WEBP_FILTER_GRADIENT  280 3rdparty/libwebp/enc/alpha.c            ok && (test_filter <= WEBP_FILTER_GRADIENT);
WEBP_FILTER_GRADIENT  184 3rdparty/libwebp/utils/filters.c       bins[WEBP_FILTER_GRADIENT][diff3] = 1;
WEBP_FILTER_GRADIENT   29 3rdparty/libwebp/utils/filters.h   WEBP_FILTER_LAST = WEBP_FILTER_GRADIENT + 1,  // end marker