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Photo CD Demo 1
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flthre.c
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C/C++ Source or Header
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1990-06-24
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90 lines
/*****************************************************************
* flthre.c: FBM Release 1.0 25-Feb-90 Michael Mauldin
*
* Copyright (C) 1989,1990 by Michael Mauldin. Permission is granted
* to use this file in whole or in part for any purpose, educational,
* recreational or commercial, provided that this copyright notice
* is retained unchanged. This software is available to all free of
* charge by anonymous FTP and in the UUNET archives.
*
* flthre.c:
*
* CONTENTS:
* thesh_fbm (input, output, thresh)
*
* EDITLOG
* LastEditDate = Mon Jun 25 00:18:08 1990 - Michael Mauldin
* LastFileName = /usr2/mlm/src/misc/fbm/flthre.c
*
* HISTORY
* 25-Jun-90 Michael Mauldin (mlm@cs.cmu.edu) Carnegie Mellon
* Package for Release 1.0
*
* 16-Jun-89 Michael Mauldin (mlm) at Carnegie Mellon University
* Bug fix from Dave Cohrs <dave@cs.wisc.edu>
*
* 07-Mar-89 Michael Mauldin (mlm) at Carnegie Mellon University
* Beta release (version 0.9) mlm@cs.cmu.edu
*
* 10-Dec-88 Michael Mauldin (mlm) at Carnegie-Mellon University
* Created.
*****************************************************************/
# include <stdio.h>
# include <math.h>
# include <ctype.h>
# include "fbm.h"
/*****************************************************************
* thesh_fbm: Threshhold halftoning
*****************************************************************/
# define RAND(RN) (((seed = 1103515245 * seed + 12345) >> 12) % (RN))
#ifndef lint
static char *fbmid =
"$FBM flthre.c <1.0> 25-Jun-90 (C) 1989,1990 by Michael Mauldin, source \
code available free from MLM@CS.CMU.EDU and from UUNET archives$";
#endif
thesh_fbm (input, output, thresh)
FBM *input, *output;
register int thresh;
{ register unsigned char *bmp, *obm;
register int i, j, rowlen, w, h, outrow;
if (input->hdr.planes != 1)
{ fprintf (stderr, "thesh_fbm: can't halftone color images\n");
return (0);
}
fprintf (stderr, "Threshhold halftoning, thesh %d\n", thresh);
/* Allocate output */
free_fbm (output);
output->hdr = input->hdr;
output->hdr.bits = 1;
output->hdr.physbits = 8;
outrow = 16 * ((input->hdr.cols + 15) / 16); /* Pad to even byte boundary */
output->hdr.rowlen = outrow;
output->hdr.plnlen = outrow*output->hdr.rows;
alloc_fbm (output);
w = input->hdr.cols;
h = input->hdr.rows;
rowlen = input->hdr.rowlen;
/* Now do threshholding */
for (j=0; j<h; j++)
{ /* scan left to right */
bmp = &input->bm[j*rowlen];
obm = &output->bm[j*outrow];
for (i=1; i<w; i++)
{ obm[i] = bmp[i] > thresh ? WHITE : BLACK; }
}
return (1);
}