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-rw-r--r--xicc/cam02.c94
1 files changed, 67 insertions, 27 deletions
diff --git a/xicc/cam02.c b/xicc/cam02.c
index 1ab6abc..3684a78 100644
--- a/xicc/cam02.c
+++ b/xicc/cam02.c
@@ -39,6 +39,21 @@
/* Note that all whites are assumed to be normalised (ie. Y = 1.0) */
/*
+ TTBD: Should convert to using Timo Kunkel and Erik Reinhard's simplified
+ and improved version of CIECAM02 (ie. "CIECAM02-KR").
+
+ The rgbp compression has it's problems in terms of perceptual
+ uniformity. A color with one component near zero might shift
+ all the components to -ve values on inverse conversion - ie.
+ a 1 DE shift in Jab becomes a masive DE in XYZ/Lab/perceptual,
+ with (say) a darl red becomong black because the blue
+ value is small. One way around this is to re-introduce
+ a flag to turn off perfect symetry by disabling
+ expansion on the reverse conversion.
+
+ */
+
+/*
Various additions and changes have been made to allow the CAM
conversions to and from an unbounded range of XYZ and Jab values,
in a (somewhat) geometrically consistent maner. This is because
@@ -106,6 +121,7 @@
#include "numlib.h"
#define ENABLE_COMPR /* [Def] Enable XYZ compression */
+#undef ENABLE_DECOMPR /* [Undef] Enable XYZ de-compression */
#define ENABLE_BLUE_ANGLE_FIX /* [Def] Limit maximum blue angle */
#define ENABLE_DDL /* [Def] Enable k1,k2,k3 overall ss limit values (seems to be the best scheme) */
#undef ENABLE_SS /* [Undef] Disable overall ss limit values (not the scheme used) */
@@ -123,10 +139,10 @@
#undef DISABLE_HHKR /* Debug - disable Helmholtz-Kohlraush */
#ifdef ENABLE_COMPR
-# define BC_WHMINY 0.3 /* [0.3] Compression direction minimum Y value */
-# define BC_RANGE_R 0.01 /* [0.01] Set compression range as prop. of distance to neutral - red */
-# define BC_RANGE_G 0.05 /* [0.05] Set compression range as prop. of distance to neutral - green*/
-# define BC_RANGE_B 0.10 /* [0.10] Set compression range as prop. of distance to neutral - blue */
+# define BC_WHMINY 0.2 /* [0.2] Compression direction minimum Y value */
+# define BC_RANGE_R 0.01 /* [0.02] Set comp. range as prop. of distance to neutral - red */
+# define BC_RANGE_G 0.01 /* [0.02] Set comp. range as prop. of distance to neutral - green*/
+# define BC_RANGE_B 0.01 /* [0.02] Set comp. range as prop. of distance to neutral - blue */
# define BC_MAXRANGE 0.13 /* [0.13] Maximum compression range */
# define BC_LIMIT 0.7 /* [0.7] Correction limit (abs. rgbp distance shift) */
#endif /* ENABLE_COMPR */
@@ -174,7 +190,7 @@ double minj = 1e38, maxj = -1e38;
static void cam_free(cam02 *s);
static int set_view(struct _cam02 *s, ViewingCondition Ev, double Wxyz[3],
- double La, double Yb, double Lv, double Yf, double Fxyz[3],
+ double La, double Yb, double Lv, double Yf, double Yg, double Gxyz[3],
int hk);
static int XYZ_to_cam(struct _cam02 *s, double *Jab, double *xyz);
static int cam_to_XYZ(struct _cam02 *s, double *xyz, double *Jab);
@@ -263,7 +279,9 @@ double Yb, /* Relative Luminance of Background to reference white (range 0.0 ..
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) */
+double Yg, /* Flare as a fraction of the ambient (Y range 0.0 .. 1.0) */
+double Gxyz[3], /* The Glare white coordinates (typically the Ambient color) */
+ /* If <= 0 will Wxyz will be used. */
int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
) {
double tt, t1, t2;
@@ -271,7 +289,8 @@ int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
int i;
if (Ev == vc_none) {
- /* Compute the internal parameters by interpolation */
+ /* Compute the internal parameters from the */
+ /* ratio of La to Lv by interpolation */
int i;
double r, bf;
/* Dark, dim, average, above average */
@@ -302,26 +321,32 @@ int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
s->F = t_F[i] * (1.0 - bf) + t_F[i+1] * bf;
} else {
/* Compute the internal parameters by category */
+ /* Fake up Lv according to category */
switch(Ev) {
case vc_dark:
s->C = 0.525;
s->Nc = 0.8;
s->F = 0.8;
+ Lv = La/0.033;
break;
case vc_dim:
s->C = 0.59;
s->Nc = 0.95;
s->F = 0.9;
+ Lv = La/0.1;
+ break;
+ case vc_average:
+ default:
+ s->C = 0.69;
+ s->Nc = 1.0;
+ s->F = 1.0;
+ Lv = La/0.2;
break;
case vc_cut_sheet:
s->C = 0.41;
s->Nc = 0.8;
s->F = 0.8;
- break;
- default: /* average */
- s->C = 0.69;
- s->Nc = 1.0;
- s->F = 1.0;
+ Lv = La/0.02; // ???
break;
}
}
@@ -331,12 +356,21 @@ int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
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->Yb = Yb > 0.005 ? Yb : 0.005; /* Set minimum to avoid divide by 0.0 */
+ s->Lv = Lv;
s->Yf = Yf;
- s->Fxyz[0] = Fxyz[0];
- s->Fxyz[1] = Fxyz[1];
- s->Fxyz[2] = Fxyz[2];
+ s->Yg = Yg;
+ if (Gxyz[0] > 0.0 && Gxyz[1] > 0.0 && Gxyz[2] > 0.0) {
+ tt = Wxyz[1]/Gxyz[1]; /* Scale to white ref white */
+ s->Gxyz[0] = tt * Gxyz[0];
+ s->Gxyz[1] = tt * Gxyz[1];
+ s->Gxyz[2] = tt * Gxyz[2];
+ } else {
+ s->Gxyz[0] = Wxyz[0];
+ s->Gxyz[1] = Wxyz[1];
+ s->Gxyz[2] = Wxyz[2];
+ }
s->hk = hk;
/* The rgba vectors */
@@ -365,10 +399,15 @@ int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
/* 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];
+ s->Fsxyz[0] = s->Yf * s->Wxyz[0];
+ s->Fsxyz[1] = s->Yf * s->Wxyz[1];
+ s->Fsxyz[2] = s->Yf * s->Wxyz[2];
+
+ /* Add in the Glare contribution from the ambient */
+ tt = s->Yg * s->La/s->Lv;
+ s->Fsxyz[0] += tt * s->Gxyz[0];
+ s->Fsxyz[1] += tt * s->Gxyz[1];
+ s->Fsxyz[2] += tt * s->Gxyz[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]);
@@ -522,7 +561,8 @@ int hk /* Flag, NZ to use Helmholtz-Kohlraush effect */
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("Glare Yg = %f\n", s->Yg);
+ printf("Glare color Gxyz = %f %f %f\n", s->Gxyz[0], s->Gxyz[1], s->Gxyz[2]);
printf("Internal parameters:\n");
printf("Surround Impact C = %f\n", s->C);
@@ -569,7 +609,7 @@ double XYZ[3]
XYZi[2] = XYZ[2];
#endif
- TRACE(("\nForward conversion:\n"))
+ TRACE(("\nCIECAM02 Forward conversion:\n"))
TRACE(("XYZ = %f %f %f\n",XYZ[0], XYZ[1], XYZ[2]))
#ifdef DISABLE_MATRIX
@@ -622,7 +662,7 @@ double XYZ[3]
/* but compressing towards white seems to be the best.) */
icmSub3(cvec, wrgb, rgbp); /* Direction of white target */
- TRACE(("rgbp %f %f %f\n", rgbp[0], rgbp[1], rgbp[2]))
+ TRACE(("ch %d, rgbp %f %f %f\n", i, rgbp[0], rgbp[1], rgbp[2]))
TRACE(("cvec %f %f %f\n", cvec[0], cvec[1], cvec[2]))
if (cvec[i] < 1e-9) { /* compression direction can't correct this coord */
@@ -632,7 +672,7 @@ double XYZ[3]
/* Scale compression vector to make it move a unit in normal direction */
icmScale3(cvec, cvec, 1.0/cvec[i]); /* Normalized vector to white */
- TRACE(("cvec %f %f %f\n", cvec[0], cvec[1], cvec[2]))
+ TRACE(("ncvec %f %f %f\n", cvec[0], cvec[1], cvec[2]))
/* Compute intersection of correction direction with this limit plane */
/* (This corresponds with finding displacement of rgbp by cvec */
@@ -971,7 +1011,7 @@ double Jab[3]
#endif
- TRACE(("\nReverse conversion:\n"))
+ TRACE(("\nCIECAM02 Reverse conversion:\n"))
TRACE(("Jab %f %f %f\n",Jab[0], Jab[1], Jab[2]))
JJ = Jab[0] * 0.01; /* J/100 */
@@ -1153,7 +1193,7 @@ double Jab[3]
#endif
-#ifdef ENABLE_COMPR
+#ifdef ENABLE_DECOMPR
/* Undo soft limiting */
{
double tt; /* Temporary */
@@ -1181,7 +1221,7 @@ double Jab[3]
/* but compressing towards white seems to be the best.) */
icmSub3(cvec, wrgb, rgbp); /* Direction of white target */
- TRACE(("rgbp %f %f %f\n", rgbp[0], rgbp[1], rgbp[2]))
+ TRACE(("ch %d, rgbp %f %f %f\n", i, rgbp[0], rgbp[1], rgbp[2]))
TRACE(("cvec %f %f %f\n", cvec[0], cvec[1], cvec[2]))
if (cvec[i] < 1e-9) { /* compression direction can't correct this coord */
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-19 19:37:07 +0000