/*	subset_image.c
**	    This program is used to subset a raw image file
**      (i.e. containing of no header)
**      (sometimes such images also called generic binary image)
**      
*/

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

main()
{
  FILE 		*fin, *fout;
  unsigned int img_row;
  unsigned int img_col, step;
  int sub_col, sub_row, x_up, y_up, x_low, y_low;
  int count1, count2;
  unsigned char *store, *sub_row_start, in_file[50], out_file[50];

      printf("\n====Subset an image====\n");
	  printf("Please input the number for image rows:");
      scanf("%d",&img_row);
	  printf("Please input the number for image columns:");
      scanf("%d",&img_col);
	  printf("Please input upper left co-ordinates for subset starting point:");// img_width = atoi(argv[4]);
      printf("x=");
	  scanf("%d",&x_up);
      printf("y=");
	  scanf("%d",&y_up);
	  printf("Please input down right co-ordinates for subset ending point:");// img_width = atoi(argv[4]);
      printf("x=");
	  scanf("%d",&x_low);
      printf("y=");
	  scanf("%d",&y_low);
	  
      printf("Input image file:");
	  scanf("%s",in_file);

	  if((fin = fopen(in_file,"rb")) == NULL)
	  {
	  printf("Failed to open %s\n",in_file);
	  exit(EXIT_FAILURE);
	  }
     
      printf("Ouput image file:");
	  scanf("%s",out_file);

	  if((fout = fopen(out_file,"a")) == NULL)
      {
      printf("Failed to open %s\n",out_file);
      exit(EXIT_FAILURE);
      }

	  printf("Input completed, start calculating...\n"); 
      sub_col = x_low - x_up + 1;
      sub_row = y_low - y_up + 1;
      store = (unsigned char *)malloc(img_col);
      sub_row_start = (unsigned char *)malloc(sub_col);

      for(count1 = 0; count1 < y_up; count1++)
  	  fseek(fin,img_col,1);
      if(x_up != 0)
        fseek(fin,x_up,1);
      step = img_col-sub_col;
      for(count2 = 0;count2 < sub_row; count2++)
	 {
          fread(sub_row_start,1,sub_col,fin);  
	      fwrite(sub_row_start,1,sub_col,fout);
          fseek(fin,step,1);
	 }
	
      fclose(fin);
      fclose(fout);
      free(store);
      free(sub_row_start);
      printf("\n===Running completed!\n");
	  printf("\nImage %s with row = %d, column = %d!\n",out_file, sub_row, sub_col);
}