public ColorRgb(ColorXyz xyz, RgbWorkingSpace ws)
{
var m = ws.XyztoRgbMatrix;
double x = xyz.X / 100;
double y = xyz.Y / 100;
double z = xyz.Z / 100;
double lin_r = (x * m[0, 0]) + (y * m[0, 1]) + (z * m[0, 2]); // red
double lin_g = (x * m[1, 0]) + (y * m[1, 1]) + (z * m[1, 2]); // green
double lin_b = (x * m[2, 0]) + (y * m[2, 1]) + (z * m[2, 2]); // blue
double r = (lin_r <= 0.0031308) ? 12.92 * lin_r : (1.055) * System.Math.Pow(lin_r, (1.0 / 2.4)) - 0.055;
double g = (lin_g <= 0.0031308) ? 12.92 * lin_g : (1.055) * System.Math.Pow(lin_g, (1.0 / 2.4)) - 0.055;
double b = (lin_b <= 0.0031308) ? 12.92 * lin_b : (1.055) * System.Math.Pow(lin_b, (1.0 / 2.4)) - 0.055;
r = ClampToRange_0_1(r);
g = ClampToRange_0_1(g);
b = ClampToRange_0_1(b);
this._alpha = xyz.Alpha;
this._r = r;
this._g = g;
this._b = b;
}
public ColorXyz(double alpha, double x, double y, double z)
{
ColorXyz.check_xyz(alpha, x, y, z);
this._alpha = alpha;
this._x = x;
this._y = y;
this._z = z;
}
public static ColorLab ToLab(ColorRgb rgb)
{
ColorXyz xyz = XyzConverter.ToXyz(rgb);
ColorXyz white = XyzConverter.WhiteReference;
double x = PivotXyz(xyz.X / white.X);
double y = PivotXyz(xyz.Y / white.Y);
double z = PivotXyz(xyz.Z / white.Z);
return(new ColorLab(
Math.Max(0, 116 * y - 16),
500 * (x - y),
200 * (y - z)));
}
public void Colors_ShouldRoundtripFromRgbToCielab()
{
// Arrange
var color = Color.Red;
// Act
var colorRgb = new RgbVector(color);
var colorXyz = ColorXyz.FromRgb(colorRgb);
var colorCielab = ColorCielab.FromRgb(colorRgb);
var colorXyzBack = colorCielab.AsColorXyz();
var colorRgbBack = colorXyzBack.AsColorRgb();
// Assert
Assert.Fail();
}
public static ColorRgb ToColor(ColorLab lab)
{
double y = (lab.L + 16.0) / 116.0;
double x = lab.A / 500.0 + y;
double z = y - lab.B / 200.0;
ColorXyz white = XyzConverter.WhiteReference;
double x3 = x * x * x;
double z3 = z * z * z;
ColorXyz xyz = new ColorXyz(
white.X * (x3 > XyzConverter.Epsilon ? x3 : (x - 16.0 / 116.0) / 7.787),
white.Y * (lab.L > (XyzConverter.Kappa * XyzConverter.Epsilon) ? Math.Pow(((lab.L + 16.0) / 116.0), 3) : lab.L / XyzConverter.Kappa),
white.Z * (z3 > XyzConverter.Epsilon ? z3 : (z - 16.0 / 116.0) / 7.787));
return(XyzConverter.ToColor(xyz));
}
public static ColorRgb ToColor(ColorXyz xyz)
{
// (Observer = 2°, Illuminant = D65)
double x = xyz.X / 100.0;
double y = xyz.Y / 100.0;
double z = xyz.Z / 100.0;
double r = x * 3.2406 + y * -1.5372 + z * -0.4986;
double g = x * -0.9689 + y * 1.8758 + z * 0.0415;
double b = x * 0.0557 + y * -0.2040 + z * 1.0570;
r = r > 0.0031308 ? 1.055 * Math.Pow(r, 1 / 2.4) - 0.055 : 12.92 * r;
g = g > 0.0031308 ? 1.055 * Math.Pow(g, 1 / 2.4) - 0.055 : 12.92 * g;
b = b > 0.0031308 ? 1.055 * Math.Pow(b, 1 / 2.4) - 0.055 : 12.92 * b;
return(new ColorRgb(ToRgb(r), ToRgb(g), ToRgb(b)));
}
public ColorXyz(ColorLab lab, RgbWorkingSpace ws)
{
ColorXyz i = ws.ReferenceWhite.ColorXyz;
double delta = 6.0 / 29.0;
double fy = (lab.L + 16) / 116.0;
double fx = fy + (lab.A / 500.0);
double fz = fy - (lab.B / 200.0);
double x = (fx > delta) ? i.X * (fx * fx * fx) : (fx - 16.0 / 116.0) * 3 * (delta * delta) * i.X;
double y = (fy > delta) ? i.Y * (fy * fy * fy) : (fy - 16.0 / 116.0) * 3 * (delta * delta) * i.Y;
double z = (fz > delta) ? i.Z * (fz * fz * fz) : (fz - 16.0 / 116.0) * 3 * (delta * delta) * i.Z;
this._alpha = lab.Alpha;
this._x = x;
this._y = y;
this._z = z;
}
public Illuminant(string name, int degree, ColorXyz xyz)
{
this.Name = name;
this.Degree = degree;
this.ColorXyz = xyz;
}
