/**
* Create viewing conditions assuming full adaption. This is primarily useful in color management
* applications.
*
* @param XYZ_w XYZ of adopted whitepoint
* @param L_A average luminance of visual surround
* @param Y_b adaptation luminance of color background
* @param sur the surrounding
* @return a fully adapted viewing conditions instance
*/
public static ViewingConditions createFullyAdapted(
CIEXYZ XYZ_w, float L_A, float Y_b, Surrounding sur) {
double[] xyz_w = MathTools.floatToDoubleArray(XYZ_w.toCIEXYZ100());
double[] RGB_w = CS_CIECAM02.XYZtoCAT02(xyz_w);
double[] RGB_c = calcAdaptedRGBc(XYZ_w, RGB_w, 1.0);
return new ViewingConditions(xyz_w, L_A, Y_b, sur, RGB_w, RGB_c);
}
private static double[] calcAdaptedRGBc(CIEXYZ XYZ_w, double[] RGB_w, double D) {
double[] RGB_c = new double[3];
double Yw = XYZ_w.get(CIEXYZ.Y) * 100;
for (int i = 0; i < RGB_c.length; i++) {
RGB_c[i] = (D * Yw / RGB_w[i]) + (1.0 - D);
}
return RGB_c;
}
/**
* Construct a new ViewingConditions instance. The degree of adaption (D) is derived from the
* background and surround. This is the standard case treated in CIE 159:2004.
*
* @param XYZ_w XYZ of adopted whitepoint
* @param L_A average luminance of visual surround
* @param Y_b adaptation luminance of color background
* @param sur the surrounding
* @return a ViewingConditions instance
*/
public static ViewingConditions createAdapted(
CIEXYZ XYZ_w, double L_A, double Y_b, Surrounding sur) {
double[] xyz_w = MathTools.floatToDoubleArray(XYZ_w.toCIEXYZ100());
// calculate RGB whitepoint
double[] RGB_w = CS_CIECAM02.XYZtoCAT02(xyz_w);
double D = calcD(L_A, sur);
double[] RGB_c = calcAdaptedRGBc(XYZ_w, RGB_w, D);
return new ViewingConditions(xyz_w, L_A, Y_b, sur, RGB_w, RGB_c);
}
/**
* Derive (or better: guess) an (adopted) white point by mixing two white points. Luminance will
* also be mixed. See CIE:159:2004, section 5.
*
* @param background_white the whitepoint of the background
* @param surround_white the whitepoint of the surround
* @param bgFactor the background weight
* @return XYZ mixed from background and surround
*/
public static CIEXYZ mixedWhitepoint(
CIEXYZ background_white, CIEXYZ surround_white, float bgFactor) {
return CIEXYZ.blend(
new CIEXYZ[] {background_white, surround_white}, new float[] {bgFactor, 1 - bgFactor});
}
