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/* ppmrelief.c - generate a relief map of a portable pixmap
**
** Copyright (C) 1990 by Wilson H. Bent, Jr.
**
** 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 <stdio.h>
#include "pm_c_util.h"
#include "ppm.h"
int
main(int argc, char * argv[]) {
FILE* ifp;
pixel** inputbuf;
pixel* outputrow;
int argn, rows, cols, format, row;
register int col;
pixval maxval, mv2;
const char* const usage = "[ppmfile]";
ppm_init( &argc, argv );
argn = 1;
if ( argn != argc ) {
ifp = pm_openr( argv[argn] );
++argn;
} else
ifp = stdin;
if ( argn != argc )
pm_usage( usage );
ppm_readppminit( ifp, &cols, &rows, &maxval, &format );
if (cols < 3 || rows < 3 )
pm_error("Input image too small: %u x %u. Must be at least 3x3",
cols, rows);
mv2 = maxval / 2;
/* Allocate space for 3 input rows, plus an output row. */
inputbuf = ppm_allocarray( cols, 3 );
outputrow = ppm_allocrow( cols );
ppm_writeppminit( stdout, cols, rows, maxval, 0 );
/* Read in the first two rows. */
ppm_readppmrow( ifp, inputbuf[0], cols, maxval, format );
ppm_readppmrow( ifp, inputbuf[1], cols, maxval, format );
/* Write out the first row, all zeros. */
for ( col = 0; col < cols; ++col )
PPM_ASSIGN( outputrow[col], 0, 0, 0 );
ppm_writeppmrow( stdout, outputrow, cols, maxval, 0 );
/* Now the rest of the image - read in the 3rd row of inputbuf,
** and convolve with the first row into the output buffer.
*/
for ( row = 2 ; row < rows; ++row ) {
pixval r, g, b;
int rowa, rowb;
rowa = row % 3;
rowb = (row + 2) % 3;
ppm_readppmrow( ifp, inputbuf[rowa], cols, maxval, format );
for ( col = 0; col < cols - 2; ++col ) {
r = MAX(0, MIN(maxval, PPM_GETR( inputbuf[rowa][col] ) +
( mv2 - PPM_GETR( inputbuf[rowb][col + 2] ) )));
g = MAX(0, MIN(maxval, PPM_GETG( inputbuf[rowa][col] ) +
( mv2 - PPM_GETG( inputbuf[rowb][col + 2] ) )));
b = MAX(0, MIN(maxval, PPM_GETB( inputbuf[rowa][col] ) +
( mv2 - PPM_GETB( inputbuf[rowb][col + 2] ) )));
PPM_ASSIGN( outputrow[col + 1], r, g, b );
}
ppm_writeppmrow( stdout, outputrow, cols, maxval, 0 );
}
/* And write the last row, zeros again. */
for ( col = 0; col < cols; ++col )
PPM_ASSIGN( outputrow[col], 0, 0, 0 );
ppm_writeppmrow( stdout, outputrow, cols, maxval, 0 );
pm_close( ifp );
pm_close( stdout );
exit( 0 );
}
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