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/* Copyright (c) 1992 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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* pf3.c - routines for gaussian and box filtering |
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* |
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* 8/13/86 |
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*/ |
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|
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#include <stdio.h> |
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|
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#include <math.h> |
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|
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#include "color.h" |
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|
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#define FTINY 1e-7 |
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|
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extern double rad; /* output pixel radius for filtering */ |
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|
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extern int nrows; /* number of rows for output */ |
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extern int ncols; /* number of columns for output */ |
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|
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extern int boxfilt; /* do box filtering? */ |
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|
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extern int xres, yres; /* resolution of input */ |
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|
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extern double x_c, y_r; /* conversion factors */ |
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|
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extern int xrad; /* x window size */ |
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extern int yrad; /* y window size */ |
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|
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extern int barsize; /* size of input scan bar */ |
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extern COLOR **scanin; /* input scan bar */ |
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extern COLOR *scanout; /* output scan line */ |
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|
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extern char *progname; |
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|
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float *gausstable; /* gauss lookup table */ |
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|
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#define lookgauss(x) gausstable[(int)(10.*(x)+.5)] |
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|
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|
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initmask() /* initialize gaussian lookup table */ |
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{ |
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extern char *malloc(); |
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double d; |
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register int x; |
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|
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gausstable = (float *)malloc(100*sizeof(float)); |
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if (gausstable == NULL) { |
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fprintf(stderr, "%s: out of memory in initmask\n", progname); |
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quit(1); |
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} |
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d = x_c*y_r*0.25/rad/rad; |
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gausstable[0] = exp(-d)/sqrt(d); |
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for (x = 1; x < 100; x++) |
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if ((gausstable[x] = exp(-x*0.1)/sqrt(x*0.1)) > gausstable[0]) |
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gausstable[x] = gausstable[0]; |
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} |
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|
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|
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dobox(csum, xcent, ycent, c, r) /* simple box filter */ |
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COLOR csum; |
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int xcent, ycent; |
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int c, r; |
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{ |
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int wsum; |
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double d; |
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int y; |
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register int x; |
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register COLOR *scan; |
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|
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wsum = 0; |
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setcolor(csum, 0.0, 0.0, 0.0); |
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for (y = ycent+1-yrad; y <= ycent+yrad; y++) { |
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if (y < 0) continue; |
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if (y >= yres) break; |
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d = y_r < 1.0 ? y_r*y - r : (double)(y - ycent); |
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if (d > 0.5+FTINY || d < -0.5-FTINY) |
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continue; |
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scan = scanin[y%barsize]; |
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for (x = xcent+1-xrad; x <= xcent+xrad; x++) { |
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if (x < 0) continue; |
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if (x >= xres) break; |
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d = x_c < 1.0 ? x_c*x - c : (double)(x - xcent); |
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if (d > 0.5+FTINY || d < -0.5-FTINY) |
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continue; |
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wsum++; |
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addcolor(csum, scan[x]); |
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} |
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} |
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if (wsum > 1) |
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scalecolor(csum, 1.0/wsum); |
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} |
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|
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|
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dogauss(csum, xcent, ycent, c, r) /* gaussian filter */ |
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COLOR csum; |
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int xcent, ycent; |
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int c, r; |
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{ |
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double dy, dx, weight, wsum; |
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COLOR ctmp; |
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int y; |
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register int x; |
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register COLOR *scan; |
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|
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wsum = FTINY; |
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setcolor(csum, 0.0, 0.0, 0.0); |
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for (y = ycent-yrad; y <= ycent+yrad; y++) { |
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if (y < 0) continue; |
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if (y >= yres) break; |
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dy = (y_r*(y+.5) - (r+.5))/rad; |
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scan = scanin[y%barsize]; |
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for (x = xcent-xrad; x <= xcent+xrad; x++) { |
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if (x < 0) continue; |
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if (x >= xres) break; |
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dx = (x_c*(x+.5) - (c+.5))/rad; |
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weight = lookgauss(dx*dx + dy*dy); |
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wsum += weight; |
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copycolor(ctmp, scan[x]); |
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scalecolor(ctmp, weight); |
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addcolor(csum, ctmp); |
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} |
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} |
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scalecolor(csum, 1.0/wsum); |
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} |
