/* fix_th.c */
#include <stdio.h>
#include <stdlib.h>
#include "mypgm.h"

#define BLACK 0
#define WHITE 255

void fixed_threshold()
     /* binarization by fixed threshold */
     /* input image1[y][x] ===> output image2[y][x] */
{
  int min, max; /* maximum & minimum graylevels */
  int mean;     /* mean value of graylevels */
  double sum;
  int x, y;     /* Loop variables */
  int threshold; /* threshold value for binarization */
  
  /* detection of maximum, minimum & mean  values of gray levels */
  min = max = image1[0][0];
  sum = 0.0;
  for (y = 0; y < y_size1; y++) {
    for (x = 0; x < x_size1; x++) {
      sum += image1[y][x];
      if (image1[y][x] < min) min = image1[y][x];
      if (image1[y][x] > max) max = image1[y][x];
    }
  }
  mean = (int)(sum / (x_size1 * y_size1));
  printf("Minimum graylevel = %d --- Maximum graylevel = %d\n", min, max);
  printf("Mean graylevel    = %d\n", mean);
  printf("\nEnter threshold value of binarization = ");
  scanf("%d", &threshold);
  /* result of binarization based on fixed threshold
     stored into image2[y][x] */
  x_size2 = x_size1;
  y_size2 = y_size1;
  for (y = 0; y < y_size1; y++) {
    for (x = 0; x < x_size1; x++) {
      if (image1[y][x] > threshold) {
	image2[y][x] = WHITE;
      } else {
	image2[y][x] = BLACK;
      }
    }
  }
}

main()
{
  load_image_data();       /* input image1 */
  fixed_threshold();       /* binarization by fixed threshold */
  save_image_data();       /* output image2 */
  return 0;
}