/* 
  chenge 16bit (0-1000 [%x10]) to 8bit [0-255]
  for generation RGB composite image (visible version).  
  used compiler: gcc 
  made by: Atsushi Higuchi, CEReS, Chiba Univ. Japan

Version history:
ver.0.1 27 dec 2006: start make program
*/
#include <stdio.h>
#include <stdlib.h>
#define	 pixel 6378
#define	 line  5562
FILE	*fpi, *fpo;
/* open file sub-rutine */
int	open_file(inname, outname)
char	*inname, *outname;
{
	if((fpi = fopen(inname, "rb")) == NULL){
		printf("don't open %s!\n", inname);
		return(-1);
	}
	if((fpo = fopen(outname, "wb")) == NULL){
		printf("don't write %s!\n", outname);
		return(-1);
	}
return(0);
}
/* main */
int	main(argc, argv)
int	argc;
char	*argv[];
{
int	i,j;
signed short input[pixel];
unsigned char output[pixel];
float	dummy;

	if(argc !=3){
	printf("Usage: program [input] [output]\n", argv[0]);
	exit(-1);
	}
	open_file(argv[1], argv[2]);
	/* read & write 1line each */
	for(i=0;i<line;i++){
	fread (input, sizeof(signed short), pixel, fpi);
		for(j=0; j<pixel;j++){
			if(input[j]==0){
			output[j]=0;
			}
			if(input[j]>0){
			if(input[j]<51){
			dummy=(float)(input[j])*2;
			output[j]=(unsigned char)dummy;
			}
			}
                        if(input[j]>50){
                        if(input[j]<101){
                        dummy=(float)(input[j]-50)+100;
                        output[j]=(unsigned char)dummy;
                        }
                        }
                        if(input[j]>100){
                        if(input[j]<201){
                        dummy=(float)((input[j]-100)*0.5)+150;
                        output[j]=(unsigned char)dummy;
                        }
                        } 
                        if(input[j]>200){
                        if(input[j]<401){
                        dummy=(float)((input[j]-200)*0.125)+200;
                        output[j]=(unsigned char)dummy;
                        }
                        }
                        if(input[j]>400){
                        if(input[j]<801){
                        dummy=(float)((input[j]-400)*0.005)+225;
                        output[j]=(unsigned char)dummy;
                        }
                        }
			if(input[j]>800){
			output[j]=253;
			}
		}
	fwrite(output, sizeof(unsigned char), pixel, fpo);
	}
return(0);
}