1 // Copyright 2010 Google Inc. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the COPYING file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 // -----------------------------------------------------------------------------
9 //
10 // inline YUV<->RGB conversion function
11 //
12 // The exact naming is Y'CbCr, following the ITU-R BT.601 standard.
13 // More information at: https://en.wikipedia.org/wiki/YCbCr
14 // Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16
15 // U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128
16 // V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128
17 // We use 16bit fixed point operations for RGB->YUV conversion (YUV_FIX).
18 //
19 // For the Y'CbCr to RGB conversion, the BT.601 specification reads:
20 // R = 1.164 * (Y-16) + 1.596 * (V-128)
21 // G = 1.164 * (Y-16) - 0.813 * (V-128) - 0.391 * (U-128)
22 // B = 1.164 * (Y-16) + 2.018 * (U-128)
23 // where Y is in the [16,235] range, and U/V in the [16,240] range.
24 //
25 // The fixed-point implementation used here is:
26 // R = (19077 . y + 26149 . v - 14234) >> 6
27 // G = (19077 . y - 6419 . u - 13320 . v + 8708) >> 6
28 // B = (19077 . y + 33050 . u - 17685) >> 6
29 // where the '.' operator is the mulhi_epu16 variant:
30 // a . b = ((a << 8) * b) >> 16
31 // that preserves 8 bits of fractional precision before final descaling.
32
33 // Author: Skal (pascal.massimino@gmail.com)
34
35 #ifndef WEBP_DSP_YUV_H_
36 #define WEBP_DSP_YUV_H_
37
38 #include "src/dsp/dsp.h"
39 #include "src/dec/vp8_dec.h"
40
41 //------------------------------------------------------------------------------
42 // YUV -> RGB conversion
43
44 #ifdef __cplusplus
45 extern "C" {
46 #endif
47
48 enum {
49 YUV_FIX = 16, // fixed-point precision for RGB->YUV
50 YUV_HALF = 1 << (YUV_FIX - 1),
51
52 YUV_FIX2 = 6, // fixed-point precision for YUV->RGB
53 YUV_MASK2 = (256 << YUV_FIX2) - 1
54 };
55
56 //------------------------------------------------------------------------------
57 // slower on x86 by ~7-8%, but bit-exact with the SSE2/NEON version
58
MultHi(int v,int coeff)59 static WEBP_INLINE int MultHi(int v, int coeff) { // _mm_mulhi_epu16 emulation
60 return (v * coeff) >> 8;
61 }
62
VP8Clip8(int v)63 static WEBP_INLINE int VP8Clip8(int v) {
64 return ((v & ~YUV_MASK2) == 0) ? (v >> YUV_FIX2) : (v < 0) ? 0 : 255;
65 }
66
VP8YUVToR(int y,int v)67 static WEBP_INLINE int VP8YUVToR(int y, int v) {
68 return VP8Clip8(MultHi(y, 19077) + MultHi(v, 26149) - 14234);
69 }
70
VP8YUVToG(int y,int u,int v)71 static WEBP_INLINE int VP8YUVToG(int y, int u, int v) {
72 return VP8Clip8(MultHi(y, 19077) - MultHi(u, 6419) - MultHi(v, 13320) + 8708);
73 }
74
VP8YUVToB(int y,int u)75 static WEBP_INLINE int VP8YUVToB(int y, int u) {
76 return VP8Clip8(MultHi(y, 19077) + MultHi(u, 33050) - 17685);
77 }
78
VP8YuvToRgb(int y,int u,int v,uint8_t * const rgb)79 static WEBP_INLINE void VP8YuvToRgb(int y, int u, int v,
80 uint8_t* const rgb) {
81 rgb[0] = VP8YUVToR(y, v);
82 rgb[1] = VP8YUVToG(y, u, v);
83 rgb[2] = VP8YUVToB(y, u);
84 }
85
VP8YuvToBgr(int y,int u,int v,uint8_t * const bgr)86 static WEBP_INLINE void VP8YuvToBgr(int y, int u, int v,
87 uint8_t* const bgr) {
88 bgr[0] = VP8YUVToB(y, u);
89 bgr[1] = VP8YUVToG(y, u, v);
90 bgr[2] = VP8YUVToR(y, v);
91 }
92
VP8YuvToRgb565(int y,int u,int v,uint8_t * const rgb)93 static WEBP_INLINE void VP8YuvToRgb565(int y, int u, int v,
94 uint8_t* const rgb) {
95 const int r = VP8YUVToR(y, v); // 5 usable bits
96 const int g = VP8YUVToG(y, u, v); // 6 usable bits
97 const int b = VP8YUVToB(y, u); // 5 usable bits
98 const int rg = (r & 0xf8) | (g >> 5);
99 const int gb = ((g << 3) & 0xe0) | (b >> 3);
100 #if (WEBP_SWAP_16BIT_CSP == 1)
101 rgb[0] = gb;
102 rgb[1] = rg;
103 #else
104 rgb[0] = rg;
105 rgb[1] = gb;
106 #endif
107 }
108
VP8YuvToRgba4444(int y,int u,int v,uint8_t * const argb)109 static WEBP_INLINE void VP8YuvToRgba4444(int y, int u, int v,
110 uint8_t* const argb) {
111 const int r = VP8YUVToR(y, v); // 4 usable bits
112 const int g = VP8YUVToG(y, u, v); // 4 usable bits
113 const int b = VP8YUVToB(y, u); // 4 usable bits
114 const int rg = (r & 0xf0) | (g >> 4);
115 const int ba = (b & 0xf0) | 0x0f; // overwrite the lower 4 bits
116 #if (WEBP_SWAP_16BIT_CSP == 1)
117 argb[0] = ba;
118 argb[1] = rg;
119 #else
120 argb[0] = rg;
121 argb[1] = ba;
122 #endif
123 }
124
125 //-----------------------------------------------------------------------------
126 // Alpha handling variants
127
VP8YuvToArgb(uint8_t y,uint8_t u,uint8_t v,uint8_t * const argb)128 static WEBP_INLINE void VP8YuvToArgb(uint8_t y, uint8_t u, uint8_t v,
129 uint8_t* const argb) {
130 argb[0] = 0xff;
131 VP8YuvToRgb(y, u, v, argb + 1);
132 }
133
VP8YuvToBgra(uint8_t y,uint8_t u,uint8_t v,uint8_t * const bgra)134 static WEBP_INLINE void VP8YuvToBgra(uint8_t y, uint8_t u, uint8_t v,
135 uint8_t* const bgra) {
136 VP8YuvToBgr(y, u, v, bgra);
137 bgra[3] = 0xff;
138 }
139
VP8YuvToRgba(uint8_t y,uint8_t u,uint8_t v,uint8_t * const rgba)140 static WEBP_INLINE void VP8YuvToRgba(uint8_t y, uint8_t u, uint8_t v,
141 uint8_t* const rgba) {
142 VP8YuvToRgb(y, u, v, rgba);
143 rgba[3] = 0xff;
144 }
145
146 //-----------------------------------------------------------------------------
147 // SSE2 extra functions (mostly for upsampling_sse2.c)
148
149 #if defined(WEBP_USE_SSE2)
150
151 // Process 32 pixels and store the result (16b, 24b or 32b per pixel) in *dst.
152 void VP8YuvToRgba32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
153 uint8_t* dst);
154 void VP8YuvToRgb32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
155 uint8_t* dst);
156 void VP8YuvToBgra32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
157 uint8_t* dst);
158 void VP8YuvToBgr32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
159 uint8_t* dst);
160 void VP8YuvToArgb32_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
161 uint8_t* dst);
162 void VP8YuvToRgba444432_SSE2(const uint8_t* y, const uint8_t* u,
163 const uint8_t* v, uint8_t* dst);
164 void VP8YuvToRgb56532_SSE2(const uint8_t* y, const uint8_t* u, const uint8_t* v,
165 uint8_t* dst);
166
167 #endif // WEBP_USE_SSE2
168
169 //-----------------------------------------------------------------------------
170 // SSE41 extra functions (mostly for upsampling_sse41.c)
171
172 #if defined(WEBP_USE_SSE41)
173
174 // Process 32 pixels and store the result (16b, 24b or 32b per pixel) in *dst.
175 void VP8YuvToRgb32_SSE41(const uint8_t* y, const uint8_t* u, const uint8_t* v,
176 uint8_t* dst);
177 void VP8YuvToBgr32_SSE41(const uint8_t* y, const uint8_t* u, const uint8_t* v,
178 uint8_t* dst);
179
180 #endif // WEBP_USE_SSE41
181
182 //------------------------------------------------------------------------------
183 // RGB -> YUV conversion
184
185 // Stub functions that can be called with various rounding values:
VP8ClipUV(int uv,int rounding)186 static WEBP_INLINE int VP8ClipUV(int uv, int rounding) {
187 uv = (uv + rounding + (128 << (YUV_FIX + 2))) >> (YUV_FIX + 2);
188 return ((uv & ~0xff) == 0) ? uv : (uv < 0) ? 0 : 255;
189 }
190
VP8RGBToY(int r,int g,int b,int rounding)191 static WEBP_INLINE int VP8RGBToY(int r, int g, int b, int rounding) {
192 const int luma = 16839 * r + 33059 * g + 6420 * b;
193 return (luma + rounding + (16 << YUV_FIX)) >> YUV_FIX; // no need to clip
194 }
195
VP8RGBToU(int r,int g,int b,int rounding)196 static WEBP_INLINE int VP8RGBToU(int r, int g, int b, int rounding) {
197 const int u = -9719 * r - 19081 * g + 28800 * b;
198 return VP8ClipUV(u, rounding);
199 }
200
VP8RGBToV(int r,int g,int b,int rounding)201 static WEBP_INLINE int VP8RGBToV(int r, int g, int b, int rounding) {
202 const int v = +28800 * r - 24116 * g - 4684 * b;
203 return VP8ClipUV(v, rounding);
204 }
205
206 #ifdef __cplusplus
207 } // extern "C"
208 #endif
209
210 #endif // WEBP_DSP_YUV_H_
211