public double Distance(Lab lab1, Lab lab2)
{
var deltaL = lab1.X - lab2.X;
var deltaA = lab1.Y - lab2.Y;
var deltaB = lab1.Z - lab2.Z;
var c1 = Math.Sqrt(lab1.Y * lab1.Y + lab1.Z * lab1.Z);
var c2 = Math.Sqrt(lab2.Y * lab2.Y + lab2.Z * lab2.Z);
var deltaC = c1 - c2;
var deltaH = deltaA * deltaA + deltaB * deltaB - deltaC * deltaC;
deltaH = deltaH < 0 ? 0 : Math.Sqrt(deltaH);
const double sl = 1.0;
const double kc = 1.0;
const double kh = 1.0;
var sc = 1.0 + K1 * c1;
var sh = 1.0 + K2 * c1;
var deltaLKlsl = deltaL / (Kl * sl);
var deltaCkcsc = deltaC / (kc * sc);
var deltaHkhsh = deltaH / (kh * sh);
var i = deltaLKlsl * deltaLKlsl + deltaCkcsc * deltaCkcsc + deltaHkhsh * deltaHkhsh;
return(i < 0 ? 0 : Math.Sqrt(i));
}
public double Distance(Lab lab1, Lab lab2)
{
var deltaL = lab1.X - lab2.X;
var h = Math.Atan2(lab1.Z, lab1.Y);
var c1 = Math.Sqrt(lab1.Y * lab1.Y + lab1.Z * lab1.Z);
var c2 = Math.Sqrt(lab2.Y * lab2.Y + lab2.Z * lab2.Z);
var deltaC = c1 - c2;
var deltaH = Math.Sqrt(
(lab1.Y - lab2.Y) * (lab1.Y - lab2.Y) +
(lab1.Z - lab2.Z) * (lab1.Z - lab2.Z) -
deltaC * deltaC);
var c1_4 = c1 * c1;
c1_4 *= c1_4;
var t = 164 <= h || h >= 345
? .56 + Math.Abs(.2 * Math.Cos(h + 168.0))
: .36 + Math.Abs(.4 * Math.Cos(h + 35.0));
var f = Math.Sqrt(c1_4 / (c1_4 + 1900.0));
var sL = lab1.X < 16 ? .511 : (.040975 * lab1.X) / (1.0 + .01765 * lab1.X);
var sC = (.0638 * c1) / (1 + .0131 * c1) + .638;
var sH = sC * (f * t + 1 - f);
var differences = DistanceDivided(deltaL, _lightness * sL) +
DistanceDivided(deltaC, _chroma * sC) +
DistanceDivided(deltaH, sH);
return(Math.Sqrt(differences));
}
public double Distance(Lab lab1, Lab lab2)
{
//Set weighting factors to 1
double k_L = 1.0d;
double k_C = 1.0d;
double k_H = 1.0d;
//Change Color Space to L*a*b:
//DateTime t1 = DateTime.Now;
// MessageBox.Show("" + (DateTime.Now.Ticks - t1.Ticks));
//Calculate Cprime1, Cprime2, Cabbar
double c_star_1_ab = Math.Sqrt(lab1.Y * lab1.Y + lab1.Z * lab1.Z);
double c_star_2_ab = Math.Sqrt(lab2.Y * lab2.Y + lab2.Z * lab2.Z);
double c_star_average_ab = (c_star_1_ab + c_star_2_ab) / 2;
double c_star_average_ab_pot7 = c_star_average_ab * c_star_average_ab * c_star_average_ab;
c_star_average_ab_pot7 *= c_star_average_ab_pot7 * c_star_average_ab;
double G = 0.5 * (1 - Math.Sqrt(c_star_average_ab_pot7 / (c_star_average_ab_pot7 + 6103515625))); //25^7
double a1_prime = (1 + G) * lab1.Y;
double a2_prime = (1 + G) * lab2.Y;
double C_prime_1 = Math.Sqrt(a1_prime * a1_prime + lab1.Z * lab1.Z);
double C_prime_2 = Math.Sqrt(a2_prime * a2_prime + lab2.Z * lab2.Z);
//Angles in Degree.
double h_prime_1 = ((Math.Atan2(lab1.Z, a1_prime) * 180d / Math.PI) + 360) % 360d;
double h_prime_2 = ((Math.Atan2(lab2.Z, a2_prime) * 180d / Math.PI) + 360) % 360d;
double delta_L_prime = lab2.X - lab1.X;
double delta_C_prime = C_prime_2 - C_prime_1;
double h_bar = Math.Abs(h_prime_1 - h_prime_2);
double delta_h_prime;
if (C_prime_1 * C_prime_2 == 0)
{
delta_h_prime = 0;
}
else
{
if (h_bar <= 180d)
{
delta_h_prime = h_prime_2 - h_prime_1;
}
else if (h_bar > 180d && h_prime_2 <= h_prime_1)
{
delta_h_prime = h_prime_2 - h_prime_1 + 360.0;
}
else
{
delta_h_prime = h_prime_2 - h_prime_1 - 360.0;
}
}
double delta_H_prime = 2 * Math.Sqrt(C_prime_1 * C_prime_2) * Math.Sin(delta_h_prime * Math.PI / 360);
// Calculate CIEDE2000
double L_prime_average = (lab1.X + lab2.X) / 2d;
double C_prime_average = (C_prime_1 + C_prime_2) / 2d;
//Calculate h_prime_average
double h_prime_average;
if (C_prime_1 * C_prime_2 == 0)
{
h_prime_average = 0;
}
else
{
if (h_bar <= 180d)
{
h_prime_average = (h_prime_1 + h_prime_2) / 2;
}
else if (h_bar > 180d && (h_prime_1 + h_prime_2) < 360d)
{
h_prime_average = (h_prime_1 + h_prime_2 + 360d) / 2;
}
else
{
h_prime_average = (h_prime_1 + h_prime_2 - 360d) / 2;
}
}
double L_prime_average_minus_50_square = (L_prime_average - 50);
L_prime_average_minus_50_square *= L_prime_average_minus_50_square;
double S_L = 1 + ((.015d * L_prime_average_minus_50_square) / Math.Sqrt(20 + L_prime_average_minus_50_square));
double S_C = 1 + .045 * C_prime_average;
double T = 1
- .17 * Math.Cos(DegToRad(h_prime_average - 30))
+ .24 * Math.Cos(DegToRad(h_prime_average * 2))
+ .32 * Math.Cos(DegToRad(h_prime_average * 3 + 6))
- .2 * Math.Cos(DegToRad(h_prime_average * 4 - 63));
double S_H = 1 + .015 * T * C_prime_average;
double h_prime_average_minus_275_div_25_square = (h_prime_average - 275) / (25);
h_prime_average_minus_275_div_25_square *= h_prime_average_minus_275_div_25_square;
double delta_theta = 30 * Math.Exp(-h_prime_average_minus_275_div_25_square);
double C_prime_average_pot_7 = C_prime_average * C_prime_average * C_prime_average;
C_prime_average_pot_7 *= C_prime_average_pot_7 * C_prime_average;
double R_C = 2 * Math.Sqrt(C_prime_average_pot_7 / (C_prime_average_pot_7 + 6103515625));
double R_T = -Math.Sin(DegToRad(2 * delta_theta)) * R_C;
double delta_L_prime_div_k_L_S_L = delta_L_prime / (S_L * k_L);
double delta_C_prime_div_k_C_S_C = delta_C_prime / (S_C * k_C);
double delta_H_prime_div_k_H_S_H = delta_H_prime / (S_H * k_H);
double CIEDE2000 = Math.Sqrt(
delta_L_prime_div_k_L_S_L * delta_L_prime_div_k_L_S_L
+ delta_C_prime_div_k_C_S_C * delta_C_prime_div_k_C_S_C
+ delta_H_prime_div_k_H_S_H * delta_H_prime_div_k_H_S_H
+ R_T * delta_C_prime_div_k_C_S_C * delta_H_prime_div_k_H_S_H
);
return(CIEDE2000);
}
public double Distance(Lab lab1, Lab lab2)
{
var differences = Distance(lab1.X, lab2.X) + Distance(lab1.Y, lab2.Y) + Distance(lab1.Z, lab2.Z);
return(Math.Sqrt(differences));
}
