/**
* calculate the angle in radians of the point (cieX, cieY) in the CIE chromaticity diagram with
* respect to an origin of (0.35, 0.35). Note that one should check for white before using this as
* the resulting angle will not be a significant answer if it is. The angles are
*
* <pre> 90(=pi/2)
* |
* |
* 180 ----------- 0
* (=pi) |
* |
* 270(=3pi/2)
* </pre>
*
* @param cieX
* @param cieY
* @return the angle in radians of the point (cieX, cieY) with respect to an origin of (0.35,
* 0.35). The invoker should check the original r,g,b for black and white to avoid use here. A
* value of -1 is returned for white.
*/
public double calculateXYTheta(float cieX, float cieY) {
if (cieX == 0.35) {
if (cieY > (0.35 + deltaWhite)) {
return Math.PI / 2.;
} else if (cieY < (0.35 - deltaWhite)) {
return 1.5 * Math.PI;
} else {
// this should have been found as white to avoid use here
return -1;
}
}
double theta = MiscMath.calculatePolarTheta(cieX - 0.35f, cieY - 0.35f);
return theta;
}
