/*----------------------------------------------------------------------------
   
   File name    :   3color.c
   Author       :	Nicolas Devillard
   Created on   :	Dec 13, 1997
   Description  :	3 color image combination

 ---------------------------------------------------------------------------*/

/*
	$Id: 3color.c,v 1.15 2002/01/29 12:35:52 ndevilla Exp $
	$Author: ndevilla $
	$Date: 2002/01/29 12:35:52 $
	$Revision: 1.15 $
 */

/*----------------------------------------------------------------------------
                                Includes
 ---------------------------------------------------------------------------*/

#include <stdio.h>
#include <string.h>

#include "eclipse.h"

/* This function just gives the usage for the program   */
static void
usage(char *pname) ;

static char prog_desc[] = "3 color combination" ;
 
/*----------------------------------------------------------------------------
                            Main code
 ---------------------------------------------------------------------------*/

int main(int argc, char *argv[])
{
    char        	inn[3][FILENAMESZ+1],
                	outname[FILENAMESZ+1] ;
	image_t		*	im[3] ;
	FILE		*	outppm ;
	int				i,j ;
	int				pos_in,
					pos_out ;
	pixelvalue		minpix[3],
					maxpix[3] ;
	double			A[3],
					B[3] ;
	unsigned char*	buf ;

    if (argc<5)
        usage(argv[0]) ;

	/* Initialize eclipse environment */
	eclipse_init();

    /* Get arguments    */
	strncpy(inn[0], argv[1], FILENAMESZ) ;
	strncpy(inn[1], argv[2], FILENAMESZ) ;
	strncpy(inn[2], argv[3], FILENAMESZ) ;
	strncpy(outname, argv[4], FILENAMESZ) ;

	/* load all images */
	for (i=0 ; i<3 ; i++) {
		im[i] = image_load(inn[i]) ;
		if (im[i]==NULL) {
			e_error("cannot load image [%s]", inn[i]);
			return -1 ;
		}
	}

	if ((im[0]->lx != im[1]->lx) ||
		(im[0]->lx != im[2]->lx) ||
		(im[0]->ly != im[1]->ly) ||
		(im[0]->ly != im[2]->ly)) {
		e_error("input images have incompatible sizes\n"
				"red   is [%d %d]\n"
				"green is [%d %d]\n"
				"blue  is [%d %d]",
				im[0]->lx, im[0]->ly,
				im[1]->lx, im[1]->ly,
				im[2]->lx, im[2]->ly) ;
		image_del(im[0]) ;
		image_del(im[1]) ;
		image_del(im[2]) ;
		return -1 ;
	}

	printf("*** channels\n") ;
	printf("red               : %s\n", inn[0]) ;
	printf("green             : %s\n", inn[1]) ;
	printf("blue              : %s\n", inn[2]) ;
	printf("\n") ;
	printf("24 bit PPM output : %s\n", outname) ;

	/* find minimum and maximum pixel values for the 3 images */

	maxpix[0] = minpix[0] = im[0]->data[0] ;
	maxpix[1] = minpix[1] = im[1]->data[0] ;
	maxpix[2] = minpix[2] = im[2]->data[0] ;

	for (i=0 ; i<(im[0]->lx * im[0]->ly) ; i++) {
		for (j=0 ; j<3 ; j++) {
			if (im[j]->data[i] < minpix[j])
				minpix[j] = im[j]->data[i] ;
			if (im[j]->data[i] > maxpix[j])
				maxpix[j] = im[j]->data[i] ;
		}
	}

	for (i=0 ; i<3 ; i++) {
		A[i] = 255.0 / (maxpix[i] - minpix[i]) ;
		B[i] = - A[i] * minpix[i] ;
	}

	
	outppm = fopen(outname, "w") ;
	if (outppm == NULL) {
		e_error("cannot open file [%s] for output: aborting", outname);
		image_del(im[0]) ;
		image_del(im[1]) ;
		image_del(im[2]) ;
	}

	/* output an image in PPM P6 format */

	/* header information */
	fprintf(outppm, "P6\n") ;
	fprintf(outppm, "%d %d\n", im[0]->lx, im[0]->ly) ;
	fprintf(outppm, "255\n") ;

	/* allocate output buffer */
	buf = (unsigned char *)malloc(3 * im[0]->lx * im[0]->ly) ;

	/* pixel values */
	for (j=im[0]->ly-1 ; j>=0 ; j--) {
		for (i=0 ; i<im[0]->lx ; i++) {
			pos_in = i+j*im[0]->lx ;
			pos_out = i+(im[0]->ly-1-j)*im[0]->lx ;

			buf[3*pos_out]=
				(unsigned char)(0.5+A[0]*(double)im[0]->data[pos_in]+B[0]); 
			buf[3*pos_out+1]=
				(unsigned char)(0.5+A[1]*(double)im[1]->data[pos_in]+B[1]); 
			buf[3*pos_out+2]=
				(unsigned char)(0.5+A[2]*(double)im[2]->data[pos_in]+B[2]); 
		}
	}

	fwrite(buf, 3 * im[0]->lx * im[0]->ly, 1, outppm) ;
	free(buf) ;
	fclose(outppm) ;

	image_del(im[0]) ;
	image_del(im[1]) ;
	image_del(im[2]) ;

	if (debug_active())
		xmemory_status();

    return 0 ;
}

/*
 * This function only gives the usage for the program
 */

static void
usage(char *pname)
{
	hello_world(pname, prog_desc) ;
	printf("\nuse: %s <red> <green> <blue> <out>\n", pname) ;
    printf("\n") ;
    exit(0) ;
}