Sobel and Canny Edge Detection

//Sobel and Canny Edge Detection
>> clear all
>> f=imread('cameraman.tif');
>> bw1=edge(f,'sobel');
>> bw2=edge(f,'canny');
>> subplot(1,3,1), imshow(f), title('Original Image');
>> subplot(1,3,2), imshow(bw1), title('Sobel Edge Detecteion');
>> subplot(1,3,3), imshow(bw2 ), title('Canny Edge Detecteion');