1/*
2 * Copyright 2019 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "include/core/SkM44.h"
9#include "src/core/SkYUVMath.h"
10
11// in SkColorMatrix order (row-major)
12// Created by running SkColorMatrix_DumpYUVMatrixTables()
13
14const float Rec709_rgb_to_yuv[] = {
15 0.182586f, 0.614231f, 0.062007f, 0.000000f, 0.062745f,
16 -0.100644f, -0.338572f, 0.439216f, 0.000000f, 0.501961f,
17 0.439216f, -0.398942f, -0.040274f, 0.000000f, 0.501961f,
18 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
19};
20const float Rec709_yuv_to_rgb[] = {
21 1.164384f, 0.000000f, 1.792741f, 0.000000f, -0.972945f,
22 1.164384f, -0.213249f, -0.532909f, 0.000000f, 0.301483f,
23 1.164384f, 2.112402f, 0.000000f, 0.000000f, -1.133402f,
24 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
25};
26const float Rec601_rgb_to_yuv[] = {
27 0.256788f, 0.504129f, 0.097906f, 0.000000f, 0.062745f,
28 -0.148223f, -0.290993f, 0.439216f, 0.000000f, 0.501961f,
29 0.439216f, -0.367788f, -0.071427f, 0.000000f, 0.501961f,
30 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
31};
32const float Rec601_yuv_to_rgb[] = {
33 1.164384f, 0.000000f, 1.596027f, 0.000000f, -0.874202f,
34 1.164384f, -0.391762f, -0.812968f, 0.000000f, 0.531668f,
35 1.164384f, 2.017232f, 0.000000f, 0.000000f, -1.085631f,
36 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
37};
38const float JPEG_rgb_to_yuv[] = {
39 0.299000f, 0.587000f, 0.114000f, 0.000000f, 0.000000f,
40 -0.168736f, -0.331264f, 0.500000f, 0.000000f, 0.501961f,
41 0.500000f, -0.418688f, -0.081312f, 0.000000f, 0.501961f,
42 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
43};
44const float JPEG_yuv_to_rgb[] = {
45 1.000000f, 0.000000f, 1.402000f, 0.000000f, -0.703749f,
46 1.000000f, -0.344136f, -0.714136f, 0.000000f, 0.531211f,
47 1.000000f, 1.772000f, 0.000000f, 0.000000f, -0.889475f,
48 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
49};
50const float BT2020_rgb_to_yuv[] = {
51 0.225613f, 0.582282f, 0.050928f, 0.000000f, 0.062745f,
52 -0.122655f, -0.316560f, 0.439216f, 0.000000f, 0.501961f,
53 0.439216f, -0.403890f, -0.035326f, 0.000000f, 0.501961f,
54 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
55};
56const float BT2020_yuv_to_rgb[] = {
57 1.164384f, 0.000000f, 1.678674f, 0.000000f, -0.915688f,
58 1.164384f, -0.187326f, -0.650424f, 0.000000f, 0.347458f,
59 1.164384f, 2.141772f, 0.000000f, 0.000000f, -1.148145f,
60 0.000000f, 0.000000f, 0.000000f, 1.000000f, 0.000000f,
61};
62
63static_assert(kJPEG_SkYUVColorSpace == 0, "");
64static_assert(kRec601_SkYUVColorSpace == 1, "");
65static_assert(kRec709_SkYUVColorSpace == 2, "");
66static_assert(kBT2020_SkYUVColorSpace == 3, "");
67
68const float* yuv_to_rgb_array[] = {
69 JPEG_yuv_to_rgb,
70 Rec601_yuv_to_rgb,
71 Rec709_yuv_to_rgb,
72 BT2020_yuv_to_rgb,
73};
74
75const float* rgb_to_yuv_array[] = {
76 JPEG_rgb_to_yuv,
77 Rec601_rgb_to_yuv,
78 Rec709_rgb_to_yuv,
79 BT2020_rgb_to_yuv,
80};
81
82constexpr size_t kSizeOfColorMatrix = 20 * sizeof(float);
83
84void SkColorMatrix_RGB2YUV(SkYUVColorSpace cs, float m[20]) {
85 if ((unsigned)cs < (unsigned)kIdentity_SkYUVColorSpace) {
86 memcpy(m, rgb_to_yuv_array[(unsigned)cs], kSizeOfColorMatrix);
87 } else {
88 memset(m, 0, kSizeOfColorMatrix);
89 m[0] = m[6] = m[12] = m[18] = 1;
90 }
91}
92
93void SkColorMatrix_YUV2RGB(SkYUVColorSpace cs, float m[20]) {
94 if ((unsigned)cs < (unsigned)kIdentity_SkYUVColorSpace) {
95 memcpy(m, yuv_to_rgb_array[(unsigned)cs], kSizeOfColorMatrix);
96 } else {
97 memset(m, 0, kSizeOfColorMatrix);
98 m[0] = m[6] = m[12] = m[18] = 1;
99 }
100}
101
102///////////////////////////////////////////////////////////////////////////////////////////////////
103
104// we just drop the alpha rol/col from the colormatrix
105// output is | tr |
106// | 3x3 tg |
107// | tb |
108// | 0 0 0 1 |
109static void colormatrix_to_matrix44(const float src[20], SkM44* dst) {
110 *dst = SkM44(src[ 0], src[ 1], src[ 2], src[ 4],
111 src[ 5], src[ 6], src[ 7], src[ 9],
112 src[10], src[11], src[12], src[14],
113 0, 0, 0, 1);
114}
115
116// input: ignore the bottom row
117// output: inject identity row/column for alpha
118static void matrix44_to_colormatrix(const SkM44& src, float dst[20]) {
119 dst[0] = src.rc(0,0);
120 dst[1] = src.rc(0,1);
121 dst[2] = src.rc(0,2);
122 dst[3] = 0;
123 dst[4] = src.rc(0,3); // tx
124
125 dst[5] = src.rc(1,0);
126 dst[6] = src.rc(1,1);
127 dst[7] = src.rc(1,2);
128 dst[8] = 0;
129 dst[9] = src.rc(1,3); // ty
130
131 dst[10] = src.rc(2,0);
132 dst[11] = src.rc(2,1);
133 dst[12] = src.rc(2,2);
134 dst[13] = 0;
135 dst[14] = src.rc(2,3); // tz
136
137 dst[15] = dst[16] = dst[17] = dst[19] = 0;
138 dst[18] = 1;
139}
140
141static void scale3(float m[], float s) {
142 for (int i = 0; i < 3; ++i) {
143 m[i] *= s;
144 }
145}
146
147namespace {
148struct YUVCoeff {
149 float Kr, Kb;
150 float scaleY, addY;
151 float scaleUV;
152};
153} // namespace
154
155const YUVCoeff gCoeff[] = {
156 // kJPEG_SkYUVColorSpace
157 { 0.299f, 0.114f, 1, 0, 1, },
158
159 // kRec601_SkYUVColorSpace
160 { 0.299f, 0.114f, 219/255.f, 16/255.f, 224/255.f, },
161
162 // kRec709_SkYUVColorSpace
163 { 0.2126f, 0.0722f, 219/255.f, 16/255.f, 224/255.f, },
164
165 // kBT2020_SkYUVColorSpace
166 { 0.2627f, 0.0593f, 219/255.f, 16/255.f, 224/255.f, },
167};
168
169static void make_rgb_to_yuv_matrix(float mx[20], const YUVCoeff& c) {
170 const float Kr = c.Kr;
171 const float Kb = c.Kb;
172 const float Kg = 1.0f - Kr - Kb;
173 const float Cr = 0.5f / (1.0f - Kb);
174 const float Cb = 0.5f / (1.0f - Kr);
175
176 float m[20] = {
177 Kr, Kg, Kb, 0, c.addY,
178 -Kr, -Kg, 1-Kb, 0, 128/255.f,
179 1-Kr, -Kg, -Kb, 0, 128/255.f,
180 0, 0, 0, 1, 0,
181 };
182 memcpy(mx, m, sizeof(m));
183 scale3(mx + 0, c.scaleY);
184 scale3(mx + 5, Cr * c.scaleUV);
185 scale3(mx + 10, Cb * c.scaleUV);
186}
187
188static void dump(const float m[20], SkYUVColorSpace cs, bool rgb2yuv) {
189 const char* names[] = {
190 "JPEG", "Rec601", "Rec709", "BT2020",
191 };
192 const char* dirnames[] = {
193 "yuv_to_rgb", "rgb_to_yuv",
194 };
195 SkDebugf("const float %s_%s[] = {\n", names[cs], dirnames[rgb2yuv]);
196 for (int i = 0; i < 4; ++i) {
197 SkDebugf(" ");
198 for (int j = 0; j < 5; ++j) {
199 SkDebugf(" %9.6ff,", m[i * 5 + j]);
200 }
201 SkDebugf("\n");
202 }
203 SkDebugf("};\n");
204}
205
206// Used to create the prebuilt tables for each colorspace.
207// Don't remove this function, in case we want to recompute those tables in the future.
208void SkColorMatrix_DumpYUVMatrixTables() {
209 for (auto cs : {kRec709_SkYUVColorSpace, kRec601_SkYUVColorSpace, kJPEG_SkYUVColorSpace,
210 kBT2020_SkYUVColorSpace}) {
211 float m[20];
212 make_rgb_to_yuv_matrix(m, gCoeff[(unsigned)cs]);
213 dump(m, cs, true);
214 SkM44 m44, im44;
215 colormatrix_to_matrix44(m, &m44);
216 float im[20];
217#ifdef SK_DEBUG
218 // be sure our coversion between matrix44 and colormatrix is perfect
219 matrix44_to_colormatrix(m44, im);
220 SkASSERT(memcmp(m, im, sizeof(im)) == 0);
221#endif
222 SkAssertResult(m44.invert(&im44));
223 matrix44_to_colormatrix(im44, im);
224 dump(im, cs, false);
225 }
226}
227