1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
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_ */
|