public static Color ShiftLightness(this Color color, int amount = 1)
{
var lab = color.ToLab();
var shifted = new Lab(lab.L - LabConstants.Kn * amount, lab.A, lab.B);
return(shifted.ToColor());
}
/// <summary>
/// Calculates the CIE76 distance between two colors.
/// </summary>
/// <param name="color"></param>
/// <param name="other"></param>
/// <returns></returns>
public static double Difference(this Color color, Color other)
{
Lab lab1 = color.ToLab();
Lab lab2 = color.ToLab();
return(Math.Sqrt(Math.Pow(lab2.L - lab1.L, 2) +
Math.Pow(lab2.A - lab1.A, 2) +
Math.Pow(lab2.B - lab1.B, 2)));
}
public static Xyz ToXyz(this Lab lab)
{
double lab_xyz(double d)
{
if (d > LabConstants.eCubedRoot)
{
return(d * d * d);
}
else
{
return((116 * d - 16) / LabConstants.k);
}
}
var y = (lab.L + 16.0) / 116.0;
var x = double.IsNaN(lab.A) ? y : y + lab.A / 500.0;
var z = double.IsNaN(lab.B) ? y : y - lab.B / 200.0;
y = LabConstants.WhitePointY * lab_xyz(y);
x = LabConstants.WhitePointX * lab_xyz(x);
z = LabConstants.WhitePointZ * lab_xyz(z);
return(new Xyz(x, y, z));
}
public static Color ToColor(this Lab lab)
{
var xyz = lab.ToXyz();
return(xyz.ToColor());
}