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/* Copyright 1988 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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CLOSEST - nearest-color lookup by locally ordered search |
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we use distance in rgb space as color metric |
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Paul Heckbert |
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*/ |
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#include <stdlib.h> |
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#include "ciq.h" |
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#define inf 3*256*256 |
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static char filled[512]; /* has bucket[key] been filled yet? */ |
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static int sq[511]; |
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initializeclosest() { /* reset the buckets */ |
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static int compare(const void *a, const void *b); |
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static void fillbucket(int k); |
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void |
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initializeclosest(void) { /* reset the buckets */ |
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int k; |
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nfill = tests = calls = 0; |
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for (k=0; k<512; k++) filled[k] = 0; |
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next = space; |
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} |
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closest(r,g,b) /* find pv of colormap color closest to (r,g,b) */ |
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int r,g,b; |
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int |
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closest( /* find pv of colormap color closest to (r,g,b) */ |
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int r, |
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int g, |
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int b |
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) |
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{ |
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register struct thing *p; |
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register int *rsq,*gsq,*bsq,dist,min; |
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#define H 16 /* half-width of a bucket */ |
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compare(a,b) |
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register struct thing *a,*b; |
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static int |
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compare( |
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const void *a, |
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const void *b |
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) |
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{ |
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return a->mindist-b->mindist; |
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return ((struct thing*)a)->mindist - ((struct thing*)b)->mindist; |
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} |
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fillbucket(k) /* make list of colormap colors which could be closest */ |
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int k; /* matches for colors in bucket #k */ |
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static void |
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fillbucket( /* make list of colormap colors which could be closest */ |
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int k /* matches for colors in bucket #k */ |
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) |
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{ |
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register int r,g,b,j,dist,*rsq,*gsq,*bsq,min,best; |
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struct thing *p,*q; |
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if (!sq[0]) for (j= -255; j<256; j++) sq[j+255] = j*j; |
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r = k>>1&0xe0|H; /* center of 32x32x32 cubical bucket */ |
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g = k<<2&0xe0|H; |
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b = k<<5&0xe0|H; |
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r = (k>>1&0xe0)|H; /* center of 32x32x32 cubical bucket */ |
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g = (k<<2&0xe0)|H; |
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b = (k<<5&0xe0)|H; |
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rsq = sq+255-r; |
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gsq = sq+255-g; |
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bsq = sq+255-b; |
