diff --git a/src/enc/vp8l.c b/src/enc/vp8l.c index 58cbccb1..4d419cb5 100644 --- a/src/enc/vp8l.c +++ b/src/enc/vp8l.c @@ -1167,7 +1167,8 @@ static WebPEncodingError MakeInputImageCopy(VP8LEncoder* const enc) { // ----------------------------------------------------------------------------- -static int SearchColor(const uint32_t sorted[], uint32_t color, int hi) { +static WEBP_INLINE int SearchColorNoIdx(const uint32_t sorted[], uint32_t color, + int hi) { int low = 0; if (sorted[low] == color) return low; // loop invariant: sorted[low] != color while (1) { @@ -1182,35 +1183,68 @@ static int SearchColor(const uint32_t sorted[], uint32_t color, int hi) { } } +#define APPLY_PALETTE_GREEDY_MAX 4 + +static WEBP_INLINE uint32_t SearchColorGreedy(const uint32_t palette[], + int palette_size, + uint32_t color) { + (void)palette_size; + assert(palette_size < APPLY_PALETTE_GREEDY_MAX); + assert(3 == APPLY_PALETTE_GREEDY_MAX - 1); + if (color == palette[0]) return 0; + if (color == palette[1]) return 1; + if (color == palette[2]) return 2; + return 3; +} + +static WEBP_INLINE uint32_t ApplyPaletteHash0(uint32_t color) { + // Focus on the green color. + return (color >> 8) & 0xff; +} + +#define PALETTE_INV_SIZE_BITS 11 +#define PALETTE_INV_SIZE (1 << PALETTE_INV_SIZE_BITS) + +static WEBP_INLINE uint32_t ApplyPaletteHash1(uint32_t color) { + // Forget about alpha. + return ((color & 0x00ffffffu) * 4222244071u) >> (32 - PALETTE_INV_SIZE_BITS); +} + +static WEBP_INLINE uint32_t ApplyPaletteHash2(uint32_t color) { + // Forget about alpha. + return (color & 0x00ffffffu) * ((1u << 31) - 1) >> + (32 - PALETTE_INV_SIZE_BITS); +} + // Sort palette in increasing order and prepare an inverse mapping array. static void PrepareMapToPalette(const uint32_t palette[], int num_colors, - uint32_t sorted[], int idx_map[]) { + uint32_t sorted[], uint32_t idx_map[]) { int i; memcpy(sorted, palette, num_colors * sizeof(*sorted)); qsort(sorted, num_colors, sizeof(*sorted), PaletteCompareColorsForQsort); for (i = 0; i < num_colors; ++i) { - idx_map[SearchColor(sorted, palette[i], num_colors)] = i; + idx_map[SearchColorNoIdx(sorted, palette[i], num_colors)] = i; } } -static void MapToPalette(const uint32_t sorted_palette[], int num_colors, - uint32_t* const last_pix, int* const last_idx, - const int idx_map[], - const uint32_t* src, uint8_t* dst, int width) { - int x; - int prev_idx = *last_idx; - uint32_t prev_pix = *last_pix; - for (x = 0; x < width; ++x) { - const uint32_t pix = src[x]; - if (pix != prev_pix) { - prev_idx = idx_map[SearchColor(sorted_palette, pix, num_colors)]; - prev_pix = pix; - } - dst[x] = prev_idx; - } - *last_idx = prev_idx; - *last_pix = prev_pix; -} +// Use 1 pixel cache for ARGB pixels. +#define APPLY_PALETTE_FOR(COLOR_INDEX) do { \ + uint32_t prev_pix = palette[0]; \ + uint32_t prev_idx = 0; \ + for (y = 0; y < height; ++y) { \ + for (x = 0; x < width; ++x) { \ + const uint32_t pix = src[x]; \ + if (pix != prev_pix) { \ + prev_idx = COLOR_INDEX; \ + prev_pix = pix; \ + } \ + tmp_row[x] = prev_idx; \ + } \ + VP8LBundleColorMap(tmp_row, width, xbits, dst); \ + src += src_stride; \ + dst += dst_stride; \ + } \ +} while (0) // Remap argb values in src[] to packed palettes entries in dst[] // using 'row' as a temporary buffer of size 'width'. @@ -1223,52 +1257,59 @@ static WebPEncodingError ApplyPalette(const uint32_t* src, uint32_t src_stride, // TODO(skal): this tmp buffer is not needed if VP8LBundleColorMap() can be // made to work in-place. uint8_t* const tmp_row = (uint8_t*)WebPSafeMalloc(width, sizeof(*tmp_row)); - int i, x, y; - int use_LUT = 1; + int x, y; if (tmp_row == NULL) return VP8_ENC_ERROR_OUT_OF_MEMORY; - for (i = 0; i < palette_size; ++i) { - if ((palette[i] & 0xffff00ffu) != 0) { - use_LUT = 0; - break; - } - } - if (use_LUT) { - uint8_t inv_palette[MAX_PALETTE_SIZE] = { 0 }; - for (i = 0; i < palette_size; ++i) { - const int color = (palette[i] >> 8) & 0xff; - inv_palette[color] = i; - } - for (y = 0; y < height; ++y) { - for (x = 0; x < width; ++x) { - const int color = (src[x] >> 8) & 0xff; - tmp_row[x] = inv_palette[color]; - } - VP8LBundleColorMap(tmp_row, width, xbits, dst); - src += src_stride; - dst += dst_stride; - } + if (palette_size < APPLY_PALETTE_GREEDY_MAX) { + APPLY_PALETTE_FOR(SearchColorGreedy(palette, palette_size, pix)); } else { - // Use 1 pixel cache for ARGB pixels. - uint32_t last_pix; - int last_idx; - uint32_t sorted[MAX_PALETTE_SIZE]; - int idx_map[MAX_PALETTE_SIZE]; - PrepareMapToPalette(palette, palette_size, sorted, idx_map); - last_pix = palette[0]; - last_idx = 0; - for (y = 0; y < height; ++y) { - MapToPalette(sorted, palette_size, &last_pix, &last_idx, - idx_map, src, tmp_row, width); - VP8LBundleColorMap(tmp_row, width, xbits, dst); - src += src_stride; - dst += dst_stride; + int i, j; + uint16_t buffer[PALETTE_INV_SIZE]; + uint32_t (*const hash_functions[])(uint32_t) = { + ApplyPaletteHash0, ApplyPaletteHash1, ApplyPaletteHash2 + }; + + // Try to find a perfect hash function able to go from a color to an index + // within 1 << PALETTE_INV_SIZE_BITS in order to build a hash map to go + // from color to index in palette. + for (i = 0; i < 3; ++i) { + int use_LUT = 1; + // Set each element in buffer to max uint16_t. + memset(buffer, 0xff, sizeof(buffer)); + for (j = 0; j < palette_size; ++j) { + const uint32_t ind = hash_functions[i](palette[j]); + if (buffer[ind] != 0xffffu) { + use_LUT = 0; + break; + } else { + buffer[ind] = j; + } + } + if (use_LUT) break; + } + + if (i == 0) { + APPLY_PALETTE_FOR(buffer[ApplyPaletteHash0(pix)]); + } else if (i == 1) { + APPLY_PALETTE_FOR(buffer[ApplyPaletteHash1(pix)]); + } else if (i == 2) { + APPLY_PALETTE_FOR(buffer[ApplyPaletteHash2(pix)]); + } else { + uint32_t idx_map[MAX_PALETTE_SIZE]; + uint32_t palette_sorted[MAX_PALETTE_SIZE]; + PrepareMapToPalette(palette, palette_size, palette_sorted, idx_map); + APPLY_PALETTE_FOR( + idx_map[SearchColorNoIdx(palette_sorted, pix, palette_size)]); } } WebPSafeFree(tmp_row); return VP8_ENC_OK; } +#undef APPLY_PALETTE_FOR +#undef PALETTE_INV_SIZE_BITS +#undef PALETTE_INV_SIZE +#undef APPLY_PALETTE_GREEDY_MAX // Note: Expects "enc->palette_" to be set properly. static WebPEncodingError MapImageFromPalette(VP8LEncoder* const enc,