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/* pbmtopgm.c - convert PBM to PGM by totalling pixels over sample area
* AJCD 12/12/90
*/
#include <stdio.h>
#include <limits.h>
#include "pm_c_util.h"
#include "pgm.h"
int
main(int argc, char *argv[]) {
gray *outrow, maxval;
int right, left, down, up;
bit **inbits;
int rows, cols;
FILE *ifd;
int row;
int width, height;
const char * const usage = "<w> <h> [pbmfile]";
pgm_init( &argc, argv );
if (argc > 4 || argc < 3)
pm_usage(usage);
width = atoi(argv[1]);
height = atoi(argv[2]);
if (width < 1 || height < 1)
pm_error("width and height must be > 0");
if (width > INT_MAX / height)
/* prevent overflow of "value" below */
pm_error("sample area (%u columns %u rows) too large",
width, height);
left=width/2; right=width-left;
up=height/2; down=height-up;
if (argc == 4)
ifd = pm_openr(argv[3]);
else
ifd = stdin ;
inbits = pbm_readpbm(ifd, &cols, &rows) ;
if (width > cols)
pm_error("You specified a sample width (%u columns) which is greater "
"than the image width (%u columns)", height, rows);
if (height > rows)
pm_error("You specified a sample height (%u rows) which is greater "
"than the image height (%u rows)", height, rows);
outrow = pgm_allocrow(cols) ;
maxval = MIN(PGM_OVERALLMAXVAL, width*height);
pgm_writepgminit(stdout, cols, rows, maxval, 0) ;
for (row = 0; row < rows; row++) {
int const t = (row > up) ? (row-up) : 0;
int const b = (row+down < rows) ? (row+down) : rows;
int const onv = height - (t-row+up) - (row+down-b);
unsigned int col;
for (col = 0; col < cols; col++) {
int const l = (col > left) ? (col-left) : 0;
int const r = (col+right < cols) ? (col+right) : cols;
int const onh = width - (l-col+left) - (col+right-r);
int value;
int x;
value = 0; /* initial value */
for (x = l; x < r; ++x) {
int y;
for (y = t; y < b; ++y)
if (inbits[y][x] == PBM_WHITE)
++value;
}
outrow[col] = maxval*value/(onh*onv);
}
pgm_writepgmrow(stdout, outrow, cols, maxval, 0) ;
}
pm_close(ifd);
return 0;
}
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