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+
+/* Test the CIE delta E 2000 code */
+
+#include <stdio.h>
+#include <math.h>
+#include "icc.h"
+
+
+/* Reference data */
+
+#define NTESTS 34
+
+/* From the Sharma, Wu and Dalal "Implementation Notes" etc. paper: */
+struct {
+ double Lab1[3];
+ double Lab2[3];
+ double de;
+} ref[NTESTS] = {
+ { 50.0000, 2.6772, -79.7751, 50.0000, 0.0000, -82.7485, 2.0425 },
+ { 50.0000, 3.1571, -77.2803, 50.0000, 0.0000, -82.7485, 2.8615 },
+ { 50.0000, 2.8361, -74.0200, 50.0000, 0.0000, -82.7485, 3.4412 },
+ { 50.0000, -1.3802, -84.2814, 50.0000, 0.0000, -82.7485, 1.0000 },
+ { 50.0000, -1.1848, -84.8006, 50.0000, 0.0000, -82.7485, 1.0000 },
+ { 50.0000, -0.9009, -85.5211, 50.0000, 0.0000, -82.7485, 1.0000 },
+ { 50.0000, 0.0000, 0.0000, 50.0000, -1.0000, 2.0000, 2.3669 },
+ { 50.0000, -1.0000, 2.0000, 50.0000, 0.0000, 0.0000, 2.3669 },
+ { 50.0000, 2.4900, -0.0010, 50.0000, -2.4900, 0.0009, 7.1792 },
+ { 50.0000, 2.4900, -0.0010, 50.0000, -2.4900, 0.0010, 7.1792 },
+ { 50.0000, 2.4900, -0.0010, 50.0000, -2.4900, 0.0011, 7.2195 },
+ { 50.0000, 2.4900, -0.0010, 50.0000, -2.4900, 0.0012, 7.2195 },
+ { 50.0000, -0.0010, 2.4900, 50.0000, 0.0009, -2.4900, 4.8045 },
+ { 50.0000, -0.0010, 2.4900, 50.0000, 0.0010, -2.4900, 4.8045 },
+ { 50.0000, -0.0010, 2.4900, 50.0000, 0.0011, -2.4900, 4.7461 },
+ { 50.0000, 2.5000, 0.0000, 50.0000, 0.0000, -2.5000, 4.3065 },
+ { 50.0000, 2.5000, 0.0000, 73.0000, 25.0000, -18.0000, 27.1492 },
+ { 50.0000, 2.5000, 0.0000, 61.0000, -5.0000, 29.0000, 22.8977 },
+ { 50.0000, 2.5000, 0.0000, 56.0000, -27.0000, -3.0000, 31.9030 },
+ { 50.0000, 2.5000, 0.0000, 58.0000, 24.0000, 15.0000, 19.4535 },
+ { 50.0000, 2.5000, 0.0000, 50.0000, 3.1736, 0.5854, 1.0000 },
+ { 50.0000, 2.5000, 0.0000, 50.0000, 3.2972, 0.0000, 1.0000 },
+ { 50.0000, 2.5000, 0.0000, 50.0000, 1.8634, 0.5757, 1.0000 },
+ { 50.0000, 2.5000, 0.0000, 50.0000, 3.2592, 0.3350, 1.0000 },
+ { 60.2574, -34.0099, 36.2677, 60.4626, -34.1751, 39.4387, 1.2644 },
+ { 63.0109, -31.0961, -5.8663, 62.8187, -29.7946, -4.0864, 1.2630 },
+ { 61.2901, 3.7196, -5.3901, 61.4292, 2.2480, -4.9620, 1.8731 },
+ { 35.0831, -44.1164, 3.7933, 35.0232, -40.0716, 1.5901, 1.8645 },
+ { 22.7233, 20.0904, -46.6940, 23.0331, 14.9730, -42.5619, 2.0373 },
+ { 36.4612, 47.8580, 18.3852, 36.2715, 50.5065, 21.2231, 1.4146 },
+ { 90.8027, -2.0831, 1.4410, 91.1528, -1.6435, 0.0447, 1.4441 },
+ { 90.9257, -0.5406, -0.9208, 88.6381, -0.8985, -0.7239, 1.5381 },
+ { 6.7747, -0.2908, -2.4247, 5.8714, -0.0985, -2.2286, 0.6377 },
+ { 2.0776, 0.0795, -1.1350, 0.9033, -0.0636, -0.5514, 0.9082 }
+};
+
+double icmCIE2K(double *Lab1, double *Lab2);
+
+int main(void) {
+ int rv = 0;
+ int i;
+
+ printf("Starting Test:\n");
+
+#ifdef NEVER
+ for (i = 0; i < NTESTS; i++) {
+ printf("Lab1 = %f %f %f\n", ref[i].Lab1[0], ref[i].Lab1[1], ref[i].Lab1[2]);
+ printf("Lab2 = %f %f %f\n", ref[i].Lab2[0], ref[i].Lab2[1], ref[i].Lab2[2]);
+ printf("de = %f\n",ref[i].de);
+ }
+#endif
+
+ /* Test it all out */
+ for (i = 0; i < NTESTS; i++) {
+ double de;
+
+ de = icmCIE2K(ref[i].Lab1, ref[i].Lab2);
+ if (fabs(de - ref[i].de) > 0.0001) {
+ printf("Error at index %d:\n",i);
+ printf("Lab1 = %f %f %f\n", ref[i].Lab1[0], ref[i].Lab1[1], ref[i].Lab1[2]);
+ printf("Lab2 = %f %f %f\n", ref[i].Lab2[0], ref[i].Lab2[1], ref[i].Lab2[2]);
+ printf("DeltaE is %f, should be %f\n\n",de,ref[i].de);
+ rv = 1;
+ }
+ de = icmCIE2K(ref[i].Lab2, ref[i].Lab1);
+ if (fabs(de - ref[i].de) > 0.0001) {
+ printf("Error at index %d:\n",i);
+ printf("Lab1 = %f %f %f\n", ref[i].Lab2[0], ref[i].Lab2[1], ref[i].Lab2[2]);
+ printf("Lab2 = %f %f %f\n", ref[i].Lab1[0], ref[i].Lab1[1], ref[i].Lab1[2]);
+ printf("DeltaE is %f, should be %f\n\n",de,ref[i].de);
+ rv = 1;
+ }
+ }
+
+ printf("Test Finished\n");
+ return rv;
+}
+
+#ifdef NEVER /* Test implementation in icc.c */
+
+/* From the paper "The CIEDE2000 Color-Difference Formula: Implementation Notes, */
+/* Supplementary Test Data, and Mathematical Observations", by */
+/* Gaurav Sharma, Wencheng Wu and Edul N. Dalal, */
+/* Color Res. Appl., vol. 30, no. 1, pp. 21-30, Feb. 2005. */
+
+/* Return the CIEDE2000 Delta E color difference measure squared, for two Lab values */
+double icmCIE2Ksq(double *Lab0, double *Lab1) {
+ double C1, C2;
+ double h1, h2;
+ double dL, dC, dH;
+ double dsq;
+
+ /* The trucated value of PI is needed to ensure that the */
+ /* test cases pass, as one of them lies on the edge of */
+ /* a mathematical discontinuity. The precision is still */
+ /* enough for any practical use. */
+#define RAD2DEG(xx) (180.0/3.14159265358979 * (xx))
+#define DEG2RAD(xx) (3.14159265358979/180.0 * (xx))
+
+ /* Compute Cromanance and Hue angles */
+ {
+ double C1ab, C2ab;
+ double Cab, Cab7, G;
+ double a1, a2;
+
+ C1ab = sqrt(Lab0[1] * Lab0[1] + Lab0[2] * Lab0[2]);
+ C2ab = sqrt(Lab1[1] * Lab1[1] + Lab1[2] * Lab1[2]);
+ Cab = 0.5 * (C1ab + C2ab);
+ Cab7 = pow(Cab,7.0);
+ G = 0.5 * (1.0 - sqrt(Cab7/(Cab7 + 6103515625.0)));
+ a1 = (1.0 + G) * Lab0[1];
+ a2 = (1.0 + G) * Lab1[1];
+ C1 = sqrt(a1 * a1 + Lab0[2] * Lab0[2]);
+ C2 = sqrt(a2 * a2 + Lab1[2] * Lab1[2]);
+
+ if (C1 < 1e-9)
+ h1 = 0.0;
+ else {
+ h1 = RAD2DEG(atan2(Lab0[2], a1));
+ if (h1 < 0.0)
+ h1 += 360.0;
+ }
+
+ if (C2 < 1e-9)
+ h2 = 0.0;
+ else {
+ h2 = RAD2DEG(atan2(Lab1[2], a2));
+ if (h2 < 0.0)
+ h2 += 360.0;
+ }
+ }
+
+ /* Compute delta L, C and H */
+ {
+ double dh;
+
+ dL = Lab1[0] - Lab0[0];
+ dC = C2 - C1;
+ if (C1 < 1e-9 || C2 < 1e-9) {
+ dh = 0.0;
+ } else {
+ dh = h2 - h1;
+ if (dh > 180.0)
+ dh -= 360.0;
+ else if (dh < -180.0)
+ dh += 360.0;
+ }
+
+ dH = 2.0 * sqrt(C1 * C2) * sin(DEG2RAD(0.5 * dh));
+ }
+
+ {
+ double L, C, h, T;
+ double hh, ddeg;
+ double C7, RC, L50sq, SL, SC, SH, RT;
+ double dLsq, dCsq, dHsq, RCH;
+
+ L = 0.5 * (Lab0[0] + Lab1[0]);
+ C = 0.5 * (C1 + C2);
+ if (C1 < 1e-9 || C2 < 1e-9) {
+ h = h1 + h2;
+ } else {
+ h = h1 + h2;
+ if (fabs(h1 - h2) > 180.0) {
+ if (h < 360.0)
+ h += 360.0;
+ else if (h >= 360.0)
+ h -= 360.0;
+ }
+ h *= 0.5;
+ }
+ T = 1.0 - 0.17 * cos(DEG2RAD(h-30.0)) + 0.24 * cos(DEG2RAD(2.0 * h))
+ + 0.32 * cos(DEG2RAD(3.0 * h + 6.0)) - 0.2 * cos(DEG2RAD(4.0 * h - 63.0));
+ hh = (h - 275.0)/25.0;
+ ddeg = 30.0 * exp(-hh * hh);
+ C7 = pow(C,7.0);
+ RC = 2.0 * sqrt(C7/(C7 + 6103515625.0));
+ L50sq = (L - 50.0) * (L - 50.0);
+ SL = 1.0 + (0.015 * L50sq)/sqrt(20.0 + L50sq);
+ SC = 1.0 + 0.045 * C;
+ SH = 1.0 + 0.015 * C * T;
+ RT = -sin(DEG2RAD(2 * ddeg)) * RC;
+
+ dLsq = dL/SL;
+ dCsq = dC/SC;
+ dHsq = dH/SH;
+
+ RCH = RT * dCsq * dHsq;
+
+ dLsq *= dLsq;
+ dCsq *= dCsq;
+ dHsq *= dHsq;
+
+ dsq = dLsq + dCsq + dHsq + RCH;
+ }
+
+ return dsq;
+
+#undef RAD2DEG
+#undef DEG2RAD
+}
+
+/* Return the CIE2DE000 Delta E color difference measure for two Lab values */
+double icmCIE2K(double *Lab0, double *Lab1) {
+ return sqrt(icmCIE2Ksq(Lab0, Lab1));
+}
+
+#endif /* NEVER */