CImg.h

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      cimglist_for(*this,l) {
        CImg<ucharT> YCbCr((*this)[l]);
        if (is_rgb) YCbCr.RGBtoYCbCr();
        cimg::fwrite(YCbCr._data,(size_t)YCbCr._width*YCbCr._height,nfile);
        cimg::fwrite(YCbCr.get_resize(YCbCr._width/2, YCbCr._height/2,1,3,3).data(0,0,0,1),
                     (size_t)YCbCr._width*YCbCr._height/2,nfile);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save list as a YUV image sequence file.
    /**
      \param filename Filename to write data to.
      \param is_rgb Tells if the RGB to YUV conversion must be done for saving.
    **/
    const CImgList<T>& save_yuv(const char *const filename=0, const bool is_rgb=true) const {
      return _save_yuv(0,filename,is_rgb);
    }

    //! Save image sequence into a YUV file.
    /**
      \param file File to write data to.
      \param is_rgb Tells if the RGB to YUV conversion must be done for saving.
    **/
    const CImgList<T>& save_yuv(std::FILE *const file, const bool is_rgb=true) const {
      return _save_yuv(file,0,is_rgb);
    }

    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
      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const char *const ptype = pixel_type(), *const etype = cimg::endianness()?"big":"little";
      if (std::strstr(ptype,"unsigned")==ptype) std::fprintf(nfile,"%u unsigned_%s %s_endian\n",_width,ptype + 9,etype);
      else 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
            const ulongT siz = sizeof(T)*ref.size();
            uLongf csiz = siz + siz/100 + 16;
            Bytef *const cbuf = new Bytef[csiz];
            if (compress(cbuf,&csiz,(Bytef*)ref._data,siz))
              cimg::warn(_cimglist_instance
                         "save_cimg(): Failed to save compressed data for file '%s', saving them uncompressed.",
                         cimglist_instance,
                         filename?filename:"(FILE*)");
            else {
              std::fprintf(nfile," #%lu\n",csiz);
              cimg::fwrite(cbuf,csiz,nfile);
              delete[] cbuf;
              failed_to_compress = false;
            }
#endif
          }
          if (failed_to_compress) { // Write in a non-compressed way.
            std::fputc('\n',nfile);
            cimg::fwrite(ref._data,ref.size(),nfile);
          }
        } else std::fputc('\n',nfile);
      }
      if (!file) cimg::fclose(nfile);
      return *this;
    }

    //! Save list into a .cimg file.
    /**
       \param filename Filename to write data to.
       \param is_compressed Tells if 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);
    }

    //! Save list into a .cimg file.
    /**
       \param file File to write data to.
       \param is_compressed Tells if 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(Ts,Tss) \
      if (!saved && !cimg::strcasecmp(Ts,str_pixeltype)) { \
        for (unsigned int l = 0; l<lmax; ++l) { \
          j = 0; while ((i=std::fgetc(nfile))!='\n') tmp[j++]=(char)i; tmp[j] = 0; \
          W = H = D = C = 0; \
          if (cimg_sscanf(tmp,"%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,"%u%*c%255[A-Za-z64_]%*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",bool);
      _cimg_save_cimg_case("unsigned_char",unsigned char);
      _cimg_save_cimg_case("uchar",unsigned char);
      _cimg_save_cimg_case("char",char);
      _cimg_save_cimg_case("unsigned_short",unsigned short);
      _cimg_save_cimg_case("ushort",unsigned short);
      _cimg_save_cimg_case("short",short);
      _cimg_save_cimg_case("unsigned_int",unsigned int);
      _cimg_save_cimg_case("uint",unsigned int);
      _cimg_save_cimg_case("int",int);
      _cimg_save_cimg_case("unsigned_int64",uint64T);
      _cimg_save_cimg_case("uint64",uint64T);
      _cimg_save_cimg_case("int64",int64T);
      _cimg_save_cimg_case("float",float);
      _cimg_save_cimg_case("double",double);
      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 instance into 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 instance into 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 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 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 list as a TIFF file.
    /**
      \param filename Filename to write data to.
      \param compression_type Compression mode used to write data.
    **/
    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) {
        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);
        }
        TIFFClose(tif);
      } else
        throw CImgIOException(_cimglist_instance
                              "save_tiff(): Failed to open stream for file '%s'.",
                              cimglist_instance,
                              filename);
#endif
      return *this;
    }

    //! Save list as a gzipped file, using 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);
      std::FILE *file;
      do {
        if (!cimg::strcasecmp(ext,"gz")) {
          if (*ext2) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                   cimg::temporary_path(),cimg_file_separator,cimg::filenamerand(),ext2);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_file_separator,cimg::filenamerand());
        } else {
          if (*ext) cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.%s",
                                  cimg::temporary_path(),cimg_file_separator,cimg::filenamerand(),ext);
          else cimg_snprintf(filename_tmp,filename_tmp._width,"%s%c%s.cimg",
                             cimg::temporary_path(),cimg_file_separator,cimg::filenamerand());
        }
        if ((file=std_fopen(filename_tmp,"rb"))!=0) cimg::fclose(file);
      } while (file);

      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());
        cimg::system(command);
        file = std_fopen(filename,"rb");
        if (!file)
          throw CImgIOException(_cimglist_instance
                                "save_gzip_external(): Failed to save file '%s' with external command 'gzip'.",
                                cimglist_instance,
                                filename);
        else cimg::fclose(file);
        std::remove(filename_tmp);
      } else {
        CImg<charT> nfilename(1024);
        cimglist_for(*this,l) {
          cimg::number_filename(body,l,6,nfilename);
          if (*ext) cimg_sprintf(nfilename._data + std::strlen(nfilename),".%s",ext);
          _data[l].save_gzip_external(nfilename);
        }
      }
      return *this;
    }

    //! Save image sequence, using the OpenCV library.
    /**
       \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 Tells if the video writer associated to the specified filename
       must be kept open or not (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);
      return save_ffmpeg_external(filename,fps);
#else
      static CvVideoWriter *writers[32] = { 0 };
      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);

#define _cimg_docase(x) ((x)>='a'&&(x)<='z'?(x) + 'A' - 'a':(x))
        const char
          *const _codec = codec && *codec?codec:"mp4v",
          codec0 = _cimg_docase(_codec[0]),
          codec1 = _codec[0]?_cimg_docase(_codec[1]):0,
          codec2 = _codec[1]?_cimg_docase(_codec[2]):0,
          codec3 = _codec[2]?_cimg_docase(_codec[3]):0;
        cimg::mutex(9);
        writers[index] = cvCreateVideoWriter(filename,CV_FOURCC(codec0,codec1,codec2,codec3),
                                             fps,cvSize(W,H));
        CImg<charT>::string(filename).move_to(filenames[index]);
        sizes(index,0) = W; sizes(index,1) = H;
        cimg::mutex(9,0);
        if (!writers[index])
          throw CImgIOException(_cimglist_instance
                                "save_video(): File '%s', unable to initialize video writer with codec '%c%c%c%c'.",
                                cimglist_instance,filename,
                                codec0,codec1,codec2,codec3);
      }

      if (!is_empty()) {
        const unsigned int W = sizes(index,0), H = sizes(index,1);
        cimg::mutex(9);
        IplImage *ipl = cvCreateImage(cvSize(W,H),8,3);
        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._depth>1 || 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);
          if (src._width==W && src._height==H && src._spectrum==3) {
            const T *ptr_r = src.data(0,0,0,0), *ptr_g = src.data(0,0,0,1), *ptr_b = src.data(0,0,0,2);
            char *ptrd = ipl->imageData;
            cimg_forXY(src,x,y) {
              *(ptrd++) = (char)*(ptr_b++); *(ptrd++) = (char)*(ptr_g++); *(ptrd++) = (char)*(ptr_r++);
            }
          } else {
            CImg<unsigned char> _src(src,false);
            _src.channels(0,std::min(_src._spectrum - 1,2U)).resize(W,H);
            _src.resize(W,H,1,3,_src._spectrum==1);
            const unsigned char *ptr_r = _src.data(0,0,0,0), *ptr_g = _src.data(0,0,0,1), *ptr_b = _src.data(0,0,0,2);
            char *ptrd = ipl->imageData;
            cimg_forXY(_src,x,y) {
              *(ptrd++) = (char)*(ptr_b++); *(ptrd++) = (char)*(ptr_g++); *(ptrd++) = (char)*(ptr_r++);
            }
          }
          cvWriteFrame(writers[index],ipl);
        }
        cvReleaseImage(&ipl);
        cimg::mutex(9,0);
      }

      cimg::mutex(9);
      if (!keep_open) {
        cvReleaseVideoWriter(&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);

      return *this;
#endif
    }

    //! Save 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":"mpeg2video";

      CImg<charT> command(1024), filename_tmp(256), filename_tmp2(256);
      CImgList<charT> filenames;
      std::FILE *file = 0;
      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_file_separator,cimg::filenamerand());
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_000001.ppm",filename_tmp._data);
        if ((file=std_fopen(filename_tmp2,"rb"))!=0) cimg::fclose(file);
      } while (file);
      cimglist_for(*this,l) {
        cimg_snprintf(filename_tmp2,filename_tmp2._width,"%s_%.6u.ppm",filename_tmp._data,l + 1);
        CImg<charT>::string(filename_tmp2).move_to(filenames);
        if (_data[l]._depth>1 || _data[l]._spectrum!=3) _data[l].get_resize(-100,-100,1,3).save_pnm(filename_tmp2);
        else _data[l].save_pnm(filename_tmp2);
      }
#if cimg_OS!=2
      cimg_snprintf(command,command._width,"%s -i \"%s_%%6d.ppm\" -vcodec %s -b %uk -r %u -y \"%s\" >/dev/null 2>&1",
                    cimg::ffmpeg_path(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    _codec,bitrate,fps,
                    CImg<charT>::string(filename)._system_strescape().data());
#else
      cimg_snprintf(command,command._width,"\"%s -i \"%s_%%6d.ppm\" -vcodec %s -b %uk -r %u -y \"%s\"\" >NUL 2>&1",
                    cimg::ffmpeg_path(),
                    CImg<charT>::string(filename_tmp)._system_strescape().data(),
                    _codec,bitrate,fps,
                    CImg<charT>::string(filename)._system_strescape().data());
#endif
      cimg::system(command);
      file = std_fopen(filename,"rb");
      if (!file)
        throw CImgIOException(_cimglist_instance
                              "save_ffmpeg_external(): Failed to save file '%s' with external command 'ffmpeg'.",
                              cimglist_instance,
                              filename);
      else cimg::fclose(file);
      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 tells if zlib compression must be used for serialization
       (this requires 'cimg_use_zlib' been enabled).
    **/
    CImg<ucharT> get_serialize(const bool is_compressed=false) 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;
      CImg<charT> tmpstr(128);
      const char *const ptype = pixel_type(), *const etype = cimg::endianness()?"big":"little";
      if (std::strstr(ptype,"unsigned")==ptype)
        cimg_snprintf(tmpstr,tmpstr._width,"%u unsigned_%s %s_endian\n",_width,ptype + 9,etype);
      else
        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.size()*sizeof(T),1,1,1,true);
          }
        } else CImg<charT>::string("\n",false).move_to(stream);
      }
      cimglist_apply(stream,unroll)('y');
      return stream>'y';
    }

    //! Unserialize a CImg<unsigned char> serialized buffer into a CImgList<T> list.
    template<typename t>
    static CImgList<T> get_unserialize(const CImg<t>& buffer) {
#ifdef cimg_use_zlib
#define _cimgz_unserialize_case(Tss) { \
        Bytef *cbuf = (Bytef*)stream; \
        if (sizeof(t)!=1 || cimg::type<t>::string()==cimg::type<bool>::string()) { \
          cbuf = new Bytef[csiz]; Bytef *_cbuf = cbuf; \
          for (ulongT i = 0; i<csiz; ++i) *(_cbuf++) = (Bytef)*(stream++); \
          is_bytef = false; \
        } else { stream+=csiz; is_bytef = true; } \
        CImg<Tss> raw(W,H,D,C); \
        uLongf destlen = raw.size()*sizeof(Tss); \
        uncompress((Bytef*)raw._data,&destlen,cbuf,csiz); \
        if (!is_bytef) delete[] cbuf; \
        if (endian!=cimg::endianness()) cimg::invert_endianness(raw._data,raw.size()); \
        raw.move_to(img); \
      }
#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(Ts,Tss) \
      if (!loaded && !cimg::strcasecmp(Ts,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,"%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<T> &img = res._data[l]; \
            if (err==5) _cimgz_unserialize_case(Tss) \
            else { \
              if (sizeof(t)!=1) { \
                CImg<ucharT> raw(W*sizeof(Tss),H,D,C);  \
                cimg_for(raw,p,unsigned char) *p = (unsigned char)*(stream++); \
                img.assign((Tss*)raw._data,W,H,D,C); \
              } else img.assign((Tss*)stream,W,H,D,C); \
              if (endian!=cimg::endianness()) cimg::invert_endianness(img._data,img.size()); \
            } \
          } \
        } \
        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, *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,"%u%*c%255[A-Za-z64_]%*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",bool);
      _cimg_unserialize_case("unsigned_char",unsigned char);
      _cimg_unserialize_case("uchar",unsigned char);
      _cimg_unserialize_case("char",char);
      _cimg_unserialize_case("unsigned_short",unsigned short);
      _cimg_unserialize_case("ushort",unsigned short);
      _cimg_unserialize_case("short",short);
      _cimg_unserialize_case("unsigned_int",unsigned int);
      _cimg_unserialize_case("uint",unsigned int);
      _cimg_unserialize_case("int",int);
      _cimg_unserialize_case("unsigned_int64",uint64T);
      _cimg_unserialize_case("uint64",uint64T);
      _cimg_unserialize_case("int64",int64T);
      _cimg_unserialize_case("float",float);
      _cimg_unserialize_case("double",double);
      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
    //@{
    //----------------------------------

    //! Crop font along the X-axis.
    /**
    **/
    CImgList<T>& crop_font() {
      return get_crop_font().move_to(*this);
    }

    //! Crop font along the X-axis \newinstance.
    /**
    **/
    CImgList<T> get_crop_font() const {
      CImgList<T> res;
      cimglist_for(*this,l) {
        const CImg<T>& letter = (*this)[l];
        int xmin = letter.width(), xmax = 0;
        cimg_forXY(letter,x,y) if (letter(x,y)) { if (x<xmin) xmin = x; if (x>xmax) xmax = x; }
        if (xmin>xmax) CImg<T>(letter._width,letter._height,1,letter._spectrum,0).move_to(res);
        else letter.get_crop(xmin,0,xmax,letter._height - 1).move_to(res);
      }
      res[' '].resize(res['f']._width,-100,-100,-100,0);
      if (' ' + 256<res.size()) res[' ' + 256].resize(res['f']._width,-100,-100,-100,0);
      return res;
    }

    //! Return a CImg pre-defined font with desired size.
    /**
       \param font_height Height of the desired font (exact match for 13,23,53,103).
       \param is_variable_width Decide if the font has a variable (\c true) or fixed (\c false) width.
    **/
    static const CImgList<ucharT>& font(const unsigned int font_height, const bool is_variable_width=true) {
      if (!font_height) return CImgList<ucharT>::const_empty();
      cimg::mutex(11);

      // Decompress nearest base font data if needed.
      static const char *data_fonts[] = { cimg::data_font12x13, cimg::data_font20x23, cimg::data_font47x53, 0 };
      static const unsigned int data_widths[] = { 12,20,47,90 }, data_heights[] = { 13,23,53,103 },
                                data_Ms[] = { 86,79,57,47 };
      const unsigned int data_ind = font_height<=13U?0U:font_height<=23U?1U:font_height<=53U?2U:3U;
      static CImg<ucharT> base_fonts[4];
      CImg<ucharT> &base_font = base_fonts[data_ind];
      if (!base_font) {
        const unsigned int w = data_widths[data_ind], h = data_heights[data_ind], M = data_Ms[data_ind];
        base_font.assign(256*w,h);
        const char *data_font = data_fonts[data_ind];
        unsigned char *ptrd = base_font;
        const unsigned char *const ptrde = base_font.end();

        // Special case needed for 90x103 to avoid MS compiler limit with big strings.
        CImg<char> data90x103;
        if (!data_font) {
          ((CImg<char>(cimg::_data_font90x103[0],
                       (unsigned int)std::strlen(cimg::_data_font90x103[0]),1,1,1,true),
            CImg<char>(cimg::_data_font90x103[1],
                       (unsigned int)std::strlen(cimg::_data_font90x103[1]) + 1,1,1,1,true))>'x').
            move_to(data90x103);
          data_font = data90x103.data();
        }

        // Uncompress font data (decode RLE).
        for (const char *ptrs = data_font; *ptrs; ++ptrs) {
          const int c = (int)(*ptrs - M - 32), v = c>=0?255:0, n = c>=0?c:-c;
          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[16];
      static bool is_variable_widths[16] = { 0 };
      unsigned int ind = ~0U;
      for (int i = 0; i<16; ++i)
        if (!fonts[i] || (is_variable_widths[i]==is_variable_width && font_height==fonts[i][0]._height)) {
          ind = (unsigned int)i; break; // Found empty slot or cached font.
        }
      if (ind==~0U) { // No empty slots nor existing font in cache.
        fonts->assign();
        std::memmove(fonts,fonts + 1,15*sizeof(CImgList<ucharT>));
        std::memmove(is_variable_widths,is_variable_widths + 1,15*sizeof(bool));
        std::memset(fonts + (ind=15),0,sizeof(CImgList<ucharT>)); // Free a slot in cache for new font.
      }
      CImgList<ucharT> &font = fonts[ind];

      // Render requested font.
      if (!font) {
        const unsigned int padding_x = font_height<33U?1U:font_height<53U?2U:font_height<103U?3U:4U;
        is_variable_widths[ind] = is_variable_width;
        font = base_font.get_split('x',256);
        if (font_height!=font[0]._height)
          cimglist_for(font,l)
            font[l].resize(std::max(1U,font[l]._width*font_height/font[l]._height),font_height,-100,-100,
                           font[0]._height>font_height?2:5);
        if (is_variable_width) font.crop_font();
        cimglist_for(font,l) font[l].resize(font[l]._width + padding_x,-100,1,1,0,0,0.5);
        font.insert(256,0);
        cimglist_for_in(font,0,255,l) font[l].assign(font[l + 256]._width,font[l + 256]._height,1,3,1);
      }
      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 Tells if 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 a n-d Fast Fourier Transform.
    /**
      \param invert Tells if 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 a n-d Fast Fourier Transform \newinstance.
    CImgList<Tfloat> get_FFT(const bool invert=false) const {
      return CImgList<Tfloat>(*this,false).FFT(invert);
    }

    //! Reverse primitives orientations of a 3d object.
    /**
    **/
    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 primitives orientations of a 3d object \newinstance.
    CImgList<T> get_reverse_object3d() const {
      return (+*this).reverse_object3d();
    }

    //@}
  }; // struct CImgList<T> { ...

  /*
    #---------------------------------------------
    #
    # 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 (with wide character support on Windows).
  inline std::FILE *win_fopen(const char *const path, const char *const mode) {
#if cimg_OS==2
    // Convert 'path' to a wide-character string.
    int err = MultiByteToWideChar(CP_UTF8,0,path,-1,0,0);
    if (!err) return std_fopen(path,mode);
    CImg<wchar_t> wpath(err);
    err = MultiByteToWideChar(CP_UTF8,0,path,-1,wpath,err);
    if (!err) return std_fopen(path,mode);

    // Convert 'mode' to a wide-character string.
    err = MultiByteToWideChar(CP_UTF8,0,mode,-1,0,0);
    if (!err) return std_fopen(path,mode);
    CImg<wchar_t> wmode(err);
    err = MultiByteToWideChar(CP_UTF8,0,mode,-1,wmode,err);
    if (!err) return std_fopen(path,mode);

    return _wfopen(wpath,wmode);
#else
    return std_fopen(path,mode);
#endif
  }

  //! 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_file_separator,filename_tmp._data); \
      if ((file=std_fopen(tmp,"wb"))!=0) { cimg::fclose(file); std::remove(tmp); path_found = true; } \