PNG_COLOR_DIST    507 3rdparty/libpng/pngrtran.c                   min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
PNG_COLOR_DIST    512 3rdparty/libpng/pngrtran.c                      d = PNG_COLOR_DIST(palette[d_index], palette[k]);
PNG_COLOR_DIST    584 3rdparty/libpng/pngrtran.c                   d = PNG_COLOR_DIST(palette[i], palette[j]);