Add smart RGB->YUV conversion option -pre 4 New function: WebPPictureSmartARGBToYUVA() This implement smart RGB->YUV conversion. This is rather undocumented for now, and is triggered using '-pre 4' preprocessing option. This is slow-ish and use quite some memory, but should be improvable. This is somehow a usable beta version. Change-Id: Ia50a8c30134e4cab8a7d3eb70aef13ce1f6187a1
diff --git a/src/enc/config.c b/src/enc/config.c index 34dcbfe..2af8782 100644 --- a/src/enc/config.c +++ b/src/enc/config.c
@@ -112,7 +112,7 @@ return 0; if (config->show_compressed < 0 || config->show_compressed > 1) return 0; - if (config->preprocessing < 0 || config->preprocessing > 3) + if (config->preprocessing < 0 || config->preprocessing > 7) return 0; if (config->partitions < 0 || config->partitions > 3) return 0;
diff --git a/src/enc/picture_csp.c b/src/enc/picture_csp.c index 7964f25..17c392f 100644 --- a/src/enc/picture_csp.c +++ b/src/enc/picture_csp.c
@@ -17,6 +17,7 @@ #include "./vp8enci.h" #include "../utils/random.h" +#include "../utils/utils.h" #include "../dsp/yuv.h" // Uncomment to disable gamma-compression during RGB->U/V averaging @@ -70,6 +71,70 @@ } //------------------------------------------------------------------------------ +// Code for gamma correction + +#if defined(USE_GAMMA_COMPRESSION) + +// gamma-compensates loss of resolution during chroma subsampling +#define kGamma 0.80 // for now we use a different gamma value than kGammaF +#define kGammaFix 12 // fixed-point precision for linear values +#define kGammaScale ((1 << kGammaFix) - 1) +#define kGammaTabFix 7 // fixed-point fractional bits precision +#define kGammaTabScale (1 << kGammaTabFix) +#define kGammaTabRounder (kGammaTabScale >> 1) +#define kGammaTabSize (1 << (kGammaFix - kGammaTabFix)) + +static int kLinearToGammaTab[kGammaTabSize + 1]; +static uint16_t kGammaToLinearTab[256]; +static int kGammaTablesOk = 0; + +static void InitGammaTables(void) { + if (!kGammaTablesOk) { + int v; + const double scale = (double)(1 << kGammaTabFix) / kGammaScale; + const double norm = 1. / 255.; + for (v = 0; v <= 255; ++v) { + kGammaToLinearTab[v] = + (uint16_t)(pow(norm * v, kGamma) * kGammaScale + .5); + } + for (v = 0; v <= kGammaTabSize; ++v) { + kLinearToGammaTab[v] = (int)(255. * pow(scale * v, 1. / kGamma) + .5); + } + kGammaTablesOk = 1; + } +} + +static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { + return kGammaToLinearTab[v]; +} + +static WEBP_INLINE int Interpolate(int v) { + const int tab_pos = v >> (kGammaTabFix + 2); // integer part + const int x = v & ((kGammaTabScale << 2) - 1); // fractional part + const int v0 = kLinearToGammaTab[tab_pos]; + const int v1 = kLinearToGammaTab[tab_pos + 1]; + const int y = v1 * x + v0 * ((kGammaTabScale << 2) - x); // interpolate + return y; +} + +// Convert a linear value 'v' to YUV_FIX+2 fixed-point precision +// U/V value, suitable for RGBToU/V calls. +static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { + const int y = Interpolate(base_value << shift); // final uplifted value + return (y + kGammaTabRounder) >> kGammaTabFix; // descale +} + +#else + +static void InitGammaTables(void) {} +static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { return v; } +static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { + return (int)(base_value << shift); +} + +#endif // USE_GAMMA_COMPRESSION + +//------------------------------------------------------------------------------ // RGB -> YUV conversion static int RGBToY(int r, int g, int b, VP8Random* const rg) { @@ -85,71 +150,423 @@ } //------------------------------------------------------------------------------ +// Smart RGB->YUV conversion + +static const int kNumIterations = 6; + +// We use a-priori a different precision for storing RGB and Y/W components +// We could use YFIX=0 and only uint8_t for fixed_y_t, but it produces some +// banding sometimes. Better use extra precision. +// TODO(skal): cleanup once TFIX/YFIX values are fixed. + +typedef int16_t fixed_t; // signed type with extra TFIX precision for UV +typedef uint16_t fixed_y_t; // unsigned type with extra YFIX precision for W +#define TFIX 6 // fixed-point precision of RGB +#define YFIX 2 // fixed point precision for Y/W + +#define THALF ((1 << TFIX) >> 1) +#define MAX_Y_T ((256 << YFIX) - 1) +#define TROUNDER (1 << (YUV_FIX + TFIX - 1)) #if defined(USE_GAMMA_COMPRESSION) -// gamma-compensates loss of resolution during chroma subsampling -#define kGamma 0.80 -#define kGammaFix 12 // fixed-point precision for linear values -#define kGammaScale ((1 << kGammaFix) - 1) -#define kGammaTabFix 7 // fixed-point fractional bits precision -#define kGammaTabScale (1 << kGammaTabFix) -#define kGammaTabRounder (kGammaTabScale >> 1) -#define kGammaTabSize (1 << (kGammaFix - kGammaTabFix)) +// float variant of gamma-correction +// We use tables of different size and precision, along with a 'real-world' +// Gamma value close to ~2. +#define kGammaF 2.2 +static float kGammaToLinearTabF[MAX_Y_T + 1]; // size scales with Y_FIX +static float kLinearToGammaTabF[kGammaTabSize + 2]; +static int kGammaTablesFOk = 0; -static int kLinearToGammaTab[kGammaTabSize + 1]; -static uint16_t kGammaToLinearTab[256]; -static int kGammaTablesOk = 0; - -static void InitGammaTables(void) { - if (!kGammaTablesOk) { +static void InitGammaTablesF(void) { + if (!kGammaTablesFOk) { int v; - const double scale = 1. / kGammaScale; - for (v = 0; v <= 255; ++v) { - kGammaToLinearTab[v] = - (uint16_t)(pow(v / 255., kGamma) * kGammaScale + .5); + const double norm = 1. / MAX_Y_T; + const double scale = 1. / kGammaTabSize; + for (v = 0; v <= MAX_Y_T; ++v) { + kGammaToLinearTabF[v] = (float)pow(norm * v, kGammaF); } for (v = 0; v <= kGammaTabSize; ++v) { - const double x = scale * (v << kGammaTabFix); - kLinearToGammaTab[v] = (int)(pow(x, 1. / kGamma) * 255. + .5); + kLinearToGammaTabF[v] = (float)(MAX_Y_T * pow(scale * v, 1. / kGammaF)); } - kGammaTablesOk = 1; + // to prevent small rounding errors to cause read-overflow: + kLinearToGammaTabF[kGammaTabSize + 1] = kLinearToGammaTabF[kGammaTabSize]; + kGammaTablesFOk = 1; } } -static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { - return kGammaToLinearTab[v]; +static WEBP_INLINE float GammaToLinearF(int v) { + return kGammaToLinearTabF[v]; } -// Convert a linear value 'v' to YUV_FIX+2 fixed-point precision -// U/V value, suitable for RGBToU/V calls. -static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { - const int v = base_value << shift; // final uplifted value - const int tab_pos = v >> (kGammaTabFix + 2); // integer part - const int x = v & ((kGammaTabScale << 2) - 1); // fractional part - const int v0 = kLinearToGammaTab[tab_pos]; - const int v1 = kLinearToGammaTab[tab_pos + 1]; - const int y = v1 * x + v0 * ((kGammaTabScale << 2) - x); // interpolate - return (y + kGammaTabRounder) >> kGammaTabFix; // descale +static WEBP_INLINE float LinearToGammaF(float value) { + const float v = value * kGammaTabSize; + const int tab_pos = (int)v; + const float x = v - (float)tab_pos; // fractional part + const float v0 = kLinearToGammaTabF[tab_pos + 0]; + const float v1 = kLinearToGammaTabF[tab_pos + 1]; + const float y = v1 * x + v0 * (1. - x); // interpolate + return y; } #else -static void InitGammaTables(void) {} -static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { return v; } -static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { - return (int)(base_value << shift); +static void InitGammaTablesF(void) {} +static WEBP_INLINE float GammaToLinearF(int v) { + const float norm = 1.f / MAX_Y_T; + return norm * v; +} +static WEBP_INLINE float LinearToGammaF(float value) { + return MAX_Y_T * value; } #endif // USE_GAMMA_COMPRESSION //------------------------------------------------------------------------------ -#define SUM4(ptr) LinearToGamma( \ - GammaToLinear((ptr)[0]) + \ - GammaToLinear((ptr)[step]) + \ - GammaToLinear((ptr)[rgb_stride]) + \ - GammaToLinear((ptr)[rgb_stride + step]), 0) \ +// precision: YFIX -> TFIX +static WEBP_INLINE int FixedYToW(int v) { +#if TFIX == YFIX + return v; +#elif TFIX >= YFIX + return v << (TFIX - YFIX); +#else + return v >> (YFIX - TFIX); +#endif +} + +static WEBP_INLINE int FixedWToY(int v) { +#if TFIX == YFIX + return v; +#elif YFIX >= TFIX + return v << (YFIX - TFIX); +#else + return v >> (TFIX - YFIX); +#endif +} + +static uint8_t clip_8b(fixed_t v) { + return (!(v & ~0xff)) ? (uint8_t)v : (v < 0) ? 0u : 255u; +} + +static fixed_y_t clip_y(int y) { + return (!(y & ~MAX_Y_T)) ? (fixed_y_t)y : (y < 0) ? 0 : MAX_Y_T; +} + +// precision: TFIX -> YFIX +static fixed_y_t clip_fixed_t(fixed_t v) { + const int y = FixedWToY(v); + const fixed_y_t w = clip_y(y); + return w; +} + +//------------------------------------------------------------------------------ + +static int RGBToGray(int r, int g, int b) { + const int luma = 19595 * r + 38470 * g + 7471 * b + YUV_HALF; + return (luma >> YUV_FIX); +} + +static float RGBToGrayF(float r, float g, float b) { + return 0.299f * r + 0.587f * g + 0.114f * b; +} + +static float ScaleDown(int a, int b, int c, int d) { + const float A = GammaToLinearF(a); + const float B = GammaToLinearF(b); + const float C = GammaToLinearF(c); + const float D = GammaToLinearF(d); + return LinearToGammaF(0.25f * (A + B + C + D)); +} + +static WEBP_INLINE void UpdateW(const fixed_y_t* src, fixed_y_t* dst, int len) { + while (len-- > 0) { + const float R = GammaToLinearF(src[0]); + const float G = GammaToLinearF(src[1]); + const float B = GammaToLinearF(src[2]); + const float Y = RGBToGrayF(R, G, B); + *dst++ = (fixed_y_t)(LinearToGammaF(Y) + .5); + src += 3; + } +} + +static WEBP_INLINE void UpdateChroma(const fixed_y_t* src1, + const fixed_y_t* src2, + fixed_t* dst, fixed_y_t* tmp, int len) { + while (len--> 0) { + const float r = ScaleDown(src1[0], src1[3], src2[0], src2[3]); + const float g = ScaleDown(src1[1], src1[4], src2[1], src2[4]); + const float b = ScaleDown(src1[2], src1[5], src2[2], src2[5]); + const float W = RGBToGrayF(r, g, b); + dst[0] = (fixed_t)FixedYToW(r - W); + dst[1] = (fixed_t)FixedYToW(g - W); + dst[2] = (fixed_t)FixedYToW(b - W); + dst += 3; + src1 += 6; + src2 += 6; + if (tmp != NULL) { + tmp[0] = tmp[1] = clip_y((int)(W + .5)); + tmp += 2; + } + } +} + +//------------------------------------------------------------------------------ + +static WEBP_INLINE int Filter(const fixed_t* const A, const fixed_t* const B, + int rightwise) { + int v; + if (!rightwise) { + v = (A[0] * 9 + A[-3] * 3 + B[0] * 3 + B[-3]); + } else { + v = (A[0] * 9 + A[+3] * 3 + B[0] * 3 + B[+3]); + } + return (v + 8) >> 4; +} + +static WEBP_INLINE int Filter2(int A, int B) { return (A * 3 + B + 2) >> 2; } + +//------------------------------------------------------------------------------ + +// 8bit -> YFIX +static WEBP_INLINE fixed_y_t UpLift(uint8_t a) { + return ((fixed_y_t)a << YFIX) | (1 << (YFIX - 1)); +} + +static void ImportOneRow(const uint8_t* const r_ptr, + const uint8_t* const g_ptr, + const uint8_t* const b_ptr, + int step, + int pic_width, + fixed_y_t* const dst) { + int i; + for (i = 0; i < pic_width; ++i) { + const int off = i * step; + dst[3 * i + 0] = UpLift(r_ptr[off]); + dst[3 * i + 1] = UpLift(g_ptr[off]); + dst[3 * i + 2] = UpLift(b_ptr[off]); + } +} + +static void InterpolateTwoRows(const fixed_y_t* const best_y, + const fixed_t* const prev_uv, + const fixed_t* const cur_uv, + const fixed_t* const next_uv, + int w, + fixed_y_t* const out1, + fixed_y_t* const out2) { + int i, k; + { // special boundary case for i==0 + const int W0 = FixedYToW(best_y[0]); + const int W1 = FixedYToW(best_y[w]); + for (k = 0; k <= 2; ++k) { + out1[k] = clip_fixed_t(Filter2(cur_uv[k], prev_uv[k]) + W0); + out2[k] = clip_fixed_t(Filter2(cur_uv[k], next_uv[k]) + W1); + } + } + for (i = 1; i < w - 1; ++i) { + const int W0 = FixedYToW(best_y[i + 0]); + const int W1 = FixedYToW(best_y[i + w]); + const int off = 3 * (i >> 1); + for (k = 0; k <= 2; ++k) { + const int tmp0 = Filter(cur_uv + off + k, prev_uv + off + k, i & 1); + const int tmp1 = Filter(cur_uv + off + k, next_uv + off + k, i & 1); + out1[3 * i + k] = clip_fixed_t(tmp0 + W0); + out2[3 * i + k] = clip_fixed_t(tmp1 + W1); + } + } + { // special boundary case for i == w - 1 + const int W0 = FixedYToW(best_y[i + 0]); + const int W1 = FixedYToW(best_y[i + w]); + const int off = 3 * (i >> 1); + for (k = 0; k <= 2; ++k) { + out1[3 * i + k] = + clip_fixed_t(Filter2(cur_uv[off + k], prev_uv[off + k]) + W0); + out2[3 * i + k] = + clip_fixed_t(Filter2(cur_uv[off + k], next_uv[off + k]) + W1); + } + } +} + +static WEBP_INLINE uint8_t ConvertRGBToY(int r, int g, int b) { + const int luma = 16839 * r + 33059 * g + 6420 * b + TROUNDER; + return clip_8b(16 + (luma >> (YUV_FIX + TFIX))); +} + +static WEBP_INLINE uint8_t ConvertRGBToU(int r, int g, int b) { + const int u = -9719 * r - 19081 * g + 28800 * b + TROUNDER; + return clip_8b(128 + (u >> (YUV_FIX + TFIX))); +} + +static WEBP_INLINE uint8_t ConvertRGBToV(int r, int g, int b) { + const int v = +28800 * r - 24116 * g - 4684 * b + TROUNDER; + return clip_8b(128 + (v >> (YUV_FIX + TFIX))); +} + +static int ConvertWRGBToYUV(const fixed_y_t* const best_y, + const fixed_t* const best_uv, + WebPPicture* const picture) { + int i, j; + const int w = (picture->width + 1) & ~1; + const int h = (picture->height + 1) & ~1; + const int uv_w = w >> 1; + const int uv_h = h >> 1; + for (j = 0; j < picture->height; ++j) { + for (i = 0; i < picture->width; ++i) { + const int off = 3 * ((i >> 1) + (j >> 1) * uv_w); + const int off2 = i + j * picture->y_stride; + const int W = FixedYToW(best_y[i + j * w]); + const int r = best_uv[off + 0] + W; + const int g = best_uv[off + 1] + W; + const int b = best_uv[off + 2] + W; + picture->y[off2] = ConvertRGBToY(r, g, b); + } + } + for (j = 0; j < uv_h; ++j) { + uint8_t* const dst_u = picture->u + j * picture->uv_stride; + uint8_t* const dst_v = picture->v + j * picture->uv_stride; + for (i = 0; i < uv_w; ++i) { + const int off = 3 * (i + j * uv_w); + const int r = best_uv[off + 0]; + const int g = best_uv[off + 1]; + const int b = best_uv[off + 2]; + dst_u[i] = ConvertRGBToU(r, g, b); + dst_v[i] = ConvertRGBToV(r, g, b); + } + } + return 1; +} + + +//------------------------------------------------------------------------------ +// Main function + +#define SAFE_ALLOC(W, H, T) ((T*)WebPSafeMalloc((W) * (H), sizeof(T))) + +static int PreprocessARGB(const uint8_t* const r_ptr, + const uint8_t* const g_ptr, + const uint8_t* const b_ptr, + int step, int rgb_stride, + WebPPicture* const picture) { + // we expand the right/bottom border if needed + const int w = (picture->width + 1) & ~1; + const int h = (picture->height + 1) & ~1; + const int uv_w = w >> 1; + const int uv_h = h >> 1; + int i, j, iter; + + // TODO(skal): allocate one big memory chunk. But for now, it's easier + // for valgrind debugging to have several chunks. + fixed_y_t* const tmp_buffer = SAFE_ALLOC(w * 3, 2, fixed_y_t); // scratch + fixed_y_t* const best_y = SAFE_ALLOC(w, h, fixed_y_t); + fixed_y_t* const target_y = SAFE_ALLOC(w, h, fixed_y_t); + fixed_y_t* const best_rgb_y = SAFE_ALLOC(w, 2, fixed_y_t); + fixed_t* const best_uv = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t); + fixed_t* const target_uv = SAFE_ALLOC(uv_w * 3, uv_h, fixed_t); + fixed_t* const best_rgb_uv = SAFE_ALLOC(uv_w * 3, 1, fixed_t); + int ok; + + if (best_y == NULL || best_uv == NULL || + target_y == NULL || target_uv == NULL || + best_rgb_y == NULL || best_rgb_uv == NULL || + tmp_buffer == NULL) { + ok = WebPEncodingSetError(picture, VP8_ENC_ERROR_OUT_OF_MEMORY); + goto End; + } + + // Import RGB samples to W/RGB representation. + for (j = 0; j < picture->height; j += 2) { + const int is_last_row = (j == picture->height - 1); + fixed_y_t* const src1 = tmp_buffer; + fixed_y_t* const src2 = tmp_buffer + 3 * w; + const int off1 = j * rgb_stride; + const int off2 = off1 + rgb_stride; + const int uv_off = (j >> 1) * 3 * uv_w; + fixed_y_t* const dst_y = best_y + j * w; + + // prepare two rows of input + ImportOneRow(r_ptr + off1, g_ptr + off1, b_ptr + off1, + step, picture->width, src1); + if (!is_last_row) { + ImportOneRow(r_ptr + off2, g_ptr + off2, b_ptr + off2, + step, picture->width, src2); + } else { + memcpy(src2, src1, 3 * w * sizeof(*src2)); + } + UpdateW(src1, target_y + (j + 0) * w, w); + UpdateW(src2, target_y + (j + 1) * w, w); + UpdateChroma(src1, src2, target_uv + uv_off, dst_y, uv_w); + memcpy(best_uv + uv_off, target_uv + uv_off, 3 * uv_w * sizeof(*best_uv)); + memcpy(dst_y + w, dst_y, w * sizeof(*dst_y)); + } + + // Iterate and resolve clipping conflicts. + for (iter = 0; iter < kNumIterations; ++iter) { + int k; + const fixed_t* cur_uv = best_uv; + const fixed_t* prev_uv = best_uv; + for (j = 0; j < h; j += 2) { + fixed_y_t* const src1 = tmp_buffer; + fixed_y_t* const src2 = tmp_buffer + 3 * w; + + { + const fixed_t* const next_uv = cur_uv + ((j < h - 2) ? 3 * uv_w : 0); + InterpolateTwoRows(best_y + j * w, prev_uv, cur_uv, next_uv, + w, src1, src2); + prev_uv = cur_uv; + cur_uv = next_uv; + } + + UpdateW(src1, best_rgb_y + 0 * w, w); + UpdateW(src2, best_rgb_y + 1 * w, w); + UpdateChroma(src1, src2, best_rgb_uv, NULL, uv_w); + + // update two rows of Y and one row of RGB + for (i = 0; i < 2 * w; ++i) { + const int off = i + j * w; + const int diff_y = target_y[off] - best_rgb_y[i]; + const int new_y = (int)best_y[off] + diff_y; + best_y[off] = clip_y(new_y); + } + for (i = 0; i < uv_w; ++i) { + const int off = 3 * (i + (j >> 1) * uv_w); + int W; + for (k = 0; k <= 2; ++k) { + const int diff_uv = (int)target_uv[off + k] - best_rgb_uv[3 * i + k]; + best_uv[off + k] += diff_uv; + } + W = RGBToGray(best_uv[off + 0], best_uv[off + 1], best_uv[off + 2]); + for (k = 0; k <= 2; ++k) { + best_uv[off + k] -= W; + } + } + } + // TODO(skal): add early-termination criterion + } + + // final reconstruction + ok = ConvertWRGBToYUV(best_y, best_uv, picture); + + End: + WebPSafeFree(best_y); + WebPSafeFree(best_uv); + WebPSafeFree(target_y); + WebPSafeFree(target_uv); + WebPSafeFree(best_rgb_y); + WebPSafeFree(best_rgb_uv); + WebPSafeFree(tmp_buffer); + return ok; +} +#undef SAFE_ALLOC + +//------------------------------------------------------------------------------ +// "Fast" regular RGB->YUV + +#define SUM4(ptr) LinearToGamma( \ + GammaToLinear((ptr)[0]) + \ + GammaToLinear((ptr)[step]) + \ + GammaToLinear((ptr)[rgb_stride]) + \ + GammaToLinear((ptr)[rgb_stride + step]), 0) \ #define SUM2H(ptr) \ LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[step]), 1) @@ -158,14 +575,14 @@ #define SUM1(ptr) \ LinearToGamma(GammaToLinear((ptr)[0]), 2) -#define RGB_TO_UV(x, y, SUM) { \ - const int src = (2 * (step * (x) + (y) * rgb_stride)); \ - const int dst = (x) + (y) * picture->uv_stride; \ - const int r = SUM(r_ptr + src); \ - const int g = SUM(g_ptr + src); \ - const int b = SUM(b_ptr + src); \ - picture->u[dst] = RGBToU(r, g, b, &rg); \ - picture->v[dst] = RGBToV(r, g, b, &rg); \ +#define RGB_TO_UV(x, y, SUM) { \ + const int src = (2 * (step * (x) + (y) * rgb_stride)); \ + const int dst = (x) + (y) * picture->uv_stride; \ + const int r = SUM(r_ptr + src); \ + const int g = SUM(g_ptr + src); \ + const int b = SUM(b_ptr + src); \ + picture->u[dst] = RGBToU(r, g, b, &rg); \ + picture->v[dst] = RGBToV(r, g, b, &rg); \ } static int ImportYUVAFromRGBA(const uint8_t* const r_ptr, @@ -175,49 +592,56 @@ int step, // bytes per pixel int rgb_stride, // bytes per scanline float dithering, + int use_iterative_conversion, WebPPicture* const picture) { int x, y; const int width = picture->width; const int height = picture->height; const int has_alpha = CheckNonOpaque(a_ptr, width, height, step, rgb_stride); - VP8Random rg; - if (has_alpha) { - picture->colorspace |= WEBP_CSP_ALPHA_BIT; - } else { - picture->colorspace &= WEBP_CSP_UV_MASK; - } + picture->colorspace = has_alpha ? WEBP_YUV420A : WEBP_YUV420; picture->use_argb = 0; - if (!WebPPictureAllocYUVA(picture, width, height)) return 0; - - VP8InitRandom(&rg, dithering); - InitGammaTables(); - - // Import luma plane - for (y = 0; y < height; ++y) { - uint8_t* const dst = &picture->y[y * picture->y_stride]; - for (x = 0; x < width; ++x) { - const int offset = step * x + y * rgb_stride; - dst[x] = RGBToY(r_ptr[offset], g_ptr[offset], b_ptr[offset], &rg); - } + if (!WebPPictureAllocYUVA(picture, width, height)) { + return 0; } - // Downsample U/V plane - for (y = 0; y < (height >> 1); ++y) { - for (x = 0; x < (width >> 1); ++x) { - RGB_TO_UV(x, y, SUM4); + if (use_iterative_conversion) { + InitGammaTablesF(); + if (!PreprocessARGB(r_ptr, g_ptr, b_ptr, step, rgb_stride, picture)) { + return 0; } - if (width & 1) { - RGB_TO_UV(x, y, SUM2V); + } else { + VP8Random rg; + VP8InitRandom(&rg, dithering); + + InitGammaTables(); + + // Import luma plane + for (y = 0; y < height; ++y) { + uint8_t* const dst = &picture->y[y * picture->y_stride]; + for (x = 0; x < width; ++x) { + const int offset = step * x + y * rgb_stride; + dst[x] = RGBToY(r_ptr[offset], g_ptr[offset], b_ptr[offset], &rg); + } } - } - if (height & 1) { - for (x = 0; x < (width >> 1); ++x) { - RGB_TO_UV(x, y, SUM2H); + + // Downsample U/V plane + for (y = 0; y < (height >> 1); ++y) { + for (x = 0; x < (width >> 1); ++x) { + RGB_TO_UV(x, y, SUM4); + } + if (width & 1) { + RGB_TO_UV(x, y, SUM2V); + } } - if (width & 1) { - RGB_TO_UV(x, y, SUM1); + if (height & 1) { + for (x = 0; x < (width >> 1); ++x) { + RGB_TO_UV(x, y, SUM2H); + } + if (width & 1) { + RGB_TO_UV(x, y, SUM1); + } } } @@ -243,11 +667,13 @@ //------------------------------------------------------------------------------ // call for ARGB->YUVA conversion -int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace, - float dithering) { +static int PictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace, + float dithering, int use_iterative_conversion) { if (picture == NULL) return 0; if (picture->argb == NULL) { return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER); + } else if ((colorspace & WEBP_CSP_UV_MASK) != WEBP_YUV420) { + return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION); } else { const uint8_t* const argb = (const uint8_t*)picture->argb; const uint8_t* const r = ALPHA_IS_LAST ? argb + 2 : argb + 1; @@ -255,14 +681,23 @@ const uint8_t* const b = ALPHA_IS_LAST ? argb + 0 : argb + 3; const uint8_t* const a = ALPHA_IS_LAST ? argb + 3 : argb + 0; - picture->colorspace = colorspace; + picture->colorspace = WEBP_YUV420; return ImportYUVAFromRGBA(r, g, b, a, 4, 4 * picture->argb_stride, - dithering, picture); + dithering, use_iterative_conversion, picture); } } +int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace, + float dithering) { + return PictureARGBToYUVA(picture, colorspace, dithering, 0); +} + int WebPPictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace) { - return WebPPictureARGBToYUVADithered(picture, colorspace, 0.f); + return PictureARGBToYUVA(picture, colorspace, 0.f, 0); +} + +int WebPPictureSmartARGBToYUVA(WebPPicture* picture) { + return PictureARGBToYUVA(picture, WEBP_YUV420, 0.f, 1); } //------------------------------------------------------------------------------ @@ -343,7 +778,7 @@ if (!picture->use_argb) { return ImportYUVAFromRGBA(r_ptr, g_ptr, b_ptr, a_ptr, step, rgb_stride, - 0.f /* no dithering */, picture); + 0.f /* no dithering */, 0, picture); } if (!WebPPictureAlloc(picture)) return 0;
diff --git a/src/enc/webpenc.c b/src/enc/webpenc.c index 20a11d7..5b01e9e 100644 --- a/src/enc/webpenc.c +++ b/src/enc/webpenc.c
@@ -328,16 +328,22 @@ VP8Encoder* enc = NULL; if (pic->y == NULL || pic->u == NULL || pic->v == NULL) { // Make sure we have YUVA samples. - float dithering = 0.f; - if (config->preprocessing & 2) { - const float x = config->quality / 100.f; - const float x2 = x * x; - // slowly decreasing from max dithering at low quality (q->0) - // to 0.5 dithering amplitude at high quality (q->100) - dithering = 1.0f + (0.5f - 1.0f) * x2 * x2; - } - if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) { - return 0; + if (config->preprocessing & 4) { + if (!WebPPictureSmartARGBToYUVA(pic)) { + return 0; + } + } else { + float dithering = 0.f; + if (config->preprocessing & 2) { + const float x = config->quality / 100.f; + const float x2 = x * x; + // slowly decreasing from max dithering at low quality (q->0) + // to 0.5 dithering amplitude at high quality (q->100) + dithering = 1.0f + (0.5f - 1.0f) * x2 * x2; + } + if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) { + return 0; + } } }
diff --git a/src/webp/encode.h b/src/webp/encode.h index c23db20..6947318 100644 --- a/src/webp/encode.h +++ b/src/webp/encode.h
@@ -441,13 +441,14 @@ WEBP_EXTERN(int) WebPPictureImportBGRX( WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride); -// Converts picture->argb data to the YUVA format specified by 'colorspace'. +// Converts picture->argb data to the YUV420A format. The 'colorspace' +// parameter is deprecated and should be equal to WEBP_YUV420. // Upon return, picture->use_argb is set to false. The presence of real // non-opaque transparent values is detected, and 'colorspace' will be // adjusted accordingly. Note that this method is lossy. // Returns false in case of error. WEBP_EXTERN(int) WebPPictureARGBToYUVA(WebPPicture* picture, - WebPEncCSP colorspace); + WebPEncCSP /*colorspace = WEBP_YUV420*/); // Same as WebPPictureARGBToYUVA(), but the conversion is done using // pseudo-random dithering with a strength 'dithering' between @@ -456,6 +457,13 @@ WEBP_EXTERN(int) WebPPictureARGBToYUVADithered( WebPPicture* picture, WebPEncCSP colorspace, float dithering); +// Performs 'smart' RGBA->YUVA420 downsampling and colorspace conversion. +// Downsampling is handled with extra care in case of color clipping. This +// method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better +// YUV representation. +// Returns false in case of error. +WEBP_EXTERN(int) WebPPictureSmartARGBToYUVA(WebPPicture* picture); + // Converts picture->yuv to picture->argb and sets picture->use_argb to true. // The input format must be YUV_420 or YUV_420A. // Note that the use of this method is discouraged if one has access to the