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/* Copyright (c) 1990 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* Convert colors and spectral ranges. |
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* Added von Kries white-balance calculations 10/01 (GW). |
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* |
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* Externals declared in color.h |
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*/ |
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#include "copyright.h" |
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#include <stdio.h> |
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#include <string.h> |
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#include "color.h" |
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#define CEPS 1e-4 /* color epsilon */ |
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RGBPRIMS stdprims = STDPRIMS; /* standard primary chromaticities */ |
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#define CEQ(v1,v2) ((v1) <= (v2)+CEPS && (v2) <= (v1)+CEPS) |
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#define XYEQ(c1,c2) (CEQ((c1)[CIEX],(c2)[CIEX]) && CEQ((c1)[CIEY],(c2)[CIEY])) |
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|
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|
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RGBPRIMS stdprims = STDPRIMS; /* standard primary chromaticities */ |
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|
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COLOR cblack = BLKCOLOR; /* global black color */ |
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COLOR cwhite = WHTCOLOR; /* global white color */ |
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|
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float xyneu[2] = {1./3., 1./3.}; /* neutral xy chromaticities */ |
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|
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/* |
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* The following table contains the CIE tristimulus integrals |
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* for X, Y, and Z. The table is cumulative, so that |
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} |
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}; |
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COLORMAT xyz2rgbmat = { /* XYZ to RGB */ |
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COLORMAT xyz2rgbmat = { /* XYZ to RGB (no white balance) */ |
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{(CIE_y_g - CIE_y_b - CIE_x_b*CIE_y_g + CIE_y_b*CIE_x_g)/CIE_C_rD, |
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(CIE_x_b - CIE_x_g - CIE_x_b*CIE_y_g + CIE_x_g*CIE_y_b)/CIE_C_rD, |
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(CIE_x_g*CIE_y_b - CIE_x_b*CIE_y_g)/CIE_C_rD}, |
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(CIE_x_r*CIE_y_g - CIE_x_g*CIE_y_r)/CIE_C_bD} |
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}; |
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COLORMAT rgb2xyzmat = { /* RGB to XYZ */ |
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COLORMAT rgb2xyzmat = { /* RGB to XYZ (no white balance) */ |
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{CIE_x_r*CIE_C_rD/CIE_D,CIE_x_g*CIE_C_gD/CIE_D,CIE_x_b*CIE_C_bD/CIE_D}, |
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{CIE_y_r*CIE_C_rD/CIE_D,CIE_y_g*CIE_C_gD/CIE_D,CIE_y_b*CIE_C_bD/CIE_D}, |
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{(1.-CIE_x_r-CIE_y_r)*CIE_C_rD/CIE_D, |
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(1.-CIE_x_b-CIE_y_b)*CIE_C_bD/CIE_D} |
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}; |
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COLORMAT vkmat = { /* Sharp primary matrix */ |
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{ 1.2694, -0.0988, -0.1706}, |
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{-0.8364, 1.8006, 0.0357}, |
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{ 0.0297, -0.0315, 1.0018} |
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}; |
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COLORMAT ivkmat = { /* inverse Sharp primary matrix */ |
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{ 0.8156, 0.0472, 0.1372}, |
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{ 0.3791, 0.5769, 0.0440}, |
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{-0.0123, 0.0167, 0.9955} |
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}; |
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void |
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spec_rgb(col, s, e) /* compute RGB color from spectral range */ |
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COLOR col; |
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int s, e; |
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} |
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void |
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spec_cie(col, s, e) /* compute a color from a spectral range */ |
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COLOR col; /* returned color */ |
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int s, e; /* starting and ending wavelengths */ |
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} |
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void |
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cie_rgb(rgb, xyz) /* convert CIE color to standard RGB */ |
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COLOR rgb; |
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COLOR xyz; |
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{ |
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colortrans(rgb, xyz2rgbmat, xyz); |
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clipgamut(rgb, xyz[CIEY], CGAMUT_LOWER, cblack, cwhite); |
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} |
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int |
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clipgamut(col, brt, gamut, lower, upper) /* clip to gamut cube */ |
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COLOR col; |
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double brt; |
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int gamut; |
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COLOR lower, upper; |
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{ |
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int rflags = 0; |
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double brtmin, brtmax, v, vv; |
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COLOR cgry; |
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register int i; |
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/* check for no check */ |
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if (gamut == 0) return(0); |
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/* check brightness limits */ |
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brtmin = 1./3.*(lower[0]+lower[1]+lower[2]); |
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if (gamut & CGAMUT_LOWER && brt < brtmin) { |
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copycolor(col, lower); |
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return(CGAMUT_LOWER); |
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} |
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brtmax = 1./3.*(upper[0]+upper[1]+upper[2]); |
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if (gamut & CGAMUT_UPPER && brt > brtmax) { |
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copycolor(col, upper); |
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return(CGAMUT_UPPER); |
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} |
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/* compute equivalent grey */ |
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v = (brt - brtmin)/(brtmax - brtmin); |
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for (i = 0; i < 3; i++) |
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cgry[i] = v*upper[i] + (1.-v)*lower[i]; |
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vv = 1.; /* check each limit */ |
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for (i = 0; i < 3; i++) |
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if (gamut & CGAMUT_LOWER && col[i] < lower[i]) { |
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v = (lower[i]+CEPS - cgry[i])/(col[i] - cgry[i]); |
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if (v < vv) vv = v; |
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rflags |= CGAMUT_LOWER; |
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} else if (gamut & CGAMUT_UPPER && col[i] > upper[i]) { |
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v = (upper[i]-CEPS - cgry[i])/(col[i] - cgry[i]); |
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if (v < vv) vv = v; |
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rflags |= CGAMUT_UPPER; |
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} |
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if (rflags) /* desaturate to cube face */ |
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for (i = 0; i < 3; i++) |
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col[i] = vv*col[i] + (1.-vv)*cgry[i]; |
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return(rflags); |
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} |
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|
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void |
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colortrans(c2, mat, c1) /* convert c1 by mat and put into c2 */ |
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register COLOR c2; |
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register COLORMAT mat; |
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register COLOR c1, c2; |
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register COLOR c1; |
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{ |
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static float cout[3]; |
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COLOR cout; |
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cout[0] = mat[0][0]*c1[0] + mat[0][1]*c1[1] + mat[0][2]*c1[2]; |
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cout[1] = mat[1][0]*c1[0] + mat[1][1]*c1[1] + mat[1][2]*c1[2]; |
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cout[2] = mat[2][0]*c1[0] + mat[2][1]*c1[1] + mat[2][2]*c1[2]; |
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if((c2[0] = cout[0]) < 0.) c2[0] = 0.; |
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if((c2[1] = cout[1]) < 0.) c2[1] = 0.; |
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if((c2[2] = cout[2]) < 0.) c2[2] = 0.; |
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copycolor(c2, cout); |
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} |
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void |
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multcolormat(m3, m2, m1) /* multiply m1 by m2 and put into m3 */ |
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COLORMAT m1, m2, m3; /* m3 can be either m1 or m2 w/o harm */ |
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COLORMAT m3; /* m3 can be either m1 or m2 w/o harm */ |
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COLORMAT m2, m1; |
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{ |
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COLORMAT mt; |
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register int i, j; |
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} |
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void |
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compxyz2rgbmat(mat, pr) /* compute conversion from CIE to RGB space */ |
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COLORMAT mat; |
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register RGBPRIMS pr; |
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} |
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void |
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comprgb2xyzmat(mat, pr) /* compute conversion from RGB to CIE space */ |
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COLORMAT mat; |
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register RGBPRIMS pr; |
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} |
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void |
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comprgb2rgbmat(mat, pr1, pr2) /* compute conversion from RGB1 to RGB2 */ |
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COLORMAT mat; |
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RGBPRIMS pr1, pr2; |
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compxyz2rgbmat(xyztopr2, pr2); |
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/* combine transforms */ |
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multcolormat(mat, pr1toxyz, xyztopr2); |
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} |
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void |
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compxyzWBmat(mat, wht1, wht2) /* CIE von Kries transform from wht1 to wht2 */ |
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COLORMAT mat; |
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float wht1[2], wht2[2]; |
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{ |
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COLOR cw1, cw2; |
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if (XYEQ(wht1,wht2)) { |
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mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
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mat[0][1] = mat[0][2] = mat[1][0] = |
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mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
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return; |
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} |
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cw1[RED] = wht1[CIEX]/wht1[CIEY]; |
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cw1[GRN] = 1.; |
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cw1[BLU] = (1. - wht1[CIEX] - wht1[CIEY])/wht1[CIEY]; |
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colortrans(cw1, vkmat, cw1); |
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cw2[RED] = wht2[CIEX]/wht2[CIEY]; |
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cw2[GRN] = 1.; |
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cw2[BLU] = (1. - wht2[CIEX] - wht2[CIEY])/wht2[CIEY]; |
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colortrans(cw2, vkmat, cw2); |
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mat[0][0] = cw2[RED]/cw1[RED]; |
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mat[1][1] = cw2[GRN]/cw1[GRN]; |
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mat[2][2] = cw2[BLU]/cw1[BLU]; |
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mat[0][1] = mat[0][2] = mat[1][0] = |
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mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
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multcolormat(mat, vkmat, mat); |
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multcolormat(mat, mat, ivkmat); |
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} |
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|
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void |
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compxyz2rgbWBmat(mat, pr) /* von Kries conversion from CIE to RGB space */ |
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COLORMAT mat; |
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RGBPRIMS pr; |
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{ |
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COLORMAT wbmat; |
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compxyz2rgbmat(mat, pr); |
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if (XYEQ(pr[WHT],xyneu)) |
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return; |
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compxyzWBmat(wbmat, xyneu, pr[WHT]); |
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multcolormat(mat, wbmat, mat); |
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} |
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|
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void |
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comprgb2xyzWBmat(mat, pr) /* von Kries conversion from RGB to CIE space */ |
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COLORMAT mat; |
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RGBPRIMS pr; |
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{ |
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COLORMAT wbmat; |
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comprgb2xyzmat(mat, pr); |
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if (XYEQ(pr[WHT],xyneu)) |
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return; |
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compxyzWBmat(wbmat, pr[WHT], xyneu); |
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multcolormat(mat, mat, wbmat); |
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} |
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|
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void |
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comprgb2rgbWBmat(mat, pr1, pr2) /* von Kries conversion from RGB1 to RGB2 */ |
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COLORMAT mat; |
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RGBPRIMS pr1, pr2; |
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{ |
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COLORMAT pr1toxyz, xyztopr2, wbmat; |
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|
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if (pr1 == pr2) { |
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mat[0][0] = mat[1][1] = mat[2][2] = 1.0; |
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mat[0][1] = mat[0][2] = mat[1][0] = |
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mat[1][2] = mat[2][0] = mat[2][1] = 0.0; |
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return; |
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} |
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comprgb2xyzmat(pr1toxyz, pr1); |
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compxyzWBmat(wbmat, pr1[WHT], pr2[WHT]); |
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compxyz2rgbmat(xyztopr2, pr2); |
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/* combine transforms */ |
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multcolormat(mat, pr1toxyz, wbmat); |
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multcolormat(mat, mat, xyztopr2); |
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} |