Mean Filter Image Processing

//Mean Filter Image Processing
>> img=imread('cameraman.tif');
>> imgDouble=im2double(img);
>> filter_1=ones(3,3)/9;
>> filter_2=ones(5,5)/25;
>> appFilter1=filter2(filter_1,imgDouble);
>> appFilter2=filter2(filter_2,imgDouble);
>> subplot(1,3,1), imshow(img);
>> subplot(1,3,2), imshow(appFilter1);
>> subplot(1,3,3), imshow(appFilter2);