internal class ColorDifferences
{ /// <CIE 1976 L*a*b*色差公式> /// </summary> /// <param name="L1"></param> /// <param name="a1"></param> /// <param name="b1"></param> /// <param name="L2"></param> /// <param name="a2"></param> /// <param name="b2"></param> /// <returns></returns>public static double delta_Eab(double L1, double a1, double b1, double L2, double a2, double b2)
{ double Eab = 0; // △Eab double chafang_L = 0; // (L1-L2)*(L1-L2) double chafang_a = 0; // (a1-a2)*(a1-a2) double chafang_b = 0; // (b1-b2)*(b1-b2)chafang_L = ( L1 - L2 ) * ( L1 - L2 ); //差-方
chafang_a = ( a1 - a2 ) * ( a1 - a2 ); chafang_b = ( b1 - b2 ) * ( b1 - b2 );Eab = Math.Pow(chafang_L + chafang_a + chafang_b, 0.5);
return Eab;
}/// <CIE DE 2000色差公式>
/// </summary> /// <param name="L1"></param> /// <param name="a1"></param> /// <param name="b1"></param> /// <param name="L2"></param> /// <param name="a2"></param> /// <param name="b2"></param> /// <returns></returns>public static double delta_E00(double L1, double a1, double b1, double L2, double a2, double b2)
{ //参考《现代颜色技术原理及应用》P88数据 double E00 = 0; //CIEDE2000色差E00 double LL1, LL2, aa1, aa2, bb1, bb2; //声明L' a' b' （1,2） double delta_LL, delta_CC, delta_hh, delta_HH; // 第二部的四个量 double kL, kC, kH; double RT = 0; //旋转函数RT double G = 0; //G表示CIELab 颜色空间a轴的调整因子,是彩度的函数. double mean_Cab = 0; //两个样品彩度的算术平均值 double SL, SC, SH, T; //------------------------------------------ //参考实验条件见P88 kL = 1; kC = 1; kH = 1; //------------------------------------------ mean_Cab = (CaiDu(a1, b1) + CaiDu(a2, b2)) / 2; double mean_Cab_pow7 = Math.Pow(mean_Cab, 7); //两彩度平均值的7次方 G = 0.5*(1-Math.Pow(mean_Cab_pow7 / (mean_Cab_pow7 + Math.Pow(25, 7)), 0.5));LL1 = L1;
aa1 = a1 * (1 + G); bb1 = b1;LL2 = L2;
aa2 = a2 * (1 + G); bb2 = b2;double CC1, CC2; //两样本的彩度值
CC1 = CaiDu(aa1, bb1); CC2 = CaiDu(aa2, bb2); double hh1, hh2; //两样本的色调角 hh1 = SeDiaoJiao(aa1, bb1); hh2 = SeDiaoJiao(aa2, bb2);delta_LL = LL1 - LL2;
delta_CC = CC1 - CC2; delta_hh = SeDiaoJiao(aa1, bb1) - SeDiaoJiao(aa2, bb2); delta_HH = 2 * Math.Sin(Math.PI*delta_hh / 360) * Math.Pow(CC1 * CC2, 0.5);//-------第三步--------------
//计算公式中的加权函数SL,SC,SH,T double mean_LL = (LL1 + LL2) / 2; double mean_CC = (CC1 + CC2) / 2; double mean_hh = (hh1 + hh2) / 2;SL = 1 + 0.015 * Math.Pow(mean_LL - 50, 2) / Math.Pow(20 + Math.Pow(mean_LL - 50, 2), 0.5);
SC = 1 + 0.045 * mean_CC; T = 1 - 0.17 * Math.Cos((mean_hh - 30) * Math.PI / 180) + 0.24 * Math.Cos((2 * mean_hh) * Math.PI / 180) + 0.32 * Math.Cos((3 * mean_hh + 6) * Math.PI / 180) - 0.2 * Math.Cos((4 * mean_hh - 63) * Math.PI / 180); SH = 1 + 0.015 * mean_CC * T;//------第四步--------
//计算公式中的RT double mean_CC_pow7 = Math.Pow(mean_CC, 7); double RC = 2 * Math.Pow(mean_CC_pow7 / (mean_CC_pow7 + Math.Pow(25, 7)), 0.5); double delta_xita = 30 * Math.Exp(-Math.Pow((mean_hh - 275) / 25, 2)); //△θ 以°为单位 RT = -Math.Sin((2 * delta_xita) * Math.PI / 180) * RC;double L_item, C_item, H_item;
L_item = delta_LL / (kL * SL); C_item = delta_CC / (kC * SC); H_item = delta_HH / (kH * SH);E00 = Math.Pow(L_item * L_item + C_item * C_item + H_item * H_item + RT * C_item * H_item, 0.5);
return E00;
} //彩度计算 private static double CaiDu(double a,double b) { double Cab = 0; Cab = Math.Pow(a * a + b * b, 0.5); return Cab; } //色调角计算 private static double SeDiaoJiao(double a, double b) { double h = 0; double hab = 0;h = (180 / Math.PI) * Math.Atan(b / a); //有正有负
if (a>0&&b>0)
{ hab = h; } else if (a<0&&b>0) { hab = 180 + h; } else if (a<0&&b<0) { hab = 180 + h; } else //a>0&&b<0 { hab = 360 + h; } return hab; } }