f=imread('cameraman.tif');
imshow(f);
f1=fftshift(f);
g=abs(f1);
imshow(g,[]);
f=imread('cameraman.tif');
f=im2double(f);
imshow(f);
h = fspecial('average',[9 9]);
g1=imfilter(f,h);
figure,imshow(g1)
h = fspecial('average',[15 15]);
g2=imfilter(f,h);
figure,imshow(g2);