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//---------------------------------------------------------------------------------
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// Little Color Management System
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// Copyright (c) 1998-2012 Marti Maria Saguer
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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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// 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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// 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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#include "lcms2_internal.h"
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// Auxiliar: append a Lab identity after the given sequence of profiles
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// and return the transform. Lab profile is closed, rest of profiles are kept open.
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cmsHTRANSFORM _cmsChain2Lab(cmsContext ContextID,
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cmsUInt32Number nProfiles,
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cmsUInt32Number InputFormat,
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cmsUInt32Number OutputFormat,
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const cmsUInt32Number Intents[],
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const cmsHPROFILE hProfiles[],
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const cmsFloat64Number AdaptationStates[],
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cmsUInt32Number dwFlags)
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cmsHPROFILE ProfileList[256];
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cmsFloat64Number AdaptationList[256];
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cmsUInt32Number IntentList[256];
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// This is a rather big number and there is no need of dynamic memory
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// since we are adding a profile, 254 + 1 = 255 and this is the limit
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if (nProfiles > 254) return NULL;
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hLab = cmsCreateLab4ProfileTHR(ContextID, NULL);
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if (hLab == NULL) return NULL;
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// Create a copy of parameters
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for (i=0; i < nProfiles; i++) {
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ProfileList[i] = hProfiles[i];
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AdaptationList[i] = AdaptationStates[i];
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IntentList[i] = Intents[i];
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// Place Lab identity at chain's end.
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ProfileList[nProfiles] = hLab;
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BPCList[nProfiles] = 0;
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AdaptationList[nProfiles] = 1.0;
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IntentList[nProfiles] = INTENT_RELATIVE_COLORIMETRIC;
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// Create the transform
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xform = cmsCreateExtendedTransform(ContextID, nProfiles + 1, ProfileList,
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cmsCloseProfile(hLab);
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// Compute K -> L* relationship. Flags may include black point compensation. In this case,
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// the relationship is assumed from the profile with BPC to a black point zero.
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cmsToneCurve* ComputeKToLstar(cmsContext ContextID,
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cmsUInt32Number nPoints,
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cmsUInt32Number nProfiles,
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const cmsUInt32Number Intents[],
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const cmsHPROFILE hProfiles[],
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const cmsFloat64Number AdaptationStates[],
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cmsUInt32Number dwFlags)
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cmsToneCurve* out = NULL;
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cmsFloat32Number cmyk[4];
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cmsFloat32Number* SampledPoints;
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xform = _cmsChain2Lab(ContextID, nProfiles, TYPE_CMYK_FLT, TYPE_Lab_DBL, Intents, hProfiles, BPC, AdaptationStates, dwFlags);
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if (xform == NULL) return NULL;
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SampledPoints = (cmsFloat32Number*) _cmsCalloc(ContextID, nPoints, sizeof(cmsFloat32Number));
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if (SampledPoints == NULL) goto Error;
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for (i=0; i < nPoints; i++) {
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cmyk[3] = (cmsFloat32Number) ((i * 100.0) / (nPoints-1));
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cmsDoTransform(xform, cmyk, &Lab, 1);
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SampledPoints[i]= (cmsFloat32Number) (1.0 - Lab.L / 100.0); // Negate K for easier operation
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out = cmsBuildTabulatedToneCurveFloat(ContextID, nPoints, SampledPoints);
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cmsDeleteTransform(xform);
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if (SampledPoints) _cmsFree(ContextID, SampledPoints);
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// Compute Black tone curve on a CMYK -> CMYK transform. This is done by
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// using the proof direction on both profiles to find K->L* relationship
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// then joining both curves. dwFlags may include black point compensation.
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cmsToneCurve* _cmsBuildKToneCurve(cmsContext ContextID,
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cmsUInt32Number nPoints,
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cmsUInt32Number nProfiles,
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const cmsUInt32Number Intents[],
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const cmsHPROFILE hProfiles[],
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const cmsFloat64Number AdaptationStates[],
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cmsUInt32Number dwFlags)
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cmsToneCurve *in, *out, *KTone;
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// Make sure CMYK -> CMYK
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if (cmsGetColorSpace(hProfiles[0]) != cmsSigCmykData ||
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cmsGetColorSpace(hProfiles[nProfiles-1])!= cmsSigCmykData) return NULL;
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// Make sure last is an output profile
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if (cmsGetDeviceClass(hProfiles[nProfiles - 1]) != cmsSigOutputClass) return NULL;
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// Create individual curves. BPC works also as each K to L* is
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// computed as a BPC to zero black point in case of L*
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in = ComputeKToLstar(ContextID, nPoints, nProfiles - 1, Intents, hProfiles, BPC, AdaptationStates, dwFlags);
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if (in == NULL) return NULL;
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out = ComputeKToLstar(ContextID, nPoints, 1,
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Intents + (nProfiles - 1),
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hProfiles + (nProfiles - 1),
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BPC + (nProfiles - 1),
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AdaptationStates + (nProfiles - 1),
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cmsFreeToneCurve(in);
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// Build the relationship. This effectively limits the maximum accuracy to 16 bits, but
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// since this is used on black-preserving LUTs, we are not loosing accuracy in any case
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KTone = cmsJoinToneCurve(ContextID, in, out, nPoints);
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// Get rid of components
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cmsFreeToneCurve(in); cmsFreeToneCurve(out);
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// Something went wrong...
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if (KTone == NULL) return NULL;
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// Make sure it is monotonic
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if (!cmsIsToneCurveMonotonic(KTone)) {
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cmsFreeToneCurve(KTone);
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// Gamut LUT Creation -----------------------------------------------------------------------------------------
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// Used by gamut & softproofing
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cmsHTRANSFORM hInput; // From whatever input color space. 16 bits to DBL
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cmsHTRANSFORM hForward, hReverse; // Transforms going from Lab to colorant and back
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cmsFloat64Number Thereshold; // The thereshold after which is considered out of gamut
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// This sampler does compute gamut boundaries by comparing original
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// values with a transform going back and forth. Values above ERR_THERESHOLD
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// of maximum are considered out of gamut.
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#define ERR_THERESHOLD 5
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int GamutSampler(register const cmsUInt16Number In[], register cmsUInt16Number Out[], register void* Cargo)
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GAMUTCHAIN* t = (GAMUTCHAIN* ) Cargo;
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cmsCIELab LabIn1, LabOut1;
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cmsCIELab LabIn2, LabOut2;
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cmsUInt16Number Proof[cmsMAXCHANNELS], Proof2[cmsMAXCHANNELS];
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cmsFloat64Number dE1, dE2, ErrorRatio;
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// Assume in-gamut by default.
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// Convert input to Lab
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if (t -> hInput != NULL)
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cmsDoTransform(t -> hInput, In, &LabIn1, 1);
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// converts from PCS to colorant. This always
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// does return in-gamut values,
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cmsDoTransform(t -> hForward, &LabIn1, Proof, 1);
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// Now, do the inverse, from colorant to PCS.
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cmsDoTransform(t -> hReverse, Proof, &LabOut1, 1);
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memmove(&LabIn2, &LabOut1, sizeof(cmsCIELab));
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// Try again, but this time taking Check as input
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cmsDoTransform(t -> hForward, &LabOut1, Proof2, 1);
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cmsDoTransform(t -> hReverse, Proof2, &LabOut2, 1);
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// Take difference of direct value
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dE1 = cmsDeltaE(&LabIn1, &LabOut1);
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// Take difference of converted value
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dE2 = cmsDeltaE(&LabIn2, &LabOut2);
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// if dE1 is small and dE2 is small, value is likely to be in gamut
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if (dE1 < t->Thereshold && dE2 < t->Thereshold)
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// if dE1 is small and dE2 is big, undefined. Assume in gamut
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if (dE1 < t->Thereshold && dE2 > t->Thereshold)
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// dE1 is big and dE2 is small, clearly out of gamut
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if (dE1 > t->Thereshold && dE2 < t->Thereshold)
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Out[0] = (cmsUInt16Number) _cmsQuickFloor((dE1 - t->Thereshold) + .5);
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// dE1 is big and dE2 is also big, could be due to perceptual mapping
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// so take error ratio
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ErrorRatio = dE1 / dE2;
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if (ErrorRatio > t->Thereshold)
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Out[0] = (cmsUInt16Number) _cmsQuickFloor((ErrorRatio - t->Thereshold) + .5);
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// Does compute a gamut LUT going back and forth across pcs -> relativ. colorimetric intent -> pcs
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// the dE obtained is then annotated on the LUT. Values truely out of gamut are clipped to dE = 0xFFFE
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// and values changed are supposed to be handled by any gamut remapping, so, are out of gamut as well.
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// **WARNING: This algorithm does assume that gamut remapping algorithms does NOT move in-gamut colors,
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// of course, many perceptual and saturation intents does not work in such way, but relativ. ones should.
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cmsPipeline* _cmsCreateGamutCheckPipeline(cmsContext ContextID,
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cmsHPROFILE hProfiles[],
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cmsUInt32Number Intents[],
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cmsFloat64Number AdaptationStates[],
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cmsUInt32Number nGamutPCSposition,
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cmsUInt32Number dwFormat;
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int nChannels, nGridpoints;
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cmsColorSpaceSignature ColorSpace;
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cmsHPROFILE ProfileList[256];
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cmsBool BPCList[256];
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cmsFloat64Number AdaptationList[256];
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cmsUInt32Number IntentList[256];
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memset(&Chain, 0, sizeof(GAMUTCHAIN));
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if (nGamutPCSposition <= 0 || nGamutPCSposition > 255) {
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cmsSignalError(ContextID, cmsERROR_RANGE, "Wrong position of PCS. 1..255 expected, %d found.", nGamutPCSposition);
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hLab = cmsCreateLab4ProfileTHR(ContextID, NULL);
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if (hLab == NULL) return NULL;
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// The figure of merit. On matrix-shaper profiles, should be almost zero as
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// the conversion is pretty exact. On LUT based profiles, different resolutions
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// of input and output CLUT may result in differences.
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if (cmsIsMatrixShaper(hGamut)) {
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Chain.Thereshold = 1.0;
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Chain.Thereshold = ERR_THERESHOLD;
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// Create a copy of parameters
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for (i=0; i < nGamutPCSposition; i++) {
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ProfileList[i] = hProfiles[i];
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AdaptationList[i] = AdaptationStates[i];
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IntentList[i] = Intents[i];
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ProfileList[nGamutPCSposition] = hLab;
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BPCList[nGamutPCSposition] = 0;
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AdaptationList[nGamutPCSposition] = 1.0;
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Intents[nGamutPCSposition] = INTENT_RELATIVE_COLORIMETRIC;
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ColorSpace = cmsGetColorSpace(hGamut);
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nChannels = cmsChannelsOf(ColorSpace);
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nGridpoints = _cmsReasonableGridpointsByColorspace(ColorSpace, cmsFLAGS_HIGHRESPRECALC);
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dwFormat = (CHANNELS_SH(nChannels)|BYTES_SH(2));
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// 16 bits to Lab double
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Chain.hInput = cmsCreateExtendedTransform(ContextID,
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nGamutPCSposition + 1,
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dwFormat, TYPE_Lab_DBL,
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// Does create the forward step. Lab double to device
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dwFormat = (CHANNELS_SH(nChannels)|BYTES_SH(2));
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Chain.hForward = cmsCreateTransformTHR(ContextID,
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INTENT_RELATIVE_COLORIMETRIC,
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// Does create the backwards step
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Chain.hReverse = cmsCreateTransformTHR(ContextID, hGamut, dwFormat,
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INTENT_RELATIVE_COLORIMETRIC,
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if (Chain.hForward && Chain.hReverse) {
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// Go on, try to compute gamut LUT from PCS. This consist on a single channel containing
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// dE when doing a transform back and forth on the colorimetric intent.
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Gamut = cmsPipelineAlloc(ContextID, 3, 1);
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CLUT = cmsStageAllocCLut16bit(ContextID, nGridpoints, nChannels, 1, NULL);
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cmsPipelineInsertStage(Gamut, cmsAT_BEGIN, CLUT);
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cmsStageSampleCLut16bit(CLUT, GamutSampler, (void*) &Chain, 0);
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Gamut = NULL; // Didn't work...
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// Free all needed stuff.
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if (Chain.hInput) cmsDeleteTransform(Chain.hInput);
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if (Chain.hForward) cmsDeleteTransform(Chain.hForward);
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if (Chain.hReverse) cmsDeleteTransform(Chain.hReverse);
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if (hLab) cmsCloseProfile(hLab);
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// And return computed hull
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// Total Area Coverage estimation ----------------------------------------------------------------
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cmsUInt32Number nOutputChans;
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cmsHTRANSFORM hRoundTrip;
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cmsFloat32Number MaxTAC;
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cmsFloat32Number MaxInput[cmsMAXCHANNELS];
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// This callback just accounts the maximum ink dropped in the given node. It does not populate any
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// memory, as the destination table is NULL. Its only purpose it to know the global maximum.
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int EstimateTAC(register const cmsUInt16Number In[], register cmsUInt16Number Out[], register void * Cargo)
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cmsTACestimator* bp = (cmsTACestimator*) Cargo;
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cmsFloat32Number RoundTrip[cmsMAXCHANNELS];
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cmsFloat32Number Sum;
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// Evaluate the xform
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cmsDoTransform(bp->hRoundTrip, In, RoundTrip, 1);
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// All all amounts of ink
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for (Sum=0, i=0; i < bp ->nOutputChans; i++)
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// If above maximum, keep track of input values
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if (Sum > bp ->MaxTAC) {
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for (i=0; i < bp ->nOutputChans; i++) {
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bp ->MaxInput[i] = In[i];
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cmsUNUSED_PARAMETER(Out);
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// Detect Total area coverage of the profile
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cmsFloat64Number CMSEXPORT cmsDetectTAC(cmsHPROFILE hProfile)
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cmsUInt32Number dwFormatter;
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cmsUInt32Number GridPoints[MAX_INPUT_DIMENSIONS];
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cmsContext ContextID = cmsGetProfileContextID(hProfile);
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// TAC only works on output profiles
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if (cmsGetDeviceClass(hProfile) != cmsSigOutputClass) {
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// Create a fake formatter for result
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dwFormatter = cmsFormatterForColorspaceOfProfile(hProfile, 4, TRUE);
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bp.nOutputChans = T_CHANNELS(dwFormatter);
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bp.MaxTAC = 0; // Initial TAC is 0
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if (bp.nOutputChans >= cmsMAXCHANNELS) return 0;
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hLab = cmsCreateLab4ProfileTHR(ContextID, NULL);
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if (hLab == NULL) return 0;
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// Setup a roundtrip on perceptual intent in output profile for TAC estimation
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bp.hRoundTrip = cmsCreateTransformTHR(ContextID, hLab, TYPE_Lab_16,
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hProfile, dwFormatter, INTENT_PERCEPTUAL, cmsFLAGS_NOOPTIMIZE|cmsFLAGS_NOCACHE);
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cmsCloseProfile(hLab);
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if (bp.hRoundTrip == NULL) return 0;
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// For L* we only need black and white. For C* we need many points
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if (!cmsSliceSpace16(3, GridPoints, EstimateTAC, &bp)) {
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cmsDeleteTransform(bp.hRoundTrip);
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// Carefully, clamp on CIELab space.
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cmsBool CMSEXPORT cmsDesaturateLab(cmsCIELab* Lab,
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double amax, double amin,
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double bmax, double bmin)
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// Whole Luma surface to zero
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Lab-> L = Lab->a = Lab-> b = 0.0;
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// Clamp white, DISCARD HIGHLIGHTS. This is done
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// in such way because icc spec doesn't allow the
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// use of L>100 as a highlight means.
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// Check out gamut prism, on a, b faces
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if (Lab -> a < amin || Lab->a > amax||
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Lab -> b < bmin || Lab->b > bmax) {
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// Falls outside a, b limits. Transports to LCh space,
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// and then do the clipping
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if (Lab -> a == 0.0) { // Is hue exactly 90?
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// atan will not work, so clamp here
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Lab -> b = Lab->b < 0 ? bmin : bmax;
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cmsLab2LCh(&LCh, Lab);
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slope = Lab -> b / Lab -> a;
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if ((h >= 0. && h < 45.) ||
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(h >= 315 && h <= 360.)) {
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Lab -> b = amax * slope;
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if (h >= 45. && h < 135.)
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Lab -> a = bmax / slope;
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if (h >= 135. && h < 225.) {
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Lab -> b = amin * slope;
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if (h >= 225. && h < 315.) {
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Lab -> a = bmin / slope;
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cmsSignalError(0, cmsERROR_RANGE, "Invalid angle");
added
removed
lcms2/src/cmsgmt.c
