internal static void XYZtoDKL(Color1931XYZ stimulus, ColorLMS backgroundLMS, ref ColorTransformMatrix XYZtoLMS, ref ColorTransformMatrix LMStoDKL, out ColorDKL dkl)
{
ColorLMS stimulusLMS;
XYZtoLMS.Transform(stimulus.X, stimulus.Y, stimulus.Z, out stimulusLMS.L, out stimulusLMS.M, out stimulusLMS.S);
ColorLMS deltaLMS = stimulusLMS - backgroundLMS;
LMStoDKL.Transform(deltaLMS.L, deltaLMS.M, deltaLMS.S, out dkl.Isochromatic, out dkl.RGisoluminant, out dkl.Sisoluminant);
}
internal static void DKLtoXYZ(ColorDKL dkl, ColorLMS backgroundLMS, ref ColorTransformMatrix DKLtoLMS, ref ColorTransformMatrix LMStoXYZ, out Color1931XYZ xyz)
{
ColorLMS diffLMS;
DKLtoLMS.Transform(dkl.Isochromatic, dkl.RGisoluminant, dkl.Sisoluminant, out diffLMS.L, out diffLMS.M, out diffLMS.S);
ColorLMS stimulusLMS = diffLMS + backgroundLMS;
LMStoXYZ.Transform(stimulusLMS.L, stimulusLMS.M, stimulusLMS.S, out xyz.X, out xyz.Y, out xyz.Z);
}
// Kaiser, Bonton (1996). Human Color Vision (Second Edition), Appendix, Part IV
public static ColorTransformMatrix GetScaledLMStoDKL(ColorLMS background)
{
ColorTransformMatrix LMStoDKL = new ColorTransformMatrix
(
1, 1, 0,
1, -background.L / background.M, 0,
-1, -1, (background.L + background.M) / background.S
);
ColorTransformMatrix DKLtoLMS = LMStoDKL.Invert();
ColorLMS isolatingIso = new ColorLMS(DKLtoLMS.a, DKLtoLMS.d, DKLtoLMS.g);
float pooledConeContrastIso = (isolatingIso / background).Length;
ColorLMS normalizedIso = isolatingIso / pooledConeContrastIso;
ColorLMS isolatingRGiso = new ColorLMS(DKLtoLMS.b, DKLtoLMS.e, DKLtoLMS.h);
float pooledConeCotnrastRGiso = (isolatingRGiso / background).Length;
ColorLMS normalizedRGiso = isolatingRGiso / pooledConeCotnrastRGiso;
ColorLMS isolatingSiso = new ColorLMS(DKLtoLMS.c, DKLtoLMS.f, DKLtoLMS.i);
float pooledConeContrastSiso = (isolatingSiso / background).Length;
ColorLMS normalizedSiso = isolatingSiso / pooledConeContrastSiso;
ColorDKL unitResponse;
LMStoDKL.Transform(normalizedIso.L, normalizedIso.M, normalizedIso.S, out unitResponse.Isochromatic, out _, out _);
LMStoDKL.Transform(normalizedRGiso.L, normalizedRGiso.M, normalizedRGiso.S, out _, out unitResponse.RGisoluminant, out _);
LMStoDKL.Transform(normalizedSiso.L, normalizedSiso.M, normalizedSiso.S, out _, out _, out unitResponse.Sisoluminant);
ColorTransformMatrix rescaler = new ColorTransformMatrix
(
1 / unitResponse.Isochromatic, 0, 0,
0, 1 / unitResponse.RGisoluminant, 0,
0, 0, 1 / unitResponse.Sisoluminant
);
return(rescaler * LMStoDKL);
}