% grapple.m loads and displays grapple.gif, then performs median filtering

G = imread('grapple.gif');           % read the .gif file

class(G)                             % is G double or uint8?

subplot(2,2,1)
imshow(G,[0 1]);                     % display the image with 2 gray levels
title('Original image')
drawnow
for i=1:3,
  G = medfilt2(G,[5 5]);
  subplot(2,2,i+1)
  imshow(G,[0 1]);
  title('After median filtering');
end