Club Amiga de Montreal - CAM/CAM_CD_1.iso/files/309.lha/PBM_PLUS/pgm/pgmnorm.c

C/C++ Source or Header | 1980-12-04 | 5KB | 171 lines

/* pgmnorm.c - read a portable graymap and normalize the contrast
**
** 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 <stdio.h>
#ifdef    SYSV
#include <string.h>
#else    SYSV
#include <strings.h>
#endif    SYSV
#include "pgm.h"

#define max(a,b) ((a) > (b) ? (a) : (b))
#define MAXMAXVAL 1023

main( argc, argv )
int argc;
char *argv[];
    {
    FILE *ifd;
    gray maxval, **grays;
    register gray range, *gP;
    int argn, rows, cols, row, hist[MAXMAXVAL+1], i, size, cutoff, count;
    float bpercent, wpercent;
    int bvalue, wvalue;
    int specbpercent, specbvalue, specwpercent, specwvalue;
    register int col;
    char *usage = "[-bpercent <n> | -bvalue <n>] [-wpercent <n> | -wvalue <n>] [pgmfile]";

    pm_progname = argv[0];

    argn = 1;
    bpercent = 2.0;
    wpercent = 1.0;
    specbpercent = specbvalue = specwpercent = specwvalue = 0;

    while ( argn + 1 < argc && argv[argn][0] == '-' )
    {
    if ( strncmp(argv[argn],"-bpercent",max(strlen(argv[argn]),3)) == 0 )
        {
        if ( specbvalue )
        pm_error(
            "only one of -bpercent and -bvalue may be specified",
            0,0,0,0,0 );
        if ( sscanf( argv[argn+1], "%g", &bpercent ) != 1 )
        pm_usage( usage );
        if ( bpercent < 0.0  || bpercent > 100.0 )
        pm_error(
            "black percentage must between 0 and 100", 0,0,0,0,0 );
        specbpercent = 1;
        }
    else if ( strncmp(argv[argn],"-bvalue",max(strlen(argv[argn]),3)) == 0 )
        {
        if ( specbpercent )
        pm_error(
            "only one of -bpercent and -bvalue may be specified",
            0,0,0,0,0 );
        if ( sscanf( argv[argn+1], "%d", &bvalue ) != 1 )
        pm_usage( usage );
        if ( bvalue < 0 )
        pm_error( "black value must be >= 0", 0,0,0,0,0 );
        specbvalue = 1;
        }
    else if ( strncmp(argv[argn],"-wpercent",max(strlen(argv[argn]),3)) == 0 )
        {
        if ( specwvalue )
        pm_error(
            "only one of -wpercent and -wvalue may be specified",
            0,0,0,0,0 );
        if ( sscanf( argv[argn+1], "%g", &wpercent ) != 1 )
        pm_usage( usage );
        if ( wpercent < 0.0 || wpercent > 100.0 )
        pm_error(
            "white percentage must be between 0 and 100", 0,0,0,0,0 );
        specwpercent = 1;
        }
    else if ( strncmp(argv[argn],"-wvalue",max(strlen(argv[argn]),3)) == 0 )
        {
        if ( specwpercent )
        pm_error(
            "only one of -wpercent and -wvalue may be specified",
            0,0,0,0,0 );
        if ( sscanf( argv[argn+1], "%d", &wvalue ) != 1 )
        pm_usage( usage );
        if ( wvalue < 0 )
        pm_error( "white value must be >= 0", 0,0,0,0,0 );
        specwvalue = 1;
        }
    else
        pm_usage( usage );
    argn += 2;
    }

    if ( argn < argc )
    {
    ifd = pm_openr( argv[argn] );
    argn++;
    }
    else
    ifd = stdin;

    if ( argn != argc )
    pm_usage( usage );

    grays = pgm_readpgm( ifd, &cols, &rows, &maxval );

    pm_close( ifd );

    if ( ( ! specbvalue ) || ( ! specwvalue ) )
    {
    /* Build histogram. */
    for ( i = 0; i <= maxval; i++ )
        hist[i] = 0;
    for ( row = 0; row < rows; row++ )
        for ( col = 0, gP = grays[row]; col < cols; col++, gP++ )
        hist[*gP]++;
    size = rows * cols;
    if ( ! specbvalue )
        { /* Compute bvalue from bpercent. */
        cutoff = size * bpercent / 100.0;
        count = 0;
        for ( bvalue = 0; bvalue <= maxval; bvalue++ )
        {
        count += hist[bvalue];
        if ( count > cutoff )
        break;
        }
        }
    if ( ! specwvalue )
        { /* Compute wvalue from wpercent. */
        cutoff = size * wpercent / 100.0;
        count = 0;
        for ( wvalue = maxval; wvalue >= 0; wvalue-- )
        {
        count += hist[wvalue];
        if ( count > cutoff )
            break;
        }
        }
    }

    /* Now rescale so that bvalue maps to 0, wvalue maps to maxval. */
    fprintf(
    stderr, "(Remapping %d..%d to %d..%d.)\n", bvalue, wvalue, 0, maxval );
    pgm_writepgminit( stdout, cols, rows, maxval );
    range = wvalue - bvalue;
    for ( row = 0; row < rows; row++ )
    {
        for ( col = 0, gP = grays[row]; col < cols; col++, gP++ )
        {
        if ( *gP <= bvalue )
        *gP = 0;
        else if ( *gP >= wvalue )
        *gP = maxval;
        else
        *gP = ( *gP - bvalue ) * maxval / range;
        }
    pgm_writepgmrow( stdout, grays[row], cols, maxval );
    }

    exit( 0 );
    }