// Little Color Management System
// Copyright (c) 1998-2010 Marti Maria Saguer
//
-// Permission is hereby granted, free of charge, to any person obtaining
-// a copy of this software and associated documentation files (the "Software"),
-// to deal in the Software without restriction, including without limitation
-// the rights to use, copy, modify, merge, publish, distribute, sublicense,
-// and/or sell copies of the Software, and to permit persons to whom the Software
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
-// The above copyright notice and this permission notice shall be included in
+// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
-// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
+// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//---------------------------------------------------------------------------------
// This file contains routines for resampling and LUT optimization, black point detection
-// and black preservation.
+// and black preservation.
// Black point detection -------------------------------------------------------------------------
-// PCS -> PCS round trip transform, always uses relative intent on the device -> pcs
+// PCS -> PCS round trip transform, always uses relative intent on the device -> pcs
static
cmsHTRANSFORM CreateRoundtripXForm(cmsHPROFILE hProfile, cmsUInt32Number nIntent)
{
hProfiles[0] = hLab; hProfiles[1] = hProfile; hProfiles[2] = hProfile; hProfiles[3] = hLab;
Intents[0] = INTENT_RELATIVE_COLORIMETRIC; Intents[1] = nIntent; Intents[2] = INTENT_RELATIVE_COLORIMETRIC; Intents[3] = INTENT_RELATIVE_COLORIMETRIC;
- xform = cmsCreateExtendedTransform(ContextID, 4, hProfiles, BPC, Intents,
+ xform = cmsCreateExtendedTransform(ContextID, 4, hProfiles, BPC, Intents,
States, NULL, 0, TYPE_Lab_DBL, TYPE_Lab_DBL, cmsFLAGS_NOCACHE|cmsFLAGS_NOOPTIMIZE);
cmsCloseProfile(hLab);
// Use darker colorants to obtain black point. This works in the relative colorimetric intent and
// assumes more ink results in darker colors. No ink limit is assumed.
static
-cmsBool BlackPointAsDarkerColorant(cmsHPROFILE hInput,
+cmsBool BlackPointAsDarkerColorant(cmsHPROFILE hInput,
cmsUInt32Number Intent,
cmsCIEXYZ* BlackPoint,
cmsUInt32Number dwFlags)
cmsHTRANSFORM xform;
cmsColorSpaceSignature Space;
cmsUInt32Number nChannels;
- cmsUInt32Number dwFormat;
+ cmsUInt32Number dwFormat;
cmsHPROFILE hLab;
cmsCIELab Lab;
- cmsCIEXYZ BlackXYZ;
+ cmsCIEXYZ BlackXYZ;
cmsContext ContextID = cmsGetProfileContextID(hInput);
-
- // If the profile does not support input direction, assume Black point 0
+
+ // If the profile does not support input direction, assume Black point 0
if (!cmsIsIntentSupported(hInput, Intent, LCMS_USED_AS_INPUT)) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
-
+
// Create a formatter which has n channels and floating point
dwFormat = cmsFormatterForColorspaceOfProfile(hInput, 2, FALSE);
- // Try to get black by using black colorant
+ // Try to get black by using black colorant
Space = cmsGetColorSpace(hInput);
// This function returns darker colorant in 16 bits for several spaces
if (!_cmsEndPointsBySpace(Space, NULL, &Black, &nChannels)) {
-
+
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
hLab = cmsCreateLab2ProfileTHR(ContextID, NULL);
if (hLab == NULL) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
- return FALSE;
+ return FALSE;
}
// Create the transform
xform = cmsCreateTransformTHR(ContextID, hInput, dwFormat,
hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOOPTIMIZE|cmsFLAGS_NOCACHE);
cmsCloseProfile(hLab);
-
+
if (xform == NULL) {
// Something went wrong. Get rid of open resources and return zero as black
-
+
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return FALSE;
}
-
+
// Convert black to Lab
cmsDoTransform(xform, Black, &Lab, 1);
Lab.a = Lab.b = 0;
if (Lab.L > 50) Lab.L = 50;
- // Free the resources
+ // Free the resources
cmsDeleteTransform(xform);
-
+
// Convert from Lab (which is now clipped) to XYZ.
cmsLab2XYZ(NULL, &BlackXYZ, &Lab);
-
+
if (BlackPoint != NULL)
*BlackPoint = BlackXYZ;
-
+
return TRUE;
cmsUNUSED_PARAMETER(dwFlags);
}
-// Get a black point of output CMYK profile, discounting any ink-limiting embedded
+// Get a black point of output CMYK profile, discounting any ink-limiting embedded
// in the profile. For doing that, we use perceptual intent in input direction:
// Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab
static
cmsBool BlackPointUsingPerceptualBlack(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile)
-
-{
- cmsHTRANSFORM hRoundTrip;
+
+{
+ cmsHTRANSFORM hRoundTrip;
cmsCIELab LabIn, LabOut;
- cmsCIEXYZ BlackXYZ;
-
+ cmsCIEXYZ BlackXYZ;
+
// Is the intent supported by the profile?
if (!cmsIsIntentSupported(hProfile, INTENT_PERCEPTUAL, LCMS_USED_AS_INPUT)) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
return TRUE;
}
-
+
hRoundTrip = CreateRoundtripXForm(hProfile, INTENT_PERCEPTUAL);
if (hRoundTrip == NULL) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
LabOut.a = LabOut.b = 0;
cmsDeleteTransform(hRoundTrip);
-
+
// Convert it to XYZ
- cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);
-
+ cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);
+
if (BlackPoint != NULL)
*BlackPoint = BlackXYZ;
}
// This function shouldn't exist at all -- there is such quantity of broken
-// profiles on black point tag, that we must somehow fix chromaticity to
+// profiles on black point tag, that we must somehow fix chromaticity to
// avoid huge tint when doing Black point compensation. This function does
-// just that. There is a special flag for using black point tag, but turned
-// off by default because it is bogus on most profiles. The detection algorithm
-// involves to turn BP to neutral and to use only L component.
-
+// just that. There is a special flag for using black point tag, but turned
+// off by default because it is bogus on most profiles. The detection algorithm
+// involves to turn BP to neutral and to use only L component.
cmsBool CMSEXPORT cmsDetectBlackPoint(cmsCIEXYZ* BlackPoint, cmsHPROFILE hProfile, cmsUInt32Number Intent, cmsUInt32Number dwFlags)
-{
+{
// Zero for black point
if (cmsGetDeviceClass(hProfile) == cmsSigLinkClass) {
BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
- return FALSE;
+ return FALSE;
}
- // v4 + perceptual & saturation intents does have its own black point, and it is
+ // 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) &&
+ if ((cmsGetEncodedICCversion(hProfile) >= 0x4000000) &&
(Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {
// Matrix shaper share MRC & perceptual intents
- if (cmsIsMatrixShaper(hProfile))
+ 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 -> X = cmsPERCEPTUAL_BLACK_X;
BlackPoint -> Y = cmsPERCEPTUAL_BLACK_Y;
BlackPoint -> Z = cmsPERCEPTUAL_BLACK_Z;
#ifdef CMS_USE_PROFILE_BLACK_POINT_TAG
// v2, v4 rel/abs colorimetric
- if (cmsIsTag(hProfile, cmsSigMediaBlackPointTag) &&
+ if (cmsIsTag(hProfile, cmsSigMediaBlackPointTag) &&
Intent == INTENT_RELATIVE_COLORIMETRIC) {
cmsCIEXYZ *BlackPtr, BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;
cmsCIELab Lab;
- // If black point is specified, then use it,
+ // If black point is specified, then use it,
BlackPtr = cmsReadTag(hProfile, cmsSigMediaBlackPointTag);
if (BlackPtr != NULL) {
if (BlackPoint != NULL)
*BlackPoint = TrustedBlackPoint;
-
+
return TRUE;
}
}
#endif
- // That is about v2 profiles.
+ // That is about v2 profiles.
// If output profile, discount ink-limiting and that's all
- if (Intent == INTENT_RELATIVE_COLORIMETRIC &&
+ if (Intent == INTENT_RELATIVE_COLORIMETRIC &&
(cmsGetDeviceClass(hProfile) == cmsSigOutputClass) &&
(cmsGetColorSpace(hProfile) == cmsSigCmykData))
return BlackPointUsingPerceptualBlack(BlackPoint, hProfile);
}
+
+// ---------------------------------------------------------------------------------------------------------
+
+// Least Squares Fit of a Quadratic Curve to Data
+// http://www.personal.psu.edu/jhm/f90/lectures/lsq2.html
+
+static
+cmsFloat64Number RootOfLeastSquaresFitQuadraticCurve(int n, cmsFloat64Number x[], cmsFloat64Number y[])
+{
+ double sum_x = 0, sum_x2 = 0, sum_x3 = 0, sum_x4 = 0;
+ double sum_y = 0, sum_yx = 0, sum_yx2 = 0;
+ double disc;
+ int i;
+ cmsMAT3 m;
+ cmsVEC3 v, res;
+
+ if (n < 4) return 0;
+
+ for (i=0; i < n; i++) {
+
+ double xn = x[i];
+ double yn = y[i];
+
+ sum_x += xn;
+ sum_x2 += xn*xn;
+ sum_x3 += xn*xn*xn;
+ sum_x4 += xn*xn*xn*xn;
+
+ sum_y += yn;
+ sum_yx += yn*xn;
+ sum_yx2 += yn*xn*xn;
+ }
+
+ _cmsVEC3init(&m.v[0], n, sum_x, sum_x2);
+ _cmsVEC3init(&m.v[1], sum_x, sum_x2, sum_x3);
+ _cmsVEC3init(&m.v[2], sum_x2, sum_x3, sum_x4);
+
+ _cmsVEC3init(&v, sum_y, sum_yx, sum_yx2);
+
+ if (!_cmsMAT3solve(&res, &m, &v)) return 0;
+
+ // y = t x2 + u x + c
+ // x = ( - u + Sqrt( u^2 - 4 t c ) ) / ( 2 t )
+ disc = res.n[1]*res.n[1] - 4.0 * res.n[0] * res.n[2];
+ if (disc < 0) return -1;
+
+ return ( -1.0 * res.n[1] + sqrt( disc )) / (2.0 * res.n[0]);
+}
+
+static
+cmsBool IsMonotonic(int n, const cmsFloat64Number Table[])
+{
+ int i;
+ cmsFloat64Number last;
+
+ last = Table[n-1];
+
+ for (i = n-2; i >= 0; --i) {
+
+ if (Table[i] > last)
+
+ return FALSE;
+ else
+ last = Table[i];
+
+ }
+
+ 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 = RootOfLeastSquaresFitQuadraticCurve(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;
+}
projects / platform / upstream / lcms2.git / blobdiff