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/* pgmkernel.c - generate a portable graymap convolution kernel
**
** Creates a Portable Graymap file containing a convolution filter
** with max value = 255 and minimum value > 127 that can be used as a
** smoothing kernel for pnmconvol.
**
** Copyright (C) 1992 by Alberto Accomazzi, Smithsonian Astrophysical
** Observatory.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
#include <math.h>
#include "pgm.h"
#include "mallocvar.h"
int
main ( argc, argv )
int argc;
char *argv[];
{
register int i, j;
int argn = 1, ixsize, iysize, maxval = 255;
double fxsize = 0.0, fysize = 0.0, w = 6.0, kxcenter, kycenter,
tmax = 0, *fkernel;
const char *usage = "[-weight f] width [height]";
pgm_init( &argc, argv );
while ( argn < argc && argv[argn][0] == '-' && argv[argn][1] != '\0' )
{
if ( pm_keymatch( argv[argn], "-weight", 2 )) {
if (++argn >= argc)
pm_usage( usage );
else if (sscanf(argv[argn], "%lf", &w) != 1)
pm_usage( usage );
}
else
pm_usage( usage );
argn++;
}
if (argn == argc)
pm_usage( usage );
if (sscanf(argv[argn], "%lf", &fxsize) != 1)
pm_error( "error reading input kernel x size, (%s)\n", argv[argn]);
++argn;
if (argn == argc - 1) {
if (sscanf(argv[argn], "%lf", &fysize) != 1)
pm_error( "error reading input kernel y size, (%s)\n", argv[argn]);
}
else if (argn == argc)
fysize = fxsize;
else
pm_usage( usage );
if (fxsize <= 1 || fysize <= 1)
pm_usage( usage );
kxcenter = (fxsize - 1) / 2.0;
kycenter = (fysize - 1) / 2.0;
ixsize = fxsize + 0.999;
iysize = fysize + 0.999;
MALLOCARRAY(fkernel, ixsize * iysize);
for (i = 0; i < iysize; i++)
for (j = 0; j < ixsize; j++) {
fkernel[i*ixsize+j] = 1.0 / (1.0 + w * sqrt((double)
(i-kycenter)*(i-kycenter)+
(j-kxcenter)*(j-kxcenter)));
if (tmax < fkernel[i*ixsize+j])
tmax = fkernel[i*ixsize+j];
}
/* output PGM header + data (ASCII format only) */
printf("P2\n%d %d\n%d\n", ixsize, iysize, maxval);
for (i = 0; i < iysize; i++, printf("\n"))
for (j = 0; j < ixsize; j++)
printf(" %3d", (int)(maxval * (fkernel[i*ixsize+j] /
(2*tmax) + 0.5)));
exit(0);
}
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