Different gradient edge detection operator MATLAB

Direct offer code, we can see understand
CLC, Clear;
the I = imread ( 'pout1.tif');
imshow (the I);
title ( 'original');
BWl = Edge (the I, 'Roberts');
BW2 = Edge (the I, 'Prewitt');
BW3 = Edge (the I, 'Sobel');
BW4 = Edge (the I, 'log');
BW5 = Edge (the I, 'Canny');
Figure, imshow (BWl, [ ]);
title ( 'Roberts');
Figure, imshow (BW2, []);
title ( 'Prewitt')
Figure, imshow (BW3, []);
title ( 'Sobel')
Figure, imshow (BW4, [] );
title ( 'log')
Figure, imshow (BW5, []);
title ( 'Canny')

If you do not know where to welcome in the comments below made!