bool writeImagePGM (const char* const outfile, int nxcell, int nycell, double densmin, double densmax);
bool writeImagePGMASCII (const char* const outfile, int nxcell, int nycell, double densmin, double densmax);
bool readImagePPM (const char* const pszFile);
bool writeImagePGM (const char* const outfile, int nxcell, int nycell, double densmin, double densmax);
bool writeImagePGMASCII (const char* const outfile, int nxcell, int nycell, double densmin, double densmax);
bool readImagePPM (const char* const pszFile);