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Photo CD Demo 1
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fbm
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src
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fbgamma.c
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C/C++ Source or Header
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1990-06-24
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162 lines
/*****************************************************************
* fbgamma.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.
*
* fbgamma.c: Apply a gamma transform to a colormapped image
*
* USAGE
* % fbgamma [ -<type> ] [ amount ] < image1 > image2
*
* EDITLOG
* LastEditDate = Mon Jun 25 00:02:30 1990 - Michael Mauldin
* LastFileName = /usr2/mlm/src/misc/fbm/fbgamma.c
*
* HISTORY
* 25-Jun-90 Michael Mauldin (mlm@cs.cmu.edu) Carnegie Mellon
* Package for Release 1.0
*
* 05-Apr-89 Michael Mauldin (mlm) at Carnegie-Mellon University
* Created.
*****************************************************************/
# include <stdio.h>
# include <math.h>
# include "fbm.h"
# define USAGE \
"Usage: fbgamma [ -<type> ] [ amount ] < image > image"
#ifndef lint
static char *fbmid =
"$FBM fbgamma.c <1.0> 25-Jun-90 (C) 1989,1990 by Michael Mauldin, source \
code available free from MLM@CS.CMU.EDU and from UUNET archives$";
#endif
int debug = 0;
double expon = 1.0;
main (argc, argv)
char *argv[];
{ FBM image;
int outtype = DEF_8BIT;
double amount = 2.2, atof ();
char *fname = NULL;
/* Get the options */
while (--argc > 0 && (*++argv)[0] == '-')
{ while (*++(*argv))
{ switch (**argv)
{
case 'd': debug++; break;
case 'A': outtype = FMT_ATK; break;
case 'B': outtype = FMT_FACE; break;
case 'F': outtype = FMT_FBM; break;
case 'G': outtype = FMT_GIF; break;
case 'I': outtype = FMT_IFF; break;
case 'L': outtype = FMT_LEAF; break;
case 'M': outtype = FMT_MCP; break;
case 'P': outtype = FMT_PBM; break;
case 'R': outtype = FMT_RLE; break;
case 'S': outtype = FMT_SUN; break;
case 'T': outtype = FMT_TIFF; break;
case 'X': outtype = FMT_X11; break;
case 'Z': outtype = FMT_PCX; break;
default: fprintf (stderr, "%s\n", USAGE);
exit (1);
}
}
}
if (argc > 0)
{ amount = atof (argv[0]); }
if (argc > 1)
{ fname = argv[1]; }
/* Clear the memory pointers so alloc_fbm won't be confused */
image.cm = image.bm = (unsigned char *) NULL;
/* Read the image */
if (read_bitmap (&image, fname))
{ int h, w, k;
/* Determine output height & width (oh*ow <= size) */
h = image.hdr.rows;
w = image.hdr.cols;
k = image.hdr.planes;
fprintf (stderr,
"Gamma correct \"%s\", gamma %1.3lf [%dx%dx%d]\n",
image.hdr.title[0] ? image.hdr.title : "(untitled)",
amount, w, h, k);
if (gamma_fbm (&image, amount) &&
write_bitmap (&image, stdout, outtype))
{ exit (0); }
}
exit (1);
}
gamma_fbm (image, amount)
FBM *image;
double amount;
{ double clr;
register int i, w, h, k;
register unsigned char *bmp, *btail;
int cmap[256];
/* Determine output height & width (oh*ow <= size) */
h = image->hdr.rows;
w = image->hdr.cols;
k = image->hdr.planes;
expon = 1.0 / amount;
if (image->hdr.clrlen > 0)
{
for (i=0; i<image->hdr.clrlen; i++)
{
if (debug) fprintf (stderr, "value %3d => ", image->cm[i]);
image->cm[i] = gamma_clr (image->cm[i]);
if (debug) fprintf (stderr, "%3d\n", image->cm[i]);
}
}
else
{
for (i=0; i<255; i++)
{ cmap[i] = gamma_clr (i);
if (debug) fprintf (stderr, "value %3d => %3d\n", i, cmap[i]);
}
bmp = image->bm;
btail = bmp + image->hdr.plnlen * image->hdr.planes;
while (bmp < btail)
{ *bmp++ = cmap[*bmp]; }
}
return (1);
}
int gamma_clr (value)
int value;
{ double clr, floor ();
int newclr;
/* First compute new color */
clr = 255.0 * pow ((value / 255.0), expon);
/* Round to nearest integer */
newclr = (int) floor (clr + 0.5);
return (newclr);
}