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argyllcms/xicc/cam97s3.c
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2026-08-20 20:28:40 +01:00

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19 KiB
C

/*
* cam97s3hk
*
* Color Appearance Model, based on
* CIECAM97, "Revision for Practical Applications"
* by Mark D. Fairchild, with the addition of the Viewing Flare
* model described on page 487 of "Digital Color Management",
* by Edward Giorgianni and Thomas Madden, and the
* Helmholtz-Kohlraush effect, using the equation
* the Bradford-Hunt 96C model as detailed in Mark Fairchilds
* book "Color Appearance Models".
*
* Author: Graeme W. Gill
* Date: 5/10/00
* Version: 1.20
*
* Copyright 2000, 2002 Graeme W. Gill
* Please refer to COPYRIGHT file for details.
* This material is licenced under the GNU AFFERO GENERAL PUBLIC LICENSE Version 3 :-
* see the License.txt file for licencing details.
*/
/* Note that XYZ values are normalised to 1.0 consistent */
/* with the ICC convention (not 100.0 as assumed by the CIECAM spec.) */
/* Note that all whites are assumed to be normalised (ie. Y = 1.0) */
/* Various changes have been made to allow the CAM conversions to */
/* function over a much greater range of XYZ and Jab values that */
/* the functions are described in the above references. This is */
/* because such values arise in the process of gamut mapping, and */
/* in scanning through the grid of PCS values needed to fill in */
/* the A2B table of an ICC profile. Such values have no correlation */
/* to a real color value, but none the less need to be handled without */
/* causing an exception, in a geometrically consistent and reversible */
/* fashion. */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "xcam.h"
#include "cam97s3.h"
#undef DIAG /* Print internal value diagnostics for each conversion */
#define CAM_PI 3.14159265359
/* Utility function */
/* Return a viewing condition enumeration from the given Ambient and */
/* Adapting/Surround Luminance. */
static ViewingCondition cam97_Ambient2VC(
double La, /* Ambient Luminance (cd/m^2) */
double Lv /* Luminance of white in the Viewing/Scene/Image field (cd/m^2) */
) {
double r;
if (fabs(La) < 1e-10) /* Hmm. */
r = 1.0;
else
r = La/Lv;
if (r < 0.01)
return vc_dark;
if (r < 0.2)
return vc_dim;
return vc_average;
}
static void cam_free(cam97s3 *s);
static int set_view(struct _cam97s3 *s, ViewingCondition Ev, double Wxyz[3],
double La, double Yb, double Lv, double Yf, double Fxyz[3],
int hk);
static int XYZ_to_cam(struct _cam97s3 *s, double *Jab, double *xyz);
static int cam_to_XYZ(struct _cam97s3 *s, double *xyz, double *Jab);
/* Create a cam97s3 conversion object, with default viewing conditions */
cam97s3 *new_cam97s3(void) {
cam97s3 *s;
// double D50[3] = { 0.9642, 1.0000, 0.8249 };
if ((s = (cam97s3 *)calloc(1, sizeof(cam97s3))) == NULL) {
fprintf(stderr,"cam97s3: malloc failed allocating object\n");
exit(-1);
}
/* Initialise methods */
s->del = cam_free;
s->set_view = set_view;
s->XYZ_to_cam = XYZ_to_cam;
s->cam_to_XYZ = cam_to_XYZ;
/* Set a default viewing condition ?? */
/* set_view(s, vc_average, D50, 33.0, 0.2, 0.0, 0.0, D50, 0); */
return s;
}
static void cam_free(cam97s3 *s) {
if (s != NULL)
free(s);
}
/* A version of the pow() function that preserves the */
/* sign of its first argument. */
static double spow(double x, double y) {
return x < 0.0 ? -pow(-x,y) : pow(x,y);
}
static int set_view(
cam97s3 *s,
ViewingCondition Ev, /* Enumerated Viewing Condition */
double Wxyz[3], /* Reference/Adapted White XYZ (Y range 0.0 .. 1.0) */
double La, /* Adapting/Surround Luminance cd/m^2 */
double Yb, /* Relative Luminance of Background to reference white */
double Lv, /* Luminance of white in the Viewing/Scene/Image field (cd/m^2) */
/* Ignored if Ev is set to other than vc_none */
double Yf, /* Flare as a fraction of the reference white (Y range 0.0 .. 1.0) */
double Fxyz[3], /* The Flare white coordinates (typically the Ambient color) */
int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
) {
double tt;
if (Ev == vc_none) /* Compute enumerated viewing condition */
Ev = cam97_Ambient2VC(La, Lv);
/* Transfer parameters to the object */
s->Ev = Ev;
s->Wxyz[0] = Wxyz[0];
s->Wxyz[1] = Wxyz[1];
s->Wxyz[2] = Wxyz[2];
s->Yb = Yb > 0.005 ? Yb : 0.005; /* Set minimum to avoid divide by 0.0 */
s->La = La;
s->Yf = Yf;
s->Fxyz[0] = Fxyz[0];
s->Fxyz[1] = Fxyz[1];
s->Fxyz[2] = Fxyz[2];
s->hk = hk;
/* Compute the internal parameters by category */
switch(s->Ev) {
case vc_dark:
s->C = 0.525;
s->Nc = 0.8;
s->F = 0.9;
break;
case vc_dim:
s->C = 0.59;
s->Nc = 0.95;
s->F = 0.9;
break;
case vc_cut_sheet:
s->C = 0.41;
s->Nc = 0.8;
s->F = 0.9;
break;
default: /* average */
s->C = 0.69;
s->Nc = 1.0;
s->F = 1.0;
break;
}
/* Compute values that only change with viewing parameters */
/* Figure out the Flare contribution to the flareless XYZ input */
tt = s->Yf * s->Wxyz[1]/s->Fxyz[1];
s->Fsxyz[0] = tt * s->Fxyz[0];
s->Fsxyz[1] = tt * s->Fxyz[1];
s->Fsxyz[2] = tt * s->Fxyz[2];
/* Rescale so that the sum of the flare and the input doesn't exceed white */
s->Fsc = s->Wxyz[1]/(s->Fsxyz[1] + s->Wxyz[1]);
s->Fsxyz[0] *= s->Fsc;
s->Fsxyz[1] *= s->Fsc;
s->Fsxyz[2] *= s->Fsc;
s->Fisc = 1.0/s->Fsc;
/* Sharpened cone response white values */
s->rgbW[0] = 0.8562 * s->Wxyz[0] + 0.3372 * s->Wxyz[1] - 0.1934 * s->Wxyz[2];
s->rgbW[1] = -0.8360 * s->Wxyz[0] + 1.8327 * s->Wxyz[1] + 0.0033 * s->Wxyz[2];
s->rgbW[2] = 0.0357 * s->Wxyz[0] - 0.0469 * s->Wxyz[1] + 1.0112 * s->Wxyz[2];
/* Degree of chromatic adaptation */
s->D = s->F - (s->F / (1.0 + 2.0 * pow(s->La, 0.25) + s->La * s->La / 300.0) );
/* Chromaticaly transformed white value */
s->rgbcW[0] = (s->D * (1.0/s->rgbW[0]) + 1.0 - s->D ) * s->rgbW[0];
s->rgbcW[1] = (s->D * (1.0/s->rgbW[1]) + 1.0 - s->D ) * s->rgbW[1];
s->rgbcW[2] = (s->D * (1.0/s->rgbW[2]) + 1.0 - s->D ) * s->rgbW[2];
/* Transform from spectrally sharpened, to Hunt-Pointer_Estevez cone space */
s->rgbpW[0] = 0.6962394300923847 * s->rgbcW[0]
+ 0.2492311682812913 * s->rgbcW[1]
+ 0.0545394016263241 * s->rgbcW[2];
s->rgbpW[1] = 0.3054822636273227 * s->rgbcW[0]
+ 0.5921282520433844 * s->rgbcW[1]
+ 0.1023894843292929 * s->rgbcW[2];
s->rgbpW[2] = -0.0139683251072516 * s->rgbcW[0]
+ 0.0278065725014340 * s->rgbcW[1]
+ 0.9861617526058175 * s->rgbcW[2];
/* Background induction factor */
s->n = s->Yb/ s->Wxyz[1];
s->nn = pow((1.64 - pow(0.29, s->n)), 1.41); /* Pre computed value */
/* Lightness contrast factor ?? */
{
double k;
k = 1.0 / (5.0 * s->La + 1.0);
s->Fl = 0.2 * pow(k , 4.0) * 5.0 * s->La
+ 0.1 * pow(1.0 - pow(k , 4.0) , 2.0) * pow(5.0 * s->La , 1.0/3.0);
}
/* Background and Chromatic brightness induction factors */
s->Nbb = 0.725 * pow(1.0/s->n, 0.2);
s->Ncb = s->Nbb;
/* Base exponential nonlinearity */
s->z = 1.0 + pow(s->n , 0.5);
/* Post-adapted cone response of white */
tt = pow(s->Fl * s->rgbpW[0], 0.73);
s->rgbaW[0] = (40.0 * tt / (tt + 2.0)) + 1.0;
tt = pow(s->Fl * s->rgbpW[1], 0.73);
s->rgbaW[1] = (40.0 * tt / (tt + 2.0)) + 1.0;
tt = pow(s->Fl * s->rgbpW[2], 0.73);
s->rgbaW[2] = (40.0 * tt / (tt + 2.0)) + 1.0;
/* Achromatic response of white */
s->Aw = (2.0 * s->rgbaW[0] + s->rgbaW[1] + (1.0/20.0) * s->rgbaW[2] - 3.05) * s->Nbb;
#ifdef DIAG
printf("Scene parameters:\n");
printf("Viewing condition Ev = %d\n",s->Ev);
printf("Ref white Wxyz = %f %f %f\n", s->Wxyz[0], s->Wxyz[1], s->Wxyz[2]);
printf("Relative liminance of background Yb = %f\n", s->Yb);
printf("Adapting liminance La = %f\n", s->La);
printf("Flare Yf = %f\n", s->Yf);
printf("Flare color Fxyz = %f %f %f\n", s->Fxyz[0], s->Fxyz[1], s->Fxyz[2]);
printf("Internal parameters:\n");
printf("Surround Impact C = %f\n", s->C);
printf("Chromatic Induction Nc = %f\n", s->Nc);
printf("Adaptation Degree F = %f\n", s->F);
printf("Pre-computed values\n");
printf("Sharpened cone white rgbW = %f %f %f\n", s->rgbW[0], s->rgbW[1], s->rgbW[2]);
printf("Degree of chromatic adaptation D = %f\n", s->D);
printf("Chromatically transformed white rgbcW = %f %f %f\n", s->rgbcW[0], s->rgbcW[1], s->rgbcW[2]);
printf("Hunter-P-E cone response white rgbpW = %f %f %f\n", s->rgbpW[0], s->rgbpW[1], s->rgbpW[2]);
printf("Background induction factor n = %f\n", s->n);
printf("Lightness contrast factor Fl = %f\n", s->Fl);
printf("Background brightness induction factor Nbb = %f\n", s->Nbb);
printf("Chromatic brightness induction factor Ncb = %f\n", s->Ncb);
printf("Base exponential nonlinearity z = %f\n", s->z);
printf("Post adapted cone response white rgbaW = %f %f %f\n", s->rgbaW[0], s->rgbaW[1], s->rgbaW[2]);
printf("Achromatic response of white Aw = %f\n", s->Aw);
#endif
return 0;
}
/* Conversions */
static int XYZ_to_cam(
struct _cam97s3 *s,
double Jab[3],
double XYZ[3]
) {
int i;
double xyz[3], rgb[3], rgbp[3], rgba[3], rgbc[3];
double a, b, nab, J, C, h, e, A, ss;
double ttd, tt;
/* Add in flare */
xyz[0] = s->Fsc * XYZ[0] + s->Fsxyz[0];
xyz[1] = s->Fsc * XYZ[1] + s->Fsxyz[1];
xyz[2] = s->Fsc * XYZ[2] + s->Fsxyz[2];
/* Spectrally sharpened cone responses */
rgb[0] = 0.8562 * xyz[0] + 0.3372 * xyz[1] - 0.1934 * xyz[2];
rgb[1] = -0.8360 * xyz[0] + 1.8327 * xyz[1] + 0.0033 * xyz[2];
rgb[2] = 0.0357 * xyz[0] - 0.0469 * xyz[1] + 1.0112 * xyz[2];
/* Chromaticaly transformed sample value */
rgbc[0] = (s->D * (1.0/s->rgbW[0]) + 1.0 - s->D ) * rgb[0];
rgbc[1] = (s->D * (1.0/s->rgbW[1]) + 1.0 - s->D ) * rgb[1];
rgbc[2] = (s->D * (1.0/s->rgbW[2]) + 1.0 - s->D ) * rgb[2];
/* Transform from spectrally sharpened, to Hunt-Pointer_Estevez cone space */
rgbp[0] = 0.6962394300923847 * rgbc[0]
+ 0.2492311682812913 * rgbc[1]
+ 0.0545394016263241 * rgbc[2];
rgbp[1] = 0.3054822636273227 * rgbc[0]
+ 0.5921282520433844 * rgbc[1]
+ 0.1023894843292929 * rgbc[2];
rgbp[2] = -0.0139683251072516 * rgbc[0]
+ 0.0278065725014340 * rgbc[1]
+ 0.9861617526058175 * rgbc[2];
/* Post-adapted cone response of sample. */
/* rgba[] has a minimum value of 1.0 for XYZ[] = 0 and no flare. */
/* We add linear segments at the ends of this conversion to */
/* allow numerical handling of a wider range of values */
for (i = 0; i < 3; i++) {
if (rgbp[i] < 0.0) {
tt = pow(s->Fl * -rgbp[i], 0.73);
if (tt < 78.0)
rgba[i] = (2.0 - 39.0 * tt) / (tt + 2.0);
else
rgba[i] = (2.0 - tt) / 2.0;
} else {
tt = pow(s->Fl * rgbp[i], 0.73);
if (tt < 78.0)
rgba[i] = (41.0 * tt + 2.0) / (tt + 2.0);
else
rgba[i] = (tt + 2.0) / 2.0;
}
}
/* Preliminary red-green & yellow-blue opponent dimensions */
a = rgba[0] - 12.0 * rgba[1]/11.0 + rgba[2]/11.0;
b = (1.0/9.0) * (rgba[0] + rgba[1] - 2.0 * rgba[2]);
nab = sqrt(a * a + b * b); /* Normalised a, b */
/* Hue angle */
h = (180.0/CAM_PI) * atan2(b,a);
h = (h < 0.0) ? h + 360.0 : h;
/* Eccentricity factor */
{
double r, e1, e2, h1, h2;
if (h <= 20.14)
e1 = 0.8565, e2 = 0.8, h1 = 0.0, h2 = 20.14;
else if (h <= 90.0)
e1 = 0.8, e2 = 0.7, h1 = 20.14, h2 = 90.0;
else if (h <= 164.25)
e1 = 0.7, e2 = 1.0, h1 = 90.0, h2 = 164.25;
else if (h <= 237.53)
e1 = 1.0, e2 = 1.2, h1 = 164.25, h2 = 237.53;
else
e1 = 1.2, e2 = 0.8565, h1 = 237.53, h2 = 360.0;
r = (h-h1)/(h2-h1);
#ifdef CIECAM97S3_SPLINE_E
r = r * r * (3.0 - 2.0 * r);
#endif
e = e1 + r * (e2-e1);
}
/* Achromatic response */
/* Note that the minimum values of rgba[] for XYZ = 0 is 1.0, */
/* hence magic 3.05 below comes from the following weighting of rgba[], */
/* to base A at 0.0 */
A = (2.0 * rgba[0] + rgba[1] + (1.0/20.0) * rgba[2] - 3.05) * s->Nbb;
/* Lightness */
J = spow(A/s->Aw, s->C * s->z); /* J/100 - keep Sign */
/* Saturation */
/* Note that the minimum values for rgba[] for XYZ = 0 is 1.0 */
/* Hence magic 3.05 below comes from the following weighting of rgba[] */
ttd = rgba[0] + rgba[1] + (21.0/20.0) * rgba[2];
ttd = fabs(ttd);
if (ttd < 3.05) { /* If not physically realisable, limit denominator */
ttd = 3.05; /* hence limit max ss value */
}
ss = (50000.0/13.0 * s->Nc * s->Ncb * nab * e) / ttd;
/* Chroma - Keep C +ve and make sure J doesn't force it to 0 */
tt = fabs(J);
if (tt < 0.01)
tt = 0.01;
C = 0.7487 * pow(ss, 0.973) * pow(tt, 0.945 * s->n) * s->nn;
/* Helmholtz-Kohlraush effect */
if (s->hk) {
double kk = C/300.0 * sin(CAM_PI * fabs(0.5 * (h - 90.0))/180.0);
if (kk > 0.9) /* Limit kk to a reasonable range */
kk = 0.9;
J = J + (1.0 - J) * kk;
}
J *= 100.0; /* Scale J */
/* Compute Jab value */
Jab[0] = J;
if (nab > 1e-10) {
Jab[1] = C * a/nab;
Jab[2] = C * b/nab;
} else {
Jab[1] = 0.0;
Jab[2] = 0.0;
}
#ifdef DIAG
printf("Processing:\n");
printf("XYZ = %f %f %f\n", XYZ[0], XYZ[1], XYZ[2]);
printf("Including flare XYZ = %f %f %f\n", xyz[0], xyz[1], xyz[2]);
printf("Sharpened cone sample rgb = %f %f %f\n", rgb[0], rgb[1], rgb[2]);
printf("Chromatically transformed sample value rgbc = %f %f %f\n", rgbc[0], rgbc[1], rgbc[2]);
printf("Hunt-P-E cone space rgbp = %f %f %f\n", rgbp[0], rgbp[1], rgbp[2]);
printf("Post adapted cone response rgba = %f %f %f\n", rgba[0], rgba[1], rgba[2]);
printf("Prelim red green a = %f, b = %f\n", a, b);
printf("Hue angle h = %f\n", h);
printf("Eccentricity factor e = %f\n", e);
printf("Achromatic response A = %f\n", A);
printf("Lightness J = %f\n", J);
printf("Saturation ss = %f\n", ss);
printf("Chroma C = %f\n", C);
printf("Jab = %f %f %f\n", Jab[0], Jab[1], Jab[2]);
#endif
return 0;
}
static int cam_to_XYZ(
struct _cam97s3 *s,
double XYZ[3],
double Jab[3]
) {
int i;
double xyz[3], rgb[3], rgbp[3], rgba[3], rgbc[3];
double ja, jb, aa, ab, a, b, J, C, h, e, A, ss;
double tt, ttA, tte;
J = Jab[0] * 0.01; /* J/100 */
ja = Jab[1];
jb = Jab[2];
/* Compute hue angle */
h = (180.0/CAM_PI) * atan2(jb, ja);
h = (h < 0.0) ? h + 360.0 : h;
/* Compute chroma value */
C = sqrt(ja * ja + jb * jb); /* Must be Always +ve */
/* Helmholtz-Kohlraush effect */
if (s->hk) {
double kk = C/300.0 * sin(CAM_PI * fabs(0.5 * (h - 90.0))/180.0);
if (kk > 0.9) /* Limit kk to a reasonable range */
kk = 0.9;
J = (J - kk)/(1.0 - kk);
}
/* Eccentricity factor */
{
double r, e1, e2, h1, h2;
if (h <= 20.14)
e1 = 0.8565, e2 = 0.8, h1 = 0.0, h2 = 20.14;
else if (h <= 90.0)
e1 = 0.8, e2 = 0.7, h1 = 20.14, h2 = 90.0;
else if (h <= 164.25)
e1 = 0.7, e2 = 1.0, h1 = 90.0, h2 = 164.25;
else if (h <= 237.53)
e1 = 1.0, e2 = 1.2, h1 = 164.25, h2 = 237.53;
else
e1 = 1.2, e2 = 0.8565, h1 = 237.53, h2 = 360.0;
r = (h-h1)/(h2-h1);
#ifdef CIECAM97S3_SPLINE_E
r = r * r * (3.0 - 2.0 * r);
#endif
e = e1 + r * (e2-e1);
}
/* Achromatic response */
A = spow(J, 1.0/(s->C * s->z)) * s->Aw; /* Keep sign of J */
/* Saturation - keep +ve and make sure J = 0 doesn't blow it up. */
tt = fabs(J);
if (tt < 0.01)
tt = 0.01;
ss = pow(C/(0.7487 * pow(tt, 0.945 * s->n) * s->nn), 1.0/0.973); /* keep +ve */
/* Compute a & b, taking care of numerical problems */
aa = fabs(ja);
ab = fabs(jb);
ttA = (A/s->Nbb)+3.05; /* Common factor */
tte = 50000.0/13.0 * e * s->Nc * s->Ncb; /* Common factor */
if (aa < 1e-10 && ab < 1e-10) {
a = ja;
b = jb;
} else if (aa > ab) {
double tanh = jb/ja;
double sign = (h > 90.0 && h <= 270.0) ? -1.0 : 1.0;
if (ttA < 0.0)
sign = -sign;
a = (ss * ttA)
/ (sign * sqrt(1.0 + tanh * tanh) * tte + (ss * (11.0/23.0 + (108.0/23.0) * tanh)));
b = a * tanh;
} else { /* ab > aa */
double itanh = ja/jb;
double sign = (h > 180.0 && h <= 360.0) ? -1.0 : 1.0;
if (ttA < 0.0)
sign = -sign;
b = (ss * ttA)
/ (sign * sqrt(1.0 + itanh * itanh) * tte + (ss * (108.0/23.0 + (11.0/23.0) * itanh)));
a = b * itanh;
}
{ /* Check if we have a limited saturation because it is non-realisable */
double tts;
double nab = sqrt(a * a + b * b); /* Normalised a, b */
tts = (nab * tte) / 3.05; /* Limited saturation number */
if (tts < ss) { /* Saturation exceeds it anyway so must have limited denom. */
a *= ss/tts; /* Rescale a & b to account for extra ss */
b *= ss/tts; /* even though denom was limited (since nab was in numerator). */
}
}
/* Post-adapted cone response of sample */
rgba[0] = (20.0/61.0) * ttA
+ ((41.0 * 11.0)/(61.0 * 23.0)) * a
+ ((288.0 * 1.0)/(61.0 * 23.0)) * b;
rgba[1] = (20.0/61.0) * ttA
- ((81.0 * 11.0)/(61.0 * 23.0)) * a
- ((261.0 * 1.0)/(61.0 * 23.0)) * b;
rgba[2] = (20.0/61.0) * ttA
- ((20.0 * 11.0)/(61.0 * 23.0)) * a
- ((20.0 * 315.0)/(61.0 * 23.0)) * b;
/* Hunt-Pointer_Estevez cone space */
/* (with linear segments at the ends0 */
tt = 1.0/s->Fl;
for (i = 0; i < 3; i++) {
if (rgba[i] < 1.0) {
double ta = rgba[i] > -38.0 ? rgba[i] : -38.0;
rgbp[i] = -tt * pow((2.0 - 2.0 * rgba[i] )/(39.0+ ta), 1.0/0.73);
} else {
double ta = rgba[i] < 40.0 ? rgba[i] : 40.0;
rgbp[i] = tt * pow((2.0 * rgba[i] -2.0)/(41.0 - ta), 1.0/0.73);
}
}
/* Chromaticaly transformed sample value */
rgbc[0] = 1.7605948990728097 * rgbp[0]
- 0.7400833814121892 * rgbp[1]
- 0.0205291236096116 * rgbp[2];
rgbc[1] = -0.9170843265341294 * rgbp[0]
+ 2.0826033118941054 * rgbp[1]
- 0.1655098145167107 * rgbp[2];
rgbc[2] = 0.0507964678367941 * rgbp[0]
- 0.0692054676442407 * rgbp[1]
+ 1.0184084918427683 * rgbp[2];
/* Spectrally sharpened cone responses */
rgb[0] = rgbc[0]/(s->D * (1.0/s->rgbW[0]) + 1.0 - s->D);
rgb[1] = rgbc[1]/(s->D * (1.0/s->rgbW[1]) + 1.0 - s->D);
rgb[2] = rgbc[2]/(s->D * (1.0/s->rgbW[2]) + 1.0 - s->D);
/* XYZ values */
xyz[0] = 0.9873999149199270 * rgb[0]
- 0.1768250198556842 * rgb[1]
+ 0.1894251049357572 * rgb[2];
xyz[1] = 0.4504351090445316 * rgb[0]
+ 0.4649328977527109 * rgb[1]
+ 0.0846319932027575 * rgb[2];
xyz[2] = -0.0139683251072516 * rgb[0]
+ 0.0278065725014340 * rgb[1]
+ 0.9861617526058175 * rgb[2];
/* Subtract flare */
XYZ[0] = s->Fisc * (xyz[0] - s->Fsxyz[0]);
XYZ[1] = s->Fisc * (xyz[1] - s->Fsxyz[1]);
XYZ[2] = s->Fisc * (xyz[2] - s->Fsxyz[2]);
#ifdef DIAG
printf("Processing:\n");
printf("Jab = %f %f %f\n", Jab[0], Jab[1], Jab[2]);
printf("Chroma C = %f\n", C);
printf("Saturation ss = %f\n", ss);
printf("Lightness J = %f\n", J * 100.0);
printf("Achromatic response A = %f\n", A);
printf("Eccentricity factor e = %f\n", e);
printf("Hue angle h = %f\n", h);
printf("Prelim red green a = %f, b = %f\n", a, b);
printf("Post adapted cone response rgba = %f %f %f\n", rgba[0], rgba[1], rgba[2]);
printf("Hunt-P-E cone space rgbp = %f %f %f\n", rgbp[0], rgbp[1], rgbp[2]);
printf("Chromatically transformed sample value rgbc = %f %f %f\n", rgbc[0], rgbc[1], rgbc[2]);
printf("Sharpened cone sample rgb = %f %f %f\n", rgb[0], rgb[1], rgb[2]);
printf("Including flare XYZ = %f %f %f\n", xyz[0], xyz[1], xyz[2]);
printf("XYZ = %f %f %f\n", XYZ[0], XYZ[1], XYZ[2]);
#endif
return 0;
}