image_name = mGetLeftImageFileList;

bin_total = 2^8;	   
	   
zero_bin = zeros( 1, bin_total );
Hu0_total = 0;

for image_count = 1:size(image_name,1);
  image_file = deblank( image_name( image_count,: ) )
  image = pgmRead( sprintf( '../images/%s',image_file ) );
  
  % ignore coding for first column -- valid results only
  
  image_filter = [ -1 1 ];
  image = filter2( image_filter, image, 'valid' );

  [ row_total, col_total ] = size( image );
  
  % errors below zero are shifted up by 256, ie wrapped around so that
  % the reconstruction will be correct, eg:
  % e = s0 - s1 = 255 - 0 = 255 
  % then
  % s0 = s1 + e = 0 + ( 255 ) = 255
  % or:
  % e = s0 - s1 = 0 - 255 = -255 = 1 
  % then
  % s0 = s1 + e = 255 + ( 1 ) = 256 = 0
  
  bin = zero_bin;
  for row = 1:row_total
    for col = 1:col_total
      bin_index = image( row, col );
      if bin_index < 0
	bin_index = bin_index + 257;  % +256 to wrap, +1 for valid index
      else
	bin_index = bin_index + 1;    % 0 not a valid index
      end
      bin( bin_index ) = bin( bin_index ) + 1;
    end
  end
  

  % Normalize to find pdf
  PDF = bin/sum(bin);
  
  % x*log(x) = log(x^x)
  PlogP = log(PDF.^PDF)./log(2);
  
  Hu0 = -sum( PlogP )
  
  Hu0_total = Hu0_total+Hu0;
end


% Overall statistics:

sprintf( 'Combined images:' )

Hu0 = Hu0_total/size(image_name,1)