function canny_edge()

I = imread('house1-2down.jpg');
subplot(3,3,1); imshow(I); title('Original image')
I = rgb2gray(I);
for i = 2:9
subplot(3,3,i); imshow(edge(I, 'canny', [0.1 0.1*i]));
title(strcat('low: ', num2str(0.1), '     high: ', num2str(0.1*i)));
end
set(gcf, 'color', 'w');

end