displayImages.m

function [h, display_array] = displayImages(X)
%DISPLAYIMAGES Display images in X in a grid shape
%   [h, display_array] = displayImages(X) displays images stored in X in 
%   a grid. It returns the figure handle h and the displayed array.

% Gray Image
colormap(gray);

% Compute rows, cols
[m n] = size(X);
example_width = round(sqrt(size(X, 2)));
example_height = (n / example_width);

% Compute number of items to display
display_rows = floor(sqrt(m));
display_cols = ceil(m / display_rows);

% Between images padding
pad = 1;

% Setup blank display
display_array = - ones(pad + display_rows * (example_height + pad), ...
                       pad + display_cols * (example_width + pad));

% Copy each example into a patch on the display array
curr_ex = 1;
for j = 1:display_rows
	for i = 1:display_cols
		if curr_ex > m, 
			break; 
		end
		% Copy the patch
		
		% Get the max value of the patch
		max_val = max(abs(X(curr_ex, :)));
		display_array(pad + (j - 1) * (example_height + pad) + (1:example_height), ...
		              pad + (i - 1) * (example_width + pad) + (1:example_width)) = ...
						reshape(X(curr_ex, :), example_height, example_width) / max_val;
		curr_ex = curr_ex + 1;
	end
	if curr_ex > m, 
		break; 
	end
end

% Display Image
% TEMPORARY FIX FOR FLIPPED IMAGES BEING SHOWN IN GNUPLOT
% -if your images are displayed upside down, uncomment the following
display_array = flipdim(display_array,1);
h = imagesc(display_array, [-1 1]);

% Do not show axis
axis image off

drawnow;

end