function PNGViewer(dirName)
% open png directory
fprintf('%s\n', dirName)
listing = dir([dirName '*.png']);

colormap(winter);
for t = 1:length(listing)
    frame = imread([dirName listing(t).name]);
    imagesc(imadjust(double(frame)/10000)); axis equal; axis off;
    title([listing(t).name ' frame:' num2str(t)]);
    drawnow;
end