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Add smart RGB->YUV conversion option -pre 4

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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.

(cherry picked from commit 3fc4c539aa)

Change-Id: Ia50a8c30134e4cab8a7d3eb70aef13ce1f6187a1
This commit is contained in:
skal 2014-08-15 10:55:09 -07:00 committed by James Zern
parent 1a161e20a4
commit 21abaa05e3
4 changed files with 548 additions and 99 deletions
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2
src/enc/config.c
View File

@ -111,7 +111,7 @@ int WebPValidateConfig(const WebPConfig* config) {
return 0; return 0;
if (config->show_compressed < 0 || config->show_compressed > 1) if (config->show_compressed < 0 || config->show_compressed > 1)
return 0; return 0;
if (config->preprocessing < 0 || config->preprocessing > 3) if (config->preprocessing < 0 || config->preprocessing > 7)
return 0; return 0;
if (config->partitions < 0 || config->partitions > 3) if (config->partitions < 0 || config->partitions > 3)
return 0; return 0;

607
src/enc/picture_csp.c
View File

@ -17,6 +17,7 @@
#include "./vp8enci.h" #include "./vp8enci.h"
#include "../utils/random.h" #include "../utils/random.h"
#include "../utils/utils.h"
#include "../dsp/yuv.h" #include "../dsp/yuv.h"
// Uncomment to disable gamma-compression during RGB->U/V averaging // Uncomment to disable gamma-compression during RGB->U/V averaging
@ -69,6 +70,70 @@ int WebPPictureHasTransparency(const WebPPicture* picture) {
return 0; return 0;
} }
//------------------------------------------------------------------------------
// 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 // RGB -> YUV conversion
@ -85,71 +150,423 @@ static int RGBToV(int r, int g, int b, VP8Random* const rg) {
} }
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// 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) #if defined(USE_GAMMA_COMPRESSION)
// gamma-compensates loss of resolution during chroma subsampling // float variant of gamma-correction
#define kGamma 0.80 // We use tables of different size and precision, along with a 'real-world'
#define kGammaFix 12 // fixed-point precision for linear values // Gamma value close to ~2.
#define kGammaScale ((1 << kGammaFix) - 1) #define kGammaF 2.2
#define kGammaTabFix 7 // fixed-point fractional bits precision static float kGammaToLinearTabF[MAX_Y_T + 1]; // size scales with Y_FIX
#define kGammaTabScale (1 << kGammaTabFix) static float kLinearToGammaTabF[kGammaTabSize + 2];
#define kGammaTabRounder (kGammaTabScale >> 1) static int kGammaTablesFOk = 0;
#define kGammaTabSize (1 << (kGammaFix - kGammaTabFix))
static int kLinearToGammaTab[kGammaTabSize + 1]; static void InitGammaTablesF(void) {
static uint16_t kGammaToLinearTab[256]; if (!kGammaTablesFOk) {
static int kGammaTablesOk = 0;
static void InitGammaTables(void) {
if (!kGammaTablesOk) {
int v; int v;
const double scale = 1. / kGammaScale; const double norm = 1. / MAX_Y_T;
for (v = 0; v <= 255; ++v) { const double scale = 1. / kGammaTabSize;
kGammaToLinearTab[v] = for (v = 0; v <= MAX_Y_T; ++v) {
(uint16_t)(pow(v / 255., kGamma) * kGammaScale + .5); kGammaToLinearTabF[v] = (float)pow(norm * v, kGammaF);
} }
for (v = 0; v <= kGammaTabSize; ++v) { for (v = 0; v <= kGammaTabSize; ++v) {
const double x = scale * (v << kGammaTabFix); kLinearToGammaTabF[v] = (float)(MAX_Y_T * pow(scale * v, 1. / kGammaF));
kLinearToGammaTab[v] = (int)(pow(x, 1. / kGamma) * 255. + .5);
} }
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) { static WEBP_INLINE float GammaToLinearF(int v) {
return kGammaToLinearTab[v]; return kGammaToLinearTabF[v];
} }
// Convert a linear value 'v' to YUV_FIX+2 fixed-point precision static WEBP_INLINE float LinearToGammaF(float value) {
// U/V value, suitable for RGBToU/V calls. const float v = value * kGammaTabSize;
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { const int tab_pos = (int)v;
const int v = base_value << shift; // final uplifted value const float x = v - (float)tab_pos; // fractional part
const int tab_pos = v >> (kGammaTabFix + 2); // integer part const float v0 = kLinearToGammaTabF[tab_pos + 0];
const int x = v & ((kGammaTabScale << 2) - 1); // fractional part const float v1 = kLinearToGammaTabF[tab_pos + 1];
const int v0 = kLinearToGammaTab[tab_pos]; const float y = v1 * x + v0 * (1. - x); // interpolate
const int v1 = kLinearToGammaTab[tab_pos + 1]; return y;
const int y = v1 * x + v0 * ((kGammaTabScale << 2) - x); // interpolate
return (y + kGammaTabRounder) >> kGammaTabFix; // descale
} }
#else #else
static void InitGammaTables(void) {} static void InitGammaTablesF(void) {}
static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { return v; } static WEBP_INLINE float GammaToLinearF(int v) {
static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) { const float norm = 1.f / MAX_Y_T;
return (int)(base_value << shift); return norm * v;
}
static WEBP_INLINE float LinearToGammaF(float value) {
return MAX_Y_T * value;
} }
#endif // USE_GAMMA_COMPRESSION #endif // USE_GAMMA_COMPRESSION
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
#define SUM4(ptr) LinearToGamma( \ // precision: YFIX -> TFIX
GammaToLinear((ptr)[0]) + \ static WEBP_INLINE int FixedYToW(int v) {
GammaToLinear((ptr)[step]) + \ #if TFIX == YFIX
GammaToLinear((ptr)[rgb_stride]) + \ return v;
GammaToLinear((ptr)[rgb_stride + step]), 0) \ #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) \ #define SUM2H(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[step]), 1) LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[step]), 1)
@ -158,14 +575,14 @@ static WEBP_INLINE int LinearToGamma(uint32_t base_value, int shift) {
#define SUM1(ptr) \ #define SUM1(ptr) \
LinearToGamma(GammaToLinear((ptr)[0]), 2) LinearToGamma(GammaToLinear((ptr)[0]), 2)
#define RGB_TO_UV(x, y, SUM) { \ #define RGB_TO_UV(x, y, SUM) { \
const int src = (2 * (step * (x) + (y) * rgb_stride)); \ const int src = (2 * (step * (x) + (y) * rgb_stride)); \
const int dst = (x) + (y) * picture->uv_stride; \ const int dst = (x) + (y) * picture->uv_stride; \
const int r = SUM(r_ptr + src); \ const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \ const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \ const int b = SUM(b_ptr + src); \
picture->u[dst] = RGBToU(r, g, b, &rg); \ picture->u[dst] = RGBToU(r, g, b, &rg); \
picture->v[dst] = RGBToV(r, g, b, &rg); \ picture->v[dst] = RGBToV(r, g, b, &rg); \
} }
static int ImportYUVAFromRGBA(const uint8_t* const r_ptr, static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
@ -175,49 +592,56 @@ static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
int step, // bytes per pixel int step, // bytes per pixel
int rgb_stride, // bytes per scanline int rgb_stride, // bytes per scanline
float dithering, float dithering,
int use_iterative_conversion,
WebPPicture* const picture) { WebPPicture* const picture) {
int x, y; int x, y;
const int width = picture->width; const int width = picture->width;
const int height = picture->height; const int height = picture->height;
const int has_alpha = CheckNonOpaque(a_ptr, width, height, step, rgb_stride); const int has_alpha = CheckNonOpaque(a_ptr, width, height, step, rgb_stride);
VP8Random rg;
if (has_alpha) { picture->colorspace = has_alpha ? WEBP_YUV420A : WEBP_YUV420;
picture->colorspace |= WEBP_CSP_ALPHA_BIT;
} else {
picture->colorspace &= WEBP_CSP_UV_MASK;
}
picture->use_argb = 0; picture->use_argb = 0;
if (!WebPPictureAllocYUVA(picture, width, height)) return 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);
}
} }
// Downsample U/V plane if (use_iterative_conversion) {
for (y = 0; y < (height >> 1); ++y) { InitGammaTablesF();
for (x = 0; x < (width >> 1); ++x) { if (!PreprocessARGB(r_ptr, g_ptr, b_ptr, step, rgb_stride, picture)) {
RGB_TO_UV(x, y, SUM4); return 0;
} }
if (width & 1) { } else {
RGB_TO_UV(x, y, SUM2V); 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) { // Downsample U/V plane
for (x = 0; x < (width >> 1); ++x) { for (y = 0; y < (height >> 1); ++y) {
RGB_TO_UV(x, y, SUM2H); 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) { if (height & 1) {
RGB_TO_UV(x, y, SUM1); 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 @@ static int ImportYUVAFromRGBA(const uint8_t* const r_ptr,
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------
// call for ARGB->YUVA conversion // call for ARGB->YUVA conversion
int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace, static int PictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace,
float dithering) { float dithering, int use_iterative_conversion) {
if (picture == NULL) return 0; if (picture == NULL) return 0;
if (picture->argb == NULL) { if (picture->argb == NULL) {
return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER); 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 { } else {
const uint8_t* const argb = (const uint8_t*)picture->argb; const uint8_t* const argb = (const uint8_t*)picture->argb;
const uint8_t* const r = ALPHA_IS_LAST ? argb + 2 : argb + 1; const uint8_t* const r = ALPHA_IS_LAST ? argb + 2 : argb + 1;
@ -255,14 +681,23 @@ int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace,
const uint8_t* const b = ALPHA_IS_LAST ? argb + 0 : argb + 3; const uint8_t* const b = ALPHA_IS_LAST ? argb + 0 : argb + 3;
const uint8_t* const a = ALPHA_IS_LAST ? argb + 3 : argb + 0; 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, 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) { 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 @@ static int Import(WebPPicture* const picture,
if (!picture->use_argb) { if (!picture->use_argb) {
return ImportYUVAFromRGBA(r_ptr, g_ptr, b_ptr, a_ptr, step, rgb_stride, 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; if (!WebPPictureAlloc(picture)) return 0;

26
src/enc/webpenc.c
View File

@ -328,16 +328,22 @@ int WebPEncode(const WebPConfig* config, WebPPicture* pic) {
VP8Encoder* enc = NULL; VP8Encoder* enc = NULL;
if (pic->y == NULL || pic->u == NULL || pic->v == NULL) { if (pic->y == NULL || pic->u == NULL || pic->v == NULL) {
// Make sure we have YUVA samples. // Make sure we have YUVA samples.
float dithering = 0.f; if (config->preprocessing & 4) {
if (config->preprocessing & 2) { if (!WebPPictureSmartARGBToYUVA(pic)) {
const float x = config->quality / 100.f; return 0;
const float x2 = x * x; }
// slowly decreasing from max dithering at low quality (q->0) } else {
// to 0.5 dithering amplitude at high quality (q->100) float dithering = 0.f;
dithering = 1.0f + (0.5f - 1.0f) * x2 * x2; if (config->preprocessing & 2) {
} const float x = config->quality / 100.f;
if (!WebPPictureARGBToYUVADithered(pic, WEBP_YUV420, dithering)) { const float x2 = x * x;
return 0; // 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;
}
} }
} }

12
src/webp/encode.h
View File

@ -446,13 +446,14 @@ WEBP_EXTERN(int) WebPPictureImportBGRA(
WEBP_EXTERN(int) WebPPictureImportBGRX( WEBP_EXTERN(int) WebPPictureImportBGRX(
WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride); 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 // Upon return, picture->use_argb is set to false. The presence of real
// non-opaque transparent values is detected, and 'colorspace' will be // non-opaque transparent values is detected, and 'colorspace' will be
// adjusted accordingly. Note that this method is lossy. // adjusted accordingly. Note that this method is lossy.
// Returns false in case of error. // Returns false in case of error.
WEBP_EXTERN(int) WebPPictureARGBToYUVA(WebPPicture* picture, WEBP_EXTERN(int) WebPPictureARGBToYUVA(WebPPicture* picture,
WebPEncCSP colorspace); WebPEncCSP /*colorspace = WEBP_YUV420*/);
// Same as WebPPictureARGBToYUVA(), but the conversion is done using // Same as WebPPictureARGBToYUVA(), but the conversion is done using
// pseudo-random dithering with a strength 'dithering' between // pseudo-random dithering with a strength 'dithering' between
@ -461,6 +462,13 @@ WEBP_EXTERN(int) WebPPictureARGBToYUVA(WebPPicture* picture,
WEBP_EXTERN(int) WebPPictureARGBToYUVADithered( WEBP_EXTERN(int) WebPPictureARGBToYUVADithered(
WebPPicture* picture, WebPEncCSP colorspace, float dithering); 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. // Converts picture->yuv to picture->argb and sets picture->use_argb to true.
// The input format must be YUV_420 or YUV_420A. // 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 // Note that the use of this method is discouraged if one has access to the