1 /*
2 * Copyright 2016 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/SkICC.h"
9 #include "include/private/SkFixed.h"
10 #include "src/core/SkAutoMalloc.h"
11 #include "src/core/SkColorSpacePriv.h"
12 #include "src/core/SkEndian.h"
13 #include "src/core/SkICCPriv.h"
14 #include "src/core/SkMD5.h"
15 #include "src/core/SkUtils.h"
16
17 static constexpr char kDescriptionTagBodyPrefix[12] =
18 { 'G', 'o', 'o', 'g', 'l', 'e', '/', 'S', 'k', 'i', 'a' , '/'};
19
20 static constexpr size_t kICCDescriptionTagSize = 44;
21
22 static_assert(kICCDescriptionTagSize ==
23 sizeof(kDescriptionTagBodyPrefix) + 2 * sizeof(SkMD5::Digest), "");
24 static constexpr size_t kDescriptionTagBodySize = kICCDescriptionTagSize * 2; // ascii->utf16be
25
26 static_assert(SkIsAlign4(kDescriptionTagBodySize), "Description must be aligned to 4-bytes.");
27 static constexpr uint32_t kDescriptionTagHeader[7] {
28 SkEndian_SwapBE32(kTAG_TextType), // Type signature
29 0, // Reserved
30 SkEndian_SwapBE32(1), // Number of records
31 SkEndian_SwapBE32(12), // Record size (must be 12)
32 SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA
33 SkEndian_SwapBE32(kDescriptionTagBodySize), // Length of string
34 SkEndian_SwapBE32(28), // Offset of string
35 };
36
37 static constexpr uint32_t kWhitePointTag[5] {
38 SkEndian_SwapBE32(kXYZ_PCSSpace),
39 0,
40 SkEndian_SwapBE32(0x0000f6d6), // X = 0.96420 (D50)
41 SkEndian_SwapBE32(0x00010000), // Y = 1.00000 (D50)
42 SkEndian_SwapBE32(0x0000d32d), // Z = 0.82491 (D50)
43 };
44
45 // Google Inc. 2016 (UTF-16)
46 static constexpr uint8_t kCopyrightTagBody[] = {
47 0x00, 0x47, 0x00, 0x6f,
48 0x00, 0x6f, 0x00, 0x67,
49 0x00, 0x6c, 0x00, 0x65,
50 0x00, 0x20, 0x00, 0x49,
51 0x00, 0x6e, 0x00, 0x63,
52 0x00, 0x2e, 0x00, 0x20,
53 0x00, 0x32, 0x00, 0x30,
54 0x00, 0x31, 0x00, 0x36,
55 };
56 static_assert(SkIsAlign4(sizeof(kCopyrightTagBody)), "Copyright must be aligned to 4-bytes.");
57 static constexpr uint32_t kCopyrightTagHeader[7] {
58 SkEndian_SwapBE32(kTAG_TextType), // Type signature
59 0, // Reserved
60 SkEndian_SwapBE32(1), // Number of records
61 SkEndian_SwapBE32(12), // Record size (must be 12)
62 SkEndian_SwapBE32(SkSetFourByteTag('e', 'n', 'U', 'S')), // English USA
63 SkEndian_SwapBE32(sizeof(kCopyrightTagBody)), // Length of string
64 SkEndian_SwapBE32(28), // Offset of string
65 };
66
67 // We will write a profile with the minimum nine required tags.
68 static constexpr uint32_t kICCNumEntries = 9;
69
70 static constexpr uint32_t kTAG_desc = SkSetFourByteTag('d', 'e', 's', 'c');
71 static constexpr uint32_t kTAG_desc_Bytes = sizeof(kDescriptionTagHeader) +
72 kDescriptionTagBodySize;
73 static constexpr uint32_t kTAG_desc_Offset = kICCHeaderSize +
74 kICCNumEntries * kICCTagTableEntrySize;
75
76 static constexpr uint32_t kTAG_XYZ_Bytes = 20;
77 static constexpr uint32_t kTAG_rXYZ_Offset = kTAG_desc_Offset + kTAG_desc_Bytes;
78 static constexpr uint32_t kTAG_gXYZ_Offset = kTAG_rXYZ_Offset + kTAG_XYZ_Bytes;
79 static constexpr uint32_t kTAG_bXYZ_Offset = kTAG_gXYZ_Offset + kTAG_XYZ_Bytes;
80
81 static constexpr uint32_t kTAG_TRC_Bytes = 40;
82 static constexpr uint32_t kTAG_rTRC_Offset = kTAG_bXYZ_Offset + kTAG_XYZ_Bytes;
83 static constexpr uint32_t kTAG_gTRC_Offset = kTAG_rTRC_Offset;
84 static constexpr uint32_t kTAG_bTRC_Offset = kTAG_rTRC_Offset;
85
86 static constexpr uint32_t kTAG_wtpt = SkSetFourByteTag('w', 't', 'p', 't');
87 static constexpr uint32_t kTAG_wtpt_Offset = kTAG_bTRC_Offset + kTAG_TRC_Bytes;
88
89 static constexpr uint32_t kTAG_cprt = SkSetFourByteTag('c', 'p', 'r', 't');
90 static constexpr uint32_t kTAG_cprt_Bytes = sizeof(kCopyrightTagHeader) +
91 sizeof(kCopyrightTagBody);
92 static constexpr uint32_t kTAG_cprt_Offset = kTAG_wtpt_Offset + kTAG_XYZ_Bytes;
93
94 static constexpr uint32_t kICCProfileSize = kTAG_cprt_Offset + kTAG_cprt_Bytes;
95
96 static constexpr uint32_t kICCHeader[kICCHeaderSize / 4] {
97 SkEndian_SwapBE32(kICCProfileSize), // Size of the profile
98 0, // Preferred CMM type (ignored)
99 SkEndian_SwapBE32(0x02100000), // Version 2.1
100 SkEndian_SwapBE32(kDisplay_Profile), // Display device profile
101 SkEndian_SwapBE32(kRGB_ColorSpace), // RGB input color space
102 SkEndian_SwapBE32(kXYZ_PCSSpace), // XYZ profile connection space
103 0, 0, 0, // Date and time (ignored)
104 SkEndian_SwapBE32(kACSP_Signature), // Profile signature
105 0, // Platform target (ignored)
106 0x00000000, // Flags: not embedded, can be used independently
107 0, // Device manufacturer (ignored)
108 0, // Device model (ignored)
109 0, 0, // Device attributes (ignored)
110 SkEndian_SwapBE32(1), // Relative colorimetric rendering intent
111 SkEndian_SwapBE32(0x0000f6d6), // D50 standard illuminant (X)
112 SkEndian_SwapBE32(0x00010000), // D50 standard illuminant (Y)
113 SkEndian_SwapBE32(0x0000d32d), // D50 standard illuminant (Z)
114 0, // Profile creator (ignored)
115 0, 0, 0, 0, // Profile id checksum (ignored)
116 0, 0, 0, 0, 0, 0, 0, // Reserved (ignored)
117 SkEndian_SwapBE32(kICCNumEntries), // Number of tags
118 };
119
120 static constexpr uint32_t kICCTagTable[3 * kICCNumEntries] {
121 // Profile description
122 SkEndian_SwapBE32(kTAG_desc),
123 SkEndian_SwapBE32(kTAG_desc_Offset),
124 SkEndian_SwapBE32(kTAG_desc_Bytes),
125
126 // rXYZ
127 SkEndian_SwapBE32(kTAG_rXYZ),
128 SkEndian_SwapBE32(kTAG_rXYZ_Offset),
129 SkEndian_SwapBE32(kTAG_XYZ_Bytes),
130
131 // gXYZ
132 SkEndian_SwapBE32(kTAG_gXYZ),
133 SkEndian_SwapBE32(kTAG_gXYZ_Offset),
134 SkEndian_SwapBE32(kTAG_XYZ_Bytes),
135
136 // bXYZ
137 SkEndian_SwapBE32(kTAG_bXYZ),
138 SkEndian_SwapBE32(kTAG_bXYZ_Offset),
139 SkEndian_SwapBE32(kTAG_XYZ_Bytes),
140
141 // rTRC
142 SkEndian_SwapBE32(kTAG_rTRC),
143 SkEndian_SwapBE32(kTAG_rTRC_Offset),
144 SkEndian_SwapBE32(kTAG_TRC_Bytes),
145
146 // gTRC
147 SkEndian_SwapBE32(kTAG_gTRC),
148 SkEndian_SwapBE32(kTAG_gTRC_Offset),
149 SkEndian_SwapBE32(kTAG_TRC_Bytes),
150
151 // bTRC
152 SkEndian_SwapBE32(kTAG_bTRC),
153 SkEndian_SwapBE32(kTAG_bTRC_Offset),
154 SkEndian_SwapBE32(kTAG_TRC_Bytes),
155
156 // White point
157 SkEndian_SwapBE32(kTAG_wtpt),
158 SkEndian_SwapBE32(kTAG_wtpt_Offset),
159 SkEndian_SwapBE32(kTAG_XYZ_Bytes),
160
161 // Copyright
162 SkEndian_SwapBE32(kTAG_cprt),
163 SkEndian_SwapBE32(kTAG_cprt_Offset),
164 SkEndian_SwapBE32(kTAG_cprt_Bytes),
165 };
166
167 // This is like SkFloatToFixed, but rounds to nearest, preserving as much accuracy as possible
168 // when going float -> fixed -> float (it has the same accuracy when going fixed -> float -> fixed).
169 // The use of double is necessary to accomodate the full potential 32-bit mantissa of the 16.16
170 // SkFixed value, and so avoiding rounding problems with float. Also, see the comment in SkFixed.h.
float_round_to_fixed(float x)171 static SkFixed float_round_to_fixed(float x) {
172 return sk_float_saturate2int((float)floor((double)x * SK_Fixed1 + 0.5));
173 }
174
write_xyz_tag(uint32_t * ptr,const skcms_Matrix3x3 & toXYZD50,int col)175 static void write_xyz_tag(uint32_t* ptr, const skcms_Matrix3x3& toXYZD50, int col) {
176 ptr[0] = SkEndian_SwapBE32(kXYZ_PCSSpace);
177 ptr[1] = 0;
178 ptr[2] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[0][col]));
179 ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[1][col]));
180 ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(toXYZD50.vals[2][col]));
181 }
182
write_trc_tag(uint32_t * ptr,const skcms_TransferFunction & fn)183 static void write_trc_tag(uint32_t* ptr, const skcms_TransferFunction& fn) {
184 ptr[0] = SkEndian_SwapBE32(kTAG_ParaCurveType);
185 ptr[1] = 0;
186 ptr[2] = (uint32_t) (SkEndian_SwapBE16(kGABCDEF_ParaCurveType));
187 ptr[3] = SkEndian_SwapBE32(float_round_to_fixed(fn.g));
188 ptr[4] = SkEndian_SwapBE32(float_round_to_fixed(fn.a));
189 ptr[5] = SkEndian_SwapBE32(float_round_to_fixed(fn.b));
190 ptr[6] = SkEndian_SwapBE32(float_round_to_fixed(fn.c));
191 ptr[7] = SkEndian_SwapBE32(float_round_to_fixed(fn.d));
192 ptr[8] = SkEndian_SwapBE32(float_round_to_fixed(fn.e));
193 ptr[9] = SkEndian_SwapBE32(float_round_to_fixed(fn.f));
194 }
195
nearly_equal(float x,float y)196 static bool nearly_equal(float x, float y) {
197 // A note on why I chose this tolerance: transfer_fn_almost_equal() uses a
198 // tolerance of 0.001f, which doesn't seem to be enough to distinguish
199 // between similar transfer functions, for example: gamma2.2 and sRGB.
200 //
201 // If the tolerance is 0.0f, then this we can't distinguish between two
202 // different encodings of what is clearly the same colorspace. Some
203 // experimentation with example files lead to this number:
204 static constexpr float kTolerance = 1.0f / (1 << 11);
205 return ::fabsf(x - y) <= kTolerance;
206 }
207
nearly_equal(const skcms_TransferFunction & u,const skcms_TransferFunction & v)208 static bool nearly_equal(const skcms_TransferFunction& u,
209 const skcms_TransferFunction& v) {
210 return nearly_equal(u.g, v.g)
211 && nearly_equal(u.a, v.a)
212 && nearly_equal(u.b, v.b)
213 && nearly_equal(u.c, v.c)
214 && nearly_equal(u.d, v.d)
215 && nearly_equal(u.e, v.e)
216 && nearly_equal(u.f, v.f);
217 }
218
nearly_equal(const skcms_Matrix3x3 & u,const skcms_Matrix3x3 & v)219 static bool nearly_equal(const skcms_Matrix3x3& u, const skcms_Matrix3x3& v) {
220 for (int r = 0; r < 3; r++) {
221 for (int c = 0; c < 3; c++) {
222 if (!nearly_equal(u.vals[r][c], v.vals[r][c])) {
223 return false;
224 }
225 }
226 }
227 return true;
228 }
229
230 // Return nullptr if the color profile doen't have a special name.
get_color_profile_description(const skcms_TransferFunction & fn,const skcms_Matrix3x3 & toXYZD50)231 const char* get_color_profile_description(const skcms_TransferFunction& fn,
232 const skcms_Matrix3x3& toXYZD50) {
233 bool srgb_xfer = nearly_equal(fn, SkNamedTransferFn::kSRGB);
234 bool srgb_gamut = nearly_equal(toXYZD50, SkNamedGamut::kSRGB);
235 if (srgb_xfer && srgb_gamut) {
236 return "sRGB";
237 }
238 bool line_xfer = nearly_equal(fn, SkNamedTransferFn::kLinear);
239 if (line_xfer && srgb_gamut) {
240 return "Linear Transfer with sRGB Gamut";
241 }
242 bool twoDotTwo = nearly_equal(fn, SkNamedTransferFn::k2Dot2);
243 if (twoDotTwo && srgb_gamut) {
244 return "2.2 Transfer with sRGB Gamut";
245 }
246 if (twoDotTwo && nearly_equal(toXYZD50, SkNamedGamut::kAdobeRGB)) {
247 return "AdobeRGB";
248 }
249 bool dcip3_gamut = nearly_equal(toXYZD50, SkNamedGamut::kDCIP3);
250 if (srgb_xfer || line_xfer) {
251 if (srgb_xfer && dcip3_gamut) {
252 return "sRGB Transfer with DCI-P3 Gamut";
253 }
254 if (line_xfer && dcip3_gamut) {
255 return "Linear Transfer with DCI-P3 Gamut";
256 }
257 bool rec2020 = nearly_equal(toXYZD50, SkNamedGamut::kRec2020);
258 if (srgb_xfer && rec2020) {
259 return "sRGB Transfer with Rec-BT-2020 Gamut";
260 }
261 if (line_xfer && rec2020) {
262 return "Linear Transfer with Rec-BT-2020 Gamut";
263 }
264 }
265 return nullptr;
266 }
267
get_color_profile_tag(char dst[kICCDescriptionTagSize],const skcms_TransferFunction & fn,const skcms_Matrix3x3 & toXYZD50)268 static void get_color_profile_tag(char dst[kICCDescriptionTagSize],
269 const skcms_TransferFunction& fn,
270 const skcms_Matrix3x3& toXYZD50) {
271 SkASSERT(dst);
272 if (const char* description = get_color_profile_description(fn, toXYZD50)) {
273 SkASSERT(strlen(description) < kICCDescriptionTagSize);
274 strncpy(dst, description, kICCDescriptionTagSize);
275 // "If the length of src is less than n, strncpy() writes additional
276 // null bytes to dest to ensure that a total of n bytes are written."
277 } else {
278 strncpy(dst, kDescriptionTagBodyPrefix, sizeof(kDescriptionTagBodyPrefix));
279 SkMD5 md5;
280 md5.write(&toXYZD50, sizeof(toXYZD50));
281 static_assert(sizeof(fn) == sizeof(float) * 7, "packed");
282 md5.write(&fn, sizeof(fn));
283 SkMD5::Digest digest = md5.finish();
284 char* ptr = dst + sizeof(kDescriptionTagBodyPrefix);
285 for (unsigned i = 0; i < sizeof(SkMD5::Digest); ++i) {
286 uint8_t byte = digest.data[i];
287 *ptr++ = SkHexadecimalDigits::gUpper[byte >> 4];
288 *ptr++ = SkHexadecimalDigits::gUpper[byte & 0xF];
289 }
290 SkASSERT(ptr == dst + kICCDescriptionTagSize);
291 }
292 }
293
SkWriteICCProfile(const skcms_TransferFunction & fn,const skcms_Matrix3x3 & toXYZD50)294 sk_sp<SkData> SkWriteICCProfile(const skcms_TransferFunction& fn,
295 const skcms_Matrix3x3& toXYZD50) {
296 // We can't encode HDR transfer functions in ICC
297 if (classify_transfer_fn(fn) != sRGBish_TF) {
298 return nullptr;
299 }
300
301 SkAutoMalloc profile(kICCProfileSize);
302 uint8_t* ptr = (uint8_t*) profile.get();
303
304 // Write profile header
305 memcpy(ptr, kICCHeader, sizeof(kICCHeader));
306 ptr += sizeof(kICCHeader);
307
308 // Write tag table
309 memcpy(ptr, kICCTagTable, sizeof(kICCTagTable));
310 ptr += sizeof(kICCTagTable);
311
312 // Write profile description tag
313 memcpy(ptr, kDescriptionTagHeader, sizeof(kDescriptionTagHeader));
314 ptr += sizeof(kDescriptionTagHeader);
315 {
316 char colorProfileTag[kICCDescriptionTagSize];
317 get_color_profile_tag(colorProfileTag, fn, toXYZD50);
318
319 // ASCII --> big-endian UTF-16.
320 for (size_t i = 0; i < kICCDescriptionTagSize; i++) {
321 *ptr++ = 0;
322 *ptr++ = colorProfileTag[i];
323 }
324 }
325
326 // Write XYZ tags
327 write_xyz_tag((uint32_t*) ptr, toXYZD50, 0);
328 ptr += kTAG_XYZ_Bytes;
329 write_xyz_tag((uint32_t*) ptr, toXYZD50, 1);
330 ptr += kTAG_XYZ_Bytes;
331 write_xyz_tag((uint32_t*) ptr, toXYZD50, 2);
332 ptr += kTAG_XYZ_Bytes;
333
334 // Write TRC tag
335 write_trc_tag((uint32_t*) ptr, fn);
336 ptr += kTAG_TRC_Bytes;
337
338 // Write white point tag (must be D50)
339 memcpy(ptr, kWhitePointTag, sizeof(kWhitePointTag));
340 ptr += sizeof(kWhitePointTag);
341
342 // Write copyright tag
343 memcpy(ptr, kCopyrightTagHeader, sizeof(kCopyrightTagHeader));
344 ptr += sizeof(kCopyrightTagHeader);
345 memcpy(ptr, kCopyrightTagBody, sizeof(kCopyrightTagBody));
346 ptr += sizeof(kCopyrightTagBody);
347
348 SkASSERT(kICCProfileSize == ptr - (uint8_t*) profile.get());
349 return SkData::MakeFromMalloc(profile.release(), kICCProfileSize);
350 }
351