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using System;
using System.Windows.Media;
namespace ColorPicker.ColorModels.Lab
{
class LabModel
{
private const double D65X = 0.9505;
private const double D65Y =1.0;
private const double D65Z = 1.0890;
public Color Color (double l, double a , double b)
{
double theta = 6.0/29.0;
double fy = (l+16)/116.0;
double fx = fy + (a/500.0);
double fz = fy - (b/200.0);
var x = (fx > theta) ? D65X*(fx*fx*fx) : (fx - 16.0/116.0)*3*(theta*theta)*D65X;
var y = (fy > theta) ? D65Y*(fy*fy*fy) : (fy - 16.0/116.0)*3*(theta*theta)*D65Y;
var z = (fz > theta)?D65Z * (fz*fz*fz) : (fz - 16.0/116.0)*3*(theta*theta)*D65Z;
x = (x > 0.9505) ? 0.9505 : ((x < 0) ? 0 : x);
y = (y > 1.0) ? 1.0 : ((y < 0) ? 0 : y);
z = (z > 1.089) ? 1.089 : ((z < 0) ? 0 : z);
double[] Clinear = new double[3];
Clinear[0] = x*3.2410 - y*1.5374 - z*0.4986; // red
Clinear[1] = -x*0.9692 + y*1.8760 - z*0.0416; // green
Clinear[2] = x*0.0556 - y*0.2040 + z*1.0570; // blue
for(int i=0; i<3; i++)
{
Clinear[i] = (Clinear[i]<=0.0031308)? 12.92*Clinear[i] : (1+0.055)* Math.Pow(Clinear[i], (1.0/2.4)) - 0.055;
Clinear[i] = Math.Min(Clinear[i], 1);
Clinear[i] = Math.Max(Clinear[i], 0);
}
return System.Windows.Media.Color.FromRgb(
Convert.ToByte(Clinear[0]*255.0),
Convert.ToByte(Clinear[1]*255.0),
Convert.ToByte(Clinear[2]*255.0));
}
public double LComponent(Color color)
{
// normalize red, green, blue values
double rLinear = color.R / 255.0;
double gLinear = color.G / 255.0;
double bLinear = color.B / 255.0;
double r = (rLinear > 0.04045) ? Math.Pow((rLinear + 0.055) / (1 + 0.055), 2.2) : (rLinear / 12.92);
double g = (gLinear > 0.04045) ? Math.Pow((gLinear + 0.055) / (1 + 0.055), 2.2) : (gLinear / 12.92);
double b = (bLinear > 0.04045) ? Math.Pow((bLinear + 0.055) / (1 + 0.055), 2.2) : (bLinear / 12.92);
double CIEY = r * 0.2126 + g * 0.7152 + b * 0.0722;
double l = 116.0 * Fxyz(CIEY / D65Y) - 16;
return l;
}
public double AComponent(Color color)
{
double rLinear = color.R / 255.0;
double gLinear = color.G / 255.0;
double bLinear = color.B / 255.0;
double r = (rLinear > 0.04045) ? Math.Pow((rLinear + 0.055) / (1 + 0.055), 2.2) : (rLinear / 12.92);
double g = (gLinear > 0.04045) ? Math.Pow((gLinear + 0.055) / (1 + 0.055), 2.2) : (gLinear / 12.92);
double b = (bLinear > 0.04045) ? Math.Pow((bLinear + 0.055) / (1 + 0.055), 2.2) : (bLinear / 12.92);
double CIEX = r * 0.4124 + g * 0.3576 + b * 0.1805;
double CIEY = r * 0.2126 + g * 0.7152 + b * 0.0722;
double a = 500.0 * (Fxyz(CIEX / D65X) - Fxyz(CIEY / D65Y));
return a;
}
public double BComponent(Color color)
{
double rLinear = color.R / 255.0;
double gLinear = color.G / 255.0;
double bLinear = color.B / 255.0;
double r = (rLinear > 0.04045) ? Math.Pow((rLinear + 0.055) / (1 + 0.055), 2.2) : (rLinear / 12.92);
double g = (gLinear > 0.04045) ? Math.Pow((gLinear + 0.055) / (1 + 0.055), 2.2) : (gLinear / 12.92);
double b = (bLinear > 0.04045) ? Math.Pow((bLinear + 0.055) / (1 + 0.055), 2.2) : (bLinear / 12.92);
double CIEY = r * 0.2126 + g * 0.7152 + b * 0.0722;
double CIEZ = r * 0.0193 + g * 0.1192 + b * 0.9505;
return 200.0 * (Fxyz(CIEY / D65Y) - Fxyz(CIEZ / D65Z));
}
private static double Fxyz(double t)
{
return ((t > 0.008856)? Math.Pow(t, (1.0/3.0)) : (7.787*t + 16.0/116.0));
}
}
}
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