image_write( img, filename, ext )

function image_write( img, filename, ext )

% Convert image to double
img = double( img );

% Normalize image between zero and one
img = img - min( img(:));
img = img / max( img(:));

% Write out normalized image
if ~exist( 'ext', 'var' ) || isempty( ext )
  imwrite( img, filename )
else
  imwrite( img, filename, ext );
end

return;