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 | |
59 | static WEBP_INLINE int MultHi(int v, int coeff) { // _mm_mulhi_epu16 emulation |
60 | return (v * coeff) >> 8; |
61 | } |
62 | |
63 | static WEBP_INLINE int VP8Clip8(int v) { |
64 | return ((v & ~YUV_MASK2) == 0) ? (v >> YUV_FIX2) : (v < 0) ? 0 : 255; |
65 | } |
66 | |
67 | static WEBP_INLINE int VP8YUVToR(int y, int v) { |
68 | return VP8Clip8(MultHi(y, 19077) + MultHi(v, 26149) - 14234); |
69 | } |
70 | |
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 | |
75 | static WEBP_INLINE int VP8YUVToB(int y, int u) { |
76 | return VP8Clip8(MultHi(y, 19077) + MultHi(u, 33050) - 17685); |
77 | } |
78 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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: |
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 | |
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 | |
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 | |
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 | |