/* ----------------------------------------
Image Processing pg1.c
Image Ratio Processing / NDVI Gray Image Output
(c)Ichinoseki National College Advanced Course
------------------------------------------ */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>  

main(argc,argv)
int argc;
char *argv[]; 
{
	static int  i,j,m;
	static double a1,a2,a3;
	static int pixel,line;
	FILE *fp1,*fp2,*fp3; 

	/* Command parameter check  */
	if (argc!=6){
		printf("Usage : command input_file1 input_file2 pixel line output_file\n");
		return 1;
	}
	/* Image size parameter load */
	sscanf(argv[3],"%d",&pixel);
	sscanf(argv[4],"%d",&line);
	
	/* Input image file1 check */
	if (( fp1=fopen(argv[1],"r") )==NULL){
		printf("Can't open input_file\n");
		return 1;
	}
	/* Input image file1 check */
	if (( fp2=fopen(argv[2],"r") )==NULL){
		printf("Can't open input_file\n");
		return 1;
	}

	/* Output image file check */
	if (( fp3=fopen(argv[5],"w") )==NULL){
		printf("Can't open output_file\n");
		return 1;
	}

	/* Skip header data of Input Image */
	fseek(fp1,24,0);
	fseek(fp2,24,0);

	/* ppm header output */
	fprintf(fp3,"P5\n");
	fprintf(fp3,"# INCT\n");
	fprintf(fp3,"%s %s\n",argv[3],argv[4]);
	fprintf(fp3,"255\n");

	/* NDVI processing */
	for (j=0; j<line; j++)
	{
	for (i=0; i<pixel; i++)
	{
		a1=(double)getc(fp1);
		a2=(double)getc(fp2);
		a3=(a1-a2)/(a1+a2);
		m=(1+a3)*128;
		putc(m,fp3);
	}
	}

	fclose(fp1);
	fclose(fp2);
	fclose(fp3);
	return 0;
}