1 // Copyright 2019 Joe Drago. All rights reserved.
2 // SPDX-License-Identifier: BSD-2-Clause
3
4 #include "avif/internal.h"
5
6 #include <math.h>
7 #include <string.h>
8
9 struct avifColorPrimariesTable
10 {
11 avifColorPrimaries colorPrimariesEnum;
12 const char * name;
13 float primaries[8]; // rX, rY, gX, gY, bX, bY, wX, wY
14 };
15 static const struct avifColorPrimariesTable avifColorPrimariesTables[] = {
16 { AVIF_COLOR_PRIMARIES_BT709, "BT.709", { 0.64f, 0.33f, 0.3f, 0.6f, 0.15f, 0.06f, 0.3127f, 0.329f } },
17 { AVIF_COLOR_PRIMARIES_BT470M, "BT.470-6 System M", { 0.67f, 0.33f, 0.21f, 0.71f, 0.14f, 0.08f, 0.310f, 0.316f } },
18 { AVIF_COLOR_PRIMARIES_BT470BG, "BT.470-6 System BG", { 0.64f, 0.33f, 0.29f, 0.60f, 0.15f, 0.06f, 0.3127f, 0.3290f } },
19 { AVIF_COLOR_PRIMARIES_BT601, "BT.601", { 0.630f, 0.340f, 0.310f, 0.595f, 0.155f, 0.070f, 0.3127f, 0.3290f } },
20 { AVIF_COLOR_PRIMARIES_SMPTE240, "SMPTE 240M", { 0.630f, 0.340f, 0.310f, 0.595f, 0.155f, 0.070f, 0.3127f, 0.3290f } },
21 { AVIF_COLOR_PRIMARIES_GENERIC_FILM, "Generic film", { 0.681f, 0.319f, 0.243f, 0.692f, 0.145f, 0.049f, 0.310f, 0.316f } },
22 { AVIF_COLOR_PRIMARIES_BT2020, "BT.2020", { 0.708f, 0.292f, 0.170f, 0.797f, 0.131f, 0.046f, 0.3127f, 0.3290f } },
23 { AVIF_COLOR_PRIMARIES_XYZ, "XYZ", { 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.3333f, 0.3333f } },
24 { AVIF_COLOR_PRIMARIES_SMPTE431, "SMPTE RP 431-2", { 0.680f, 0.320f, 0.265f, 0.690f, 0.150f, 0.060f, 0.314f, 0.351f } },
25 { AVIF_COLOR_PRIMARIES_SMPTE432, "SMPTE EG 432-1 (DCI P3)", { 0.680f, 0.320f, 0.265f, 0.690f, 0.150f, 0.060f, 0.3127f, 0.3290f } },
26 { AVIF_COLOR_PRIMARIES_EBU3213, "EBU Tech. 3213-E", { 0.630f, 0.340f, 0.295f, 0.605f, 0.155f, 0.077f, 0.3127f, 0.3290f } }
27 };
28 static const int avifColorPrimariesTableSize = sizeof(avifColorPrimariesTables) / sizeof(avifColorPrimariesTables[0]);
29
avifColorPrimariesGetValues(avifColorPrimaries acp,float outPrimaries[8])30 void avifColorPrimariesGetValues(avifColorPrimaries acp, float outPrimaries[8])
31 {
32 for (int i = 0; i < avifColorPrimariesTableSize; ++i) {
33 if (avifColorPrimariesTables[i].colorPrimariesEnum == acp) {
34 memcpy(outPrimaries, avifColorPrimariesTables[i].primaries, sizeof(avifColorPrimariesTables[i].primaries));
35 return;
36 }
37 }
38
39 // if we get here, the color primaries are unknown. Just return a reasonable default.
40 memcpy(outPrimaries, avifColorPrimariesTables[0].primaries, sizeof(avifColorPrimariesTables[0].primaries));
41 }
42
matchesTo3RoundedPlaces(float a,float b)43 static avifBool matchesTo3RoundedPlaces(float a, float b)
44 {
45 return (fabsf(a - b) < 0.001f);
46 }
47
primariesMatch(const float p1[8],const float p2[8])48 static avifBool primariesMatch(const float p1[8], const float p2[8])
49 {
50 return matchesTo3RoundedPlaces(p1[0], p2[0]) && matchesTo3RoundedPlaces(p1[1], p2[1]) &&
51 matchesTo3RoundedPlaces(p1[2], p2[2]) && matchesTo3RoundedPlaces(p1[3], p2[3]) && matchesTo3RoundedPlaces(p1[4], p2[4]) &&
52 matchesTo3RoundedPlaces(p1[5], p2[5]) && matchesTo3RoundedPlaces(p1[6], p2[6]) && matchesTo3RoundedPlaces(p1[7], p2[7]);
53 }
54
avifColorPrimariesFind(const float inPrimaries[8],const char ** outName)55 avifColorPrimaries avifColorPrimariesFind(const float inPrimaries[8], const char ** outName)
56 {
57 if (outName) {
58 *outName = NULL;
59 }
60
61 for (int i = 0; i < avifColorPrimariesTableSize; ++i) {
62 if (primariesMatch(inPrimaries, avifColorPrimariesTables[i].primaries)) {
63 if (outName) {
64 *outName = avifColorPrimariesTables[i].name;
65 }
66 return avifColorPrimariesTables[i].colorPrimariesEnum;
67 }
68 }
69 return AVIF_COLOR_PRIMARIES_UNKNOWN;
70 }
71
72 struct avifMatrixCoefficientsTable
73 {
74 avifMatrixCoefficients matrixCoefficientsEnum;
75 const char * name;
76 const float kr;
77 const float kb;
78 };
79
80 // https://www.itu.int/rec/T-REC-H.273-201612-I/en
81 static const struct avifMatrixCoefficientsTable matrixCoefficientsTables[] = {
82 //{ AVIF_MATRIX_COEFFICIENTS_IDENTITY, "Identity", 0.0f, 0.0f, }, // Handled elsewhere
83 { AVIF_MATRIX_COEFFICIENTS_BT709, "BT.709", 0.2126f, 0.0722f },
84 { AVIF_MATRIX_COEFFICIENTS_FCC, "FCC USFC 73.682", 0.30f, 0.11f },
85 { AVIF_MATRIX_COEFFICIENTS_BT470BG, "BT.470-6 System BG", 0.299f, 0.114f },
86 { AVIF_MATRIX_COEFFICIENTS_BT601, "BT.601", 0.299f, 0.114f },
87 { AVIF_MATRIX_COEFFICIENTS_SMPTE240, "SMPTE ST 240", 0.212f, 0.087f },
88 { AVIF_MATRIX_COEFFICIENTS_BT2020_NCL, "BT.2020 (non-constant luminance)", 0.2627f, 0.0593f },
89 //{ AVIF_MATRIX_COEFFICIENTS_BT2020_CL, "BT.2020 (constant luminance)", 0.2627f, 0.0593f }, // FIXME: It is not an linear transformation.
90 //{ AVIF_MATRIX_COEFFICIENTS_SMPTE2085, "ST 2085", 0.0f, 0.0f }, // FIXME: ST2085 can't represent using Kr and Kb.
91 //{ AVIF_MATRIX_COEFFICIENTS_CHROMA_DERIVED_CL, "Chromaticity-derived constant luminance system", 0.0f, 0.0f } // FIXME: It is not an linear transformation.
92 //{ AVIF_MATRIX_COEFFICIENTS_ICTCP, "BT.2100-0 ICtCp", 0.0f, 0.0f }, // FIXME: This can't represent using Kr and Kb.
93 };
94
95 static const int avifMatrixCoefficientsTableSize = sizeof(matrixCoefficientsTables) / sizeof(matrixCoefficientsTables[0]);
96
calcYUVInfoFromCICP(const avifImage * image,float coeffs[3])97 static avifBool calcYUVInfoFromCICP(const avifImage * image, float coeffs[3])
98 {
99 if (image->matrixCoefficients == AVIF_MATRIX_COEFFICIENTS_CHROMA_DERIVED_NCL) {
100 float primaries[8];
101 avifColorPrimariesGetValues(image->colorPrimaries, primaries);
102 float const rX = primaries[0];
103 float const rY = primaries[1];
104 float const gX = primaries[2];
105 float const gY = primaries[3];
106 float const bX = primaries[4];
107 float const bY = primaries[5];
108 float const wX = primaries[6];
109 float const wY = primaries[7];
110 float const rZ = 1.0f - (rX + rY); // (Eq. 34)
111 float const gZ = 1.0f - (gX + gY); // (Eq. 35)
112 float const bZ = 1.0f - (bX + bY); // (Eq. 36)
113 float const wZ = 1.0f - (wX + wY); // (Eq. 37)
114 float const kr = (rY * (wX * (gY * bZ - bY * gZ) + wY * (bX * gZ - gX * bZ) + wZ * (gX * bY - bX * gY))) /
115 (wY * (rX * (gY * bZ - bY * gZ) + gX * (bY * rZ - rY * bZ) + bX * (rY * gZ - gY * rZ)));
116 // (Eq. 32)
117 float const kb = (bY * (wX * (rY * gZ - gY * rZ) + wY * (gX * rZ - rX * gZ) + wZ * (rX * gY - gX * rY))) /
118 (wY * (rX * (gY * bZ - bY * gZ) + gX * (bY * rZ - rY * bZ) + bX * (rY * gZ - gY * rZ)));
119 // (Eq. 33)
120 coeffs[0] = kr;
121 coeffs[2] = kb;
122 coeffs[1] = 1.0f - coeffs[0] - coeffs[2];
123 return AVIF_TRUE;
124 } else {
125 for (int i = 0; i < avifMatrixCoefficientsTableSize; ++i) {
126 const struct avifMatrixCoefficientsTable * const table = &matrixCoefficientsTables[i];
127 if (table->matrixCoefficientsEnum == image->matrixCoefficients) {
128 coeffs[0] = table->kr;
129 coeffs[2] = table->kb;
130 coeffs[1] = 1.0f - coeffs[0] - coeffs[2];
131 return AVIF_TRUE;
132 }
133 }
134 }
135 return AVIF_FALSE;
136 }
137
avifCalcYUVCoefficients(const avifImage * image,float * outR,float * outG,float * outB)138 void avifCalcYUVCoefficients(const avifImage * image, float * outR, float * outG, float * outB)
139 {
140 // (As of ISO/IEC 23000-22:2019 Amendment 2)
141 // MIAF Section 7.3.6.4 "Colour information property":
142 //
143 // If a coded image has no associated colour property, the default property is defined as having
144 // colour_type equal to 'nclx' with properties as follows:
145 // – colour_primaries equal to 1,
146 // – transfer_characteristics equal to 13,
147 // – matrix_coefficients equal to 5 or 6 (which are functionally identical), and
148 // – full_range_flag equal to 1.
149 // Only if the colour information property of the image matches these default values, the colour
150 // property may be omitted; all other images shall have an explicitly declared colour space via
151 // association with a property of this type.
152 //
153 // See here for the discussion: https://github.com/AOMediaCodec/av1-avif/issues/77#issuecomment-676526097
154
155 // matrix_coefficients of [5,6] == BT.601:
156 float kr = 0.299f;
157 float kb = 0.114f;
158 float kg = 1.0f - kr - kb;
159
160 float coeffs[3];
161 if (calcYUVInfoFromCICP(image, coeffs)) {
162 kr = coeffs[0];
163 kg = coeffs[1];
164 kb = coeffs[2];
165 }
166
167 *outR = kr;
168 *outG = kg;
169 *outB = kb;
170 }
171