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Diffstat (limited to 'thirdparty/libwebp/src/dsp/yuv.h')
| -rw-r--r-- | thirdparty/libwebp/src/dsp/yuv.h | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/thirdparty/libwebp/src/dsp/yuv.h b/thirdparty/libwebp/src/dsp/yuv.h new file mode 100644 index 0000000000..c8a55832d4 --- /dev/null +++ b/thirdparty/libwebp/src/dsp/yuv.h @@ -0,0 +1,197 @@ +// 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 + +//------------------------------------------------------------------------------ +// 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_ */ |