267 lines
9.6 KiB
C
267 lines
9.6 KiB
C
//---------------------------------------------------------------------------------
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//
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// Little Color Management System
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// Copyright (c) 1998-2010 Marti Maria Saguer
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the Software
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// is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
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// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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//---------------------------------------------------------------------------------
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//
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#include "lcms2_internal.h"
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// This file contains routines for resampling and LUT optimization, black point detection
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// and black preservation.
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// Black point detection -------------------------------------------------------------------------
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// PCS -> PCS round trip transform, always uses relative intent on the device -> pcs
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static
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cmsHTRANSFORM CreateRoundtripXForm(cmsHPROFILE hProfile, cmsUInt32Number nIntent)
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{
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cmsHPROFILE hLab = cmsCreateLab4Profile(NULL);
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cmsHTRANSFORM xform;
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cmsBool BPC[4] = { FALSE, FALSE, FALSE, FALSE };
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cmsFloat64Number States[4] = { 1.0, 1.0, 1.0, 1.0 };
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cmsHPROFILE hProfiles[4];
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cmsUInt32Number Intents[4];
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cmsContext ContextID = cmsGetProfileContextID(hProfile);
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hProfiles[0] = hLab; hProfiles[1] = hProfile; hProfiles[2] = hProfile; hProfiles[3] = hLab;
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Intents[0] = INTENT_RELATIVE_COLORIMETRIC; Intents[1] = nIntent; Intents[2] = INTENT_RELATIVE_COLORIMETRIC; Intents[3] = INTENT_RELATIVE_COLORIMETRIC;
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xform = cmsCreateExtendedTransform(ContextID, 4, hProfiles, BPC, Intents,
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States, NULL, 0, TYPE_Lab_DBL, TYPE_Lab_DBL, cmsFLAGS_NOCACHE|cmsFLAGS_NOOPTIMIZE);
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cmsCloseProfile(hLab);
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return xform;
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}
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// Use darker colorants to obtain black point. This works in the relative colorimetric intent and
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// assumes more ink results in darker colors. No ink limit is assumed.
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static
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cmsBool BlackPointAsDarkerColorant(cmsHPROFILE hInput,
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cmsUInt32Number Intent,
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cmsCIEXYZ* BlackPoint,
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cmsUInt32Number dwFlags)
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{
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cmsUInt16Number *Black;
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cmsHTRANSFORM xform;
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cmsColorSpaceSignature Space;
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cmsUInt32Number nChannels;
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cmsUInt32Number dwFormat;
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cmsHPROFILE hLab;
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cmsCIELab Lab;
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cmsCIEXYZ BlackXYZ;
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cmsContext ContextID = cmsGetProfileContextID(hInput);
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// If the profile does not support input direction, assume Black point 0
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if (!cmsIsIntentSupported(hInput, Intent, LCMS_USED_AS_INPUT)) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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// Create a formatter which has n channels and floating point
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dwFormat = cmsFormatterForColorspaceOfProfile(hInput, 2, FALSE);
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// Try to get black by using black colorant
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Space = cmsGetColorSpace(hInput);
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// This function returns darker colorant in 16 bits for several spaces
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if (!_cmsEndPointsBySpace(Space, NULL, &Black, &nChannels)) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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if (nChannels != T_CHANNELS(dwFormat)) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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// Lab will be used as the output space, but lab2 will avoid recursion
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hLab = cmsCreateLab2ProfileTHR(ContextID, NULL);
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if (hLab == NULL) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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// Create the transform
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xform = cmsCreateTransformTHR(ContextID, hInput, dwFormat,
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hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOOPTIMIZE|cmsFLAGS_NOCACHE);
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cmsCloseProfile(hLab);
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if (xform == NULL) {
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// Something went wrong. Get rid of open resources and return zero as black
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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// Convert black to Lab
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cmsDoTransform(xform, Black, &Lab, 1);
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// Force it to be neutral, clip to max. L* of 50
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Lab.a = Lab.b = 0;
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if (Lab.L > 50) Lab.L = 50;
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// Free the resources
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cmsDeleteTransform(xform);
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// Convert from Lab (which is now clipped) to XYZ.
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cmsLab2XYZ(NULL, &BlackXYZ, &Lab);
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if (BlackPoint != NULL)
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*BlackPoint = BlackXYZ;
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return TRUE;
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cmsUNUSED_PARAMETER(dwFlags);
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}
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// Get a black point of output CMYK profile, discounting any ink-limiting embedded
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// in the profile. For doing that, we use perceptual intent in input direction:
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// Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab
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static
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cmsBool BlackPointUsingPerceptualBlack(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile)
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{
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cmsHTRANSFORM hRoundTrip;
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cmsCIELab LabIn, LabOut;
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cmsCIEXYZ BlackXYZ;
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// Is the intent supported by the profile?
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if (!cmsIsIntentSupported(hProfile, INTENT_PERCEPTUAL, LCMS_USED_AS_INPUT)) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return TRUE;
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}
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hRoundTrip = CreateRoundtripXForm(hProfile, INTENT_PERCEPTUAL);
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if (hRoundTrip == NULL) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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LabIn.L = LabIn.a = LabIn.b = 0;
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cmsDoTransform(hRoundTrip, &LabIn, &LabOut, 1);
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// Clip Lab to reasonable limits
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if (LabOut.L > 50) LabOut.L = 50;
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LabOut.a = LabOut.b = 0;
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cmsDeleteTransform(hRoundTrip);
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// Convert it to XYZ
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cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);
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if (BlackPoint != NULL)
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*BlackPoint = BlackXYZ;
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return TRUE;
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}
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// This function shouldn't exist at all -- there is such quantity of broken
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// profiles on black point tag, that we must somehow fix chromaticity to
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// avoid huge tint when doing Black point compensation. This function does
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// just that. There is a special flag for using black point tag, but turned
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// off by default because it is bogus on most profiles. The detection algorithm
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// involves to turn BP to neutral and to use only L component.
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cmsBool CMSEXPORT cmsDetectBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
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{
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// Zero for black point
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if (cmsGetDeviceClass(hProfile) == cmsSigLinkClass) {
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BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
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return FALSE;
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}
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// v4 + perceptual & saturation intents does have its own black point, and it is
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// well specified enough to use it. Black point tag is deprecated in V4.
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if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
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(Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
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// Matrix shaper share MRC & perceptual intents
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if (cmsIsMatrixShaper(hProfile))
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return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);
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// Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents
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BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;
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BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
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BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
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return TRUE;
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}
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#ifdef CMS_USE_PROFILE_BLACK_POINT_TAG
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// v2, v4 rel/abs colorimetric
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if (cmsIsTag(hProfile, cmsSigMediaBlackPointTag) &&
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Intent == INTENT_RELATIVE_COLORIMETRIC) {
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cmsCIEXYZ *BlackPtr, BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;
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cmsCIELab Lab;
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// If black point is specified, then use it,
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BlackPtr = cmsReadTag(hProfile, cmsSigMediaBlackPointTag);
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if (BlackPtr != NULL) {
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BlackXYZ = *BlackPtr;
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_cmsReadMediaWhitePoint(&MediaWhite, hProfile);
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// Black point is absolute XYZ, so adapt to D50 to get PCS value
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cmsAdaptToIlluminant(&UntrustedBlackPoint, &MediaWhite, cmsD50_XYZ(), &BlackXYZ);
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// Force a=b=0 to get rid of any chroma
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cmsXYZ2Lab(NULL, &Lab, &UntrustedBlackPoint);
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Lab.a = Lab.b = 0;
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if (Lab.L > 50) Lab.L = 50; // Clip to L* <= 50
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cmsLab2XYZ(NULL, &TrustedBlackPoint, &Lab);
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if (BlackPoint != NULL)
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*BlackPoint = TrustedBlackPoint;
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return TRUE;
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}
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}
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#endif
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// That is about v2 profiles.
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// If output profile, discount ink-limiting and that's all
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if (Intent == INTENT_RELATIVE_COLORIMETRIC &&
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(cmsGetDeviceClass(hProfile) == cmsSigOutputClass) &&
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(cmsGetColorSpace(hProfile) == cmsSigCmykData))
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return BlackPointUsingPerceptualBlack(BlackPoint, hProfile);
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// Nope, compute BP using current intent.
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return BlackPointAsDarkerColorant(hProfile, Intent, BlackPoint, dwFlags);
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}
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