public static DNGxyCoord XYZtoXY(DNGVector3 coord)
{
double X = coord[0];
double Y = coord[1];
double Z = coord[2];
double total = X + Y + Z;
if (total > 0.0)
{
return(new DNGxyCoord(X / total, Y / total));
}
return(DNGxyCoord.D50);
}
/// Return the XY value to use for SetWhiteXY for a given camera color
/// space coordinate as the white point.
/// \param neutral A camera color space value to use for white point.
/// Components range from 0.0 to 1.0 and should be normalized such that
/// the largest value is 1.0 .
/// \retval White point in XY space that makes neutral map to this
/// XY value as closely as possible.
public DNGxyCoord NeutralToXY(DNGVector neutral)
{
const uint kMaxPasses = 30;
if (fChannels == 1)
{
return(DNGxyCoord.PCStoXY);
}
DNGxyCoord last = DNGxyCoord.D50;
for (uint pass = 0; pass < kMaxPasses; pass++)
{
DNGMatrix nullMat = null;
DNGMatrix xyzToCamera = FindXYZtoCamera(last, ref nullMat, ref nullMat, ref nullMat);
DNGMatrix inv = xyzToCamera.Invert();
DNGVector vec = inv * neutral;
DNGVector3 vec3 = new DNGVector3(vec);
DNGxyCoord next = DNGxyCoord.XYZtoXY(new DNGVector3(xyzToCamera.Invert() * neutral));
if (Math.Abs(next.X - last.X) +
Math.Abs(next.Y - last.Y) < 0.0000001)
{
return(next);
}
// If we reach the limit without converging, we are most likely
// in a two value oscillation. So take the average of the last
// two estimates and give up.
if (pass == kMaxPasses - 1)
{
next.X = (last.X + next.X) * 0.5;
next.Y = (last.Y + next.Y) * 0.5;
}
last = next;
}
return(last);
}
