// Approximate a blackbody illuminant based on CHAD information
static
cmsFloat64Number CHAD2Temp(const cmsMAT3* Chad)
{
// Convert D50 across inverse CHAD to get the absolute white point
cmsVEC3 d, s;
cmsCIEXYZ Dest;
cmsCIExyY DestChromaticity;
cmsFloat64Number TempK;
cmsMAT3 m1, m2;
m1 = *Chad;
if (!_cmsMAT3inverse(&m1, &m2)) return FALSE;
s.n[VX] = cmsD50_XYZ() -> X;
s.n[VY] = cmsD50_XYZ() -> Y;
s.n[VZ] = cmsD50_XYZ() -> Z;
_cmsMAT3eval(&d, &m2, &s);
Dest.X = d.n[VX];
Dest.Y = d.n[VY];
Dest.Z = d.n[VZ];
cmsXYZ2xyY(&DestChromaticity, &Dest);
if (!cmsTempFromWhitePoint(&TempK, &DestChromaticity))
return -1.0;
return TempK;
}
static
cmsPipeline* BuildRGBOutputMatrixShaper(cmsHPROFILE hProfile)
{
cmsPipeline* Lut;
cmsToneCurve *Shapes[3], *InvShapes[3];
cmsMAT3 Mat, Inv;
int i, j;
cmsContext ContextID = cmsGetProfileContextID(hProfile);
if (!ReadICCMatrixRGB2XYZ(&Mat, hProfile))
return NULL;
if (!_cmsMAT3inverse(&Mat, &Inv))
return NULL;
// XYZ PCS in encoded in 1.15 format, and the matrix input should come in 0..0xffff range, so
// we need to adjust the input by a << 1 to obtain a 1.16 fixed and then by a factor of
// (0xffff/0x10000) to put data in 0..0xffff range. Total factor is (2.0*65535.0)/65536.0;
for (i=0; i < 3; i++)
for (j=0; j < 3; j++)
Inv.v[i].n[j] *= OutpAdj;
Shapes[0] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigRedTRCTag);
Shapes[1] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigGreenTRCTag);
Shapes[2] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigBlueTRCTag);
if (!Shapes[0] || !Shapes[1] || !Shapes[2])
return NULL;
InvShapes[0] = cmsReverseToneCurve(Shapes[0]);
InvShapes[1] = cmsReverseToneCurve(Shapes[1]);
InvShapes[2] = cmsReverseToneCurve(Shapes[2]);
if (!InvShapes[0] || !InvShapes[1] || !InvShapes[2]) {
return NULL;
}
Lut = cmsPipelineAlloc(ContextID, 3, 3);
if (Lut != NULL) {
// Note that it is certainly possible a single profile would have a LUT based
// tag for output working in lab and a matrix-shaper for the fallback cases.
// This is not allowed by the spec, but this code is tolerant to those cases
if (cmsGetPCS(hProfile) == cmsSigLabData) {
cmsPipelineInsertStage(Lut, cmsAT_END, _cmsStageAllocLab2XYZ(ContextID));
}
cmsPipelineInsertStage(Lut, cmsAT_END, cmsStageAllocMatrix(ContextID, 3, 3, (cmsFloat64Number*) &Inv, NULL));
cmsPipelineInsertStage(Lut, cmsAT_END, cmsStageAllocToneCurves(ContextID, 3, InvShapes));
}
cmsFreeToneCurveTriple(InvShapes);
return Lut;
}
// Solve a system in the form Ax = b
cmsBool CMSEXPORT _cmsMAT3solve(cmsVEC3* x, cmsMAT3* a, cmsVEC3* b)
{
cmsMAT3 m, a_1;
memmove(&m, a, sizeof(cmsMAT3));
if (!_cmsMAT3inverse(&m, &a_1)) return FALSE; // Singular matrix
_cmsMAT3eval(x, &a_1, b);
return TRUE;
}
static
cmsPipeline* BuildRGBOutputMatrixShaper(cmsHPROFILE hProfile)
{
cmsPipeline* Lut;
cmsToneCurve *Shapes[3], *InvShapes[3];
cmsMAT3 Mat, Inv;
int i, j;
cmsContext ContextID = cmsGetProfileContextID(hProfile);
if (!ReadICCMatrixRGB2XYZ(&Mat, hProfile))
return NULL;
if (!_cmsMAT3inverse(&Mat, &Inv))
return NULL;
// XYZ PCS in encoded in 1.15 format, and the matrix input should come in 0..0xffff range, so
// we need to adjust the input by a << 1 to obtain a 1.16 fixed and then by a factor of
// (0xffff/0x10000) to put data in 0..0xffff range. Total factor is (2.0*65535.0)/65536.0;
for (i=0; i < 3; i++)
for (j=0; j < 3; j++)
Inv.v[i].n[j] *= OutpAdj;
Shapes[0] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigRedTRCTag);
Shapes[1] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigGreenTRCTag);
Shapes[2] = (cmsToneCurve *) cmsReadTag(hProfile, cmsSigBlueTRCTag);
if (!Shapes[0] || !Shapes[1] || !Shapes[2])
return NULL;
InvShapes[0] = cmsReverseToneCurve(Shapes[0]);
InvShapes[1] = cmsReverseToneCurve(Shapes[1]);
InvShapes[2] = cmsReverseToneCurve(Shapes[2]);
if (!InvShapes[0] || !InvShapes[1] || !InvShapes[2]) {
return NULL;
}
Lut = cmsPipelineAlloc(ContextID, 3, 3);
if (Lut != NULL) {
cmsPipelineInsertStage(Lut, cmsAT_END, cmsStageAllocMatrix(ContextID, 3, 3, (cmsFloat64Number*) &Inv, NULL));
cmsStage* mpe = cmsStageAllocToneCurves(ContextID, 3, InvShapes);
if (mpe)
cmsPipelineInsertStage(Lut, cmsAT_END, mpe);
else {
cmsPipelineFree(Lut);
Lut = NULL;
}
}
cmsFreeToneCurveTriple(InvShapes);
return Lut;
}
// Build a White point, primary chromas transfer matrix from RGB to CIE XYZ
// This is just an approximation, I am not handling all the non-linear
// aspects of the RGB to XYZ process, and assumming that the gamma correction
// has transitive property in the transformation chain.
//
// the alghoritm:
//
// - First I build the absolute conversion matrix using
// primaries in XYZ. This matrix is next inverted
// - Then I eval the source white point across this matrix
// obtaining the coeficients of the transformation
// - Then, I apply these coeficients to the original matrix
//
cmsBool _cmsBuildRGB2XYZtransferMatrix(cmsMAT3* r, const cmsCIExyY* WhitePt, const cmsCIExyYTRIPLE* Primrs)
{
cmsVEC3 WhitePoint, Coef;
cmsMAT3 Result, Primaries;
cmsFloat64Number xn, yn;
cmsFloat64Number xr, yr;
cmsFloat64Number xg, yg;
cmsFloat64Number xb, yb;
xn = WhitePt -> x;
yn = WhitePt -> y;
xr = Primrs -> Red.x;
yr = Primrs -> Red.y;
xg = Primrs -> Green.x;
yg = Primrs -> Green.y;
xb = Primrs -> Blue.x;
yb = Primrs -> Blue.y;
// Build Primaries matrix
_cmsVEC3init(&Primaries.v[0], xr, xg, xb);
_cmsVEC3init(&Primaries.v[1], yr, yg, yb);
_cmsVEC3init(&Primaries.v[2], (1-xr-yr), (1-xg-yg), (1-xb-yb));
// Result = Primaries ^ (-1) inverse matrix
if (!_cmsMAT3inverse(&Primaries, &Result))
return FALSE;
_cmsVEC3init(&WhitePoint, xn/yn, 1.0, (1.0-xn-yn)/yn);
// Across inverse primaries ...
_cmsMAT3eval(&Coef, &Result, &WhitePoint);
// Give us the Coefs, then I build transformation matrix
_cmsVEC3init(&r -> v[0], Coef.n[VX]*xr, Coef.n[VY]*xg, Coef.n[VZ]*xb);
_cmsVEC3init(&r -> v[1], Coef.n[VX]*yr, Coef.n[VY]*yg, Coef.n[VZ]*yb);
_cmsVEC3init(&r -> v[2], Coef.n[VX]*(1.0-xr-yr), Coef.n[VY]*(1.0-xg-yg), Coef.n[VZ]*(1.0-xb-yb));
return _cmsAdaptMatrixToD50(r, WhitePt);
}
static
cmsBool ComputeChromaticAdaptation(cmsMAT3* Conversion,
const cmsCIEXYZ* SourceWhitePoint,
const cmsCIEXYZ* DestWhitePoint,
const cmsMAT3* Chad)
{
cmsMAT3 Chad_Inv;
cmsVEC3 ConeSourceXYZ, ConeSourceRGB;
cmsVEC3 ConeDestXYZ, ConeDestRGB;
cmsMAT3 Cone, Tmp;
Tmp = *Chad;
if (!_cmsMAT3inverse(&Tmp, &Chad_Inv)) return FALSE;
_cmsVEC3init(&ConeSourceXYZ, SourceWhitePoint -> X,
SourceWhitePoint -> Y,
SourceWhitePoint -> Z);
_cmsVEC3init(&ConeDestXYZ, DestWhitePoint -> X,
DestWhitePoint -> Y,
DestWhitePoint -> Z);
_cmsMAT3eval(&ConeSourceRGB, Chad, &ConeSourceXYZ);
_cmsMAT3eval(&ConeDestRGB, Chad, &ConeDestXYZ);
// Build matrix
_cmsVEC3init(&Cone.v[0], ConeDestRGB.n[0]/ConeSourceRGB.n[0], 0.0, 0.0);
_cmsVEC3init(&Cone.v[1], 0.0, ConeDestRGB.n[1]/ConeSourceRGB.n[1], 0.0);
_cmsVEC3init(&Cone.v[2], 0.0, 0.0, ConeDestRGB.n[2]/ConeSourceRGB.n[2]);
// Normalize
_cmsMAT3per(&Tmp, &Cone, Chad);
_cmsMAT3per(Conversion, &Chad_Inv, &Tmp);
return TRUE;
}
// Join scalings to obtain relative input to absolute and then to relative output.
// Result is stored in a 3x3 matrix
static
cmsBool ComputeAbsoluteIntent(cmsFloat64Number AdaptationState,
const cmsCIEXYZ* WhitePointIn,
const cmsMAT3* ChromaticAdaptationMatrixIn,
const cmsCIEXYZ* WhitePointOut,
const cmsMAT3* ChromaticAdaptationMatrixOut,
cmsMAT3* m)
{
cmsMAT3 Scale, m1, m2, m3, m4;
// Adaptation state
if (AdaptationState == 1.0) {
// Observer is fully adapted. Keep chromatic adaptation.
// That is the standard V4 behaviour
_cmsVEC3init(&m->v[0], WhitePointIn->X / WhitePointOut->X, 0, 0);
_cmsVEC3init(&m->v[1], 0, WhitePointIn->Y / WhitePointOut->Y, 0);
_cmsVEC3init(&m->v[2], 0, 0, WhitePointIn->Z / WhitePointOut->Z);
}
else {
// Incomplete adaptation. This is an advanced feature.
_cmsVEC3init(&Scale.v[0], WhitePointIn->X / WhitePointOut->X, 0, 0);
_cmsVEC3init(&Scale.v[1], 0, WhitePointIn->Y / WhitePointOut->Y, 0);
_cmsVEC3init(&Scale.v[2], 0, 0, WhitePointIn->Z / WhitePointOut->Z);
if (AdaptationState == 0.0) {
m1 = *ChromaticAdaptationMatrixOut;
_cmsMAT3per(&m2, &m1, &Scale);
// m2 holds CHAD from output white to D50 times abs. col. scaling
// Observer is not adapted, undo the chromatic adaptation
_cmsMAT3per(m, &m2, ChromaticAdaptationMatrixOut);
m3 = *ChromaticAdaptationMatrixIn;
if (!_cmsMAT3inverse(&m3, &m4)) return FALSE;
_cmsMAT3per(m, &m2, &m4);
} else {
cmsMAT3 MixedCHAD;
cmsFloat64Number TempSrc, TempDest, Temp;
m1 = *ChromaticAdaptationMatrixIn;
if (!_cmsMAT3inverse(&m1, &m2)) return FALSE;
_cmsMAT3per(&m3, &m2, &Scale);
// m3 holds CHAD from input white to D50 times abs. col. scaling
TempSrc = CHAD2Temp(ChromaticAdaptationMatrixIn);
TempDest = CHAD2Temp(ChromaticAdaptationMatrixOut);
if (TempSrc < 0.0 || TempDest < 0.0) return FALSE; // Something went wrong
if (_cmsMAT3isIdentity(&Scale) && fabs(TempSrc - TempDest) < 0.01) {
_cmsMAT3identity(m);
return TRUE;
}
Temp = (1.0 - AdaptationState) * TempDest + AdaptationState * TempSrc;
// Get a CHAD from whatever output temperature to D50. This replaces output CHAD
Temp2CHAD(&MixedCHAD, Temp);
_cmsMAT3per(m, &m3, &MixedCHAD);
}
}
return TRUE;
}
