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greg |
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#ifndef lint |
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greg |
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static const char RCSid[] = "$Id: ccyrgb.c,v 3.4 2012/05/17 17:11:33 greg Exp $"; |
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greg |
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#endif |
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/* |
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greg |
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* Convert MGF color to Radiance RGB and spectral representations |
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greg |
3.1 |
*/ |
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#include <stdio.h> |
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#include "color.h" |
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#include "ccolor.h" |
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void |
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ccy2rgb( /* convert MGF color to RGB */ |
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C_COLOR *cin, /* input MGF chrominance */ |
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double cieY, /* input luminance or reflectance */ |
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COLOR cout /* output RGB color */ |
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) |
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{ |
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double d; |
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COLOR xyz; |
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/* get CIE XYZ representation */ |
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c_ccvt(cin, C_CSXY); |
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d = cin->cx/cin->cy; |
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xyz[CIEX] = d * cieY; |
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xyz[CIEY] = cieY; |
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xyz[CIEZ] = (1./cin->cy - d - 1.) * cieY; |
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cie_rgb(cout, xyz); |
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} |
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/* Convert RGB to MGF color and value */ |
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double |
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rgb2ccy(COLOR cin, C_COLOR *cout) |
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{ |
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COLOR xyz; |
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double df; |
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rgb_cie(xyz, cin); |
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*cout = c_dfcolor; |
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df = xyz[CIEX] + xyz[CIEY] + xyz[CIEZ]; |
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if (df <= .0) |
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greg |
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return(.0); |
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greg |
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df = 1./df; |
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cout->cx = xyz[CIEX]*df; |
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cout->cy = xyz[CIEZ]*df; |
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cout->flags = (C_CSXY|C_CDXY); |
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return(xyz[CIEY]); |
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} |
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greg |
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void |
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ccy2scolor( /* convert MGF color, Y to spectral color */ |
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C_COLOR *cin, /* input MGF color or spectrum */ |
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double cieY, /* input luminance or reflectance */ |
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SCOLOR sco /* output spectral color */ |
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) |
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{ |
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COLORV nf, sorig[C_CNSS]; |
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int i; |
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if (cin->flags & C_CDXY || NCSAMP <= 3) { |
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COLOR col; /* tristimulus in or out, so... */ |
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ccy2rgb(cin, cieY, col); |
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setscolor(sco, colval(col,RED), colval(col,GRN), colval(col,BLU)); |
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return; |
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} |
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c_ccvt(cin, C_CSXY); |
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nf = cieY*C_CNSS/(cin->ssum*3*cin->cy); |
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for (i = C_CNSS; i--; ) /* may as well reverse order */ |
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sorig[C_CNSS-1-i] = nf*(COLORV)cin->ssamp[i]; |
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convertscolor(sco, NCSAMP, WLPART[0], WLPART[3], |
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sorig, C_CNSS, C_CMAXWL+.5*C_CWLI, C_CMINWL-.5*C_CWLI); |
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} |
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/* Convert spectral color to MGF color and Y value */ |
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double |
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scolor2ccy(SCOLOR sci, C_COLOR *cout) |
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{ |
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float hinc, cspec[MAXCSAMP]; |
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int i = NCSAMP; |
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if (i <= 3) /* defined as RGB, so... */ |
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return(rgb2ccy(sci, cout)); |
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while (i-- > 0) /* need to reverse array */ |
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cspec[i] = sci[NCSAMP-1-i]; |
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hinc = (WLPART[0]-WLPART[3])/(float)(2*NCSAMP); |
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return(c_sset(cout, WLPART[3]+hinc, WLPART[0]-hinc, cspec, NCSAMP)); |
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} |
