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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 */
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