = true; key = 0; break;
          case cimg::keyPAGEUP : go_inc = true; key = 0; break;
          case cimg::keyPAGEDOWN : go_dec = true; key = 0; break;
          }
        if (go_in) {
          const int
            mx = go_in_center?disp.width()/2:disp.mouse_x(),
            my = go_in_center?disp.height()/2:disp.mouse_y(),
            mX = mx*(width() + (depth()>1?depth():0))/disp.width(),
            mY = my*(height() + (depth()>1?depth():0))/disp.height();
          int X = (int)_XYZ[0], Y = (int)_XYZ[1], Z = (int)_XYZ[2];
          if (mX<width() && mY<height())  {
            X = x0 + mX*(1 + x1 - x0)/width(); Y = y0 + mY*(1 + y1 - y0)/height();
          }
          if (mX<width() && mY>=height()) {
            X = x0 + mX*(1 + x1 - x0)/width(); Z = z0 + (mY - height())*(1 + z1 - z0)/depth();
          }
          if (mX>=width() && mY<height()) {
            Y = y0 + mY*(1 + y1 - y0)/height(); Z = z0 + (mX - width())*(1 + z1 - z0)/depth();
          }
          if (x1 - x0>4) { x0 = X - 3*(X - x0)/4; x1 = X + 3*(x1 - X)/4; }
          if (y1 - y0>4) { y0 = Y - 3*(Y - y0)/4; y1 = Y + 3*(y1 - Y)/4; }
          if (z1 - z0>4) { z0 = Z - 3*(Z - z0)/4; z1 = Z + 3*(z1 - Z)/4; }
        }
        if (go_out) {
          const int
            delta_x = (x1 - x0)/8, delta_y = (y1 - y0)/8, delta_z = (z1 - z0)/8,
            ndelta_x = delta_x?delta_x:(_width>1),
            ndelta_y = delta_y?delta_y:(_height>1),
            ndelta_z = delta_z?delta_z:(_depth>1);
          x0-=ndelta_x; y0-=ndelta_y; z0-=ndelta_z;
          x1+=ndelta_x; y1+=ndelta_y; z1+=ndelta_z;
          if (x0<0) { x1-=x0; x0 = 0; if (x1>=width()) x1 = width() - 1; }
          if (y0<0) { y1-=y0; y0 = 0; if (y1>=height()) y1 = height() - 1; }
          if (z0<0) { z1-=z0; z0 = 0; if (z1>=depth()) z1 = depth() - 1; }
          if (x1>=width()) { x0-=(x1 - width() + 1); x1 = width() - 1; if (x0<0) x0 = 0; }
          if (y1>=height()) { y0-=(y1 - height() + 1); y1 = height() - 1; if (y0<0) y0 = 0; }
          if (z1>=depth()) { z0-=(z1 - depth() + 1); z1 = depth() - 1; if (z0<0) z0 = 0; }
          const float
            ratio = (float)(x1-x0)/(y1-y0),
            ratiow = (float)disp._width/disp._height,
            sub = std::min(cimg::abs(ratio - ratiow),cimg::abs(1/ratio-1/ratiow));
          if (sub>0.01) resize_disp = true;
        }
        if (go_left) {
          const int delta = (x1 - x0)/4, ndelta = delta?delta:(_width>1);
          if (x0 - ndelta>=0) { x0-=ndelta; x1-=ndelta; }
          else { x1-=x0; x0 = 0; }
        }
        if (go_right) {
          const int delta = (x1 - x0)/4, ndelta = delta?delta:(_width>1);
          if (x1+ndelta<width()) { x0+=ndelta; x1+=ndelta; }
          else { x0+=(width() - 1 - x1); x1 = width() - 1; }
        }
        if (go_up) {
          const int delta = (y1 - y0)/4, ndelta = delta?delta:(_height>1);
          if (y0 - ndelta>=0) { y0-=ndelta; y1-=ndelta; }
          else { y1-=y0; y0 = 0; }
        }
        if (go_down) {
          const int delta = (y1 - y0)/4, ndelta = delta?delta:(_height>1);
          if (y1+ndelta<height()) { y0+=ndelta; y1+=ndelta; }
          else { y0+=(height() - 1 - y1); y1 = height() - 1; }
        }
        if (go_inc) {
          const int delta = (z1 - z0)/4, ndelta = delta?delta:(_depth>1);
          if (z0 - ndelta>=0) { z0-=ndelta; z1-=ndelta; }
          else { z1-=z0; z0 = 0; }
        }
        if (go_dec) {
          const int delta = (z1 - z0)/4, ndelta = delta?delta:(_depth>1);
          if (z1+ndelta<depth()) { z0+=ndelta; z1+=ndelta; }
          else { z0+=(depth() - 1 - z1); z1 = depth() - 1; }
        }
        disp.wait(100);
        if (!exit_on_anykey && key && key!=cimg::keyESC &&
            (key!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          key = 0;
        }
      }
      disp.set_key(key);
      if (XYZ) { XYZ[0] = _XYZ[0]; XYZ[1] = _XYZ[1]; XYZ[2] = _XYZ[2]; }
      return *this;
    }

    //! Display a 3D object in an interactive window.
    /**
       \param disp Display window.
       \param vertices Vertices data of the 3D object.
       \param primitives Primitives data of the 3D object.
       \param colors Colors data of the 3D object.
       \param opacities Opacities data of the 3D object.
       \param centering Indicates whether the 3D object should be centered for display.
       \param render_static Rendering mode.
       \param render_motion Rendering mode when the 3D object is in motion.
       \param is_double_sided Indicates whether the object primitives are double-sided.
       \param focal Focal length (0 for parallel projection).
       \param light_x X-coordinate of the light source.
       \param light_y Y-coordinate of the light source.
       \param light_z Z-coordinate of the light source.
       \param specular_lightness Amount of specular light.
       \param specular_shininess Shininess of the object material.
       \param display_axes Indicates whether the 3D axes are displayed.
       \param pose_matrix Pointer to 12 values defining a 3D pose (as a 4x3 matrix).
       \param exit_on_anykey Exit function when any key is pressed.
    **/
    template<typename tp, typename tf, typename tc, typename to>
    const CImg<T>& display_object3d(CImgDisplay& disp,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const CImgList<tc>& colors,
                                    const to& opacities,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return _display_object3d(disp,0,vertices,primitives,colors,opacities,centering,render_static,
                               render_motion,is_double_sided,focal,
                               light_x,light_y,light_z,specular_lightness,specular_shininess,
                               display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp, typename tf, typename tc, typename to>
    const CImg<T>& display_object3d(const char *const title,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const CImgList<tc>& colors,
                                    const to& opacities,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      CImgDisplay disp;
      return _display_object3d(disp,title,vertices,primitives,colors,opacities,centering,render_static,
                               render_motion,is_double_sided,focal,
                               light_x,light_y,light_z,specular_lightness,specular_shininess,
                               display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp, typename tf, typename tc>
    const CImg<T>& display_object3d(CImgDisplay &disp,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const CImgList<tc>& colors,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(disp,vertices,primitives,colors,CImgList<floatT>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp, typename tf, typename tc>
    const CImg<T>& display_object3d(const char *const title,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const CImgList<tc>& colors,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(title,vertices,primitives,colors,CImgList<floatT>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp, typename tf>
    const CImg<T>& display_object3d(CImgDisplay &disp,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(disp,vertices,primitives,CImgList<T>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }


    //! Display a 3D object in an interactive window \overload.
    template<typename tp, typename tf>
    const CImg<T>& display_object3d(const char *const title,
                                    const CImg<tp>& vertices,
                                    const CImgList<tf>& primitives,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(title,vertices,primitives,CImgList<T>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp>
    const CImg<T>& display_object3d(CImgDisplay &disp,
                                    const CImg<tp>& vertices,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(disp,vertices,CImgList<uintT>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }

    //! Display a 3D object in an interactive window \overload.
    template<typename tp>
    const CImg<T>& display_object3d(const char *const title,
                                    const CImg<tp>& vertices,
                                    const bool centering=true,
                                    const int render_static=4, const int render_motion=1,
                                    const bool is_double_sided=false, const float focal=700,
                                    const float light_x=0, const float light_y=0, const float light_z=-5e8f,
                                    const float specular_lightness=0.25f, const float specular_shininess=0.1f,
                                    const bool display_axes=true, float *const pose_matrix=0,
                                    const bool exit_on_anykey=false) const {
      return display_object3d(title,vertices,CImgList<uintT>(),centering,
                              render_static,render_motion,is_double_sided,focal,
                              light_x,light_y,light_z,specular_lightness,specular_shininess,
                              display_axes,pose_matrix,exit_on_anykey);
    }

    template<typename tp, typename tf, typename tc, typename to>
    const CImg<T>& _display_object3d(CImgDisplay& disp, const char *const title,
                                     const CImg<tp>& vertices,
                                     const CImgList<tf>& primitives,
                                     const CImgList<tc>& colors,
                                     const to& opacities,
                                     const bool centering,
                                     const int render_static, const int render_motion,
                                     const bool is_double_sided, const float focal,
                                     const float light_x, const float light_y, const float light_z,
                                     const float specular_lightness, const float specular_shininess,
                                     const bool display_axes, float *const pose_matrix,
                                     const bool exit_on_anykey) const {
      // Check input arguments.
      if (is_empty()) {
        CImg<T> background;
        if (colors && colors[0].size()==1) background.assign(1,2,1,1,64,128);
        else background.assign(1,2,1,3,32,64,32,116,64,96);
        if (disp) background.resize(disp.width(),disp.height(),1,-100,3);
        else background.resize(cimg_fitscreen(CImgDisplay::screen_width()/2,
                                              CImgDisplay::screen_height()/2,1),1,-100,3);
        background._display_object3d(disp,title,vertices,primitives,colors,opacities,centering,
                                     render_static,render_motion,is_double_sided,focal,
                                     light_x,light_y,light_z,specular_lightness,specular_shininess,
                                     display_axes,pose_matrix,exit_on_anykey);
        return *this;
      } else { if (disp) disp.resize(*this,false); }
      CImg<charT> error_message(1024);
      if (!vertices.is_object3d(primitives,colors,opacities,true,error_message))
        throw CImgArgumentException(_cimg_instance
                                    "display_object3d(): Invalid specified 3D object (%u,%u) (%s).",
                                    cimg_instance,vertices._width,primitives._width,error_message.data());
      if (vertices._width && !primitives) {
        CImgList<tf> nprimitives(vertices._width,1,1,1,1);
        cimglist_for(nprimitives,l) nprimitives(l,0) = (tf)l;
        return _display_object3d(disp,title,vertices,nprimitives,colors,opacities,centering,
                                 render_static,render_motion,is_double_sided,focal,
                                 light_x,light_y,light_z,specular_lightness,specular_shininess,
                                 display_axes,pose_matrix,exit_on_anykey);
      }
      if (!disp) {
        disp.assign(cimg_fitscreen(_width,_height,_depth),title?title:0,3);
        if (!title) disp.set_title("CImg<%s> (%u vertices, %u primitives)",
                                   pixel_type(),vertices._width,primitives._width);
      } else if (title) disp.set_title("%s",title);

      // Init 3D objects and compute object statistics.
      CImg<floatT>
        pose,
        rotated_vertices(vertices._width,3),
        bbox_vertices, rotated_bbox_vertices,
        axes_vertices, rotated_axes_vertices,
        bbox_opacities, axes_opacities;
      CImgList<uintT> bbox_primitives, axes_primitives;
      CImgList<tf> reverse_primitives;
      CImgList<T> bbox_colors, bbox_colors2, axes_colors;
      unsigned int ns_width = 0, ns_height = 0;
      int _is_double_sided = (int)is_double_sided;
      bool ndisplay_axes = display_axes;
      const CImg<T>
        background_color(1,1,1,_spectrum,0),
        foreground_color(1,1,1,_spectrum,(T)std::min((int)cimg::type<T>::max(),255));
      float
        Xoff = 0, Yoff = 0, Zoff = 0, sprite_scale = 1,
        xm = 0, xM = vertices?vertices.get_shared_row(0).max_min(xm):0,
        ym = 0, yM = vertices?vertices.get_shared_row(1).max_min(ym):0,
        zm = 0, zM = vertices?vertices.get_shared_row(2).max_min(zm):0;
      const float delta = cimg::max(xM - xm,yM - ym,zM - zm);

      rotated_bbox_vertices = bbox_vertices.assign(8,3,1,1,
                                                   xm,xM,xM,xm,xm,xM,xM,xm,
                                                   ym,ym,yM,yM,ym,ym,yM,yM,
                                                   zm,zm,zm,zm,zM,zM,zM,zM);
      CImg<uintT>(1,6*4,1,1, 0,3,2,1, 4,5,6,7, 1,2,6,5, 0,4,7,3, 0,1,5,4, 2,3,7,6).
        get_split('y',6).move_to(bbox_primitives);
      bbox_colors.assign(6,_spectrum,1,1,1,background_color[0]);
      bbox_colors2.assign(6,_spectrum,1,1,1,foreground_color[0]);
      bbox_opacities.assign(bbox_colors._width,1,1,1,0.3f);

      rotated_axes_vertices = axes_vertices.assign(7,3,1,1,
                                                   0,20,0,0,22,-6,-6,
                                                   0,0,20,0,-6,22,-6,
                                                   0,0,0,20,0,0,22);
      axes_opacities.assign(3,1,1,1,1);
      axes_colors.assign(3,_spectrum,1,1,1,foreground_color[0]);
      CImg<uintT>(1,3*2,1,1, 0,1, 0,2, 0,3).get_split('y',3).move_to(axes_primitives);

      // Begin user interaction loop.
      CImg<T> visu0(*this,false), visu;
      CImg<floatT> zbuffer(visu0.width(),visu0.height(),1,1,0);
      bool init_pose = true, clicked = false, redraw = true;
      unsigned int key = 0, font_size = 32;
      int
        x0 = 0, y0 = 0, x1 = 0, y1 = 0,
        nrender_static = render_static,
        nrender_motion = render_motion;
      disp.show().flush();

      while (!disp.is_closed() && !key) {

        // Init object pose.
        if (init_pose) {
          const float
            ratio = delta>0?(2.f*std::min(disp.width(),disp.height())/(3.f*delta)):1,
            dx = (xM + xm)/2, dy = (yM + ym)/2, dz = (zM + zm)/2;
          if (centering)
            CImg<floatT>(4,3,1,1, ratio,0.,0.,-ratio*dx, 0.,ratio,0.,-ratio*dy, 0.,0.,ratio,-ratio*dz).move_to(pose);
          else CImg<floatT>(4,3,1,1, 1,0,0,0, 0,1,0,0, 0,0,1,0).move_to(pose);
          if (pose_matrix) {
            CImg<floatT> pose0(pose_matrix,4,3,1,1,false);
            pose0.resize(4,4,1,1,0); pose.resize(4,4,1,1,0);
            pose0(3,3) = pose(3,3) = 1;
            (pose0*pose).get_crop(0,0,3,2).move_to(pose);
            Xoff = pose_matrix[12]; Yoff = pose_matrix[13]; Zoff = pose_matrix[14]; sprite_scale = pose_matrix[15];
          } else { Xoff = Yoff = Zoff = 0; sprite_scale = 1; }
          init_pose = false;
          redraw = true;
        }

        // Rotate and draw 3D object.
        if (redraw) {
          const float
            r00 = pose(0,0), r10 = pose(1,0), r20 = pose(2,0), r30 = pose(3,0),
            r01 = pose(0,1), r11 = pose(1,1), r21 = pose(2,1), r31 = pose(3,1),
            r02 = pose(0,2), r12 = pose(1,2), r22 = pose(2,2), r32 = pose(3,2);
          if ((clicked && nrender_motion>=0) || (!clicked && nrender_static>=0)) {
            const tp *const pv0 = vertices.data(), *const pv1 = vertices.data(0,1), *const pv2 = vertices.data(0,2);
            float
              *const prv0 = rotated_vertices.data(),
              *const prv1 = rotated_vertices.data(0,1),
              *const prv2 = rotated_vertices.data(0,2);
            cimg_pragma_openmp(parallel for cimg_openmp_if(vertices.width()>(cimg_openmp_sizefactor)*1024))
            cimg_forX(vertices,l) {
              const float x = (float)pv0[l], y = (float)pv1[l], z = (float)pv2[l];
              prv0[l] = r00*x + r10*y + r20*z + r30;
              prv1[l] = r01*x + r11*y + r21*z + r31;
              prv2[l] = r02*x + r12*y + r22*z + r32;
            }
          }
          else cimg_forX(bbox_vertices,l) {
              const float x = bbox_vertices(l,0), y = bbox_vertices(l,1), z = bbox_vertices(l,2);
              rotated_bbox_vertices(l,0) = r00*x + r10*y + r20*z + r30;
              rotated_bbox_vertices(l,1) = r01*x + r11*y + r21*z + r31;
              rotated_bbox_vertices(l,2) = r02*x + r12*y + r22*z + r32;
            }

          // Draw objects.
          const bool render_with_zbuffer = !clicked && nrender_static>0;
          visu = visu0;
          if ((clicked && nrender_motion<0) || (!clicked && nrender_static<0))
            visu.draw_object3d(Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                               rotated_bbox_vertices,bbox_primitives,bbox_colors,bbox_opacities,2,false,focal).
              draw_object3d(Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                            rotated_bbox_vertices,bbox_primitives,bbox_colors2,1,false,focal);
          else visu._draw_object3d(render_with_zbuffer?zbuffer.fill(0):CImg<floatT>::empty(),
                                   Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                                   rotated_vertices,reverse_primitives?reverse_primitives:primitives,
                                   colors,opacities,
                                   clicked?nrender_motion:nrender_static,
                                   _is_double_sided==1,focal,
                                   width()/2.f + light_x,height()/2.f + light_y,light_z + Zoff,
                                   specular_lightness,specular_shininess,1,sprite_scale,
                                   clicked);
          // Draw axes.
          if (ndisplay_axes) {
            const float
              n = 1e-8f + cimg::hypot(r00,r01,r02),
              _r00 = r00/n, _r10 = r10/n, _r20 = r20/n,
              _r01 = r01/n, _r11 = r11/n, _r21 = r21/n,
              _r02 = r01/n, _r12 = r12/n, _r22 = r22/n,
              Xaxes = 25, Yaxes = visu._height - 38.f;
            cimg_forX(axes_vertices,l) {
              const float
                x = axes_vertices(l,0),
                y = axes_vertices(l,1),
                z = axes_vertices(l,2);
              rotated_axes_vertices(l,0) = _r00*x + _r10*y + _r20*z;
              rotated_axes_vertices(l,1) = _r01*x + _r11*y + _r21*z;
              rotated_axes_vertices(l,2) = _r02*x + _r12*y + _r22*z;
            }
            axes_opacities(0,0) = (rotated_axes_vertices(1,2)>0)?0.5f:1.f;
            axes_opacities(1,0) = (rotated_axes_vertices(2,2)>0)?0.5f:1.f;
            axes_opacities(2,0) = (rotated_axes_vertices(3,2)>0)?0.5f:1.f;
            visu.draw_object3d(Xaxes,Yaxes,0,rotated_axes_vertices,axes_primitives,
                               axes_colors,axes_opacities,1,false,focal).
              draw_text((int)(Xaxes + rotated_axes_vertices(4,0)),
                        (int)(Yaxes + rotated_axes_vertices(4,1)),
                        "X",axes_colors[0]._data,0,axes_opacities(0,0),13).
              draw_text((int)(Xaxes + rotated_axes_vertices(5,0)),
                        (int)(Yaxes + rotated_axes_vertices(5,1)),
                        "Y",axes_colors[1]._data,0,axes_opacities(1,0),13).
              draw_text((int)(Xaxes + rotated_axes_vertices(6,0)),
                        (int)(Yaxes + rotated_axes_vertices(6,1)),
                        "Z",axes_colors[2]._data,0,axes_opacities(2,0),13);
          }
          visu.display(disp);
          if (!clicked || nrender_motion==nrender_static) redraw = false;
        }

        // Handle user interaction.
        if (!redraw) disp.wait();
        if ((disp.button() || disp.wheel()) && disp.mouse_x()>=0 && disp.mouse_y()>=0) {
          redraw = true;
          if (!clicked) { x0 = x1 = disp.mouse_x(); y0 = y1 = disp.mouse_y(); if (!disp.wheel()) clicked = true; }
          else { x1 = disp.mouse_x(); y1 = disp.mouse_y(); }
          const bool is_keyCTRL = disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT();
          if (disp.button()&1 && !is_keyCTRL) {
            const float
              R = 0.45f*std::min(disp.width(),disp.height()),
              R2 = R*R,
              u0 = (float)(x0 - disp.width()/2),
              v0 = (float)(y0 - disp.height()/2),
              u1 = (float)(x1 - disp.width()/2),
              v1 = (float)(y1 - disp.height()/2),
              n0 = cimg::hypot(u0,v0),
              n1 = cimg::hypot(u1,v1),
              nu0 = n0>R?(u0*R/n0):u0,
              nv0 = n0>R?(v0*R/n0):v0,
              nw0 = (float)std::sqrt(std::max(0.f,R2 - nu0*nu0 - nv0*nv0)),
              nu1 = n1>R?(u1*R/n1):u1,
              nv1 = n1>R?(v1*R/n1):v1,
              nw1 = (float)std::sqrt(std::max(0.f,R2 - nu1*nu1 - nv1*nv1)),
              u = nv0*nw1 - nw0*nv1,
              v = nw0*nu1 - nu0*nw1,
              w = nv0*nu1 - nu0*nv1,
              n = cimg::hypot(u,v,w),
              alpha = (float)std::asin(n/R2)*180/cimg::PI;
            (CImg<floatT>::rotation_matrix(u,v,w,-alpha)*pose).move_to(pose);
            x0 = x1; y0 = y1;
          }
          if (disp.button()&2 && !is_keyCTRL) {
            if (focal>0) Zoff-=(y0 - y1)*focal/400;
            else { const float s = std::exp((y0 - y1)/400.f); pose*=s; sprite_scale*=s; }
            x0 = x1; y0 = y1;
          }
          if (disp.wheel()) {
            if (focal>0) Zoff-=disp.wheel()*focal/20;
            else { const float s = std::exp(disp.wheel()/20.f); pose*=s; sprite_scale*=s; }
            disp.set_wheel();
          }
          if (disp.button()&4 || (disp.button()&1 && is_keyCTRL)) {
            Xoff+=(x1 - x0); Yoff+=(y1 - y0); x0 = x1; y0 = y1;
          }
          if ((disp.button()&1) && (disp.button()&2) && !is_keyCTRL) {
            init_pose = true; disp.set_button(); x0 = x1; y0 = y1;
            pose = CImg<floatT>(4,3,1,1, 1,0,0,0, 0,1,0,0, 0,0,1,0);
          }
        } else if (clicked) { x0 = x1; y0 = y1; clicked = false; redraw = true; }

        CImg<charT> filename(1024);
        switch (key = disp.key()) {
#if cimg_OS!=2
        case cimg::keyCTRLRIGHT :
#endif
        case 0 : case cimg::keyCTRLLEFT : key = 0; break;
        case cimg::keyD: if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                     CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false).
              _is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false)._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).resize(cimg_fitscreen(_width,_height,_depth),false)._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            if (!ns_width || !ns_height ||
                ns_width>(unsigned int)disp.screen_width() || ns_height>(unsigned int)disp.screen_height()) {
              ns_width = disp.screen_width()*3U/4;
              ns_height = disp.screen_height()*3U/4;
            }
            if (disp.is_fullscreen()) disp.resize(ns_width,ns_height,false);
            else {
              ns_width = disp._width; ns_height = disp._height;
              disp.resize(disp.screen_width(),disp.screen_height(),false);
            }
            disp.toggle_fullscreen()._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyT : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            // Switch single/double-sided primitives.
            if (--_is_double_sided==-2) _is_double_sided = 1;
            if (_is_double_sided>=0) reverse_primitives.assign();
            else primitives.get_reverse_object3d().move_to(reverse_primitives);
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyZ : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Enable/disable Z-buffer
            if (zbuffer) zbuffer.assign();
            else zbuffer.assign(visu0.width(),visu0.height(),1,1,0);
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyX : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Show/hide 3D axes
            ndisplay_axes = !ndisplay_axes;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF1 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to points
            nrender_motion = (nrender_static==0 && nrender_motion!=0)?0:-1; nrender_static = 0;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF2 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to lines
            nrender_motion = (nrender_static==1 && nrender_motion!=1)?1:-1; nrender_static = 1;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF3 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to flat
            nrender_motion = (nrender_static==2 && nrender_motion!=2)?2:-1; nrender_static = 2;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF4 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to flat-shaded
            nrender_motion = (nrender_static==3 && nrender_motion!=3)?3:-1; nrender_static = 3;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF5 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            // Set rendering mode to gouraud-shaded.
            nrender_motion = (nrender_static==4 && nrender_motion!=4)?4:-1; nrender_static = 4;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF6 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to phong-shaded
            nrender_motion = (nrender_static==5 && nrender_motion!=5)?5:-1; nrender_static = 5;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyS : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save snapshot
            static unsigned int snap_number = 0;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u."
#ifdef cimg_use_png
                            "png",
#else
                            "bmp",
#endif
                            snap_number++);
            } while (cimg::path_exists(filename));
            (+visu).__draw_text(" Saving snapshot... ",font_size,0).display(disp);
            visu.save(filename);
            (+visu).__draw_text(" Snapshot '%s' saved. ",font_size,0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyG : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .off file
            static unsigned int snap_number = 0;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.off",snap_number++);
            } while (cimg::path_exists(filename));
            (+visu).__draw_text(" Saving object... ",font_size,0).display(disp);
            vertices.save_off(reverse_primitives?reverse_primitives:primitives,colors,filename);
            (+visu).__draw_text(" Object '%s' saved. ",font_size,0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyO : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .cimg file
            static unsigned int snap_number = 0;
            do {

#ifdef cimg_use_zlib
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimgz",snap_number++);
#else
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimg",snap_number++);
#endif
            } while (cimg::path_exists(filename));
            (+visu).__draw_text(" Saving object... ",font_size,0).display(disp);
            vertices.get_object3dtoCImg3d(reverse_primitives?reverse_primitives:primitives,colors,opacities).
              save(filename);
            (+visu).__draw_text(" Object '%s' saved. ",font_size,0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        }
        if (disp.is_resized()) {
          disp.resize(false); visu0 = get_resize(disp,1);
          if (zbuffer) zbuffer.assign(disp.width(),disp.height());
          redraw = true;
        }
        if (!exit_on_anykey && key && key!=cimg::keyESC &&
            (key!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          key = 0;
        }
      }
      if (pose_matrix) {
        std::memcpy(pose_matrix,pose._data,12*sizeof(float));
        pose_matrix[12] = Xoff; pose_matrix[13] = Yoff; pose_matrix[14] = Zoff; pose_matrix[15] = sprite_scale;
      }
      disp.set_button().set_key(key);
      return *this;
    }

    //! Display 1D graph in an interactive window.
    /**
       \param disp Display window.
       \param plot_type Plot type. Can be <tt>{ 0=points | 1=segments | 2=splines | 3=bars }</tt>.
       \param vertex_type Vertex type.
       \param labelx Title for the horizontal axis, as a C-string.
       \param xmin Minimum value along the X-axis.
       \param xmax Maximum value along the X-axis.
       \param labely Title for the vertical axis, as a C-string.
       \param ymin Minimum value along the Y-axis.
       \param ymax Maximum value along the Y-axis.
       \param exit_on_anykey Exit function when any key is pressed.
    **/
    const CImg<T>& display_graph(CImgDisplay &disp,
                                 const unsigned int plot_type=1, const unsigned int vertex_type=1,
                                 const char *const labelx=0, const double xmin=0, const double xmax=0,
                                 const char *const labely=0, const double ymin=0, const double ymax=0,
                                 const bool exit_on_anykey=false) const {
      return _display_graph(disp,0,plot_type,vertex_type,labelx,xmin,xmax,labely,ymin,ymax,exit_on_anykey);
    }

    //! Display 1D graph in an interactive window \overload.
    const CImg<T>& display_graph(const char *const title=0,
                                 const unsigned int plot_type=1, const unsigned int vertex_type=1,
                                 const char *const labelx=0, const double xmin=0, const double xmax=0,
                                 const char *const labely=0, const double ymin=0, const double ymax=0,
                                 const bool exit_on_anykey=false) const {
      CImgDisplay disp;
      return _display_graph(disp,title,plot_type,vertex_type,labelx,xmin,xmax,labely,ymin,ymax,exit_on_anykey);
    }

    const CImg<T>& _display_graph(CImgDisplay &disp, const char *const title=0,
                                  const unsigned int plot_type=1, const unsigned int vertex_type=1,
                                  const char *const labelx=0, const double xmin=0, const double xmax=0,
                                  const char *const labely=0, const double ymin=0, const double ymax=0,
                                  const bool exit_on_anykey=false) const {
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "display_graph(): Empty instance.",
                                    cimg_instance);
      if (!disp) disp.assign(cimg_fitscreen(CImgDisplay::screen_width()/2,CImgDisplay::screen_height()/2,1),0,0).
                   set_title(title?"%s":"CImg<%s>",title?title:pixel_type());
      const ulongT siz = (ulongT)_width*_height*_depth, siz1 = std::max((ulongT)1,siz - 1);
      const unsigned int old_normalization = disp.normalization();
      disp.show().flush()._normalization = 0;

      double y0 = ymin, y1 = ymax, nxmin = xmin, nxmax = xmax;
      if (nxmin==nxmax) { nxmin = 0; nxmax = siz1; }
      int x0 = 0, x1 = width()*height()*depth() - 1, key = 0;

      for (bool reset_view = true; !key && !disp.is_closed(); ) {
        if (reset_view) { x0 = 0; x1 = width()*height()*depth() - 1; y0 = ymin; y1 = ymax; reset_view = false; }
        CImg<T> zoom(x1 - x0 + 1,1,1,spectrum());
        cimg_forC(*this,c) zoom.get_shared_channel(c) = CImg<T>(data(x0,0,0,c),x1 - x0 + 1,1,1,1,true);
        if (y0==y1) { y0 = zoom.min_max(y1); const double dy = y1 - y0; y0-=dy/20; y1+=dy/20; }
        if (y0==y1) { --y0; ++y1; }

        const CImg<intT> selection = zoom.get_select_graph(disp,plot_type,vertex_type,
                                                           labelx,
                                                           nxmin + x0*(nxmax - nxmin)/siz1,
                                                           nxmin + x1*(nxmax - nxmin)/siz1,
                                                           labely,y0,y1,true);
        const int mouse_x = disp.mouse_x(), mouse_y = disp.mouse_y();
        if (selection[0]>=0) {
          if (selection[2]<0) reset_view = true;
          else {
            x1 = x0 + selection[2]; x0+=selection[0];
            if (selection[1]>=0 && selection[3]>=0) {
              y0 = y1 - selection[3]*(y1 - y0)/(disp.height() - 32);
              y1-=selection[1]*(y1 - y0)/(disp.height() - 32);
            }
          }
        } else {
          bool go_in = false, go_out = false, go_left = false, go_right = false, go_up = false, go_down = false;
          switch (key = (int)disp.key()) {
          case cimg::keyHOME : reset_view = true; key = 0; disp.set_key(); break;
          case cimg::keyPADADD : go_in = true; go_out = false; key = 0; disp.set_key(); break;
          case cimg::keyPADSUB : go_out = true; go_in = false; key = 0; disp.set_key(); break;
          case cimg::keyARROWLEFT : case cimg::keyPAD4 : go_left = true; go_right = false; key = 0; disp.set_key();
            break;
          case cimg::keyARROWRIGHT : case cimg::keyPAD6 : go_right = true; go_left = false; key = 0; disp.set_key();
            break;
          case cimg::keyARROWUP : case cimg::keyPAD8 : go_up = true; go_down = false; key = 0; disp.set_key(); break;
          case cimg::keyARROWDOWN : case cimg::keyPAD2 : go_down = true; go_up = false; key = 0; disp.set_key(); break;
          case cimg::keyPAD7 : go_left = true; go_up = true; key = 0; disp.set_key(); break;
          case cimg::keyPAD9 : go_right = true; go_up = true; key = 0; disp.set_key(); break;
          case cimg::keyPAD1 : go_left = true; go_down = true; key = 0; disp.set_key(); break;
          case cimg::keyPAD3 : go_right = true; go_down = true; key = 0; disp.set_key(); break;
          }
          if (disp.wheel()) {
            if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) go_up = !(go_down = disp.wheel()<0);
            else if (disp.is_keySHIFTLEFT() || disp.is_keySHIFTRIGHT()) go_left = !(go_right = disp.wheel()>0);
            else go_out = !(go_in = disp.wheel()>0);
            key = 0;
          }

          if (go_in) {
            const int
              xsiz = x1 - x0,
              mx = (mouse_x - 16)*xsiz/(disp.width() - 32),
              cx = x0 + cimg::cut(mx,0,xsiz);
            if (x1 - x0>4) {
              x0 = cx - 7*(cx - x0)/8; x1 = cx + 7*(x1 - cx)/8;
              if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
                const double
                  ysiz = y1 - y0,
                  my = (mouse_y - 16)*ysiz/(disp.height() - 32),
                  cy = y1 - cimg::cut(my,0.,ysiz);
                y0 = cy - 7*(cy - y0)/8; y1 = cy + 7*(y1 - cy)/8;
              } else y0 = y1 = 0;
            }
          }
          if (go_out) {
            if (x0>0 || x1<(int)siz1) {
              const int delta_x = (x1 - x0)/8, ndelta_x = delta_x?delta_x:(siz>1);
              const double ndelta_y = (y1 - y0)/8;
              x0-=ndelta_x; x1+=ndelta_x;
              y0-=ndelta_y; y1+=ndelta_y;
              if (x0<0) { x1-=x0; x0 = 0; if (x1>=(int)siz) x1 = (int)siz1; }
              if (x1>=(int)siz) { x0-=(x1 - siz1); x1 = (int)siz1; if (x0<0) x0 = 0; }
            }
          }
          if (go_left) {
            const int delta = (x1 - x0)/5, ndelta = delta?delta:1;
            if (x0 - ndelta>=0) { x0-=ndelta; x1-=ndelta; }
            else { x1-=x0; x0 = 0; }
            go_left = false;
          }
          if (go_right) {
            const int delta = (x1 - x0)/5, ndelta = delta?delta:1;
            if (x1 + ndelta<(int)siz) { x0+=ndelta; x1+=ndelta; }
            else { x0+=(siz1 - x1); x1 = (int)siz1; }
            go_right = false;
          }
          if (go_up) {
            const double delta = (y1 - y0)/10, ndelta = delta?delta:1;
            y0+=ndelta; y1+=ndelta;
            go_up = false;
          }
          if (go_down) {
            const double delta = (y1 - y0)/10, ndelta = delta?delta:1;
            y0-=ndelta; y1-=ndelta;
            go_down = false;
          }
        }
        if (!exit_on_anykey && key && key!=(int)cimg::keyESC &&
            (key!=(int)cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          disp.set_key(key,false);
          key = 0;
        }
      }
      disp._normalization = old_normalization;
      return *this;
    }

    //! Save the image as a file.
    /**
       \param filename Filename, as a C-string.
       \param number When positive, represents an index added to the filename. Otherwise, no number is added.
       \param digits Number of digits used for adding the number to the filename.
       \note
       - The used file format is defined by the file extension in the filename \p filename.
       - Parameter \p number can be used to add a 6-digit number to the filename before saving.

    **/
    const CImg<T>& save(const char *const filename, const int number=-1, const unsigned int digits=6) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save(): Specified filename is (null).",
                                    cimg_instance);
      // Do not test for empty instances, since .cimg format is able to manage empty instances.
      const bool is_stdout = *filename=='-' && (!filename[1] || filename[1]=='.');
      const char *const ext = cimg::split_filename(filename);
      CImg<charT> nfilename(1024);
      const char *const fn = is_stdout?filename:(number>=0)?cimg::number_filename(filename,number,digits,nfilename):
        filename;

#ifdef cimg_save_plugin
      cimg_save_plugin(fn);
#endif
#ifdef cimg_save_plugin1
      cimg_save_plugin1(fn);
#endif
#ifdef cimg_save_plugin2
      cimg_save_plugin2(fn);
#endif
#ifdef cimg_save_plugin3
      cimg_save_plugin3(fn);
#endif
#ifdef cimg_save_plugin4
      cimg_save_plugin4(fn);
#endif
#ifdef cimg_save_plugin5
      cimg_save_plugin5(fn);
#endif
#ifdef cimg_save_plugin6
      cimg_save_plugin6(fn);
#endif
#ifdef cimg_save_plugin7
      cimg_save_plugin7(fn);
#endif
#ifdef cimg_save_plugin8
      cimg_save_plugin8(fn);
#endif
      // Text formats.
      if (!cimg::strcasecmp(ext,"asc")) return save_ascii(fn);
      else if (!cimg::strcasecmp(ext,"csv") ||
               !cimg::strcasecmp(ext,"dlm") ||
               !cimg::strcasecmp(ext,"txt")) return save_dlm(fn);
      else if (!cimg::strcasecmp(ext,"cpp") ||
               !cimg::strcasecmp(ext,"hpp") ||
               !cimg::strcasecmp(ext,"h") ||
               !cimg::strcasecmp(ext,"c")) return save_cpp(fn);

      // 2D binary formats.
      else if (!cimg::strcasecmp(ext,"bmp")) return save_bmp(fn);
      else if (!cimg::strcasecmp(ext,"jpg") ||
               !cimg::strcasecmp(ext,"jpeg") ||
               !cimg::strcasecmp(ext,"jpe") ||
               !cimg::strcasecmp(ext,"jfif") ||
               !cimg::strcasecmp(ext,"jif")) return save_jpeg(fn);
      else if (!cimg::strcasecmp(ext,"rgb")) return save_rgb(fn);
      else if (!cimg::strcasecmp(ext,"rgba")) return save_rgba(fn);
      else if (!cimg::strcasecmp(ext,"png")) return save_png(fn);
      else if (!cimg::strcasecmp(ext,"pgm") ||
               !cimg::strcasecmp(ext,"ppm") ||
               !cimg::strcasecmp(ext,"pnm")) return save_pnm(fn);
      else if (!cimg::strcasecmp(ext,"pnk")) return save_pnk(fn);
      else if (!cimg::strcasecmp(ext,"pfm")) return save_pfm(fn);
      else if (!cimg::strcasecmp(ext,"exr")) return save_exr(fn);
      else if (!cimg::strcasecmp(ext,"tif") ||
               !cimg::strcasecmp(ext,"tiff")) return save_tiff(fn);
      else if (!cimg::strcasecmp(ext,"webp")) return save_webp(fn);
      else if (!cimg::strcasecmp(ext,"jxl")) return save_jxl(fn);

      // 3D binary formats.
      else if (!*ext) {
#ifdef cimg_use_zlib
        return save_cimg(fn,true);
#else
        return save_cimg(fn,false);
#endif
      } else if (!cimg::strcasecmp(ext,"cimgz")) return save_cimg(fn,true);
      else if (!cimg::strcasecmp(ext,"cimg")) return save_cimg(fn,false);
      else if (!cimg::strcasecmp(ext,"dcm")) return save_medcon_external(fn);
      else if (!cimg::strcasecmp(ext,"hdr") ||
               !cimg::strcasecmp(ext,"nii")) return save_analyze(fn);
      else if (!cimg::strcasecmp(ext,"inr")) return save_inr(fn);
      else if (!cimg::strcasecmp(ext,"mnc")) return save_minc2(fn);
      else if (!cimg::strcasecmp(ext,"pan")) return save_pandore(fn);
      else if (!cimg::strcasecmp(ext,"raw")) return save_raw(fn);

      // Archive files.
      else if (!cimg::strcasecmp(ext,"gz")) return save_gzip_external(fn);

      // Image sequences.
      else if (!cimg::strcasecmp(ext,"yuv")) return save_yuv(fn,444,true);
      else if (!cimg::strcasecmp(ext,"avi") ||
               !cimg::strcasecmp(ext,"mov") ||
               !cimg::strcasecmp(ext,"asf") ||
               !cimg::strcasecmp(ext,"divx") ||
               !cimg::strcasecmp(ext,"flv") ||
               !cimg::strcasecmp(ext,"mpg") ||
               !cimg::strcasecmp(ext,"m1v") ||
               !cimg::strcasecmp(ext,"m2v") ||
               !cimg::strcasecmp(ext,"m4v") ||
               !cimg::strcasecmp(ext,"mjp") ||
               !cimg::strcasecmp(ext,"mp4") ||
               !cimg::strcasecmp(ext,"mkv") ||
               !cimg::strcasecmp(ext,"mpe") ||
               !cimg::strcasecmp(ext,"movie") ||
               !cimg::strcasecmp(ext,"ogm") ||
               !cimg::strcasecmp(ext,"ogg") ||
               !cimg::strcasecmp(ext,"ogv") ||
               !cimg::strcasecmp(ext,"qt") ||
               !cimg::strcasecmp(ext,"rm") ||
               !cimg::strcasecmp(ext,"vob") ||
               !cimg::strcasecmp(ext,"webm") ||
               !cimg::strcasecmp(ext,"wmv") ||
               !cimg::strcasecmp(ext,"xvid") ||
               !cimg::strcasecmp(ext,"mpeg")) return save_video(fn);
      return save_other(fn);
    }

    //! Save the image as an ASCII file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_ascii(const char *const filename) const {
      return _save_ascii(0,filename);
    }

    //! Save the image as an ASCII file \overload.
    const CImg<T>& save_ascii(std::FILE *const file) const {
      return _save_ascii(file,0);
    }

    const CImg<T>& _save_ascii(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_ascii(): Specified filename is (null).",
                                    cimg_instance);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"w");
      std::fprintf(nfile,"%u %u %u %u\n",_width,_height,_depth,_spectrum);
      const T* ptrs = _data;
      cimg_forYZC(*this,y,z,c) {
        cimg_forX(*this,x) std::fprintf(nfile,"%.17g ",(double)*(ptrs++));
        std::fputc('\n',nfile);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a .cpp source file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_cpp(const char *const filename) const {
      return _save_cpp(0,filename);
    }

    //! Save the image as a .cpp source file \overload.
    const CImg<T>& save_cpp(std::FILE *const file) const {
      return _save_cpp(file,0);
    }

    const CImg<T>& _save_cpp(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_cpp(): Specified filename is (null).",
                                    cimg_instance);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"w");
      CImg<charT> varname(1024); *varname = 0;
      if (filename) cimg_sscanf(cimg::basename(filename),"%1023[a-zA-Z0-9_]",varname._data);
      if (!*varname) cimg_snprintf(varname,varname._width,"unnamed");
      std::fprintf(nfile,
                   "/* Define image '%s' of size %ux%ux%ux%u and type '%s' */\n"
                   "%s data_%s[] = { %s\n  ",
                   varname._data,_width,_height,_depth,_spectrum,pixel_type(),pixel_type(),varname._data,
                   is_empty()?"};":"");
      if (!is_empty()) for (ulongT off = 0, siz = size() - 1; off<=siz; ++off) {
        std::fprintf(nfile,cimg::type<T>::format(),cimg::type<T>::format((*this)[off]));
        if (off==siz) std::fprintf(nfile," };\n");
        else if (!((off + 1)%16)) std::fprintf(nfile,",\n  ");
        else std::fprintf(nfile,", ");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a DLM file.
    /**
       \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_dlm(const char *const filename) const {
      return _save_dlm(0,filename);
    }

    //! Save the image as a DLM file \overload.
    const CImg<T>& save_dlm(std::FILE *const file) const {
      return _save_dlm(file,0);
    }

    const CImg<T>& _save_dlm(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_dlm(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_dlm(): Instance is volumetric, values along Z will be unrolled in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (_spectrum>1)
        cimg::warn(_cimg_instance
                   "save_dlm(): Instance is multispectral, values along C will be unrolled in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"w");
      const T* ptrs = _data;
      cimg_forYZC(*this,y,z,c) {
        cimg_forX(*this,x) std::fprintf(nfile,"%.17g%s",(double)*(ptrs++),(x==width() - 1)?"":",");
        std::fputc('\n',nfile);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a BMP file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_bmp(const char *const filename) const {
      return _save_bmp(0,filename);
    }

    //! Save the image as a BMP file \overload.
    const CImg<T>& save_bmp(std::FILE *const file) const {
      return _save_bmp(file,0);
    }

    const CImg<T>& _save_bmp(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_bmp(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_bmp(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (_spectrum>3)
        cimg::warn(_cimg_instance
                   "save_bmp(): Instance is multispectral, only the three first channels will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      CImg<ucharT> header(54,1,1,1,0);
      unsigned char align_buf[4] = {};
      const unsigned int
        align = (4 - (3*_width)%4)%4,
        buf_size = (3*_width + align)*height(),
        file_size = 54 + buf_size;
      header[0] = 'B'; header[1] = 'M';
      header[0x02] = file_size&0xFF;
      header[0x03] = (file_size>>8)&0xFF;
      header[0x04] = (file_size>>16)&0xFF;
      header[0x05] = (file_size>>24)&0xFF;
      header[0x0A] = 0x36;
      header[0x0E] = 0x28;
      header[0x12] = _width&0xFF;
      header[0x13] = (_width>>8)&0xFF;
      header[0x14] = (_width>>16)&0xFF;
      header[0x15] = (_width>>24)&0xFF;
      header[0x16] = _height&0xFF;
      header[0x17] = (_height>>8)&0xFF;
      header[0x18] = (_height>>16)&0xFF;
      header[0x19] = (_height>>24)&0xFF;
      header[0x1A] = 1;
      header[0x1B] = 0;
      header[0x1C] = 24;
      header[0x1D] = 0;
      header[0x22] = buf_size&0xFF;
      header[0x23] = (buf_size>>8)&0xFF;
      header[0x24] = (buf_size>>16)&0xFF;
      header[0x25] = (buf_size>>24)&0xFF;
      header[0x27] = 0x1;
      header[0x2B] = 0x1;
      cimg::fwrite(header._data,54,nfile);

      const T
        *ptr_r = data(0,_height - 1,0,0),
        *ptr_g = (_spectrum>=2)?data(0,_height - 1,0,1):0,
        *ptr_b = (_spectrum>=3)?data(0,_height - 1,0,2):0;

      switch (_spectrum) {
      case 1 : {
        cimg_forY(*this,y) {
          cimg_forX(*this,x) {
            const unsigned char val = (unsigned char)*(ptr_r++);
            std::fputc(val,nfile); std::fputc(val,nfile); std::fputc(val,nfile);
          }
          cimg::fwrite(align_buf,align,nfile);
          ptr_r-=2*_width;
        }
      } break;
      case 2 : {
        cimg_forY(*this,y) {
          cimg_forX(*this,x) {
            std::fputc(0,nfile);
            std::fputc((unsigned char)(*(ptr_g++)),nfile);
            std::fputc((unsigned char)(*(ptr_r++)),nfile);
          }
          cimg::fwrite(align_buf,align,nfile);
          ptr_r-=2*_width; ptr_g-=2*_width;
        }
      } break;
      default : {
        cimg_forY(*this,y) {
          cimg_forX(*this,x) {
            std::fputc((unsigned char)(*(ptr_b++)),nfile);
            std::fputc((unsigned char)(*(ptr_g++)),nfile);
            std::fputc((unsigned char)(*(ptr_r++)),nfile);
          }
          cimg::fwrite(align_buf,align,nfile);
          ptr_r-=2*_width; ptr_g-=2*_width; ptr_b-=2*_width;
        }
      }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a WebP file.
    /**
      \param filename Filename, as a C-string.
      \param quality Image quality (in %)
    **/
    const CImg<T>& save_webp(const char *const filename, const int quality=100) const {
      return _save_webp(filename,quality);
    }

    const CImg<T>& _save_webp(const char *const filename, const int quality) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_webp(): Specified filename is (null).",
                                    cimg_instance);
      if (_spectrum!=3 && _spectrum!=4)
        throw CImgArgumentException(_cimg_instance
                                    "save_webp(): WebP only supports (A)RGB colorspace.",
                                    cimg_instance);
#ifndef cimg_use_webp
      cimg::unused(quality);
      return save_other(filename);
#else
      std::FILE *file = cimg::fopen(filename, "wb");
      CImg<uint8_t> rgbaBuffer(size());
      T *ptr_r = _data, *ptr_g = _data + 1UL*_width*_height,
        *ptr_b = _data + 2UL*_width*_height, *ptr_a = _spectrum==3?NULL:_data + 3UL*_width*_height;
      uint8_t *ptr = rgbaBuffer._data;
      cimg_forY(*this,y) {
        cimg_forX(*this,x) {
          *(ptr++) = (T)*(ptr_r++);
          *(ptr++) = (T)*(ptr_g++);
          *(ptr++) = (T)*(ptr_b++);
          if (ptr_a) *(ptr++) = (T)*(ptr_a++);
        }
      }
      uint8_t *imgData = NULL;
      const int stride = _width*_spectrum*sizeof(uint8_t);
      size_t size = 0;
      if (_spectrum==3) {
        size = WebPEncodeRGB(rgbaBuffer._data, _width, _height, stride, (float)quality, &imgData);
      } else {
        size = WebPEncodeRGBA(rgbaBuffer._data, _width, _height, stride, (float)quality, &imgData);
      }
      if (!imgData) {
        throw CImgIOException(_cimg_instance
                              "save_webp(): Failed to encode image to file '%s'.",
                              cimg_instance,
                              filename);
      }
      cimg::fwrite(imgData, size, file);
      cimg::fclose(file);
      WebPFree(imgData);
      return *this;
#endif
    }

    //! Save the image as a JPEG file.
    /**
      \param filename Filename, as a C-string.
      \param quality Image quality (in %)
    **/
    const CImg<T>& save_jpeg(const char *const filename, const unsigned int quality=100) const {
      return _save_jpeg(0,filename,quality);
    }

    //! Save the image as a JPEG file \overload.
    const CImg<T>& save_jpeg(std::FILE *const file, const unsigned int quality=100) const {
      return _save_jpeg(file,0,quality);
    }

    const CImg<T>& _save_jpeg(std::FILE *const file, const char *const filename, const unsigned int quality) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_jpeg(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_jpeg(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

#ifndef cimg_use_jpeg
      if (!file) return save_other(filename,quality);
      else throw CImgIOException(_cimg_instance
                                 "save_jpeg(): Unable to save data in '(*FILE)' unless libjpeg is enabled.",
                                 cimg_instance);
#else
      unsigned int dimbuf = 0;
      J_COLOR_SPACE colortype = JCS_RGB;

      switch (_spectrum) {
      case 1 : dimbuf = 1; colortype = JCS_GRAYSCALE; break;
      case 2 : dimbuf = 3; colortype = JCS_RGB; break;
      case 3 : dimbuf = 3; colortype = JCS_RGB; break;
      default : dimbuf = 4; colortype = JCS_CMYK; break;
      }

      // Call libjpeg functions.
      struct jpeg_compress_struct cinfo;
      struct jpeg_error_mgr jerr;
      cinfo.err = jpeg_std_error(&jerr);
      jpeg_create_compress(&cinfo);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      jpeg_stdio_dest(&cinfo,nfile);
      cinfo.image_width = _width;
      cinfo.image_height = _height;
      cinfo.input_components = dimbuf;
      cinfo.in_color_space = colortype;
      jpeg_set_defaults(&cinfo);
      jpeg_set_quality(&cinfo,quality<100?quality:100,TRUE);
      jpeg_start_compress(&cinfo,TRUE);

      JSAMPROW row_pointer[1];
      CImg<ucharT> buffer(_width*dimbuf);

      while (cinfo.next_scanline<cinfo.image_height) {
        unsigned char *ptrd = buffer._data;

        // Fill pixel buffer.
        switch (_spectrum) {
        case 1 : { // Greyscale images
          const T *ptr_g = data(0, cinfo.next_scanline);
          for (unsigned int b = 0; b<cinfo.image_width; b++)
            *(ptrd++) = (unsigned char)*(ptr_g++);
        } break;
        case 2 : { // RG images
          const T *ptr_r = data(0,cinfo.next_scanline,0,0),
            *ptr_g = data(0,cinfo.next_scanline,0,1);
          for (unsigned int b = 0; b<cinfo.image_width; ++b) {
            *(ptrd++) = (unsigned char)*(ptr_r++);
            *(ptrd++) = (unsigned char)*(ptr_g++);
            *(ptrd++) = 0;
          }
        } break;
        case 3 : { // RGB images
          const T *ptr_r = data(0,cinfo.next_scanline,0,0),
            *ptr_g = data(0,cinfo.next_scanline,0,1),
            *ptr_b = data(0,cinfo.next_scanline,0,2);
          for (unsigned int b = 0; b<cinfo.image_width; ++b) {
            *(ptrd++) = (unsigned char)*(ptr_r++);
            *(ptrd++) = (unsigned char)*(ptr_g++);
            *(ptrd++) = (unsigned char)*(ptr_b++);
          }
        } break;
        default : { // CMYK images
          const T *ptr_r = data(0,cinfo.next_scanline,0,0),
            *ptr_g = data(0,cinfo.next_scanline,0,1),
            *ptr_b = data(0,cinfo.next_scanline,0,2),
            *ptr_a = data(0,cinfo.next_scanline,0,3);
          for (unsigned int b = 0; b<cinfo.image_width; ++b) {
            *(ptrd++) = (unsigned char)*(ptr_r++);
            *(ptrd++) = (unsigned char)*(ptr_g++);
            *(ptrd++) = (unsigned char)*(ptr_b++);
            *(ptrd++) = (unsigned char)*(ptr_a++);
          }
        }
        }
        *row_pointer = buffer._data;
        jpeg_write_scanlines(&cinfo,row_pointer,1);
      }
      jpeg_finish_compress(&cinfo);
      if (!file) cimg::fclose(nfile);
      jpeg_destroy_compress(&cinfo);
      return *this;
#endif
    }

    //! Save the image as a JPEG XL file.
    /**
      \param filename Filename, as a C-string.
      \param distance Sets the level for lossy compression: lower = higher quality.
        Range: 0 .. 25. 0.0 = mathematically lossless
      \param bytes_per_pixel Force the number of bytes per pixels for the saving, when possible.
    **/
    const CImg<T>& save_jxl(const char *const filename, const float distance=1.0f,
                            const unsigned int bytes_per_pixel=0) const {
      return _save_jxl(filename,distance,bytes_per_pixel);
    }

    const CImg<T>& _save_jxl(const char *const filename, const float distance=1.0f,
                             const unsigned int bytes_per_pixel=0) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_jxl(): Specified filename is (null).",
                                    cimg_instance);
      if (_spectrum > 4)
        throw CImgArgumentException(_cimg_instance
                                    "save_jxl(): JPEG XL only supports at most 4 channels.",
                                    cimg_instance);
      double stmin, stmax = (double)max_min(stmin);
      if (stmin<0 || (bytes_per_pixel==1 && stmax>=256) || stmax>=65536)
        cimg::warn(_cimg_instance
                   "save_jxl(): Instance has pixel values in [%g,%g], probable type overflow in file '%s'.",
                   cimg_instance,
                   stmin,stmax,filename);
      if (bytes_per_pixel>2 || sizeof(T)<bytes_per_pixel)
        throw CImgArgumentException(_cimg_instance
                                    "save_jxl(): bytes_per_pixel must be in [0, 2] and less than or equal to sizeof(T)",
                                    cimg_instance);
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_jxl(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename);
#ifndef cimg_use_jxl
      cimg::unused(distance);
      return save_other(filename);
#else
      std::FILE *file = cimg::fopen(filename, "wb");
      cimg_uint32 nChannels = _spectrum;
      bool hasAlpha = _spectrum==2 || _spectrum==4;
      if (hasAlpha) --nChannels;
      unsigned int bytesPerPixel = bytes_per_pixel;
      if (bytesPerPixel==0)
          bytesPerPixel = stmax<256?1:2;
      CImg<ucharT> rgbBuffer(_width*_height*nChannels*bytesPerPixel);
      const T *ptr_r = 0, *ptr_g = 0, *ptr_b = 0, *ptr_a = 0;
      switch (_spectrum) {
      case 1:
        ptr_r = data(0,0,0,0);
        break;
      case 2:
        ptr_r = data(0,0,0,0);
        ptr_a = data(0,0,0,1);
        break;
      case 3:
        ptr_r = data(0,0,0,0);
        ptr_g = data(0,0,0,1);
        ptr_b = data(0,0,0,2);
        break;
      case 4:
        ptr_r = data(0,0,0,0);
        ptr_g = data(0,0,0,1);
        ptr_b = data(0,0,0,2);
        ptr_a = data(0,0,0,3);
        break;
      }
      switch (bytesPerPixel) {
      case 1: {
        unsigned char *ptr = (unsigned char*)rgbBuffer._data;
        cimg_forXY(*this,x,y) {
          *(ptr++) = (unsigned char)*(ptr_r++);
          if (ptr_g) *(ptr++) = (unsigned char)*(ptr_g++);
          if (ptr_b) *(ptr++) = (unsigned char)*(ptr_b++);
        }
      } break;
      case 2: {
        cimg_uint16 *ptr = (cimg_uint16*)rgbBuffer._data;
        cimg_forXY(*this,x,y) {
          *(ptr++) = (cimg_uint16)*(ptr_r++);
          if (ptr_g) *(ptr++) = (cimg_uint16)*(ptr_g++);
          if (ptr_b) *(ptr++) = (cimg_uint16)*(ptr_b++);
        }
      } break;
      }

      JxlEncoder *encoder = JxlEncoderCreate(NULL);

      JxlDataType dataType = bytesPerPixel==2?JXL_TYPE_UINT16:JXL_TYPE_UINT8;
      JxlPixelFormat pixelFormat = {
        nChannels,
        dataType,
        cimg::endianness()?JXL_BIG_ENDIAN:JXL_LITTLE_ENDIAN,
        0,
      };
      JxlBasicInfo basicInfo;
      JxlEncoderInitBasicInfo(&basicInfo);
      basicInfo.bits_per_sample = bytesPerPixel*8;
      basicInfo.exponent_bits_per_sample = 0;
      basicInfo.xsize = _width;
      basicInfo.ysize = _height;
      basicInfo.uses_original_profile = JXL_FALSE;
      if (hasAlpha) {
        basicInfo.alpha_bits = bytesPerPixel*8;
        basicInfo.alpha_exponent_bits = 0;
        basicInfo.num_extra_channels = 1;
      }
      basicInfo.num_color_channels = nChannels;
      if (JXL_ENC_SUCCESS!=JxlEncoderSetBasicInfo(encoder,&basicInfo)) {
        cimg::fclose(file);
        JxlEncoderDestroy(encoder);
        throw CImgIOException(_cimg_instance
                              "save_jxl(): Failed to set basic info when saving file '%s'.",
                              cimg_instance,
                              filename);
      }

      JxlColorEncoding colorEncoding = {};
      JXL_BOOL isGray = pixelFormat.num_channels<3?JXL_TRUE:JXL_FALSE;
      JxlColorEncodingSetToSRGB(&colorEncoding, isGray);
      if (JXL_ENC_SUCCESS!=JxlEncoderSetColorEncoding(encoder,&colorEncoding)) {
        cimg::fclose(file);
        JxlEncoderDestroy(encoder);
        throw CImgIOException(_cimg_instance
                              "save_jxl(): Failed to set color encoding when saving file '%s'.",
                              cimg_instance,
                              filename);
      }

      JxlEncoderFrameSettings* frameSettings = JxlEncoderFrameSettingsCreate(encoder,NULL);
      if (JXL_ENC_SUCCESS!=JxlEncoderSetFrameDistance(frameSettings,distance)) {
        cimg::fclose(file);
        JxlEncoderDestroy(encoder);
        throw CImgIOException(_cimg_instance
                              "save_jxl(): Failed to set lossy compression level when saving file '%s'.",
                              cimg_instance,
                              filename);
      }
      if (JXL_ENC_SUCCESS!=JxlEncoderAddImageFrame(frameSettings,&pixelFormat,(const void*)rgbBuffer._data,
                                                   rgbBuffer.size())) {
        cimg::fclose(file);
        JxlEncoderDestroy(encoder);
        throw CImgIOException(_cimg_instance
                              "save_jxl(): Failed to set image data when saving file '%s'.",
                              cimg_instance,
                              filename);
      }

      CImg<ucharT> alphaBuffer;
      if (hasAlpha) {
        ucharT *alphaPtr = (ucharT*)ptr_a;
        if (sizeof(T)!=bytesPerPixel) {
          alphaBuffer.assign(_width*_height*bytesPerPixel);
          switch (bytesPerPixel) {
          case 1: {
            unsigned char *ptr = (unsigned char*)alphaBuffer._data;
            cimg_forY(*this,y) {
              cimg_forX(*this,x) {
                *(ptr++) = (unsigned char)*(ptr_a++);
              }
            }
          } break;
          case 2: {
            cimg_uint16 *ptr = (cimg_uint16*)alphaBuffer._data;
            cimg_forY(*this,y) {
              cimg_forX(*this,x) {
                *(ptr++) = (cimg_uint16)*(ptr_a++);
              }
            }
          } break;
          }
          alphaPtr = (ucharT*)alphaBuffer._data;
        }
        if (JXL_ENC_SUCCESS!=JxlEncoderSetExtraChannelBuffer(frameSettings,&pixelFormat,(const void*)alphaPtr,
                                                             _width*_height*bytesPerPixel,0)) {
          cimg::fclose(file);
          JxlEncoderDestroy(encoder);
          throw CImgIOException(_cimg_instance
                                "save_jxl(): Failed to set alpha channel when saving file '%s'.",
                                cimg_instance,
                                filename);
        }
      }
      JxlEncoderCloseInput(encoder);

      CImg<cimg_uint8> compressed(1024);
      cimg_uint8 *nextOut = compressed.data();
      size_t availOut = compressed.size() - (nextOut - compressed.data());
      JxlEncoderStatus processResult = JXL_ENC_NEED_MORE_OUTPUT;
      while (processResult==JXL_ENC_NEED_MORE_OUTPUT) {
        processResult = JxlEncoderProcessOutput(encoder,&nextOut,&availOut);
        if (processResult==JXL_ENC_NEED_MORE_OUTPUT) {
          size_t offset = nextOut - compressed.data();
          compressed.resize(compressed.size()*2,1,1,1,-1);
          nextOut = compressed.data() + offset;
          availOut = compressed.size() - offset;
        }
      }
      compressed.resize(nextOut - compressed.data(),1,1,1,-1);
      if (JXL_ENC_SUCCESS!=processResult) {
        cimg::fclose(file);
        JxlEncoderDestroy(encoder);
        throw CImgIOException(_cimg_instance
                              "save_jxl(): Failed to encode image data when saving file '%s'.",
                              cimg_instance,
                              filename);
      }

      cimg::fwrite(compressed.data(),compressed.size(),file);
      cimg::fclose(file);
      JxlEncoderDestroy(encoder);
      return *this;
#endif
    }

    //! Save the image, using built-in ImageMagick++ library.
    /**
      \param filename Filename, as a C-string.
      \param bytes_per_pixel Force the number of bytes per pixel for the saving, when possible.
    **/
    const CImg<T>& save_magick(const char *const filename, const unsigned int bytes_per_pixel=0) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_magick(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

#ifdef cimg_use_magick
      double stmin, stmax = (double)max_min(stmin);
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_magick(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename);

      if (_spectrum>3)
        cimg::warn(_cimg_instance
                   "save_magick(): Instance is multispectral, only the three first channels will be "
                   "saved in file '%s'.",
                   cimg_instance,
                   filename);

      if (stmin<0 || (bytes_per_pixel==1 && stmax>=256) || stmax>=65536)
        cimg::warn(_cimg_instance
                   "save_magick(): Instance has pixel values in [%g,%g], probable type overflow in file '%s'.",
                   cimg_instance,
                   stmin,stmax,filename);

      Magick::Image image(Magick::Geometry(_width,_height),"black");
      image.type(Magick::TrueColorType);
      image.depth(bytes_per_pixel?(8*bytes_per_pixel):(stmax>=256?16:8));
      const T
        *ptr_r = data(0,0,0,0),
        *ptr_g = _spectrum>1?data(0,0,0,1):0,
        *ptr_b = _spectrum>2?data(0,0,0,2):0;
      Magick::PixelPacket *pixels = image.getPixels(0,0,_width,_height);
      switch (_spectrum) {
      case 1 : // Scalar images
        for (ulongT off = (ulongT)_width*_height; off; --off) {
          pixels->red = pixels->green = pixels->blue = (Magick::Quantum)*(ptr_r++);
          ++pixels;
        }
        break;
      case 2 : // RG images
        for (ulongT off = (ulongT)_width*_height; off; --off) {
          pixels->red = (Magick::Quantum)*(ptr_r++);
          pixels->green = (Magick::Quantum)*(ptr_g++);
          pixels->blue = 0; ++pixels;
        }
        break;
      default : // RGB images
        for (ulongT off = (ulongT)_width*_height; off; --off) {
          pixels->red = (Magick::Quantum)*(ptr_r++);
          pixels->green = (Magick::Quantum)*(ptr_g++);
          pixels->blue = (Magick::Quantum)*(ptr_b++);
          ++pixels;
        }
      }
      image.syncPixels();
      image.write(filename);
      return *this;
#else
      cimg::unused(bytes_per_pixel);
      throw CImgIOException(_cimg_instance
                            "save_magick(): Unable to save file '%s' unless libMagick++ is enabled.",
                            cimg_instance,
                            filename);
#endif
    }

    //! Save the image as a PNG file.
    /**
       \param filename Filename, as a C-string.
       \param bytes_per_pixel Force the number of bytes per pixels for the saving, when possible.
    **/
    const CImg<T>& save_png(const char *const filename, const unsigned int bytes_per_pixel=0) const {
      return _save_png(0,filename,bytes_per_pixel);
    }

    //! Save the image as a PNG file \overload.
    const CImg<T>& save_png(std::FILE *const file, const unsigned int bytes_per_pixel=0) const {
      return _save_png(file,0,bytes_per_pixel);
    }

    const CImg<T>& _save_png(std::FILE *const file, const char *const filename,
                             const unsigned int bytes_per_pixel=0) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_png(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }

#ifndef cimg_use_png
      cimg::unused(bytes_per_pixel);
      if (!file) return save_other(filename);
      else throw CImgIOException(_cimg_instance
                                 "save_png(): Unable to save data in '(*FILE)' unless libpng is enabled.",
                                 cimg_instance);
#else

#if defined __GNUC__
      const char *volatile nfilename = filename; // Use 'volatile' to avoid (wrong) g++ warning
      std::FILE *volatile nfile = file?file:cimg::fopen(nfilename,"wb");
      volatile double stmin, stmax = (double)max_min(stmin);
#else
      const char *nfilename = filename;
      std::FILE *nfile = file?file:cimg::fopen(nfilename,"wb");
      double stmin, stmax = (double)max_min(stmin);
#endif

      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_png(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename);

      if (_spectrum>4)
        cimg::warn(_cimg_instance
                   "save_png(): Instance is multispectral, only the three first channels will be saved in file '%s'.",
                   cimg_instance,
                   filename);

      if (stmin<0 || (bytes_per_pixel==1 && stmax>=256) || stmax>=65536)
        cimg::warn(_cimg_instance
                   "save_png(): Instance has pixel values in [%g,%g], probable type overflow in file '%s'.",
                   cimg_instance,
                   stmin,stmax,filename);

      // Setup PNG structures for write.
      png_voidp user_error_ptr = 0;
      png_error_ptr user_error_fn = 0, user_warning_fn = 0;
      png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,user_error_ptr, user_error_fn,
                                                    user_warning_fn);
      if (!png_ptr){
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "save_png(): Failed to initialize 'png_ptr' structure when saving file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_infop info_ptr = png_create_info_struct(png_ptr);
      if (!info_ptr) {
        png_destroy_write_struct(&png_ptr,(png_infopp)0);
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "save_png(): Failed to initialize 'info_ptr' structure when saving file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      if (setjmp(png_jmpbuf(png_ptr))) {
        png_destroy_write_struct(&png_ptr, &info_ptr);
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "save_png(): Encountered unknown fatal error in libpng when saving file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_init_io(png_ptr, nfile);

      const int bit_depth = bytes_per_pixel?(bytes_per_pixel*8):(stmax>=256?16:8);

      int color_type;
      switch (spectrum()) {
      case 1 : color_type = PNG_COLOR_TYPE_GRAY; break;
      case 2 : color_type = PNG_COLOR_TYPE_GRAY_ALPHA; break;
      case 3 : color_type = PNG_COLOR_TYPE_RGB; break;
      default : color_type = PNG_COLOR_TYPE_RGB_ALPHA;
      }
      const int interlace_type = PNG_INTERLACE_NONE;
      const int compression_type = PNG_COMPRESSION_TYPE_DEFAULT;
      const int filter_method = PNG_FILTER_TYPE_DEFAULT;
      png_set_IHDR(png_ptr,info_ptr,_width,_height,bit_depth,color_type,interlace_type,compression_type,filter_method);
      png_write_info(png_ptr,info_ptr);
      const int byte_depth = bit_depth>>3;
      const int numChan = spectrum()>4?4:spectrum();
      const int pixel_bit_depth_flag = numChan * (bit_depth - 1);

      // Allocate Memory for Image Save and Fill pixel data.
      png_bytep *const imgData = new png_byte*[_height];
      for (unsigned int row = 0; row<_height; ++row) imgData[row] = new png_byte[byte_depth*numChan*_width];
      const T *pC0 = data(0,0,0,0);
      switch (pixel_bit_depth_flag) {
      case 7 :  { // Gray 8-bit
        cimg_forY(*this,y) {
          unsigned char *ptrd = imgData[y];
          cimg_forX(*this,x) *(ptrd++) = (unsigned char)*(pC0++);
        }
      } break;
      case 14 : { // Gray w/ Alpha 8-bit
        const T *pC1 = data(0,0,0,1);
        cimg_forY(*this,y) {
          unsigned char *ptrd = imgData[y];
          cimg_forX(*this,x) {
            *(ptrd++) = (unsigned char)*(pC0++);
            *(ptrd++) = (unsigned char)*(pC1++);
          }
        }
      } break;
      case 21 :  { // RGB 8-bit
        const T *pC1 = data(0,0,0,1), *pC2 = data(0,0,0,2);
        cimg_forY(*this,y) {
          unsigned char *ptrd = imgData[y];
          cimg_forX(*this,x) {
            *(ptrd++) = (unsigned char)*(pC0++);
            *(ptrd++) = (unsigned char)*(pC1++);
            *(ptrd++) = (unsigned char)*(pC2++);
          }
        }
      } break;
      case 28 : { // RGB x/ Alpha 8-bit
        const T *pC1 = data(0,0,0,1), *pC2 = data(0,0,0,2), *pC3 = data(0,0,0,3);
        cimg_forY(*this,y){
          unsigned char *ptrd = imgData[y];
          cimg_forX(*this,x){
            *(ptrd++) = (unsigned char)*(pC0++);
            *(ptrd++) = (unsigned char)*(pC1++);
            *(ptrd++) = (unsigned char)*(pC2++);
            *(ptrd++) = (unsigned char)*(pC3++);
          }
        }
      } break;
      case 15 : { // Gray 16-bit
        cimg_forY(*this,y){
          unsigned short *ptrd = (unsigned short*)(imgData[y]);
          cimg_forX(*this,x) *(ptrd++) = (unsigned short)*(pC0++);
          if (!cimg::endianness()) cimg::invert_endianness((unsigned short*)imgData[y],_width);
        }
      } break;
      case 30 : { // Gray w/ Alpha 16-bit
        const T *pC1 = data(0,0,0,1);
        cimg_forY(*this,y){
          unsigned short *ptrd = (unsigned short*)(imgData[y]);
          cimg_forX(*this,x) {
            *(ptrd++) = (unsigned short)*(pC0++);
            *(ptrd++) = (unsigned short)*(pC1++);
          }
          if (!cimg::endianness()) cimg::invert_endianness((unsigned short*)imgData[y],2*_width);
        }
      } break;
      case 45 : { // RGB 16-bit
        const T *pC1 = data(0,0,0,1), *pC2 = data(0,0,0,2);
        cimg_forY(*this,y) {
          unsigned short *ptrd = (unsigned short*)(imgData[y]);
          cimg_forX(*this,x) {
            *(ptrd++) = (unsigned short)*(pC0++);
            *(ptrd++) = (unsigned short)*(pC1++);
            *(ptrd++) = (unsigned short)*(pC2++);
          }
          if (!cimg::endianness()) cimg::invert_endianness((unsigned short*)imgData[y],3*_width);
        }
      } break;
      case 60 : { // RGB w/ Alpha 16-bit
        const T *pC1 = data(0,0,0,1), *pC2 = data(0,0,0,2), *pC3 = data(0,0,0,3);
        cimg_forY(*this,y) {
          unsigned short *ptrd = (unsigned short*)(imgData[y]);
          cimg_forX(*this,x) {
            *(ptrd++) = (unsigned short)*(pC0++);
            *(ptrd++) = (unsigned short)*(pC1++);
            *(ptrd++) = (unsigned short)*(pC2++);
            *(ptrd++) = (unsigned short)*(pC3++);
          }
          if (!cimg::endianness()) cimg::invert_endianness((unsigned short*)imgData[y],4*_width);
        }
      } break;
      default :
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimg_instance
                              "save_png(): Encountered unknown fatal error in libpng when saving file '%s'.",
                              cimg_instance,
                              nfilename?nfilename:"(FILE*)");
      }
      png_write_image(png_ptr,imgData);
      png_write_end(png_ptr,info_ptr);
      png_destroy_write_struct(&png_ptr, &info_ptr);

      // Deallocate Image Write Memory.
      cimg_forY(*this,n) delete[] imgData[n];
      delete[] imgData;

      if (!file) cimg::fclose(nfile);
      return *this;
#endif
    }

    //! Save the image as a PNM file.
    /**
      \param filename Filename, as a C-string.
      \param bytes_per_pixel Force the number of bytes per pixels for the saving.
    **/
    const CImg<T>& save_pnm(const char *const filename, const unsigned int bytes_per_pixel=0) const {
      return _save_pnm(0,filename,bytes_per_pixel);
    }

    //! Save the image as a PNM file \overload.
    const CImg<T>& save_pnm(std::FILE *const file, const unsigned int bytes_per_pixel=0) const {
      return _save_pnm(file,0,bytes_per_pixel);
    }

    const CImg<T>& _save_pnm(std::FILE *const file, const char *const filename,
                             const unsigned int bytes_per_pixel=0) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_pnm(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }

      double stmin, stmax = (double)max_min(stmin);
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_pnm(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (_spectrum>3)
        cimg::warn(_cimg_instance
                   "save_pnm(): Instance is multispectral, only the three first channels will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (stmin<0 || (bytes_per_pixel==1 && stmax>=256) || stmax>=65536)
        cimg::warn(_cimg_instance
                   "save_pnm(): Instance has pixel values in [%g,%g], probable type overflow in file '%s'.",
                   cimg_instance,
                   stmin,stmax,filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const T
        *ptr_r = data(0,0,0,0),
        *ptr_g = (_spectrum>=2)?data(0,0,0,1):0,
        *ptr_b = (_spectrum>=3)?data(0,0,0,2):0;
      const ulongT buf_size = std::min((ulongT)(1024*1024),(ulongT)(_width*_height*(_spectrum==1?1UL:3UL)));

      std::fprintf(nfile,"P%c\n%u %u\n%u\n",
                   (_spectrum==1?'5':'6'),_width,_height,stmax<256?255:(stmax<4096?4095:65535));

      switch (_spectrum) {
      case 1 : { // Scalar image
        if (bytes_per_pixel==1 || (!bytes_per_pixel && stmax<256)) { // Binary PGM 8 bits
          CImg<ucharT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size);
            unsigned char *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) *(ptrd++) = (unsigned char)*(ptr_r++);
            cimg::fwrite(buf._data,N,nfile);
            to_write-=N;
          }
        } else { // Binary PGM 16 bits
          CImg<ushortT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size);
            unsigned short *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) *(ptrd++) = (unsigned short)*(ptr_r++);
            if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
            cimg::fwrite(buf._data,N,nfile);
            to_write-=N;
          }
        }
      } break;
      case 2 : { // RG image
        if (bytes_per_pixel==1 || (!bytes_per_pixel && stmax<256)) { // Binary PPM 8 bits
          CImg<ucharT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size/3);
            unsigned char *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) {
              *(ptrd++) = (unsigned char)*(ptr_r++);
              *(ptrd++) = (unsigned char)*(ptr_g++);
              *(ptrd++) = 0;
            }
            cimg::fwrite(buf._data,3*N,nfile);
            to_write-=N;
          }
        } else { // Binary PPM 16 bits
          CImg<ushortT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size/3);
            unsigned short *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) {
              *(ptrd++) = (unsigned short)*(ptr_r++);
              *(ptrd++) = (unsigned short)*(ptr_g++);
              *(ptrd++) = 0;
            }
            if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
            cimg::fwrite(buf._data,3*N,nfile);
            to_write-=N;
          }
        }
      } break;
      default : { // RGB image
        if (bytes_per_pixel==1 || (!bytes_per_pixel && stmax<256)) { // Binary PPM 8 bits
          CImg<ucharT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size/3);
            unsigned char *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) {
              *(ptrd++) = (unsigned char)*(ptr_r++);
              *(ptrd++) = (unsigned char)*(ptr_g++);
              *(ptrd++) = (unsigned char)*(ptr_b++);
            }
            cimg::fwrite(buf._data,3*N,nfile);
            to_write-=N;
          }
        } else { // Binary PPM 16 bits
          CImg<ushortT> buf((unsigned int)buf_size);
          for (longT to_write = (longT)width()*height(); to_write>0; ) {
            const ulongT N = std::min((ulongT)to_write,buf_size/3);
            unsigned short *ptrd = buf._data;
            for (ulongT i = N; i>0; --i) {
              *(ptrd++) = (unsigned short)*(ptr_r++);
              *(ptrd++) = (unsigned short)*(ptr_g++);
              *(ptrd++) = (unsigned short)*(ptr_b++);
            }
            if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
            cimg::fwrite(buf._data,3*N,nfile);
            to_write-=N;
          }
        }
      }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a PNK file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_pnk(const char *const filename) const {
      return _save_pnk(0,filename);
    }

    //! Save the image as a PNK file \overload.
    const CImg<T>& save_pnk(std::FILE *const file) const {
      return _save_pnk(file,0);
    }

    const CImg<T>& _save_pnk(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_pnk(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_spectrum>1)
        cimg::warn(_cimg_instance
                   "save_pnk(): Instance is multispectral, only the first channel will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      const ulongT buf_size = std::min((ulongT)1024*1024,(ulongT)_width*_height*_depth);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const T *ptr = data(0,0,0,0);

      if (!cimg::type<T>::is_float() && sizeof(T)==1 && _depth<2) // Can be saved as regular PNM file
        _save_pnm(file,filename,0);
      else if (!cimg::type<T>::is_float() && sizeof(T)==1) { // Save as extended P5 file: Binary byte-valued 3D
        std::fprintf(nfile,"P5\n%u %u %u\n255\n",_width,_height,_depth);
        CImg<ucharT> buf((unsigned int)buf_size);
        for (longT to_write = (longT)width()*height()*depth(); to_write>0; ) {
          const ulongT N = std::min((ulongT)to_write,buf_size);
          unsigned char *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) *(ptrd++) = (unsigned char)*(ptr++);
          cimg::fwrite(buf._data,N,nfile);
          to_write-=N;
        }
      } else if (!cimg::type<T>::is_float()) { // Save as P8: Binary int32-valued 3D
        if (_depth>1) std::fprintf(nfile,"P8\n%u %u %u\n%d\n",_width,_height,_depth,(int)max());
        else std::fprintf(nfile,"P8\n%u %u\n%d\n",_width,_height,(int)max());
        CImg<intT> buf((unsigned int)buf_size);
        for (longT to_write = (longT)width()*height()*depth(); to_write>0; ) {
          const ulongT N = std::min((ulongT)to_write,buf_size);
          int *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) *(ptrd++) = (int)*(ptr++);
          cimg::fwrite(buf._data,N,nfile);
          to_write-=N;
        }
      } else { // Save as P9: Binary float-valued 3D
        if (_depth>1) std::fprintf(nfile,"P9\n%u %u %u\n%g\n",_width,_height,_depth,(double)max());
        else std::fprintf(nfile,"P9\n%u %u\n%g\n",_width,_height,(double)max());
        CImg<floatT> buf((unsigned int)buf_size);
        for (longT to_write = (longT)width()*height()*depth(); to_write>0; ) {
          const ulongT N = std::min((ulongT)to_write,buf_size);
          float *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) *(ptrd++) = (float)*(ptr++);
          cimg::fwrite(buf._data,N,nfile);
          to_write-=N;
        }
      }

      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a PFM file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_pfm(const char *const filename) const {
      get_mirror('y')._save_pfm(0,filename);
      return *this;
    }

    //! Save the image as a PFM file \overload.
    const CImg<T>& save_pfm(std::FILE *const file) const {
      get_mirror('y')._save_pfm(file,0);
      return *this;
    }

    const CImg<T>& _save_pfm(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_pfm(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_pfm(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (_spectrum>3)
        cimg::warn(_cimg_instance
                   "save_pfm(): image instance is multispectral, only the three first channels will be saved "
                   "in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const T
        *ptr_r = data(0,0,0,0),
        *ptr_g = (_spectrum>=2)?data(0,0,0,1):0,
        *ptr_b = (_spectrum>=3)?data(0,0,0,2):0;
      const unsigned int buf_size = std::min(1024*1024U,_width*_height*(_spectrum==1?1:3));

      std::fprintf(nfile,"P%c\n%u %u\n1.0\n",
                   (_spectrum==1?'f':'F'),_width,_height);

      switch (_spectrum) {
      case 1 : { // Scalar image
        CImg<floatT> buf(buf_size);
        for (longT to_write = (longT)width()*height(); to_write>0; ) {
          const ulongT N = std::min((ulongT)to_write,(ulongT)buf_size);
          float *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) *(ptrd++) = (float)*(ptr_r++);
          if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
          cimg::fwrite(buf._data,N,nfile);
          to_write-=N;
        }
      } break;
      case 2 : { // RG image
        CImg<floatT> buf(buf_size);
        for (longT to_write = (longT)width()*height(); to_write>0; ) {
          const unsigned int N = std::min((unsigned int)to_write,buf_size/3);
          float *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) {
            *(ptrd++) = (float)*(ptr_r++);
            *(ptrd++) = (float)*(ptr_g++);
            *(ptrd++) = 0;
          }
          if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
          cimg::fwrite(buf._data,3*N,nfile);
          to_write-=N;
        }
      } break;
      default : { // RGB image
        CImg<floatT> buf(buf_size);
        for (longT to_write = (longT)width()*height(); to_write>0; ) {
          const unsigned int N = std::min((unsigned int)to_write,buf_size/3);
          float *ptrd = buf._data;
          for (ulongT i = N; i>0; --i) {
            *(ptrd++) = (float)*(ptr_r++);
            *(ptrd++) = (float)*(ptr_g++);
            *(ptrd++) = (float)*(ptr_b++);
          }
          if (!cimg::endianness()) cimg::invert_endianness(buf._data,buf_size);
          cimg::fwrite(buf._data,3*N,nfile);
          to_write-=N;
        }
      }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a RGB file.
    /**
      \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_rgb(const char *const filename) const {
      return _save_rgb(0,filename);
    }

    //! Save the image as a RGB file \overload.
    const CImg<T>& save_rgb(std::FILE *const file) const {
      return _save_rgb(file,0);
    }

    const CImg<T>& _save_rgb(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_rgb(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_spectrum!=3)
        cimg::warn(_cimg_instance
                   "save_rgb(): image instance has not exactly 3 channels, for file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const ulongT wh = (ulongT)_width*_height;
      CImg<ucharT> _buffer(3*wh);
      unsigned char *const buffer = _buffer._data, *nbuffer = buffer;
      const T
        *ptr1 = data(0,0,0,0),
        *ptr2 = _spectrum>1?data(0,0,0,1):0,
        *ptr3 = _spectrum>2?data(0,0,0,2):0;
      switch (_spectrum) {
      case 1 : { // Scalar image
        for (ulongT k = 0; k<wh; ++k) {
          const unsigned char val = (unsigned char)*(ptr1++);
          *(nbuffer++) = val;
          *(nbuffer++) = val;
          *(nbuffer++) = val;
        }
      } break;
      case 2 : { // RG image
        for (ulongT k = 0; k<wh; ++k) {
          *(nbuffer++) = (unsigned char)(*(ptr1++));
          *(nbuffer++) = (unsigned char)(*(ptr2++));
          *(nbuffer++) = 0;
        }
      } break;
      default : { // RGB image
        for (ulongT k = 0; k<wh; ++k) {
          *(nbuffer++) = (unsigned char)(*(ptr1++));
          *(nbuffer++) = (unsigned char)(*(ptr2++));
          *(nbuffer++) = (unsigned char)(*(ptr3++));
        }
      }
      }
      cimg::fwrite(buffer,3*wh,nfile);
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a RGBA file.
    /**
       \param filename Filename, as a C-string.
    **/
    const CImg<T>& save_rgba(const char *const filename) const {
      return _save_rgba(0,filename);
    }

    //! Save the image as a RGBA file \overload.
    const CImg<T>& save_rgba(std::FILE *const file) const {
      return _save_rgba(file,0);
    }

    const CImg<T>& _save_rgba(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_rgba(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_spectrum!=4)
        cimg::warn(_cimg_instance
                   "save_rgba(): image instance has not exactly 4 channels, for file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const ulongT wh = (ulongT)_width*_height;
      CImg<ucharT> _buffer(4*wh);
      unsigned char *const buffer = _buffer._data, *nbuffer = buffer;
      const T
        *ptr1 = data(0,0,0,0),
        *ptr2 = _spectrum>1?data(0,0,0,1):0,
        *ptr3 = _spectrum>2?data(0,0,0,2):0,
        *ptr4 = _spectrum>3?data(0,0,0,3):0;
      switch (_spectrum) {
      case 1 : { // Scalar images
        for (ulongT k = 0; k<wh; ++k) {
          const unsigned char val = (unsigned char)*(ptr1++);
          *(nbuffer++) = val;
          *(nbuffer++) = val;
          *(nbuffer++) = val;
          *(nbuffer++) = 255;
        }
      } break;
      case 2 : { // RG images
        for (ulongT k = 0; k<wh; ++k) {
          *(nbuffer++) = (unsigned char)(*(ptr1++));
          *(nbuffer++) = (unsigned char)(*(ptr2++));
          *(nbuffer++) = 0;
          *(nbuffer++) = 255;
        }
      } break;
      case 3 : { // RGB images
        for (ulongT k = 0; k<wh; ++k) {
          *(nbuffer++) = (unsigned char)(*(ptr1++));
          *(nbuffer++) = (unsigned char)(*(ptr2++));
          *(nbuffer++) = (unsigned char)(*(ptr3++));
          *(nbuffer++) = 255;
        }
      } break;
      default : { // RGBA images
        for (ulongT k = 0; k<wh; ++k) {
          *(nbuffer++) = (unsigned char)(*(ptr1++));
          *(nbuffer++) = (unsigned char)(*(ptr2++));
          *(nbuffer++) = (unsigned char)(*(ptr3++));
          *(nbuffer++) = (unsigned char)(*(ptr4++));
        }
      }
      }
      cimg::fwrite(buffer,4*wh,nfile);
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a TIFF file.
    /**
       \param filename Filename, as a C-string.
       \param compression_type Type of data compression. Can be
        <tt>{ 0=None | 1=ADOBE_DEFLATE | 2=CCITT_T4 | 3=CCITT_T6 | 4=CCITTFAX3 | 5=CCITTFAX4 | 6=CCITTRLE |
          7=CCITTRLEW | 8=DCS | 9=DEFLATE | 10=IT8BL | 11=IT8CTPAD | 12=IT8LW | 13=IT8MP | 14=JBIG |
          15=JP2000 | 16=JPEG | 17=JXL | 18=LERC | 19=LZMA | 20=LZW | 21=NEXT | 22=OJPEG | 23=PACKBITS |
          24=PIXARFILM | 25=PIXARLOG | 26=SGILOG | 27=SGILOG24 | 28=T43 | 29=T85 | 30=THUNDERSCAN |
          31=WEBP | 32=ZSTD }</tt>
       \param[out] voxel_size Voxel size, to be stored in the file metadata.
       \param[out] description Description, to be stored in the file metadata.
       \param use_bigtiff Indicates whether the file is saved as BigTIFF (>4 GB) or not.
       \note
       - libtiff support is enabled by defining the precompilation
        directive \c cimg_use_tiff.
       - When libtiff is enabled, 2D and 3D (multipage) several channels per pixel are supported for
        <tt>char,uchar,short,ushort,float</tt> and \c double pixel types.
       - If \c cimg_use_tiff is not defined at compile time the
        function uses CImg<T>&save_other(const char*).
     **/
    const CImg<T>& save_tiff(const char *const filename, const unsigned int compression_type=0,
                             const float *const voxel_size=0, const char *const description=0,
                             const bool use_bigtiff=true) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_tiff(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

#ifdef cimg_use_tiff
      const bool
        _use_bigtiff = use_bigtiff && sizeof(ulongT)>=8 && size()*sizeof(T)>=1UL<<31; // No bigtiff for small images
      TIFF *tif = TIFFOpen(filename,_use_bigtiff?"w8":"w4");
      if (tif) {
        double val_min, val_max = (double)max_min(val_min);
        cimg_forZ(*this,z) _save_tiff(tif,z,z,compression_type,voxel_size,description,val_min,val_max);
        TIFFClose(tif);
      } else throw CImgIOException(_cimg_instance
                                   "save_tiff(): Failed to open file '%s' for writing.",
                                   cimg_instance,
                                   filename);
      return *this;
#else
      cimg::unused(compression_type,voxel_size,description,use_bigtiff);
      return save_other(filename);
#endif
    }

#ifdef cimg_use_tiff

#define _cimg_save_tiff(types,typed) if (!std::strcmp(types,pixel_type())) { \
    const typed foo = (typed)0; return _save_tiff(tif,directory,z,foo,compression_type,voxel_size,description,\
                                                  val_min,val_max); }

    // [internal] Save a plane into a tiff file.
    template<typename t>
    const CImg<T>& _save_tiff(TIFF *tif, const unsigned int directory, const unsigned int z, const t& pixel_t,
                              const unsigned int compression_type, const float *const voxel_size,
                              const char *const description, double val_min, double val_max) const {
      if (is_empty() || !tif || pixel_t) return *this;
      const unsigned int compression_codes[] = {
        COMPRESSION_NONE, COMPRESSION_ADOBE_DEFLATE, COMPRESSION_CCITT_T4, COMPRESSION_CCITT_T6,
        COMPRESSION_CCITTFAX3, COMPRESSION_CCITTFAX4, COMPRESSION_CCITTRLE, COMPRESSION_CCITTRLEW,
        COMPRESSION_DCS, COMPRESSION_DEFLATE, COMPRESSION_IT8BL, COMPRESSION_IT8CTPAD, COMPRESSION_IT8LW,
        COMPRESSION_IT8MP, COMPRESSION_JBIG, COMPRESSION_JP2000, COMPRESSION_JPEG,
#ifdef COMPRESSION_JXL
        COMPRESSION_JXL,
#else
        COMPRESSION_NONE,
#endif
        COMPRESSION_LERC, COMPRESSION_LZMA, COMPRESSION_LZW, COMPRESSION_NEXT, COMPRESSION_OJPEG,
        COMPRESSION_PACKBITS, COMPRESSION_PIXARFILM, COMPRESSION_PIXARLOG, COMPRESSION_SGILOG,
        COMPRESSION_SGILOG24, COMPRESSION_T43, COMPRESSION_T85, COMPRESSION_THUNDERSCAN, COMPRESSION_WEBP,
        COMPRESSION_ZSTD },
        nb_compression_codes = sizeof(compression_codes)/sizeof(unsigned int);
      if (compression_type>=nb_compression_codes)
        throw CImgArgumentException(_cimg_instance
                                    "save_tiff(): Specified compression type (%u) is invalid "
                                    "(should be in range [0,%u]).",
                                    cimg_instance,nb_compression_codes - 1);
      const unsigned int compression_code = compression_codes[compression_type];
      const char *const filename = TIFFFileName(tif);
      cimg_uint32 rowsperstrip = (cimg_uint32)-1;
      cimg_uint16 spp = _spectrum, bpp = sizeof(t)*8, photometric;
      if (spp==3 || spp==4) photometric = PHOTOMETRIC_RGB;
      else photometric = PHOTOMETRIC_MINISBLACK;
      TIFFSetDirectory(tif,directory);
      TIFFSetField(tif,TIFFTAG_IMAGEWIDTH,_width);
      TIFFSetField(tif,TIFFTAG_IMAGELENGTH,_height);
      if (voxel_size) {
        const float vx = voxel_size[0], vy = voxel_size[1], vz = voxel_size[2];
        TIFFSetField(tif,TIFFTAG_RESOLUTIONUNIT,RESUNIT_NONE);
        TIFFSetField(tif,TIFFTAG_XRESOLUTION,1.f/vx);
        TIFFSetField(tif,TIFFTAG_YRESOLUTION,1.f/vy);
        CImg<charT> s_description(256);
        cimg_snprintf(s_description,s_description._width,"VX=%g VY=%g VZ=%g spacing=%g",vx,vy,vz,vz);
        TIFFSetField(tif,TIFFTAG_IMAGEDESCRIPTION,s_description.data());
      }
      if (description) TIFFSetField(tif,TIFFTAG_IMAGEDESCRIPTION,description);
      TIFFSetField(tif,TIFFTAG_ORIENTATION,ORIENTATION_TOPLEFT);
      TIFFSetField(tif,TIFFTAG_SAMPLESPERPIXEL,spp);
      if (cimg::type<t>::is_float()) TIFFSetField(tif,TIFFTAG_SAMPLEFORMAT,3);
      else if (cimg::type<t>::min()==0) TIFFSetField(tif,TIFFTAG_SAMPLEFORMAT,1);
      else TIFFSetField(tif,TIFFTAG_SAMPLEFORMAT,2);
      TIFFSetField(tif,TIFFTAG_SMINSAMPLEVALUE,val_min);
      TIFFSetField(tif,TIFFTAG_SMAXSAMPLEVALUE,val_max);
      TIFFSetField(tif,TIFFTAG_BITSPERSAMPLE,bpp);
      TIFFSetField(tif,TIFFTAG_PLANARCONFIG,PLANARCONFIG_CONTIG);
      TIFFSetField(tif,TIFFTAG_PHOTOMETRIC,photometric);
      TIFFSetField(tif,TIFFTAG_COMPRESSION,compression_code);
      rowsperstrip = TIFFDefaultStripSize(tif,rowsperstrip);
      TIFFSetField(tif,TIFFTAG_ROWSPERSTRIP,rowsperstrip);
      TIFFSetField(tif,TIFFTAG_FILLORDER,FILLORDER_MSB2LSB);
      TIFFSetField(tif,TIFFTAG_SOFTWARE,cimg_appname);

      t *const buf = (t*)_TIFFmalloc(TIFFStripSize(tif));
      if (buf) {
        for (unsigned int row = 0; row<_height; row+=rowsperstrip) {
          cimg_uint32 nrow = (row + rowsperstrip>_height?_height - row:rowsperstrip);
          tstrip_t strip = TIFFComputeStrip(tif,row,0);
          tsize_t i = 0;
          for (unsigned int rr = 0; rr<nrow; ++rr)
            for (unsigned int cc = 0; cc<_width; ++cc)
              for (unsigned int vv = 0; vv<spp; ++vv)
                buf[i++] = (t)(*this)(cc,row + rr,z,vv);
          if (TIFFWriteEncodedStrip(tif,strip,buf,i*sizeof(t))<0) {
            _TIFFfree(buf);
            throw CImgIOException(_cimg_instance
                                  "save_tiff(): Invalid strip writing when saving file '%s'.",
                                  cimg_instance,
                                  filename?filename:"(FILE*)");
          }
        }
        _TIFFfree(buf);
      }
      TIFFWriteDirectory(tif);
      return *this;
    }

    const CImg<T>& _save_tiff(TIFF *tif, const unsigned int directory, const unsigned int z,
                              const unsigned int compression_type, const float *const voxel_size,
                              const char *const description, double val_min, double val_max) const {
      _cimg_save_tiff("uint8",cimg_uint8);
      _cimg_save_tiff("int8",cimg_int8);
      _cimg_save_tiff("uint16",cimg_uint16);
      _cimg_save_tiff("int16",cimg_int16);
      _cimg_save_tiff("uint32",cimg_uint32);
      _cimg_save_tiff("int32",cimg_int32);
      _cimg_save_tiff("uint64",cimg_uint32); // 'int64' as 'int32'
      _cimg_save_tiff("int64",cimg_int32);
      _cimg_save_tiff("float16",cimg_float32); // 'float16' as 'float32'
      _cimg_save_tiff("float32",cimg_float32);
      _cimg_save_tiff("float64",cimg_float32); // 'float64' as 'float32'
      const char *const filename = TIFFFileName(tif);
      throw CImgInstanceException(_cimg_instance
                                  "save_tiff(): Unsupported pixel type '%s' for file '%s'.",
                                  cimg_instance,
                                  pixel_type(),filename?filename:"(FILE*)");
      return *this;
    }
#endif

    //! Save the image as a MINC2 file.
    /**
       \param filename Filename, as a C-string.
       \param imitate_file If non-zero, reference filename, as a C-string, to borrow header from.
    **/
    const CImg<T>& save_minc2(const char *const filename,
                              const char *const imitate_file=0) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                   "save_minc2(): Specified filename is (null).",
                                   cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

#ifndef cimg_use_minc2
     cimg::unused(imitate_file);
     return save_other(filename);
#else
     minc::minc_1_writer wtr;
     if (imitate_file)
       wtr.open(filename, imitate_file);
     else {
       minc::minc_info di;
       if (width()) di.push_back(minc::dim_info(width(),width()*0.5,-1,minc::dim_info::DIM_X));
       if (height()) di.push_back(minc::dim_info(height(),height()*0.5,-1,minc::dim_info::DIM_Y));
       if (depth()) di.push_back(minc::dim_info(depth(),depth()*0.5,-1,minc::dim_info::DIM_Z));
       if (spectrum()) di.push_back(minc::dim_info(spectrum(),spectrum()*0.5,-1,minc::dim_info::DIM_TIME));
       wtr.open(filename,di,1,NC_FLOAT,0);
     }
     if (pixel_type()==cimg::type<unsigned char>::string())
       wtr.setup_write_byte();
     else if (pixel_type()==cimg::type<int>::string())
       wtr.setup_write_int();
     else if (pixel_type()==cimg::type<double>::string())
       wtr.setup_write_double();
     else
       wtr.setup_write_float();
     minc::save_standard_volume(wtr, this->_data);
     return *this;
#endif
    }

    //! Save the image as an ANALYZE7.5 or NIFTI file.
    /**
      \param filename Filename, as a C-string.
      \param voxel_size Pointer to 3 consecutive values that tell about the voxel sizes along the X,Y and Z dimensions.
    **/
    const CImg<T>& save_analyze(const char *const filename, const float *const voxel_size=0) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_analyze(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

      std::FILE *file;
      CImg<charT> hname(1024), iname(1024);
      const char *const ext = cimg::split_filename(filename);
      short datatype = -1;
      if (!*ext) {
        cimg_snprintf(hname,hname._width,"%s.hdr",filename);
        cimg_snprintf(iname,iname._width,"%s.img",filename);
      }
      if (!cimg::strncasecmp(ext,"hdr",3)) {
        std::strcpy(hname,filename);
        std::strncpy(iname,filename,iname._width - 1);
        cimg_snprintf(iname._data + std::strlen(iname) - 3,4,"img");
      }
      if (!cimg::strncasecmp(ext,"img",3)) {
        std::strcpy(hname,filename);
        std::strncpy(iname,filename,iname._width - 1);
        cimg_snprintf(hname._data + std::strlen(iname) - 3,4,"hdr");
      }
      if (!cimg::strncasecmp(ext,"nii",3)) {
        std::strncpy(hname,filename,hname._width - 1); *iname = 0;
      }

      CImg<charT> header(*iname?348:352,1,1,1,0);
      int *const iheader = (int*)header._data;
      *iheader = 348;
      std::strcpy(header._data + 4,"CImg");
      std::strcpy(header._data + 14," ");
      ((short*)&(header[36]))[0] = 4096;
      ((char*)&(header[38]))[0] = 114;
      ((short*)&(header[40]))[0] = 4;
      ((short*)&(header[40]))[1] = (short)_width;
      ((short*)&(header[40]))[2] = (short)_height;
      ((short*)&(header[40]))[3] = (short)_depth;
      ((short*)&(header[40]))[4] = (short)_spectrum;
      if (!cimg::strcasecmp(pixel_type(),"bool") ||
          !cimg::strcasecmp(pixel_type(),"uint8") ||
          !cimg::strcasecmp(pixel_type(),"int8")) datatype = 2;
      if (!cimg::strcasecmp(pixel_type(),"uint16") ||
          !cimg::strcasecmp(pixel_type(),"int16")) datatype = 4;
      if (!cimg::strcasecmp(pixel_type(),"uint32") ||
          !cimg::strcasecmp(pixel_type(),"int32")) datatype = 8;
      if (!cimg::strcasecmp(pixel_type(),"uint64") ||
          !cimg::strcasecmp(pixel_type(),"int64")) datatype = 8;
      if (!cimg::strcasecmp(pixel_type(),"float32")) datatype = 16;
      if (!cimg::strcasecmp(pixel_type(),"float64")) datatype = 64;
      if (datatype<0)
        throw CImgIOException(_cimg_instance
                              "save_analyze(): Unsupported pixel type '%s' for file '%s'.",
                              cimg_instance,
                              pixel_type(),filename);

      ((short*)&(header[70]))[0] = datatype;
      ((short*)&(header[72]))[0] = sizeof(T);
      ((float*)&(header[108]))[0] = (float)(*iname?0:header.width());
      ((float*)&(header[112]))[0] = 1;
      ((float*)&(header[76]))[0] = 0;
      if (voxel_size) {
        ((float*)&(header[76]))[1] = voxel_size[0];
        ((float*)&(header[76]))[2] = voxel_size[1];
        ((float*)&(header[76]))[3] = voxel_size[2];
      } else ((float*)&(header[76]))[1] = ((float*)&(header[76]))[2] = ((float*)&(header[76]))[3] = 1;
      file = cimg::fopen(hname,"wb");
      cimg::fwrite(header._data,header.width(),file);
      if (*iname) { cimg::fclose(file); file = cimg::fopen(iname,"wb"); }
      cimg::fwrite(_data,size(),file);
      cimg::fclose(file);
      return *this;
    }

    //! Save the image as a .cimg file.
    /**
      \param filename Filename, as a C-string.
      \param is_compressed Indicates whether the file contains compressed image data.
    **/
    const CImg<T>& save_cimg(const char *const filename, const bool is_compressed=false) const {
      CImgList<T>(*this,true).save_cimg(filename,is_compressed);
      return *this;
    }

    //! Save the image as a .cimg file \overload.
    const CImg<T>& save_cimg(std::FILE *const file, const bool is_compressed=false) const {
      CImgList<T>(*this,true).save_cimg(file,is_compressed);
      return *this;
    }

    //! Save the image as a sub-image into an existing .cimg file.
    /**
      \param filename Filename, as a C-string.
      \param n0 Index of the image inside the file.
      \param x0 X-coordinate of the sub-image location.
      \param y0 Y-coordinate of the sub-image location.
      \param z0 Z-coordinate of the sub-image location.
      \param c0 C-coordinate of the sub-image location.
    **/
    const CImg<T>& save_cimg(const char *const filename,
                             const unsigned int n0,
                             const unsigned int x0, const unsigned int y0,
                             const unsigned int z0, const unsigned int c0) const {
      CImgList<T>(*this,true).save_cimg(filename,n0,x0,y0,z0,c0);
      return *this;
    }

    //! Save the image as a sub-image into an existing .cimg file \overload.
    const CImg<T>& save_cimg(std::FILE *const file,
                             const unsigned int n0,
                             const unsigned int x0, const unsigned int y0,
                             const unsigned int z0, const unsigned int c0) const {
      CImgList<T>(*this,true).save_cimg(file,n0,x0,y0,z0,c0);
      return *this;
    }

    //! Save a blank image as a .cimg file.
    /**
        \param filename Filename, as a C-string.
        \param dx Width of the image.
        \param dy Height of the image.
        \param dz Depth of the image.
        \param dc Number of channels of the image.
        \note
        - All pixel values of the saved image are set to \c 0.
        - Use this function to save large images without having to instantiate and allocate them.
    **/
    static void save_empty_cimg(const char *const filename,
                                const unsigned int dx, const unsigned int dy=1,
                                const unsigned int dz=1, const unsigned int dc=1) {
      return CImgList<T>::save_empty_cimg(filename,1,dx,dy,dz,dc);
    }

    //! Save a blank image as a .cimg file \overload.
    /**
       Same as save_empty_cimg(const char *,unsigned int,unsigned int,unsigned int,unsigned int)
       with a file stream argument instead of a filename string.
    **/
    static void save_empty_cimg(std::FILE *const file,
                                const unsigned int dx, const unsigned int dy=1,
                                const unsigned int dz=1, const unsigned int dc=1) {
      return CImgList<T>::save_empty_cimg(file,1,dx,dy,dz,dc);
    }

    //! Save the image as an INRIMAGE-4 file.
    /**
      \param filename Filename, as a C-string.
      \param voxel_size Pointer to 3 values specifying the voxel sizes along the X,Y and Z dimensions.
    **/
    const CImg<T>& save_inr(const char *const filename, const float *const voxel_size=0) const {
      return _save_inr(0,filename,voxel_size);
    }

    //! Save the image as an INRIMAGE-4 file \overload.
    const CImg<T>& save_inr(std::FILE *const file, const float *const voxel_size=0) const {
      return _save_inr(file,0,voxel_size);
    }

    const CImg<T>& _save_inr(std::FILE *const file, const char *const filename, const float *const voxel_size) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_inr(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }

      int inrpixsize = -1;
      const char *inrtype = "unsigned fixed\nPIXSIZE=8 bits\nSCALE=2**0";
      if (!cimg::strcasecmp(pixel_type(),"uint8")) {
        inrtype = "unsigned fixed\nPIXSIZE=8 bits\nSCALE=2**0"; inrpixsize = 1;
      }
      if (!cimg::strcasecmp(pixel_type(),"int8")) {
        inrtype = "fixed\nPIXSIZE=8 bits\nSCALE=2**0"; inrpixsize = 1;
      }
      if (!cimg::strcasecmp(pixel_type(),"uint16")) {
        inrtype = "unsigned fixed\nPIXSIZE=16 bits\nSCALE=2**0";inrpixsize = 2;
      }
      if (!cimg::strcasecmp(pixel_type(),"int16")) {
        inrtype = "fixed\nPIXSIZE=16 bits\nSCALE=2**0"; inrpixsize = 2;
      }
      if (!cimg::strcasecmp(pixel_type(),"uint32")) {
        inrtype = "unsigned fixed\nPIXSIZE=32 bits\nSCALE=2**0";inrpixsize = 4;
      }
      if (!cimg::strcasecmp(pixel_type(),"int32")) {
        inrtype = "fixed\nPIXSIZE=32 bits\nSCALE=2**0"; inrpixsize = 4;
      }
      if (!cimg::strcasecmp(pixel_type(),"float32")) {
        inrtype = "float\nPIXSIZE=32 bits"; inrpixsize = 4;
      }
      if (!cimg::strcasecmp(pixel_type(),"float64")) {
        inrtype = "float\nPIXSIZE=64 bits"; inrpixsize = 8;
      }
      if (inrpixsize<=0)
        throw CImgIOException(_cimg_instance
                              "save_inr(): Unsupported pixel type '%s' for file '%s'",
                              cimg_instance,
                              pixel_type(),filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      CImg<charT> header(257);
      int err = cimg_snprintf(header,header._width,"#INRIMAGE-4#{\nXDIM=%u\nYDIM=%u\nZDIM=%u\nVDIM=%u\n",
                              _width,_height,_depth,_spectrum);
      if (voxel_size)
        err+=cimg_snprintf(header._data + err,128,"VX=%g\nVY=%g\nVZ=%g\n",
                          voxel_size[0],voxel_size[1],voxel_size[2]);
      err+=cimg_snprintf(header._data + err,128,"TYPE=%s\nCPU=%s\n",
                         inrtype,cimg::endianness()?"sun":"decm");
      std::memset(header._data + err,'\n',252 - err);
      std::memcpy(header._data + 252,"##}\n",4);
      cimg::fwrite(header._data,256,nfile);
      cimg_forXYZ(*this,x,y,z) cimg_forC(*this,c) cimg::fwrite(&((*this)(x,y,z,c)),1,nfile);
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as an OpenEXR file.
    /**
       \param filename Filename, as a C-string.
       \note The OpenEXR file format is <a href="http://en.wikipedia.org/wiki/OpenEXR">described here</a>.
    **/
    const CImg<T>& save_exr(const char *const filename) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_exr(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_exr(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename);

#ifndef cimg_use_openexr
      return save_other(filename);
#else
      Imf::Rgba *const ptrd0 = new Imf::Rgba[(size_t)_width*_height], *ptrd = ptrd0, rgba;
      switch (_spectrum) {
      case 1 : { // Grayscale image
        for (const T *ptr_r = data(), *const ptr_e = ptr_r + (ulongT)_width*_height; ptr_r<ptr_e;) {
          rgba.r = (cimg_float16)(*(ptr_r));
          rgba.g = (cimg_float16)(*(ptr_r));
          rgba.b = (cimg_float16)(*(ptr_r++));
          rgba.a = (cimg_float16)1;
          *(ptrd++) = rgba;
        }
      } break;
      case 2 : { // RG image
        for (const T *ptr_r = data(), *ptr_g = data(0,0,0,1),
               *const ptr_e = ptr_r + (ulongT)_width*_height; ptr_r<ptr_e; ) {
          rgba.r = (cimg_float16)(*(ptr_r++));
          rgba.g = (cimg_float16)(*(ptr_g++));
          rgba.b = (cimg_float16)0;
          rgba.a = (cimg_float16)1;
          *(ptrd++) = rgba;
        }
      } break;
      case 3 : { // RGB image
        for (const T *ptr_r = data(), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2),
               *const ptr_e = ptr_r + (ulongT)_width*_height; ptr_r<ptr_e;) {
          rgba.r = (cimg_float16)(*(ptr_r++));
          rgba.g = (cimg_float16)(*(ptr_g++));
          rgba.b = (cimg_float16)(*(ptr_b++));
          rgba.a = (cimg_float16)1;
          *(ptrd++) = rgba;
        }
      } break;
      default : { // RGBA image
        for (const T *ptr_r = data(), *ptr_g = data(0,0,0,1), *ptr_b = data(0,0,0,2), *ptr_a = data(0,0,0,3),
               *const ptr_e = ptr_r + (ulongT)_width*_height; ptr_r<ptr_e;) {
          rgba.r = (cimg_float16)(*(ptr_r++));
          rgba.g = (cimg_float16)(*(ptr_g++));
          rgba.b = (cimg_float16)(*(ptr_b++));
          rgba.a = (cimg_float16)(*(ptr_a++));
          *(ptrd++) = rgba;
        }
      } break;
      }
      Imf::RgbaOutputFile outFile(filename,_width,_height,
                                  _spectrum==1?Imf::WRITE_Y:_spectrum==2?Imf::WRITE_YA:_spectrum==3?
                                  Imf::WRITE_RGB:Imf::WRITE_RGBA);
      outFile.setFrameBuffer(ptrd0,1,_width);
      outFile.writePixels(_height);
      delete[] ptrd0;
      return *this;
#endif
    }

    //! Save the image as a Pandore-5 file.
    /**
       \param filename Filename, as a C-string.
       \param colorspace Colorspace data field in output file
       (see <a href="http://www.greyc.ensicaen.fr/~regis/Pandore">Pandore file specifications</a>
       for more information).
    **/
    const CImg<T>& save_pandore(const char *const filename, const unsigned int colorspace=0) const {
      return _save_pandore(0,filename,colorspace);
    }

    //! Save the image as a Pandore-5 file \overload.
    /**
        Same as save_pandore(const char *,unsigned int) const
        with a file stream argument instead of a filename string.
    **/
    const CImg<T>& save_pandore(std::FILE *const file, const unsigned int colorspace=0) const {
      return _save_pandore(file,0,colorspace);
    }

    unsigned int _save_pandore_header_length(unsigned int id, unsigned int *dims, const unsigned int colorspace) const {
      unsigned int nbdims = 0;
      if (id==2 || id==3 || id==4) {
        dims[0] = 1; dims[1] = _width; nbdims = 2;
      }
      if (id==5 || id==6 || id==7) {
        dims[0] = 1; dims[1] = _height; dims[2] = _width; nbdims=3;
      }
      if (id==8 || id==9 || id==10) {
        dims[0] = _spectrum; dims[1] = _depth; dims[2] = _height; dims[3] = _width; nbdims = 4;
      }
      if (id==16 || id==17 || id==18) {
        dims[0] = 3; dims[1] = _height; dims[2] = _width; dims[3] = colorspace; nbdims = 4;
      }
      if (id==19 || id==20 || id==21) {
        dims[0] = 3; dims[1] = _depth; dims[2] = _height; dims[3] = _width; dims[4] = colorspace; nbdims = 5;
      }
      if (id==22 || id==23 || id==25) {
        dims[0] = _spectrum; dims[1] = _width; nbdims = 2;
      }
      if (id==26 || id==27 || id==29) {
        dims[0] = _spectrum; dims[1] = _height; dims[2] = _width; nbdims=3;
      }
      if (id==30 || id==31 || id==33) {
        dims[0] = _spectrum; dims[1] = _depth; dims[2] = _height; dims[3] = _width; nbdims = 4;
      }
      return nbdims;
    }

    const CImg<T>& _save_pandore(std::FILE *const file, const char *const filename,
                                 const unsigned int colorspace) const {
#define __cimg_save_pandore_case(dtype) \
       CImg<dtype> _buffer(size()); \
       dtype *buffer = _buffer._data; \
       const T *ptrs = _data; \
       cimg_foroff(*this,off) *(buffer++) = (dtype)(*(ptrs++)); \
       cimg::fwrite(_buffer._data,size(),nfile)

#define _cimg_save_pandore_case(sy,sz,sv,stype,id) \
      if (!saved && (sy?(sy==_height):true) && (sz?(sz==_depth):true) && \
          (sv?(sv==_spectrum):true) && !std::strcmp(stype,pixel_type())) { \
        unsigned int *iheader = (unsigned int*)(header + 12); \
        nbdims = _save_pandore_header_length((*iheader=id),dims,colorspace); \
        cimg::fwrite(header,36,nfile); \
        if (sizeof(unsigned long)==4) { CImg<ulongT> ndims(5); \
          for (int d = 0; d<5; ++d) ndims[d] = (unsigned long)dims[d]; \
          cimg::fwrite(ndims._data,nbdims,nfile); } \
        else if (sizeof(unsigned int)==4) { CImg<uintT> ndims(5); \
          for (int d = 0; d<5; ++d) ndims[d] = (unsigned int)dims[d]; \
          cimg::fwrite(ndims._data,nbdims,nfile); } \
        else if (sizeof(unsigned short)==4) { CImg<ushortT> ndims(5); \
          for (int d = 0; d<5; ++d) ndims[d] = (unsigned short)dims[d]; \
          cimg::fwrite(ndims._data,nbdims,nfile); } \
        else throw CImgIOException(_cimg_instance \
                                   "save_pandore(): Unsupported datatype for file '%s'.",\
                                   cimg_instance, \
                                   filename?filename:"(FILE*)"); \
        if (id==2 || id==5 || id==8 || id==16 || id==19 || id==22 || id==26 || id==30) { \
          __cimg_save_pandore_case(ucharT); \
        } else if (id==3 || id==6 || id==9 || id==17 || id==20 || id==23 || id==27 || id==31) { \
          if (sizeof(unsigned long)==4) { __cimg_save_pandore_case(ulongT); } \
          else if (sizeof(unsigned int)==4) { __cimg_save_pandore_case(uintT); } \
          else if (sizeof(unsigned short)==4) { __cimg_save_pandore_case(ushortT); } \
          else throw CImgIOException(_cimg_instance \
                                     "save_pandore(): Unsupported datatype for file '%s'.",\
                                     cimg_instance, \
                                     filename?filename:"(FILE*)"); \
        } else if (id==4 || id==7 || id==10 || id==18 || id==21 || id==25 || id==29 || id==33) { \
          if (sizeof(double)==4) { __cimg_save_pandore_case(doubleT); } \
          else if (sizeof(float)==4) { __cimg_save_pandore_case(floatT); } \
          else throw CImgIOException(_cimg_instance \
                                     "save_pandore(): Unsupported datatype for file '%s'.",\
                                     cimg_instance, \
                                     filename?filename:"(FILE*)"); \
        } \
        saved = true; \
      }

      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_pandore(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      unsigned char header[36] = { 'P','A','N','D','O','R','E','0','4',0,0,0,
                                   0,0,0,0,'C','I','m','g',0,0,0,0,0,
                                   'N','o',' ','d','a','t','e',0,0,0,0 };
      unsigned int nbdims, dims[5] = {};
      bool saved = false;
      _cimg_save_pandore_case(1,1,1,"uint8",2);
      _cimg_save_pandore_case(1,1,1,"int8",3);
      _cimg_save_pandore_case(1,1,1,"uint16",3);
      _cimg_save_pandore_case(1,1,1,"int16",3);
      _cimg_save_pandore_case(1,1,1,"uint32",3);
      _cimg_save_pandore_case(1,1,1,"int32",3);
      _cimg_save_pandore_case(1,1,1,"uint64",3);
      _cimg_save_pandore_case(1,1,1,"int64",3);
      _cimg_save_pandore_case(1,1,1,"float32",4);
      _cimg_save_pandore_case(1,1,1,"float64",4);

      _cimg_save_pandore_case(0,1,1,"uint8",5);
      _cimg_save_pandore_case(0,1,1,"int8",6);
      _cimg_save_pandore_case(0,1,1,"uint16",6);
      _cimg_save_pandore_case(0,1,1,"int16",6);
      _cimg_save_pandore_case(0,1,1,"uint32",6);
      _cimg_save_pandore_case(0,1,1,"int32",6);
      _cimg_save_pandore_case(0,1,1,"uint64",6);
      _cimg_save_pandore_case(0,1,1,"int64",6);
      _cimg_save_pandore_case(0,1,1,"float32",7);
      _cimg_save_pandore_case(0,1,1,"float64",7);

      _cimg_save_pandore_case(0,0,1,"uint8",8);
      _cimg_save_pandore_case(0,0,1,"int8",9);
      _cimg_save_pandore_case(0,0,1,"uint16",9);
      _cimg_save_pandore_case(0,0,1,"int16",9);
      _cimg_save_pandore_case(0,0,1,"uint32",9);
      _cimg_save_pandore_case(0,0,1,"int32",9);
      _cimg_save_pandore_case(0,0,1,"uint64",9);
      _cimg_save_pandore_case(0,0,1,"int64",9);
      _cimg_save_pandore_case(0,0,1,"float32",10);
      _cimg_save_pandore_case(0,0,1,"float64",10);

      _cimg_save_pandore_case(0,1,3,"uint8",16);
      _cimg_save_pandore_case(0,1,3,"int8",17);
      _cimg_save_pandore_case(0,1,3,"uint16",17);
      _cimg_save_pandore_case(0,1,3,"int16",17);
      _cimg_save_pandore_case(0,1,3,"uint32",17);
      _cimg_save_pandore_case(0,1,3,"int32",17);
      _cimg_save_pandore_case(0,1,3,"uint64",17);
      _cimg_save_pandore_case(0,1,3,"int64",17);
      _cimg_save_pandore_case(0,1,3,"float32",18);
      _cimg_save_pandore_case(0,1,3,"float64",18);

      _cimg_save_pandore_case(0,0,3,"uint8",19);
      _cimg_save_pandore_case(0,0,3,"int8",20);
      _cimg_save_pandore_case(0,0,3,"uint16",20);
      _cimg_save_pandore_case(0,0,3,"int16",20);
      _cimg_save_pandore_case(0,0,3,"uint32",20);
      _cimg_save_pandore_case(0,0,3,"int32",20);
      _cimg_save_pandore_case(0,0,3,"uint64",20);
      _cimg_save_pandore_case(0,0,3,"int64",20);
      _cimg_save_pandore_case(0,0,3,"float32",21);
      _cimg_save_pandore_case(0,0,3,"float64",21);

      _cimg_save_pandore_case(1,1,0,"uint8",22);
      _cimg_save_pandore_case(1,1,0,"int8",23);
      _cimg_save_pandore_case(1,1,0,"uint16",23);
      _cimg_save_pandore_case(1,1,0,"int16",23);
      _cimg_save_pandore_case(1,1,0,"uint32",23);
      _cimg_save_pandore_case(1,1,0,"int32",23);
      _cimg_save_pandore_case(1,1,0,"uint64",23);
      _cimg_save_pandore_case(1,1,0,"int64",23);
      _cimg_save_pandore_case(1,1,0,"float32",25);
      _cimg_save_pandore_case(1,1,0,"float64",25);

      _cimg_save_pandore_case(0,1,0,"uint8",26);
      _cimg_save_pandore_case(0,1,0,"int8",27);
      _cimg_save_pandore_case(0,1,0,"uint16",27);
      _cimg_save_pandore_case(0,1,0,"int16",27);
      _cimg_save_pandore_case(0,1,0,"uint32",27);
      _cimg_save_pandore_case(0,1,0,"int32",27);
      _cimg_save_pandore_case(0,1,0,"uint64",27);
      _cimg_save_pandore_case(0,1,0,"int64",27);
      _cimg_save_pandore_case(0,1,0,"float32",29);
      _cimg_save_pandore_case(0,1,0,"float64",29);

      _cimg_save_pandore_case(0,0,0,"uint8",30);
      _cimg_save_pandore_case(0,0,0,"int8",31);
      _cimg_save_pandore_case(0,0,0,"uint16",31);
      _cimg_save_pandore_case(0,0,0,"int16",31);
      _cimg_save_pandore_case(0,0,0,"uint32",31);
      _cimg_save_pandore_case(0,0,0,"int32",31);
      _cimg_save_pandore_case(0,0,0,"uint64",31);
      _cimg_save_pandore_case(0,0,0,"int64",31);
      _cimg_save_pandore_case(0,0,0,"float32",33);
      _cimg_save_pandore_case(0,0,0,"float64",33);

      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the image as a raw data file.
    /**
       \param filename Filename, as a C-string.
       \param is_multiplexed Indicates whether the image channels are stored in a multiplexed way (\c true)
         or not (\c false).
       \note The .raw format does not store the image dimensions in the output file,
       so you have to keep track of them somewhere to be able to read the file correctly afterwards.
    **/
    const CImg<T>& save_raw(const char *const filename, const bool is_multiplexed=false) const {
      return _save_raw(0,filename,is_multiplexed);
    }

    //! Save the image as a raw data file \overload.
    /**
       Same as save_raw(const char *,bool) const
       with a file stream argument instead of a filename string.
    **/
    const CImg<T>& save_raw(std::FILE *const file, const bool is_multiplexed=false) const {
      return _save_raw(file,0,is_multiplexed);
    }

    const CImg<T>& _save_raw(std::FILE *const file, const char *const filename, const bool is_multiplexed) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_raw(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      if (pixel_type()==cimg::type<bool>::string()) { // Boolean data (bitwise)
        ulongT siz;
        const unsigned char *const buf = _bool2uchar(siz,is_multiplexed);
        cimg::fwrite(buf,siz,nfile);
        delete[] buf;
      } else { // Non boolean data
        if (!is_multiplexed || _spectrum==1) cimg::fwrite(_data,size(),nfile); // Non-multiplexed
        else { // Multiplexed
          CImg<T> buf(_spectrum);
          cimg_forXYZ(*this,x,y,z) {
            cimg_forC(*this,c) buf[c] = (*this)(x,y,z,c);
            cimg::fwrite(buf._data,_spectrum,nfile);
          }
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    // Return unsigned char buffer that encodes data of a CImg<bool> instance bitwise.
    // (the returned buffer must be deallocated afterwards using delete[]).
    const unsigned char *_bool2uchar(ulongT &siz, const bool is_multiplexed) const {
      const ulongT _siz = size();
      siz = _siz/8 + (_siz%8?1:0);
      unsigned char *const buf = new unsigned char[siz], *ptrd = buf, val = 0, bit = 0;

      if (!is_multiplexed || _spectrum==1) // Non-multiplexed
        cimg_for(*this,ptrs,T) { (val<<=1)|=(*ptrs?1:0); if (++bit==8) { *(ptrd++) = val; val = bit = 0; }}
      else // Multiplexed
        cimg_forXYZ(*this,x,y,z) cimg_forC(*this,c) {
          (val<<=1)|=((*this)(x,y,z,c)?1:0); if (++bit==8) { *(ptrd++) = val; val = bit = 0; }
        }
      if (bit) *ptrd = (unsigned char)(val<<(8-bit));
      return buf;
    }

    // Fill CImg<T> instance from bitwise data encoded in an unsigned char buffer.
    void _uchar2bool(const unsigned char *buf, const ulongT siz, const bool is_multiplexed) {
      const ulongT S = std::min(siz*8,size());
      const unsigned char *ptrs = buf;
      unsigned char val = 0, mask = 0;
      T *ptrd = _data;
      if (S && (!is_multiplexed || _spectrum==1)) // Non-multiplexed
        for (ulongT off = 0; off<S; ++off) {
          if (!(mask>>=1)) { val = *(ptrs++); mask = 128; }
          *(ptrd++) = (T)((val&mask)?1:0);
        }
      else if (S) { // Multiplexed
        ulongT off = 0;
        for (int z = 0; z<depth() && off<=S; ++z)
          for (int y = 0; y<height() && off<=S; ++y)
            for (int x = 0; x<width() && off<=S; ++x)
              for (int c = 0; c<spectrum() && off<=S; ++c) {
                if (!(mask>>=1)) { val = *(ptrs++); ++off; mask = 128; }
                (*this)(x,y,z,c) = (T)((val&mask)?1:0);
              }
      }
    }

    //! Save the image as a .yuv video file.
    /**
       \param filename Filename, as a C-string.
       \param chroma_subsampling Type of chroma subsampling. Can be <tt>{ 420 | 422 | 444 }</tt>.
       \param is_rgb Indicates whether pixel values of the instance image are RGB-coded (\c true) or
         YUV-coded (\c false).
       \note Each slice of the instance image is considered to be a single frame of the output video file.
    **/
    const CImg<T>& save_yuv(const char *const filename,
                            const unsigned int chroma_subsampling=444,
                            const bool is_rgb=true) const {
      CImgList<T>(*this,true).save_yuv(filename,chroma_subsampling,is_rgb);
      return *this;
    }

    //! Save the image as a .yuv video file \overload.
    /**
       Same as save_yuv(const char*,const unsigned int,const bool) const
       with a file stream argument instead of a filename string.
    **/
    const CImg<T>& save_yuv(std::FILE *const file,
                            const unsigned int chroma_subsampling=444,
                            const bool is_rgb=true) const {
      CImgList<T>(*this,true).save_yuv(file,chroma_subsampling,is_rgb);
      return *this;
    }

    //! Save 3D object as an Object File Format (.off) file.
    /**
       \param filename Filename, as a C-string.
       \param primitives List of 3D object primitives.
       \param colors List of 3D object colors.
       \note
       - Instance image contains the vertices data of the 3D object.
       - Textured, transparent or sphere-shaped primitives cannot be managed by the .off file format.
       Such primitives will be lost or simplified during file saving.
       - The .off file format is <a href="http://people.sc.fsu.edu/~jburkardt/html/off_format.html">described here</a>.
    **/
    template<typename tf, typename tc>
    const CImg<T>& save_off(const CImgList<tf>& primitives, const CImgList<tc>& colors,
                            const char *const filename) const {
      return _save_off(primitives,colors,0,filename);
    }

    //! Save 3D object as an Object File Format (.off) file \overload.
    /**
       Same as save_off(const CImgList<tf>&,const CImgList<tc>&,const char*) const
       with a file stream argument instead of a filename string.
    **/
    template<typename tf, typename tc>
    const CImg<T>& save_off(const CImgList<tf>& primitives, const CImgList<tc>& colors,
                            std::FILE *const file) const {
      return _save_off(primitives,colors,file,0);
    }

    template<typename tf, typename tc>
    const CImg<T>& _save_off(const CImgList<tf>& primitives, const CImgList<tc>& colors,
                             std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_off(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty())
        throw CImgInstanceException(_cimg_instance
                                    "save_off(): Empty instance, for file '%s'.",
                                    cimg_instance,
                                    filename?filename:"(FILE*)");

      CImgList<T> opacities;
      CImg<charT> error_message(1024);
      if (!is_object3d(primitives,colors,opacities,true,error_message))
        throw CImgInstanceException(_cimg_instance
                                    "save_off(): Invalid specified 3D object, for file '%s' (%s).",
                                    cimg_instance,
                                    filename?filename:"(FILE*)",error_message.data());

      const CImg<tc> default_color(1,3,1,1,(tc)std::min((int)cimg::type<tc>::max(),200));
      std::FILE *const nfile = file?file:cimg::fopen(filename,"w");
      unsigned int supported_primitives = 0;
      cimglist_for(primitives,l) if (primitives[l].size()!=5) ++supported_primitives;
      std::fprintf(nfile,"OFF\n%u %u %u\n",_width,supported_primitives,3*primitives._width);
      cimg_forX(*this,i) std::fprintf(nfile,"%f %f %f\n",
                                      (float)((*this)(i,0)),(float)((*this)(i,1)),(float)((*this)(i,2)));
      cimglist_for(primitives,l) {
        const CImg<tc>& color = l<colors.width()?colors[l]:default_color;
        const unsigned int psiz = primitives[l].size(), csiz = color.size();
        const float r = color[0]/255.f, g = (csiz>1?color[1]:r)/255.f, b = (csiz>2?color[2]:g)/255.f;
        switch (psiz) {
        case 1 : std::fprintf(nfile,"1 %u %f %f %f\n",
                              (unsigned int)primitives(l,0),r,g,b); break;
        case 2 : std::fprintf(nfile,"2 %u %u %f %f %f\n",
                              (unsigned int)primitives(l,0),(unsigned int)primitives(l,1),r,g,b); break;
        case 3 : std::fprintf(nfile,"3 %u %u %u %f %f %f\n",
                              (unsigned int)primitives(l,0),(unsigned int)primitives(l,2),
                              (unsigned int)primitives(l,1),r,g,b); break;
        case 4 : std::fprintf(nfile,"4 %u %u %u %u %f %f %f\n",
                              (unsigned int)primitives(l,0),(unsigned int)primitives(l,3),
                              (unsigned int)primitives(l,2),(unsigned int)primitives(l,1),r,g,b); break;
        case 5 : break;
        case 6 : {
          const unsigned int xt = (unsigned int)primitives(l,2), yt = (unsigned int)primitives(l,3);
          const float
            rt = color.atXY(xt,yt,0)/255.f,
            gt = (csiz>1?color.atXY(xt,yt,1):r)/255.f,
            bt = (csiz>2?color.atXY(xt,yt,2):g)/255.f;
          std::fprintf(nfile,"2 %u %u %f %f %f\n",
                       (unsigned int)primitives(l,0),(unsigned int)primitives(l,1),rt,gt,bt);
        } break;
        case 9 : {
          const unsigned int xt = (unsigned int)primitives(l,3), yt = (unsigned int)primitives(l,4);
          const float
            rt = color.atXY(xt,yt,0)/255.f,
            gt = (csiz>1?color.atXY(xt,yt,1):r)/255.f,
            bt = (csiz>2?color.atXY(xt,yt,2):g)/255.f;
          std::fprintf(nfile,"3 %u %u %u %f %f %f\n",
                       (unsigned int)primitives(l,0),(unsigned int)primitives(l,2),
                       (unsigned int)primitives(l,1),rt,gt,bt);
        } break;
        case 12 : {
          const unsigned int xt = (unsigned int)primitives(l,4), yt = (unsigned int)primitives(l,5);
          const float
            rt = color.atXY(xt,yt,0)/255.f,
            gt = (csiz>1?color.atXY(xt,yt,1):r)/255.f,
            bt = (csiz>2?color.atXY(xt,yt,2):g)/255.f;
          std::fprintf(nfile,"4 %u %u %u %u %f %f %f\n",
                       (unsigned int)primitives(l,0),(unsigned int)primitives(l,3),
                       (unsigned int)primitives(l,2),(unsigned int)primitives(l,1),rt,gt,bt);
        } break;
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save volumetric image as a video (using the OpenCV library when available).
    /**
      \param filename Filename to write data to.
      \param fps Number of frames per second.
      \param codec Type of compression (See http://www.fourcc.org/codecs.php to see available codecs).
      \param keep_open Indicates whether the video writer associated with the specified filename
        must be kept open (to allow frames to be added in the same file afterwards).
    **/
    const CImg<T>& save_video(const char *const filename, const unsigned int fps=25,
                              const char *codec=0, const bool keep_open=false) const {
      if (is_empty()) { CImgList<T>().save_video(filename,fps,codec,keep_open); return *this; }
      CImgList<T> list;
      get_split('z').move_to(list);
      list.save_video(filename,fps,codec,keep_open);
      return *this;
    }

    //! Save volumetric image as a video, using ffmpeg external binary.
    /**
       \param filename Filename, as a C-string.
       \param fps Video framerate.
       \param codec Video codec, as a C-string.
       \param bitrate Video bitrate.
       \note
       - Each slice of the instance image is considered to be a single frame of the output video file.
       - This function uses \c ffmpeg, an external executable binary provided by
         <a href="http://www.ffmpeg.org">FFmpeg</a>.
       It must be installed for the function to succeed.
    **/
    const CImg<T>& save_ffmpeg_external(const char *const filename, const unsigned int fps=25,
                                        const char *const codec=0, const unsigned int bitrate=2048) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_ffmpeg_external(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

      CImgList<T> list;
      get_split('z').move_to(list);
      list.save_ffmpeg_external(filename,fps,codec,bitrate);
      return *this;
    }

    //! Save the image using gzip external binary.
    /**
       \param filename Filename, as a C-string.
       \note This function uses \c gzip, an external executable binary provided by
         <a href="//http://www.gzip.org">gzip</a>.
       It must be installed for the function to succeed.
    **/
    const CImg<T>& save_gzip_external(const char *const filename) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_gzip_external(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

      CImg<charT> command(1024), filename_tmp(256), body(256);
      const char
        *ext = cimg::split_filename(filename,body),
        *ext2 = cimg::split_filename(body,0);
      do {
        if (!cimg::strcasecmp(ext,"gz")) {
          if (*ext2) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                   cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext2);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        } else {
          if (*ext) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                  cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        }
      } while (cimg::path_exists(filename_tmp));
      save(filename_tmp);
      cimg_snprintf(command,command._width,"\"%s\" -c \"%s\" > \"%s\"",
                    cimg::gzip_path(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    CImg<charT>::string(filename)._system_strescape().data());
      if (cimg::system(command,cimg::gzip_path())!=0)
        throw CImgIOException(_cimg_instance
                              "save_gzip_external(): Failed to save file '%s' with external command 'gzip'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimg_instance
                              "save_gzip_external(): Failed to save file '%s' with external command 'gzip'.",
                              cimg_instance,
                              filename);

      std::remove(filename_tmp);
      return *this;
    }

    //! Save the image using GraphicsMagick's external binary.
    /**
       \param filename Filename, as a C-string.
       \param quality Image quality (expressed in percent), when the file format supports it.
       \note This function uses \c gm, an external executable binary provided by
         <a href="http://www.graphicsmagick.org">GraphicsMagick</a>.
       It must be installed for the function to succeed.
    **/
    const CImg<T>& save_graphicsmagick_external(const char *const filename, const unsigned int quality=100) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_graphicsmagick_external(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_other(): File '%s', saving a volumetric image with an external call to "
                   "GraphicsMagick only writes the first image slice.",
                   cimg_instance,filename);

#ifdef cimg_use_png
#define _cimg_sge_extension1 "png"
#define _cimg_sge_extension2 "png"
#else
#define _cimg_sge_extension1 "pgm"
#define _cimg_sge_extension2 "ppm"
#endif
      CImg<charT> command(1024), filename_tmp(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),
                      _spectrum==1?_cimg_sge_extension1:_cimg_sge_extension2);
      } while (cimg::path_exists(filename_tmp));

#ifdef cimg_use_png
      save_png(filename_tmp);
#else
      save_pnm(filename_tmp);
#endif
      cimg_snprintf(command,command._width,"\"%s\" convert -quality %u \"%s\" \"%s\"",
                    cimg::graphicsmagick_path(),quality,
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    CImg<charT>::string(filename)._system_strescape().data());
      if (cimg::system(command,cimg::graphicsmagick_path())!=0)
        throw CImgIOException(_cimg_instance
                              "save_graphicsmagick_external(): Failed to save file '%s' with external command 'gm'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimg_instance
                              "save_graphicsmagick_external(): Failed to save file '%s' with external command 'gm'.",
                              cimg_instance,
                              filename);

      std::remove(filename_tmp);
      return *this;
    }

    //! Save the image using ImageMagick's external binary.
    /**
       \param filename Filename, as a C-string.
       \param quality Image quality (expressed in percent), when the file format supports it.
       \note This function uses \c convert, an external executable binary provided by
       <a href="http://www.imagemagick.org">ImageMagick</a>.
       It must be installed for the function to succeed.
    **/
    const CImg<T>& save_imagemagick_external(const char *const filename, const unsigned int quality=100) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_imagemagick_external(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_other(): File '%s', saving a volumetric image with an external call to "
                   "ImageMagick only writes the first image slice.",
                   cimg_instance,filename);
#ifdef cimg_use_png
#define _cimg_sie_extension1 "png"
#define _cimg_sie_extension2 "png"
#else
#define _cimg_sie_extension1 "pgm"
#define _cimg_sie_extension2 "ppm"
#endif
      CImg<charT> command(1024), filename_tmp(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",cimg::temporary_path(),
                      cimg_directory_separator,cimg::filenamerand(),
                      _spectrum==1?_cimg_sie_extension1:_cimg_sie_extension2);
      } while (cimg::path_exists(filename_tmp));
#ifdef cimg_use_png
      save_png(filename_tmp);
#else
      save_pnm(filename_tmp);
#endif
      const char *magick_path = cimg::imagemagick_path();
      cimg_snprintf(command,command._width,"%s -quality %u \"%s\" \"%s\"",
                    magick_path,quality,
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    CImg<charT>::string(filename)._system_strescape().data());
      if (cimg::system(command,magick_path)!=0)
        throw CImgIOException(_cimg_instance
                              "save_imagemagick_external(): Failed to save file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimg_instance
                              "save_imagemagick_external(): Failed to save file '%s' with "
                              "external command 'magick/convert'.",
                              cimg_instance,
                              filename);

      std::remove(filename_tmp);
      return *this;
    }

    //! Save the image as a Dicom file.
    /**
       \param filename Filename, as a C-string.
       \note This function uses \c medcon, an external executable binary provided by
         <a href="http://xmedcon.sourceforge.net">(X)Medcon</a>.
       It must be installed for the function to succeed.
    **/
    const CImg<T>& save_medcon_external(const char *const filename) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_medcon_external(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

      CImg<charT> command(1024), filename_tmp(256), body(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s.hdr",cimg::filenamerand());
      } while (cimg::path_exists(filename_tmp));
      save_analyze(filename_tmp);
      cimg_snprintf(command,command._width,"\"%s\" -w -c dicom -o \"%s\" -f \"%s\"",
                    cimg::medcon_path(),
                    CImg<charT>::string(filename)._system_strescape().data(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data());
      if (cimg::system(command,cimg::medcon_path())!=0)
        throw CImgIOException(_cimg_instance
                                "save_medcon_external(): Failed to save file '%s' with external command 'medcon'.",
                                cimg_instance,
                                filename);
      std::remove(filename_tmp);
      cimg::split_filename(filename_tmp,body);
      cimg_snprintf(filename_tmp,filename_tmp._width,"%s.img",body._data);
      std::remove(filename_tmp);

      if (!cimg::path_exists(filename)) {
        cimg_snprintf(command,command._width,"m000-%s",filename);
        if (!cimg::path_exists(command)) {
          cimg::fclose(cimg::fopen(filename,"r"));
          throw CImgIOException(_cimg_instance
                                "save_medcon_external(): Failed to save file '%s' with external command 'medcon'.",
                                cimg_instance,
                                filename);
        }
      }
      std::rename(command,filename);
      return *this;
    }

    // Save the image for non natively supported formats.
    /**
       \param filename Filename, as a C-string.
       \param quality Image quality (expressed in percent), when the file format supports it.
       \note
       - The filename extension indicates the desired file format.
       - This function tries to save the instance image as a file, using external tools from
       <a href="http://www.imagemagick.org">ImageMagick</a> or
       <a href="http://www.graphicsmagick.org">GraphicsMagick</a>.
         At least one of these tool must be installed for the function to succeed.
       - It is recommended to use the generic function save(const char*, int) const instead,
         as it can handle some file formats natively.
    **/
    const CImg<T>& save_other(const char *const filename, const unsigned int quality=100) const {
      if (!filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_other(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_other(): File '%s', saving a volumetric image with an external call to "
                   "ImageMagick or GraphicsMagick only writes the first image slice.",
                   cimg_instance,filename);

      const unsigned int omode = cimg::exception_mode();
      bool is_saved = true;
      cimg::exception_mode(0);
      try { save_magick(filename); }
      catch (CImgException&) {
        try { save_imagemagick_external(filename,quality); }
        catch (CImgException&) {
          try { save_graphicsmagick_external(filename,quality); }
          catch (CImgException&) {
            is_saved = false;
          }
        }
      }
      cimg::exception_mode(omode);
      if (!is_saved)
        throw CImgIOException(_cimg_instance
                              "save_other(): Failed to save file '%s'. Format is not natively supported, "
                              "and no external commands succeeded.",
                              cimg_instance,
                              filename);
      return *this;
    }

    //! Serialize a CImg<T> instance into a raw CImg<unsigned char> buffer.
    /**
       \param is_compressed Indicates that zlib compression must be used for serialization
       (this requires 'cimg_use_zlib' been enabled).
       \param header_size Reserve empty bytes as a starting header.
    **/
    CImg<ucharT> get_serialize(const bool is_compressed=false, const unsigned int header_size=0) const {
      return CImgList<T>(*this,true).get_serialize(is_compressed,header_size);
    }

    // [internal] Return a 40x38 color logo of a 'danger' item.
    static CImg<T> logo40x38() {
      CImg<T> res(40,38,1,3);
      const unsigned char *ptrs = cimg::logo40x38_data();
      T *ptr1 = res.data(0,0,0,0), *ptr2 = res.data(0,0,0,1), *ptr3 = res.data(0,0,0,2);
      for (ulongT off = 0; off<(ulongT)res._width*res._height;) {
        const unsigned char n = *(ptrs++), r = *(ptrs++), g = *(ptrs++), b = *(ptrs++);
        for (unsigned int l = 0; l<n; ++off, ++l) { *(ptr1++) = (T)r; *(ptr2++) = (T)g; *(ptr3++) = (T)b; }
      }
      return res;
    }

    //@}
  }; // struct CImg { ...

  /*
   #-----------------------------------------
   #
   #
   #
   # Definition of the CImgList<T> structure
   #
   #
   #
   #------------------------------------------
  */
  //! Represents a list of images CImg<T>.
  template<typename T>
  struct CImgList {
    unsigned int _width, _allocated_width;
    CImg<T> *_data;

    //! Simple iterator type to loop through each image of a list.
    /**
       \note
       - The \c CImgList<T>::iterator type is defined as a <tt>CImg<T>*</tt>.
       - You may use it like this:
       \code
       CImgList<> list; // Assuming this image list is not empty
       for (CImgList<>::iterator it = list.begin(); it<list.end(); ++it) (*it).mirror('x');
       \endcode
       - Using the loop macro \c cimglist_for is another (more concise) alternative:
       \code
       cimglist_for(list,l) list[l].mirror('x');
       \endcode
    **/
    typedef CImg<T>* iterator;

    //! Simple const iterator type, to loop through each image of a \c const list instance.
    /**
       \note
       - The \c CImgList<T>::const_iterator type is defined to be a <tt>const CImg<T>*</tt>.
       - Similar to CImgList<T>::iterator, but for constant list instances.
    **/
    typedef const CImg<T>* const_iterator;

    //! Pixel value type.
    /**
       Refer to the pixels value type of the images in the list.
       \note
       - The \c CImgList<T>::value_type type of a \c CImgList<T> is defined to be a \c T.
         It is then similar to CImg<T>::value_type.
       - \c CImgList<T>::value_type is actually not used in \CImg functions. It has been mainly defined for
         compatibility with STL naming conventions.
    **/
    typedef T value_type;

    // Define common types related to template type T.
    typedef typename cimg::superset<T,bool>::type Tbool;
    typedef typename cimg::superset<T,unsigned char>::type Tuchar;
    typedef typename cimg::superset<T,char>::type Tchar;
    typedef typename cimg::superset<T,unsigned short>::type Tushort;
    typedef typename cimg::superset<T,short>::type Tshort;
    typedef typename cimg::superset<T,unsigned int>::type Tuint;
    typedef typename cimg::superset<T,int>::type Tint;
    typedef typename cimg::superset<T,cimg_ulong>::type Tulong;
    typedef typename cimg::superset<T,cimg_long>::type Tlong;
    typedef typename cimg::superset<T,float>::type Tfloat;
    typedef typename cimg::superset<T,double>::type Tdouble;
    typedef typename cimg::last<T,bool>::type boolT;
    typedef typename cimg::last<T,unsigned char>::type ucharT;
    typedef typename cimg::last<T,char>::type charT;
    typedef typename cimg::last<T,unsigned short>::type ushortT;
    typedef typename cimg::last<T,short>::type shortT;
    typedef typename cimg::last<T,unsigned int>::type uintT;
    typedef typename cimg::last<T,int>::type intT;
    typedef typename cimg::last<T,cimg_ulong>::type ulongT;
    typedef typename cimg::last<T,cimg_long>::type longT;
    typedef typename cimg::last<T,cimg_uint64>::type uint64T;
    typedef typename cimg::last<T,cimg_int64>::type int64T;
    typedef typename cimg::last<T,float>::type floatT;
    typedef typename cimg::last<T,double>::type doubleT;

    //@}
    //---------------------------
    //
    //! \name Plugins
    //@{
    //---------------------------
#ifdef cimglist_plugin
#include cimglist_plugin
#endif
#ifdef cimglist_plugin1
#include cimglist_plugin1
#endif
#ifdef cimglist_plugin2
#include cimglist_plugin2
#endif
#ifdef cimglist_plugin3
#include cimglist_plugin3
#endif
#ifdef cimglist_plugin4
#include cimglist_plugin4
#endif
#ifdef cimglist_plugin5
#include cimglist_plugin5
#endif
#ifdef cimglist_plugin6
#include cimglist_plugin6
#endif
#ifdef cimglist_plugin7
#include cimglist_plugin7
#endif
#ifdef cimglist_plugin8
#include cimglist_plugin8
#endif

    //@}
    //--------------------------------------------------------
    //
    //! \name Constructors / Destructor / Instance Management
    //@{
    //--------------------------------------------------------

    //! Destructor.
    /**
       Destroy current list instance.
       \note
       - Any allocated buffer is deallocated.
       - Destroying an empty list does nothing actually.
     **/
    ~CImgList() {
      delete[] _data;
    }

    //! Default constructor.
    /**
       Construct a new empty list instance.
       \note
       - An empty list has no pixel data and its dimension width() is set to \c 0, as well as its
         image buffer pointer data().
       - An empty list may be reassigned afterwards, with the family of the assign() functions.
         In all cases, the type of pixels stays \c T.
     **/
    CImgList():
      _width(0),_allocated_width(0),_data(0) {}

    //! Construct list containing empty images.
    /**
       \param n Number of empty images.
       \note Useful when you know in advance the number of images you want to manage, as
       it will allocate the right amount of memory for the list, without needs for reallocation
       (that may occur when starting from an empty list and inserting several images in it).
    **/
    explicit CImgList(const unsigned int n):_width(n) {
      if (n) _data = new CImg<T>[_allocated_width = std::max(16U,(unsigned int)cimg::nearest_pow2(n))];
      else { _allocated_width = 0; _data = 0; }
    }

    //! Construct list containing images of specified size.
    /**
       \param n Number of images.
       \param width Width of images.
       \param height Height of images.
       \param depth Depth of images.
       \param spectrum Number of channels of images.
       \note Pixel values are not initialized and may probably contain garbage.
    **/
    CImgList(const unsigned int n, const unsigned int width, const unsigned int height=1,
             const unsigned int depth=1, const unsigned int spectrum=1):
      _width(0),_allocated_width(0),_data(0) {
      assign(n);
      cimglist_apply(*this,assign)(width,height,depth,spectrum);
    }

    //! Construct list containing images of specified size, and initialize pixel values.
    /**
       \param n Number of images.
       \param width Width of images.
       \param height Height of images.
       \param depth Depth of images.
       \param spectrum Number of channels of images.
       \param val Initialization value for images pixels.
    **/
    CImgList(const unsigned int n, const unsigned int width, const unsigned int height,
             const unsigned int depth, const unsigned int spectrum, const T& val):
      _width(0),_allocated_width(0),_data(0) {
      assign(n);
      cimglist_apply(*this,assign)(width,height,depth,spectrum,val);
    }

    //! Construct list containing copies of an input image.
    /**
       \param n Number of images.
       \param img Input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of \c img.
    **/
    template<typename t>
    CImgList(const unsigned int n, const CImg<t>& img, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(n);
      cimglist_apply(*this,assign)(img,is_shared);
    }

    //! Construct list from one image.
    /**
       \param img Input image to copy in the constructed list.
       \param is_shared Indicates whether the element of the list is a shared or non-shared copy of \c img.
     **/
    template<typename t>
    explicit CImgList(const CImg<t>& img, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(1);
      _data[0].assign(img,is_shared);
    }

    //! Construct list from two images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
     **/
    template<typename t1, typename t2>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(2);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared);
    }

    //! Construct list from three images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(3);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
    }

    //! Construct list from four images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param img4 Fourth input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3, typename t4>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
             const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(4);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared);
    }

    //! Construct list from five images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param img4 Fourth input image to copy in the constructed list.
       \param img5 Fifth input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
             const CImg<t5>& img5, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(5);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared);
    }

    //! Construct list from six images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param img4 Fourth input image to copy in the constructed list.
       \param img5 Fifth input image to copy in the constructed list.
       \param img6 Sixth input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
             const CImg<t5>& img5, const CImg<t6>& img6, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(6);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
    }

    //! Construct list from seven images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param img4 Fourth input image to copy in the constructed list.
       \param img5 Fifth input image to copy in the constructed list.
       \param img6 Sixth input image to copy in the constructed list.
       \param img7 Seventh input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6, typename t7>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
             const CImg<t5>& img5, const CImg<t6>& img6, const CImg<t7>& img7, const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(7);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
      _data[6].assign(img7,is_shared);
    }

    //! Construct list from eight images.
    /**
       \param img1 First input image to copy in the constructed list.
       \param img2 Second input image to copy in the constructed list.
       \param img3 Third input image to copy in the constructed list.
       \param img4 Fourth input image to copy in the constructed list.
       \param img5 Fifth input image to copy in the constructed list.
       \param img6 Sixth input image to copy in the constructed list.
       \param img7 Seventh input image to copy in the constructed list.
       \param img8 Eighth input image to copy in the constructed list.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6, typename t7, typename t8>
    CImgList(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
             const CImg<t5>& img5, const CImg<t6>& img6, const CImg<t7>& img7, const CImg<t8>& img8,
             const bool is_shared=false):
      _width(0),_allocated_width(0),_data(0) {
      assign(8);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
      _data[6].assign(img7,is_shared); _data[7].assign(img8,is_shared);
    }

    //! Construct list copy.
    /**
       \param list Input list to copy.
       \note The shared state of each element of the constructed list is kept the same as in \c list.
    **/
    template<typename t>
    CImgList(const CImgList<t>& list):_width(0),_allocated_width(0),_data(0) {
      assign(list._width);
      cimglist_for(*this,l) _data[l].assign(list[l],false);
    }

    //! Construct list copy \specialization.
    CImgList(const CImgList<T>& list):_width(0),_allocated_width(0),_data(0) {
      assign(list._width);
      cimglist_for(*this,l) _data[l].assign(list[l],list[l]._is_shared);
    }

    //! Construct list copy, and force the shared state of the list elements.
    /**
       \param list Input list to copy.
       \param is_shared Indicates whether the elements of the list are shared or non-shared copies of input images.
    **/
    template<typename t>
    CImgList(const CImgList<t>& list, const bool is_shared):_width(0),_allocated_width(0),_data(0) {
      assign(list._width);
      cimglist_for(*this,l) _data[l].assign(list[l],is_shared);
    }

    //! Construct list by reading the content of a file.
    /**
       \param filename Filename, as a C-string.
    **/
    explicit CImgList(const char *const filename):_width(0),_allocated_width(0),_data(0) {
      assign(filename);
    }

    //! Construct list from the content of a display window.
    /**
       \param disp Display window to get content from.
       \note Constructed list contains a single image only.
    **/
    explicit CImgList(const CImgDisplay& disp):_width(0),_allocated_width(0),_data(0) {
      assign(disp);
    }

    //! Return a list with elements being shared copies of images in the list instance.
    /**
      \note <tt>list2 = list1.get_shared()</tt> is equivalent to <tt>list2.assign(list1,true)</tt>.
    **/
    CImgList<T> get_shared() {
      CImgList<T> res(_width);
      cimglist_for(*this,l) res[l].assign(_data[l],true);
      return res;
    }

    //! Return a list with elements being shared copies of images in the list instance \const.
    const CImgList<T> get_shared() const {
      CImgList<T> res(_width);
      cimglist_for(*this,l) res[l].assign(_data[l],true);
      return res;
    }

    //! Destructor \inplace.
    /**
       \see CImgList().
    **/
    CImgList<T>& assign() {
      delete[] _data;
      _width = _allocated_width = 0;
      _data = 0;
      return *this;
    }

    //! Destructor \inplace.
    /**
       Equivalent to assign().
       \note Only here for compatibility with STL naming conventions.
    **/
    CImgList<T>& clear() {
      return assign();
    }

    //! Construct list containing empty images \inplace.
    /**
       \see CImgList(unsigned int).
    **/
    CImgList<T>& assign(const unsigned int n) {
      if (!n) return assign();
      if (_allocated_width<n || _allocated_width>(n<<2)) {
        delete[] _data;
        _data = new CImg<T>[_allocated_width = std::max(16U,(unsigned int)cimg::nearest_pow2(n))];
      }
      _width = n;
      return *this;
    }

    //! Construct list containing images of specified size \inplace.
    /**
       \see CImgList(unsigned int, unsigned int, unsigned int, unsigned int, unsigned int).
    **/
    CImgList<T>& assign(const unsigned int n, const unsigned int width, const unsigned int height=1,
                        const unsigned int depth=1, const unsigned int spectrum=1) {
      assign(n);
      cimglist_apply(*this,assign)(width,height,depth,spectrum);
      return *this;
    }

    //! Construct list containing images of specified size, and initialize pixel values \inplace.
    /**
       \see CImgList(unsigned int, unsigned int, unsigned int, unsigned int, unsigned int, const T).
    **/
    CImgList<T>& assign(const unsigned int n, const unsigned int width, const unsigned int height,
                        const unsigned int depth, const unsigned int spectrum, const T& val) {
      assign(n);
      cimglist_apply(*this,assign)(width,height,depth,spectrum,val);
      return *this;
    }

    //! Construct list containing copies of an input image \inplace.
    /**
       \see CImgList(unsigned int, const CImg<t>&, bool).
    **/
    template<typename t>
    CImgList<T>& assign(const unsigned int n, const CImg<t>& img, const bool is_shared=false) {
      assign(n);
      cimglist_apply(*this,assign)(img,is_shared);
      return *this;
    }

    //! Construct list from one image \inplace.
    /**
       \see CImgList(const CImg<t>&, bool).
    **/
    template<typename t>
    CImgList<T>& assign(const CImg<t>& img, const bool is_shared=false) {
      assign(1);
      _data[0].assign(img,is_shared);
      return *this;
    }

    //! Construct list from two images \inplace.
    /**
       \see CImgList(const CImg<t>&, const CImg<t>&, bool).
    **/
    template<typename t1, typename t2>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const bool is_shared=false) {
      assign(2);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared);
      return *this;
    }

    //! Construct list from three images \inplace.
    /**
       \see CImgList(const CImg<t>&, const CImg<t>&, const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const bool is_shared=false) {
      assign(3);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      return *this;
    }

    //! Construct list from four images \inplace.
    /**
       \see CImgList(const CImg<t>&, const CImg<t>&, const CImg<t>&, const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3, typename t4>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
                        const bool is_shared=false) {
      assign(4);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared);
      return *this;
    }

    //! Construct list from five images \inplace.
    /**
       \see CImgList(const CImg<t>&, const CImg<t>&, const CImg<t>&, const CImg<t>&, const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
                        const CImg<t5>& img5, const bool is_shared=false) {
      assign(5);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared);
      return *this;
    }

    //! Construct list from six images \inplace.
    /**
       \see CImgList(const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
                        const CImg<t5>& img5, const CImg<t6>& img6, const bool is_shared=false) {
      assign(6);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
      return *this;
    }

    //! Construct list from seven images \inplace.
    /**
       \see CImgList(const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,
       const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6, typename t7>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
                        const CImg<t5>& img5, const CImg<t6>& img6, const CImg<t7>& img7, const bool is_shared=false) {
      assign(7);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
      _data[6].assign(img7,is_shared);
      return *this;
    }

    //! Construct list from eight images \inplace.
    /**
       \see CImgList(const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,const CImg<t>&,
       const CImg<t>&, const CImg<t>&, bool).
    **/
    template<typename t1, typename t2, typename t3, typename t4, typename t5, typename t6, typename t7, typename t8>
    CImgList<T>& assign(const CImg<t1>& img1, const CImg<t2>& img2, const CImg<t3>& img3, const CImg<t4>& img4,
                        const CImg<t5>& img5, const CImg<t6>& img6, const CImg<t7>& img7, const CImg<t8>& img8,
                        const bool is_shared=false) {
      assign(8);
      _data[0].assign(img1,is_shared); _data[1].assign(img2,is_shared); _data[2].assign(img3,is_shared);
      _data[3].assign(img4,is_shared); _data[4].assign(img5,is_shared); _data[5].assign(img6,is_shared);
      _data[6].assign(img7,is_shared); _data[7].assign(img8,is_shared);
      return *this;
    }

    //! Construct list as a copy of an existing list and force the shared state of the list elements \inplace.
    /**
      \see CImgList(const CImgList<t>&, bool is_shared).
    **/
    template<typename t>
    CImgList<T>& assign(const CImgList<t>& list, const bool is_shared=false) {
      cimg::unused(is_shared);
      assign(list._width);
      cimglist_for(*this,l) _data[l].assign(list[l],false);
      return *this;
    }

    //! Construct list as a copy of an existing list and force shared state of elements \inplace \specialization.
    CImgList<T>& assign(const CImgList<T>& list, const bool is_shared=false) {
      if (this==&list) return *this;
      CImgList<T> res(list._width);
      cimglist_for(res,l) res[l].assign(list[l],is_shared);
      return res.move_to(*this);
    }

    //! Construct list by reading the content of a file \inplace.
    /**
      \see CImgList(const char *const).
    **/
    CImgList<T>& assign(const char *const filename) {
      return load(filename);
    }

    //! Construct list from the content of a display window \inplace.
    /**
      \see CImgList(const CImgDisplay&).
    **/
    CImgList<T>& assign(const CImgDisplay &disp) {
      return assign(CImg<T>(disp));
    }

    //! Transfers the content of the list instance to another list.
    /**
       \param list Destination list.
       \note When returning, the current list instance is empty and the initial content of \c list is destroyed.
    **/
    template<typename t>
    CImgList<t>& move_to(CImgList<t>& list) {
      list.assign(_width);
      cimglist_for(*this,l) if (_data[l]._is_shared) { list[l].assign(_data[l]); _data[l].assign(); }
      cimglist_for(*this,l) if (_data[l]) _data[l].move_to(list[l]);
      assign();
      return list;
    }

    //! Transfers the content of the list instance at a specified position in another list.
    /**
       \param list Destination list.
       \param pos Index of the insertion in the list.
       \note When returning, the list instance is empty and the initial content of \c list is preserved
       (only images indexes may be modified).
     **/
    template<typename t>
    CImgList<t>& move_to(CImgList<t>& list, const unsigned int pos) {
      if (is_empty()) return list;
      const unsigned int npos = pos>list._width?list._width:pos;
      list.insert(_width,npos);
      cimglist_for(*this,l) if (_data[l]._is_shared) { list[npos + l].assign(_data[l]); _data[l].assign(); }
      cimglist_for(*this,l) if (_data[l]) _data[l].move_to(list[npos + l]);
      assign();
      return list;
    }

    //! Swap all fields between two list instances.
    /**
       \param list List to swap fields with.
       \note Can be used to exchange the content of two lists in a fast way.
    **/
    CImgList<T>& swap(CImgList<T>& list) {
      cimg::swap(_width,list._width,_allocated_width,list._allocated_width);
      cimg::swap(_data,list._data);
      return list;
    }

    //! Return a reference to an empty list.
    /**
      \note Can be used to define default values in a function taking a CImgList<T> as an argument.
      \code
      void f(const CImgList<char>& list=CImgList<char>::empty());
      \endcode
    **/
    static CImgList<T>& empty() {
      static CImgList<T> _empty;
      return _empty.assign();
    }

    //! Return a reference to an empty list \const.
    static const CImgList<T>& const_empty() {
      static const CImgList<T> _empty;
      return _empty;
    }

    //@}
    //------------------------------------------
    //
    //! \name Overloaded Operators
    //@{
    //------------------------------------------

    //! Return a reference to one image element of the list.
    /**
       \param pos Index of the image element.
    **/
    CImg<T>& operator()(const unsigned int pos) {
#if cimg_verbosity>=3
      if (pos>=_width) {
        cimg::warn(_cimglist_instance
                   "operator(): Invalid image request, at position [%u].",
                   cimglist_instance,
                   pos);
        return *_data;
      }
#endif
      return _data[pos];
    }

    //! Return a reference to one image of the list.
    /**
       \param pos Index of the image element.
    **/
    const CImg<T>& operator()(const unsigned int pos) const {
      return const_cast<CImgList<T>*>(this)->operator()(pos);
    }

    //! Return a reference to one pixel value of one image of the list.
    /**
       \param pos Index of the image element.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list(n,x,y,z,c)</tt> is equivalent to <tt>list[n](x,y,z,c)</tt>.
    **/
    T& operator()(const unsigned int pos, const unsigned int x, const unsigned int y=0,
                  const unsigned int z=0, const unsigned int c=0) {
      return (*this)[pos](x,y,z,c);
    }

    //! Return a reference to one pixel value of one image of the list \const.
    const T& operator()(const unsigned int pos, const unsigned int x, const unsigned int y=0,
                        const unsigned int z=0, const unsigned int c=0) const {
      return (*this)[pos](x,y,z,c);
    }

    //! Return pointer to the first image of the list.
    /**
       \note Images in a list are stored as a buffer of \c CImg<T>.
    **/
    operator CImg<T>*() {
      return _data;
    }

    //! Return pointer to the first image of the list \const.
    operator const CImg<T>*() const {
      return _data;
    }

    //! Construct list from one image \inplace.
    /**
        \param img Input image to copy in the constructed list.
        \note <tt>list = img;</tt> is equivalent to <tt>list.assign(img);</tt>.
    **/
    template<typename t>
    CImgList<T>& operator=(const CImg<t>& img) {
      return assign(img);
    }

    //! Construct list from another list.
    /**
       \param list Input list to copy.
       \note <tt>list1 = list2</tt> is equivalent to <tt>list1.assign(list2);</tt>.
    **/
    template<typename t>
    CImgList<T>& operator=(const CImgList<t>& list) {
      return assign(list);
    }

    //! Construct list from another list \specialization.
    CImgList<T>& operator=(const CImgList<T>& list) {
      return assign(list);
    }

    //! Construct list by reading the content of a file \inplace.
    /**
       \see CImgList(const char *const).
    **/
    CImgList<T>& operator=(const char *const filename) {
      return assign(filename);
    }

    //! Construct list from the content of a display window \inplace.
    /**
        \see CImgList(const CImgDisplay&).
    **/
    CImgList<T>& operator=(const CImgDisplay& disp) {
      return assign(disp);
    }

    //! Return a non-shared copy of a list.
    /**
        \note <tt>+list</tt> is equivalent to <tt>CImgList<T>(list,false)</tt>.
          It forces the copy to have non-shared elements.
    **/
    CImgList<T> operator+() const {
      return CImgList<T>(*this,false);
    }

    //! Return a copy of the list instance, where image \c img has been inserted at the end.
    /**
       \param img Image inserted at the end of the instance copy.
       \note Define a convenient way to create temporary lists of images, as in the following code:
       \code
       (img1,img2,img3,img4).display("My four images");
       \endcode
    **/
    template<typename t>
    CImgList<T>& operator,(const CImg<t>& img) {
      return insert(img);
    }

    //! Return a copy of the list instance, where image \c img has been inserted at the end \const.
    template<typename t>
    CImgList<T> operator,(const CImg<t>& img) const {
      return (+*this).insert(img);
    }

    //! Return a copy of the list instance, where all elements of input list \c list have been inserted at the end.
    /**
       \param list List inserted at the end of the instance copy.
    **/
    template<typename t>
    CImgList<T>& operator,(const CImgList<t>& list) {
      return insert(list);
    }

    //! Return a copy of the list instance, where all elements of input \c list have been inserted at the end \const.
    template<typename t>
    CImgList<T>& operator,(const CImgList<t>& list) const {
      return (+*this).insert(list);
    }

    //! Return the image corresponding to the concatenation of all images of the instance list along specified axis.
    /**
      \param axis Concatenation axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \note <tt>list>'x'</tt> is equivalent to <tt>list.get_append('x')</tt>.
    **/
    CImg<T> operator>(const char axis) const {
      return get_append(axis,0);
    }

    //! Return the list corresponding to the splitting of all images of the instance list along specified axis.
    /**
      \param axis Axis used for image splitting.
      \note <tt>list<'x'</tt> is equivalent to <tt>list.get_split('x')</tt>.
    **/
    CImgList<T> operator<(const char axis) const {
      return get_split(axis);
    }

    //@}
    //-------------------------------------
    //
    //! \name Instance Characteristics
    //@{
    //-------------------------------------

    //! Return the type of image pixel values as a C string.
    /**
       Return a \c char* string containing the usual type name of the image pixel values
       (i.e. a stringified version of the template parameter \c T).
       \note
       - The returned string does not contain any spaces.
       - If the pixel type \c T does not correspond to a registered type, the string <tt>"unknown"</tt> is returned.
    **/
    static const char* pixel_type() {
      return cimg::type<T>::string();
    }

    //! Return the size of the list, i.e. the number of images contained in it.
    /**
      \note Similar to size() but returns the result as a (signed) integer.
    **/
    int width() const {
      return (int)_width;
    }

    //! Return the size of the list, i.e. the number of images contained in it.
    /**
      \note Similar to width() but returns the result as an unsigned integer.
    **/
    unsigned int size() const {
      return _width;
    }

    //! Return pointer to the first image of the list.
    /**
       \note Images in a list are stored as a buffer of \c CImg<T>.
    **/
    CImg<T> *data() {
      return _data;
    }

    //! Return pointer to the first image of the list \const.
    const CImg<T> *data() const {
      return _data;
    }

    //! Return pointer to the pos-th image of the list.
    /**
       \param pos Index of the image element to access.
       \note <tt>list.data(n);</tt> is equivalent to <tt>list.data + n;</tt>.
    **/
#if cimg_verbosity>=3
    CImg<T> *data(const unsigned int pos) {
      if (pos>=size())
        cimg::warn(_cimglist_instance
                   "data(): Invalid pointer request, at position [%u].",
                   cimglist_instance,
                   pos);
      return _data + pos;
    }

    const CImg<T> *data(const unsigned int l) const {
      return const_cast<CImgList<T>*>(this)->data(l);
    }
#else
    CImg<T> *data(const unsigned int l) {
      return _data + l;
    }

    //! Return pointer to the pos-th image of the list \const.
    const CImg<T> *data(const unsigned int l) const {
      return _data + l;
    }
#endif

    //! Return iterator to the first image of the list.
    /**
    **/
    iterator begin() {
      return _data;
    }

    //! Return iterator to the first image of the list \const.
    const_iterator begin() const {
      return _data;
    }

    //! Return iterator to one position after the last image of the list.
    /**
    **/
    iterator end() {
      return _data + _width;
    }

    //! Return iterator to one position after the last image of the list \const.
    const_iterator end() const {
      return _data + _width;
    }

    //! Return reference to the first image of the list.
    /**
    **/
    CImg<T>& front() {
      return *_data;
    }

    //! Return reference to the first image of the list \const.
    const CImg<T>& front() const {
      return *_data;
    }

    //! Return a reference to the last image of the list.
    /**
    **/
    const CImg<T>& back() const {
      return *(_data + _width - 1);
    }

    //! Return a reference to the last image of the list \const.
    CImg<T>& back() {
      return *(_data + _width - 1);
    }

    //! Return pos-th image of the list.
    /**
       \param pos Index of the image element to access.
    **/
    CImg<T>& at(const int pos) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "at(): Empty instance.",
                                    cimglist_instance);

      return _data[cimg::cut(pos,0,width() - 1)];
    }

    //! Access to pixel value with Dirichlet boundary conditions.
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note <tt>list.atNXYZC(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZC(x,y,z,c);</tt>.
    **/
    T& atNXYZC(const int pos, const int x, const int y, const int z, const int c, const T& out_value) {
      return (pos<0 || pos>=width())?(cimg::temporary(out_value)=out_value):_data[pos].atXYZC(x,y,z,c,out_value);
    }

    //! Access to pixel value with Dirichlet boundary conditions \const.
    T atNXYZC(const int pos, const int x, const int y, const int z, const int c, const T& out_value) const {
      return (pos<0 || pos>=width())?out_value:_data[pos].atXYZC(x,y,z,c,out_value);
    }

    //! Access to pixel value with Neumann boundary conditions.
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list.atNXYZC(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZC(x,y,z,c);</tt>.
    **/
    T& atNXYZC(const int pos, const int x, const int y, const int z, const int c) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXYZC(): Empty instance.",
                                    cimglist_instance);

      return _atNXYZC(pos,x,y,z,c);
    }

    //! Access to pixel value with Neumann boundary conditions \const.
    T atNXYZC(const int pos, const int x, const int y, const int z, const int c) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXYZC(): Empty instance.",
                                    cimglist_instance);

      return _atNXYZC(pos,x,y,z,c);
    }

    T& _atNXYZC(const int pos, const int x, const int y, const int z, const int c) {
      return _data[cimg::cut(pos,0,width() - 1)].atXYZC(x,y,z,c);
    }

    T _atNXYZC(const int pos, const int x, const int y, const int z, const int c) const {
      return _data[cimg::cut(pos,0,width() - 1)].atXYZC(x,y,z,c);
    }

    //! Access pixel value with Dirichlet boundary conditions for the 3 coordinates (\c pos, \c x,\c y,\c z).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atNXYZ(const int pos, const int x, const int y, const int z, const int c, const T& out_value) {
      return (pos<0 || pos>=width())?(cimg::temporary(out_value)=out_value):_data[pos].atXYZ(x,y,z,c,out_value);
    }

    //! Access pixel value with Dirichlet boundary conditions for the 3 coordinates (\c pos, \c x,\c y,\c z) \const.
    T atNXYZ(const int pos, const int x, const int y, const int z, const int c, const T& out_value) const {
      return (pos<0 || pos>=width())?out_value:_data[pos].atXYZ(x,y,z,c,out_value);
    }

    //! Access to pixel value with Neumann boundary conditions for the 4 coordinates (\c pos, \c x,\c y,\c z).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
   T& atNXYZ(const int pos, const int x, const int y, const int z, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXYZ(): Empty instance.",
                                    cimglist_instance);

      return _atNXYZ(pos,x,y,z,c);
    }

    //! Access to pixel value with Neumann boundary conditions for the 4 coordinates (\c pos, \c x,\c y,\c z) \const.
    T atNXYZ(const int pos, const int x, const int y, const int z, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXYZ(): Empty instance.",
                                    cimglist_instance);

      return _atNXYZ(pos,x,y,z,c);
    }

    T& _atNXYZ(const int pos, const int x, const int y, const int z, const int c=0) {
      return _data[cimg::cut(pos,0,width() - 1)].atXYZ(x,y,z,c);
    }

    T _atNXYZ(const int pos, const int x, const int y, const int z, const int c=0) const {
      return _data[cimg::cut(pos,0,width() - 1)].atXYZ(x,y,z,c);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the 3 coordinates (\c pos, \c x,\c y).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atNXY(const int pos, const int x, const int y, const int z, const int c, const T& out_value) {
      return (pos<0 || pos>=width())?(cimg::temporary(out_value)=out_value):_data[pos].atXY(x,y,z,c,out_value);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the 3 coordinates (\c pos, \c x,\c y) \const.
    T atNXY(const int pos, const int x, const int y, const int z, const int c, const T& out_value) const {
      return (pos<0 || pos>=width())?out_value:_data[pos].atXY(x,y,z,c,out_value);
    }

    //! Access to pixel value with Neumann boundary conditions for the 3 coordinates (\c pos, \c x,\c y).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atNXY(const int pos, const int x, const int y, const int z=0, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXY(): Empty instance.",
                                    cimglist_instance);

      return _atNXY(pos,x,y,z,c);
    }

    //! Access to pixel value with Neumann boundary conditions for the 3 coordinates (\c pos, \c x,\c y) \const.
    T atNXY(const int pos, const int x, const int y, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNXY(): Empty instance.",
                                    cimglist_instance);

      return _atNXY(pos,x,y,z,c);
    }

    T& _atNXY(const int pos, const int x, const int y, const int z=0, const int c=0) {
      return _data[cimg::cut(pos,0,width() - 1)].atXY(x,y,z,c);
    }

    T _atNXY(const int pos, const int x, const int y, const int z=0, const int c=0) const {
      return _data[cimg::cut(pos,0,width() - 1)].atXY(x,y,z,c);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the 2 coordinates (\c pos,\c x).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atNX(const int pos, const int x, const int y, const int z, const int c, const T& out_value) {
      return (pos<0 || pos>=width())?(cimg::temporary(out_value)=out_value):_data[pos].atX(x,y,z,c,out_value);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the 2 coordinates (\c pos,\c x) \const.
    T atNX(const int pos, const int x, const int y, const int z, const int c, const T& out_value) const {
      return (pos<0 || pos>=width())?out_value:_data[pos].atX(x,y,z,c,out_value);
    }

    //! Access to pixel value with Neumann boundary conditions for the 2 coordinates (\c pos, \c x).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atNX(const int pos, const int x, const int y=0, const int z=0, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNX(): Empty instance.",
                                    cimglist_instance);

      return _atNX(pos,x,y,z,c);
    }

    //! Access to pixel value with Neumann boundary conditions for the 2 coordinates (\c pos, \c x) \const.
    T atNX(const int pos, const int x, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atNX(): Empty instance.",
                                    cimglist_instance);

      return _atNX(pos,x,y,z,c);
    }

    T& _atNX(const int pos, const int x, const int y=0, const int z=0, const int c=0) {
      return _data[cimg::cut(pos,0,width() - 1)].atX(x,y,z,c);
    }

    T _atNX(const int pos, const int x, const int y=0, const int z=0, const int c=0) const {
      return _data[cimg::cut(pos,0,width() - 1)].atX(x,y,z,c);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the coordinate (\c pos).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \param out_value Default value returned if \c offset is outside image bounds.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atN(const int pos, const int x, const int y, const int z, const int c, const T& out_value) {
      return (pos<0 || pos>=width())?(cimg::temporary(out_value)=out_value):(*this)(pos,x,y,z,c);
    }

    //! Access to pixel value with Dirichlet boundary conditions for the coordinate (\c pos) \const.
    T atN(const int pos, const int x, const int y, const int z, const int c, const T& out_value) const {
      return (pos<0 || pos>=width())?out_value:(*this)(pos,x,y,z,c);
    }

    //! Return pixel value with Neumann boundary conditions for the coordinate (\c pos).
    /**
       \param pos Index of the image element to access.
       \param x X-coordinate of the pixel value.
       \param y Y-coordinate of the pixel value.
       \param z Z-coordinate of the pixel value.
       \param c C-coordinate of the pixel value.
       \note <tt>list.atNXYZ(p,x,y,z,c);</tt> is equivalent to <tt>list[p].atXYZ(x,y,z,c);</tt>.
    **/
    T& atN(const int pos, const int x=0, const int y=0, const int z=0, const int c=0) {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atN(): Empty instance.",
                                    cimglist_instance);
      return _atN(pos,x,y,z,c);
    }

    //! Return pixel value with Neumann boundary conditions for the coordinate (\c pos) \const.
    T atN(const int pos, const int x=0, const int y=0, const int z=0, const int c=0) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "atN(): Empty instance.",
                                    cimglist_instance);
      return _atN(pos,x,y,z,c);
    }

    T& _atN(const int pos, const int x=0, const int y=0, const int z=0, const int c=0) {
      return _data[cimg::cut(pos,0,width() - 1)](x,y,z,c);
    }

    T _atN(const int pos, const int x=0, const int y=0, const int z=0, const int c=0) const {
      return _data[cimg::cut(pos,0,width() - 1)](x,y,z,c);
    }

    //@}
    //-------------------------------------
    //
    //! \name Instance Checking
    //@{
    //-------------------------------------

    //! Return \c true if list is empty.
    /**
    **/
    bool is_empty() const {
      return (!_data || !_width);
    }

    //! Test if number of image elements is equal to specified value.
    /**
        \param size_n Number of image elements to test.
    **/
    bool is_sameN(const unsigned int size_n) const {
      return _width==size_n;
    }

    //! Test if number of image elements is equal between two images lists.
    /**
        \param list Input list to compare with.
    **/
    template<typename t>
    bool is_sameN(const CImgList<t>& list) const {
      return is_sameN(list._width);
    }

    // Define useful functions to check list dimensions.
    // (cannot be documented because macro-generated).
#define _cimglist_def_is_same1(axis) \
    bool is_same##axis(const unsigned int val) const { \
      bool res = true; \
      for (unsigned int l = 0; l<_width && res; ++l) res = _data[l].is_same##axis(val); \
      return res; \
    } \
    bool is_sameN##axis(const unsigned int n, const unsigned int val) const { \
      return is_sameN(n) && is_same##axis(val); \
    } \

#define _cimglist_def_is_same2(axis1,axis2) \
    bool is_same##axis1##axis2(const unsigned int val1, const unsigned int val2) const { \
      bool res = true; \
      for (unsigned int l = 0; l<_width && res; ++l) res = _data[l].is_same##axis1##axis2(val1,val2); \
      return res; \
    } \
    bool is_sameN##axis1##axis2(const unsigned int n, const unsigned int val1, const unsigned int val2) const { \
      return is_sameN(n) && is_same##axis1##axis2(val1,val2); \
    } \

#define _cimglist_def_is_same3(axis1,axis2,axis3) \
    bool is_same##axis1##axis2##axis3(const unsigned int val1, const unsigned int val2, \
                                      const unsigned int val3) const { \
      bool res = true; \
      for (unsigned int l = 0; l<_width && res; ++l) res = _data[l].is_same##axis1##axis2##axis3(val1,val2,val3); \
      return res; \
    } \
    bool is_sameN##axis1##axis2##axis3(const unsigned int n, const unsigned int val1, \
                                       const unsigned int val2, const unsigned int val3) const { \
      return is_sameN(n) && is_same##axis1##axis2##axis3(val1,val2,val3); \
    } \

#define _cimglist_def_is_same(axis) \
    template<typename t> bool is_same##axis(const CImg<t>& img) const { \
      bool res = true; \
      for (unsigned int l = 0; l<_width && res; ++l) res = _data[l].is_same##axis(img); \
      return res; \
    } \
    template<typename t> bool is_same##axis(const CImgList<t>& list) const { \
      const unsigned int lmin = std::min(_width,list._width); \
      bool res = true; \
      for (unsigned int l = 0; l<lmin && res; ++l) res = _data[l].is_same##axis(list[l]); \
      return res; \
    } \
    template<typename t> bool is_sameN##axis(const unsigned int n, const CImg<t>& img) const { \
      return (is_sameN(n) && is_same##axis(img)); \
    } \
    template<typename t> bool is_sameN##axis(const CImgList<t>& list) const { \
      return (is_sameN(list) && is_same##axis(list)); \
    }

    _cimglist_def_is_same(XY)
    _cimglist_def_is_same(XZ)
    _cimglist_def_is_same(XC)
    _cimglist_def_is_same(YZ)
    _cimglist_def_is_same(YC)
    _cimglist_def_is_same(XYZ)
    _cimglist_def_is_same(XYC)
    _cimglist_def_is_same(YZC)
    _cimglist_def_is_same(XYZC)
    _cimglist_def_is_same1(X)
    _cimglist_def_is_same1(Y)
    _cimglist_def_is_same1(Z)
    _cimglist_def_is_same1(C)
    _cimglist_def_is_same2(X,Y)
    _cimglist_def_is_same2(X,Z)
    _cimglist_def_is_same2(X,C)
    _cimglist_def_is_same2(Y,Z)
    _cimglist_def_is_same2(Y,C)
    _cimglist_def_is_same2(Z,C)
    _cimglist_def_is_same3(X,Y,Z)
    _cimglist_def_is_same3(X,Y,C)
    _cimglist_def_is_same3(X,Z,C)
    _cimglist_def_is_same3(Y,Z,C)

    //! Test if dimensions of each image of the list match specified arguments.
    /**
      \param dx Checked image width.
      \param dy Checked image height.
      \param dz Checked image depth.
      \param dc Checked image spectrum.
    **/
    bool is_sameXYZC(const unsigned int dx, const unsigned int dy,
                     const unsigned int dz, const unsigned int dc) const {
      bool res = true;
      for (unsigned int l = 0; l<_width && res; ++l) res = _data[l].is_sameXYZC(dx,dy,dz,dc);
      return res;
    }

    //! Test if list dimensions match specified arguments.
    /**
       \param n Number of images in the list.
       \param dx Checked image width.
       \param dy Checked image height.
       \param dz Checked image depth.
       \param dc Checked image spectrum.
    **/
    bool is_sameNXYZC(const unsigned int n,
                      const unsigned int dx, const unsigned int dy,
                      const unsigned int dz, const unsigned int dc) const {
      return is_sameN(n) && is_sameXYZC(dx,dy,dz,dc);
    }

    //! Test if list contains one particular pixel location.
    /**
       \param n Index of the image whom checked pixel value belong to.
       \param x X-coordinate of the checked pixel value.
       \param y Y-coordinate of the checked pixel value.
       \param z Z-coordinate of the checked pixel value.
       \param c C-coordinate of the checked pixel value.
    **/
    bool containsNXYZC(const int n, const int x=0, const int y=0, const int z=0, const int c=0) const {
      if (is_empty()) return false;
      return n>=0 && n<width() && x>=0 && x<_data[n].width() && y>=0 && y<_data[n].height() &&
        z>=0 && z<_data[n].depth() && c>=0 && c<_data[n].spectrum();
    }

    //! Test if list contains image with specified index.
    /**
       \param n Index of the checked image.
    **/
    bool containsN(const int n) const {
      if (is_empty()) return false;
      return n>=0 && n<width();
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
       \param[out] n Index of image containing the pixel value, if test succeeds.
       \param[out] x X-coordinate of the pixel value, if test succeeds.
       \param[out] y Y-coordinate of the pixel value, if test succeeds.
       \param[out] z Z-coordinate of the pixel value, if test succeeds.
       \param[out] c C-coordinate of the pixel value, if test succeeds.
       \note If true, set coordinates (n,x,y,z,c).
    **/
    template<typename t>
    bool contains(const T& pixel, t& n, t& x, t&y, t& z, t& c) const {
      if (is_empty()) return false;
      cimglist_for(*this,l) if (_data[l].contains(pixel,x,y,z,c)) { n = (t)l; return true; }
      return false;
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
       \param[out] n Index of image containing the pixel value, if test succeeds.
       \param[out] x X-coordinate of the pixel value, if test succeeds.
       \param[out] y Y-coordinate of the pixel value, if test succeeds.
       \param[out] z Z-coordinate of the pixel value, if test succeeds.
       \note If true, set coordinates (n,x,y,z).
    **/
    template<typename t>
    bool contains(const T& pixel, t& n, t& x, t&y, t& z) const {
      t c;
      return contains(pixel,n,x,y,z,c);
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
       \param[out] n Index of image containing the pixel value, if test succeeds.
       \param[out] x X-coordinate of the pixel value, if test succeeds.
       \param[out] y Y-coordinate of the pixel value, if test succeeds.
       \note If true, set coordinates (n,x,y).
    **/
    template<typename t>
    bool contains(const T& pixel, t& n, t& x, t&y) const {
      t z, c;
      return contains(pixel,n,x,y,z,c);
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
       \param[out] n Index of image containing the pixel value, if test succeeds.
       \param[out] x X-coordinate of the pixel value, if test succeeds.
       \note If true, set coordinates (n,x).
    **/
    template<typename t>
    bool contains(const T& pixel, t& n, t& x) const {
      t y, z, c;
      return contains(pixel,n,x,y,z,c);
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
       \param[out] n Index of image containing the pixel value, if test succeeds.
       \note If true, set coordinates (n).
    **/
    template<typename t>
    bool contains(const T& pixel, t& n) const {
      t x, y, z, c;
      return contains(pixel,n,x,y,z,c);
    }

    //! Test if one image of the list contains the specified referenced value.
    /**
       \param pixel Reference to pixel value to test.
    **/
    bool contains(const T& pixel) const {
      unsigned int n, x, y, z, c;
      return contains(pixel,n,x,y,z,c);
    }

    //! Test if the list contains the image 'img'.
    /**
       \param img Reference to image to test.
       \param[out] n Index of image in the list, if test succeeds.
       \note If true, returns the position (n) of the image in the list.
    **/
    template<typename t>
    bool contains(const CImg<T>& img, t& n) const {
      if (is_empty()) return false;
      const CImg<T> *const ptr = &img;
      cimglist_for(*this,i) if (_data + i==ptr) { n = (t)i; return true; }
      return false;
    }

    //! Test if the list contains the image img.
    /**
       \param img Reference to image to test.
    **/
    bool contains(const CImg<T>& img) const {
      unsigned int n;
      return contains(img,n);
    }

    //@}
    //-------------------------------------
    //
    //! \name Mathematical Functions
    //@{
    //-------------------------------------

    //! Return a reference to the minimum pixel value of the instance list.
    /**
    **/
    T& min() {
      bool is_all_empty = true;
      T *ptr_min = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_min = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "min(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_min;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) if (*ptrs<min_value) min_value = *(ptr_min=ptrs);
      }
      return *ptr_min;
    }

    //! Return a reference to the minimum pixel value of the instance list \const.
    const T& min() const {
      bool is_all_empty = true;
      T *ptr_min = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_min = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "min(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_min;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) if (*ptrs<min_value) min_value = *(ptr_min=ptrs);
      }
      return *ptr_min;
    }

    //! Return a reference to the maximum pixel value of the instance list.
    /**
    **/
    T& max() {
      bool is_all_empty = true;
      T *ptr_max = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_max = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "max(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T max_value = *ptr_max;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) if (*ptrs>max_value) max_value = *(ptr_max=ptrs);
      }
      return *ptr_max;
    }

    //! Return a reference to the maximum pixel value of the instance list \const.
    const T& max() const {
      bool is_all_empty = true;
      T *ptr_max = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_max = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "max(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T max_value = *ptr_max;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) if (*ptrs>max_value) max_value = *(ptr_max=ptrs);
      }
      return *ptr_max;
    }

    //! Return a reference to the minimum pixel value of the instance list and return the maximum value as well.
    /**
       \param[out] max_val Value of the maximum value found.
    **/
    template<typename t>
    T& min_max(t& max_val) {
      bool is_all_empty = true;
      T *ptr_min = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_min = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "min_max(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_min, max_value = min_value;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) {
          const T val = *ptrs;
          if (val<min_value) { min_value = val; ptr_min = ptrs; }
          if (val>max_value) max_value = val;
        }
      }
      max_val = (t)max_value;
      return *ptr_min;
    }

    //! Return a reference to the minimum pixel value of the instance list and return the maximum value as well \const.
    /**
       \param[out] max_val Value of the maximum value found.
    **/
    template<typename t>
    const T& min_max(t& max_val) const {
      bool is_all_empty = true;
      T *ptr_min = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_min = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "min_max(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_min, max_value = min_value;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) {
          const T val = *ptrs;
          if (val<min_value) { min_value = val; ptr_min = ptrs; }
          if (val>max_value) max_value = val;
        }
      }
      max_val = (t)max_value;
      return *ptr_min;
    }

    //! Return a reference to the maximum pixel value of the instance list and return the minimum value as well.
    /**
       \param[out] min_val Value of the minimum value found.
    **/
    template<typename t>
    T& max_min(t& min_val) {
      bool is_all_empty = true;
      T *ptr_max = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_max = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "max_min(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_max, max_value = min_value;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) {
          const T val = *ptrs;
          if (val>max_value) { max_value = val; ptr_max = ptrs; }
          if (val<min_value) min_value = val;
        }
      }
      min_val = (t)min_value;
      return *ptr_max;
    }

    //! Return a reference to the minimum pixel value of the instance list and return the minimum value as well \const.
    template<typename t>
    const T& max_min(t& min_val) const {
      bool is_all_empty = true;
      T *ptr_max = 0;
      cimglist_for(*this,l) if (!_data[l].is_empty()) {
        ptr_max = _data[l]._data;
        is_all_empty = false;
        break;
      }
      if (is_all_empty)
        throw CImgInstanceException(_cimglist_instance
                                    "max_min(): %s.",
                                    _data?"List of empty images":"Empty instance",
                                    cimglist_instance);
      T min_value = *ptr_max, max_value = min_value;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_for(img,ptrs,T) {
          const T val = *ptrs;
          if (val>max_value) { max_value = val; ptr_max = ptrs; }
          if (val<min_value) min_value = val;
        }
      }
      min_val = (t)min_value;
      return *ptr_max;
    }

    //@}
    //---------------------------
    //
    //! \name List Manipulation
    //@{
    //---------------------------

    //! Insert a copy of the image \c img into the current image list, at position \c pos.
    /**
        \param img Image to insert a copy to the list.
        \param pos Index of the insertion.
        \param is_shared Indicates whether the inserted image is a shared copy of \c img.
    **/
    template<typename t>
    CImgList<T>& insert(const CImg<t>& img, const unsigned int pos=~0U, const bool is_shared=false) {
      const unsigned int npos = pos==~0U?_width:pos;
      if (npos>_width)
        throw CImgArgumentException(_cimglist_instance
                                    "insert(): Invalid request for inserting an image (%u,%u,%u,%u,%p) "
                                    "at position %u.",
                                    cimglist_instance,
                                    img._width,img._height,img._depth,img._spectrum,img._data,npos);
      if (is_shared)
        throw CImgArgumentException(_cimglist_instance
                                    "insert(): Invalid request for inserting a shared image "
                                    "CImg<%s>(%u,%u,%u,%u,%p) at position %u (pixel types are different).",
                                    cimglist_instance,
                                    img.pixel_type(),img._width,img._height,img._depth,img._spectrum,img._data,npos);

      const unsigned int n_allocated_width = _allocated_width?(2*_allocated_width):16;
      CImg<T> *const new_data = (++_width>_allocated_width)?new CImg<T>[n_allocated_width]:0;
      if (new_data) _allocated_width = n_allocated_width;
      if (!_data) { // Insert new element into empty list
        _data = new_data;
        *_data = img;
      } else {
        if (new_data) { // Insert with re-allocation
          if (npos) std::memcpy((void*)new_data,(void*)_data,sizeof(CImg<T>)*npos);
          if (npos!=_width - 1)
            std::memcpy((void*)(new_data + npos + 1),(void*)(_data + npos),sizeof(CImg<T>)*(_width - 1 - npos));
          std::memset((void*)_data,0,sizeof(CImg<T>)*(_width - 1));
          delete[] _data;
          _data = new_data;
        } else if (npos!=_width - 1) // Insert without re-allocation
          std::memmove((void*)(_data + npos + 1),(void*)(_data + npos),sizeof(CImg<T>)*(_width - 1 - npos));
        _data[npos]._width = _data[npos]._height = _data[npos]._depth = _data[npos]._spectrum = 0;
        _data[npos]._data = 0;
        _data[npos] = img;
      }
      return *this;
    }

    //! Insert a copy of the image \c img into the current image list, at position \c pos \specialization.
    CImgList<T>& insert(const CImg<T>& img, const unsigned int pos=~0U, const bool is_shared=false) {
      const unsigned int npos = pos==~0U?_width:pos;
      if (npos>_width)
        throw CImgArgumentException(_cimglist_instance
                                    "insert(): Invalid request for inserting an image (%u,%u,%u,%u,%p) "
                                    "at position %u.",
                                    cimglist_instance,
                                    img._width,img._height,img._depth,img._spectrum,img._data,npos);
      const unsigned int n_allocated_width = _allocated_width?(2*_allocated_width):16;
      CImg<T> *const new_data = (++_width>_allocated_width)?new CImg<T>[n_allocated_width]:0;
      if (new_data) _allocated_width = n_allocated_width;
      if (!_data) { // Insert new element into empty list
        _data = new_data;
        if (is_shared && img) {
          _data->_width = img._width;
          _data->_height = img._height;
          _data->_depth = img._depth;
          _data->_spectrum = img._spectrum;
          _data->_is_shared = true;
          _data->_data = img._data;
        } else *_data = img;
      }
      else {
        if (new_data) { // Insert with re-allocation
          if (npos) std::memcpy((void*)new_data,(void*)_data,sizeof(CImg<T>)*npos);
          if (npos!=_width - 1)
            std::memcpy((void*)(new_data + npos + 1),(void*)(_data + npos),sizeof(CImg<T>)*(_width - 1 - npos));
          if (is_shared && img) {
            new_data[npos]._width = img._width;
            new_data[npos]._height = img._height;
            new_data[npos]._depth = img._depth;
            new_data[npos]._spectrum = img._spectrum;
            new_data[npos]._is_shared = true;
            new_data[npos]._data = img._data;
          } else {
            new_data[npos]._width = new_data[npos]._height = new_data[npos]._depth = new_data[npos]._spectrum = 0;
            new_data[npos]._data = 0;
            new_data[npos] = img;
          }
          std::memset((void*)_data,0,sizeof(CImg<T>)*(_width - 1));
          delete[] _data;
          _data = new_data;
        } else { // Insert without re-allocation
          if (npos!=_width - 1)
            std::memmove((void*)(_data + npos + 1),(void*)(_data + npos),sizeof(CImg<T>)*(_width - 1 - npos));
          if (is_shared && img) {
            _data[npos]._width = img._width;
            _data[npos]._height = img._height;
            _data[npos]._depth = img._depth;
            _data[npos]._spectrum = img._spectrum;
            _data[npos]._is_shared = true;
            _data[npos]._data = img._data;
          } else {
            _data[npos]._width = _data[npos]._height = _data[npos]._depth = _data[npos]._spectrum = 0;
            _data[npos]._data = 0;
            _data[npos] = img;
          }
        }
      }
      return *this;
    }

    //! Insert a copy of the image \c img into the current image list, at position \c pos \newinstance.
    template<typename t>
    CImgList<T> get_insert(const CImg<t>& img, const unsigned int pos=~0U, const bool is_shared=false) const {
      return (+*this).insert(img,pos,is_shared);
    }

    //! Insert n empty images img into the current image list, at position \p pos.
    /**
       \param n Number of empty images to insert.
       \param pos Index of the insertion.
    **/
    CImgList<T>& insert(const unsigned int n, const unsigned int pos=~0U) {
      CImg<T> empty;
      if (!n) return *this;
      const unsigned int npos = pos==~0U?_width:pos;
      for (unsigned int i = 0; i<n; ++i) insert(empty,npos+i);
      return *this;
    }

    //! Insert n empty images img into the current image list, at position \p pos \newinstance.
    CImgList<T> get_insert(const unsigned int n, const unsigned int pos=~0U) const {
      return (+*this).insert(n,pos);
    }

    //! Insert \c n copies of the image \c img into the current image list, at position \c pos.
    /**
       \param n Number of image copies to insert.
       \param img Image to insert by copy.
       \param pos Index of the insertion.
       \param is_shared Indicates whether inserted images are shared copies of \c img.
    **/
    template<typename t>
    CImgList<T>& insert(const unsigned int n, const CImg<t>& img, const unsigned int pos=~0U,
                        const bool is_shared=false) {
      if (!n) return *this;
      const unsigned int npos = pos==~0U?_width:pos;
      insert(img,npos,is_shared);
      for (unsigned int i = 1; i<n; ++i) insert(_data[npos],npos + i,is_shared);
      return *this;
    }

    //! Insert \c n copies of the image \c img into the current image list, at position \c pos \newinstance.
    template<typename t>
    CImgList<T> get_insert(const unsigned int n, const CImg<t>& img, const unsigned int pos=~0U,
                           const bool is_shared=false) const {
      return (+*this).insert(n,img,pos,is_shared);
    }

    //! Insert a copy of the image list \c list into the current image list, starting from position \c pos.
    /**
      \param list Image list to insert.
      \param pos Index of the insertion.
      \param is_shared Indicates whether inserted images are shared copies of images of \c list.
    **/
    template<typename t>
    CImgList<T>& insert(const CImgList<t>& list, const unsigned int pos=~0U, const bool is_shared=false) {
      const unsigned int npos = pos==~0U?_width:pos;
      if ((void*)this!=(void*)&list) cimglist_for(list,l) insert(list[l],npos + l,is_shared);
      else insert(CImgList<T>(list),npos,is_shared);
      return *this;
    }

    //! Insert a copy of the image list \c list into the current image list, starting from position \c pos \newinstance.
    template<typename t>
    CImgList<T> get_insert(const CImgList<t>& list, const unsigned int pos=~0U, const bool is_shared=false) const {
      return (+*this).insert(list,pos,is_shared);
    }

    //! Insert n copies of the list \c list at position \c pos of the current list.
    /**
      \param n Number of list copies to insert.
      \param list Image list to insert.
      \param pos Index of the insertion.
      \param is_shared Indicates whether inserted images are shared copies of images of \c list.
    **/
    template<typename t>
    CImgList<T>& insert(const unsigned int n, const CImgList<t>& list, const unsigned int pos=~0U,
                        const bool is_shared=false) {
      if (!n) return *this;
      const unsigned int npos = pos==~0U?_width:pos;
      for (unsigned int i = 0; i<n; ++i) insert(list,npos,is_shared);
      return *this;
    }

    //! Insert n copies of the list \c list at position \c pos of the current list \newinstance.
    template<typename t>
    CImgList<T> get_insert(const unsigned int n, const CImgList<t>& list, const unsigned int pos=~0U,
                           const bool is_shared=false) const {
      return (+*this).insert(n,list,pos,is_shared);
    }

    //! Remove all images between from indexes.
    /**
      \param pos1 Starting index of the removal.
      \param pos2 Ending index of the removal.
    **/
    CImgList<T>& remove(const unsigned int pos1, const unsigned int pos2) {
      const unsigned int
        npos1 = pos1<pos2?pos1:pos2,
        tpos2 = pos1<pos2?pos2:pos1,
        npos2 = tpos2<_width?tpos2:_width - 1;
      if (npos1>=_width)
        throw CImgArgumentException(_cimglist_instance
                                    "remove(): Invalid remove request at positions %u->%u.",
                                    cimglist_instance,
                                    npos1,tpos2);
      else {
        if (tpos2>=_width)
          throw CImgArgumentException(_cimglist_instance
                                      "remove(): Invalid remove request at positions %u->%u.",
                                      cimglist_instance,
                                      npos1,tpos2);

        for (unsigned int k = npos1; k<=npos2; ++k) _data[k].assign();
        const unsigned int nb = 1 + npos2 - npos1;
        if (!(_width-=nb)) return assign();
        if (_width>(_allocated_width>>4) || _allocated_width<=16) { // Removing items without reallocation
          if (npos1!=_width)
            std::memmove((void*)(_data + npos1),(void*)(_data + npos2 + 1),sizeof(CImg<T>)*(_width - npos1));
          std::memset((void*)(_data + _width),0,sizeof(CImg<T>)*nb);
        } else { // Removing items with reallocation
          _allocated_width>>=4;
          while (_allocated_width>16 && _width<(_allocated_width>>1)) _allocated_width>>=1;
          CImg<T> *const new_data = new CImg<T>[_allocated_width];
          if (npos1) std::memcpy((void*)new_data,(void*)_data,sizeof(CImg<T>)*npos1);
          if (npos1!=_width)
            std::memcpy((void*)(new_data + npos1),(void*)(_data + npos2 + 1),sizeof(CImg<T>)*(_width - npos1));
          if (_width!=_allocated_width)
            std::memset((void*)(new_data + _width),0,sizeof(CImg<T>)*(_allocated_width - _width));
          std::memset((void*)_data,0,sizeof(CImg<T>)*(_width + nb));
          delete[] _data;
          _data = new_data;
        }
      }
      return *this;
    }

    //! Remove all images between from indexes \newinstance.
    CImgList<T> get_remove(const unsigned int pos1, const unsigned int pos2) const {
      return (+*this).remove(pos1,pos2);
    }

    //! Remove image at index \c pos from the image list.
    /**
      \param pos Index of the image to remove.
    **/
    CImgList<T>& remove(const unsigned int pos) {
      return remove(pos,pos);
    }

    //! Remove image at index \c pos from the image list \newinstance.
    CImgList<T> get_remove(const unsigned int pos) const {
      return (+*this).remove(pos);
    }

    //! Remove last image.
    /**
    **/
    CImgList<T>& remove() {
      return remove(_width - 1);
    }

    //! Remove last image \newinstance.
    CImgList<T> get_remove() const {
      return (+*this).remove();
    }

    //! Reverse list order.
    CImgList<T>& reverse() {
      for (unsigned int l = 0; l<_width/2; ++l) (*this)[l].swap((*this)[_width - 1 - l]);
      return *this;
    }

    //! Reverse list order \newinstance.
    CImgList<T> get_reverse() const {
      return (+*this).reverse();
    }

    //! Return a sublist.
    /**
      \param pos0 Starting index of the sublist.
      \param pos1 Ending index of the sublist.
    **/
    CImgList<T>& images(const unsigned int pos0, const unsigned int pos1) {
      return get_images(pos0,pos1).move_to(*this);
    }

    //! Return a sublist \newinstance.
    CImgList<T> get_images(const unsigned int pos0, const unsigned int pos1) const {
      if (pos0>pos1 || pos1>=_width)
        throw CImgArgumentException(_cimglist_instance
                                    "images(): Specified sub-list indices (%u->%u) are out of bounds.",
                                    cimglist_instance,
                                    pos0,pos1);
      CImgList<T> res(pos1 - pos0 + 1);
      cimglist_for(res,l) res[l].assign(_data[pos0 + l]);
      return res;
    }

    //! Return a shared sublist.
    /**
      \param pos0 Starting index of the sublist.
      \param pos1 Ending index of the sublist.
    **/
    CImgList<T> get_shared_images(const unsigned int pos0, const unsigned int pos1) {
      if (pos0>pos1 || pos1>=_width)
        throw CImgArgumentException(_cimglist_instance
                                    "get_shared_images(): Specified sub-list indices (%u->%u) are out of bounds.",
                                    cimglist_instance,
                                    pos0,pos1);
      CImgList<T> res(pos1 - pos0 + 1);
      cimglist_for(res,l) res[l].assign(_data[pos0 + l],_data[pos0 + l]?true:false);
      return res;
    }

    //! Return a shared sublist \newinstance.
    const CImgList<T> get_shared_images(const unsigned int pos0, const unsigned int pos1) const {
      if (pos0>pos1 || pos1>=_width)
        throw CImgArgumentException(_cimglist_instance
                                    "get_shared_images(): Specified sub-list indices (%u->%u) are out of bounds.",
                                    cimglist_instance,
                                    pos0,pos1);
      CImgList<T> res(pos1 - pos0 + 1);
      cimglist_for(res,l) res[l].assign(_data[pos0 + l],_data[pos0 + l]?true:false);
      return res;
    }

    //! Return a single image which is the concatenation of all images of the current CImgList instance.
    /**
       \param axis Concatenation axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param align Concatenation alignment.
    **/
    CImg<T> get_append(const char axis, const float align=0) const {
      if (is_empty()) return CImg<T>();
      if (_width==1) return +_data[0];
      if (_width==2) return _data[0].get_append(_data[1],axis,align);

      unsigned int dx = 0, dy = 0, dz = 0, dc = 0, pos = 0;
      CImg<T> res;
      switch (cimg::lowercase(axis)) {
      case 'x' : { // Along the X-axis
        cimglist_for(*this,l) {
          const CImg<T>& img = (*this)[l];
          if (img) {
            dx+=img._width;
            dy = std::max(dy,img._height);
            dz = std::max(dz,img._depth);
            dc = std::max(dc,img._spectrum);
          }
        }
        res.assign(dx,dy,dz,dc,(T)0);
        if (res) cimglist_for(*this,l) {
            const CImg<T>& img = (*this)[l];
            if (img) {
              if (img._height==1 && img._depth==1 && img._spectrum==1 &&
                  res._height==1 && res._depth==1 && res._spectrum==1)
                std::memcpy(&res[pos],img._data,sizeof(T)*img._width);
              else
                res.draw_image(pos,
                               (int)(align*(dy - img._height)),
                               (int)(align*(dz - img._depth)),
                               (int)(align*(dc - img._spectrum)),
                               img);
            }
            pos+=img._width;
          }
      } break;
      case 'y' : { // Along the Y-axis
        cimglist_for(*this,l) {
          const CImg<T>& img = (*this)[l];
          if (img) {
            dx = std::max(dx,img._width);
            dy+=img._height;
            dz = std::max(dz,img._depth);
            dc = std::max(dc,img._spectrum);
          }
        }
        res.assign(dx,dy,dz,dc,(T)0);
        if (res) cimglist_for(*this,l) {
            const CImg<T>& img = (*this)[l];
            if (img) {
              if (img._width==1 && img._depth==1 && img._spectrum==1 &&
                  res._width==1 && res._depth==1 && res._spectrum==1)
                std::memcpy(&res[pos],img._data,sizeof(T)*img._height);
              else
                res.draw_image((int)(align*(dx - img._width)),
                               pos,
                               (int)(align*(dz - img._depth)),
                               (int)(align*(dc - img._spectrum)),
                               img);
            }
            pos+=img._height;
          }
      } break;
      case 'z' : { // Along the Z-axis
        cimglist_for(*this,l) {
          const CImg<T>& img = (*this)[l];
          if (img) {
            dx = std::max(dx,img._width);
            dy = std::max(dy,img._height);
            dz+=img._depth;
            dc = std::max(dc,img._spectrum);
          }
        }
        res.assign(dx,dy,dz,dc,(T)0);
        if (res) cimglist_for(*this,l) {
            const CImg<T>& img = (*this)[l];
            if (img) {
              if (img._width==1 && img._height==1 && img._spectrum==1 &&
                  res._width==1 && res._height==1 && res._spectrum==1)
                std::memcpy(&res[pos],img._data,sizeof(T)*img._depth);
              else
                res.draw_image((int)(align*(dx - img._width)),
                               (int)(align*(dy - img._height)),
                               pos,
                               (int)(align*(dc - img._spectrum)),
                               img);
            }
            pos+=img._depth;
          }
      } break;
      default : { // Along the C-axis
        cimglist_for(*this,l) {
          const CImg<T>& img = (*this)[l];
          if (img) {
            dx = std::max(dx,img._width);
            dy = std::max(dy,img._height);
            dz = std::max(dz,img._depth);
            dc+=img._spectrum;
          }
        }
        res.assign(dx,dy,dz,dc,(T)0);
        if (res) cimglist_for(*this,l) {
            const CImg<T>& img = (*this)[l];
            if (img) {
              if (img._width==1 && img._height==1 && img._depth==1 &&
                  res._width==1 && res._height==1 && res._depth==1)
                std::memcpy(&res[pos],img._data,sizeof(T)*img._spectrum);
              else
                res.draw_image((int)(align*(dx - img._width)),
                               (int)(align*(dy - img._height)),
                               (int)(align*(dz - img._depth)),
                               pos,
                               img);
            }
            pos+=img._spectrum;
          }
      }
      }
      return res;
    }

    //! Return a list where each image has been split along the specified axis.
    /**
        \param axis Axis to split images along.
        \param nb Number of split parts for each image.
    **/
    CImgList<T>& split(const char axis, const int nb=-1) {
      return get_split(axis,nb).move_to(*this);
    }

    //! Return a list where each image has been split along the specified axis \newinstance.
    CImgList<T> get_split(const char axis, const int nb=-1, const unsigned int max_parts=~0U) const {
      CImgList<T> res;
      cimglist_for(*this,l) _data[l].get_split(axis,nb,max_parts).move_to(res,~0U);
      return res;
    }

    //! Insert image at the end of the list.
    /**
      \param img Image to insert.
    **/
    template<typename t>
    CImgList<T>& push_back(const CImg<t>& img) {
      return insert(img);
    }

    //! Insert image at the front of the list.
    /**
      \param img Image to insert.
    **/
    template<typename t>
    CImgList<T>& push_front(const CImg<t>& img) {
      return insert(img,0);
    }

    //! Insert list at the end of the current list.
    /**
      \param list List to insert.
    **/
    template<typename t>
    CImgList<T>& push_back(const CImgList<t>& list) {
      return insert(list);
    }

    //! Insert list at the front of the current list.
    /**
      \param list List to insert.
    **/
    template<typename t>
    CImgList<T>& push_front(const CImgList<t>& list) {
      return insert(list,0);
    }

    //! Remove last image.
    /**
    **/
    CImgList<T>& pop_back() {
      return remove(_width - 1);
    }

    //! Remove first image.
    /**
    **/
    CImgList<T>& pop_front() {
      return remove(0);
    }

    //! Remove image pointed by iterator.
    /**
      \param iter Iterator pointing to the image to remove.
    **/
    CImgList<T>& erase(const iterator iter) {
      return remove(iter - _data);
    }

    //@}
    //----------------------------------
    //
    //! \name Data Input
    //@{
    //----------------------------------

    //! Display a simple interactive interface to select images or sublists.
    /**
       \param disp Window instance to display selection and user interface.
       \param feature_type Can be \c false to select a single image, or \c true to select a sublist.
       \param axis Axis along whom images are appended for visualization.
       \param align Alignment setting when images have not all the same size.
       \param exit_on_anykey Exit function when any key is pressed.
       \return A one-column vector containing the selected image indexes.
    **/
    CImg<intT> get_select(CImgDisplay &disp, const bool feature_type=true,
                          const char axis='x', const float align=0,
                          const bool exit_on_anykey=false) const {
      return _select(disp,0,feature_type,axis,align,exit_on_anykey,0,false,false,false);
    }

    //! Display a simple interactive interface to select images or sublists.
    /**
       \param title Title of a new window used to display selection and user interface.
       \param feature_type Can be \c false to select a single image, or \c true to select a sublist.
       \param axis Axis along whom images are appended for visualization.
       \param align Alignment setting when images have not all the same size.
       \param exit_on_anykey Exit function when any key is pressed.
       \return A one-column vector containing the selected image indexes.
    **/
    CImg<intT> get_select(const char *const title, const bool feature_type=true,
                          const char axis='x', const float align=0,
                          const bool exit_on_anykey=false) const {
      CImgDisplay disp;
      return _select(disp,title,feature_type,axis,align,exit_on_anykey,0,false,false,false);
    }

    CImg<intT> _select(CImgDisplay &disp, const char *const title, const bool feature_type,
                       const char axis, const float align, const bool exit_on_anykey,
                       const unsigned int orig, const bool resize_disp,
                       const bool exit_on_rightbutton, const bool exit_on_wheel) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "select(): Empty instance.",
                                    cimglist_instance);

      // Create image correspondence table and get list dimensions for visualization.
      CImgList<uintT> _indices;
      unsigned int max_width = 0, max_height = 0, sum_width = 0, sum_height = 0;
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        const unsigned int
          w = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,false),
          h = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,true);
        if (w>max_width) max_width = w;
        if (h>max_height) max_height = h;
        sum_width+=w; sum_height+=h;
        if (axis=='x') CImg<uintT>(w,1,1,1,(unsigned int)l).move_to(_indices);
        else CImg<uintT>(h,1,1,1,(unsigned int)l).move_to(_indices);
      }
      const CImg<uintT> indices0 = _indices>'x';

      // Create display window.
      if (!disp) {
        if (axis=='x') disp.assign(cimg_fitscreen(sum_width,max_height,1),title?title:0,1);
        else disp.assign(cimg_fitscreen(max_width,sum_height,1),title?title:0,1);
        if (!title) disp.set_title("CImgList<%s> (%u)",pixel_type(),_width);
      } else {
        if (title) disp.set_title("%s",title);
        disp.move_inside_screen();
      }
      if (resize_disp) {
        if (axis=='x') disp.resize(cimg_fitscreen(sum_width,max_height,1),false);
        else disp.resize(cimg_fitscreen(max_width,sum_height,1),false);
      }

      const unsigned int old_normalization = disp.normalization();
      bool old_is_resized = disp.is_resized();
      disp._normalization = 0;
      disp.show().set_key(0).show_mouse();
      static const unsigned char foreground_color[] = { 255,255,255 }, background_color[] = { 0,0,0 };

      // Enter event loop.
      CImg<ucharT> visu0, visu;
      CImg<uintT> indices;
      CImg<intT> positions(_width,4,1,1,-1);
      int oindex0 = -1, oindex1 = -1, index0 = -1, index1 = -1;
      bool is_clicked = false, is_selected = false, text_down = false, update_display = true;
      unsigned int key = 0, font_size = 32;

      while (!is_selected && !disp.is_closed() && !key) {

        // Create background image.
        if (!visu0) {
          visu0.assign(disp._width,disp._height,1,3,0); visu.assign();
          (indices0.get_resize(axis=='x'?visu0._width:visu0._height,1)).move_to(indices);
          unsigned int _ind = 0;
          const CImg<T> onexone(1,1,1,1,(T)0);
          if (axis=='x')
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(_width,4))
            cimglist_for(*this,ind) {
              unsigned int x0 = 0;
              while (x0<visu0._width && indices[x0++]!=(unsigned int)ind) {}
              unsigned int x1 = x0;
              while (x1<visu0._width && indices[x1++]==(unsigned int)ind) {}
              const CImg<T> &src = _data[ind]?_data[ind]:onexone;
              CImg<ucharT> res;
              src._get_select(disp,old_normalization,src._width/2,src._height/2,src._depth/2).
                move_to(res);
              const unsigned int h = CImgDisplay::_fitscreen(res._width,res._height,1,128,-85,true);
              res.resize(x1 - x0,std::max(32U,h*disp._height/max_height),1,res._spectrum==1?3:-100);
              positions(ind,0) = positions(ind,2) = (int)x0;
              positions(ind,1) = positions(ind,3) = (int)(align*(visu0.height() - res.height()));
              positions(ind,2)+=res._width;
              positions(ind,3)+=res._height - 1;
              visu0.draw_image(positions(ind,0),positions(ind,1),res);
            }
          else
            cimg_pragma_openmp(parallel for cimg_openmp_if_size(_width,4))
            cimglist_for(*this,ind) {
              unsigned int y0 = 0;
              while (y0<visu0._height && indices[y0++]!=(unsigned int)ind) {}
              unsigned int y1 = y0;
              while (y1<visu0._height && indices[y1++]==(unsigned int)ind) {}
              const CImg<T> &src = _data[ind]?_data[ind]:onexone;
              CImg<ucharT> res;
              src._get_select(disp,old_normalization,(src._width - 1)/2,(src._height - 1)/2,(src._depth - 1)/2).
                move_to(res);
              const unsigned int w = CImgDisplay::_fitscreen(res._width,res._height,1,128,-85,false);
              res.resize(std::max(32U,w*disp._width/max_width),y1 - y0,1,res._spectrum==1?3:-100);
              positions(ind,0) = positions(ind,2) = (int)(align*(visu0.width() - res.width()));
              positions(ind,1) = positions(ind,3) = (int)y0;
              positions(ind,2)+=res._width - 1;
              positions(ind,3)+=res._height;
              visu0.draw_image(positions(ind,0),positions(ind,1),res);
            }
          if (axis=='x') --positions(_ind,2); else --positions(_ind,3);
          update_display = true;
        }

        if (!visu || oindex0!=index0 || oindex1!=index1) {
          if (index0>=0 && index1>=0) {
            visu.assign(visu0,false);
            const int indm = std::min(index0,index1), indM = std::max(index0,index1);
            for (int ind = indm; ind<=indM; ++ind) if (positions(ind,0)>=0) {
                visu.draw_rectangle(positions(ind,0),positions(ind,1),positions(ind,2),positions(ind,3),
                                    background_color,0.2f);
                if ((axis=='x' && positions(ind,2) - positions(ind,0)>=8) ||
                    (axis!='x' && positions(ind,3) - positions(ind,1)>=8))
                  visu.draw_rectangle(positions(ind,0),positions(ind,1),positions(ind,2),positions(ind,3),
                                      foreground_color,0.9f,0xAAAAAAAA);
              }
            if (is_clicked) visu.__draw_text(" Images #%u - #%u, Size = %u ",font_size,(int)text_down,
                                             orig + indm,orig + indM,indM - indm + 1);
            else visu.__draw_text(" Image #%u (%u,%u,%u,%u) ",font_size,(int)text_down,
                                  orig + index0,
                                  _data[index0]._width,
                                  _data[index0]._height,
                                  _data[index0]._depth,
                                  _data[index0]._spectrum);
            update_display = true;
          } else visu.assign();
        }
        if (!visu) { visu.assign(visu0,true); update_display = true; }
        if (update_display) { visu.display(disp); update_display = false; }
        disp.wait();

        // Manage user events.
        const int xm = disp.mouse_x(), ym = disp.mouse_y();
        int index = -1;

        if (xm>=0) {
          index = (int)indices(axis=='x'?xm:ym);
          if (disp.button()&1) {
            if (!is_clicked) { is_clicked = true; oindex0 = index0; index0 = index; }
            oindex1 = index1; index1 = index;
            if (!feature_type) is_selected = true;
          } else {
            if (!is_clicked) { oindex0 = oindex1 = index0; index0 = index1 = index; }
            else is_selected = true;
          }
        } else {
          if (is_clicked) {
            if (!(disp.button()&1)) { is_clicked = is_selected = false; index0 = index1 = -1; }
            else index1 = -1;
          } else index0 = index1 = -1;
        }

        if (disp.button()&4) { is_clicked = is_selected = false; index0 = index1 = -1; }
        if (disp.button()&2 && exit_on_rightbutton) { is_selected = true; index1 = index0 = -1; }
        if (disp.wheel() && exit_on_wheel) is_selected = true;

        CImg<charT> filename(1024);
        switch (key = disp.key()) {
#if cimg_OS!=2
        case cimg::keyCTRLRIGHT :
#endif
        case 0 : case cimg::keyCTRLLEFT : key = 0; break;
        case cimg::keyD : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                     CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false).
              _is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false)._is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(axis=='x'?sum_width:max_width,axis=='x'?max_height:sum_height,1),false).
              _is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.resize(disp.screen_width(),disp.screen_height(),false).toggle_fullscreen()._is_resized = true;
            disp.set_key(key,false); key = 0; visu0.assign();
          } break;
        case cimg::keyS : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u."
#ifdef cimg_use_png
                            "png",
#else
                            "bmp",
#endif
                            snap_number++);
            } while (cimg::path_exists(filename));
            if (visu0) {
              (+visu0).__draw_text(" Saving snapshot... ",font_size,(int)text_down).display(disp);
              visu0.save(filename);
              (+visu0).__draw_text(" Snapshot '%s' saved. ",font_size,(int)text_down,filename._data).display(disp);
            }
            disp.set_key(key,false).wait(); key = 0;
          } break;
        case cimg::keyO :
          if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            static unsigned int snap_number = 0;
            do {
#ifdef cimg_use_zlib
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimgz",snap_number++);
#else
              cimg_snprintf(filename,filename._width,cimg_appname "_%.6u.cimg",snap_number++);
#endif
            } while (cimg::path_exists(filename));
            (+visu0).__draw_text(" Saving instance... ",font_size,(int)text_down).display(disp);
            save(filename);
            (+visu0).__draw_text(" Instance '%s' saved. ",font_size,(int)text_down,filename._data).display(disp);
            disp.set_key(key,false).wait(); key = 0;
          } break;
        }
        if (disp.is_resized()) { disp.resize(false); visu0.assign(); }
        if (ym>=0 && ym<13) { if (!text_down) { visu.assign(); text_down = true; }}
        else if (ym>=visu.height() - 13) { if (text_down) { visu.assign(); text_down = false; }}
        if (!exit_on_anykey && key && key!=cimg::keyESC &&
            (key!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          key = 0;
        }
      }
      CImg<intT> res(1,2,1,1,-1);
      if (is_selected) {
        if (feature_type) res.fill(std::min(index0,index1),std::max(index0,index1));
        else res.fill(index0);
      }
      if (!(disp.button()&2)) disp.set_button();
      disp._normalization = old_normalization;
      disp._is_resized = old_is_resized;
      disp.set_key(key);
      return res;
    }

    //! Load a list from a file.
    /**
     \param filename Filename to read data from.
    **/
    CImgList<T>& load(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimglist_instance
                                    "load(): Specified filename is (null).",
                                    cimglist_instance);

      if (!cimg::strncasecmp(filename,"http://",7) || !cimg::strncasecmp(filename,"https://",8)) {
        CImg<charT> filename_local(256);
        load(cimg::load_network(filename,filename_local));
        std::remove(filename_local);
        return *this;
      }

      const bool is_stdin = *filename=='-' && (!filename[1] || filename[1]=='.');
      const char *const ext = cimg::split_filename(filename);
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      bool is_loaded = true;
      try {
#ifdef cimglist_load_plugin
        cimglist_load_plugin(filename);
#endif
#ifdef cimglist_load_plugin1
        cimglist_load_plugin1(filename);
#endif
#ifdef cimglist_load_plugin2
        cimglist_load_plugin2(filename);
#endif
#ifdef cimglist_load_plugin3
        cimglist_load_plugin3(filename);
#endif
#ifdef cimglist_load_plugin4
        cimglist_load_plugin4(filename);
#endif
#ifdef cimglist_load_plugin5
        cimglist_load_plugin5(filename);
#endif
#ifdef cimglist_load_plugin6
        cimglist_load_plugin6(filename);
#endif
#ifdef cimglist_load_plugin7
        cimglist_load_plugin7(filename);
#endif
#ifdef cimglist_load_plugin8
        cimglist_load_plugin8(filename);
#endif
        if (!cimg::strcasecmp(ext,"tif") ||
            !cimg::strcasecmp(ext,"tiff")) load_tiff(filename);
        else if (!cimg::strcasecmp(ext,"gif")) load_gif_external(filename);
        else if (!cimg::strcasecmp(ext,"cimg") ||
                 !cimg::strcasecmp(ext,"cimgz") ||
                 !*ext) load_cimg(filename);
        else if (!cimg::strcasecmp(ext,"rec") ||
                 !cimg::strcasecmp(ext,"par")) load_parrec(filename);
        else if (!cimg::strcasecmp(ext,"avi") ||
                 !cimg::strcasecmp(ext,"mov") ||
                 !cimg::strcasecmp(ext,"asf") ||
                 !cimg::strcasecmp(ext,"divx") ||
                 !cimg::strcasecmp(ext,"flv") ||
                 !cimg::strcasecmp(ext,"mpg") ||
                 !cimg::strcasecmp(ext,"m1v") ||
                 !cimg::strcasecmp(ext,"m2v") ||
                 !cimg::strcasecmp(ext,"m4v") ||
                 !cimg::strcasecmp(ext,"mjp") ||
                 !cimg::strcasecmp(ext,"mp4") ||
                 !cimg::strcasecmp(ext,"mkv") ||
                 !cimg::strcasecmp(ext,"mpe") ||
                 !cimg::strcasecmp(ext,"movie") ||
                 !cimg::strcasecmp(ext,"ogm") ||
                 !cimg::strcasecmp(ext,"ogg") ||
                 !cimg::strcasecmp(ext,"ogv") ||
                 !cimg::strcasecmp(ext,"qt") ||
                 !cimg::strcasecmp(ext,"rm") ||
                 !cimg::strcasecmp(ext,"vob") ||
                 !cimg::strcasecmp(ext,"webm") ||
                 !cimg::strcasecmp(ext,"wmv") ||
                 !cimg::strcasecmp(ext,"xvid") ||
                 !cimg::strcasecmp(ext,"mpeg")) load_video(filename);
        else if (!cimg::strcasecmp(ext,"gz")) load_gzip_external(filename);
        else is_loaded = false;
      } catch (CImgIOException&) { is_loaded = false; }

      // If nothing loaded, try to guess file format from magic number in file.
      if (!is_loaded && !is_stdin) {
        std::FILE *const file = cimg::std_fopen(filename,"rb");
        if (!file) {
          cimg::exception_mode(omode);
          throw CImgIOException(_cimglist_instance
                                "load(): Failed to open file '%s'.",
                                cimglist_instance,
                                filename);
        }

        const char *const f_type = cimg::ftype(file,filename);
        cimg::fclose(file);
        is_loaded = true;
        try {
          if (!cimg::strcasecmp(f_type,"gif")) load_gif_external(filename);
          else if (!cimg::strcasecmp(f_type,"tif") &&
                   cimg::strcasecmp(ext,"nef") &&
                   cimg::strcasecmp(ext,"dng")) load_tiff(filename);
          else is_loaded = false;
        } catch (CImgIOException&) { is_loaded = false; }
      }

      // If nothing loaded, try to load file as a single image.
      if (!is_loaded) {
        assign(1);
        try {
          _data->load(filename);
        } catch (CImgIOException&) {
          cimg::exception_mode(omode);
          throw CImgIOException(_cimglist_instance
                                "load(): Failed to recognize format of file '%s'.",
                                cimglist_instance,
                                filename);
        }
      }
      cimg::exception_mode(omode);
      return *this;
    }

    //! Load a list from a file \newinstance.
    static CImgList<T> get_load(const char *const filename) {
      return CImgList<T>().load(filename);
    }

    //! Load a list from a .cimg file.
    /**
      \param filename Filename to read data from.
    **/
    CImgList<T>& load_cimg(const char *const filename) {
      return _load_cimg(0,filename);
    }

    //! Load a list from a .cimg file \newinstance.
    static CImgList<T> get_load_cimg(const char *const filename) {
      return CImgList<T>().load_cimg(filename);
    }

    //! Load a list from a .cimg file.
    /**
      \param file File to read data from.
    **/
    CImgList<T>& load_cimg(std::FILE *const file) {
      return _load_cimg(file,0);
    }

    //! Load a list from a .cimg file \newinstance.
    static CImgList<T> get_load_cimg(std::FILE *const file) {
      return CImgList<T>().load_cimg(file);
    }

    CImgList<T>& _load_cimg(std::FILE *const file, const char *const filename) {
#ifdef cimg_use_zlib
#define _cimgz_load_cimg_case(Tss) { \
   Bytef *const cbuf = new Bytef[csiz]; \
   cimg::fread(cbuf,(size_t)csiz,nfile); \
   if (is_bool) { \
     CImg<ucharT> raw(W*H*D*C/8); \
     uLongf destlen = (uLongf)raw.size(); \
     uncompress((Bytef*)raw._data,&destlen,cbuf,(uLong)csiz); \
     img.assign(W,H,D,C); \
     img._uchar2bool(raw,raw.size(),false); \
   } else { \
     CImg<Tss> raw(W,H,D,C); \
     uLongf destlen = (uLongf)(raw.size()*sizeof(Tss)); \
     uncompress((Bytef*)raw._data,&destlen,cbuf,(uLong)csiz); \
     if (endian!=cimg::endianness()) cimg::invert_endianness(raw._data,raw.size()); \
     raw.move_to(img); \
   } \
   delete[] cbuf; \
}
#else
#define _cimgz_load_cimg_case(Tss) \
   throw CImgIOException(_cimglist_instance \
                         "load_cimg(): Unable to load compressed data from file '%s' unless zlib is enabled.", \
                         cimglist_instance, \
                         filename?filename:"(FILE*)");
#endif

#define _cimg_load_cimg_case(Ts1,Ts2,Ts3,Tss) \
      if (!loaded && ((Ts1 && !cimg::strcasecmp(Ts1,str_pixeltype)) || \
                      (Ts2 && !cimg::strcasecmp(Ts2,str_pixeltype)) || \
                      (Ts3 && !cimg::strcasecmp(Ts3,str_pixeltype)))) { \
        const bool is_bool = cimg::type<Tss>::string()==cimg::type<bool>::string(); \
        for (int l = 0; l<N; ++l) { \
          j = 0; while ((i=std::fgetc(nfile))!='\n' && i>=0 && j<255) tmp[j++] = (char)i; tmp[j] = 0; \
          W = H = D = C = 0; csiz = 0; \
          if ((err = cimg_sscanf(tmp._data,"%d %d %d %d #" cimg_fuint64,&W,&H,&D,&C,&csiz))<4 || \
              W<0 || H<0 || D<0 || C<0) \
            throw CImgIOException(_cimglist_instance \
                                  "load_cimg(): Invalid specified size (%d,%d,%d,%d) of image %u in file '%s'.", \
                                  cimglist_instance, \
                                  W,H,D,C,l,filename?filename:("(FILE*)")); \
          if (W*H*D*C>0) { \
            CImg<T> &img = _data[l]; \
            if (err==5) _cimgz_load_cimg_case(Tss) \
            else { \
              img.assign(W,H,D,C); \
              T *ptrd = img._data; \
              if (is_bool) { \
                CImg<ucharT> raw; \
                for (ulongT to_read = img.size(); to_read; ) { \
                  raw.assign((unsigned int)std::min(to_read,cimg_iobuffer)); \
                  cimg::fread(raw._data,raw._width,nfile); \
                  CImg<T>(ptrd,std::min(8*raw._width,(unsigned int)(img.end() - ptrd)),1,1,1,true).\
                    _uchar2bool(raw,raw._width,false); \
                  to_read-=raw._width; \
                } \
              } else { \
                CImg<Tss> raw; \
                for (ulongT to_read = img.size(); to_read; ) { \
                  raw.assign((unsigned int)std::min(to_read,cimg_iobuffer)); \
                  cimg::fread(raw._data,raw._width,nfile); \
                  if (endian!=cimg::endianness()) cimg::invert_endianness(raw._data,raw.size()); \
                  const Tss *ptrs = raw._data; \
                  for (ulongT off = (ulongT)raw._width; off; --off) *(ptrd++) = (T)*(ptrs++); \
                  to_read-=raw._width; \
                } \
              } \
            } \
          } \
        } \
        loaded = true; \
      }

      if (!filename && !file)
        throw CImgArgumentException(_cimglist_instance
                                    "load_cimg(): Specified filename is (null).",
                                    cimglist_instance);

      const ulongT cimg_iobuffer = (ulongT)24*1024*1024;
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      bool loaded = false, endian = cimg::endianness();
      CImg<charT> tmp(256), str_pixeltype(256), str_endian(256);
      *tmp = *str_pixeltype = *str_endian = 0;
      cimg_uint64 csiz;
      int N = 0, W, H, D, C, i, j, err;
      do {
        j = 0; while ((i=std::fgetc(nfile))!='\n' && i>=0 && j<255) tmp[j++] = (char)i; tmp[j] = 0;
      } while (*tmp=='#' && i>=0);
      err = cimg_sscanf(tmp._data,"%d%*c%255[A-Za-z123468_]%*c%255[sA-Za-z_ ]",
                        &N,str_pixeltype._data,str_endian._data);
      if (err<2 || N<0) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): File or CImg header not found in file '%s'.",
                              cimglist_instance,
                              filename?filename:"(FILE*)");
      }
      const cimg_int64 fsiz = cimg::fsize(nfile);
      if (N>fsiz/8) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): Invalid number of images (%d) specified in file '%s'.",
                              cimglist_instance,
                              N,filename?filename:"(FILE*)");
      }
      if (!cimg::strncasecmp("little",str_endian,6)) endian = false;
      else if (!cimg::strncasecmp("big",str_endian,3)) endian = true;
      assign(N);
      _cimg_load_cimg_case("bool",0,0,cimg_uint8);
      _cimg_load_cimg_case("uint8","unsigned_char","uchar",cimg_uint8);
      _cimg_load_cimg_case("int8",0,0,cimg_int8);
      _cimg_load_cimg_case("char",0,0,char);
      _cimg_load_cimg_case("uint16","unsigned_short","ushort",cimg_uint16);
      _cimg_load_cimg_case("int16","short",0,cimg_int16);
      _cimg_load_cimg_case("uint32","unsigned_int","uint",cimg_uint32);
      _cimg_load_cimg_case("int32","int",0,cimg_int32);
      _cimg_load_cimg_case("unsigned_long","ulong",0,cimg_ulong);
      _cimg_load_cimg_case("long",0,0,cimg_long);
      _cimg_load_cimg_case("uint64","unsigned_int64",0,cimg_uint64);
      _cimg_load_cimg_case("int64",0,0,cimg_int64);
      _cimg_load_cimg_case("float32","float",0,cimg_float32);
      _cimg_load_cimg_case("float64","double",0,cimg_float64);

      if (!loaded) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): Unsupported pixel type '%s' for file '%s'.",
                              cimglist_instance,
                              str_pixeltype._data,filename?filename:"(FILE*)");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load a sublist list from a (non compressed) .cimg file.
    /**
      \param filename Filename to read data from.
      \param n0 Starting index of images to read (~0U for max).
      \param n1 Ending index of images to read (~0U for max).
      \param x0 Starting X-coordinates of image regions to read.
      \param y0 Starting Y-coordinates of image regions to read.
      \param z0 Starting Z-coordinates of image regions to read.
      \param c0 Starting C-coordinates of image regions to read.
      \param x1 Ending X-coordinates of image regions to read (~0U for max).
      \param y1 Ending Y-coordinates of image regions to read (~0U for max).
      \param z1 Ending Z-coordinates of image regions to read (~0U for max).
      \param c1 Ending C-coordinates of image regions to read (~0U for max).
    **/
    CImgList<T>& load_cimg(const char *const filename,
                           const unsigned int n0, const unsigned int n1,
                           const unsigned int x0, const unsigned int y0,
                           const unsigned int z0, const unsigned int c0,
                           const unsigned int x1, const unsigned int y1,
                           const unsigned int z1, const unsigned int c1) {
      return _load_cimg(0,filename,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
    }

    //! Load a sublist list from a (non compressed) .cimg file \newinstance.
    static CImgList<T> get_load_cimg(const char *const filename,
                                     const unsigned int n0, const unsigned int n1,
                                     const unsigned int x0, const unsigned int y0,
                                     const unsigned int z0, const unsigned int c0,
                                     const unsigned int x1, const unsigned int y1,
                                     const unsigned int z1, const unsigned int c1) {
      return CImgList<T>().load_cimg(filename,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
    }

    //! Load a sub-image list from a (non compressed) .cimg file \overload.
    CImgList<T>& load_cimg(std::FILE *const file,
                           const unsigned int n0, const unsigned int n1,
                           const unsigned int x0, const unsigned int y0,
                           const unsigned int z0, const unsigned int c0,
                           const unsigned int x1, const unsigned int y1,
                           const unsigned int z1, const unsigned int c1) {
      return _load_cimg(file,0,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
    }

    //! Load a sub-image list from a (non compressed) .cimg file \newinstance.
    static CImgList<T> get_load_cimg(std::FILE *const file,
                                     const unsigned int n0, const unsigned int n1,
                                     const unsigned int x0, const unsigned int y0,
                                     const unsigned int z0, const unsigned int c0,
                                     const unsigned int x1, const unsigned int y1,
                                     const unsigned int z1, const unsigned int c1) {
      return CImgList<T>().load_cimg(file,n0,n1,x0,y0,z0,c0,x1,y1,z1,c1);
    }

    CImgList<T>& _load_cimg(std::FILE *const file, const char *const filename,
                            const unsigned int n0, const unsigned int n1,
                            const unsigned int x0, const unsigned int y0,
                            const unsigned int z0, const unsigned int c0,
                            const unsigned int x1, const unsigned int y1,
                            const unsigned int z1, const unsigned int c1) {
#define _cimg_load_cimg_case2(Ts1,Ts2,Ts3,Tss) \
      if (!loaded && ((Ts1 && !cimg::strcasecmp(Ts1,str_pixeltype)) || \
                      (Ts2 && !cimg::strcasecmp(Ts2,str_pixeltype)) || \
                      (Ts3 && !cimg::strcasecmp(Ts3,str_pixeltype)))) { \
        for (unsigned int l = 0; l<=nn1; ++l) { \
          j = 0; while ((i=std::fgetc(nfile))!='\n' && i>=0 && j<255) tmp[j++] = (char)i; tmp[j] = 0; \
          W = H = D = C = 0; \
          if (cimg_sscanf(tmp._data,"%d %d %d %d",&W,&H,&D,&C)!=4) \
            throw CImgIOException(_cimglist_instance \
                                  "load_cimg(): Invalid specified size (%d,%d,%d,%d) of image %u in file '%s'", \
                                  cimglist_instance, \
                                  W,H,D,C,l,filename?filename:"(FILE*)"); \
          if (W*H*D*C>0) { \
            if (l<nn0 || nx0>=(unsigned int)W || ny0>=(unsigned int)H || nz0>=(unsigned int)D || nc0>=(unsigned int)C) \
              cimg::fseek(nfile,W*H*D*C*sizeof(Tss),SEEK_CUR); \
            else { \
              const int \
                _nx1 = nx1==~0U?W - 1:(int)nx1, \
                _ny1 = ny1==~0U?H - 1:(int)ny1, \
                _nz1 = nz1==~0U?D - 1:(int)nz1, \
                _nc1 = nc1==~0U?C - 1:(int)nc1; \
              if (_nx1>=W || _ny1>=H || _nz1>=D || _nc1>=C) \
                throw CImgArgumentException(_cimglist_instance \
                                            "load_cimg(): Invalid specified coordinates " \
                                            "[%u](%u,%u,%u,%u) -> [%u](%u,%u,%u,%u) " \
                                            "because image [%u] in file '%s' has size (%u,%u,%u,%u).", \
                                            cimglist_instance, \
                                            n0,x0,y0,z0,c0,n1,x1,y1,z1,c1,l,filename?filename:"(FILE*)",W,H,D,C); \
              CImg<Tss> raw(1 + _nx1 - nx0); \
              CImg<T> &img = _data[l - nn0]; \
              img.assign(1 + _nx1 - nx0,1 + _ny1 - ny0,1 + _nz1 - nz0,1 + _nc1 - nc0); \
              T *ptrd = img._data; \
              ulongT skipvb = nc0*W*H*D*sizeof(Tss); \
              if (skipvb) cimg::fseek(nfile,skipvb,SEEK_CUR); \
              for (unsigned int c = 1 + _nc1 - nc0; c; --c) { \
                const ulongT skipzb = nz0*W*H*sizeof(Tss); \
                if (skipzb) cimg::fseek(nfile,skipzb,SEEK_CUR); \
                for (unsigned int z = 1 + _nz1 - nz0; z; --z) { \
                  const ulongT skipyb = ny0*W*sizeof(Tss); \
                  if (skipyb) cimg::fseek(nfile,skipyb,SEEK_CUR); \
                  for (unsigned int y = 1 + _ny1 - ny0; y; --y) { \
                    const ulongT skipxb = nx0*sizeof(Tss); \
                    if (skipxb) cimg::fseek(nfile,skipxb,SEEK_CUR); \
                    cimg::fread(raw._data,raw._width,nfile); \
                    if (endian!=cimg::endianness()) cimg::invert_endianness(raw._data,raw._width); \
                    const Tss *ptrs = raw._data; \
                    for (unsigned int off = raw._width; off; --off) *(ptrd++) = (T)*(ptrs++); \
                    const ulongT skipxe = (W - 1 - _nx1)*sizeof(Tss); \
                    if (skipxe) cimg::fseek(nfile,skipxe,SEEK_CUR); \
                  } \
                  const ulongT skipye = (H - 1 - _ny1)*W*sizeof(Tss); \
                  if (skipye) cimg::fseek(nfile,skipye,SEEK_CUR); \
                } \
                const ulongT skipze = (D - 1 - _nz1)*W*H*sizeof(Tss); \
                if (skipze) cimg::fseek(nfile,skipze,SEEK_CUR); \
              } \
              const ulongT skipve = (C - 1 - _nc1)*W*H*D*sizeof(Tss); \
              if (skipve) cimg::fseek(nfile,skipve,SEEK_CUR); \
            } \
          } \
        } \
        loaded = true; \
      }

      if (!filename && !file)
        throw CImgArgumentException(_cimglist_instance
                                    "load_cimg(): Specified filename is (null).",
                                    cimglist_instance);
      unsigned int
        nn0 = std::min(n0,n1), nn1 = std::max(n0,n1),
        nx0 = std::min(x0,x1), nx1 = std::max(x0,x1),
        ny0 = std::min(y0,y1), ny1 = std::max(y0,y1),
        nz0 = std::min(z0,z1), nz1 = std::max(z0,z1),
        nc0 = std::min(c0,c1), nc1 = std::max(c0,c1);

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      bool loaded = false, endian = cimg::endianness();
      CImg<charT> tmp(256), str_pixeltype(256), str_endian(256);
      *tmp = *str_pixeltype = *str_endian = 0;
      int N = 0, W, H, D, C, i, j, err;
      j = 0; while ((i=std::fgetc(nfile))!='\n' && i!=EOF && j<256) tmp[j++] = (char)i; tmp[j] = 0;
      err = cimg_sscanf(tmp._data,"%d%*c%255[A-Za-z123468_]%*c%255[sA-Za-z_ ]",
                        &N,str_pixeltype._data,str_endian._data);
      if (err<2 || N<0) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): CImg header not found in file '%s'.",
                              cimglist_instance,
                              filename?filename:"(FILE*)");
      }
      const cimg_int64 fsiz = cimg::fsize(nfile);
      if (N>fsiz/8) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): Invalid number of images (%d) specified in file '%s'.",
                              cimglist_instance,
                              N,filename?filename:"(FILE*)");
      }
      if (!cimg::strncasecmp("little",str_endian,6)) endian = false;
      else if (!cimg::strncasecmp("big",str_endian,3)) endian = true;
      nn1 = n1==~0U?(unsigned int)N - 1:n1;
      if (nn1>=(unsigned int)N)
        throw CImgArgumentException(_cimglist_instance
                                    "load_cimg(): Invalid specified coordinates [%u](%u,%u,%u,%u) -> [%u](%u,%u,%u,%u) "
                                    "because file '%s' contains only %d images.",
                                    cimglist_instance,
                                    n0,x0,y0,z0,c0,n1,x1,y1,z1,c1,filename?filename:"(FILE*)",N);
      assign(1 + nn1 - n0);
      _cimg_load_cimg_case2("bool",0,0,cimg_uint8);
      _cimg_load_cimg_case2("uint8","unsigned char","uchar",cimg_uint8);
      _cimg_load_cimg_case2("int8",0,0,cimg_int8);
      _cimg_load_cimg_case2("char",0,0,char);
      _cimg_load_cimg_case2("uint16","unsigned_short","ushort",cimg_uint16);
      _cimg_load_cimg_case2("int16","short",0,cimg_int16);
      _cimg_load_cimg_case2("uint32","unsigned_int","uint",cimg_uint32);
      _cimg_load_cimg_case2("int32","int",0,cimg_int32);
      _cimg_load_cimg_case2("unsigned_long","ulong",0,cimg_ulong);
      _cimg_load_cimg_case2("long",0,0,cimg_long);
      _cimg_load_cimg_case2("uint64","unsigned_int64",0,cimg_uint64);
      _cimg_load_cimg_case2("int64",0,0,cimg_int64);
      _cimg_load_cimg_case2("float32","float",0,cimg_float32);
      _cimg_load_cimg_case2("float64","double",0,cimg_float64);
      if (!loaded) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "load_cimg(): Unsupported pixel type '%s' for file '%s'.",
                              cimglist_instance,
                              str_pixeltype._data,filename?filename:"(FILE*)");
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load a list from a PAR/REC (Philips) file.
    /**
      \param filename Filename to read data from.
    **/
    CImgList<T>& load_parrec(const char *const filename) {
      if (!filename)
        throw CImgArgumentException(_cimglist_instance
                                    "load_parrec(): Specified filename is (null).",
                                    cimglist_instance);

      CImg<charT> body(1024), filenamepar(1024), filenamerec(1024);
      *body = *filenamepar = *filenamerec = 0;
      const char *const ext = cimg::split_filename(filename,body);
      if (!std::strcmp(ext,"par")) {
        std::strncpy(filenamepar,filename,filenamepar._width - 1);
        cimg_snprintf(filenamerec,filenamerec._width,"%s.rec",body._data);
      }
      if (!std::strcmp(ext,"PAR")) {
        std::strncpy(filenamepar,filename,filenamepar._width - 1);
        cimg_snprintf(filenamerec,filenamerec._width,"%s.REC",body._data);
      }
      if (!std::strcmp(ext,"rec")) {
        std::strncpy(filenamerec,filename,filenamerec._width - 1);
        cimg_snprintf(filenamepar,filenamepar._width,"%s.par",body._data);
      }
      if (!std::strcmp(ext,"REC")) {
        std::strncpy(filenamerec,filename,filenamerec._width - 1);
        cimg_snprintf(filenamepar,filenamepar._width,"%s.PAR",body._data);
      }
      std::FILE *file = cimg::fopen(filenamepar,"r");

      // Parse header file.
      CImgList<floatT> st_slices;
      CImgList<uintT> st_global;
      CImg<charT> line(256); *line = 0;
      int err;
      do { err = std::fscanf(file,"%255[^\n]%*c",line._data); } while (err!=EOF && (*line=='#' || *line=='.'));
      do {
        unsigned int sn,size_x,size_y,pixsize;
        float rs,ri,ss;
        err = std::fscanf(file,"%u%*u%*u%*u%*u%*u%*u%u%*u%u%u%g%g%g%*[^\n]",&sn,&pixsize,&size_x,&size_y,&ri,&rs,&ss);
        if (err==7) {
          CImg<floatT>::vector((float)sn,(float)pixsize,(float)size_x,(float)size_y,ri,rs,ss,0).move_to(st_slices);
          unsigned int i; for (i = 0; i<st_global._width && sn<=st_global[i][2]; ++i) {}
          if (i==st_global._width) CImg<uintT>::vector(size_x,size_y,sn).move_to(st_global);
          else {
            CImg<uintT> &vec = st_global[i];
            if (size_x>vec[0]) vec[0] = size_x;
            if (size_y>vec[1]) vec[1] = size_y;
            vec[2] = sn;
          }
          st_slices[st_slices._width - 1][7] = (float)i;
        }
      } while (err==7);

      // Read data.
      std::FILE *file2 = cimg::fopen(filenamerec,"rb");
      cimglist_for(st_global,l) {
        const CImg<uintT>& vec = st_global[l];
        CImg<T>(vec[0],vec[1],vec[2]).move_to(*this);
      }

      cimglist_for(st_slices,l) {
        const CImg<floatT>& vec = st_slices[l];
        const unsigned int
          sn = (unsigned int)vec[0] - 1,
          pixsize = (unsigned int)vec[1],
          size_x = (unsigned int)vec[2],
          size_y = (unsigned int)vec[3],
          imn = (unsigned int)vec[7];
        const float ri = vec[4], rs = vec[5], ss = vec[6];
        switch (pixsize) {
        case 8 : {
          CImg<ucharT> buf(size_x,size_y);
          cimg::fread(buf._data,size_x*size_y,file2);
          if (cimg::endianness()) cimg::invert_endianness(buf._data,size_x*size_y);
          CImg<T>& img = (*this)[imn];
          cimg_forXY(img,x,y) img(x,y,sn) = (T)(( buf(x,y)*rs + ri )/(rs*ss));
        } break;
        case 16 : {
          CImg<ushortT> buf(size_x,size_y);
          cimg::fread(buf._data,size_x*size_y,file2);
          if (cimg::endianness()) cimg::invert_endianness(buf._data,size_x*size_y);
          CImg<T>& img = (*this)[imn];
          cimg_forXY(img,x,y) img(x,y,sn) = (T)(( buf(x,y)*rs + ri )/(rs*ss));
        } break;
        case 32 : {
          CImg<uintT> buf(size_x,size_y);
          cimg::fread(buf._data,size_x*size_y,file2);
          if (cimg::endianness()) cimg::invert_endianness(buf._data,size_x*size_y);
          CImg<T>& img = (*this)[imn];
          cimg_forXY(img,x,y) img(x,y,sn) = (T)(( buf(x,y)*rs + ri )/(rs*ss));
        } break;
        default :
          cimg::fclose(file);
          cimg::fclose(file2);
          throw CImgIOException(_cimglist_instance
                                "load_parrec(): Unsupported %d-bits pixel type for file '%s'.",
                                cimglist_instance,
                                pixsize,filename);
        }
      }
      cimg::fclose(file);
      cimg::fclose(file2);
      if (!_width)
        throw CImgIOException(_cimglist_instance
                              "load_parrec(): Failed to recognize valid PAR-REC data in file '%s'.",
                              cimglist_instance,
                              filename);
      return *this;
    }

    //! Load a list from a PAR/REC (Philips) file \newinstance.
    static CImgList<T> get_load_parrec(const char *const filename) {
      return CImgList<T>().load_parrec(filename);
    }

    //! Load a list from a YUV image sequence file.
    /**
        \param filename Filename to read data from.
        \param size_x Width of the images.
        \param size_y Height of the images.
        \param chroma_subsampling Type of chroma subsampling. Can be <tt>{ 420 | 422 | 444 }</tt>.
        \param first_frame Index of first image frame to read.
        \param last_frame Index of last image frame to read.
        \param step_frame Step applied between each frame.
        \param yuv2rgb Apply YUV to RGB transformation during reading.
    **/
    CImgList<T>& load_yuv(const char *const filename,
                          const unsigned int size_x, const unsigned int size_y,
                          const unsigned int chroma_subsampling=444,
                          const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                          const unsigned int step_frame=1, const bool yuv2rgb=true) {
      return _load_yuv(0,filename,size_x,size_y,chroma_subsampling,
                       first_frame,last_frame,step_frame,yuv2rgb);
    }

    //! Load a list from a YUV image sequence file \newinstance.
    static CImgList<T> get_load_yuv(const char *const filename,
                                    const unsigned int size_x, const unsigned int size_y=1,
                                    const unsigned int chroma_subsampling=444,
                                    const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                    const unsigned int step_frame=1, const bool yuv2rgb=true) {
      return CImgList<T>().load_yuv(filename,size_x,size_y,chroma_subsampling,
                                    first_frame,last_frame,step_frame,yuv2rgb);
    }

    //! Load a list from an image sequence YUV file \inplace.
    CImgList<T>& load_yuv(std::FILE *const file,
                          const unsigned int size_x, const unsigned int size_y,
                          const unsigned int chroma_subsampling=444,
                          const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                          const unsigned int step_frame=1, const bool yuv2rgb=true) {
      return _load_yuv(file,0,size_x,size_y,chroma_subsampling,
                       first_frame,last_frame,step_frame,yuv2rgb);
    }

    //! Load a list from an image sequence YUV file \newinstance.
    static CImgList<T> get_load_yuv(std::FILE *const file,
                                    const unsigned int size_x, const unsigned int size_y=1,
                                    const unsigned int chroma_subsampling=444,
                                    const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                    const unsigned int step_frame=1, const bool yuv2rgb=true) {
      return CImgList<T>().load_yuv(file,size_x,size_y,chroma_subsampling,
                                    first_frame,last_frame,step_frame,yuv2rgb);
    }

    CImgList<T>& _load_yuv(std::FILE *const file, const char *const filename,
                           const unsigned int size_x, const unsigned int size_y,
                           const unsigned int chroma_subsampling,
                           const unsigned int first_frame, const unsigned int last_frame,
                           const unsigned int step_frame, const bool yuv2rgb) {
      if (!filename && !file)
        throw CImgArgumentException(_cimglist_instance
                                    "load_yuv(): Specified filename is (null).",
                                    cimglist_instance);
      if (chroma_subsampling!=420 && chroma_subsampling!=422 && chroma_subsampling!=444)
        throw CImgArgumentException(_cimglist_instance
                                    "load_yuv(): Specified chroma subsampling %u is invalid, for file '%s'.",
                                    cimglist_instance,
                                    chroma_subsampling,filename?filename:"(FILE*)");
      const unsigned int
        cfx = chroma_subsampling==420 || chroma_subsampling==422?2:1,
        cfy = chroma_subsampling==420?2:1,
        nfirst_frame = first_frame<last_frame?first_frame:last_frame,
        nlast_frame = first_frame<last_frame?last_frame:first_frame,
        nstep_frame = step_frame?step_frame:1;

      if (!size_x || !size_y || size_x%cfx || size_y%cfy)
        throw CImgArgumentException(_cimglist_instance
                                    "load_yuv(): Specified dimensions (%u,%u) are invalid, for file '%s'.",
                                    cimglist_instance,
                                    size_x,size_y,filename?filename:"(FILE*)");

      CImg<ucharT> YUV(size_x,size_y,1,3), UV(size_x/cfx,size_y/cfy,1,2);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      bool stop_flag = false;
      int err;
      if (nfirst_frame) {
        err = cimg::fseek(nfile,(uint64T)nfirst_frame*(YUV._width*YUV._height + 2*UV._width*UV._height),SEEK_CUR);
        if (err) {
          if (!file) cimg::fclose(nfile);
          throw CImgIOException(_cimglist_instance
                                "load_yuv(): File '%s' doesn't contain frame number %u.",
                                cimglist_instance,
                                filename?filename:"(FILE*)",nfirst_frame);
        }
      }
      unsigned int frame;
      for (frame = nfirst_frame; !stop_flag && frame<=nlast_frame; frame+=nstep_frame) {
        YUV.get_shared_channel(0).fill(0);
        // *TRY* to read the luminance part, do not replace by cimg::fread!
        err = (int)std::fread((void*)(YUV._data),1,(size_t)YUV._width*YUV._height,nfile);
        if (err!=(int)(YUV._width*YUV._height)) {
          stop_flag = true;
          if (err>0)
            cimg::warn(_cimglist_instance
                       "load_yuv(): File '%s' contains incomplete data or given image dimensions "
                       "(%u,%u) are incorrect.",
                       cimglist_instance,
                       filename?filename:"(FILE*)",size_x,size_y);
        } else {
          UV.fill(0);
          // *TRY* to read the luminance part, do not replace by cimg::fread!
          err = (int)std::fread((void*)(UV._data),1,(size_t)UV.size(),nfile);
          if (err!=(int)(UV.size())) {
            stop_flag = true;
            if (err>0)
              cimg::warn(_cimglist_instance
                         "load_yuv(): File '%s' contains incomplete data or given image dimensions "
                         "(%u,%u) are incorrect.",
                         cimglist_instance,
                         filename?filename:"(FILE*)",size_x,size_y);
          } else {
            const ucharT *ptrs1 = UV._data, *ptrs2 = UV.data(0,0,0,1);
            ucharT *ptrd1 = YUV.data(0,0,0,1), *ptrd2 = YUV.data(0,0,0,2);
            const unsigned int wd = YUV._width;
            switch (chroma_subsampling) {
            case 420 :
              cimg_forY(UV,y) {
                cimg_forX(UV,x) {
                  const ucharT U = *(ptrs1++), V = *(ptrs2++);
                  ptrd1[wd] = U; *(ptrd1)++ = U;
                  ptrd1[wd] = U; *(ptrd1)++ = U;
                  ptrd2[wd] = V; *(ptrd2)++ = V;
                  ptrd2[wd] = V; *(ptrd2)++ = V;
                }
                ptrd1+=wd; ptrd2+=wd;
              }
              break;
            case 422 :
              cimg_forXY(UV,x,y) {
                const ucharT U = *(ptrs1++), V = *(ptrs2++);
                *(ptrd1++) = U; *(ptrd1++) = U;
                *(ptrd2++) = V; *(ptrd2++) = V;
              }
              break;
            default :
              YUV.draw_image(0,0,0,1,UV);
            }
            if (yuv2rgb) YUV.YCbCrtoRGB();
            insert(YUV);
            if (nstep_frame>1) cimg::fseek(nfile,(uint64T)(nstep_frame - 1)*(size_x*size_y + size_x*size_y/2),SEEK_CUR);
          }
        }
      }
      if (is_empty())
        throw CImgIOException(_cimglist_instance
                              "load_yuv() : Missing data in file '%s'.",
                              cimglist_instance,
                              filename?filename:"(FILE*)");
      if (stop_flag && nlast_frame!=~0U && frame!=nlast_frame)
        cimg::warn(_cimglist_instance
                   "load_yuv(): Frame %d not reached since only %u frames were found in file '%s'.",
                   cimglist_instance,
                   nlast_frame,frame - 1,filename?filename:"(FILE*)");

      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Load an image from a video file, using OpenCV library.
    /**
      \param filename Filename, as a C-string.
      \param first_frame Index of the first frame to read.
      \param last_frame Index of the last frame to read (can be higher than the actual number of frames, e.g. '~0U').
      \param step_frame Step value for frame reading.
      \note If step_frame==0, the current video stream is forced to be released (without any frames read).
    **/
    CImgList<T>& load_video(const char *const filename,
                            const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                            const unsigned int step_frame=1) {
#ifndef cimg_use_opencv
      if (first_frame || last_frame!=~0U || step_frame>1)
        throw CImgArgumentException(_cimglist_instance
                                    "load_video() : File '%s', arguments 'first_frame', 'last_frame' "
                                    "and 'step_frame' requires features from the OpenCV library "
                                    "('-Dcimg_use_opencv' must be defined).",
                                    cimglist_instance,filename);
      return load_ffmpeg_external(filename);
#else
      static cv::VideoCapture *captures[32] = {};
      static CImgList<charT> filenames(32);
      static CImg<uintT> positions(32,1,1,1,0);
      static int last_used_index = -1;

      // Detect if a video capture already exists for the specified filename.
      cimg::mutex(9);
      int index = -1;
      if (filename) {
        if (last_used_index>=0 && !std::strcmp(filename,filenames[last_used_index])) {
          index = last_used_index;
        } else cimglist_for(filenames,l) if (filenames[l] && !std::strcmp(filename,filenames[l])) {
            index = l; break;
          }
      } else index = last_used_index;
      cimg::mutex(9,0);

      // Release stream if needed.
      if (!step_frame || (index>=0 && positions[index]>first_frame)) {
        if (index>=0) {
          cimg::mutex(9);
          captures[index]->release();
          delete captures[index];
          captures[index] = 0;
          positions[index] = 0;
          filenames[index].assign();
          if (last_used_index==index) last_used_index = -1;
          index = -1;
          cimg::mutex(9,0);
        } else
          if (filename)
            cimg::warn(_cimglist_instance
                       "load_video() : File '%s', no opened video stream associated with filename found.",
                       cimglist_instance,filename);
          else
            cimg::warn(_cimglist_instance
                       "load_video() : No opened video stream found.",
                       cimglist_instance,filename);
        if (!step_frame) return *this;
      }

      // Find empty slot for capturing video stream.
      if (index<0) {
        if (!filename)
          throw CImgArgumentException(_cimglist_instance
                                      "load_video(): No already open video reader found. You must specify a "
                                      "non-(null) filename argument for the first call.",
                                      cimglist_instance);
        else { cimg::mutex(9); cimglist_for(filenames,l) if (!filenames[l]) { index = l; break; } cimg::mutex(9,0); }
        if (index<0)
          throw CImgIOException(_cimglist_instance
                                "load_video(): File '%s', no video reader slots available. "
                                "You have to release some of your previously opened videos.",
                                cimglist_instance,filename);
        cimg::mutex(9);
        captures[index] = new cv::VideoCapture(filename);
        positions[index] = 0;
        if (!captures[index]->isOpened()) {
          delete captures[index];
          captures[index] = 0;
          cimg::mutex(9,0);
          cimg::fclose(cimg::fopen(filename,"rb")); // Check file availability
          throw CImgIOException(_cimglist_instance
                                "load_video(): File '%s', unable to detect format of video file.",
                                cimglist_instance,filename);
        }
        CImg<charT>::string(filename).move_to(filenames[index]);
        cimg::mutex(9,0);
      }

      cimg::mutex(9);
      const unsigned int nb_frames = (unsigned int)std::max(0.,captures[index]->get(_cimg_cap_prop_frame_count));
      cimg::mutex(9,0);
      assign();

      // Skip frames if requested.
      bool go_on = true;
      unsigned int &pos = positions[index];
      while (pos<first_frame) {
        cimg::mutex(9);
        if (!captures[index]->grab()) { cimg::mutex(9,0); go_on = false; break; }
        cimg::mutex(9,0);
        ++pos;
      }

      // Read and convert frames.
      const unsigned int _last_frame = std::min(nb_frames?nb_frames - 1:~0U,last_frame);
      while (go_on && pos<=_last_frame) {
        cv::Mat cvimg;
        cimg::mutex(9);
        if (captures[index]->read(cvimg)) { CImg<T>::_cvmat2cimg(cvimg).move_to(*this); ++pos; }
        else go_on = false;
        cimg::mutex(9,0);
        if (go_on)
          for (unsigned int i = 1; go_on && i<step_frame && pos<=_last_frame; ++i, ++pos) {
            cimg::mutex(9);
            if (!captures[index]->grab()) go_on = false;
            cimg::mutex(9,0);
          }
      }

      if (!go_on || (nb_frames && pos>=nb_frames)) { // Close video stream when necessary
        cimg::mutex(9);
        captures[index]->release();
        delete captures[index];
        captures[index] = 0;
        filenames[index].assign();
        positions[index] = 0;
        index = -1;
        cimg::mutex(9,0);
      }

      cimg::mutex(9);
      last_used_index = index;
      cimg::mutex(9,0);

      if (is_empty())
        throw CImgIOException(_cimglist_instance
                              "load_video(): File '%s', unable to locate frame %u.",
                              cimglist_instance,filename,first_frame);
      return *this;
#endif
    }

    //! Load an image from a video file, using OpenCV library \newinstance.
    static CImgList<T> get_load_video(const char *const filename,
                           const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                           const unsigned int step_frame=1) {
      return CImgList<T>().load_video(filename,first_frame,last_frame,step_frame);
    }

    //! Load an image from a video file using the external tool 'ffmpeg'.
    /**
      \param filename Filename to read data from.
    **/
    CImgList<T>& load_ffmpeg_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimglist_instance
                                    "load_ffmpeg_external(): Specified filename is (null) or does not exist.",
                                    cimglist_instance);
      CImg<charT> command(1024), filename_tmp(256), filename_tmp2(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_000001.ppm",filename_tmp._data);
      } while (cimg::path_exists(filename_tmp2));
      cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_%%6d.ppm",filename_tmp._data);
      cimg_snprintf(command,command._width,"\"%s\" -v -8 -i \"%s\" \"%s\"",
                    cimg::ffmpeg_path(),
                    CImg<charT>::string(filename)._system_strescape().data(),
                    CImg<charT>::string(filename_tmp2)._system_strescape().data());
      if (cimg::system(command,cimg::ffmpeg_path())!=0)
        throw CImgIOException(_cimglist_instance
                              "load_ffmpeg_external(): Failed to open file '%s' with external command 'ffmpeg'.",
                              cimglist_instance,
                              filename);
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      assign();
      unsigned int i = 1;
      for (bool stop_flag = false; !stop_flag; ++i) {
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_%.6u.ppm",filename_tmp._data,i);
        CImg<T> img;
        try { img.load_pnm(filename_tmp2); }
        catch (CImgException&) { stop_flag = true; }
        if (img) { img.move_to(*this); std::remove(filename_tmp2); }
      }
      cimg::exception_mode(omode);
      if (is_empty())
        throw CImgIOException(_cimglist_instance
                              "load_ffmpeg_external(): Failed to open file '%s' with external command 'ffmpeg'.",
                              cimglist_instance,
                              filename);
      return *this;
    }

    //! Load an image from a video file using the external tool 'ffmpeg' \newinstance.
    static CImgList<T> get_load_ffmpeg_external(const char *const filename) {
      return CImgList<T>().load_ffmpeg_external(filename);
    }

    //! Load gif file, using ImageMagick or GraphicsMagick's external tools.
    /**
      \param filename Filename to read data from.
    **/
    CImgList<T>& load_gif_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgArgumentException(_cimglist_instance
                                    "load_gif_external(): Specified filename is (null) or does not exist.",
                                    cimglist_instance);
      if (!_load_gif_external(filename,false))
        if (!_load_gif_external(filename,true))
          try { assign(CImg<T>().load_other(filename)); } catch (CImgException&) { assign(); }
      if (is_empty())
        throw CImgIOException(_cimglist_instance
                              "load_gif_external(): Failed to open file '%s'.",
                              cimglist_instance,filename);
      return *this;
    }

    CImgList<T>& _load_gif_external(const char *const filename, const bool use_graphicsmagick=false) {
      CImg<charT> command(1024), filename_tmp(256), filename_tmp2(256);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        if (use_graphicsmagick) cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s.png.0",filename_tmp._data);
        else cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s-0.png",filename_tmp._data);
      } while (cimg::path_exists(filename_tmp2));
      if (use_graphicsmagick) cimg_snprintf(command,command._width,"%s convert \"%s\" \"%s.png\"",
                                            cimg::graphicsmagick_path(),
                                            CImg<charT>::string(filename)._system_strescape().data(),
                                            CImg<charT>::string(filename_tmp)._system_strescape().data());
      else cimg_snprintf(command,command._width,"%s -coalesce \"%s\" \"%s.png\"",
                         cimg::imagemagick_path(),
                         CImg<charT>::string(filename)._system_strescape().data(),
                         CImg<charT>::string(filename_tmp)._system_strescape().data());
      cimg::system(command,cimg::imagemagick_path());
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      assign();

      // Try to read a single-frame GIF.
      cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s.png",filename_tmp._data);
      CImg<T> img;
      try { img.load_png(filename_tmp2); }
      catch (CImgException&) { }
      if (img) { img.move_to(*this); std::remove(filename_tmp2); }
      else { // Try to read an animated GIF
        unsigned int i = 0;
        for (bool stop_flag = false; !stop_flag; ++i) {
          if (use_graphicsmagick) cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s.png.%u",filename_tmp._data,i);
          else cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s-%u.png",filename_tmp._data,i);
          try { img.load_png(filename_tmp2); }
          catch (CImgException&) { stop_flag = true; }
          if (img) { img.move_to(*this); std::remove(filename_tmp2); }
        }
      }
      cimg::exception_mode(omode);
      return *this;
    }

    //! Load gif file, using ImageMagick or GraphicsMagick's external tools \newinstance.
    static CImgList<T> get_load_gif_external(const char *const filename) {
      return CImgList<T>().load_gif_external(filename);
    }

    //! Load a gzipped list, using external tool 'gunzip'.
    /**
      \param filename Filename to read data from.
    **/
    CImgList<T>& load_gzip_external(const char *const filename) {
      if (!filename || !cimg::is_file(filename))
        throw CImgIOException(_cimglist_instance
                              "load_gzip_external(): Specified filename is (null) or does not exist.",
                              cimglist_instance);
      CImg<charT> command(1024), filename_tmp(256), body(256);
      const char
        *ext = cimg::split_filename(filename,body),
        *ext2 = cimg::split_filename(body,0);
      do {
        if (!cimg::strcasecmp(ext,"gz")) {
          if (*ext2) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                   cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext2);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        } else {
          if (*ext) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                  cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        }
      } while (cimg::path_exists(filename_tmp));
      cimg_snprintf(command,command._width,"\"%s\" -c \"%s\" > \"%s\"",
                    cimg::gunzip_path(),
                    CImg<charT>::string(filename)._system_strescape().data(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data());
      if (cimg::system(command,cimg::gunzip_path())!=0)
        throw CImgIOException(_cimglist_instance
                              "load_gzip_external(): Failed to open file '%s'.",
                              cimglist_instance,
                              filename);
      if (!cimg::path_exists(filename_tmp)) {
        cimg::fclose(cimg::fopen(filename,"r"));
        throw CImgIOException(_cimglist_instance
                              "load_gzip_external(): Failed to open file '%s'.",
                              cimglist_instance,
                              filename);

      }
      load(filename_tmp);
      std::remove(filename_tmp);
      return *this;
    }

    //! Load a gzipped list, using external tool 'gunzip' \newinstance.
    static CImgList<T> get_load_gzip_external(const char *const filename) {
      return CImgList<T>().load_gzip_external(filename);
    }

    //! Load images from a TIFF file.
    /**
        \param filename Filename to read data from.
        \param first_frame Index of first image frame to read.
        \param last_frame Index of last image frame to read.
        \param step_frame Step applied between each frame.
        \param[out] bits_per_value Number of bits used to store a scalar value in the image file.
        \param[out] voxel_size Voxel size, as stored in the filename.
        \param[out] description Description, as stored in the filename.
    **/
    CImgList<T>& load_tiff(const char *const filename,
                           const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                           const unsigned int step_frame=1, unsigned int *const bits_per_value=0,
                           float *const voxel_size=0, CImg<charT> *const description=0) {
      const unsigned int
        nfirst_frame = first_frame<last_frame?first_frame:last_frame,
        nstep_frame = step_frame?step_frame:1;
      unsigned int nlast_frame = first_frame<last_frame?last_frame:first_frame;
#ifndef cimg_use_tiff
      cimg::unused(bits_per_value,voxel_size,description);
      if (nfirst_frame || nlast_frame!=~0U || nstep_frame!=1)
        throw CImgArgumentException(_cimglist_instance
                                    "load_tiff(): Unable to load sub-images from file '%s' unless libtiff is enabled.",
                                    cimglist_instance,
                                    filename);

      return assign(CImg<T>::get_load_tiff(filename));
#else
#if cimg_verbosity<3
        TIFFSetWarningHandler(0);
        TIFFSetErrorHandler(0);
#endif
      TIFF *tif = TIFFOpen(filename,"r");
      if (tif) {
        unsigned int nb_images = 0;
        do ++nb_images; while (TIFFReadDirectory(tif));
        if (nfirst_frame>=nb_images || (nlast_frame!=~0U && nlast_frame>=nb_images))
          cimg::warn(_cimglist_instance
                     "load_tiff(): Invalid specified frame range is [%u,%u] (step %u) since "
                     "file '%s' contains %u image(s).",
                     cimglist_instance,
                     nfirst_frame,nlast_frame,nstep_frame,filename,nb_images);

        if (nfirst_frame>=nb_images) return assign();
        if (nlast_frame>=nb_images) nlast_frame = nb_images - 1;
        assign(1 + (nlast_frame - nfirst_frame)/nstep_frame);
        TIFFSetDirectory(tif,0);
        cimglist_for(*this,l)
          _data[l]._load_tiff(tif,nfirst_frame + l*nstep_frame,bits_per_value,voxel_size,description);
        TIFFClose(tif);
      } else throw CImgIOException(_cimglist_instance
                                   "load_tiff(): Failed to open file '%s'.",
                                   cimglist_instance,
                                   filename);
      return *this;
#endif
    }

    //! Load a multi-page TIFF file \newinstance.
    static CImgList<T> get_load_tiff(const char *const filename,
                                     const unsigned int first_frame=0, const unsigned int last_frame=~0U,
                                     const unsigned int step_frame=1, unsigned int *const bits_per_value=0,
                                     float *const voxel_size=0, CImg<charT> *const description=0) {
      return CImgList<T>().load_tiff(filename,first_frame,last_frame,step_frame,bits_per_value,voxel_size,description);
    }

    //@}
    //----------------------------------
    //
    //! \name Data Output
    //@{
    //----------------------------------

    //! Print information about the list on the standard output.
    /**
      \param title Label set to the information displayed.
      \param display_stats Indicates whether image statistics must be computed and displayed.
    **/
    const CImgList<T>& print(const char *const title=0, const bool display_stats=true) const {
      unsigned int msiz = 0;
      cimglist_for(*this,l) msiz+=_data[l].size();
      msiz*=sizeof(T);
      const unsigned int mdisp = msiz<8*1024?0U:msiz<8*1024*1024?1U:2U;
      CImg<charT> _title(64);
      if (!title) cimg_snprintf(_title,_title._width,"CImgList<%s>",pixel_type());
      std::fprintf(cimg::output(),"%s%s%s%s: %sthis%s = %p, %ssize%s = %u/%u [%u %s], %sdata%s = (CImg<%s>*)%p",
                   cimg::t_magenta(),cimg::t_bold(),title?title:_title._data,cimg::t_normal(),
                   cimg::t_bold(),cimg::t_normal(),(void*)this,
                   cimg::t_bold(),cimg::t_normal(),_width,_allocated_width,
                   mdisp==0?msiz:(mdisp==1?(msiz>>10):(msiz>>20)),
                   mdisp==0?"b":(mdisp==1?"Kio":"Mio"),
                   cimg::t_bold(),cimg::t_normal(),pixel_type(),(void*)begin());
      if (_data) std::fprintf(cimg::output(),"..%p.\n",(void*)((char*)end() - 1));
      else std::fprintf(cimg::output(),".\n");

      char tmp[16] = {};
      cimglist_for(*this,ll) {
        cimg_snprintf(tmp,sizeof(tmp),"[%d]",ll);
        std::fprintf(cimg::output(),"  ");
        _data[ll].print(tmp,display_stats);
        if (ll==3 && width()>8) { ll = width() - 5; std::fprintf(cimg::output(),"  ...\n"); }
      }
      std::fflush(cimg::output());
      return *this;
    }

    //! Display the current CImgList instance in an existing CImgDisplay window (by reference).
    /**
       \param disp Reference to an existing CImgDisplay instance, where the current image list will be displayed.
       \param axis Concatenation axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
       \param align Concatenation alignment.
       \note This function displays the list images of the current CImgList instance into an existing
         CImgDisplay window.
       Images of the list are appended in a single temporary image for visualization purposes.
       The function returns immediately.
    **/
    const CImgList<T>& display(CImgDisplay &disp, const char axis='x', const float align=0) const {
      disp.display(*this,axis,align);
      return *this;
    }

    //! Display the current CImgList instance in a new display window.
    /**
        \param disp Display window.
        \param display_info Indicates whether image information is displayed on the standard output.
        \param axis Alignment axis for images viewing.
        \param align Concatenation alignment.
        \param[in,out] XYZ Contains the XYZ coordinates at start / exit of the function.
        \param exit_on_anykey Exit function when any key is pressed.
        \note This function opens a new window with a specific title and displays the list images of the
          current CImgList instance into it.
        Images of the list are appended in a single temporary image for visualization purposes.
        The function returns when a key is pressed or the display window is closed by the user.
    **/
    const CImgList<T>& display(CImgDisplay &disp, const bool display_info,
                               const char axis='x', const float align=0,
                               unsigned int *const XYZ=0, const bool exit_on_anykey=false) const {
      bool is_exit = false;
      return _display(disp,0,0,display_info,axis,align,XYZ,exit_on_anykey,0,true,is_exit);
    }

    //! Display the current CImgList instance in a new display window.
    /**
      \param title Title of the opening display window.
      \param display_info Indicates whether list information must be written on standard output.
      \param axis Concatenation axis. Can be <tt>{ 'x' | 'y' | 'z' | 'c' }</tt>.
      \param align Concatenation alignment.
      \param[in,out] XYZ Contains the XYZ coordinates at start / exit of the function.
      \param exit_on_anykey Exit function when any key is pressed.
    **/
    const CImgList<T>& display(const char *const title=0, const bool display_info=true,
                               const char axis='x', const float align=0,
                               unsigned int *const XYZ=0, const bool exit_on_anykey=false) const {
      CImgDisplay disp;
      bool is_exit = false;
      return _display(disp,title,0,display_info,axis,align,XYZ,exit_on_anykey,0,true,is_exit);
    }

    const CImgList<T>& _display(CImgDisplay &disp, const char *const title, const CImgList<charT> *const titles,
                                const bool display_info, const char axis, const float align, unsigned int *const XYZ,
                                const bool exit_on_anykey, const unsigned int orig, const bool is_first_call,
                                bool &is_exit) const {
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "display(): Empty instance.",
                                    cimglist_instance);
      if (!disp) {
        if (axis=='x') {
          unsigned int sum_width = 0, max_height = 0;
          cimglist_for(*this,l) {
            const CImg<T> &img = _data[l];
            const unsigned int
              w = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,false),
              h = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,true);
            sum_width+=w;
            if (h>max_height) max_height = h;
          }
          disp.assign(cimg_fitscreen(sum_width,max_height,1),title?title:titles?titles->__display()._data:0,1);
        } else {
          unsigned int max_width = 0, sum_height = 0;
          cimglist_for(*this,l) {
            const CImg<T> &img = _data[l];
            const unsigned int
              w = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,false),
              h = CImgDisplay::_fitscreen(img._width,img._height,img._depth,128,-85,true);
            if (w>max_width) max_width = w;
            sum_height+=h;
          }
          disp.assign(cimg_fitscreen(max_width,sum_height,1),title?title:titles?titles->__display()._data:0,1);
        }
        if (!title && !titles) disp.set_title("CImgList<%s> (%u)",pixel_type(),_width);
      } else if (title) disp.set_title("%s",title);
      else if (titles) disp.set_title("%s",titles->__display()._data);
      const CImg<char> dtitle = CImg<char>::string(disp.title());
      if (display_info) print(disp.title());
      disp.show().flush();

      if (_width==1) {
        const unsigned int dw = disp._width, dh = disp._height;
        if (!is_first_call)
          disp.resize(cimg_fitscreen(_data[0]._width,_data[0]._height,_data[0]._depth),false);
        disp.set_title("%s (%ux%ux%ux%u)",
                       dtitle.data(),_data[0]._width,_data[0]._height,_data[0]._depth,_data[0]._spectrum);
        _data[0]._display(disp,0,false,XYZ,exit_on_anykey,!is_first_call);
        if (disp.key()) is_exit = true;
        disp.resize(cimg_fitscreen(dw,dh,1),false).set_title("%s",dtitle.data());
      } else {
        bool disp_resize = !is_first_call;
        while (!disp.is_closed() && !is_exit) {
          const CImg<intT> s = _select(disp,0,true,axis,align,exit_on_anykey,orig,disp_resize,!is_first_call,true);
          disp_resize = true;
          if (s[0]<0 && !disp.wheel()) { // No selections done
            if (disp.button()&2) { disp.flush(); break; }
            is_exit = true;
          } else if (disp.wheel()) { // Zoom in/out
            const int wheel = disp.wheel();
            disp.set_wheel();
            if (!is_first_call && wheel<0) break;
            if (wheel>0 && _width>=4) {
              const unsigned int
                delta = std::max(1U,(unsigned int)cimg::round(0.3*_width)),
                ind0 = (unsigned int)std::max(0,s[0] - (int)delta),
                ind1 = (unsigned int)std::min(width() - 1,s[0] + (int)delta);
              if ((ind0!=0 || ind1!=_width - 1) && ind1 - ind0>=3) {
                const CImgList<T> sublist = get_shared_images(ind0,ind1);
                CImgList<charT> t_sublist;
                if (titles) t_sublist = titles->get_shared_images(ind0,ind1);
                sublist._display(disp,0,titles?&t_sublist:0,false,axis,align,XYZ,exit_on_anykey,
                                 orig + ind0,false,is_exit);
              }
            }
          } else if (s[0]!=0 || s[1]!=width() - 1) {
            const CImgList<T> sublist = get_shared_images(s[0],s[1]);
            CImgList<charT> t_sublist;
            if (titles) t_sublist = titles->get_shared_images(s[0],s[1]);
            sublist._display(disp,0,titles?&t_sublist:0,false,axis,align,XYZ,exit_on_anykey,
                             orig + s[0],false,is_exit);
          }
          disp.set_title("%s",dtitle.data());
        }
      }
      return *this;
    }

    // [internal] Return string to describe display title.
    CImg<charT> __display() const {
      CImg<charT> res, str;
      cimglist_for(*this,l) {
        CImg<charT>::string((char*)_data[l]._data).move_to(str);
        if (l!=width() - 1) {
          str.resize(str._width + 1,1,1,1,0);
          str[str._width - 2] = ',';
          str[str._width - 1] = ' ';
        }
        res.append(str,'x');
      }
      if (!res) return CImg<charT>(1,1,1,1,0).move_to(res);
      cimg::strellipsize(res,128,false);
      if (_width>1) {
        const unsigned int l = (unsigned int)std::strlen(res);
        if (res._width<=l + 16) res.resize(l + 16,1,1,1,0);
        cimg_snprintf(res._data + l,16," (#%u)",_width);
      }
      return res;
    }

    //! Save the list into a file.
    /**
      \param filename Filename to write data to.
      \param number When positive, represents an index added to the filename. Otherwise, no number is added.
      \param digits Number of digits used for adding the number to the filename.
    **/
    const CImgList<T>& save(const char *const filename, const int number=-1, const unsigned int digits=6) const {
      if (!filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save(): Specified filename is (null).",
                                    cimglist_instance);
      // Do not test for empty instances, since .cimg format is able to manage empty instances.
      const bool is_stdout = *filename=='-' && (!filename[1] || filename[1]=='.');
      const char *const ext = cimg::split_filename(filename);
      CImg<charT> nfilename(1024);
      const char *const fn = is_stdout?filename:number>=0?cimg::number_filename(filename,number,digits,nfilename):
        filename;

#ifdef cimglist_save_plugin
      cimglist_save_plugin(fn);
#endif
#ifdef cimglist_save_plugin1
      cimglist_save_plugin1(fn);
#endif
#ifdef cimglist_save_plugin2
      cimglist_save_plugin2(fn);
#endif
#ifdef cimglist_save_plugin3
      cimglist_save_plugin3(fn);
#endif
#ifdef cimglist_save_plugin4
      cimglist_save_plugin4(fn);
#endif
#ifdef cimglist_save_plugin5
      cimglist_save_plugin5(fn);
#endif
#ifdef cimglist_save_plugin6
      cimglist_save_plugin6(fn);
#endif
#ifdef cimglist_save_plugin7
      cimglist_save_plugin7(fn);
#endif
#ifdef cimglist_save_plugin8
      cimglist_save_plugin8(fn);
#endif
      if (!cimg::strcasecmp(ext,"cimgz")) return save_cimg(fn,true);
      else if (!cimg::strcasecmp(ext,"cimg") || !*ext) return save_cimg(fn,false);
      else if (!cimg::strcasecmp(ext,"yuv")) return save_yuv(fn,444,true);
      else if (!cimg::strcasecmp(ext,"avi") ||
               !cimg::strcasecmp(ext,"mov") ||
               !cimg::strcasecmp(ext,"asf") ||
               !cimg::strcasecmp(ext,"divx") ||
               !cimg::strcasecmp(ext,"flv") ||
               !cimg::strcasecmp(ext,"mpg") ||
               !cimg::strcasecmp(ext,"m1v") ||
               !cimg::strcasecmp(ext,"m2v") ||
               !cimg::strcasecmp(ext,"m4v") ||
               !cimg::strcasecmp(ext,"mjp") ||
               !cimg::strcasecmp(ext,"mp4") ||
               !cimg::strcasecmp(ext,"mkv") ||
               !cimg::strcasecmp(ext,"mpe") ||
               !cimg::strcasecmp(ext,"movie") ||
               !cimg::strcasecmp(ext,"ogm") ||
               !cimg::strcasecmp(ext,"ogg") ||
               !cimg::strcasecmp(ext,"ogv") ||
               !cimg::strcasecmp(ext,"qt") ||
               !cimg::strcasecmp(ext,"rm") ||
               !cimg::strcasecmp(ext,"vob") ||
               !cimg::strcasecmp(ext,"webm") ||
               !cimg::strcasecmp(ext,"wmv") ||
               !cimg::strcasecmp(ext,"xvid") ||
               !cimg::strcasecmp(ext,"mpeg")) return save_video(fn);
#ifdef cimg_use_tiff
      else if (!cimg::strcasecmp(ext,"tif") ||
          !cimg::strcasecmp(ext,"tiff")) return save_tiff(fn);
#endif
      else if (!cimg::strcasecmp(ext,"gz")) return save_gzip_external(fn);
      else {
        if (_width==1) _data[0].save(fn,-1);
        else cimglist_for(*this,l) { _data[l].save(fn,is_stdout?-1:l); if (is_stdout) std::fputc(EOF,cimg::_stdout()); }
      }
      return *this;
    }

    //! Indicates whether an image list can be saved as one single file or not.
    /**
       \param filename Filename, as a C-string.
       \return \c true if the file format supports multiple images, \c false otherwise.
    **/
    static bool is_saveable(const char *const filename) {
      const char *const ext = cimg::split_filename(filename);
      if (!cimg::strcasecmp(ext,"cimgz") ||
#ifdef cimg_use_tiff
          !cimg::strcasecmp(ext,"tif") ||
          !cimg::strcasecmp(ext,"tiff") ||
#endif
          !cimg::strcasecmp(ext,"yuv") ||
          !cimg::strcasecmp(ext,"avi") ||
          !cimg::strcasecmp(ext,"mov") ||
          !cimg::strcasecmp(ext,"asf") ||
          !cimg::strcasecmp(ext,"divx") ||
          !cimg::strcasecmp(ext,"flv") ||
          !cimg::strcasecmp(ext,"mpg") ||
          !cimg::strcasecmp(ext,"m1v") ||
          !cimg::strcasecmp(ext,"m2v") ||
          !cimg::strcasecmp(ext,"m4v") ||
          !cimg::strcasecmp(ext,"mjp") ||
          !cimg::strcasecmp(ext,"mp4") ||
          !cimg::strcasecmp(ext,"mkv") ||
          !cimg::strcasecmp(ext,"mpe") ||
          !cimg::strcasecmp(ext,"movie") ||
          !cimg::strcasecmp(ext,"ogm") ||
          !cimg::strcasecmp(ext,"ogg") ||
          !cimg::strcasecmp(ext,"ogv") ||
          !cimg::strcasecmp(ext,"qt") ||
          !cimg::strcasecmp(ext,"rm") ||
          !cimg::strcasecmp(ext,"vob") ||
          !cimg::strcasecmp(ext,"webm") ||
          !cimg::strcasecmp(ext,"wmv") ||
          !cimg::strcasecmp(ext,"xvid") ||
          !cimg::strcasecmp(ext,"mpeg")) return true;
      return false;
    }

    //! Save the image sequence as a GIF animated file.
    /**
       \param filename Filename to write data to.
       \param fps Number of desired frames per second.
       \param nb_loops Number of loops (\c 0 for infinite looping).
    **/
    const CImgList<T>& save_gif_external(const char *const filename, const float fps=25,
                                         const unsigned int nb_loops=0) {
      CImg<charT> command(1024), filename_tmp(256), filename_tmp2(256);
      CImgList<charT> filenames;

#ifdef cimg_use_png
#define _cimg_save_gif_extension "png"
#else
#define _cimg_save_gif_extension "ppm"
#endif
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_000001." _cimg_save_gif_extension,filename_tmp._data);
      } while (cimg::path_exists(filename_tmp2));
      cimglist_for(*this,l) {
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_%.6u." _cimg_save_gif_extension,filename_tmp._data,l + 1);
        CImg<charT>::string(filename_tmp2).move_to(filenames);
        CImg<T> frame;
        if (_data[l]._depth>1) _data[l].get_slice(0).move_to(frame); else frame.assign(_data[l],true);
        if (frame._spectrum>4) frame.assign(frame.get_channels(0,3),false);
        else if (frame._spectrum==1) frame.assign(frame.get_resize(-100,-100,1,3),false);
        else if (frame._spectrum==2)
          frame.assign(frame.get_resize(-100,-100,1,4).draw_image(0,0,0,2,frame.get_shared_channel(0)),false);
        frame.save(filename_tmp2);
      }
      cimg_snprintf(command,command._width,"%s -delay %u -loop %u -dispose previous",
                    cimg::imagemagick_path(),
                    (unsigned int)std::max(0.f,cimg::round(100/fps)),
                    nb_loops);
      CImg<ucharT>::string(command).move_to(filenames,0);
      cimg_snprintf(command,command._width,"\"%s\"",
                    CImg<charT>::string(filename)._system_strescape().data());
      CImg<ucharT>::string(command).move_to(filenames);
      CImg<charT> _command = filenames>'x';
      cimg_for(_command,p,char) if (!*p) *p = ' ';
      _command.back() = 0;

      if (cimg::system(_command,cimg::imagemagick_path())!=0)
        throw CImgIOException(_cimglist_instance
                              "save_gif_external(): Failed to save file '%s' with external command 'magick/convert'.",
                              cimglist_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimglist_instance
                              "save_gif_external(): Failed to save file '%s' with external command 'magick/convert'.",
                              cimglist_instance,
                              filename);
      cimglist_for_in(*this,1,filenames._width - 1,l) std::remove(filenames[l]);
      return *this;
    }

    //! Save the list as a YUV image sequence file.
    /**
      \param filename Filename to write data to.
      \param chroma_subsampling Type of chroma subsampling. Can be <tt>{ 420 | 422 | 444 }</tt>.
      \param is_rgb Indicates whether the RGB to YUV conversion must be done for saving.
    **/
    const CImgList<T>& save_yuv(const char *const filename=0,
                                const unsigned int chroma_subsampling=444,
                                const bool is_rgb=true) const {
      return _save_yuv(0,filename,chroma_subsampling,is_rgb);
    }

    //! Save the image sequence into a YUV file.
    /**
      \param file File to write data to.
      \param chroma_subsampling Type of chroma subsampling. Can be <tt>{ 420 | 422 | 444 }</tt>.
      \param is_rgb Indicates whether the RGB to YUV conversion must be done for saving.
    **/
    const CImgList<T>& save_yuv(std::FILE *const file,
                                const unsigned int chroma_subsampling=444,
                                const bool is_rgb=true) const {
      return _save_yuv(file,0,chroma_subsampling,is_rgb);
    }

    const CImgList<T>& _save_yuv(std::FILE *const file, const char *const filename,
                                 const unsigned int chroma_subsampling,
                                 const bool is_rgb) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save_yuv(): Specified filename is (null).",
                                    cimglist_instance);
      if (chroma_subsampling!=420 && chroma_subsampling!=422 && chroma_subsampling!=444)
        throw CImgArgumentException(_cimglist_instance
                                    "save_yuv(): Specified chroma subsampling %u is invalid, for file '%s'.",
                                    cimglist_instance,
                                    chroma_subsampling,filename?filename:"(FILE*)");
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      const unsigned int
        cfx = chroma_subsampling==420 || chroma_subsampling==422?2:1,
        cfy = chroma_subsampling==420?2:1,
        w0 = (*this)[0]._width, h0 = (*this)[0]._height,
        width0 = w0 + (w0%cfx), height0 = h0 + (h0%cfy);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      cimglist_for(*this,l) {
        const CImg<T> &frame = (*this)[l];
        cimg_forZ(frame,z) {
          CImg<ucharT> YUV;
          if (sizeof(T)==1 && !is_rgb &&
              frame._width==width0 && frame._height==height0 && frame._depth==1 && frame._spectrum==3)
            YUV.assign((unsigned char*)frame._data,width0,height0,1,3,true);
          else {
            YUV = frame.get_slice(z);
            if (YUV._width!=width0 || YUV._height!=height0) YUV.resize(width0,height0,1,-100,0);
            if (YUV._spectrum!=3) YUV.resize(-100,-100,1,3,YUV._spectrum==1?1:0);
            if (is_rgb) YUV.RGBtoYCbCr();
          }
          if (chroma_subsampling==444)
            cimg::fwrite(YUV._data,(size_t)YUV._width*YUV._height*3,nfile);
          else {
            cimg::fwrite(YUV._data,(size_t)YUV._width*YUV._height,nfile);
            CImg<ucharT> UV = YUV.get_channels(1,2);
            UV.resize(UV._width/cfx,UV._height/cfy,1,2,2);
            cimg::fwrite(UV._data,(size_t)UV._width*UV._height*2,nfile);
          }
        }
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the list as a .cimg file.
    /**
       \param filename Filename to write data to.
       \param is_compressed Indicates whether data compression must be enabled.
    **/
    const CImgList<T>& save_cimg(const char *const filename, const bool is_compressed=false) const {
      return _save_cimg(0,filename,is_compressed);
    }

    const CImgList<T>& _save_cimg(std::FILE *const file, const char *const filename, const bool is_compressed) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save_cimg(): Specified filename is (null).",
                                    cimglist_instance);
#ifndef cimg_use_zlib
      if (is_compressed)
        cimg::warn(_cimglist_instance
                   "save_cimg(): Unable to save compressed data in file '%s' unless zlib is enabled, "
                   "saving them uncompressed.",
                   cimglist_instance,
                   filename?filename:"(FILE*)");
#endif
      const char *const ptype = pixel_type(), *const etype = cimg::endianness()?"big":"little";
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const bool is_bool = ptype==cimg::type<bool>::string();
      std::fprintf(nfile,"%u %s %s_endian\n",_width,ptype,etype);

      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        std::fprintf(nfile,"%u %u %u %u",img._width,img._height,img._depth,img._spectrum);
        if (img._data) {
          CImg<T> tmp;
          if (cimg::endianness()) { tmp = img; cimg::invert_endianness(tmp._data,tmp.size()); }
          const CImg<T>& ref = cimg::endianness()?tmp:img;
          bool failed_to_compress = true;
          if (is_compressed) {
#ifdef cimg_use_zlib
            Bytef *cbuf = 0;
            uLongf csiz = 0;

            if (is_bool) { // Boolean data (bitwise)
              ulongT siz;
              const unsigned char *const buf = ref._bool2uchar(siz,false);
              csiz = siz + siz/100 + 16;
              cbuf = new Bytef[csiz];
              failed_to_compress = (bool)compress(cbuf,&csiz,(Bytef*)buf,siz);
              if (!failed_to_compress) {
                std::fprintf(nfile," #%lu\n",csiz);
                cimg::fwrite(cbuf,csiz,nfile);
              }
              delete[] buf;
            } else { // Non-boolean data
              const ulongT siz = sizeof(T)*ref.size();
              csiz = siz + siz/100 + 16;
              cbuf = new Bytef[csiz];
              failed_to_compress = (bool)compress(cbuf,&csiz,(Bytef*)ref._data,siz);
              if (!failed_to_compress) {
                std::fprintf(nfile," #%lu\n",csiz);
                cimg::fwrite(cbuf,csiz,nfile);
              }
            }
            if (failed_to_compress)
              cimg::warn(_cimglist_instance
                         "save_cimg(): Failed to save compressed data for file '%s', saving them uncompressed.",
                         cimglist_instance,
                         filename?filename:"(FILE*)");
            delete[] cbuf;
#endif
          }
          if (failed_to_compress) { // Write non-compressed
            std::fputc('\n',nfile);
            if (is_bool) { // Boolean data (bitwise)
              ulongT siz;
              const unsigned char *const buf = ref._bool2uchar(siz,false);
              cimg::fwrite(buf,siz,nfile);
              delete[] buf;
            } else cimg::fwrite(ref._data,ref.size(),nfile); // Non-boolean data
          }
        } else std::fputc('\n',nfile);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save the list as a .cimg file.
    /**
       \param file File to write data to.
       \param is_compressed Indicates whether data compression must be enabled.
    **/
    const CImgList<T>& save_cimg(std::FILE *file, const bool is_compressed=false) const {
      return _save_cimg(file,0,is_compressed);
    }

    const CImgList<T>& _save_cimg(std::FILE *const file, const char *const filename,
                                 const unsigned int n0,
                                 const unsigned int x0, const unsigned int y0,
                                 const unsigned int z0, const unsigned int c0) const {
#define _cimg_save_cimg_case(Ts1,Ts2,Ts3,Tss) \
      if (!saved && ((Ts1 && !cimg::strcasecmp(Ts1,str_pixeltype)) || \
                     (Ts2 && !cimg::strcasecmp(Ts2,str_pixeltype)) || \
                     (Ts3 && !cimg::strcasecmp(Ts3,str_pixeltype)))) { \
        for (unsigned int l = 0; l<lmax; ++l) { \
          j = 0; while ((i=std::fgetc(nfile))!='\n' && i!=EOF && j<255) tmp[j++]=(char)i; tmp[j] = 0; \
          W = H = D = C = 0; \
          if (cimg_sscanf(tmp._data,"%u %u %u %u",&W,&H,&D,&C)!=4) \
            throw CImgIOException(_cimglist_instance \
                                  "save_cimg(): Invalid size (%u,%u,%u,%u) of image[%u], for file '%s'.", \
                                  cimglist_instance, \
                                  W,H,D,C,l,filename?filename:"(FILE*)"); \
          if (W*H*D*C>0) { \
            if (l<n0 || x0>=W || y0>=H || z0>=D || c0>=D) cimg::fseek(nfile,W*H*D*C*sizeof(Tss),SEEK_CUR); \
            else { \
              const CImg<T>& img = (*this)[l - n0]; \
              const T *ptrs = img._data; \
              const unsigned int \
                x1 = x0 + img._width - 1, \
                y1 = y0 + img._height - 1, \
                z1 = z0 + img._depth - 1, \
                c1 = c0 + img._spectrum - 1, \
                nx1 = x1>=W?W - 1:x1, \
                ny1 = y1>=H?H - 1:y1, \
                nz1 = z1>=D?D - 1:z1, \
                nc1 = c1>=C?C - 1:c1; \
              CImg<Tss> raw(1 + nx1 - x0); \
              const unsigned int skipvb = c0*W*H*D*sizeof(Tss); \
              if (skipvb) cimg::fseek(nfile,skipvb,SEEK_CUR); \
              for (unsigned int v = 1 + nc1 - c0; v; --v) { \
                const unsigned int skipzb = z0*W*H*sizeof(Tss); \
                if (skipzb) cimg::fseek(nfile,skipzb,SEEK_CUR); \
                for (unsigned int z = 1 + nz1 - z0; z; --z) { \
                  const unsigned int skipyb = y0*W*sizeof(Tss); \
                  if (skipyb) cimg::fseek(nfile,skipyb,SEEK_CUR); \
                  for (unsigned int y = 1 + ny1 - y0; y; --y) { \
                    const unsigned int skipxb = x0*sizeof(Tss); \
                    if (skipxb) cimg::fseek(nfile,skipxb,SEEK_CUR); \
                    raw.assign(ptrs, raw._width); \
                    ptrs+=img._width; \
                    if (endian) cimg::invert_endianness(raw._data,raw._width); \
                    cimg::fwrite(raw._data,raw._width,nfile); \
                    const unsigned int skipxe = (W - 1 - nx1)*sizeof(Tss); \
                    if (skipxe) cimg::fseek(nfile,skipxe,SEEK_CUR); \
                  } \
                  const unsigned int skipye = (H - 1 - ny1)*W*sizeof(Tss); \
                  if (skipye) cimg::fseek(nfile,skipye,SEEK_CUR); \
                } \
                const unsigned int skipze = (D - 1 - nz1)*W*H*sizeof(Tss); \
                if (skipze) cimg::fseek(nfile,skipze,SEEK_CUR); \
              } \
              const unsigned int skipve = (C - 1 - nc1)*W*H*D*sizeof(Tss); \
              if (skipve) cimg::fseek(nfile,skipve,SEEK_CUR); \
            } \
          } \
        } \
        saved = true; \
      }

      if (!file && !filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save_cimg(): Specified filename is (null).",
                                    cimglist_instance);
      if (is_empty())
        throw CImgInstanceException(_cimglist_instance
                                    "save_cimg(): Empty instance, for file '%s'.",
                                    cimglist_instance,
                                    filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb+");
      bool saved = false, endian = cimg::endianness();
      CImg<charT> tmp(256), str_pixeltype(256), str_endian(256);
      *tmp = *str_pixeltype = *str_endian = 0;
      unsigned int j, N, W, H, D, C;
      int i, err;
      j = 0; while ((i=std::fgetc(nfile))!='\n' && i!=EOF && j<256) tmp[j++] = (char)i; tmp[j] = 0;
      err = cimg_sscanf(tmp._data,"%u%*c%255[A-Za-z123468_]%*c%255[sA-Za-z_ ]",&N,str_pixeltype._data,str_endian._data);
      if (err<2) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "save_cimg(): CImg header not found in file '%s'.",
                              cimglist_instance,
                              filename?filename:"(FILE*)");
      }
      if (!cimg::strncasecmp("little",str_endian,6)) endian = false;
      else if (!cimg::strncasecmp("big",str_endian,3)) endian = true;
      const unsigned int lmax = std::min(N,n0 + _width);
      _cimg_save_cimg_case("bool",0,0,cimg_uint8);
      _cimg_save_cimg_case("uint8","unsigned_char","uchar",cimg_uint8);
      _cimg_save_cimg_case("int8",0,0,cimg_int8);
      _cimg_save_cimg_case("char",0,0,char);
      _cimg_save_cimg_case("uint16","unsigned_short","ushort",cimg_uint16);
      _cimg_save_cimg_case("int16","short",0,cimg_int16);
      _cimg_save_cimg_case("uint32","unsigned_int","uint",cimg_uint32);
      _cimg_save_cimg_case("int32","int",0,cimg_int32);
      _cimg_save_cimg_case("uint64","unsigned_int64",0,cimg_uint64);
      _cimg_save_cimg_case("int64",0,0,cimg_int64);
      _cimg_save_cimg_case("float","float32",0,cimg_float32);
      _cimg_save_cimg_case("float64","double",0,cimg_float64);

      if (!saved) {
        if (!file) cimg::fclose(nfile);
        throw CImgIOException(_cimglist_instance
                              "save_cimg(): Unsupported data type '%s' for file '%s'.",
                              cimglist_instance,
                              filename?filename:"(FILE*)",str_pixeltype._data);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Insert the image list instance into an existing .cimg file, at specified coordinates.
    /**
      \param filename Filename to write data to.
      \param n0 Starting index of images to write.
      \param x0 Starting X-coordinates of image regions to write.
      \param y0 Starting Y-coordinates of image regions to write.
      \param z0 Starting Z-coordinates of image regions to write.
      \param c0 Starting C-coordinates of image regions to write.
    **/
    const CImgList<T>& save_cimg(const char *const filename,
                                 const unsigned int n0,
                                 const unsigned int x0, const unsigned int y0,
                                 const unsigned int z0, const unsigned int c0) const {
      return _save_cimg(0,filename,n0,x0,y0,z0,c0);
    }

    //! Insert the image list instance into an existing .cimg file, at specified coordinates.
    /**
      \param file File to write data to.
      \param n0 Starting index of images to write.
      \param x0 Starting X-coordinates of image regions to write.
      \param y0 Starting Y-coordinates of image regions to write.
      \param z0 Starting Z-coordinates of image regions to write.
      \param c0 Starting C-coordinates of image regions to write.
    **/
    const CImgList<T>& save_cimg(std::FILE *const file,
                                 const unsigned int n0,
                                 const unsigned int x0, const unsigned int y0,
                                 const unsigned int z0, const unsigned int c0) const {
      return _save_cimg(file,0,n0,x0,y0,z0,c0);
    }

    static void _save_empty_cimg(std::FILE *const file, const char *const filename,
                                const unsigned int nb,
                                const unsigned int dx, const unsigned int dy,
                                const unsigned int dz, const unsigned int dc) {
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const ulongT siz = (ulongT)dx*dy*dz*dc*sizeof(T);
      std::fprintf(nfile,"%u %s\n",nb,pixel_type());
      for (unsigned int i=nb; i; --i) {
        std::fprintf(nfile,"%u %u %u %u\n",dx,dy,dz,dc);
        for (ulongT off = siz; off; --off) std::fputc(0,nfile);
      }
      if (!file) cimg::fclose(nfile);
    }

    //! Save an empty (non-compressed) .cimg file with specified dimensions.
    /**
        \param filename Filename to write data to.
        \param nb Number of images to write.
        \param dx Width of images in the written file.
        \param dy Height of images in the written file.
        \param dz Depth of images in the written file.
        \param dc Spectrum of images in the written file.
    **/
    static void save_empty_cimg(const char *const filename,
                                const unsigned int nb,
                                const unsigned int dx, const unsigned int dy=1,
                                const unsigned int dz=1, const unsigned int dc=1) {
      return _save_empty_cimg(0,filename,nb,dx,dy,dz,dc);
    }

    //! Save an empty .cimg file with specified dimensions.
    /**
        \param file File to write data to.
        \param nb Number of images to write.
        \param dx Width of images in the written file.
        \param dy Height of images in the written file.
        \param dz Depth of images in the written file.
        \param dc Spectrum of images in the written file.
    **/
    static void save_empty_cimg(std::FILE *const file,
                                const unsigned int nb,
                                const unsigned int dx, const unsigned int dy=1,
                                const unsigned int dz=1, const unsigned int dc=1) {
      return _save_empty_cimg(file,0,nb,dx,dy,dz,dc);
    }

    //! Save the list as a TIFF file.
    /**
      \param filename Filename to write data to.
      \param compression_type Compression mode used to write data.
      \param voxel_size Voxel size, to be stored in the file metadata.
      \param description Description, to be stored in the file metadata.
      \param use_bigtiff Indicates whether the file is saved as BigTIFF (>4 GB) or not.
    **/
    const CImgList<T>& save_tiff(const char *const filename, const unsigned int compression_type=0,
                                 const float *const voxel_size=0, const char *const description=0,
                                 const bool use_bigtiff=true) const {
      if (!filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save_tiff(): Specified filename is (null).",
                                    cimglist_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

#ifndef cimg_use_tiff
      if (_width==1) _data[0].save_tiff(filename,compression_type,voxel_size,description,use_bigtiff);
      else cimglist_for(*this,l) {
          CImg<charT> nfilename(1024);
          cimg::number_filename(filename,l,6,nfilename);
          _data[l].save_tiff(nfilename,compression_type,voxel_size,description,use_bigtiff);
        }
#else
      ulongT siz = 0;
      cimglist_for(*this,l) siz+=_data[l].size();
      const bool _use_bigtiff = use_bigtiff && sizeof(siz)>=8 && siz*sizeof(T)>=1UL<<31; // No bigtiff for small images
      TIFF *tif = TIFFOpen(filename,_use_bigtiff?"w8":"w4");
      if (tif) {
        double val_min = cimg::type<double>::inf(), val_max = -val_min;
        cimglist_for(*this,l) {
          double l_val_min, l_val_max = (double)_data[l].max_min(l_val_min);
          if (l_val_min<val_min) val_min = l_val_min;
          if (l_val_max>val_max) val_max = l_val_max;
        }
        for (unsigned int dir = 0, l = 0; l<_width; ++l) {
          const CImg<T>& img = (*this)[l];
          cimg_forZ(img,z) img._save_tiff(tif,dir++,z,compression_type,voxel_size,description,val_min,val_max);
        }
        TIFFClose(tif);
      } else
        throw CImgIOException(_cimglist_instance
                              "save_tiff(): Failed to open stream for file '%s'.",
                              cimglist_instance,
                              filename);
#endif
      return *this;
    }

    //! Save the list as a gzipped file using the external tool 'gzip'.
    /**
      \param filename Filename to write data to.
    **/
    const CImgList<T>& save_gzip_external(const char *const filename) const {
      if (!filename)
        throw CImgIOException(_cimglist_instance
                              "save_gzip_external(): Specified filename is (null).",
                              cimglist_instance);
      CImg<charT> command(1024), filename_tmp(256), body(256);
      const char
        *ext = cimg::split_filename(filename,body),
        *ext2 = cimg::split_filename(body,0);
      do {
        if (!cimg::strcasecmp(ext,"gz")) {
          if (*ext2) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                   cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext2);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        } else {
          if (*ext) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                  cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        }
      } while (cimg::path_exists(filename_tmp));

      if (is_saveable(body)) {
        save(filename_tmp);
        cimg_snprintf(command,command._width,"\"%s\" -c \"%s\" > \"%s\"",
                      cimg::gzip_path(),
                      CImg<charT>::string(filename_tmp)._system_strescape().data(),
                      CImg<charT>::string(filename)._system_strescape().data());
        if (cimg::system(command,cimg::gzip_path())!=0)
          throw CImgIOException(_cimglist_instance
                                "save_gzip_external(): Failed to save file '%s' with external command 'gzip'.",
                                cimglist_instance,
                                filename);
        if (!cimg::path_exists(filename))
          throw CImgIOException(_cimglist_instance
                                "save_gzip_external(): Failed to save file '%s' with external command 'gzip'.",
                                cimglist_instance,
                                filename);
        std::remove(filename_tmp);
      } else {
        CImg<charT> nfilename(1024);
        cimglist_for(*this,l) {
          cimg::number_filename(body,l,6,nfilename);
          if (*ext) cimg_snprintf(nfilename._data + std::strlen(nfilename),64,".%s",ext);
          _data[l].save_gzip_external(nfilename);
        }
      }
      return *this;
    }

    //! Save the image sequence (using the OpenCV library when available).
    /**
       \param filename Filename to write data to.
       \param fps Number of frames per second.
       \param codec Type of compression (See http://www.fourcc.org/codecs.php to see available codecs).
       \param keep_open Indicates whether the video writer associated with the specified filename
       must be kept open (to allow frames to be added in the same file afterwards).
    **/
    const CImgList<T>& save_video(const char *const filename, const unsigned int fps=25,
                                  const char *codec=0, const bool keep_open=false) const {
#ifndef cimg_use_opencv
      cimg::unused(codec,keep_open);
      if (keep_open) cimg::warn(_cimglist_instance
                                "save_video(): Cannot output streamed video, as this requires features from the "
                                "OpenCV library ('-Dcimg_use_opencv') must be defined).",
                                cimglist_instance);
      if (!is_empty()) return save_ffmpeg_external(filename,fps);
      return *this;
#else
      try {
        static cv::VideoWriter *writers[32] = {};
        static CImgList<charT> filenames(32);
        static CImg<intT> sizes(32,2,1,1,0);
        static int last_used_index = -1;

        // Detect if a video writer already exists for the specified filename.
        cimg::mutex(9);
        int index = -1;
        if (filename) {
          if (last_used_index>=0 && !std::strcmp(filename,filenames[last_used_index])) {
            index = last_used_index;
          } else cimglist_for(filenames,l) if (filenames[l] && !std::strcmp(filename,filenames[l])) {
              index = l; break;
            }
        } else index = last_used_index;
        cimg::mutex(9,0);

        // Find empty slot for capturing video stream.
        if (index<0) {
          if (!filename)
            throw CImgArgumentException(_cimglist_instance
                                        "save_video(): No already open video writer found. You must specify a "
                                        "non-(null) filename argument for the first call.",
                                        cimglist_instance);
          else { cimg::mutex(9); cimglist_for(filenames,l) if (!filenames[l]) { index = l; break; } cimg::mutex(9,0); }
          if (index<0)
            throw CImgIOException(_cimglist_instance
                                  "save_video(): File '%s', no video writer slots available. "
                                  "You have to release some of your previously opened videos.",
                                  cimglist_instance,filename);
          if (is_empty())
            throw CImgInstanceException(_cimglist_instance
                                        "save_video(): Instance list is empty.",
                                        cimglist_instance);
          const unsigned int W = _data?_data[0]._width:0, H = _data?_data[0]._height:0;
          if (!W || !H)
            throw CImgInstanceException(_cimglist_instance
                                        "save_video(): Frame [0] is an empty image.",
                                        cimglist_instance);
          const char
            *const _codec = codec && *codec?codec:"h264",
            codec0 = cimg::uppercase(_codec[0]),
            codec1 = _codec[0]?cimg::uppercase(_codec[1]):0,
            codec2 = _codec[1]?cimg::uppercase(_codec[2]):0,
            codec3 = _codec[2]?cimg::uppercase(_codec[3]):0;
          cimg::mutex(9);
          writers[index] = new cv::VideoWriter(filename,_cimg_fourcc(codec0,codec1,codec2,codec3),fps,cv::Size(W,H));
          if (!writers[index]->isOpened()) {
            delete writers[index];
            writers[index] = 0;
            cimg::mutex(9,0);
            throw CImgIOException(_cimglist_instance
                                  "save_video(): File '%s', unable to initialize video writer with codec '%s'.",
                                  cimglist_instance,filename,
                                  _codec);
          }
          CImg<charT>::string(filename).move_to(filenames[index]);
          sizes(index,0) = W;
          sizes(index,1) = H;
          cimg::mutex(9,0);
        }

        if (!is_empty()) {
          const unsigned int W = sizes(index,0), H = sizes(index,1);
          cimg::mutex(9);
          cimglist_for(*this,l) {
            CImg<T> &src = _data[l];
            if (src.is_empty())
              cimg::warn(_cimglist_instance
                         "save_video(): Skip empty frame %d for file '%s'.",
                         cimglist_instance,l,filename);
            if (src._spectrum>3)
              cimg::warn(_cimglist_instance
                         "save_video(): Frame %u has incompatible dimension (%u,%u,%u,%u). "
                         "Some image data may be ignored when writing frame into video file '%s'.",
                         cimglist_instance,l,src._width,src._height,src._depth,src._spectrum,filename);
            cimg_forZ(src,z) {
              CImg<T> _src = src._depth>1?src.get_slice(z):src.get_shared();
              if (_src._width==W && _src._height==H && _src._spectrum==3)
                writers[index]->write(CImg<ucharT>(_src)._cimg2cvmat());
              else {
                CImg<ucharT> __src(_src,false);
                __src.channels(0,std::min(__src._spectrum - 1,2U)).resize(W,H);
                __src.resize(W,H,1,3,__src._spectrum==1);
                writers[index]->write(__src._cimg2cvmat());
              }
            }
          }
          cimg::mutex(9,0);
        }

        cimg::mutex(9);
        if (!keep_open) {
          delete writers[index];
          writers[index] = 0;
          filenames[index].assign();
          sizes(index,0) = sizes(index,1) = 0;
          last_used_index = -1;
        } else last_used_index = index;
        cimg::mutex(9,0);
      } catch (CImgIOException &e) {
        if (!keep_open) return save_ffmpeg_external(filename,fps);
        throw e;
      }
      return *this;
#endif
    }

    //! Save the image sequence, using the external tool 'ffmpeg'.
    /**
      \param filename Filename to write data to.
      \param fps Number of frames per second.
      \param codec Type of compression.
      \param bitrate Output bitrate
    **/
    const CImgList<T>& save_ffmpeg_external(const char *const filename, const unsigned int fps=25,
                                            const char *const codec=0, const unsigned int bitrate=2048) const {
      if (!filename)
        throw CImgArgumentException(_cimglist_instance
                                    "save_ffmpeg_external(): Specified filename is (null).",
                                    cimglist_instance);
      if (is_empty()) { cimg::fempty(0,filename); return *this; }

      const char
        *const ext = cimg::split_filename(filename),
        *const _codec = codec?codec:
        !cimg::strcasecmp(ext,"flv")?"flv":
        !cimg::strcasecmp(ext,"mp4")?"h264":"mpeg2video";

      CImg<charT> command(1024), filename_tmp(256), filename_tmp2(256);
      CImgList<charT> filenames;
      cimglist_for(*this,l) if (!_data[l].is_sameXYZ(_data[0]))
        throw CImgInstanceException(_cimglist_instance
                                    "save_ffmpeg_external(): Invalid instance dimensions for file '%s'.",
                                    cimglist_instance,
                                    filename);
      do {
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand());
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_000001.ppm",filename_tmp._data);
      } while (cimg::path_exists(filename_tmp2));
      unsigned int frame = 1;
      cimglist_for(*this,l) {
        CImg<T>& src = _data[l];
        cimg_forZ(src,z) {
          cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_%.6u.ppm",filename_tmp._data,frame);
          CImg<charT>::string(filename_tmp2).move_to(filenames);
          CImg<T> _src = src._depth>1?src.get_slice(z):src.get_shared();
          if (_src._width%2 || _src._height%2) // Force output to have an even number of columns and rows
            _src.assign(_src.get_resize(_src._width + (_src._width%2),_src._height + (_src._height%2),1,-100,0),false);
          if (_src._spectrum!=3) // Force output to be one slice, in color
            _src.assign(_src.get_resize(-100,-100,1,3),false);
          _src.save_pnm(filename_tmp2);
          ++frame;
        }
      }
      cimg_snprintf(command,command._width,
                    "\"%s\" -framerate %u -v -8 -y -i \"%s_%%6d.ppm\" -pix_fmt yuv420p -vcodec %s -b %uk -r %u \"%s\"",
                    cimg::ffmpeg_path(),
                    fps,CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    _codec,bitrate,fps,
                    CImg<charT>::string(filename)._system_strescape().data());
      if (cimg::system(command,cimg::ffmpeg_path())!=0)
        throw CImgIOException(_cimglist_instance
                              "save_ffmpeg_external(): Failed to save file '%s' with external command 'ffmpeg'.",
                              cimglist_instance,
                              filename);
      if (!cimg::path_exists(filename))
        throw CImgIOException(_cimglist_instance
                              "save_ffmpeg_external(): Failed to save file '%s' with external command 'ffmpeg'.",
                              cimglist_instance,
                              filename);
      cimglist_for(*this,l) std::remove(filenames[l]);
      return *this;
    }

    //! Serialize a CImgList<T> instance into a raw CImg<unsigned char> buffer.
    /**
       \param is_compressed Indicates that zlib compression must be used for serialization
       (this requires 'cimg_use_zlib' been enabled).
       \param header_size Reserve empty bytes as a starting header.
    **/
    CImg<ucharT> get_serialize(const bool is_compressed=false, const unsigned int header_size=0) const {
#ifndef cimg_use_zlib
      if (is_compressed)
        cimg::warn(_cimglist_instance
                   "get_serialize(): Unable to compress data unless zlib is enabled, "
                   "storing them uncompressed.",
                   cimglist_instance);
#endif
      CImgList<ucharT> stream;
      if (header_size) CImg<ucharT>(1,header_size,1,1,0).move_to(stream);
      CImg<charT> tmpstr(128);
      const char *const ptype = pixel_type(), *const etype = cimg::endianness()?"big":"little";
      cimg_snprintf(tmpstr,tmpstr._width,"%u %s %s_endian\n",_width,ptype,etype);
      CImg<ucharT>::string(tmpstr,false).move_to(stream);
      cimglist_for(*this,l) {
        const CImg<T>& img = _data[l];
        cimg_snprintf(tmpstr,tmpstr._width,"%u %u %u %u",img._width,img._height,img._depth,img._spectrum);
        CImg<ucharT>::string(tmpstr,false).move_to(stream);
        if (img._data) {
          CImg<T> tmp;
          if (cimg::endianness()) { tmp = img; cimg::invert_endianness(tmp._data,tmp.size()); }
          const CImg<T>& ref = cimg::endianness()?tmp:img;
          bool failed_to_compress = true;
          if (is_compressed) {
#ifdef cimg_use_zlib
            const ulongT siz = sizeof(T)*ref.size();
            uLongf csiz = (ulongT)compressBound(siz);
            Bytef *const cbuf = new Bytef[csiz];
            if (compress(cbuf,&csiz,(Bytef*)ref._data,siz))
              cimg::warn(_cimglist_instance
                         "get_serialize(): Failed to save compressed data, saving them uncompressed.",
                         cimglist_instance);
            else {
              cimg_snprintf(tmpstr,tmpstr._width," #%lu\n",csiz);
              CImg<ucharT>::string(tmpstr,false).move_to(stream);
              CImg<ucharT>(cbuf,csiz).move_to(stream);
              delete[] cbuf;
              failed_to_compress = false;
            }
#endif
          }
          if (failed_to_compress) { // Write in a non-compressed way
            CImg<charT>::string("\n",false).move_to(stream);
            stream.insert(1);
            stream.back().
              assign((unsigned char*)ref._data,ref._width,ref._height,ref._depth,ref._spectrum*sizeof(T),true);
          }
        } else CImg<charT>::string("\n",false).move_to(stream);
      }

      // Determine best serialized image dimensions to store the whole buffer.
      ulongT siz = 0;
      cimglist_for(stream,l) siz+=stream[l].size();
      const ulongT max_siz = (ulongT)cimg::type<int>::max();
      const unsigned int
        nw = (unsigned int)(siz/max_siz + ((siz%max_siz)?1:0)),
        nh = (unsigned int)(siz/nw + (siz%nw?1:0));
      CImg<ucharT> res(nw,nh,1,1,0);
      unsigned char *ptr = res.data();
      cimglist_for(stream,l) { siz = stream[l].size(); std::memcpy(ptr,stream[l]._data,siz); ptr+=siz; }
      return res;
    }

    //! Unserialize a CImg<unsigned char> serialized buffer into a CImgList<T> list.
    template<typename t>
    static CImgList<T> get_unserialize(const CImg<t>& buffer, const unsigned int header_size=0) {
#ifdef cimg_use_zlib
#define _cimgz_unserialize_case(Tss) { \
        Bytef *cbuf = 0; \
        if (sizeof(t)!=1 || buffer.pixel_type()==cimg::type<bool>::string()) { \
          cbuf = new Bytef[csiz]; Bytef *_cbuf = cbuf; \
          for (ulongT k = 0; k<csiz && stream<estream; ++k) *(_cbuf++) = (Bytef)*(stream++); \
          is_bytef = false; \
        } else { cbuf = (Bytef*)stream; stream+=csiz; is_bytef = true; } \
        raw.assign(W,H,D,C); \
        uLongf destlen = raw.size()*sizeof(Tss); \
        uncompress((Bytef*)raw._data,&destlen,cbuf,csiz); \
        if (!is_bytef) delete[] cbuf; \
      }
#else
#define _cimgz_unserialize_case(Tss) \
      throw CImgArgumentException("CImgList<%s>::get_unserialize(): Unable to unserialize compressed data " \
                                  "unless zlib is enabled.", \
                                  pixel_type());
#endif

#define _cimg_unserialize_case(Ts1,Ts2,Ts3,Tss) \
      if (!loaded && ((Ts1 && !cimg::strcasecmp(Ts1,str_pixeltype)) || \
                      (Ts2 && !cimg::strcasecmp(Ts2,str_pixeltype)) || \
                      (Ts3 && !cimg::strcasecmp(Ts3,str_pixeltype)))) { \
        for (unsigned int l = 0; l<N; ++l) { \
          j = 0; while ((i=(int)*stream)!='\n' && stream<estream && j<255) { ++stream; tmp[j++] = (char)i; } \
          ++stream; tmp[j] = 0; \
          W = H = D = C = 0; csiz = 0; \
          if ((err = cimg_sscanf(tmp._data,"%u %u %u %u #" cimg_fuint64,&W,&H,&D,&C,&csiz))<4) \
            throw CImgArgumentException("CImgList<%s>::unserialize(): Invalid specified size (%u,%u,%u,%u) for " \
                                        "image #%u in serialized buffer.", \
                                        pixel_type(),W,H,D,C,l); \
          if (W*H*D*C>0) { \
            CImg<Tss> raw; \
            CImg<T> &img = res._data[l]; \
            if (err==5) _cimgz_unserialize_case(Tss) \
            else { \
              raw.assign(W,H,D,C); \
              CImg<ucharT> _raw((unsigned char*)raw._data,W*sizeof(Tss),H,D,C,true); \
              if (sizeof(t)==1) { std::memcpy(_raw,stream,_raw.size()); stream+=_raw.size(); } \
              else cimg_for(_raw,p,unsigned char) *p = (unsigned char)*(stream++); \
            } \
            if (endian!=cimg::endianness()) cimg::invert_endianness(raw._data,raw.size()); \
            raw.move_to(img); \
          } \
        } \
        loaded = true; \
      }

      if (buffer.is_empty())
        throw CImgArgumentException("CImgList<%s>::get_unserialize(): Specified serialized buffer is (null).",
                                    pixel_type());
      CImgList<T> res;
      const t *stream = buffer._data + header_size, *const estream = buffer._data + buffer.size();
      bool loaded = false, endian = cimg::endianness(), is_bytef = false;
      CImg<charT> tmp(256), str_pixeltype(256), str_endian(256);
      *tmp = *str_pixeltype = *str_endian = 0;
      unsigned int j, N = 0, W, H, D, C;
      uint64T csiz;
      int i, err;
      cimg::unused(is_bytef);
      do {
        j = 0; while ((i=(int)*stream)!='\n' && stream<estream && j<255) { ++stream; tmp[j++] = (char)i; }
        ++stream; tmp[j] = 0;
      } while (*tmp=='#' && stream<estream);
      err = cimg_sscanf(tmp._data,"%u%*c%255[A-Za-z123468_]%*c%255[sA-Za-z_ ]",
                        &N,str_pixeltype._data,str_endian._data);
      if (err<2)
        throw CImgArgumentException("CImgList<%s>::get_unserialize(): CImg header not found in serialized buffer.",
                                    pixel_type());
      if (!cimg::strncasecmp("little",str_endian,6)) endian = false;
      else if (!cimg::strncasecmp("big",str_endian,3)) endian = true;
      res.assign(N);
      _cimg_unserialize_case("bool",0,0,cimg_uint8);
      _cimg_unserialize_case("uint8","unsigned_char","uchar",cimg_uint8);
      _cimg_unserialize_case("int8",0,0,cimg_int8);
      _cimg_unserialize_case("char",0,0,char);
      _cimg_unserialize_case("uint16","unsigned_short","ushort",cimg_uint16);
      _cimg_unserialize_case("int16","short",0,cimg_int16);
      _cimg_unserialize_case("uint32","unsigned_int","uint",cimg_uint32);
      _cimg_unserialize_case("int32","int",0,cimg_int32);
      _cimg_unserialize_case("uint64","unsigned_int64",0,cimg_uint64);
      _cimg_unserialize_case("int64",0,0,cimg_int64);
#if cimg_is_float16==1
      _cimg_unserialize_case("float16","half",0,cimg_float16);
#endif
      _cimg_unserialize_case("float32","float",0,cimg_float32);
      _cimg_unserialize_case("float64","double",0,cimg_float64);
      if (!loaded)
        throw CImgArgumentException("CImgList<%s>::get_unserialize(): Unsupported pixel type '%s' defined "
                                    "in serialized buffer.",
                                    pixel_type(),str_pixeltype._data);
      return res;
    }

    //@}
    //----------------------------------
    //
    //! \name Others
    //@{
    //----------------------------------

    //! Return a predefined CImg font with the requested height.
    /**
       \param requested_height Height of the desired font (exact match for 13,23,53,103).
       \param is_variable_width Decides if the font has a variable (\c true) or fixed (\c false) width.
       \note Beware, the returned reference is valid only until the next call to this function!
    **/
    static const CImgList<ucharT>& font(const unsigned int requested_height, const bool is_variable_width=true) {
      if (!requested_height) return CImgList<ucharT>::const_empty();
      cimg::mutex(11);
      static const unsigned char font_resizemap[] = {
        0, 4, 7, 9, 11, 13, 15, 17, 19, 21, 22, 24, 26, 27, 29, 30,
        32, 33, 35, 36, 38, 39, 41, 42, 43, 45, 46, 47, 49, 50, 51, 52,
        54, 55, 56, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 71, 72,
        73, 74, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
        90, 91, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
        107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
        123, 124, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137,
        138, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 148, 149, 150, 151,
        152, 153, 154, 155, 156, 157, 157, 158, 159, 160, 161, 162, 163, 164, 164, 165,
        166, 167, 168, 169, 170, 170, 171, 172, 173, 174, 175, 176, 176, 177, 178, 179,
        180, 181, 181, 182, 183, 184, 185, 186, 186, 187, 188, 189, 190, 191, 191, 192,
        193, 194, 195, 196, 196, 197, 198, 199, 200, 200, 201, 202, 203, 204, 205, 205,
        206, 207, 208, 209, 209, 210, 211, 212, 213, 213, 214, 215, 216, 216, 217, 218,
        219, 220, 220, 221, 222, 223, 224, 224, 225, 226, 227, 227, 228, 229, 230, 231,
        231, 232, 233, 234, 234, 235, 236, 237, 238, 238, 239, 240, 241, 241, 242, 243,
        244, 244, 245, 246, 247, 247, 248, 249, 250, 250, 251, 252, 253, 253, 254, 255 };
      static const char *const font_data[] = {
        cimg::data_font_small(),
        cimg::data_font_normal(),
        cimg::data_font_large(),
        cimg::data_font_huge() };
      static const unsigned int
        font_width[] = { 10,26,52,104 },
        font_height[] = { 13,32,64,128 },
        font_M[] = { 86,91,91,47 };
      static const unsigned char font_is_binary[] = { 1,0,0,1 };
      static CImg<ucharT> font_base[4];

      unsigned int ind =
        requested_height<=font_height[0]?0U:
        requested_height<=font_height[1]?1U:
        requested_height<=font_height[2]?2U:3U;

      // Decompress nearest base font data if needed.
      CImg<ucharT> &basef = font_base[ind];
      if (!basef) {
        basef.assign(256*font_width[ind],font_height[ind]);
        unsigned char *ptrd = basef;
        const unsigned char *const ptrde = basef.end();
        const char *dataf = font_data[ind];

        // Uncompress font data (decode RLE).
        const unsigned int M = font_M[ind];
        if (font_is_binary[ind])
          for (const char *ptrs = dataf; *ptrs; ++ptrs) {
            const int _n = (int)(*ptrs - M - 32), v = _n>=0?255:0, n = _n>=0?_n:-_n;
            if (ptrd + n<=ptrde) { std::memset(ptrd,v,n); ptrd+=n; }
            else { std::memset(ptrd,v,ptrde - ptrd); break; }
          }
        else
          for (const char *ptrs = dataf; *ptrs; ++ptrs) {
            int n = (int)*ptrs - M - 32, v = 0;
            if (n>=0) { v = 85*n; n = 1; }
            else {
              n = -n;
              v = (int)*(++ptrs) - M - 32;
              if (v<0) { v = 0; --ptrs; } else v*=85;
            }
            if (ptrd + n<=ptrde) { std::memset(ptrd,v,n); ptrd+=n; }
            else { std::memset(ptrd,v,ptrde - ptrd); break; }
          }
      }

      // Find optimal font cache location to return.
      static CImgList<ucharT> fonts[32];
      static bool is_variable_widths[32] = {};
      ind = ~0U;
      for (int i = 0; i<32; ++i)
        if (!fonts[i] || (is_variable_widths[i]==is_variable_width && requested_height==fonts[i][0]._height)) {
          ind = (unsigned int)i; break; // Found empty slot or cached font
        }
      if (ind==~0U) { // No empty slots or existing fonts in the cache
        fonts->assign();
        std::memmove((void*)fonts,(void*)(fonts + 1),31*sizeof(CImgList<ucharT>));
        std::memmove(is_variable_widths,is_variable_widths + 1,31*sizeof(bool));
        std::memset((void*)(fonts + (ind=31)),0,sizeof(CImgList<ucharT>)); // Free a cache slot for the new font
      }
      CImgList<ucharT> &font = fonts[ind];

      // Render requested font.
      if (!font) {
        is_variable_widths[ind] = is_variable_width;
        basef.get_split('x',256).move_to(font);
        if (requested_height!=font[0]._height)
          cimglist_for(font,l) {
            font[l].resize(std::max(1U,font[l]._width*requested_height/font[l]._height),requested_height,-100,-100,5);
            cimg_for(font[l],ptr,ucharT) *ptr = font_resizemap[*ptr];
          }
        if (is_variable_width) { // Crop font
          cimglist_for(font,l) {
            CImg<ucharT>& letter = font[l];
            int xmin = letter.width(), xmax = 0;
            cimg_forX(letter,x) { // Find xmin
              cimg_forY(letter,y) if (letter(x,y)) { xmin = x; break; }
              if (xmin!=letter.width()) break;
            }
            cimg_rofX(letter,x) { // Find xmax
              cimg_forY(letter,y) if (letter(x,y)) { xmax = x; break; }
              if (xmax) break;
            }
            if (xmin<=xmax) letter.crop(xmin,0,xmax,letter._height - 1);
          }
          font[(int)' '].resize(font[(int)'f']._width,-100,-100,-100,0);
          if (' ' + 256<font.size()) font[' ' + 256].resize(font[(int)'f']._width,-100,-100,-100,0);
        }
        font.insert(256,0);
        cimglist_for_in(font,0,255,l) font[l].assign(font[l + 256]._width,font[l + 256]._height,1,1,255);
      }
      cimg::mutex(11,0);
      return font;
    }

    //! Compute a 1D Fast Fourier Transform, along specified axis.
    /**
       \param axis Axis along which the Fourier transform is computed.
       \param invert Indicates whether the direct (\c false) or inverse transform (\c true) is computed.
    **/
    CImgList<T>& FFT(const char axis, const bool invert=false) {
      if (is_empty()) return *this;
      if (_width==1) insert(1);
      if (_width>2)
        cimg::warn(_cimglist_instance
                   "FFT(): Instance has more than 2 images",
                   cimglist_instance);
      CImg<T>::FFT(_data[0],_data[1],axis,invert);
      return *this;
    }

    //! Compute a 1-D Fast Fourier Transform, along specified axis \newinstance.
    CImgList<Tfloat> get_FFT(const char axis, const bool invert=false) const {
      return CImgList<Tfloat>(*this,false).FFT(axis,invert);
    }

    //! Compute n-D Fast Fourier Transform.
    /**
      \param invert Indicates whether the direct (\c false) or inverse transform (\c true) is computed.
    **/
    CImgList<T>& FFT(const bool invert=false) {
      if (is_empty()) return *this;
      if (_width==1) insert(1);
      if (_width>2)
        cimg::warn(_cimglist_instance
                   "FFT(): Instance has more than 2 images",
                   cimglist_instance);

      CImg<T>::FFT(_data[0],_data[1],invert);
      return *this;
    }

    //! Compute n-D Fast Fourier Transform \newinstance.
    CImgList<Tfloat> get_FFT(const bool invert=false) const {
      return CImgList<Tfloat>(*this,false).FFT(invert);
    }

    //! Reverse the orientations of a 3D object's primitives.
    /**
    **/
    CImgList<T>& reverse_object3d() {
      cimglist_for(*this,l) {
        CImg<T>& p = _data[l];
        switch (p.size()) {
        case 2 : case 3: cimg::swap(p[0],p[1]); break;
        case 6 : cimg::swap(p[0],p[1],p[2],p[4],p[3],p[5]); break;
        case 9 : cimg::swap(p[0],p[1],p[3],p[5],p[4],p[6]); break;
        case 4 : cimg::swap(p[0],p[1],p[2],p[3]); break;
        case 12 : cimg::swap(p[0],p[1],p[2],p[3],p[4],p[6],p[5],p[7],p[8],p[10],p[9],p[11]); break;
        }
      }
      return *this;
    }

    //! Reverse the orientations of a 3D object's primitives \newinstance.
    CImgList<T> get_reverse_object3d() const {
      return (+*this).reverse_object3d();
    }

    //@}
  }; // struct CImgList { ...

  // Completion of previously declared functions.
  //---------------------------------------------
  namespace cimg {

    // Functions to return standard streams 'stdin', 'stdout' and 'stderr'.
    // (throw a CImgIOException when macro 'cimg_use_r' is defined).
    inline FILE* _stdin(const bool throw_exception) {
#ifndef cimg_use_r
      cimg::unused(throw_exception);
      return stdin;
#else
      if (throw_exception) {
        cimg::exception_mode(0);
        throw CImgIOException("cimg::stdin(): Reference to 'stdin' stream not allowed in R mode "
                              "('cimg_use_r' is defined).");
      }
      return 0;
#endif
    }

    inline FILE* _stdout(const bool throw_exception) {
#ifndef cimg_use_r
      cimg::unused(throw_exception);
      return stdout;
#else
      if (throw_exception) {
        cimg::exception_mode(0);
        throw CImgIOException("cimg::stdout(): Reference to 'stdout' stream not allowed in R mode "
                              "('cimg_use_r' is defined).");
      }
      return 0;
#endif
    }

    inline FILE* _stderr(const bool throw_exception) {
#ifndef cimg_use_r
      cimg::unused(throw_exception);
      return stderr;
#else
      if (throw_exception) {
        cimg::exception_mode(0);
        throw CImgIOException("cimg::stderr(): Reference to 'stderr' stream not allowed in R mode "
                              "('cimg_use_r' is defined).");
      }
      return 0;
#endif
    }

    // Open a file (similar to std::fopen(), but with wide character support on Windows).
    inline std::FILE *std_fopen(const char *const path, const char *const mode) {
      std::FILE *const res = std::fopen(path,mode);
      if (res) return res;
#if cimg_OS==2
      // Try alternative method, with wide-character string.
      int err = MultiByteToWideChar(CP_UTF8,0,path,-1,0,0);
      if (err) {
        CImg<wchar_t> wpath((unsigned int)err);
        err = MultiByteToWideChar(CP_UTF8,0,path,-1,wpath,err);
        if (err) { // Convert 'mode' to a wide-character string
          err = MultiByteToWideChar(CP_UTF8,0,mode,-1,0,0);
          if (err) {
            CImg<wchar_t> wmode((unsigned int)err);
            if (MultiByteToWideChar(CP_UTF8,0,mode,-1,wmode,err))
              return _wfopen(wpath,wmode);
          }
        }
      }
#endif
      return 0;
    }

    //! Get file size.
    /**
       \param file Specified file to get size from.
       \return File size or '-1' if file does not exist.
    **/
    inline cimg_int64 fsize(std::FILE *const file) {
      cimg_int64 siz = -1;
      if (!file) return siz;

#if cimg_OS==1 // Optimized for POSIX Environments (Linux, macOS, BSD, etc.)
      const int fd = fileno(file);
      struct stat st;
      if (!fstat(fd,&st)) siz = (cimg_int64)st.st_size;
#elif cimg_OS==2 // Optimized for Windows Environements (MSVC, MinGW)
      const int fd = _fileno(file);
      siz = (cimg_int64)_filelengthi64(fd);
#endif
      // Fallback, used for non-POSIX systems or if fstat failed (pipes or sockets).
      if (siz<0) {
        const cimg_long pos = cimg::ftell(file);
        cimg::fseek(file, 0, SEEK_END);
        siz = (cimg_int64)cimg::ftell(file);
        cimg::fseek(file, pos, SEEK_SET);
      }
      return siz;
    }

    //! Get file size from filename.
    /**
       \param filename Specified filename to get size from.
       \return File size or '-1' if file does not exist.
    **/
    inline cimg_int64 fsize(const char *const filename) {
      if (!filename || !*filename) return (cimg_int64)-1;

#if cimg_OS==1 // Optimized for POSIX Environments (Linux, macOS, BSD, etc.)
      struct stat st;
      if (!stat(filename,&st)) return (cimg_int64)st.st_size;
#elif cimg_OS==2
      WIN32_FILE_ATTRIBUTE_DATA attr;
      if (win_getfileattributesEx(filename, &attr)) {
        if (!(attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) {
          LARGE_INTEGER size;
          size.HighPart = attr.nFileSizeHigh;
          size.LowPart = attr.nFileSizeLow;
          return (cimg_int64)size.QuadPart;
        }
      }
#endif
      // Fallback for other systems.
      std::FILE *const file = cimg::std_fopen(filename, "rb");
      if (!file) return (cimg_int64)-1;
      const cimg_int64 siz = cimg::fsize(file);
      cimg::fclose(file);
      return siz;
    }

    //! Display a warning message on the default output stream.
    /**
       \param format C-string containing the format of the message, as with <tt>std::printf()</tt>.
       \note If configuration macro \c cimg_strict_warnings is set, this function throws a
       \c CImgWarningException instead.
       \warning As the first argument is a format string, it is highly recommended to write
       \code
       cimg::warn("%s",warning_message);
       \endcode
       instead of
       \code
       cimg::warn(warning_message);
       \endcode
       if \c warning_message can be arbitrary, to prevent invalid memory access.
    **/
    inline void warn(const char *const format, ...) {
      if (cimg::exception_mode()>=1) {
        CImg<char> message(16384); *message = 0;
        std::va_list ap;
        va_start(ap,format);
        cimg_vsnprintf(message._data,16384,format,ap);
        va_end(ap);
#ifdef cimg_strict_warnings
        throw CImgWarningException("%s",message._data);
#else
        std::fprintf(cimg::output(),"\n%s[CImg] *** Warning ***%s%s\n",cimg::t_red(),cimg::t_normal(),message._data);
#endif
      }
    }

    //! Search path of an executable.
#if cimg_OS==2
    inline bool win_searchpath(const char *const exec_name, char *const res, const unsigned int size_res) {
      char *ptr = 0;
      DWORD err = SearchPathA(0,exec_name,0,size_res,res,&ptr);
      return err!=0;
    }
#endif

#if cimg_OS==1
    inline bool posix_searchpath(const char *file) {
      if (!file || !*file) return false;
      const char *path = std::getenv("PATH");

      if (!path) path = "/usr/local/bin:/bin:/usr/bin";
      size_t file_len = strnlen(file,NAME_MAX + 1);
      if (file_len>NAME_MAX) return false;
      size_t path_total_len = strnlen(path,PATH_MAX - 1) + 1;

      CImg<char> buf(path_total_len + file_len + 1);
      const char *p = path, *z = 0;
      while (true) {
        z = std::strchr(p,':');
        if (!z) z = p + std::strlen(p);
        if ((size_t)(z - p)>=path_total_len) {
          if (!*z++) break;
          continue;
        }
        std::memcpy(buf._data,p,z - p);
        buf[z - p] = '/';
        std::memcpy(buf._data + (z - p) + (z>p),file,file_len + 1);
        if (cimg::is_file(buf) && faccessat(AT_FDCWD,buf._data,X_OK,AT_EACCESS)==0) return true;
        if (!*z++) break;
        p = z;
      }
      return false;
    }
#endif

    //! Get the file or directory attributes with support for UTF-8 paths (Windows only).
#if cimg_OS==2
    inline DWORD win_getfileattributes(const char *const path) {
      DWORD res = GetFileAttributesA(path);
      if (res==INVALID_FILE_ATTRIBUTES) {
        // Try alternative method, with wide-character string.
        int err = MultiByteToWideChar(CP_UTF8,0,path,-1,0,0);
        if (err) {
          CImg<wchar_t> wpath((unsigned int)err);
          if (MultiByteToWideChar(CP_UTF8,0,path,-1,wpath,err)) res = GetFileAttributesW(wpath);
        }
      }
      return res;
    }

    inline BOOL win_getfileattributesEx(const char* const path, WIN32_FILE_ATTRIBUTE_DATA* attr) {
        BOOL res = GetFileAttributesExA(path,GetFileExInfoStandard,attr);
        if (!res) {
          // Try alternative method, with wide-character string.
          int err = MultiByteToWideChar(CP_UTF8,0,path,-1,0,0);
          if (err) {
            CImg<wchar_t> wpath((unsigned int)err);
            if (MultiByteToWideChar(CP_UTF8,0,path,-1,wpath,err))
              res = GetFileAttributesExW(wpath,GetFileExInfoStandard,attr);
          }
        }
        return res;
    }
#endif

    //! Get/set path to the <i>Program Files/</i> directory (Windows only).
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the program files.
    **/
#if cimg_OS==2
    inline const char* win_programfiles_path(const char *const user_path=0, const bool reinit_path=false) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(MAX_PATH);
        *s_path = 0;
        // Note: in the following line, 0x26 = CSIDL_PROGRAM_FILES (not defined on every compiler).
#if !defined(__INTEL_COMPILER)
        if (!SHGetSpecialFolderPathA(0,s_path,0x0026,false)) {
          const char *const pfPath = std::getenv("PROGRAMFILES");
          if (pfPath) {
            std::strncpy(s_path,pfPath,MAX_PATH - 1);
            s_path.back() = 0;
          }
          else std::strcpy(s_path,"C:\\PROGRA~1");
        }
#else
        std::strcpy(s_path,"C:\\PROGRA~1");
#endif
      }
      cimg::mutex(7,0);
      return s_path;
    }
#endif

    //! Get/set path to the \c curl binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c curl binary.
    **/
    inline const char *curl_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("curl.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\curl.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"curl.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./curl");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"curl");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the \c dcraw binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c dcraw binary.
    **/
    inline const char *dcraw_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("dcraw.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\dcraw.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"dcraw.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./dcraw");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"dcraw");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the FFMPEG's \c ffmpeg binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c ffmpeg binary.
    **/
    inline const char *ffmpeg_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("ffmpeg.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\ffmpeg.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"ffmpeg.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./ffmpeg");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"ffmpeg");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the GraphicsMagick's \c gm binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c gm binary.
    **/
    inline const char* graphicsmagick_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("gm.exe",s_path,s_path._width)) path_found = true;
        const char *const pf_path = win_programfiles_path();
        if (!path_found) {
          std::strcpy(s_path,".\\gm.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%.2d-\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%d-Q\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%d\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%.2d-\\VISUA~1\\BIN\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%d-Q\\VISUA~1\\BIN\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"%s\\GRAPHI~1.%d\\VISUA~1\\BIN\\gm.exe",pf_path,k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%.2d-\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%d-Q\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%d\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%.2d-\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%d-Q\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"C:\\GRAPHI~1.%d\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%.2d-\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%d-Q\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%d\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=10 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%.2d-\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 9; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%d-Q\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        for (int k = 32; k>=0 && !path_found; --k) {
          cimg_snprintf(s_path,s_path._width,"D:\\GRAPHI~1.%d\\VISUA~1\\BIN\\gm.exe",k);
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gm.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./gm");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gm");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the \c gunzip binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c gunzip binary.
    **/
    inline const char *gunzip_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("gunzip.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\gunzip.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gunzip.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./gunzip");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gunzip");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the \c gzip binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c gzip binary.
    **/
    inline const char *gzip_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("gzip.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\gzip.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gzip.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./gzip");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"gzip");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the ImageMagick's \c convert binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c convert binary.
    **/
    inline const char* imagemagick_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("magick.exe",s_path,s_path._width)) path_found = true;
        const char *const pf_path = win_programfiles_path();
        for (int l = 0; l<2 && !path_found; ++l) {
          const char *const s_exe = l?"convert":"magick";
          cimg_snprintf(s_path,s_path._width,".\\%s.exe",s_exe);
          if (cimg::is_file(s_path)) path_found = true;
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%.2d-\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%d-Q\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%d\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%.2d-\\VISUA~1\\BIN\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%d-Q\\VISUA~1\\BIN\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"%s\\IMAGEM~1.%d\\VISUA~1\\BIN\\%s.exe",pf_path,k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%.2d-\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%d-Q\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%d\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%.2d-\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%d-Q\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"C:\\IMAGEM~1.%d\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%.2d-\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%d-Q\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%d\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=10 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%.2d-\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 9; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%d-Q\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          for (int k = 32; k>=0 && !path_found; --k) {
            cimg_snprintf(s_path,s_path._width,"D:\\IMAGEM~1.%d\\VISUA~1\\BIN\\%s.exe",k,s_exe);
            if (cimg::is_file(s_path)) path_found = true;
          }
          if (!path_found) cimg_snprintf(s_path,s_path._width,"%s.exe",s_exe);
        }
#else
        std::strcpy(s_path,"./magick");
        if (cimg::is_file(s_path)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,"./convert");
          if (cimg::is_file(s_path)) path_found = true;
        }
#if cimg_OS==1
        if (!path_found) {
          std::strcpy(s_path,"magick");
          if (cimg::posix_searchpath("magick")) path_found = true;
        }
#endif
        if (!path_found) std::strcpy(s_path,"convert");
#endif
        winformat_string(s_path);

        // Put path between double quotes.
        const unsigned int siz = (unsigned int)std::strlen(s_path);
        CImg<char> s_path2(3 + siz);
        char *s = s_path2._data;
        *(s++) = '\"';
        std::memcpy(s,s_path._data,siz); s+=siz;
        *(s++) = '\"';
        *s = 0;
        s_path2.move_to(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the Medcon's \c medcon binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c medcon binary.
    **/
    inline const char* medcon_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("medcon.exe",s_path,s_path._width)) path_found = true;
        const char *const pf_path = win_programfiles_path();
        if (!path_found) {
          std::strcpy(s_path,".\\medcon.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) {
          cimg_snprintf(s_path,s_path._width,"%s\\XMedCon\\bin\\medcon.bat",pf_path);
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) {
          cimg_snprintf(s_path,s_path._width,"%s\\XMedCon\\bin\\medcon.exe",pf_path);
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) {
          std::strcpy(s_path,"C:\\XMedCon\\bin\\medcon.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"medcon.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./medcon");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"medcon");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to store temporary files.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path where temporary files can be saved.
    **/
    inline const char* temporary_path(const char *const user_path, const bool reinit_path) {
#define _cimg_test_temporary_path(p) \
      if (!path_found) { \
        cimg_snprintf(s_path,s_path._width,"%s",p); \
        cimg_snprintf(tmp,tmp._width,"%s%c%s",s_path.data(),cimg_directory_separator,filename_tmp._data); \
        if ((file=cimg::std_fopen(tmp,"wb"))!=0) { cimg::fclose(file); std::remove(tmp); path_found = true; } \
      }
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
        CImg<char> tmp(1024), filename_tmp(256);
        std::FILE *file = 0;
        cimg_snprintf(filename_tmp,filename_tmp._width,"%s.tmp",cimg::filenamerand());
        char *tmpPath = std::getenv("TMP");
        if (!tmpPath) { tmpPath = std::getenv("TEMP"); winformat_string(tmpPath); }
        if (tmpPath) _cimg_test_temporary_path(tmpPath);
#if cimg_OS==2
        _cimg_test_temporary_path("C:\\WINNT\\Temp");
        _cimg_test_temporary_path("C:\\WINDOWS\\Temp");
        _cimg_test_temporary_path("C:\\Temp");
        _cimg_test_temporary_path("C:");
        _cimg_test_temporary_path("D:\\WINNT\\Temp");
        _cimg_test_temporary_path("D:\\WINDOWS\\Temp");
        _cimg_test_temporary_path("D:\\Temp");
        _cimg_test_temporary_path("D:");
#else
        _cimg_test_temporary_path("/tmp");
        _cimg_test_temporary_path("/var/tmp");
#endif
        if (!path_found) {
          *s_path = 0;
          std::strncpy(tmp,filename_tmp,tmp._width - 1);
          tmp.back() = 0;
          if ((file=cimg::std_fopen(tmp,"wb"))!=0) { cimg::fclose(file); std::remove(tmp); path_found = true; }
        }
        if (!path_found) {
          cimg::mutex(7,0);
          throw CImgIOException("cimg::temporary_path(): Failed to locate path for writing temporary files.\n");
        }
      }
      cimg::mutex(7,0);
      return s_path;
    }

    //! Get/set path to the \c wget binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c wget binary.
    **/
    inline const char *wget_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
#if cimg_OS==2
        if (win_searchpath("wget.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\wget.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"wget.exe");
#else
        if (!path_found) {
          std::strcpy(s_path,"./wget");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"wget");
#endif
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }

#if cimg_OS==2
    //! Get/set path to the \c powershell binary.
    /**
       \param user_path Specified path, or \c 0 to get the path currently used.
       \param reinit_path Force path to be recalculated (may take some time).
       \return Path containing the \c wget binary.
    **/
    inline const char *powershell_path(const char *const user_path, const bool reinit_path) {
      static CImg<char> s_path;
      cimg::mutex(7);
      if (reinit_path) s_path.assign();
      if (user_path) {
        if (!s_path) s_path.assign(1024);
        std::strncpy(s_path,user_path,1023);
        s_path.back() = 0;
      } else if (!s_path) {
        s_path.assign(1024);
        bool path_found = false;
        if (win_searchpath("powershell.exe",s_path,s_path._width)) path_found = true;
        if (!path_found) {
          std::strcpy(s_path,".\\powershell.exe");
          if (cimg::is_file(s_path)) path_found = true;
        }
        if (!path_found) std::strcpy(s_path,"powershell.exe");
        winformat_string(s_path);
      }
      cimg::mutex(7,0);
      return s_path;
    }
#endif

    // [internal] Sorting function, used by cimg::files().
    inline int _sort_files(const void* a, const void* b) {
      const CImg<char> &sa = *(CImg<char>*)a, &sb = *(CImg<char>*)b;
      return std::strcmp(sa._data,sb._data);
    }

    //! Generate a numbered version of a filename.
    inline char* number_filename(const char *const filename, const int number,
                                 const unsigned int digits, char *const str) {
      if (!filename) { if (str) *str = 0; return 0; }
      const unsigned int siz = (unsigned int)std::strlen(filename);
      CImg<char> format(16), body(siz + 32);
      const char *const ext = cimg::split_filename(filename,body);
      if (*ext) cimg_snprintf(format,format._width,"%%s_%%.%ud.%%s",digits);
      else cimg_snprintf(format,format._width,"%%s_%%.%ud",digits);
      cimg_snprintf(str,1024,format._data,body._data,number,ext);
      return str;
    }

    //! Return the list of files/directories in specified directory.
    /**
       \param path Path to the directory. Set to 0 for current directory.
       \param is_pattern Indicates that a specified path has a matching pattern in it.
       \param mode Output type, can be primary { 0=files only | 1=folders only | 2=files + folders }.
       \param include_path Indicates that \c path must be included in resulting filenames.
       \return A list of filenames.
    **/
    inline CImgList<char> files(const char *const path, const bool is_pattern=false,
                                const unsigned int mode=2, const bool include_path=false) {
      if (!path || !*path) return files("*",true,mode,include_path);
      CImgList<char> res;

      // If path is a valid folder name, ignore argument 'is_pattern'.
      const bool _is_pattern = is_pattern && !cimg::is_directory(path);
      bool is_root = false, is_current = false;
      cimg::unused(is_root,is_current);

      // Clean format of input path.
      CImg<char> pattern, _path = CImg<char>::string(path);
#if cimg_OS==2
      for (char *ps = _path; *ps; ++ps) if (*ps=='\\') *ps='/';
#endif
      char *pd = _path;
      for (char *ps = pd; *ps; ++ps) { if (*ps!='/' || *ps!=*(ps+1)) *(pd++) = *ps; }
      *pd = 0;
      unsigned int lp = (unsigned int)std::strlen(_path);
      if (!_is_pattern && lp && _path[lp - 1]=='/') {
        _path[lp - 1] = 0; --lp;
#if cimg_OS!=2
        is_root = !*_path;
#endif
      }

      // Separate folder path and matching pattern.
      if (_is_pattern) {
        const unsigned int bpos = (unsigned int)(cimg::basename(_path,'/') - _path._data);
        CImg<char>::string(_path).move_to(pattern);
        if (bpos) {
          _path[bpos - 1] = 0; // End 'path' at last slash
#if cimg_OS!=2
          is_root = !*_path;
#endif
        } else { // No folder path specified; assuming current folder
          is_current = true; *_path = 0;
        }
        lp = (unsigned int)std::strlen(_path);
      }

      // Windows version.
#if cimg_OS==2
      if (!_is_pattern) {
        pattern.assign(lp + 3);
        std::memcpy(pattern,_path,lp);
        pattern[lp] = '/'; pattern[lp + 1] = '*'; pattern[lp + 2] = 0;
      }
      WIN32_FIND_DATAA file_data;
      const HANDLE dir = FindFirstFileA(pattern.data(),&file_data);
      if (dir==INVALID_HANDLE_VALUE) return CImgList<char>::const_empty();
      do {
        const char *const filename = file_data.cFileName;
        if (*filename!='.' || (filename[1] && (filename[1]!='.' || filename[2]))) {
          const unsigned int lf = (unsigned int)std::strlen(filename);
          const bool is_directory = (file_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)!=0;
          if ((!mode && !is_directory) || (mode==1 && is_directory) || mode>=2) {
            if (include_path) {
              CImg<char> full_filename((lp?lp+1:0) + lf + 1);
              if (lp) { std::memcpy(full_filename,_path,lp); full_filename[lp] = '/'; }
              std::memcpy(full_filename._data + (lp?lp + 1:0),filename,lf + 1);
              full_filename.move_to(res);
            } else CImg<char>(filename,lf + 1).move_to(res);
          }
        }
      } while (FindNextFileA(dir,&file_data));
      FindClose(dir);

      // Unix version (posix).
#elif cimg_OS==1
      DIR *const dir = opendir(is_root?"/":is_current?".":_path.data());
      if (!dir) return CImgList<char>::const_empty();
      struct dirent *ent;
      while ((ent=readdir(dir))!=0) {
        const char *const filename = ent->d_name;
        if (*filename!='.' || (filename[1] && (filename[1]!='.' || filename[2]))) {
          const unsigned int lf = (unsigned int)std::strlen(filename);
          CImg<char> full_filename(lp + lf + 2);

          if (!is_current) {
            full_filename.assign(lp + lf + 2);
            if (lp) std::memcpy(full_filename,_path,lp);
            full_filename[lp] = '/';
            std::memcpy(full_filename._data + lp + 1,filename,lf + 1);
          } else full_filename.assign(filename,lf + 1);

          struct stat st;
          if (stat(full_filename,&st)==-1) continue;
          const bool is_directory = (st.st_mode & S_IFDIR)!=0;
          if ((!mode && !is_directory) || (mode==1 && is_directory) || mode==2) {
            if (include_path) {
              if (!_is_pattern || (_is_pattern && !fnmatch(pattern,full_filename,0)))
                full_filename.move_to(res);
            } else {
              if (!_is_pattern || (_is_pattern && !fnmatch(pattern,full_filename,0)))
                CImg<char>(filename,lf + 1).move_to(res);
            }
          }
        }
      }
      closedir(dir);
#endif

      // Sort resulting list by lexicographic order.
      if (res._width>=2) std::qsort(res._data,res._width,sizeof(CImg<char>),_sort_files);
      return res;
    }

    inline void _create_directory(const char *const dirname, const bool force_overwrite) {
      bool is_error = false;
      if (cimg::is_directory(dirname)) return;
      if (cimg::is_file(dirname)) { // In case 'dirname' is already an existing filename
        if (!force_overwrite) is_error = true;
        else {
#if cimg_OS==2
          is_error = !DeleteFileA(dirname);
#elif cimg_OS==1
          is_error = (bool)std::remove(dirname);
#endif
        }
      }
      if (!is_error) {
#if cimg_OS==2
        if (!CreateDirectoryA(dirname,0)) {
          // The path may be UTF-8, convert it to a wide-character string and try again.
          const int wideLength = MultiByteToWideChar(CP_UTF8,0,dirname,-1,0,0);
          if (!wideLength) is_error = true;
          else {
            CImg<wchar_t> wpath(wideLength);
            if (!MultiByteToWideChar(CP_UTF8,0,dirname,-1,wpath,wideLength)) is_error = true;
            else {
              DeleteFileW(wpath);
              is_error = !CreateDirectoryW(wpath,0);
            }
          }
        }
#elif cimg_OS==1
        is_error = (bool)mkdir(dirname,0777);
#endif
      }
      if (is_error)
        throw CImgIOException("cimg::create_dir(): Failed to create directory '%s'.",dirname);
    }

    //! Create a directory.
    /**
       \param dirname The path of the directory to create.
       \param force_overwrite Force overwrite of the directory when necessary.
    **/
    inline void create_directory(const char *const dirname, const bool force_overwrite) {
#if cimg_OS==2
      const char *const cs = "/\\";
#else
      const char *const cs = "/";
#endif
      const char *ptr0 = dirname, *ptr1 = std::strpbrk(ptr0,cs);
      if (ptr1) {
        while (ptr1) { // Manage case where 'dirname' is a path with separators (multiple directories)
          if (ptr1!=ptr0) {
            CImg<char> subdir(dirname,ptr1 - dirname + 1);
            subdir.back() = 0;
            _create_directory(subdir,force_overwrite);
          }
          ptr0 = ++ptr1;
          ptr1 = std::strpbrk(ptr0,cs);
        }
#if cimg_OS==2
        const bool cond = *ptr0!='/' && *ptr0!='\\';
#else
        const bool cond = *ptr0!='/';
#endif
        if (*ptr0 && cond) _create_directory(dirname,force_overwrite);
      } else _create_directory(dirname,force_overwrite);
    }

    //! Try to guess format from an image file.
    /**
       \param file Input file (can be \c 0 if \c filename is set).
       \param filename Filename, as a C-string (can be \c 0 if \c file is set).
       \return C-string containing the guessed file format, or \c 0 if nothing has been guessed.
    **/
    inline const char *ftype(std::FILE *const file, const char *const filename) {
      if (!file && !filename)
        throw CImgArgumentException("cimg::ftype(): Specified filename is (null).");
      static const char
        *const _bmp = "bmp",
        *const _cr2 = "cr2",
        *const _dcm = "dcm",
        *const _gif = "gif",
        *const _heif = "heif",
        *const _inr = "inr",
        *const _jpg = "jpg",
        *const _off = "off",
        *const _pan = "pan",
        *const _pfm = "pfm",
        *const _png = "png",
        *const _pnm = "pnm",
        *const _tif = "tif",
        *const _webp = "webp",
        *const _jxl = "jxl";

      const char *f_type = 0;
      CImg<char> header;
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      try {
        header._load_raw(file,filename,512,1,1,1,false,false,0);
        const unsigned char *const uheader = (unsigned char*)header._data;
        if (!std::strncmp(header,"OFF\n",4)) f_type = _off; // OFF
        else if (!std::strncmp(header,"#INRIMAGE",9)) // INRIMAGE
          f_type = _inr;
        else if (!std::strncmp(header,"PANDORE",7)) // PANDORE
          f_type = _pan;
        else if (!std::strncmp(header.data() + 128,"DICM",4)) // DICOM
          f_type = _dcm;
        else if (uheader[0]==0xFF && uheader[1]==0xD8 && uheader[2]==0xFF) // JPEG
          f_type = _jpg;
        else if (header[0]=='B' && header[1]=='M') // BMP
          f_type = _bmp;
        else if (header[0]=='G' && header[1]=='I' && header[2]=='F' && header[3]=='8' && header[5]=='a' &&
                 (header[4]=='7' || header[4]=='9')) // GIF
          f_type = _gif;
        else if (uheader[0]==0x89 && uheader[1]==0x50 && uheader[2]==0x4E && uheader[3]==0x47 &&
                 uheader[4]==0x0D && uheader[5]==0x0A && uheader[6]==0x1A && uheader[7]==0x0A) // PNG
          f_type = _png;
        else if (uheader[0]==0x49 && uheader[1]==0x49 && uheader[2]==0x2A && uheader[3]==0x00 && // CR2
                 uheader[4]==0x10 && uheader[5]==0x00 && uheader[6]==0x00 && uheader[7]==0x00 &&
                 uheader[8]==0x43 && uheader[9]==0x52)
          f_type = _cr2;
        else if ((uheader[0]==0x49 && uheader[1]==0x49 && uheader[2]==0x2A && uheader[3]==0x00) ||
                 (uheader[0]==0x4D && uheader[1]==0x4D && uheader[2]==0x00 && uheader[3]==0x2A)) // TIFF
          f_type = _tif;
        else if (uheader[0]==0x52 && uheader[1]==0x49 && uheader[2]==0x46 && uheader[3]==0x46 &&
                 uheader[8]==0x57 && uheader[9]==0x45 && uheader[10]==0x42 && uheader[11]==0x50) // WebP
          f_type = _webp;
        else if ((uheader[0]==0xFF && uheader[1]==0x0A) ||
                 (uheader[0]==0x00 && uheader[1]==0x00 && uheader[2]==0x00 && uheader[3]==0x0C &&
                  uheader[4]==0x4A && uheader[5]==0x58 && uheader[6]==0x4C && uheader[7]==0x20 &&
                  uheader[8]==0x0D && uheader[9]==0x0A && uheader[10]==0x87 && uheader[11]==0x0A)) // JPEG XL
          f_type = _jxl;
        else if ((uheader[4]==0x66 && uheader[5]==0x74 && uheader[6]==0x79 && uheader[7]==0x70) &&
                 ((uheader[8]==0x68 && uheader[9]==0x65 && uheader[10]==0x69 && uheader[11]==0x63) ||
                  (uheader[8]==0x61 && uheader[9]==0x76 && uheader[10]==0x69 && uheader[11]==0x66))) // HEIF
          f_type = _heif;
        else { // PNM or PFM
          CImgList<char> _header = header.get_split(CImg<char>::vector('\n'),0,false);
          cimglist_for(_header,l) {
            if (_header(l,0)=='#') continue;
            if (_header[l]._width==2 && _header(l,0)=='P') {
              const char c = _header(l,1);
              if (c=='f' || c=='F') { f_type = _pfm; break; }
              if (c>='1' && c<='9') { f_type = _pnm; break; }
            }
            f_type = 0; break;
          }
        }
      } catch (CImgIOException&) { }
      cimg::exception_mode(omode);
      return f_type;
    }

    //! Load file from network as a local temporary file.
    /**
       \param url URL of the filename, as a C-string.
       \param[out] filename_local C-string containing the path to a local copy of \c filename.
       \param timeout Maximum time (in seconds) authorized for downloading the file from the URL.
       \param try_fallback When using libcurl, it asks for using system calls as fallbacks in case of libcurl failure.
       \param referer Referer used, as a C-string.
       \param user_agent User agent used, as a C-string.
       \return Value of \c filename_local.
       \note Use the \c libcurl library, or the external binaries \c wget or \c curl to perform the download.
    **/
    inline char *load_network(const char *const url, char *const filename_local,
                              const unsigned int timeout, const bool try_fallback,
                              const char *const referer, const char *const user_agent) {
      if (!url)
        throw CImgArgumentException("cimg::load_network(): Specified URL is (null).");
      if (!filename_local)
        throw CImgArgumentException("cimg::load_network(): Specified destination string is (null).");
      if (!network_mode())
        throw CImgIOException("cimg::load_network(): Loading files from network is disabled.");

      const char
        *const _user_agent = user_agent?user_agent:cimg::user_agent(),
        *const __ext = cimg::split_filename(url),
        *const _ext = (*__ext && __ext>url)?__ext - 1:__ext;
      CImg<char> ext = CImg<char>::string(_ext);
      *filename_local = 0;
      if (ext._width>16 || !cimg::strncasecmp(ext,"cgi",3)) *ext = 0;
      else cimg::strwindows_reserved(ext);
      do {
        cimg_snprintf(filename_local,256,"%s%c%s%s",
                      cimg::temporary_path(),cimg_directory_separator,cimg::filenamerand(),ext._data);
      } while (cimg::path_exists(filename_local));

#ifdef cimg_use_curl
      const unsigned int omode = cimg::exception_mode();
      cimg::exception_mode(0);
      try {
        CURL *curl = 0;
        CURLcode res;
        curl = curl_easy_init();
        if (curl) {
          std::FILE *file = cimg::fopen(filename_local,"wb");
          curl_easy_setopt(curl,CURLOPT_URL,url);
          curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,0);
          curl_easy_setopt(curl,CURLOPT_WRITEDATA,file);
          curl_easy_setopt(curl,CURLOPT_SSL_VERIFYPEER,0L);
          curl_easy_setopt(curl,CURLOPT_SSL_VERIFYHOST,0L);
          curl_easy_setopt(curl,CURLOPT_FOLLOWLOCATION,1L);
          curl_easy_setopt(curl,CURLOPT_MAXREDIRS,20L);
          curl_easy_setopt(curl,CURLOPT_USERAGENT,_user_agent);
          if (timeout) curl_easy_setopt(curl,CURLOPT_TIMEOUT,(long)timeout);
          if (std::strchr(url,'?')) curl_easy_setopt(curl,CURLOPT_HTTPGET,1L);
          if (referer) curl_easy_setopt(curl,CURLOPT_REFERER,referer);
          res = curl_easy_perform(curl);
          curl_easy_cleanup(curl);
          cimg::fseek(file,0,SEEK_END); // Check if file size is 0
          const cimg_ulong siz = cimg::ftell(file);
          cimg::fclose(file);
          file = 0;
          if (siz>0 && res==CURLE_OK) { cimg::exception_mode(omode); return filename_local; }
          else std::remove(filename_local);
        }
      } catch (...) { }
      cimg::exception_mode(omode);
      if (!try_fallback) throw CImgIOException("cimg::load_network(): Failed to load file '%s' with libcurl.",url);
#endif

      CImg<char> command((unsigned int)std::strlen(url) + 1024), s_referer, s_timeout;
      cimg::unused(try_fallback);

      // Try with 'curl' first.
      if (timeout) cimg_snprintf(s_timeout.assign(64),64,"-m %u ",timeout);
      else s_timeout.assign(1,1,1,1,0);
      if (referer) cimg_snprintf(s_referer.assign(1024),1024,"-e %s ",referer);
      else s_referer.assign(1,1,1,1,0);
      cimg_snprintf(command,command._width,
                    "\"%s\" -L --max-redirs 20 %s%s-A \"%s\" -f --silent --compressed -o \"%s\" \"%s\"",
                    cimg::curl_path(),s_timeout._data,s_referer._data,_user_agent,filename_local,
                    CImg<char>::string(url)._system_strescape().data());
      cimg::system(command,cimg::curl_path());

#if cimg_OS==2
      if (cimg::fsize(filename_local)<=0) { // Try with 'powershell' otherwise
        if (timeout) cimg_snprintf(s_timeout.assign(64),64,"-TimeoutSec %u ",timeout);
        else s_timeout.assign(1,1,1,1,0);
        if (referer) cimg_snprintf(s_referer.assign(1024),1024,"-Headers @{'Referer'='%s'} ",referer);
        else s_referer.assign(1,1,1,1,0);
        cimg_snprintf(command,command._width,
                      "\"%s\" -NonInteractive -Command Invoke-WebRequest %s%s-UserAgent \"%s\" -OutFile \"%s\" "
                      "-Uri \"%s\"",
                      cimg::powershell_path(),s_timeout._data,s_referer._data,_user_agent,filename_local,
                      CImg<char>::string(url)._system_strescape().data());
        cimg::system(command,cimg::powershell_path());
      }
#endif

      if (cimg::fsize(filename_local)<=0) { // Try with 'wget' otherwise
        if (timeout) cimg_snprintf(s_timeout.assign(64),64,"-T %u ",timeout);
        else s_timeout.assign(1,1,1,1,0);
        if (referer) cimg_snprintf(s_referer.assign(1024),1024,"--referer=%s ",referer);
        else s_referer.assign(1,1,1,1,0);
        cimg_snprintf(command,command._width,
                      "\"%s\" --max-redirect=20 %s%s--user-agent=\"%s\" -q -r -l 0 --no-cache -O \"%s\" \"%s\"",
                      cimg::wget_path(),s_timeout._data,s_referer._data,_user_agent,filename_local,
                      CImg<char>::string(url)._system_strescape().data());
        cimg::system(command,cimg::wget_path());

        if (cimg::fsize(filename_local)<=0)
          throw CImgIOException("cimg::load_network(): Failed to load file '%s' with external commands "
#if cimg_OS==2
                                "'wget', 'curl', or 'powershell'.",url);
#else
                                "'wget' or 'curl'.",url);
#endif

        // Try to gunzip it.
        cimg_snprintf(command,command._width,"%s.gz",filename_local);
        std::rename(filename_local,command);
        cimg_snprintf(command,command._width,"\"%s\" --quiet \"%s.gz\"",
                      gunzip_path(),filename_local);
        cimg::system(command,gunzip_path());
        if (!cimg::is_file(filename_local)) {
          cimg_snprintf(command,command._width,"%s.gz",filename_local);
          std::rename(command,filename_local);
        }
      }

      return filename_local;
    }

    // Implement a tic/toc mechanism to display elapsed time of algorithms.
    inline cimg_uint64 tictoc(const bool is_tic) {
      cimg::mutex(2);
      static CImg<cimg_uint64> times(64);
      static unsigned int pos = 0;
      const cimg_uint64 t1 = cimg::time();
      if (is_tic) {
        // Tic.
        times[pos++] = t1;
        if (pos>=times._width)
          throw CImgArgumentException("cimg::tic(): Too many calls to 'cimg::tic()' without calls to 'cimg::toc()'.");
        cimg::mutex(2,0);
        return t1;
      }

      // Toc.
      if (!pos)
        throw CImgArgumentException("cimg::toc(): No previous call to 'cimg::tic()' has been made.");
      const cimg_uint64
        t0 = times[--pos],
        dt = t1>=t0?(t1 - t0):cimg::type<cimg_uint64>::max();
      const unsigned int
        edays = (unsigned int)(dt/86400000.),
        ehours = (unsigned int)((dt - edays*86400000.)/3600000.),
        emin = (unsigned int)((dt - edays*86400000. - ehours*3600000.)/60000.),
        esec = (unsigned int)((dt - edays*86400000. - ehours*3600000. - emin*60000.)/1000.),
        ems = (unsigned int)(dt - edays*86400000. - ehours*3600000. - emin*60000. - esec*1000.);
      if (!edays && !ehours && !emin && !esec)
        std::fprintf(cimg::output(),"%s[CImg]%*sElapsed time: %u ms%s\n",
                     cimg::t_red(),1 + 2*pos,"",ems,cimg::t_normal());
      else {
        if (!edays && !ehours && !emin)
          std::fprintf(cimg::output(),"%s[CImg]%*sElapsed time: %u sec %u ms%s\n",
                       cimg::t_red(),1 + 2*pos,"",esec,ems,cimg::t_normal());
        else {
          if (!edays && !ehours)
            std::fprintf(cimg::output(),"%s[CImg]%*sElapsed time: %u min %u sec %u ms%s\n",
                         cimg::t_red(),1 + 2*pos,"",emin,esec,ems,cimg::t_normal());
          else{
            if (!edays)
              std::fprintf(cimg::output(),"%s[CImg]%*sElapsed time: %u hours %u min %u sec %u ms%s\n",
                           cimg::t_red(),1 + 2*pos,"",ehours,emin,esec,ems,cimg::t_normal());
            else{
              std::fprintf(cimg::output(),"%s[CImg]%*sElapsed time: %u days %u hours %u min %u sec %u ms%s\n",
                           cimg::t_red(),1 + 2*pos,"",edays,ehours,emin,esec,ems,cimg::t_normal());
            }
          }
        }
      }
      cimg::mutex(2,0);
      return dt;
    }

    // Return a temporary string describing the size of a memory buffer.
    inline const char *strbuffersize(const cimg_ulong size) {
      static CImg<char> res(256);
      cimg::mutex(5);
      if (size<1024LU) cimg_snprintf(res,res._width,"%lu byte%s",(unsigned long)size,size>1?"s":"");
      else if (size<1024*1024LU) { const float nsize = size/1024.f; cimg_snprintf(res,res._width,"%.1f Kio",nsize); }
      else if (size<1024*1024*1024LU) {
        const float nsize = size/(1024*1024.f); cimg_snprintf(res,res._width,"%.1f Mio",nsize);
      } else { const float nsize = size/(1024*1024*1024.f); cimg_snprintf(res,res._width,"%.1f Gio",nsize); }
      cimg::mutex(5,0);
      return res;
    }

    //! Display a simple dialog box, and wait for the user's response.
    /**
       \param title Title of the dialog window.
       \param msg Main message displayed inside the dialog window.
       \param button1_label Label of the 1st button.
       \param button2_label Label of the 2nd button (\c 0 to hide button).
       \param button3_label Label of the 3rd button (\c 0 to hide button).
       \param button4_label Label of the 4th button (\c 0 to hide button).
       \param button5_label Label of the 5th button (\c 0 to hide button).
       \param button6_label Label of the 6th button (\c 0 to hide button).
       \param logo Image logo displayed at the left of the main message.
       \param is_centered Indicates whether the dialog window must be centered on the screen.
       \return Index of clicked button (from \c 0 to \c 5), or \c -1 if the dialog window has been closed by the user.
       \note
       - Up to 6 buttons can be defined in the dialog window.
       - The function returns when a user clicked one of the button or closed the dialog window.
       - If a button text is set to 0, the corresponding button (and the following) will not appear in the dialog box.
       At least one button must be specified.
    **/
    template<typename t>
    inline int dialog(const char *const title, const char *const msg,
                      const char *const button1_label, const char *const button2_label,
                      const char *const button3_label, const char *const button4_label,
                      const char *const button5_label, const char *const button6_label,
                      const CImg<t>& logo, const bool is_centered=false) {
#if cimg_display==0
      cimg::unused(title,msg,logo._data,is_centered);
      cimg::unused(button1_label,button2_label,button3_label,button4_label,button5_label,button6_label);
      throw CImgIOException("cimg::dialog(): No display available.");
#else
      static const unsigned char
        black[] = { 0,0,0 }, white[] = { 255,255,255 }, gray[] = { 200,200,200 }, gray2[] = { 150,150,150 };

      // Create buttons and canvas graphics.
      CImgList<unsigned char> buttons, cbuttons, sbuttons;
      if (button1_label) {
        CImg<unsigned char>().draw_text(0,0,button1_label,black,gray,1,13).move_to(buttons);
        if (button2_label) {
          CImg<unsigned char>().draw_text(0,0,button2_label,black,gray,1,13).move_to(buttons);
          if (button3_label) {
            CImg<unsigned char>().draw_text(0,0,button3_label,black,gray,1,13).move_to(buttons);
            if (button4_label) {
              CImg<unsigned char>().draw_text(0,0,button4_label,black,gray,1,13).move_to(buttons);
              if (button5_label) {
                CImg<unsigned char>().draw_text(0,0,button5_label,black,gray,1,13).move_to(buttons);
                if (button6_label) {
                  CImg<unsigned char>().draw_text(0,0,button6_label,black,gray,1,13).move_to(buttons);
                }}}}}}
      if (!buttons._width)
        throw CImgArgumentException("cimg::dialog(): No buttons have been defined.");
      cimglist_for(buttons,l) buttons[l].resize(-100,-100,1,3);

      unsigned int bw = 0, bh = 0;
      cimglist_for(buttons,l) { bw = std::max(bw,buttons[l]._width); bh = std::max(bh,buttons[l]._height); }
      bw+=8; bh+=8;
      if (bw<64) bw = 64;
      if (bw>128) bw = 128;
      if (bh<24) bh = 24;
      if (bh>48) bh = 48;

      CImg<unsigned char> button(bw,bh,1,3);
      button.draw_rectangle(0,0,bw - 1,bh - 1,gray);
      button.draw_line(0,0,bw - 1,0,white).draw_line(0,bh - 1,0,0,white);
      button.draw_line(bw - 1,0,bw - 1,bh - 1,black).draw_line(bw - 1,bh - 1,0,bh - 1,black);
      button.draw_line(1,bh - 2,bw - 2,bh - 2,gray2).draw_line(bw - 2,bh - 2,bw - 2,1,gray2);
      CImg<unsigned char> sbutton(bw,bh,1,3);
      sbutton.draw_rectangle(0,0,bw - 1,bh - 1,gray);
      sbutton.draw_line(0,0,bw - 1,0,black).draw_line(bw - 1,0,bw - 1,bh - 1,black);
      sbutton.draw_line(bw - 1,bh - 1,0,bh - 1,black).draw_line(0,bh - 1,0,0,black);
      sbutton.draw_line(1,1,bw - 2,1,white).draw_line(1,bh - 2,1,1,white);
      sbutton.draw_line(bw - 2,1,bw - 2,bh - 2,black).draw_line(bw - 2,bh - 2,1,bh - 2,black);
      sbutton.draw_line(2,bh - 3,bw - 3,bh - 3,gray2).draw_line(bw - 3,bh - 3,bw - 3,2,gray2);
      sbutton.draw_line(4,4,bw - 5,4,black,1,0xAAAAAAAA,true).
        draw_line(bw - 5,4,bw - 5,bh - 5,black,1,0xAAAAAAAA,false);
      sbutton.draw_line(bw - 5,bh - 5,4,bh - 5,black,1,0xAAAAAAAA,false).
        draw_line(4,bh - 5,4,4,black,1,0xAAAAAAAA,false);
      CImg<unsigned char> cbutton(bw,bh,1,3);
      cbutton.draw_rectangle(0,0,bw - 1,bh - 1,black).draw_rectangle(1,1,bw - 2,bh - 2,gray2).
        draw_rectangle(2,2,bw - 3,bh - 3,gray);
      cbutton.draw_line(4,4,bw - 5,4,black,1,0xAAAAAAAA,true).
        draw_line(bw - 5,4,bw - 5,bh - 5,black,1,0xAAAAAAAA,false);
      cbutton.draw_line(bw - 5,bh - 5,4,bh - 5,black,1,0xAAAAAAAA,false).
        draw_line(4,bh - 5,4,4,black,1,0xAAAAAAAA,false);

      cimglist_for(buttons,ll) {
        CImg<unsigned char>(cbutton).
          draw_image(1 + (bw  -buttons[ll].width())/2,1 + (bh - buttons[ll].height())/2,buttons[ll]).
          move_to(cbuttons);
        CImg<unsigned char>(sbutton).
          draw_image((bw - buttons[ll].width())/2,(bh - buttons[ll].height())/2,buttons[ll]).
          move_to(sbuttons);
        CImg<unsigned char>(button).
          draw_image((bw - buttons[ll].width())/2,(bh - buttons[ll].height())/2,buttons[ll]).
          move_to(buttons[ll]);
      }

      CImg<unsigned char> canvas;
      if (msg)
        ((CImg<unsigned char>().draw_text(0,0,"%s",gray,0,1,13,msg)*=-1)+=200).resize(-100,-100,1,3).move_to(canvas);

      const unsigned int
        bwall = (buttons._width - 1)*(12 + bw) + bw,
        w = cimg::max(196U,36 + logo._width + canvas._width,24 + bwall),
        h = cimg::max(96U,36 + canvas._height + bh,36 + logo._height + bh),
        lx = 12 + (canvas._data?0:((w - 24 - logo._width)/2)),
        ly = (h - 12 - bh - logo._height)/2,
        tx = lx + logo._width + 12,
        ty = (h - 12 - bh - canvas._height)/2,
        bx = (w - bwall)/2,
        by = h - 12 - bh;

      if (canvas._data)
        canvas = CImg<unsigned char>(w,h,1,3).
          draw_rectangle(0,0,w - 1,h - 1,gray).
          draw_line(0,0,w - 1,0,white).draw_line(0,h - 1,0,0,white).
          draw_line(w - 1,0,w - 1,h - 1,black).draw_line(w - 1,h - 1,0,h - 1,black).
          draw_image(tx,ty,canvas);
      else
        canvas = CImg<unsigned char>(w,h,1,3).
          draw_rectangle(0,0,w - 1,h - 1,gray).
          draw_line(0,0,w - 1,0,white).draw_line(0,h - 1,0,0,white).
          draw_line(w - 1,0,w - 1,h - 1,black).draw_line(w - 1,h - 1,0,h - 1,black);
      if (logo._data) canvas.draw_image(lx,ly,logo);

      unsigned int xbuttons[6] = {};
      cimglist_for(buttons,lll) {
        xbuttons[lll] = bx + (bw + 12)*lll;
        canvas.draw_image(xbuttons[lll],by,buttons[lll]);
      }

      // Open window and enter events loop.
      CImgDisplay disp(canvas,title?title:" ",0,false,is_centered?true:false);
      if (is_centered) disp.move((CImgDisplay::screen_width() - disp.width())/2,
                                 (CImgDisplay::screen_height() - disp.height())/2);
      bool stop_flag = false, refresh = false;
      int oselected = -1, oclicked = -1, selected = -1, clicked = -1;
      while (!disp.is_closed() && !stop_flag) {
        if (refresh) {
          if (clicked>=0)
            CImg<unsigned char>(canvas).draw_image(xbuttons[clicked],by,cbuttons[clicked]).display(disp);
          else {
            if (selected>=0)
              CImg<unsigned char>(canvas).draw_image(xbuttons[selected],by,sbuttons[selected]).display(disp);
            else canvas.display(disp);
          }
          refresh = false;
        }
        disp.wait(15);
        if (disp.is_resized()) disp.resize(disp,false);

        if (disp.button()&1)  {
          oclicked = clicked;
          clicked = -1;
          cimglist_for(buttons,l)
            if (disp.mouse_y()>=(int)by && disp.mouse_y()<(int)(by + bh) &&
                disp.mouse_x()>=(int)xbuttons[l] && disp.mouse_x()<(int)(xbuttons[l] + bw)) {
              clicked = selected = l;
              refresh = true;
            }
          if (clicked!=oclicked) refresh = true;
        } else if (clicked>=0) stop_flag = true;

        if (disp.key()) {
          oselected = selected;
          switch (disp.key()) {
          case cimg::keyESC : selected = -1; stop_flag = true; break;
          case cimg::keyRETURN : if (selected<0) selected = 0; stop_flag = true; break;
          case cimg::keyTAB :
          case cimg::keyARROWRIGHT :
          case cimg::keyARROWDOWN : selected = (selected + 1)%buttons.width(); break;
          case cimg::keyARROWLEFT :
          case cimg::keyARROWUP : selected = (selected + buttons.width() - 1)%buttons.width(); break;
          }
          disp.set_key();
          if (selected!=oselected) refresh = true;
        }
      }
      if (!disp) selected = -1;
      return selected;
#endif
    }

    //! Display a simple dialog box, and wait for the user's response \specialization.
    inline int dialog(const char *const title, const char *const msg,
                      const char *const button1_label, const char *const button2_label,
                      const char *const button3_label, const char *const button4_label,
                      const char *const button5_label, const char *const button6_label,
                      const bool is_centered) {
      return dialog(title,msg,button1_label,button2_label,button3_label,button4_label,button5_label,button6_label,
                    CImg<unsigned char>::logo40x38(),is_centered);
    }

    //! Evaluate math expression.
    /**
       \param expression C-string describing the formula to evaluate.
       \param x Value of the predefined variable \c x.
       \param y Value of the predefined variable \c y.
       \param z Value of the predefined variable \c z.
       \param c Value of the predefined variable \c c.
       \return Result of the formula evaluation.
       \note Set \c expression to \c 0 to keep evaluating the last specified \c expression.
       \par Example
       \code
       const double
       res1 = cimg::eval("cos(x)^2 + sin(y)^2",2,2), // will return '1'
       res2 = cimg::eval(0,1,1); // will return '1' too
       \endcode
    **/
    inline double eval(const char *const expression, const double x, const double y, const double z, const double c) {
      static const CImg<float> empty;
      return empty.eval(expression,x,y,z,c);
    }

    template<typename t>
    inline CImg<typename cimg::superset<double,t>::type> eval(const char *const expression, const CImg<t>& xyzc) {
      static const CImg<float> empty;
      return empty.eval(expression,xyzc);
    }

    // Define a 10x13 binary font (small sans).
    inline const char* data_font_small() {
      return
      "                      UwlwnwoyuwHwlwmwcwlwnw[xuwowlwmwoyuwRwlwnxcw     Mw                    (wnwnwuwpwuypwuwoy"
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      "wuwoyZwmwnwuwowuwmwqwkwuwowuwoxnwuxowmwnwuwpwuypwuwZwmwnwuwowuwnwowmwtw\\wuwuwqwswqwswqwswqwswEwqwtweypzr~qyIw "
      "rwswewnwuwowuwozswtwuwqwtwmwnwlwowuwuwowOxpxuxqwuwowswqwswoxpwlwjwqwswqwsw<wrwowrwuwqwrwqwswrwswpwmwmwrwswrwowl"
      "wqwtwownxsxsxswqwswqwswqwswrwswqwrwowpwrwrwqwtwswswswswqwswmwpwmwlwoxuxSw_wfwdwYwkw(w0wmwmwGwtwoxnwNw uwswpwuwp"
      "wmwmwswq{rwrwrwtwtwrwswfydwdyZwnwtwrwqwrwswowowdwrwqxuwSwrwfwuwnwlwnw[yuw[wowtwgwswqwswqwswewuwowuwowuwowuwowuw"
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      "wqwswqwswqwswqwswqwswgwtxqwswqwswqwswqwswrwrwqwswrwrw^wtwtwswqwswuwuwuwswuwswswqwHwowuwf}t~s|r}swrwrwrwqwtwpwtw"
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      "xWw=wKwowewawcwow  Yw  hwVx 8w   9w  Jxmwnxp"; }

    // Define a 26x32 font (normal sans).
    inline const char* data_font_normal() {
      return
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      "l{}`~}                Ww~|                                                                                     "
      "                                            L{}`~}                Ww}|                                         "
      "                                  r{";

      static CImg<char> value;
      if (!value) {
        cimg::mutex(0);
        const size_t s0 = std::strlen(chunk0), s1 = std::strlen(chunk1);
        if (!value) {
          value.assign(s0 + s1 + 1);
          std::memcpy(value._data,chunk0,s0);
          std::memcpy(value._data + s0,chunk1,s1 + 1);
        }
        cimg::mutex(0,0);
      }
      return value;
    }

    // Define a 104x128 binary font (huge sans).
    inline const char* data_font_huge() {
      const char *const chunk0 =
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      "  ,X /X 0Y          +Y         8Y 4Y   *Y    1Y    EX 3Y                                          CZ          '"
      "X                                5Y      -c               Nm                 Fc                                "
      "                                      =c                                               $c +Y  Nc               "
      "  >a                                                                                                           "
      "                   M\\                     8a                                             \"~Y                1"
      "r     !`            +Y  'X                0c      1X            1Y         8Y 4Y   *Y    1Y    EX 3Y           "
      "                               CZ          &W                                5Y      -b               Lj       "
      "          Db                                                                      <b                           "
      "                    #b *Y  Nb                 <_                                                               "
      "                                                                                    (_                         "
      "                     ~Y                1q      _            *Y  'X                0b      0X            1Y     "
      "    8Y 4Y   *Y    1Y    EX 3Y                                          CZ                                      "
      "     3Y      -`               He                 A`                                                            "
      "          :`                                               !a )Y  Na                 :]                        "
      "                                                                                                               "
      "            ']                                              M~Y                .l      M]            (Y  'X    "
      "            0`      .X            1Y         8Y 4Y   *Y    1Y    EX 3Y                                         "
      "                                             KY      *Z               B^                 9Z                    "
      "                                                  5Z                                                M` (Y  N`  "
      "               8Z                                                                                              "
      "                                                     %X                                              H~Y       "
      "         *d      I[            &Y  'X                0^      ,X            1Y         8Y 4Y   *Y    1Y    EX 3Y"
      "                                                                                      KY                       "
      "                                                                                                               "
      "                         H^ &Y  N]                 3V                                                          "
      "                                                                                                               "
      "                         B~Y                #X      CU            !X  &X                /Y      (X            1"
      "Y         7X 4X   )X    0Y    EX 2X                                                                            "
      "          KY                                                                                                   "
      "                                                            HZ \"X  MY                                         "
      "                                                                                                               "
      "                                                            J~Y                                                "
      "               9X                                                                                              "
      "                                                                                                               "
      "                                                                                                               "
      "                                                                                                               "
      "                                                                          3~Y                                  "
      "                             9X                                                                                "
      "                                                                                                               "
      "                                                                                                               "
      "                                                                                                               "
      "                                                                                        3~Y                    "
      "                                           9X                                                                  "
      "                                                                                                               "
      "                                                                                                               "
      "  '";

      static CImg<char> value;
      if (!value) {
        cimg::mutex(0);
        const size_t s0 = std::strlen(chunk0), s1 = std::strlen(chunk1);
        if (!value) {
          value.assign(s0 + s1 + 1);
          std::memcpy(value._data,chunk0,s0);
          std::memcpy(value._data + s0,chunk1,s1 + 1);
        }
        cimg::mutex(0,0);
      }
      return value;
    }

  } // namespace cimg { ...
} // namespace cimg_library { ...

//! Short alias name.
namespace cil = cimg_library;

#ifdef _cimg_redefine_False
#define False 0
#endif
#ifdef _cimg_redefine_True
#define True 1
#endif
#ifdef _cimg_redefine_Status
#define Status int
#endif
#ifdef _cimg_redefine_Success
#define Success 0
#endif
#ifdef _cimg_redefine_min
#define min(a,b) (((a)<(b))?(a):(b))
#endif
#ifdef _cimg_redefine_max
#define max(a,b) (((a)>(b))?(a):(b))
#endif
#ifdef _cimg_redefine_PI
#define PI 3.141592653589793238462643383
#endif
#ifdef _MSC_VER
#pragma warning(pop)
#endif
#if __GNUC__>10
#pragma GCC diagnostic pop
#endif

#endif

// Local Variables:
// mode: c++
// End:
