1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
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24
25 // This file is available under and governed by the GNU General Public
26 // License version 2 only, as published by the Free Software Foundation.
27 // However, the following notice accompanied the original version of this
28 // file:
29 //
30 //---------------------------------------------------------------------------------
31 //
32 // Little Color Management System
33 // Copyright (c) 1998-2014 Marti Maria Saguer
34 //
35 // Permission is hereby granted, free of charge, to any person obtaining
36 // a copy of this software and associated documentation files (the "Software"),
37 // to deal in the Software without restriction, including without limitation
38 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
39 // and/or sell copies of the Software, and to permit persons to whom the Software
40 // is furnished to do so, subject to the following conditions:
41 //
42 // The above copyright notice and this permission notice shall be included in
43 // all copies or substantial portions of the Software.
44 //
45 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
46 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
47 // THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
48 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
49 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
50 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
51 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
52 //
53 //---------------------------------------------------------------------------------
54 //
55
56 #include "lcms2_internal.h"
57
58
59 #define cmsmin(a, b) (((a) < (b)) ? (a) : (b))
60 #define cmsmax(a, b) (((a) > (b)) ? (a) : (b))
61
62 // This file contains routines for resampling and LUT optimization, black point detection
63 // and black preservation.
64
65 // Black point detection -------------------------------------------------------------------------
66
67
68 // PCS -> PCS round trip transform, always uses relative intent on the device -> pcs
69 static
70 cmsHTRANSFORM CreateRoundtripXForm(cmsHPROFILE hProfile, cmsUInt32Number nIntent)
71 {
72 cmsContext ContextID = cmsGetProfileContextID(hProfile);
73 cmsHPROFILE hLab = cmsCreateLab4ProfileTHR(ContextID, NULL);
74 cmsHTRANSFORM xform;
75 cmsBool BPC[4] = { FALSE, FALSE, FALSE, FALSE };
76 cmsFloat64Number States[4] = { 1.0, 1.0, 1.0, 1.0 };
77 cmsHPROFILE hProfiles[4];
78 cmsUInt32Number Intents[4];
79
80 hProfiles[0] = hLab; hProfiles[1] = hProfile; hProfiles[2] = hProfile; hProfiles[3] = hLab;
81 Intents[0] = INTENT_RELATIVE_COLORIMETRIC; Intents[1] = nIntent; Intents[2] = INTENT_RELATIVE_COLORIMETRIC; Intents[3] = INTENT_RELATIVE_COLORIMETRIC;
82
83 xform = cmsCreateExtendedTransform(ContextID, 4, hProfiles, BPC, Intents,
84 States, NULL, 0, TYPE_Lab_DBL, TYPE_Lab_DBL, cmsFLAGS_NOCACHE|cmsFLAGS_NOOPTIMIZE);
85
86 cmsCloseProfile(hLab);
87 return xform;
88 }
89
90 // Use darker colorants to obtain black point. This works in the relative colorimetric intent and
91 // assumes more ink results in darker colors. No ink limit is assumed.
92 static
93 cmsBool BlackPointAsDarkerColorant(cmsHPROFILE hInput,
94 cmsUInt32Number Intent,
95 cmsCIEXYZ* BlackPoint,
96 cmsUInt32Number dwFlags)
97 {
98 cmsUInt16Number *Black;
99 cmsHTRANSFORM xform;
100 cmsColorSpaceSignature Space;
101 cmsUInt32Number nChannels;
102 cmsUInt32Number dwFormat;
103 cmsHPROFILE hLab;
104 cmsCIELab Lab;
105 cmsCIEXYZ BlackXYZ;
106 cmsContext ContextID = cmsGetProfileContextID(hInput);
107
108 // If the profile does not support input direction, assume Black point 0
109 if (!cmsIsIntentSupported(hInput, Intent, LCMS_USED_AS_INPUT)) {
110
111 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
112 return FALSE;
113 }
114
115 // Create a formatter which has n channels and floating point
116 dwFormat = cmsFormatterForColorspaceOfProfile(hInput, 2, FALSE);
117
118 // Try to get black by using black colorant
119 Space = cmsGetColorSpace(hInput);
120
121 // This function returns darker colorant in 16 bits for several spaces
122 if (!_cmsEndPointsBySpace(Space, NULL, &Black, &nChannels)) {
123
124 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
125 return FALSE;
126 }
127
128 if (nChannels != T_CHANNELS(dwFormat)) {
129 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
130 return FALSE;
131 }
132
133 // Lab will be used as the output space, but lab2 will avoid recursion
134 hLab = cmsCreateLab2ProfileTHR(ContextID, NULL);
135 if (hLab == NULL) {
136 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
137 return FALSE;
138 }
139
140 // Create the transform
141 xform = cmsCreateTransformTHR(ContextID, hInput, dwFormat,
142 hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOOPTIMIZE|cmsFLAGS_NOCACHE);
143 cmsCloseProfile(hLab);
144
145 if (xform == NULL) {
146
147 // Something went wrong. Get rid of open resources and return zero as black
148 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
149 return FALSE;
150 }
151
152 // Convert black to Lab
153 cmsDoTransform(xform, Black, &Lab, 1);
154
155 // Force it to be neutral, clip to max. L* of 50
156 Lab.a = Lab.b = 0;
157 if (Lab.L > 50) Lab.L = 50;
158
159 // Free the resources
160 cmsDeleteTransform(xform);
161
162 // Convert from Lab (which is now clipped) to XYZ.
163 cmsLab2XYZ(NULL, &BlackXYZ, &Lab);
164
165 if (BlackPoint != NULL)
166 *BlackPoint = BlackXYZ;
167
168 cmsUNUSED_PARAMETER(dwFlags);
169
170 return TRUE;
171
172 }
173
174 // Get a black point of output CMYK profile, discounting any ink-limiting embedded
175 // in the profile. For doing that, we use perceptual intent in input direction:
176 // Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab
177 static
178 cmsBool BlackPointUsingPerceptualBlack(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile)
179 {
180 cmsHTRANSFORM hRoundTrip;
181 cmsCIELab LabIn, LabOut;
182 cmsCIEXYZ BlackXYZ;
183
184 // Is the intent supported by the profile?
185 if (!cmsIsIntentSupported(hProfile, INTENT_PERCEPTUAL, LCMS_USED_AS_INPUT)) {
186
187 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
188 return TRUE;
189 }
190
191 hRoundTrip = CreateRoundtripXForm(hProfile, INTENT_PERCEPTUAL);
192 if (hRoundTrip == NULL) {
193 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
194 return FALSE;
195 }
196
197 LabIn.L = LabIn.a = LabIn.b = 0;
198 cmsDoTransform(hRoundTrip, &LabIn, &LabOut, 1);
199
200 // Clip Lab to reasonable limits
201 if (LabOut.L > 50) LabOut.L = 50;
202 LabOut.a = LabOut.b = 0;
203
204 cmsDeleteTransform(hRoundTrip);
205
206 // Convert it to XYZ
207 cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);
208
209 if (BlackPoint != NULL)
210 *BlackPoint = BlackXYZ;
211
212 return TRUE;
213 }
214
215 // This function shouldn't exist at all -- there is such quantity of broken
216 // profiles on black point tag, that we must somehow fix chromaticity to
217 // avoid huge tint when doing Black point compensation. This function does
218 // just that. There is a special flag for using black point tag, but turned
219 // off by default because it is bogus on most profiles. The detection algorithm
220 // involves to turn BP to neutral and to use only L component.
221 cmsBool CMSEXPORT cmsDetectBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
222 {
223 cmsProfileClassSignature devClass;
224
225 // Make sure the device class is adequate
226 devClass = cmsGetDeviceClass(hProfile);
227 if (devClass == cmsSigLinkClass ||
228 devClass == cmsSigAbstractClass ||
229 devClass == cmsSigNamedColorClass) {
230 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
231 return FALSE;
232 }
233
234 // Make sure intent is adequate
235 if (Intent != INTENT_PERCEPTUAL &&
236 Intent != INTENT_RELATIVE_COLORIMETRIC &&
237 Intent != INTENT_SATURATION) {
238 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
239 return FALSE;
240 }
241
242 // v4 + perceptual & saturation intents does have its own black point, and it is
243 // well specified enough to use it. Black point tag is deprecated in V4.
244 if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
245 (Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
246
247 // Matrix shaper share MRC & perceptual intents
248 if (cmsIsMatrixShaper(hProfile))
249 return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);
250
251 // Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents
252 BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;
253 BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
254 BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
255
256 return TRUE;
257 }
258
259
260 #ifdef CMS_USE_PROFILE_BLACK_POINT_TAG
261
262 // v2, v4 rel/abs colorimetric
263 if (cmsIsTag(hProfile, cmsSigMediaBlackPointTag) &&
264 Intent == INTENT_RELATIVE_COLORIMETRIC) {
265
266 cmsCIEXYZ *BlackPtr, BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;
267 cmsCIELab Lab;
268
269 // If black point is specified, then use it,
270
271 BlackPtr = cmsReadTag(hProfile, cmsSigMediaBlackPointTag);
272 if (BlackPtr != NULL) {
273
274 BlackXYZ = *BlackPtr;
275 _cmsReadMediaWhitePoint(&MediaWhite, hProfile);
276
277 // Black point is absolute XYZ, so adapt to D50 to get PCS value
278 cmsAdaptToIlluminant(&UntrustedBlackPoint, &MediaWhite, cmsD50_XYZ(), &BlackXYZ);
279
280 // Force a=b=0 to get rid of any chroma
281 cmsXYZ2Lab(NULL, &Lab, &UntrustedBlackPoint);
282 Lab.a = Lab.b = 0;
283 if (Lab.L > 50) Lab.L = 50; // Clip to L* <= 50
284 cmsLab2XYZ(NULL, &TrustedBlackPoint, &Lab);
285
286 if (BlackPoint != NULL)
287 *BlackPoint = TrustedBlackPoint;
288
289 return TRUE;
290 }
291 }
292 #endif
293
294 // That is about v2 profiles.
295
296 // If output profile, discount ink-limiting and that's all
297 if (Intent == INTENT_RELATIVE_COLORIMETRIC &&
298 (cmsGetDeviceClass(hProfile) == cmsSigOutputClass) &&
299 (cmsGetColorSpace(hProfile) == cmsSigCmykData))
300 return BlackPointUsingPerceptualBlack(BlackPoint, hProfile);
301
302 // Nope, compute BP using current intent.
303 return BlackPointAsDarkerColorant(hProfile, Intent, BlackPoint, dwFlags);
304 }
305
306
307
308 // ---------------------------------------------------------------------------------------------------------
309
310 // Least Squares Fit of a Quadratic Curve to Data
311 // http://www.personal.psu.edu/jhm/f90/lectures/lsq2.html
312
313 static
314 cmsFloat64Number RootOfLeastSquaresFitQuadraticCurve(int n, cmsFloat64Number x[], cmsFloat64Number y[])
315 {
316 double sum_x = 0, sum_x2 = 0, sum_x3 = 0, sum_x4 = 0;
317 double sum_y = 0, sum_yx = 0, sum_yx2 = 0;
318 double d, a, b, c;
319 int i;
320 cmsMAT3 m;
321 cmsVEC3 v, res;
322
323 if (n < 4) return 0;
324
325 for (i=0; i < n; i++) {
326
327 double xn = x[i];
328 double yn = y[i];
329
330 sum_x += xn;
331 sum_x2 += xn*xn;
332 sum_x3 += xn*xn*xn;
333 sum_x4 += xn*xn*xn*xn;
334
335 sum_y += yn;
336 sum_yx += yn*xn;
337 sum_yx2 += yn*xn*xn;
338 }
339
340 _cmsVEC3init(&m.v[0], n, sum_x, sum_x2);
341 _cmsVEC3init(&m.v[1], sum_x, sum_x2, sum_x3);
342 _cmsVEC3init(&m.v[2], sum_x2, sum_x3, sum_x4);
343
344 _cmsVEC3init(&v, sum_y, sum_yx, sum_yx2);
345
346 if (!_cmsMAT3solve(&res, &m, &v)) return 0;
347
348
349 a = res.n[2];
350 b = res.n[1];
351 c = res.n[0];
352
353 if (fabs(a) < 1.0E-10) {
354
355 return cmsmin(0, cmsmax(50, -c/b ));
356 }
357 else {
358
359 d = b*b - 4.0 * a * c;
360 if (d <= 0) {
361 return 0;
362 }
363 else {
364
365 double rt = (-b + sqrt(d)) / (2.0 * a);
366
367 return cmsmax(0, cmsmin(50, rt));
368 }
369 }
370
371 }
372
373
374
375 // Calculates the black point of a destination profile.
376 // This algorithm comes from the Adobe paper disclosing its black point compensation method.
377 cmsBool CMSEXPORT cmsDetectDestinationBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
378 {
379 cmsColorSpaceSignature ColorSpace;
380 cmsHTRANSFORM hRoundTrip = NULL;
381 cmsCIELab InitialLab, destLab, Lab;
382 cmsFloat64Number inRamp[256], outRamp[256];
383 cmsFloat64Number MinL, MaxL;
384 cmsBool NearlyStraightMidrange = TRUE;
385 cmsFloat64Number yRamp[256];
386 cmsFloat64Number x[256], y[256];
387 cmsFloat64Number lo, hi;
388 int n, l;
389 cmsProfileClassSignature devClass;
390
391 // Make sure the device class is adequate
392 devClass = cmsGetDeviceClass(hProfile);
393 if (devClass == cmsSigLinkClass ||
394 devClass == cmsSigAbstractClass ||
395 devClass == cmsSigNamedColorClass) {
396 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
397 return FALSE;
398 }
399
400 // Make sure intent is adequate
401 if (Intent != INTENT_PERCEPTUAL &&
402 Intent != INTENT_RELATIVE_COLORIMETRIC &&
403 Intent != INTENT_SATURATION) {
404 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
405 return FALSE;
406 }
407
408
409 // v4 + perceptual & saturation intents does have its own black point, and it is
410 // well specified enough to use it. Black point tag is deprecated in V4.
411 if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
412 (Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
413
414 // Matrix shaper share MRC & perceptual intents
415 if (cmsIsMatrixShaper(hProfile))
416 return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);
417
418 // Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents
419 BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;
420 BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
421 BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
422 return TRUE;
423 }
424
425
426 // Check if the profile is lut based and gray, rgb or cmyk (7.2 in Adobe's document)
427 ColorSpace = cmsGetColorSpace(hProfile);
428 if (!cmsIsCLUT(hProfile, Intent, LCMS_USED_AS_OUTPUT ) ||
429 (ColorSpace != cmsSigGrayData &&
430 ColorSpace != cmsSigRgbData &&
431 ColorSpace != cmsSigCmykData)) {
432
433 // In this case, handle as input case
434 return cmsDetectBlackPoint(BlackPoint, hProfile, Intent, dwFlags);
435 }
436
437 // It is one of the valid cases!, use Adobe algorithm
438
439
440 // Set a first guess, that should work on good profiles.
441 if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
442
443 cmsCIEXYZ IniXYZ;
444
445 // calculate initial Lab as source black point
446 if (!cmsDetectBlackPoint(&IniXYZ, hProfile, Intent, dwFlags)) {
447 return FALSE;
448 }
449
450 // convert the XYZ to lab
451 cmsXYZ2Lab(NULL, &InitialLab, &IniXYZ);
452
453 } else {
454
455 // set the initial Lab to zero, that should be the black point for perceptual and saturation
456 InitialLab.L = 0;
457 InitialLab.a = 0;
458 InitialLab.b = 0;
459 }
460
461
462 // Step 2
463 // ======
464
465 // Create a roundtrip. Define a Transform BT for all x in L*a*b*
466 hRoundTrip = CreateRoundtripXForm(hProfile, Intent);
467 if (hRoundTrip == NULL) return FALSE;
468
469 // Compute ramps
470
471 for (l=0; l < 256; l++) {
472
473 Lab.L = (cmsFloat64Number) (l * 100.0) / 255.0;
474 Lab.a = cmsmin(50, cmsmax(-50, InitialLab.a));
475 Lab.b = cmsmin(50, cmsmax(-50, InitialLab.b));
476
477 cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
478
479 inRamp[l] = Lab.L;
480 outRamp[l] = destLab.L;
481 }
482
483 // Make monotonic
484 for (l = 254; l > 0; --l) {
485 outRamp[l] = cmsmin(outRamp[l], outRamp[l+1]);
486 }
487
488 // Check
489 if (! (outRamp[0] < outRamp[255])) {
490
491 cmsDeleteTransform(hRoundTrip);
492 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
493 return FALSE;
494 }
495
496
497 // Test for mid range straight (only on relative colorimetric)
498 NearlyStraightMidrange = TRUE;
499 MinL = outRamp[0]; MaxL = outRamp[255];
500 if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
501
502 for (l=0; l < 256; l++) {
503
504 if (! ((inRamp[l] <= MinL + 0.2 * (MaxL - MinL) ) ||
505 (fabs(inRamp[l] - outRamp[l]) < 4.0 )))
506 NearlyStraightMidrange = FALSE;
507 }
508
509 // If the mid range is straight (as determined above) then the
510 // DestinationBlackPoint shall be the same as initialLab.
511 // Otherwise, the DestinationBlackPoint shall be determined
512 // using curve fitting.
513 if (NearlyStraightMidrange) {
514
515 cmsLab2XYZ(NULL, BlackPoint, &InitialLab);
516 cmsDeleteTransform(hRoundTrip);
517 return TRUE;
518 }
519 }
520
521
522 // curve fitting: The round-trip curve normally looks like a nearly constant section at the black point,
523 // with a corner and a nearly straight line to the white point.
524 for (l=0; l < 256; l++) {
525
526 yRamp[l] = (outRamp[l] - MinL) / (MaxL - MinL);
527 }
528
529 // find the black point using the least squares error quadratic curve fitting
530 if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
531 lo = 0.1;
532 hi = 0.5;
533 }
534 else {
535
536 // Perceptual and saturation
537 lo = 0.03;
538 hi = 0.25;
539 }
540
541 // Capture shadow points for the fitting.
542 n = 0;
543 for (l=0; l < 256; l++) {
544
545 cmsFloat64Number ff = yRamp[l];
546
547 if (ff >= lo && ff < hi) {
548 x[n] = inRamp[l];
549 y[n] = yRamp[l];
550 n++;
551 }
552 }
553
554
555 // No suitable points
556 if (n < 3 ) {
557 cmsDeleteTransform(hRoundTrip);
558 BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
559 return FALSE;
560 }
561
562
563 // fit and get the vertex of quadratic curve
564 Lab.L = RootOfLeastSquaresFitQuadraticCurve(n, x, y);
565
566 if (Lab.L < 0.0) { // clip to zero L* if the vertex is negative
567 Lab.L = 0;
568 }
569
570 Lab.a = InitialLab.a;
571 Lab.b = InitialLab.b;
572
573 cmsLab2XYZ(NULL, BlackPoint, &Lab);
574
575 cmsDeleteTransform(hRoundTrip);
576 return TRUE;
577 }