| // Copyright 2010 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. |
| // ----------------------------------------------------------------------------- |
| // |
| // inline YUV<->RGB conversion function |
| // |
| // The exact naming is Y'CbCr, following the ITU-R BT.601 standard. |
| // More information at: http://en.wikipedia.org/wiki/YCbCr |
| // Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16 |
| // U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128 |
| // V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128 |
| // We use 16bit fixed point operations for RGB->YUV conversion (YUV_FIX). |
| // |
| // For the Y'CbCr to RGB conversion, the BT.601 specification reads: |
| // R = 1.164 * (Y-16) + 1.596 * (V-128) |
| // G = 1.164 * (Y-16) - 0.813 * (V-128) - 0.391 * (U-128) |
| // B = 1.164 * (Y-16) + 2.018 * (U-128) |
| // where Y is in the [16,235] range, and U/V in the [16,240] range. |
| // |
| // The fixed-point implementation used here is: |
| // R = (19077 . y + 26149 . v - 14234) >> 6 |
| // G = (19077 . y - 6419 . u - 13320 . v + 8708) >> 6 |
| // B = (19077 . y + 33050 . u - 17685) >> 6 |
| // where the '.' operator is the mulhi_epu16 variant: |
| // a . b = ((a << 8) * b) >> 16 |
| // that preserves 8 bits of fractional precision before final descaling. |
| |
| // Author: Skal (pascal.massimino@gmail.com) |
| |
| #ifndef WEBP_DSP_YUV_H_ |
| #define WEBP_DSP_YUV_H_ |
| |
| #include "src/dsp/dsp.h" |
| #include "src/dec/vp8_dec.h" |
| |
| //------------------------------------------------------------------------------ |
| // YUV -> RGB conversion |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| enum { |
| YUV_FIX = 16, // fixed-point precision for RGB->YUV |
| YUV_HALF = 1 << (YUV_FIX - 1), |
| |
| YUV_FIX2 = 6, // fixed-point precision for YUV->RGB |
| YUV_MASK2 = (256 << YUV_FIX2) - 1 |
| }; |
| |
| //------------------------------------------------------------------------------ |
| // slower on x86 by ~7-8%, but bit-exact with the SSE2/NEON version |
| |
| static WEBP_INLINE int MultHi(int v, int coeff) { // _mm_mulhi_epu16 emulation |
| return (v * coeff) >> 8; |
| } |
| |
| static WEBP_INLINE int VP8Clip8(int v) { |
| return ((v & ~YUV_MASK2) == 0) ? (v >> YUV_FIX2) : (v < 0) ? 0 : 255; |
| } |
| |
| static WEBP_INLINE int VP8YUVToR(int y, int v) { |
| return VP8Clip8(MultHi(y, 19077) + MultHi(v, 26149) - 14234); |
| } |
| |
| static WEBP_INLINE int VP8YUVToG(int y, int u, int v) { |
| return VP8Clip8(MultHi(y, 19077) - MultHi(u, 6419) - MultHi(v, 13320) + 8708); |
| } |
| |
| static WEBP_INLINE int VP8YUVToB(int y, int u) { |
| return VP8Clip8(MultHi(y, 19077) + MultHi(u, 33050) - 17685); |
| } |
| |
| static WEBP_INLINE void VP8YuvToRgb(int y, int u, int v, |
| uint8_t* const rgb) { |
| rgb[0] = VP8YUVToR(y, v); |
| rgb[1] = VP8YUVToG(y, u, v); |
| rgb[2] = VP8YUVToB(y, u); |
| } |
| |
| static WEBP_INLINE void VP8YuvToBgr(int y, int u, int v, |
| uint8_t* const bgr) { |
| bgr[0] = VP8YUVToB(y, u); |
| bgr[1] = VP8YUVToG(y, u, v); |
| bgr[2] = VP8YUVToR(y, v); |
| } |
| |
| static WEBP_INLINE void VP8YuvToRgb565(int y, int u, int v, |
| uint8_t* const rgb) { |
| const int r = VP8YUVToR(y, v); // 5 usable bits |
| const int g = VP8YUVToG(y, u, v); // 6 usable bits |
| const int b = VP8YUVToB(y, u); // 5 usable bits |
| const int rg = (r & 0xf8) | (g >> 5); |
| const int gb = ((g << 3) & 0xe0) | (b >> 3); |
| #if (WEBP_SWAP_16BIT_CSP == 1) |
| rgb[0] = gb; |
| rgb[1] = rg; |
| #else |
| rgb[0] = rg; |
| rgb[1] = gb; |
| #endif |
| } |
| |
| static WEBP_INLINE void VP8YuvToRgba4444(int y, int u, int v, |
| uint8_t* const argb) { |
| const int r = VP8YUVToR(y, v); // 4 usable bits |
| const int g = VP8YUVToG(y, u, v); // 4 usable bits |
| const int b = VP8YUVToB(y, u); // 4 usable bits |
| const int rg = (r & 0xf0) | (g >> 4); |
| const int ba = (b & 0xf0) | 0x0f; // overwrite the lower 4 bits |
| #if (WEBP_SWAP_16BIT_CSP == 1) |
| argb[0] = ba; |
| argb[1] = rg; |
| #else |
| argb[0] = rg; |
| argb[1] = ba; |
| #endif |
| } |
| |
| //----------------------------------------------------------------------------- |
| // Alpha handling variants |
| |
| static WEBP_INLINE void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v, |
| uint8_t* const argb) { |
| argb[0] = 0xff; |
| VP8YuvToRgb(y, u, v, argb + 1); |
| } |
| |
| static WEBP_INLINE void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v, |
| uint8_t* const bgra) { |
| VP8YuvToBgr(y, u, v, bgra); |
| bgra[3] = 0xff; |
| } |
| |
| static WEBP_INLINE void VP8YuvToRgba(uint8_t y, uint8_t u, uint8_t v, |
| uint8_t* const rgba) { |
| VP8YuvToRgb(y, u, v, rgba); |
| rgba[3] = 0xff; |
| } |
| |
| //----------------------------------------------------------------------------- |
| // SSE2 extra functions (mostly for upsampling_sse2.c) |
| |
| #if defined(WEBP_USE_SSE2) |
| |
| // Process 32 pixels and store the result (16b, 24b or 32b per pixel) in *dst. |
| void VP8YuvToRgba32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToRgb32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToBgra32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToBgr32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToArgb32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToRgba444432_SSE2(const uint8_t* y, const uint8_t* u, |
| const uint8_t* v, uint8_t* dst); |
| void VP8YuvToRgb56532_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| |
| #endif // WEBP_USE_SSE2 |
| |
| //----------------------------------------------------------------------------- |
| // SSE41 extra functions (mostly for upsampling_sse41.c) |
| |
| #if defined(WEBP_USE_SSE41) |
| |
| // Process 32 pixels and store the result (16b, 24b or 32b per pixel) in *dst. |
| void VP8YuvToRgb32_SSE41(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| void VP8YuvToBgr32_SSE41(const uint8_t* y, const uint8_t* u, const uint8_t* v, |
| uint8_t* dst); |
| |
| #endif // WEBP_USE_SSE41 |
| |
| //------------------------------------------------------------------------------ |
| // RGB -> YUV conversion |
| |
| // Stub functions that can be called with various rounding values: |
| static WEBP_INLINE int VP8ClipUV(int uv, int rounding) { |
| uv = (uv + rounding + (128 << (YUV_FIX + 2))) >> (YUV_FIX + 2); |
| return ((uv & ~0xff) == 0) ? uv : (uv < 0) ? 0 : 255; |
| } |
| |
| static WEBP_INLINE int VP8RGBToY(int r, int g, int b, int rounding) { |
| const int luma = 16839 * r + 33059 * g + 6420 * b; |
| return (luma + rounding + (16 << YUV_FIX)) >> YUV_FIX; // no need to clip |
| } |
| |
| static WEBP_INLINE int VP8RGBToU(int r, int g, int b, int rounding) { |
| const int u = -9719 * r - 19081 * g + 28800 * b; |
| return VP8ClipUV(u, rounding); |
| } |
| |
| static WEBP_INLINE int VP8RGBToV(int r, int g, int b, int rounding) { |
| const int v = +28800 * r - 24116 * g - 4684 * b; |
| return VP8ClipUV(v, rounding); |
| } |
| |
| #ifdef __cplusplus |
| } // extern "C" |
| #endif |
| |
| #endif /* WEBP_DSP_YUV_H_ */ |