#ifndef lint
static const char RCSid[] = "$Id: spec_rgb.c,v 2.11 2003/02/22 02:07:22 greg Exp $";
#endif
/*
* Convert colors and spectral ranges.
* Added von Kries white-balance calculations 10/01 (GW).
*
* Externals declared in color.h
*/
/* ====================================================================
* The Radiance Software License, Version 1.0
*
* Copyright (c) 1990 - 2002 The Regents of the University of California,
* through Lawrence Berkeley National Laboratory. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes Radiance software
* (http://radsite.lbl.gov/)
* developed by the Lawrence Berkeley National Laboratory
* (http://www.lbl.gov/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
* and "The Regents of the University of California" must
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* 5. Products derived from this software may not be called "Radiance",
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* permission of Lawrence Berkeley National Laboratory.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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*
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*/
#include "color.h"
#include
#define CEPS 1e-4 /* color epsilon */
#define CEQ(v1,v2) ((v1) <= (v2)+CEPS && (v2) <= (v1)+CEPS)
#define XYEQ(c1,c2) (CEQ((c1)[CIEX],(c2)[CIEX]) && CEQ((c1)[CIEY],(c2)[CIEY]))
RGBPRIMS stdprims = STDPRIMS; /* standard primary chromaticities */
COLOR cblack = BLKCOLOR; /* global black color */
COLOR cwhite = WHTCOLOR; /* global white color */
float xyneu[2] = {1./3., 1./3.}; /* neutral xy chromaticities */
/*
* The following table contains the CIE tristimulus integrals
* for X, Y, and Z. The table is cumulative, so that
* each color coordinate integrates to 1.
*/
#define STARTWL 380 /* starting wavelength (nanometers) */
#define INCWL 10 /* wavelength increment */
#define NINC 40 /* # of values */
static BYTE chroma[3][NINC] = {
{ /* X */
0, 0, 0, 2, 6, 13, 22, 30, 36, 41,
42, 43, 43, 44, 46, 52, 60, 71, 87, 106,
128, 153, 178, 200, 219, 233, 243, 249, 252, 254,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255
}, { /* Y */
0, 0, 0, 0, 0, 1, 2, 4, 7, 11,
17, 24, 34, 48, 64, 84, 105, 127, 148, 169,
188, 205, 220, 232, 240, 246, 250, 253, 254, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255
}, { /* Z */
0, 0, 2, 10, 32, 66, 118, 153, 191, 220,
237, 246, 251, 253, 254, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255
}
};
COLORMAT xyz2rgbmat = { /* XYZ to RGB (no white balance) */
{(CIE_y_g - CIE_y_b - CIE_x_b*CIE_y_g + CIE_y_b*CIE_x_g)/CIE_C_rD,
(CIE_x_b - CIE_x_g - CIE_x_b*CIE_y_g + CIE_x_g*CIE_y_b)/CIE_C_rD,
(CIE_x_g*CIE_y_b - CIE_x_b*CIE_y_g)/CIE_C_rD},
{(CIE_y_b - CIE_y_r - CIE_y_b*CIE_x_r + CIE_y_r*CIE_x_b)/CIE_C_gD,
(CIE_x_r - CIE_x_b - CIE_x_r*CIE_y_b + CIE_x_b*CIE_y_r)/CIE_C_gD,
(CIE_x_b*CIE_y_r - CIE_x_r*CIE_y_b)/CIE_C_gD},
{(CIE_y_r - CIE_y_g - CIE_y_r*CIE_x_g + CIE_y_g*CIE_x_r)/CIE_C_bD,
(CIE_x_g - CIE_x_r - CIE_x_g*CIE_y_r + CIE_x_r*CIE_y_g)/CIE_C_bD,
(CIE_x_r*CIE_y_g - CIE_x_g*CIE_y_r)/CIE_C_bD}
};
COLORMAT rgb2xyzmat = { /* RGB to XYZ (no white balance) */
{CIE_x_r*CIE_C_rD/CIE_D,CIE_x_g*CIE_C_gD/CIE_D,CIE_x_b*CIE_C_bD/CIE_D},
{CIE_y_r*CIE_C_rD/CIE_D,CIE_y_g*CIE_C_gD/CIE_D,CIE_y_b*CIE_C_bD/CIE_D},
{(1.-CIE_x_r-CIE_y_r)*CIE_C_rD/CIE_D,
(1.-CIE_x_g-CIE_y_g)*CIE_C_gD/CIE_D,
(1.-CIE_x_b-CIE_y_b)*CIE_C_bD/CIE_D}
};
COLORMAT vkmat = { /* Sharp primary matrix */
{ 1.2694, -0.0988, -0.1706},
{-0.8364, 1.8006, 0.0357},
{ 0.0297, -0.0315, 1.0018}
};
COLORMAT ivkmat = { /* inverse Sharp primary matrix */
{ 0.8156, 0.0472, 0.1372},
{ 0.3791, 0.5769, 0.0440},
{-0.0123, 0.0167, 0.9955}
};
void
spec_rgb(col, s, e) /* compute RGB color from spectral range */
COLOR col;
int s, e;
{
COLOR ciecolor;
spec_cie(ciecolor, s, e);
cie_rgb(col, ciecolor);
}
void
spec_cie(col, s, e) /* compute a color from a spectral range */
COLOR col; /* returned color */
int s, e; /* starting and ending wavelengths */
{
register int i, d, r;
s -= STARTWL;
if (s < 0)
s = 0;
e -= STARTWL;
if (e <= s) {
col[CIEX] = col[CIEY] = col[CIEZ] = 0.0;
return;
}
if (e >= INCWL*(NINC - 1))
e = INCWL*(NINC - 1) - 1;
d = e / INCWL; /* interpolate values */
r = e % INCWL;
for (i = 0; i < 3; i++)
col[i] = chroma[i][d]*(INCWL - r) + chroma[i][d + 1]*r;
d = s / INCWL;
r = s % INCWL;
for (i = 0; i < 3; i++)
col[i] -= chroma[i][d]*(INCWL - r) - chroma[i][d + 1]*r;
col[CIEX] = (col[CIEX] + 0.5) * (1./(256*INCWL));
col[CIEY] = (col[CIEY] + 0.5) * (1./(256*INCWL));
col[CIEZ] = (col[CIEZ] + 0.5) * (1./(256*INCWL));
}
void
cie_rgb(rgb, xyz) /* convert CIE color to standard RGB */
COLOR rgb;
COLOR xyz;
{
colortrans(rgb, xyz2rgbmat, xyz);
clipgamut(rgb, xyz[CIEY], CGAMUT_LOWER, cblack, cwhite);
}
int
clipgamut(col, brt, gamut, lower, upper) /* clip to gamut cube */
COLOR col;
double brt;
int gamut;
COLOR lower, upper;
{
int rflags = 0;
double brtmin, brtmax, v, vv;
COLOR cgry;
register int i;
/* check for no check */
if (gamut == 0) return(0);
/* check brightness limits */
brtmin = 1./3.*(lower[0]+lower[1]+lower[2]);
if (gamut & CGAMUT_LOWER && brt < brtmin) {
copycolor(col, lower);
return(CGAMUT_LOWER);
}
brtmax = 1./3.*(upper[0]+upper[1]+upper[2]);
if (gamut & CGAMUT_UPPER && brt > brtmax) {
copycolor(col, upper);
return(CGAMUT_UPPER);
}
/* compute equivalent grey */
v = (brt - brtmin)/(brtmax - brtmin);
for (i = 0; i < 3; i++)
cgry[i] = v*upper[i] + (1.-v)*lower[i];
vv = 1.; /* check each limit */
for (i = 0; i < 3; i++)
if (gamut & CGAMUT_LOWER && col[i] < lower[i]) {
v = (lower[i]+CEPS - cgry[i])/(col[i] - cgry[i]);
if (v < vv) vv = v;
rflags |= CGAMUT_LOWER;
} else if (gamut & CGAMUT_UPPER && col[i] > upper[i]) {
v = (upper[i]-CEPS - cgry[i])/(col[i] - cgry[i]);
if (v < vv) vv = v;
rflags |= CGAMUT_UPPER;
}
if (rflags) /* desaturate to cube face */
for (i = 0; i < 3; i++)
col[i] = vv*col[i] + (1.-vv)*cgry[i];
return(rflags);
}
void
colortrans(c2, mat, c1) /* convert c1 by mat and put into c2 */
register COLOR c2;
register COLORMAT mat;
register COLOR c1;
{
COLOR cout;
cout[0] = mat[0][0]*c1[0] + mat[0][1]*c1[1] + mat[0][2]*c1[2];
cout[1] = mat[1][0]*c1[0] + mat[1][1]*c1[1] + mat[1][2]*c1[2];
cout[2] = mat[2][0]*c1[0] + mat[2][1]*c1[1] + mat[2][2]*c1[2];
copycolor(c2, cout);
}
void
multcolormat(m3, m2, m1) /* multiply m1 by m2 and put into m3 */
COLORMAT m3; /* m3 can be either m1 or m2 w/o harm */
COLORMAT m2, m1;
{
COLORMAT mt;
register int i, j;
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
mt[i][j] = m1[i][0]*m2[0][j] +
m1[i][1]*m2[1][j] +
m1[i][2]*m2[2][j] ;
cpcolormat(m3, mt);
}
void
compxyz2rgbmat(mat, pr) /* compute conversion from CIE to RGB space */
COLORMAT mat;
register RGBPRIMS pr;
{
double C_rD, C_gD, C_bD;
if (pr == stdprims) { /* can use xyz2rgbmat */
cpcolormat(mat, xyz2rgbmat);
return;
}
C_rD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) -
pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) +
pr[GRN][CIEX]*pr[BLU][CIEY] - pr[BLU][CIEX]*pr[GRN][CIEY] ) ;
C_gD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) -
pr[WHT][CIEY]*(pr[BLU][CIEX] - pr[RED][CIEX]) -
pr[RED][CIEX]*pr[BLU][CIEY] + pr[BLU][CIEX]*pr[RED][CIEY] ) ;
C_bD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) -
pr[WHT][CIEY]*(pr[RED][CIEX] - pr[GRN][CIEX]) +
pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ;
mat[0][0] = (pr[GRN][CIEY] - pr[BLU][CIEY] -
pr[BLU][CIEX]*pr[GRN][CIEY] +
pr[BLU][CIEY]*pr[GRN][CIEX])/C_rD ;
mat[0][1] = (pr[BLU][CIEX] - pr[GRN][CIEX] -
pr[BLU][CIEX]*pr[GRN][CIEY] +
pr[GRN][CIEX]*pr[BLU][CIEY])/C_rD ;
mat[0][2] = (pr[GRN][CIEX]*pr[BLU][CIEY] -
pr[BLU][CIEX]*pr[GRN][CIEY])/C_rD ;
mat[1][0] = (pr[BLU][CIEY] - pr[RED][CIEY] -
pr[BLU][CIEY]*pr[RED][CIEX] +
pr[RED][CIEY]*pr[BLU][CIEX])/C_gD ;
mat[1][1] = (pr[RED][CIEX] - pr[BLU][CIEX] -
pr[RED][CIEX]*pr[BLU][CIEY] +
pr[BLU][CIEX]*pr[RED][CIEY])/C_gD ;
mat[1][2] = (pr[BLU][CIEX]*pr[RED][CIEY] -
pr[RED][CIEX]*pr[BLU][CIEY])/C_gD ;
mat[2][0] = (pr[RED][CIEY] - pr[GRN][CIEY] -
pr[RED][CIEY]*pr[GRN][CIEX] +
pr[GRN][CIEY]*pr[RED][CIEX])/C_bD ;
mat[2][1] = (pr[GRN][CIEX] - pr[RED][CIEX] -
pr[GRN][CIEX]*pr[RED][CIEY] +
pr[RED][CIEX]*pr[GRN][CIEY])/C_bD ;
mat[2][2] = (pr[RED][CIEX]*pr[GRN][CIEY] -
pr[GRN][CIEX]*pr[RED][CIEY])/C_bD ;
}
void
comprgb2xyzmat(mat, pr) /* compute conversion from RGB to CIE space */
COLORMAT mat;
register RGBPRIMS pr;
{
double C_rD, C_gD, C_bD, D;
if (pr == stdprims) { /* can use rgb2xyzmat */
cpcolormat(mat, rgb2xyzmat);
return;
}
C_rD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) -
pr[WHT][CIEY]*(pr[GRN][CIEX] - pr[BLU][CIEX]) +
pr[GRN][CIEX]*pr[BLU][CIEY] - pr[BLU][CIEX]*pr[GRN][CIEY] ) ;
C_gD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) -
pr[WHT][CIEY]*(pr[BLU][CIEX] - pr[RED][CIEX]) -
pr[RED][CIEX]*pr[BLU][CIEY] + pr[BLU][CIEX]*pr[RED][CIEY] ) ;
C_bD = (1./pr[WHT][CIEY]) *
( pr[WHT][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) -
pr[WHT][CIEY]*(pr[RED][CIEX] - pr[GRN][CIEX]) +
pr[RED][CIEX]*pr[GRN][CIEY] - pr[GRN][CIEX]*pr[RED][CIEY] ) ;
D = pr[RED][CIEX]*(pr[GRN][CIEY] - pr[BLU][CIEY]) +
pr[GRN][CIEX]*(pr[BLU][CIEY] - pr[RED][CIEY]) +
pr[BLU][CIEX]*(pr[RED][CIEY] - pr[GRN][CIEY]) ;
mat[0][0] = pr[RED][CIEX]*C_rD/D;
mat[0][1] = pr[GRN][CIEX]*C_gD/D;
mat[0][2] = pr[BLU][CIEX]*C_bD/D;
mat[1][0] = pr[RED][CIEY]*C_rD/D;
mat[1][1] = pr[GRN][CIEY]*C_gD/D;
mat[1][2] = pr[BLU][CIEY]*C_bD/D;
mat[2][0] = (1.-pr[RED][CIEX]-pr[RED][CIEY])*C_rD/D;
mat[2][1] = (1.-pr[GRN][CIEX]-pr[GRN][CIEY])*C_gD/D;
mat[2][2] = (1.-pr[BLU][CIEX]-pr[BLU][CIEY])*C_bD/D;
}
void
comprgb2rgbmat(mat, pr1, pr2) /* compute conversion from RGB1 to RGB2 */
COLORMAT mat;
RGBPRIMS pr1, pr2;
{
COLORMAT pr1toxyz, xyztopr2;
if (pr1 == pr2) {
mat[0][0] = mat[1][1] = mat[2][2] = 1.0;
mat[0][1] = mat[0][2] = mat[1][0] =
mat[1][2] = mat[2][0] = mat[2][1] = 0.0;
return;
}
comprgb2xyzmat(pr1toxyz, pr1);
compxyz2rgbmat(xyztopr2, pr2);
/* combine transforms */
multcolormat(mat, pr1toxyz, xyztopr2);
}
void
compxyzWBmat(mat, wht1, wht2) /* CIE von Kries transform from wht1 to wht2 */
COLORMAT mat;
float wht1[2], wht2[2];
{
COLOR cw1, cw2;
if (XYEQ(wht1,wht2)) {
mat[0][0] = mat[1][1] = mat[2][2] = 1.0;
mat[0][1] = mat[0][2] = mat[1][0] =
mat[1][2] = mat[2][0] = mat[2][1] = 0.0;
return;
}
cw1[RED] = wht1[CIEX]/wht1[CIEY];
cw1[GRN] = 1.;
cw1[BLU] = (1. - wht1[CIEX] - wht1[CIEY])/wht1[CIEY];
colortrans(cw1, vkmat, cw1);
cw2[RED] = wht2[CIEX]/wht2[CIEY];
cw2[GRN] = 1.;
cw2[BLU] = (1. - wht2[CIEX] - wht2[CIEY])/wht2[CIEY];
colortrans(cw2, vkmat, cw2);
mat[0][0] = cw2[RED]/cw1[RED];
mat[1][1] = cw2[GRN]/cw1[GRN];
mat[2][2] = cw2[BLU]/cw1[BLU];
mat[0][1] = mat[0][2] = mat[1][0] =
mat[1][2] = mat[2][0] = mat[2][1] = 0.0;
multcolormat(mat, vkmat, mat);
multcolormat(mat, mat, ivkmat);
}
void
compxyz2rgbWBmat(mat, pr) /* von Kries conversion from CIE to RGB space */
COLORMAT mat;
RGBPRIMS pr;
{
COLORMAT wbmat;
compxyz2rgbmat(mat, pr);
if (XYEQ(pr[WHT],xyneu))
return;
compxyzWBmat(wbmat, xyneu, pr[WHT]);
multcolormat(mat, wbmat, mat);
}
void
comprgb2xyzWBmat(mat, pr) /* von Kries conversion from RGB to CIE space */
COLORMAT mat;
RGBPRIMS pr;
{
COLORMAT wbmat;
comprgb2xyzmat(mat, pr);
if (XYEQ(pr[WHT],xyneu))
return;
compxyzWBmat(wbmat, pr[WHT], xyneu);
multcolormat(mat, mat, wbmat);
}
void
comprgb2rgbWBmat(mat, pr1, pr2) /* von Kries conversion from RGB1 to RGB2 */
COLORMAT mat;
RGBPRIMS pr1, pr2;
{
COLORMAT pr1toxyz, xyztopr2, wbmat;
if (pr1 == pr2) {
mat[0][0] = mat[1][1] = mat[2][2] = 1.0;
mat[0][1] = mat[0][2] = mat[1][0] =
mat[1][2] = mat[2][0] = mat[2][1] = 0.0;
return;
}
comprgb2xyzmat(pr1toxyz, pr1);
compxyzWBmat(wbmat, pr1[WHT], pr2[WHT]);
compxyz2rgbmat(xyztopr2, pr2);
/* combine transforms */
multcolormat(mat, pr1toxyz, wbmat);
multcolormat(mat, mat, xyztopr2);
}