--- ray/src/common/spec_rgb.c	1991/11/12 16:54:40	2.1
+++ ray/src/common/spec_rgb.c	2003/06/30 19:04:29	2.13
@@ -1,15 +1,33 @@
-/* Copyright (c) 1990 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: spec_rgb.c,v 2.13 2003/06/30 19:04:29 greg Exp $";
 #endif
-
 /*
  * Convert colors and spectral ranges.
+ * Added von Kries white-balance calculations 10/01 (GW).
+ *
+ * Externals declared in color.h
  */
 
+#include "copyright.h"
+
+#include <stdio.h>
+#include <string.h>
 #include "color.h"
 
+#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
@@ -39,22 +57,40 @@ static BYTE  chroma[3][NINC] = {
 	}
 };
 
-#ifdef  NTSC
-static float  xyz2rgbmat[3][3] = {	/* XYZ to RGB (NTSC) */
-	1.73, -.48, -.26,
-	-.81, 1.65, -.02,
-	 .08, -.17, 1.28,
+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}
 };
-#else
-static float xyz2rgbmat[3][3] = {	/* XYZ to RGB (color monitor) */
-	 2.739, -1.145, -.424,
-	-1.119,  2.029,  .033,
-	  .138,  -.333, 1.105,
+
+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}
 };
-#endif
 
+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;
@@ -66,6 +102,7 @@ int  s, e;
 }
 
 
+void
 spec_cie(col, s, e)		/* compute a color from a spectral range */
 COLOR  col;		/* returned color */
 int  s, e;		/* starting and ending wavelengths */
@@ -78,7 +115,7 @@ int  s, e;		/* starting and ending wavelengths */
 
 	e -= STARTWL;
 	if (e <= s) {
-		col[RED] = col[GRN] = col[BLU] = 0.0;
+		col[CIEX] = col[CIEY] = col[CIEZ] = 0.0;
 		return;
 	}
 	if (e >= INCWL*(NINC - 1))
@@ -94,22 +131,285 @@ int  s, e;		/* starting and ending wavelengths */
 	for (i = 0; i < 3; i++)
 		col[i] -= chroma[i][d]*(INCWL - r) - chroma[i][d + 1]*r;
 
-	col[RED] = (col[RED] + 0.5) / (256*INCWL);
-	col[GRN] = (col[GRN] + 0.5) / (256*INCWL);
-	col[BLU] = (col[BLU] + 0.5) / (256*INCWL);
+	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));
 }
 
 
-cie_rgb(rgbcolor, ciecolor)		/* convert CIE to RGB */
-register COLOR  rgbcolor, ciecolor;
+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);
+}
 
-	for (i = 0; i < 3; i++) {
-		rgbcolor[i] =	xyz2rgbmat[i][0]*ciecolor[0] +
-				xyz2rgbmat[i][1]*ciecolor[1] +
-				xyz2rgbmat[i][2]*ciecolor[2] ;
-		if (rgbcolor[i] < 0.0)
-			rgbcolor[i] = 0.0;
+
+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);
 }