read_lbed_file(filename,imagename)  /* read in linked bar-edgel file */
char *filename, *imagename;
{
	int fd;
    	float test;
    	struct stat statbuf;
	float sigma_t, sigma_l, sd_noise;
	int dim0, dim1, edge_type;
	int i;
	int min_length, number_of_edgel;
	int total_edge_number, total_edgel_number;
	int edge_index, edge_length, n, k, EK_vector_number;
	float xi, yi, theta, strength;

	if (stat(filename,&statbuf) != 0)  /* get the file information */
      	{
	  perror(filename);
	  exit(1);
        };

    	if ((fd = open(filename,O_RDONLY)) < 0)
      	{	
	  perror(filename);
	  exit(1);
      	};
    
	INPUT_BUFFER = (unsigned char *) calloc(statbuf.st_size,sizeof(char));
    
    	if (read(fd,INPUT_BUFFER,statbuf.st_size) != statbuf.st_size)
      	{   /* read in the whole file and save it in INPUT_BUFFER
	  perror(filename); 
	  exit(1);
      	};

	INPUT_BUFFER_POINTER = INPUT_BUFFER;

	edge_type = read_1byte_integer();   
	     /* edge_type = 0 (Canny operator) or 1 (Wang-Binford operator) */
	sigma_t = read_single_float();
             /* the sigma of the mask along the transverse direction */
	sigma_l = read_single_float();
             /* the sigma of the mask along the longitudinal direction */
	sd_noise = read_single_float();
	     /* the standard deviation of pixel noise */
	dim0 = read_2byte_integer();     /* number of columns */
	dim1 = read_2byte_integer();     /* number of rows */
	min_length = read_1byte_integer();    /* edge length >= min_length   */
	for(i = 0; i < 110; ++i)         /* header */
	  read_1byte_integer();   
	
	total_edge_number = read_4byte_integer();  /* total number of edges */
	total_edgel_number = read_4byte_integer(); /* total number of edgels */

	for(edge_index = 1; edge_index <= total_edge_number; ++edge_index)
	{
	  number_of_edgel = read_3byte_integer(); /* number of edgels in this edge */
	  for(n = 1; n <= number_of_edgel; ++n)
	  {
	      strength = read_single_float();
	      theta = read_2byte_integer() * 0.0000958738; 
		 /* 9.58738e-5 = 2*pi/65536 */
	      if( dim0 > 512)   /* decode the position information */
	        xi = 0.0078125 * read_3byte_integer();
	      else
	        xi = 0.0078125 * read_2byte_integer();
	      if( dim1 > 512)
	        yi = 0.0078125 * read_3byte_integer();
	      else
	        yi = 0.0078125 * read_2byte_integer();
	  };
	};
}




read_4byte_integer()
{
	int data_1, data_2, data_3, data_4;

	data_1 = *INPUT_BUFFER_POINTER;
   /* INPUT_BUFFER is an I/O buffer and INPUT_BUFFER_POINTER is the pointer */
	INPUT_BUFFER_POINTER += 1;
	data_2 = (*INPUT_BUFFER_POINTER << 8);
	INPUT_BUFFER_POINTER += 1;
	data_3 = (*INPUT_BUFFER_POINTER << 16);
	INPUT_BUFFER_POINTER += 1;
	data_4 = (*INPUT_BUFFER_POINTER << 24);
	INPUT_BUFFER_POINTER += 1;

	return(data_1 + data_2 + data_3 + data_4);
}



read_3byte_integer()
{
	int data_1, data_2, data_3;

	data_1 = *INPUT_BUFFER_POINTER;
	INPUT_BUFFER_POINTER += 1;
	data_2 = (*INPUT_BUFFER_POINTER << 8);
	INPUT_BUFFER_POINTER += 1;
	data_3 = (*INPUT_BUFFER_POINTER << 16);
	INPUT_BUFFER_POINTER += 1;

	return(data_1 + data_2 + data_3);
}



read_2byte_integer()
{
	int data_1, data_2;

	data_1 = *INPUT_BUFFER_POINTER;
	INPUT_BUFFER_POINTER += 1;
	data_2 = (*INPUT_BUFFER_POINTER << 8);
	INPUT_BUFFER_POINTER += 1; 

	return(data_1 + data_2);
}


read_1byte_integer()
{
	int data_1;

	data_1 = *INPUT_BUFFER_POINTER;
	INPUT_BUFFER_POINTER += 1;

	return(data_1);
}


float read_single_float()
{
	/* Use IEEE standard to represent a single-precision number */
	int code, ff, ee, ss;

	code = read_4byte_integer(INPUT_BUFFER_POINTER);
	ff = (code & 037777777);
	ee = ((code >> 23) & 0377);
	ss = ((code >> 31) & 01);

	if (ss == 1)
	  return(-1.0 * powf(2.0,(float)(ee-127)) * (1.0+ff*1.1920929e-7));
	else
	  return(powf(2.0,(float)(ee-127)) * (1.0+ff*1.1920929e-7));

}