seperate

/********************************************************************/
/*Seperate SGI color image to BW image files                                                                 */
/*File name: seperate.c                                                                                                    */
/*Author:    Yurong Sun                                                                                                   */
/*Description:                                                                                                                  */
/*            Read color SGI format image file                                                                      */
/*            Create three grayscale BW format images relative to r, g, b channels                  */
/********************************************************************/
#include "stdio.h"

putbyte(outf,val)
FILE *outf;
unsigned char val;
{
    unsigned char buf[1];

    buf[0] = val;
    fwrite(buf,1,1,outf);
}

putshort(outf,val)
FILE *outf;
unsigned short val;
{
    unsigned char buf[2];

    buf[0] = (val>>8);
    buf[1] = (val>>0);
    fwrite(buf,2,1,outf);
}

static int putlong(outf,val)
FILE *outf;
unsigned long val;
{
    unsigned char buf[4];

    buf[0] = (val>>24);
    buf[1] = (val>>16);
    buf[2] = (val>>8);
    buf[3] = (val>>0);
    return fwrite(buf,4,1,outf);
}

unsigned short getshort()
{
unsigned char buf[2];
fread(buf, 2, 1, inf);
return (buf[0]<<8) + (buf[1]<<0);
}

static long getlong()
{
unsigned char buf[4];
fread(buf, 4, 1, inf);
return (buf[0]<<24) + (buf[1]<<16)+ (buf[2]<<8) + (buf[3]<<0);
}

#define IXSIZE (800)
#define IYSIZE (800)
#define IZZIZE (3)

main(argc, argv)
int   argc;
char **argv;
{
    FILE *of, *inf;
    char iname[80];
unsigned char inbuf[IXSIZE][IYSIZE][IZSIZE];
    int i, x, y,z;
unsigned short magic, dimension, ixsi, iysi, izsi, ixsi1, iysi1;
static long colormap, pixmin, pixmax;
char storage, bpc;

/* make sure the user invokes this program properly */
if(argc != 5) {
fprintf(stderr, "Usage: seperate in.rgb outr.bw outg.bw outb.bw\n");
exit(1);
}

/* Read the input RGB file*/
if ((inf=fopen(argv[1], "r"))==NULL)
{
fprintf(stderr, "readImage: Can't open file %s\n", argv[1]);
exit(1);
}
else
{
magic = getshort(); /* 2 bytes short magic */
storage = fgetc(inf); /* 1 byte char storage */
bpc = fgetc(inf); /* 1 byte char bpc */
dimension = getshort();/* 2 bytes short dimension */

ixsi = getshort(); /* 2 bytes xsize */
iysi = getshort(); /* 2 bytes ysize */
izsi = getshort(); /* 2 bytes zsize */

pixmin = getlong(); /* 4 bytes pixel minimum */
pixmax = getlong(); /* 4 bytes pixel maximum */

for (i = 0; i < 84; i++)
fgetc(inf); /* 4 bytes char dummy and 80 bytes char imagename */

colormap = getlong();

for (i = 0; i < 404; i++)
fgetc(inf); /* 404 byters char dummy */

for (z=0; z < izsi; z++)
   for (y=0; y < iysi; y++)
    for (x=0; x < ixsi; x++)
     fread(&inbuf[x][y][z], 1, 1, inf);
}
fclose(inf);

/*Begin to write output files */
ixsi1=0;
iysi1=0;
/* output the red channel BW file */
    of = fopen(argv[2],"w");
    if(!of) {
        fprintf(stderr,"sgiimage: can't open output file\n");
        exit(1);
    }
putshort(of, ixsi1);
putshort(of, ixsi);
putshort(of, iysi1);
putshort(of, iysi);

for (y=0; y < iysi; y++)
for (x=0; x < ixsi; x++)
fwrite(&inbuf[x][y][0], 1, 1, of);

fclose(of);

/* output the green channel BW file */
    of = fopen(argv[3],"w");
    if(!of) {
        fprintf(stderr,"sgiimage: can't open output file\n");
        exit(1);
    }
putshort(of, ixsi1);
putshort(of, ixsi);
putshort(of, iysi1);
putshort(of, iysi);

for (y=0; y < iysi; y++)
for (x=0; x < ixsi; x++)
fwrite(&inbuf[x][y][1], 1, 1, of);

fclose(of);

/* output the blue channel BW file */
    of = fopen(argv[4],"w");
    if(!of) {
        fprintf(stderr,"sgiimage: can't open output file\n");
        exit(1);
    }
putshort(of, ixsi1);
putshort(of, ixsi);
putshort(of, iysi1);
putshort(of, iysi);

for (y=0; y < iysi; y++)
for (x=0; x < ixsi; x++)
fwrite(&inbuf[x][y][2], 1, 1, of);

fclose(of);
}