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libkwineffects/colorspace: apply chromatic adaption

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This commit is contained in:
Xaver Hugl 2023-10-06 12:27:42 +02:00
parent 1e4701309f
commit b200a3180f
2 changed files with 56 additions and 1 deletions
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55
src/libkwineffects/colorspace.cpp
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@ -70,9 +70,62 @@ QMatrix3x3 Colorimetry::toXYZ() const
return matrixFromColumns(r_xyz * component_scale.x(), g_xyz * component_scale.y(), b_xyz * component_scale.z());
}
QMatrix3x3 Colorimetry::chromaticAdaptationMatrix(QVector2D sourceWhitepoint, QVector2D destinationWhitepoint)
{
static const QMatrix3x3 bradford = []() {
QMatrix3x3 ret;
ret(0, 0) = 0.8951;
ret(0, 1) = 0.2664;
ret(0, 2) = -0.1614;
ret(1, 0) = -0.7502;
ret(1, 1) = 1.7135;
ret(1, 2) = 0.0367;
ret(2, 0) = 0.0389;
ret(2, 1) = -0.0685;
ret(2, 2) = 1.0296;
return ret;
}();
static const QMatrix3x3 inverseBradford = []() {
QMatrix3x3 ret;
ret(0, 0) = 0.9869929;
ret(0, 1) = -0.1470543;
ret(0, 2) = 0.1599627;
ret(1, 0) = 0.4323053;
ret(1, 1) = 0.5183603;
ret(1, 2) = 0.0492912;
ret(2, 0) = -0.0085287;
ret(2, 1) = 0.0400428;
ret(2, 2) = 0.9684867;
return ret;
}();
const QVector3D factors = (bradford * xyToXYZ(destinationWhitepoint)) / (bradford * xyToXYZ(sourceWhitepoint));
QMatrix3x3 adaptation{};
adaptation(0, 0) = factors.x();
adaptation(1, 1) = factors.y();
adaptation(2, 2) = factors.z();
return inverseBradford * adaptation * bradford;
}
QMatrix3x3 Colorimetry::toOther(const Colorimetry &other) const
{
return toXYZ() * inverse(other.toXYZ());
// rendering intent is relative colorimetric, so adapt to the different whitepoint
if (white == other.white) {
return inverse(other.toXYZ()) * toXYZ();
} else {
return inverse(other.toXYZ()) * chromaticAdaptationMatrix(this->white, other.white) * toXYZ();
}
}
Colorimetry Colorimetry::adaptedTo(QVector2D newWhitepoint) const
{
const auto mat = chromaticAdaptationMatrix(this->white, newWhitepoint);
return Colorimetry{
.red = xyzToXY(mat * xyToXYZ(red)),
.green = xyzToXY(mat * xyToXYZ(green)),
.blue = xyzToXY(mat * xyToXYZ(blue)),
.white = newWhitepoint,
.name = std::nullopt,
};
}
bool Colorimetry::operator==(const Colorimetry &other) const

2
src/libkwineffects/colorspace.h
View file

@ -31,10 +31,12 @@ public:
static Colorimetry fromXYZ(QVector3D red, QVector3D green, QVector3D blue, QVector3D white);
static QVector3D xyToXYZ(QVector2D xy);
static QVector2D xyzToXY(QVector3D xyz);
static QMatrix3x3 chromaticAdaptationMatrix(QVector2D sourceWhitepoint, QVector2D destinationWhitepoint);
QMatrix3x3 toXYZ() const;
QMatrix3x3 toOther(const Colorimetry &colorimetry) const;
bool operator==(const Colorimetry &other) const;
Colorimetry adaptedTo(QVector2D newWhitepoint) const;
QVector2D red;
QVector2D green;