/***************************************************************************
 * File: arithlut.c                                                        *
 *                                                                         *
 * Desc: This program performs arithmetic point operations via LUTs        *
 ***************************************************************************/


#include <stdio.h>
#include <string.h>
#include <alloc.h> 
#include "ip.h"

#define operation(VALUE)        ((float) VALUE * 1.9)

extern void write_pnm(image_ptr ptr, char filein[], int rows,
		      int cols, int magic_number);
extern image_ptr read_pnm(char *filename, int *rows, int *cols,
		      int *type);

int main(int argc, char *argv[])
    {
    char filein[100];                   /* name of input file */
    char fileout[100];                  /* name of output file */
    int rows, cols;                     /* image rows and columns */
    unsigned long i;                    /* counting index */
    unsigned long bytes_per_pixel;      /* number of bytes per image pixel */
    unsigned char LUT[256];             /* array for Look-up table */
    image_ptr buffer;                   /* pointer to image buffer */
    unsigned long number_of_pixels;     /* total number of pixels in image */
    int temp;                           /* temporary variable */
    int type;                           /* what type of image data */


    /* set input filename and output file name */
    if(argc == 3)
	{
	strcpy(filein, argv[1]);
	strcpy(fileout, argv[2]);
	}
    else
	{
	printf("Input name of input file\n");
	gets(filein);
	printf("\nInput name of output file\n");
	gets(fileout);
	printf("\n");
	}

    buffer = read_pnm(filein, &rows, &cols, &type);

    /* initialize Look-up table */
    for(i=0; i<256; i++)
	{
	temp = operation(i);
	CLIP(temp, 0, 255);
	LUT[i] = temp;
	}

    /* determine bytes_per_pixel, 3 for color, 1 for gray-scale */
    if(type == PPM)
	bytes_per_pixel = 3;
    else
	bytes_per_pixel = 1;

    number_of_pixels = bytes_per_pixel * rows * cols;

    /* process image via the Look-up table */
    for(i=0; i<number_of_pixels; i++)
	buffer[i] = LUT[buffer[i]];

    write_pnm(buffer, fileout, rows, cols, type);
    IP_FREE(buffer);
    return 0;
    }