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#ifndef lint |
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static const char RCSid[] = "$Id: pf3.c,v 2.15 2003/02/25 00:26:05 greg Exp $"; |
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#endif |
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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 "standard.h" |
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|
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#include <string.h> |
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|
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#include "color.h" |
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|
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#define RSCA 1.13 /* square-radius multiplier: sqrt(4/PI) */ |
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#define TEPS 0.2 /* threshold proximity goal */ |
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#define REPS 0.1 /* radius proximity goal */ |
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|
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extern double CHECKRAD; /* radius over which gaussian is summed */ |
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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 double thresh; /* maximum contribution for subpixel */ |
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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 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 search radius */ |
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extern int yrad; /* y search radius */ |
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extern int xbrad; /* x box size */ |
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extern int ybrad; /* y box 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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extern COLOR **scoutbar; /* output scan bar (if thresh > 0) */ |
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extern float **greybar; /* grey-averaged input values */ |
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extern int obarsize; /* size of output scan bar */ |
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extern int orad; /* output window radius */ |
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|
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extern int wrapfilt; /* wrap filter horizontally? */ |
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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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float *ringsum; /* sum of ring values */ |
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short *ringwt; /* weight (count) of ring values */ |
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short *ringndx; /* ring index table */ |
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float *warr; /* array of pixel weights */ |
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|
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extern double (*ourbright)(); /* brightness computation function */ |
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|
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double pickfilt(); |
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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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int gtabsiz; |
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double gaussN; |
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double d; |
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register int x; |
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|
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gtabsiz = 111*CHECKRAD*CHECKRAD; |
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gausstable = (float *)malloc(gtabsiz*sizeof(float)); |
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if (gausstable == NULL) |
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goto memerr; |
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d = x_c*y_r*0.25/(rad*rad); |
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gausstable[0] = exp(-d); |
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for (x = 1; x < gtabsiz; x++) |
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if (x*0.1 <= d) |
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gausstable[x] = gausstable[0]; |
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else |
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gausstable[x] = exp(-x*0.1); |
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if (obarsize == 0) |
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return; |
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/* compute integral of filter */ |
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gaussN = PI*d*exp(-d); /* plateau */ |
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for (d = sqrt(d)+0.05; d <= RSCA*CHECKRAD; d += 0.1) |
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gaussN += 0.1*2.0*PI*d*exp(-d*d); |
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/* normalize filter */ |
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gaussN = x_c*y_r/(rad*rad*gaussN); |
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for (x = 0; x < gtabsiz; x++) |
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gausstable[x] *= gaussN; |
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/* create ring averages table */ |
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ringndx = (short *)malloc((2*orad*orad+1)*sizeof(short)); |
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if (ringndx == NULL) |
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goto memerr; |
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for (x = 2*orad*orad+1; --x > orad*orad; ) |
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ringndx[x] = -1; |
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do |
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ringndx[x] = sqrt((double)x); |
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while (x--); |
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ringsum = (float *)malloc((orad+1)*sizeof(float)); |
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ringwt = (short *)malloc((orad+1)*sizeof(short)); |
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warr = (float *)malloc(obarsize*obarsize*sizeof(float)); |
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if (ringsum == NULL | ringwt == 0 | warr == NULL) |
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goto memerr; |
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return; |
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memerr: |
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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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|
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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, offs; |
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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-ybrad; y <= ycent+ybrad; 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+.5) : (double)(y - ycent); |
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if (d < -0.5) continue; |
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if (d >= 0.5) break; |
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scan = scanin[y%barsize]; |
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for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) { |
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offs = x < 0 ? xres : x >= xres ? -xres : 0; |
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if (offs && !wrapfilt) |
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continue; |
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d = x_c < 1.0 ? x_c*x - (c+.5) : (double)(x - xcent); |
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if (d < -0.5) continue; |
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if (d >= 0.5) break; |
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wsum++; |
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addcolor(csum, scan[x+offs]); |
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} |
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} |
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if (wsum > 1) { |
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d = 1.0/wsum; |
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scalecolor(csum, d); |
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} |
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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, offs; |
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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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offs = x < 0 ? xres : x >= xres ? -xres : 0; |
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if (offs && !wrapfilt) |
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continue; |
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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+offs]); |
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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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weight = 1.0/wsum; |
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scalecolor(csum, weight); |
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} |
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|
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|
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dothresh(xcent, ycent, ccent, rcent) /* gaussian threshold filter */ |
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int xcent, ycent; |
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int ccent, rcent; |
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{ |
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double d; |
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int r, y, offs; |
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register int c, x; |
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register float *gscan; |
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/* compute ring sums */ |
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memset((char *)ringsum, '\0', (orad+1)*sizeof(float)); |
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memset((char *)ringwt, '\0', (orad+1)*sizeof(short)); |
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for (r = -orad; r <= orad; r++) { |
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if (rcent+r < 0) continue; |
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if (rcent+r >= nrows) break; |
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gscan = greybar[(rcent+r)%obarsize]; |
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for (c = -orad; c <= orad; c++) { |
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offs = ccent+c < 0 ? ncols : |
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ccent+c >= ncols ? -ncols : 0; |
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if (offs && !wrapfilt) |
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continue; |
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x = ringndx[c*c + r*r]; |
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if (x < 0) continue; |
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ringsum[x] += gscan[ccent+c+offs]; |
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ringwt[x]++; |
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} |
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} |
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/* filter each subpixel */ |
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for (y = ycent+1-ybrad; y <= ycent+ybrad; 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 - (rcent+.5) : (double)(y - ycent); |
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if (d < -0.5) continue; |
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if (d >= 0.5) break; |
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for (x = xcent+1-xbrad; x <= xcent+xbrad; x++) { |
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offs = x < 0 ? xres : x >= xres ? -xres : 0; |
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if (offs && !wrapfilt) |
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continue; |
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d = x_c < 1.0 ? x_c*x - (ccent+.5) : (double)(x - xcent); |
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if (d < -0.5) continue; |
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if (d >= 0.5) break; |
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sumans(x, y, rcent, ccent, |
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pickfilt((*ourbright)(scanin[y%barsize][x+offs]))); |
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} |
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} |
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} |
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|
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|
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double |
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pickfilt(p0) /* find filter multiplier for p0 */ |
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double p0; |
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{ |
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double m = 1.0; |
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double t, num, denom, avg, wsum; |
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double mlimit[2]; |
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int ilimit = 4.0/TEPS; |
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register int i; |
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/* iterative search for m */ |
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mlimit[0] = 1.0; mlimit[1] = orad/rad/CHECKRAD; |
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do { |
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/* compute grey weighted average */ |
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i = RSCA*CHECKRAD*rad*m + .5; |
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if (i > orad) i = orad; |
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avg = wsum = 0.0; |
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while (i--) { |
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t = (i+.5)/(m*rad); |
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t = lookgauss(t*t); |
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avg += t*ringsum[i]; |
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wsum += t*ringwt[i]; |
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} |
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if (avg < 1e-20) /* zero inclusive average */ |
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return(1.0); |
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avg /= wsum; |
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/* check threshold */ |
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denom = m*m/gausstable[0] - p0/avg; |
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if (denom <= FTINY) { /* zero exclusive average */ |
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if (m >= mlimit[1]-REPS) |
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break; |
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m = mlimit[1]; |
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continue; |
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} |
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num = p0/avg - 1.0; |
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if (num < 0.0) num = -num; |
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t = num/denom; |
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if (t <= thresh) { |
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if (m <= mlimit[0]+REPS || (thresh-t)/thresh <= TEPS) |
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break; |
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} else { |
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if (m >= mlimit[1]-REPS || (t-thresh)/thresh <= TEPS) |
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break; |
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} |
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t = m; /* remember current m */ |
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/* next guesstimate */ |
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m = sqrt(gausstable[0]*(num/thresh + p0/avg)); |
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if (m < t) { /* bound it */ |
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if (m <= mlimit[0]+FTINY) |
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m = 0.5*(mlimit[0] + t); |
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mlimit[1] = t; |
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} else { |
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if (m >= mlimit[1]-FTINY) |
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m = 0.5*(mlimit[1] + t); |
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mlimit[0] = t; |
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} |
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} while (--ilimit > 0); |
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return(m); |
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} |
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|
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|
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sumans(px, py, rcent, ccent, m) /* sum input pixel to output */ |
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int px, py; |
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int rcent, ccent; |
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double m; |
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{ |
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double dy2, dx; |
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COLOR pval, ctmp; |
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int ksiz, r, offs; |
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double pc, pr, norm; |
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register int i, c; |
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register COLOR *scan; |
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/* |
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* This normalization method fails at the picture borders because |
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* a different number of input pixels contribute there. |
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*/ |
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scan = scanin[py%barsize] + (px < 0 ? xres : px >= xres ? -xres : 0); |
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copycolor(pval, scan[px]); |
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pc = x_c*(px+.5); |
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pr = y_r*(py+.5); |
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ksiz = CHECKRAD*m*rad + 1; |
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if (ksiz > orad) ksiz = orad; |
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/* compute normalization */ |
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norm = 0.0; |
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i = 0; |
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for (r = rcent-ksiz; r <= rcent+ksiz; r++) { |
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if (r < 0) continue; |
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if (r >= nrows) break; |
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dy2 = (pr - (r+.5))/(m*rad); |
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dy2 *= dy2; |
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for (c = ccent-ksiz; c <= ccent+ksiz; c++) { |
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if (!wrapfilt) { |
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if (c < 0) continue; |
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if (c >= ncols) break; |
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} |
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dx = (pc - (c+.5))/(m*rad); |
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norm += warr[i++] = lookgauss(dx*dx + dy2); |
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} |
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} |
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norm = 1.0/norm; |
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if (x_c < 1.0) norm *= x_c; |
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if (y_r < 1.0) norm *= y_r; |
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/* sum pixels */ |
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i = 0; |
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for (r = rcent-ksiz; r <= rcent+ksiz; r++) { |
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if (r < 0) continue; |
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if (r >= nrows) break; |
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scan = scoutbar[r%obarsize]; |
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for (c = ccent-ksiz; c <= ccent+ksiz; c++) { |
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offs = c < 0 ? ncols : c >= ncols ? -ncols : 0; |
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if (offs && !wrapfilt) |
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continue; |
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copycolor(ctmp, pval); |
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dx = norm*warr[i++]; |
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scalecolor(ctmp, dx); |
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addcolor(scan[c+offs], ctmp); |
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} |
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} |
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} |
