| // Copyright 2014 Google Inc. All Rights Reserved. |
| // |
| // Use of this source code is governed by a BSD-style license |
| // that can be found in the COPYING file in the root of the source |
| // tree. An additional intellectual property rights grant can be found |
| // in the file PATENTS. All contributing project authors may |
| // be found in the AUTHORS file in the root of the source tree. |
| // ----------------------------------------------------------------------------- |
| // |
| // WebPPicture utils for colorspace conversion |
| // |
| // Author: Skal (pascal.massimino@gmail.com) |
| |
| #include <assert.h> |
| #include <stdlib.h> |
| #include <math.h> |
| |
| #include "./vp8enci.h" |
| #include "../utils/random.h" |
| #include "../dsp/yuv.h" |
| |
| // Uncomment to disable gamma-compression during RGB->U/V averaging |
| #define USE_GAMMA_COMPRESSION |
| |
| static const union { |
| uint32_t argb; |
| uint8_t bytes[4]; |
| } test_endian = { 0xff000000u }; |
| #define ALPHA_IS_LAST (test_endian.bytes[3] == 0xff) |
| |
| static WEBP_INLINE uint32_t MakeARGB32(int a, int r, int g, int b) { |
| return (((uint32_t)a << 24) | (r << 16) | (g << 8) | b); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // Detection of non-trivial transparency |
| |
| // Returns true if alpha[] has non-0xff values. |
| static int CheckNonOpaque(const uint8_t* alpha, int width, int height, |
| int x_step, int y_step) { |
| if (alpha == NULL) return 0; |
| while (height-- > 0) { |
| int x; |
| for (x = 0; x < width * x_step; x += x_step) { |
| if (alpha[x] != 0xff) return 1; // TODO(skal): check 4/8 bytes at a time. |
| } |
| alpha += y_step; |
| } |
| return 0; |
| } |
| |
| // Checking for the presence of non-opaque alpha. |
| int WebPPictureHasTransparency(const WebPPicture* picture) { |
| if (picture == NULL) return 0; |
| if (!picture->use_argb) { |
| return CheckNonOpaque(picture->a, picture->width, picture->height, |
| 1, picture->a_stride); |
| } else { |
| int x, y; |
| const uint32_t* argb = picture->argb; |
| if (argb == NULL) return 0; |
| for (y = 0; y < picture->height; ++y) { |
| for (x = 0; x < picture->width; ++x) { |
| if (argb[x] < 0xff000000u) return 1; // test any alpha values != 0xff |
| } |
| argb += picture->argb_stride; |
| } |
| } |
| return 0; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // RGB -> YUV conversion |
| |
| static int RGBToY(int r, int g, int b, VP8Random* const rg) { |
| return VP8RGBToY(r, g, b, VP8RandomBits(rg, YUV_FIX)); |
| } |
| |
| static int RGBToU(int r, int g, int b, VP8Random* const rg) { |
| return VP8RGBToU(r, g, b, VP8RandomBits(rg, YUV_FIX + 2)); |
| } |
| |
| static int RGBToV(int r, int g, int b, VP8Random* const rg) { |
| return VP8RGBToV(r, g, b, VP8RandomBits(rg, YUV_FIX + 2)); |
| } |
| |
| //------------------------------------------------------------------------------ |
| |
| #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)) |
| |
| 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 = 1. / kGammaScale; |
| for (v = 0; v <= 255; ++v) { |
| kGammaToLinearTab[v] = |
| (uint16_t)(pow(v / 255., kGamma) * kGammaScale + .5); |
| } |
| for (v = 0; v <= kGammaTabSize; ++v) { |
| const double x = scale * (v << kGammaTabFix); |
| kLinearToGammaTab[v] = (int)(pow(x, 1. / kGamma) * 255. + .5); |
| } |
| kGammaTablesOk = 1; |
| } |
| } |
| |
| static WEBP_INLINE uint32_t GammaToLinear(uint8_t v) { |
| return kGammaToLinearTab[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 |
| } |
| |
| #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 |
| |
| //------------------------------------------------------------------------------ |
| |
| #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) |
| #define SUM2V(ptr) \ |
| LinearToGamma(GammaToLinear((ptr)[0]) + GammaToLinear((ptr)[rgb_stride]), 1) |
| #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); \ |
| } |
| |
| static int ImportYUVAFromRGBA(const uint8_t* const r_ptr, |
| const uint8_t* const g_ptr, |
| const uint8_t* const b_ptr, |
| const uint8_t* const a_ptr, |
| int step, // bytes per pixel |
| int rgb_stride, // bytes per scanline |
| float dithering, |
| 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->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); |
| } |
| } |
| |
| // 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 (height & 1) { |
| for (x = 0; x < (width >> 1); ++x) { |
| RGB_TO_UV(x, y, SUM2H); |
| } |
| if (width & 1) { |
| RGB_TO_UV(x, y, SUM1); |
| } |
| } |
| |
| if (has_alpha) { |
| assert(step >= 4); |
| assert(picture->a != NULL); |
| for (y = 0; y < height; ++y) { |
| for (x = 0; x < width; ++x) { |
| picture->a[x + y * picture->a_stride] = |
| a_ptr[step * x + y * rgb_stride]; |
| } |
| } |
| } |
| return 1; |
| } |
| |
| #undef SUM4 |
| #undef SUM2V |
| #undef SUM2H |
| #undef SUM1 |
| #undef RGB_TO_UV |
| |
| //------------------------------------------------------------------------------ |
| // call for ARGB->YUVA conversion |
| |
| int WebPPictureARGBToYUVADithered(WebPPicture* picture, WebPEncCSP colorspace, |
| float dithering) { |
| if (picture == NULL) return 0; |
| if (picture->argb == NULL) { |
| return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER); |
| } else { |
| 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 g = ALPHA_IS_LAST ? argb + 1 : argb + 2; |
| 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; |
| return ImportYUVAFromRGBA(r, g, b, a, 4, 4 * picture->argb_stride, |
| dithering, picture); |
| } |
| } |
| |
| int WebPPictureARGBToYUVA(WebPPicture* picture, WebPEncCSP colorspace) { |
| return WebPPictureARGBToYUVADithered(picture, colorspace, 0.f); |
| } |
| |
| //------------------------------------------------------------------------------ |
| // call for YUVA -> ARGB conversion |
| |
| int WebPPictureYUVAToARGB(WebPPicture* picture) { |
| if (picture == NULL) return 0; |
| if (picture->y == NULL || picture->u == NULL || picture->v == NULL) { |
| return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER); |
| } |
| if ((picture->colorspace & WEBP_CSP_ALPHA_BIT) && picture->a == NULL) { |
| return WebPEncodingSetError(picture, VP8_ENC_ERROR_NULL_PARAMETER); |
| } |
| if ((picture->colorspace & WEBP_CSP_UV_MASK) != WEBP_YUV420) { |
| return WebPEncodingSetError(picture, VP8_ENC_ERROR_INVALID_CONFIGURATION); |
| } |
| // Allocate a new argb buffer (discarding the previous one). |
| if (!WebPPictureAllocARGB(picture, picture->width, picture->height)) return 0; |
| picture->use_argb = 1; |
| |
| // Convert |
| { |
| int y; |
| const int width = picture->width; |
| const int height = picture->height; |
| const int argb_stride = 4 * picture->argb_stride; |
| uint8_t* dst = (uint8_t*)picture->argb; |
| const uint8_t *cur_u = picture->u, *cur_v = picture->v, *cur_y = picture->y; |
| WebPUpsampleLinePairFunc upsample = WebPGetLinePairConverter(ALPHA_IS_LAST); |
| |
| // First row, with replicated top samples. |
| upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width); |
| cur_y += picture->y_stride; |
| dst += argb_stride; |
| // Center rows. |
| for (y = 1; y + 1 < height; y += 2) { |
| const uint8_t* const top_u = cur_u; |
| const uint8_t* const top_v = cur_v; |
| cur_u += picture->uv_stride; |
| cur_v += picture->uv_stride; |
| upsample(cur_y, cur_y + picture->y_stride, top_u, top_v, cur_u, cur_v, |
| dst, dst + argb_stride, width); |
| cur_y += 2 * picture->y_stride; |
| dst += 2 * argb_stride; |
| } |
| // Last row (if needed), with replicated bottom samples. |
| if (height > 1 && !(height & 1)) { |
| upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, width); |
| } |
| // Insert alpha values if needed, in replacement for the default 0xff ones. |
| if (picture->colorspace & WEBP_CSP_ALPHA_BIT) { |
| for (y = 0; y < height; ++y) { |
| uint32_t* const argb_dst = picture->argb + y * picture->argb_stride; |
| const uint8_t* const src = picture->a + y * picture->a_stride; |
| int x; |
| for (x = 0; x < width; ++x) { |
| argb_dst[x] = (argb_dst[x] & 0x00ffffffu) | ((uint32_t)src[x] << 24); |
| } |
| } |
| } |
| } |
| return 1; |
| } |
| |
| //------------------------------------------------------------------------------ |
| // automatic import / conversion |
| |
| static int Import(WebPPicture* const picture, |
| const uint8_t* const rgb, int rgb_stride, |
| int step, int swap_rb, int import_alpha) { |
| int y; |
| const uint8_t* const r_ptr = rgb + (swap_rb ? 2 : 0); |
| const uint8_t* const g_ptr = rgb + 1; |
| const uint8_t* const b_ptr = rgb + (swap_rb ? 0 : 2); |
| const uint8_t* const a_ptr = import_alpha ? rgb + 3 : NULL; |
| const int width = picture->width; |
| const int height = picture->height; |
| |
| if (!picture->use_argb) { |
| return ImportYUVAFromRGBA(r_ptr, g_ptr, b_ptr, a_ptr, step, rgb_stride, |
| 0.f /* no dithering */, picture); |
| } |
| if (!WebPPictureAlloc(picture)) return 0; |
| |
| assert(step >= (import_alpha ? 4 : 3)); |
| for (y = 0; y < height; ++y) { |
| uint32_t* const dst = &picture->argb[y * picture->argb_stride]; |
| int x; |
| for (x = 0; x < width; ++x) { |
| const int offset = step * x + y * rgb_stride; |
| dst[x] = MakeARGB32(import_alpha ? a_ptr[offset] : 0xff, |
| r_ptr[offset], g_ptr[offset], b_ptr[offset]); |
| } |
| } |
| return 1; |
| } |
| |
| // Public API |
| |
| int WebPPictureImportRGB(WebPPicture* picture, |
| const uint8_t* rgb, int rgb_stride) { |
| return (picture != NULL) ? Import(picture, rgb, rgb_stride, 3, 0, 0) : 0; |
| } |
| |
| int WebPPictureImportBGR(WebPPicture* picture, |
| const uint8_t* rgb, int rgb_stride) { |
| return (picture != NULL) ? Import(picture, rgb, rgb_stride, 3, 1, 0) : 0; |
| } |
| |
| int WebPPictureImportRGBA(WebPPicture* picture, |
| const uint8_t* rgba, int rgba_stride) { |
| return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 0, 1) : 0; |
| } |
| |
| int WebPPictureImportBGRA(WebPPicture* picture, |
| const uint8_t* rgba, int rgba_stride) { |
| return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 1, 1) : 0; |
| } |
| |
| int WebPPictureImportRGBX(WebPPicture* picture, |
| const uint8_t* rgba, int rgba_stride) { |
| return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 0, 0) : 0; |
| } |
| |
| int WebPPictureImportBGRX(WebPPicture* picture, |
| const uint8_t* rgba, int rgba_stride) { |
| return (picture != NULL) ? Import(picture, rgba, rgba_stride, 4, 1, 0) : 0; |
| } |
| |
| //------------------------------------------------------------------------------ |
