public static double Difference(RGB rgb1, RGB rgb2, ColorDifference type) { switch (type) { case ColorDifference.RGB_std_deviation: return(RGB_std_deviation(rgb1, rgb2)); case ColorDifference.CIE76: return(CIE76(rgb1, rgb2)); case ColorDifference.CIE94: return(CIE94(rgb1, rgb2)); case ColorDifference.CIE2000: return(CIE2000(rgb1, rgb2)); case ColorDifference.dRed: return(Math.Abs(rgb1.Red - rgb2.Red)); case ColorDifference.dGreen: return(Math.Abs(rgb1.Green - rgb2.Green)); case ColorDifference.dBlue: return(Math.Abs(rgb1.Blue - rgb2.Blue)); case ColorDifference.Grey: return(Math.Abs(ColorModelConverter.RGBtoGray(rgb1) - ColorModelConverter.RGBtoGray(rgb2))); default: return(0); } }
private static double CIE76(RGB rgb1, RGB rgb2) { CIELab Lab1 = ColorModelConverter.RGBtoLab(rgb1.Red, rgb1.Green, rgb1.Blue); CIELab Lab2 = ColorModelConverter.RGBtoLab(rgb2.Red, rgb2.Green, rgb2.Blue); return(Math.Sqrt(( Math.Pow(Lab1.L - Lab2.L, 2) + Math.Pow(Lab1.A - Lab2.A, 2) + Math.Pow(Lab1.B - Lab2.B, 2)) )); }
private static double CIE94(RGB rgb1, RGB rgb2) { CIELab Lab1 = ColorModelConverter.RGBtoLab(rgb1.Red, rgb1.Green, rgb1.Blue); CIELab Lab2 = ColorModelConverter.RGBtoLab(rgb2.Red, rgb2.Green, rgb2.Blue); double Da = Lab1.A - Lab2.A; double Db = Lab1.B - Lab2.B; double C1 = Math.Sqrt(Math.Pow(Lab1.A, 2) + Math.Pow(Lab1.B, 2)); double C2 = Math.Sqrt(Math.Pow(Lab2.A, 2) + Math.Pow(Lab2.B, 2)); double Sc = 1 + K1 * C1; double Sh = 1 + K2 * C1; double Dl = Lab1.L - Lab2.L; double Dc = C1 - C2; double Dh2 = Math.Pow(Da, 2) + Math.Pow(Db, 2) - Math.Pow(Dc, 2); return(Math.Sqrt(Math.Pow(Dl, 2) + Math.Pow(Dc / Sc, 2) + Dh2 / Math.Pow(Sh, 2))); }
private static double CIE2000(RGB rgb1, RGB rgb2) { CIELab Lab1 = ColorModelConverter.RGBtoLab(rgb1.Red, rgb1.Green, rgb1.Blue); CIELab Lab2 = ColorModelConverter.RGBtoLab(rgb2.Red, rgb2.Green, rgb2.Blue); double L1 = Lab1.L; double L2 = Lab2.L; double a1 = Lab1.A; double a2 = Lab2.A; double b1 = Lab1.B; double b2 = Lab2.B; double Ltd = (L1 + L2) / 2; double C1 = Math.Sqrt(Math.Pow(a1, 2) + Math.Pow(b1, 2)); double C2 = Math.Sqrt(Math.Pow(a2, 2) + Math.Pow(b2, 2)); double Ct = (C1 + C2) / 2; double Ct7 = Math.Pow(Ct, 7); double G = (1 - Math.Sqrt(Ct7 / (Ct7 + pow25_7))) / 2; double ad1 = a1 * (1 + G); double ad2 = a2 * (1 + G); double Cd1 = Math.Sqrt(Math.Pow(ad1, 2) + Math.Pow(b1, 2)); double Cd2 = Math.Sqrt(Math.Pow(ad2, 2) + Math.Pow(b2, 2)); double Ctd = (Cd1 + Cd2) / 2; double atanhd1 = Math.Atan2(b1, ad1); double hd1 = atanhd1 + (atanhd1 >= 0 ? 0 : deg360); double atanhd2 = Math.Atan2(b2, ad2); double hd2 = atanhd2 + (atanhd2 >= 0 ? 0 : deg360); double sdh = hd1 + hd2; double dh1 = hd1 - hd2; double adh1 = Math.Abs(dh1); double Htd = (sdh + (adh1 > deg180 ? deg360 : 0)) / 2; double T = 1 - 0.17 * Math.Cos(Htd - deg30) + 0.24 * Math.Cos(2 * Htd) + 0.32 * Math.Cos(2 * Htd + deg6) - 0.20 * Math.Cos(4 * Htd - deg63); double dh2 = hd2 - hd1; double adh2 = Math.Abs(dh2); double dhd = adh2 <= deg180 ? dh2 : (hd2 <= hd1 ? (dh2 + deg360) : (dh2 - deg360)); double dLd = L2 - L1; double dCd = Cd2 - Cd1; double dHd = 2 * Math.Sqrt(Cd1 * Cd2) * Math.Sin(dhd / 2); double Ltd2 = Math.Pow(Ltd - 50, 2); double Sl = 1 + (K2 * Ltd2) / Math.Sqrt(20 + Ltd2); double Sc = 1 + K1 * Ctd; double Sh = 1 + K2 * Ctd * T; double ctd7 = Math.Pow(Ctd, 7); double dO = 30 * Math.Exp(-Math.Pow((Htd - deg275) / 25, 2)); double Rc = 2 * Math.Sqrt(ctd7 / (ctd7 + pow25_7)); double Rt = -Rc *Math.Sin(2 *dO); double SDE = Math.Pow(dLd / Sl, 2) + Math.Pow(dCd / Sc, 2) + Math.Pow(dHd / Sh, 2) + Rt * (dCd / Sc) * (dHd / Sh); return(Math.Sqrt(SDE)); }