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static char *rcs_id = "$Id: fixup_fujitsu_grayscale.c,v 1.1 1997/03/11 03:23:11 kstailey Exp $";
/*
* Copyright (c) 1995 Kenneth Stailey
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed for the NetBSD Project
* by Kenneth Stailey
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* fixup_fujitsu_grayscale.c: convert scanner output to PGM
*
* This is faster than using "pgminvert | pnmgamma" but does the same
* thing basically.
*/
#include <stdio.h>
#include <math.h>
static int gamma_table[256];
void buildgamma(double gamma)
{
int i, v;
double one_over_gamma, index;
one_over_gamma = 1.0 / gamma;
for (i = 0; i <= 255; ++i) {
index = (double)i / 255.0;
v = (255.0 * pow(index, one_over_gamma)) + 0.5;
if (v > 255)
v = 255;
gamma_table[i] = 255 - v;
}
}
main()
{
int ch;
buildgamma(0.75);
while ((ch = getchar()) != EOF)
putchar((char)(gamma_table[ch]));
}
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