pixtoppm - convert BRL .pix images to ppm

[Steve Hayman]

Some RGB images of the Iraq war are available from ftp.brl.mil.
See "comp.graphics" for details.

They're in "BRL-CAD .pix" format - here is a tool that will
convert those images to the PPM Portable Pixmap format (part of
the PBM toolkit) , so you can view them with
tools such as 'xv'.

This is a quick hack that I wrote in about 10 minutes
so it has no options and no guarantee.  But this is "alt.sources".

sample use:
    get the images
    zcat map-scud-targets.Z | ./pixtoppm >map-scud-targets.ppm
    xv map-scud-targets.ppm

#include <stdio.h>

/*
 * convert BRL .pix files to ppm
 * zcat file.Z | pixtoppm >
 * sahayman at iuvax.cs.indiana.edu 1991 01 18
 *
 * brl says this about the format:
 *
 * These compressed images are in BRL-CAD .pix file format.
 * They are 24-bits/pixel, 720 by 486 pixels.
 *
 * Pixels run left-to-right, from the bottom of the screen to the top.
 *
 *	Mike @ BRL.MIL
 */

#define WIDTH 720
#define HEIGHT 486
#define BYTESPERPIXEL 3

#define SIZE (WIDTH * HEIGHT * BYTESPERPIXEL)


char *map;
char *malloc();

main()
{

    char buf[512];
    int i;
    char *row;
    /*
     * magic number
     */

    printf("P6\n");

    /*
     * width height
     */
    printf("%d %d\n", WIDTH, HEIGHT);

    /*
     * maximum color component value
     */

    printf("255\n");
    fflush(stdout);

    /*
     * now gobble up the bytes
     */

    map = malloc( SIZE );
    if ( map == NULL ) {
	perror("malloc");
	exit(1);
    }


    if ( fread(map, 1, SIZE, stdin) == 0 ) {
	fprintf(stderr, "Short read\n");
	exit(1);
    }

    /*
     * now write out the rows in the right order, 'cause the
     * input is upside down.
     */
    
    for ( i = 0; i < HEIGHT; i++ ) {
	row = map + (HEIGHT - i) * WIDTH * 3;

	fwrite(row, 1, WIDTH*3, stdout);
    }

    exit(0);
}