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/* Copyright (c) 1986 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* color.c - routines for color calculations. |
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* |
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* 10/10/85 |
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*/ |
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|
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#include <stdio.h> |
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|
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#include "color.h" |
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|
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#ifdef SPEC_RGB |
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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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* each color coordinate integrates to 1. |
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*/ |
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|
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#define STARTWL 380 /* starting wavelength (nanometers) */ |
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#define INCWL 10 /* wavelength increment */ |
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#define NINC 40 /* # of values */ |
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|
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static BYTE chroma[3][NINC] = { |
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{ /* X */ |
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0, 0, 0, 2, 6, 13, 22, 30, 36, 41, |
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42, 43, 43, 44, 46, 52, 60, 71, 87, 106, |
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128, 153, 178, 200, 219, 233, 243, 249, 252, 254, |
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255 |
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}, { /* Y */ |
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0, 0, 0, 0, 0, 1, 2, 4, 7, 11, |
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17, 24, 34, 48, 64, 84, 105, 127, 148, 169, |
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188, 205, 220, 232, 240, 246, 250, 253, 254, 255, |
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255 |
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}, { /* Z */ |
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0, 0, 2, 10, 32, 66, 118, 153, 191, 220, |
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237, 246, 251, 253, 254, 255, 255, 255, 255, 255, |
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, |
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255 |
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} |
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}; |
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|
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|
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spec_rgb(col, s, e) /* comput 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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COLOR ciecolor; |
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|
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spec_cie(ciecolor, s, e); |
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cie_rgb(col, ciecolor); |
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} |
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|
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|
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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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register int i, d, r; |
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|
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s -= STARTWL; |
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if (s < 0) |
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s = 0; |
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|
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e -= STARTWL; |
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if (e >= INCWL*(NINC - 1)) |
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e = INCWL*(NINC - 1) - 1; |
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|
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d = e / INCWL; /* interpolate values */ |
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r = e % INCWL; |
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for (i = 0; i < 3; i++) |
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col[i] = chroma[i][d]*(INCWL - r) + chroma[i][d + 1]*r; |
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|
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d = s / INCWL; |
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r = s % INCWL; |
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for (i = 0; i < 3; i++) |
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col[i] -= chroma[i][d]*(INCWL - r) - chroma[i][d + 1]*r; |
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|
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col[RED] = (col[RED] + 0.5) / (256*INCWL); |
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col[GRN] = (col[GRN] + 0.5) / (256*INCWL); |
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col[BLU] = (col[BLU] + 0.5) / (256*INCWL); |
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} |
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|
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|
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cie_rgb(rgbcolor, ciecolor) /* convert CIE to RGB (NTSC) */ |
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register COLOR rgbcolor, ciecolor; |
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{ |
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static float cmat[3][3] = { |
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1.73, -.48, -.26, |
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-.81, 1.65, -.02, |
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.08, -.17, 1.28, |
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}; |
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register int i; |
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|
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for (i = 0; i < 3; i++) { |
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rgbcolor[i] = cmat[i][0]*ciecolor[0] + |
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cmat[i][1]*ciecolor[1] + |
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cmat[i][2]*ciecolor[2] ; |
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if (rgbcolor[i] < 0.0) |
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rgbcolor[i] = 0.0; |
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} |
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} |
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#endif |
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|
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|
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fwritecolrs(scanline, len, fp) /* write out a colr scanline */ |
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register COLR *scanline; |
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int len; |
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register FILE *fp; |
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{ |
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COLR lastcolr; |
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int rept; |
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|
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lastcolr[RED] = lastcolr[GRN] = lastcolr[BLU] = 1; |
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lastcolr[EXP] = 0; |
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rept = 0; |
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|
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while (len > 0) { |
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if (scanline[0][EXP] == lastcolr[EXP] && |
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scanline[0][RED] == lastcolr[RED] && |
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scanline[0][GRN] == lastcolr[GRN] && |
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scanline[0][BLU] == lastcolr[BLU]) |
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rept++; |
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else { |
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while (rept) { /* write out count */ |
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putc(1, fp); |
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putc(1, fp); |
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putc(1, fp); |
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putc(rept & 255, fp); |
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rept >>= 8; |
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} |
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putc(scanline[0][RED], fp); /* new color */ |
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putc(scanline[0][GRN], fp); |
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putc(scanline[0][BLU], fp); |
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putc(scanline[0][EXP], fp); |
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copycolr(lastcolr, scanline[0]); |
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rept = 0; |
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} |
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scanline++; |
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len--; |
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} |
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while (rept) { /* write out count */ |
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putc(1, fp); |
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putc(1, fp); |
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putc(1, fp); |
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putc(rept & 255, fp); |
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rept >>= 8; |
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} |
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return(ferror(fp) ? -1 : 0); |
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} |
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|
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|
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freadcolrs(scanline, len, fp) /* read in a colr scanline */ |
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register COLR *scanline; |
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int len; |
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register FILE *fp; |
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{ |
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int rshift; |
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register int i; |
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|
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rshift = 0; |
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|
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while (len > 0) { |
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scanline[0][RED] = getc(fp); |
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scanline[0][GRN] = getc(fp); |
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scanline[0][BLU] = getc(fp); |
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scanline[0][EXP] = getc(fp); |
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if (feof(fp) || ferror(fp)) |
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return(-1); |
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if (scanline[0][RED] == 1 && |
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scanline[0][GRN] == 1 && |
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scanline[0][BLU] == 1) { |
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for (i = scanline[0][EXP] << rshift; i > 0; i--) { |
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copycolr(scanline[0], scanline[-1]); |
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scanline++; |
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len--; |
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} |
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rshift += 8; |
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} else { |
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scanline++; |
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len--; |
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rshift = 0; |
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} |
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} |
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return(0); |
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} |
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|
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|
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fwritescan(scanline, len, fp) /* write out a scanline */ |
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register COLOR *scanline; |
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int len; |
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register FILE *fp; |
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{ |
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COLR lastcolr, thiscolr; |
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int rept; |
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|
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lastcolr[RED] = lastcolr[GRN] = lastcolr[BLU] = 1; |
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lastcolr[EXP] = 0; |
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rept = 0; |
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|
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while (len > 0) { |
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setcolr(thiscolr, scanline[0][RED], |
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scanline[0][GRN], |
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scanline[0][BLU]); |
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if (thiscolr[EXP] == lastcolr[EXP] && |
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thiscolr[RED] == lastcolr[RED] && |
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thiscolr[GRN] == lastcolr[GRN] && |
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thiscolr[BLU] == lastcolr[BLU]) |
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rept++; |
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else { |
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while (rept) { /* write out count */ |
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putc(1, fp); |
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putc(1, fp); |
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putc(1, fp); |
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putc(rept & 255, fp); |
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rept >>= 8; |
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} |
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putc(thiscolr[RED], fp); /* new color */ |
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putc(thiscolr[GRN], fp); |
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putc(thiscolr[BLU], fp); |
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putc(thiscolr[EXP], fp); |
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copycolr(lastcolr, thiscolr); |
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rept = 0; |
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} |
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scanline++; |
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len--; |
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} |
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while (rept) { /* write out count */ |
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putc(1, fp); |
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putc(1, fp); |
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putc(1, fp); |
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putc(rept & 255, fp); |
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rept >>= 8; |
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} |
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return(ferror(fp) ? -1 : 0); |
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} |
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|
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|
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freadscan(scanline, len, fp) /* read in a scanline */ |
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register COLOR *scanline; |
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int len; |
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register FILE *fp; |
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{ |
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COLR thiscolr; |
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int rshift; |
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register int i; |
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|
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rshift = 0; |
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|
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while (len > 0) { |
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thiscolr[RED] = getc(fp); |
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thiscolr[GRN] = getc(fp); |
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thiscolr[BLU] = getc(fp); |
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thiscolr[EXP] = getc(fp); |
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if (feof(fp) || ferror(fp)) |
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return(-1); |
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if (thiscolr[RED] == 1 && |
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thiscolr[GRN] == 1 && |
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thiscolr[BLU] == 1) { |
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for (i = thiscolr[EXP] << rshift; i > 0; i--) { |
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copycolor(scanline[0], scanline[-1]); |
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scanline++; |
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len--; |
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} |
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rshift += 8; |
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} else { |
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colr_color(scanline[0], thiscolr); |
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scanline++; |
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len--; |
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rshift = 0; |
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} |
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} |
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return(0); |
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} |
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|
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|
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setcolr(clr, r, g, b) /* assign a short color value */ |
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register COLR clr; |
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double r, g, b; |
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{ |
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double frexp(); |
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double d; |
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int e; |
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|
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d = r > g ? r : g; |
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if (b > d) d = b; |
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|
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if (d <= 0.0) { |
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clr[RED] = clr[GRN] = clr[BLU] = 0; |
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clr[EXP] = 0; |
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return; |
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} |
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|
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d = frexp(d, &e) * 256.0 / d; |
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|
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clr[RED] = r * d; |
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clr[GRN] = g * d; |
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clr[BLU] = b * d; |
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clr[EXP] = e + COLXS; |
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} |
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|
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|
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colr_color(col, clr) /* convert short to float color */ |
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register COLOR col; |
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register COLR clr; |
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{ |
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double ldexp(), f; |
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|
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if (clr[EXP] == 0) |
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col[RED] = col[GRN] = col[BLU] = 0.0; |
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else { |
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f = ldexp(1.0, clr[EXP]-(COLXS+8)); |
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col[RED] = (clr[RED] + 0.5)*f; |
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col[GRN] = (clr[GRN] + 0.5)*f; |
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col[BLU] = (clr[BLU] + 0.5)*f; |
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} |
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} |
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|
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|
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#ifdef FREXP |
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double |
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frexp(x, ip) /* call it paranoia, I've seen the lib version */ |
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register double x; |
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int *ip; |
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{ |
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int neg; |
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register int i; |
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|
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if (neg = (x < 0.0)) |
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x = -x; |
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else if (x == 0.0) { |
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*ip = 0; |
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return(0.0); |
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} |
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if (x < 0.5) |
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for (i = 0; x < 0.5; i--) |
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x *= 2.0; |
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else |
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for (i = 0; x >= 1.0; i++) |
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x /= 2.0; |
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*ip = i; |
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if (neg) |
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return(-x); |
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else |
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return(x); |
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} |
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#endif |
