static
int WriteInputMatrixShaper(cmsIOHANDLER* m, cmsHPROFILE hProfile, cmsStage* Matrix, cmsStage* Shaper)
{
cmsColorSpaceSignature ColorSpace;
int rc;
cmsCIEXYZ BlackPointAdaptedToD50;
ColorSpace = cmsGetColorSpace(hProfile);
cmsDetectBlackPoint(&BlackPointAdaptedToD50, hProfile, INTENT_RELATIVE_COLORIMETRIC, 0);
if (ColorSpace == cmsSigGrayData) {
cmsToneCurve** ShaperCurve = _cmsStageGetPtrToCurveSet(Shaper);
rc = EmitCIEBasedA(m, ShaperCurve[0], &BlackPointAdaptedToD50);
}
else
if (ColorSpace == cmsSigRgbData) {
rc = EmitCIEBasedABC(m, GetPtrToMatrix(Matrix),
_cmsStageGetPtrToCurveSet(Shaper),
&BlackPointAdaptedToD50);
}
else {
cmsSignalError(m ->ContextID, cmsERROR_COLORSPACE_CHECK, "Profile is not suitable for CSA. Unsupported colorspace.");
return 0;
}
return rc;
}
static
int WriteInputMatrixShaper(cmsIOHANDLER* m, cmsHPROFILE hProfile, cmsStage* Matrix, cmsStage* Shaper)
{
cmsColorSpaceSignature ColorSpace;
int rc;
cmsCIEXYZ BlackPointAdaptedToD50;
ColorSpace = cmsGetColorSpace(hProfile);
cmsDetectBlackPoint(&BlackPointAdaptedToD50, hProfile, INTENT_RELATIVE_COLORIMETRIC, 0);
if (ColorSpace == cmsSigGrayData) {
cmsToneCurve** ShaperCurve = _cmsStageGetPtrToCurveSet(Shaper);
rc = EmitCIEBasedA(m, ShaperCurve[0], &BlackPointAdaptedToD50);
}
else
if (ColorSpace == cmsSigRgbData) {
cmsMAT3 Mat;
int i, j;
memmove(&Mat, GetPtrToMatrix(Matrix), sizeof(Mat));
for (i=0; i < 3; i++)
for (j=0; j < 3; j++)
Mat.v[i].n[j] *= MAX_ENCODEABLE_XYZ;
rc = EmitCIEBasedABC(m, (cmsFloat64Number *) &Mat,
_cmsStageGetPtrToCurveSet(Shaper),
&BlackPointAdaptedToD50);
}
else {
cmsSignalError(m ->ContextID, cmsERROR_COLORSPACE_CHECK, "Profile is not suitable for CSA. Unsupported colorspace.");
return 0;
}
return rc;
}
static
int WriteInputLUT(cmsIOHANDLER* m, cmsHPROFILE hProfile, int Intent, cmsUInt32Number dwFlags)
{
cmsHPROFILE hLab;
cmsHTRANSFORM xform;
cmsUInt32Number nChannels;
cmsUInt32Number InputFormat;
int rc;
cmsHPROFILE Profiles[2];
cmsCIEXYZ BlackPointAdaptedToD50;
// Does create a device-link based transform.
// The DeviceLink is next dumped as working CSA.
InputFormat = cmsFormatterForColorspaceOfProfile(hProfile, 2, FALSE);
nChannels = T_CHANNELS(InputFormat);
cmsDetectBlackPoint(&BlackPointAdaptedToD50, hProfile, Intent, 0);
// Adjust output to Lab4
hLab = cmsCreateLab4ProfileTHR(m ->ContextID, NULL);
Profiles[0] = hProfile;
Profiles[1] = hLab;
xform = cmsCreateMultiprofileTransform(Profiles, 2, InputFormat, TYPE_Lab_DBL, Intent, 0);
cmsCloseProfile(hLab);
if (xform == NULL) {
cmsSignalError(m ->ContextID, cmsERROR_COLORSPACE_CHECK, "Cannot create transform Profile -> Lab");
return 0;
}
// Only 1, 3 and 4 channels are allowed
switch (nChannels) {
case 1: {
cmsToneCurve* Gray2Y = ExtractGray2Y(m ->ContextID, hProfile, Intent);
EmitCIEBasedA(m, Gray2Y, &BlackPointAdaptedToD50);
cmsFreeToneCurve(Gray2Y);
}
break;
case 3:
case 4: {
cmsUInt32Number OutFrm = TYPE_Lab_16;
cmsPipeline* DeviceLink;
_cmsTRANSFORM* v = (_cmsTRANSFORM*) xform;
DeviceLink = cmsPipelineDup(v ->Lut);
if (DeviceLink == NULL) return 0;
dwFlags |= cmsFLAGS_FORCE_CLUT;
_cmsOptimizePipeline(&DeviceLink, Intent, &InputFormat, &OutFrm, &dwFlags);
rc = EmitCIEBasedDEF(m, DeviceLink, Intent, &BlackPointAdaptedToD50);
cmsPipelineFree(DeviceLink);
}
break;
default:
cmsSignalError(m ->ContextID, cmsERROR_COLORSPACE_CHECK, "Only 3, 4 channels supported for CSA. This profile has %d channels.", nChannels);
return 0;
}
cmsDeleteTransform(xform);
return 1;
}
static
int WriteOutputLUT(cmsIOHANDLER* m, cmsHPROFILE hProfile, int Intent, cmsUInt32Number dwFlags)
{
cmsHPROFILE hLab;
cmsHTRANSFORM xform;
int i, nChannels;
cmsUInt32Number OutputFormat;
_cmsTRANSFORM* v;
cmsPipeline* DeviceLink;
cmsHPROFILE Profiles[3];
cmsCIEXYZ BlackPointAdaptedToD50;
cmsBool lDoBPC = (dwFlags & cmsFLAGS_BLACKPOINTCOMPENSATION);
cmsBool lFixWhite = !(dwFlags & cmsFLAGS_NOWHITEONWHITEFIXUP);
cmsUInt32Number InFrm = TYPE_Lab_16;
int RelativeEncodingIntent;
cmsColorSpaceSignature ColorSpace;
hLab = cmsCreateLab4ProfileTHR(m ->ContextID, NULL);
if (hLab == NULL) return 0;
OutputFormat = cmsFormatterForColorspaceOfProfile(hProfile, 2, FALSE);
nChannels = T_CHANNELS(OutputFormat);
ColorSpace = cmsGetColorSpace(hProfile);
// For absolute colorimetric, the LUT is encoded as relative in order to preserve precision.
RelativeEncodingIntent = Intent;
if (RelativeEncodingIntent == INTENT_ABSOLUTE_COLORIMETRIC)
RelativeEncodingIntent = INTENT_RELATIVE_COLORIMETRIC;
// Use V4 Lab always
Profiles[0] = hLab;
Profiles[1] = hProfile;
xform = cmsCreateMultiprofileTransformTHR(m ->ContextID,
Profiles, 2, TYPE_Lab_DBL,
OutputFormat, RelativeEncodingIntent, 0);
cmsCloseProfile(hLab);
if (xform == NULL) {
cmsSignalError(m ->ContextID, cmsERROR_COLORSPACE_CHECK, "Cannot create transform Lab -> Profile in CRD creation");
return 0;
}
// Get a copy of the internal devicelink
v = (_cmsTRANSFORM*) xform;
DeviceLink = cmsPipelineDup(v ->Lut);
if (DeviceLink == NULL) return 0;
// We need a CLUT
dwFlags |= cmsFLAGS_FORCE_CLUT;
_cmsOptimizePipeline(&DeviceLink, RelativeEncodingIntent, &InFrm, &OutputFormat, &dwFlags);
_cmsIOPrintf(m, "<<\n");
_cmsIOPrintf(m, "/ColorRenderingType 1\n");
cmsDetectBlackPoint(&BlackPointAdaptedToD50, hProfile, Intent, 0);
// Emit headers, etc.
EmitWhiteBlackD50(m, &BlackPointAdaptedToD50);
EmitPQRStage(m, hProfile, lDoBPC, Intent == INTENT_ABSOLUTE_COLORIMETRIC);
EmitXYZ2Lab(m);
// FIXUP: map Lab (100, 0, 0) to perfect white, because the particular encoding for Lab
// does map a=b=0 not falling into any specific node. Since range a,b goes -128..127,
// zero is slightly moved towards right, so assure next node (in L=100 slice) is mapped to
// zero. This would sacrifice a bit of highlights, but failure to do so would cause
// scum dot. Ouch.
if (Intent == INTENT_ABSOLUTE_COLORIMETRIC)
lFixWhite = FALSE;
_cmsIOPrintf(m, "/RenderTable ");
WriteCLUT(m, cmsPipelineGetPtrToFirstStage(DeviceLink), "<", ">\n", "", "", lFixWhite, ColorSpace);
_cmsIOPrintf(m, " %d {} bind ", nChannels);
for (i=1; i < nChannels; i++)
_cmsIOPrintf(m, "dup ");
_cmsIOPrintf(m, "]\n");
EmitIntent(m, Intent);
_cmsIOPrintf(m, ">>\n");
if (!(dwFlags & cmsFLAGS_NODEFAULTRESOURCEDEF)) {
_cmsIOPrintf(m, "/Current exch /ColorRendering defineresource pop\n");
}
cmsPipelineFree(DeviceLink);
cmsDeleteTransform(xform);
return 1;
}
// Compute the conversion layer
static
cmsBool ComputeConversion(int i, cmsHPROFILE hProfiles[],
cmsUInt32Number Intent,
cmsBool BPC,
cmsFloat64Number AdaptationState,
cmsMAT3* m, cmsVEC3* off)
{
int k;
// m and off are set to identity and this is detected latter on
_cmsMAT3identity(m);
_cmsVEC3init(off, 0, 0, 0);
// If intent is abs. colorimetric,
if (Intent == INTENT_ABSOLUTE_COLORIMETRIC) {
cmsCIEXYZ WhitePointIn, WhitePointOut;
cmsMAT3 ChromaticAdaptationMatrixIn, ChromaticAdaptationMatrixOut;
_cmsReadMediaWhitePoint(&WhitePointIn, hProfiles[i-1]);
_cmsReadCHAD(&ChromaticAdaptationMatrixIn, hProfiles[i-1]);
_cmsReadMediaWhitePoint(&WhitePointOut, hProfiles[i]);
_cmsReadCHAD(&ChromaticAdaptationMatrixOut, hProfiles[i]);
if (!ComputeAbsoluteIntent(AdaptationState,
&WhitePointIn, &ChromaticAdaptationMatrixIn,
&WhitePointOut, &ChromaticAdaptationMatrixOut, m)) return FALSE;
}
else {
// Rest of intents may apply BPC.
if (BPC) {
cmsCIEXYZ BlackPointIn, BlackPointOut;
cmsDetectBlackPoint(&BlackPointIn, hProfiles[i-1], Intent, 0);
cmsDetectDestinationBlackPoint(&BlackPointOut, hProfiles[i], Intent, 0);
// If black points are equal, then do nothing
if (BlackPointIn.X != BlackPointOut.X ||
BlackPointIn.Y != BlackPointOut.Y ||
BlackPointIn.Z != BlackPointOut.Z)
ComputeBlackPointCompensation(&BlackPointIn, &BlackPointOut, m, off);
}
}
// Offset should be adjusted because the encoding. We encode XYZ normalized to 0..1.0,
// to do that, we divide by MAX_ENCODEABLE_XZY. The conversion stage goes XYZ -> XYZ so
// we have first to convert from encoded to XYZ and then convert back to encoded.
// y = Mx + Off
// x = x'c
// y = M x'c + Off
// y = y'c; y' = y / c
// y' = (Mx'c + Off) /c = Mx' + (Off / c)
for (k=0; k < 3; k++) {
off ->n[k] /= MAX_ENCODEABLE_XYZ;
}
return TRUE;
}
// Calculates the black point of a destination profile.
// This algorithm comes from the Adobe paper disclosing its black point compensation method.
cmsBool CMSEXPORT cmsDetectDestinationBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
{
cmsColorSpaceSignature ColorSpace;
cmsHTRANSFORM hRoundTrip = NULL;
cmsCIELab InitialLab, destLab, Lab;
cmsFloat64Number inRamp[256], outRamp[256];
cmsFloat64Number MinL, MaxL;
cmsBool NearlyStraightMidrange = TRUE;
cmsFloat64Number yRamp[256];
cmsFloat64Number x[256], y[256];
cmsFloat64Number lo, hi;
int n, l;
cmsProfileClassSignature devClass;
// Make sure the device class is adequate
devClass = cmsGetDeviceClass(hProfile);
if (devClass == cmsSigLinkClass ||
devClass == cmsSigAbstractClass ||
devClass == cmsSigNamedColorClass) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
// Make sure intent is adequate
if (Intent != INTENT_PERCEPTUAL &&
Intent != INTENT_RELATIVE_COLORIMETRIC &&
Intent != INTENT_SATURATION) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
// v4 + perceptual & saturation intents does have its own black point, and it is
// well specified enough to use it. Black point tag is deprecated in V4.
if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
(Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
// Matrix shaper share MRC & perceptual intents
if (cmsIsMatrixShaper(hProfile))
return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);
// Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents
BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;
BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
return TRUE;
}
// Check if the profile is lut based and gray, rgb or cmyk (7.2 in Adobe's document)
ColorSpace = cmsGetColorSpace(hProfile);
if (!cmsIsCLUT(hProfile, Intent, LCMS_USED_AS_OUTPUT ) ||
(ColorSpace != cmsSigGrayData &&
ColorSpace != cmsSigRgbData &&
ColorSpace != cmsSigCmykData)) {
// In this case, handle as input case
return cmsDetectBlackPoint(BlackPoint, hProfile, Intent, dwFlags);
}
// It is one of the valid cases!, use Adobe algorithm
// Set a first guess, that should work on good profiles.
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
cmsCIEXYZ IniXYZ;
// calculate initial Lab as source black point
if (!cmsDetectBlackPoint(&IniXYZ, hProfile, Intent, dwFlags)) {
return FALSE;
}
// convert the XYZ to lab
cmsXYZ2Lab(NULL, &InitialLab, &IniXYZ);
} else {
// set the initial Lab to zero, that should be the black point for perceptual and saturation
InitialLab.L = 0;
InitialLab.a = 0;
InitialLab.b = 0;
}
// Step 2
// ======
// Create a roundtrip. Define a Transform BT for all x in L*a*b*
hRoundTrip = CreateRoundtripXForm(hProfile, Intent);
if (hRoundTrip == NULL) return FALSE;
// Compute ramps
for (l=0; l < 256; l++) {
Lab.L = (cmsFloat64Number) (l * 100.0) / 255.0;
Lab.a = cmsmin(50, cmsmax(-50, InitialLab.a));
Lab.b = cmsmin(50, cmsmax(-50, InitialLab.b));
cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
inRamp[l] = Lab.L;
outRamp[l] = destLab.L;
}
// Make monotonic
for (l = 254; l > 0; --l) {
outRamp[l] = cmsmin(outRamp[l], outRamp[l+1]);
}
// Check
if (! (outRamp[0] < outRamp[255])) {
cmsDeleteTransform(hRoundTrip);
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
// Test for mid range straight (only on relative colorimetric)
NearlyStraightMidrange = TRUE;
MinL = outRamp[0]; MaxL = outRamp[255];
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
for (l=0; l < 256; l++) {
if (! ((inRamp[l] <= MinL + 0.2 * (MaxL - MinL) ) ||
(fabs(inRamp[l] - outRamp[l]) < 4.0 )))
NearlyStraightMidrange = FALSE;
}
// If the mid range is straight (as determined above) then the
// DestinationBlackPoint shall be the same as initialLab.
// Otherwise, the DestinationBlackPoint shall be determined
// using curve fitting.
if (NearlyStraightMidrange) {
cmsLab2XYZ(NULL, BlackPoint, &InitialLab);
cmsDeleteTransform(hRoundTrip);
return TRUE;
}
}
// curve fitting: The round-trip curve normally looks like a nearly constant section at the black point,
// with a corner and a nearly straight line to the white point.
for (l=0; l < 256; l++) {
yRamp[l] = (outRamp[l] - MinL) / (MaxL - MinL);
}
// find the black point using the least squares error quadratic curve fitting
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
lo = 0.1;
hi = 0.5;
}
else {
// Perceptual and saturation
lo = 0.03;
hi = 0.25;
}
// Capture shadow points for the fitting.
n = 0;
for (l=0; l < 256; l++) {
cmsFloat64Number ff = yRamp[l];
if (ff >= lo && ff < hi) {
x[n] = inRamp[l];
y[n] = yRamp[l];
n++;
}
}
// No suitable points
if (n < 3 ) {
cmsDeleteTransform(hRoundTrip);
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
// fit and get the vertex of quadratic curve
Lab.L = RootOfLeastSquaresFitQuadraticCurve(n, x, y);
if (Lab.L < 0.0) { // clip to zero L* if the vertex is negative
Lab.L = 0;
}
Lab.a = InitialLab.a;
Lab.b = InitialLab.b;
cmsLab2XYZ(NULL, BlackPoint, &Lab);
cmsDeleteTransform(hRoundTrip);
return TRUE;
}
// Calculates the black point of a destination profile.
// This algorithm comes from the Adobe paper disclosing its black point compensation method.
cmsBool CMSEXPORT cmsDetectDestinationBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
{
cmsColorSpaceSignature ColorSpace;
cmsHTRANSFORM hRoundTrip = NULL;
cmsCIELab InitialLab, destLab, Lab;
cmsFloat64Number MinL, MaxL;
cmsBool NearlyStraightMidRange = FALSE;
cmsFloat64Number L;
cmsFloat64Number x[101], y[101];
cmsFloat64Number lo, hi, NonMonoMin;
int n, l, i, NonMonoIndx;
// Make sure intent is adequate
if (Intent != INTENT_PERCEPTUAL &&
Intent != INTENT_RELATIVE_COLORIMETRIC &&
Intent != INTENT_SATURATION) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
// v4 + perceptual & saturation intents does have its own black point, and it is
// well specified enough to use it. Black point tag is deprecated in V4.
if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
(Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
// Matrix shaper share MRC & perceptual intents
if (cmsIsMatrixShaper(hProfile))
return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, 0);
// Get Perceptual black out of v4 profiles. That is fixed for perceptual & saturation intents
BlackPoint -> X = cmsPERCEPTUAL_BLACK_X;
BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
return TRUE;
}
// Check if the profile is lut based and gray, rgb or cmyk (7.2 in Adobe's document)
ColorSpace = cmsGetColorSpace(hProfile);
if (!cmsIsCLUT(hProfile, Intent, LCMS_USED_AS_OUTPUT ) ||
(ColorSpace != cmsSigGrayData &&
ColorSpace != cmsSigRgbData &&
ColorSpace != cmsSigCmykData)) {
// In this case, handle as input case
return cmsDetectBlackPoint(BlackPoint, hProfile, Intent, dwFlags);
}
// It is one of the valid cases!, presto chargo hocus pocus, go for the Adobe magic
// Step 1
// ======
// Set a first guess, that should work on good profiles.
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
cmsCIEXYZ IniXYZ;
// calculate initial Lab as source black point
if (!cmsDetectBlackPoint(&IniXYZ, hProfile, Intent, dwFlags)) {
return FALSE;
}
// convert the XYZ to lab
cmsXYZ2Lab(NULL, &InitialLab, &IniXYZ);
} else {
// set the initial Lab to zero, that should be the black point for perceptual and saturation
InitialLab.L = 0;
InitialLab.a = 0;
InitialLab.b = 0;
}
// Step 2
// ======
// Create a roundtrip. Define a Transform BT for all x in L*a*b*
hRoundTrip = CreateRoundtripXForm(hProfile, Intent);
if (hRoundTrip == NULL) return FALSE;
// Calculate Min L*
Lab = InitialLab;
Lab.L = 0;
cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
MinL = destLab.L;
// Calculate Max L*
Lab = InitialLab;
Lab.L = 100;
cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
MaxL = destLab.L;
// Step 3
// ======
// check if quadratic estimation needs to be done.
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
// Conceptually, this code tests how close the source l and converted L are to one another in the mid-range
// of the values. If the converted ramp of L values is close enough to a straight line y=x, then InitialLab
// is good enough to be the DestinationBlackPoint,
NearlyStraightMidRange = TRUE;
for (l=0; l <= 100; l++) {
Lab.L = l;
Lab.a = InitialLab.a;
Lab.b = InitialLab.b;
cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
L = destLab.L;
// Check the mid range in 20% after MinL
if (L > (MinL + 0.2 * (MaxL - MinL))) {
// Is close enough?
if (fabs(L - l) > 4.0) {
// Too far away, profile is buggy!
NearlyStraightMidRange = FALSE;
break;
}
}
}
}
else {
// Check is always performed for perceptual and saturation intents
NearlyStraightMidRange = FALSE;
}
// If no furter checking is needed, we are done
if (NearlyStraightMidRange) {
cmsLab2XYZ(NULL, BlackPoint, &InitialLab);
cmsDeleteTransform(hRoundTrip);
return TRUE;
}
// The round-trip curve normally looks like a nearly constant section at the black point,
// with a corner and a nearly straight line to the white point.
// STEP 4
// =======
// find the black point using the least squares error quadratic curve fitting
if (Intent == INTENT_RELATIVE_COLORIMETRIC) {
lo = 0.1;
hi = 0.5;
}
else {
// Perceptual and saturation
lo = 0.03;
hi = 0.25;
}
// Capture points for the fitting.
n = 0;
for (l=0; l <= 100; l++) {
cmsFloat64Number ff;
Lab.L = (cmsFloat64Number) l;
Lab.a = InitialLab.a;
Lab.b = InitialLab.b;
cmsDoTransform(hRoundTrip, &Lab, &destLab, 1);
ff = (destLab.L - MinL)/(MaxL - MinL);
if (ff >= lo && ff < hi) {
x[n] = Lab.L;
y[n] = ff;
n++;
}
}
// This part is not on the Adobe paper, but I found is necessary for getting any result.
if (IsMonotonic(n, y)) {
// Monotonic means lower point is stil valid
cmsLab2XYZ(NULL, BlackPoint, &InitialLab);
cmsDeleteTransform(hRoundTrip);
return TRUE;
}
// No suitable points, regret and use safer algorithm
if (n == 0) {
cmsDeleteTransform(hRoundTrip);
return cmsDetectBlackPoint(BlackPoint, hProfile, Intent, dwFlags);
}
NonMonoMin = 100;
NonMonoIndx = 0;
for (i=0; i < n; i++) {
if (y[i] < NonMonoMin) {
NonMonoIndx = i;
NonMonoMin = y[i];
}
}
Lab.L = x[NonMonoIndx];
// fit and get the vertex of quadratic curve
Lab.L = VertexOfLeastSquaresFitQuadraticCurve(n, x, y);
if (Lab.L < 0.0 || Lab.L > 50.0) { // clip to zero L* if the vertex is negative
Lab.L = 0;
}
Lab.a = InitialLab.a;
Lab.b = InitialLab.b;
cmsLab2XYZ(NULL, BlackPoint, &Lab);
cmsDeleteTransform(hRoundTrip);
return TRUE;
}
