clear all;

% Setup data

left_image_list = mGetLeftImageFileList;
right_image_list = mGetRightImageFileList;
	   
image_pair_total = size( left_image_list, 1 );

Hu0_total = 0;
image_size_total = 0;


for image_count = 1:image_pair_total
  left_image_name = deblank( left_image_list( image_count,: ) )
  right_image_name = deblank( right_image_list( image_count,: ) )
  left_image = pgmRead( sprintf( '../images/%s', left_image_name ) );
  right_image = pgmRead( sprintf( '../images/%s', right_image_name ) );
  
  diff_image = right_image - left_image;
  diff_max = max( max( abs( diff_image ) ) );
  diff_offset = -diff_max - 1;
  
  [ row_total, col_total ] = size( left_image );
  image_size = row_total*col_total;
  
  bin = zeros( 2^8, 2*diff_max + 1 );
  for row = 1:row_total
    for col = 1:col_total
      bin_row_index = left_image( row, col )+1;
      bin_col_index = diff_image( row, col )-diff_offset;
      % zero is not a valid index -> add 1
      bin( bin_row_index, bin_col_index ) = bin( bin_row_index, bin_col_index ) + 1;
    end
  end
  
  % Normalize to find pdf
  PDF = bin / sum( sum( bin ) );
  
  if image_count == 1  % display joint histogram for first image
    mPlotJointPDF( [ left_image_name ', ' right_image_name ], ...
	           'Left image pixel', [ 0:255 ], ...
	           'Difference', [ -diff_max:diff_max ], ...
		   'MPD', PDF );
p2=PDF;	       
  end

  % x*log(x) = log(x^x)
  PlogP = log( PDF.^PDF)/log(2);
  
  Hu0 = -sum( sum( PlogP ) )
  Normalized_Hu0 = Hu0/2
  
  Hu0_total = Hu0_total + Hu0;
  image_size_total = image_size_total + image_size;

end


% Overall statistics:

fprintf( 2, 'Combined images:\n' )

% Normalize to find pdf
Average_Hu0 = Hu0_total/size( left_image_list, 1 )

Normalized_Average_Hu0 = Average_Hu0/2