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*/
// This file is available under and governed by the GNU General Public // License version 2 only, as published by the Free Software Foundation. // However, the following notice accompanied the original version of this // file: // //--------------------------------------------------------------------------------- // // Little Color Management System // Copyright (c) 1998-2022 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 // is furnished to do so, subject to the following conditions: // // 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 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. // //--------------------------------------------------------------------------------- //
// For correlated color temperature (T) between 4000K and 7000K:
if (T >= 4000. && T <= 7000.)
{
x = -4.6070*(1E9/T3) + 2.9678*(1E6/T2) + 0.09911*(1E3/T) + 0.244063;
} else // or for correlated color temperature (T) between 7000K and 25000K:
if (T > 7000.0 && T <= 25000.0)
{
x = -2.0064*(1E9/T3) + 1.9018*(1E6/T2) + 0.24748*(1E3/T) + 0.237040;
} else {
cmsSignalError(0, cmsERROR_RANGE, "cmsWhitePointFromTemp: invalid temp"); returnFALSE;
}
// Obtain y(x)
y = -3.000*(x*x) + 2.870*x - 0.275;
// wave factors (not used, but here for futures extensions)
WhitePoint -> x = x;
WhitePoint -> y = y;
WhitePoint -> Y = 1.0;
returnTRUE;
}
typedefstruct {
cmsFloat64Number mirek; // temp (in microreciprocal kelvin)
cmsFloat64Number ut; // u coord of intersection w/ blackbody locus
cmsFloat64Number vt; // v coord of intersection w/ blackbody locus
cmsFloat64Number tt; // slope of ISOTEMPERATURE. line
// Same as anterior, but assuming D50 destination. White point is given in xyY static
cmsBool _cmsAdaptMatrixToD50(cmsMAT3* r, const cmsCIExyY* SourceWhitePt)
{
cmsCIEXYZ Dn;
cmsMAT3 Bradford;
cmsMAT3 Tmp;
cmsxyY2XYZ(&Dn, SourceWhitePt);
if (!_cmsAdaptationMatrix(&Bradford, NULL, &Dn, cmsD50_XYZ())) returnFALSE;
Tmp = *r;
_cmsMAT3per(r, &Bradford, &Tmp);
returnTRUE;
}
// 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 assuming that the gamma correction // has transitive property in the transformation chain. // // the algorithm: // // - 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 coefficients of the transformation // - Then, I apply these coefficients 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;
// 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);
}
// Adapts a color to a given illuminant. Original color is expected to have // a SourceWhitePt white point.
cmsBool CMSEXPORT cmsAdaptToIlluminant(cmsCIEXYZ* Result, const cmsCIEXYZ* SourceWhitePt, const cmsCIEXYZ* Illuminant, const cmsCIEXYZ* Value)
{
cmsMAT3 Bradford;
cmsVEC3 In, Out;
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