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/* ppmtopgm.c - convert a portable pixmap to a portable graymap
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** 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 "pm_c_util.h"
#include "ppm.h"
#include "pgm.h"
#include "lum.h"
static void
convertRaster(FILE * const ifP,
unsigned int const cols,
unsigned int const rows,
pixval const maxval,
int const format,
pixel * const inputRow,
gray * const outputRow,
FILE * const ofP) {
unsigned int row;
for (row = 0; row < rows; ++row) {
ppm_readppmrow( ifP, inputRow, cols, maxval, format );
if (maxval <= 255) {
/* Use fast approximation to 0.299 r + 0.587 g + 0.114 b */
unsigned int col;
for (col = 0; col < cols; ++col)
outputRow[col] = (gray) ppm_fastlumin(inputRow[col]);
} else {
/* Can't use fast approximation, so fall back on floats. */
unsigned int col;
for (col = 0; col < cols; ++col)
outputRow[col] = ppm_luminosity(inputRow[col]);
}
pgm_writepgmrow(ofP, outputRow, cols, maxval, 0);
}
}
int
main(int argc, char *argv[]) {
FILE* ifP;
const char * inputFilespec;
int eof;
ppm_init( &argc, argv );
if (argc-1 > 1)
pm_error("The only argument is the (optional) input filename");
if (argc == 2)
inputFilespec = argv[1];
else
inputFilespec = "-";
ifP = pm_openr(inputFilespec);
eof = FALSE; /* initial assumption */
while (!eof) {
ppm_nextimage(ifP, &eof);
if (!eof) {
int rows, cols, format;
pixval maxval;
pixel* inputRow;
gray* outputRow;
ppm_readppminit(ifP, &cols, &rows, &maxval, &format);
pgm_writepgminit(stdout, cols, rows, maxval, 0);
inputRow = ppm_allocrow(cols);
outputRow = pgm_allocrow(cols);
convertRaster(ifP, cols, rows, maxval, format,
inputRow, outputRow, stdout);
ppm_freerow(inputRow);
pgm_freerow(outputRow);
}
}
pm_close(ifP);
pm_close(stdout);
return 0;
}
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