Filtro de la Media

I=imread('2.jpg');
k=I(:,:,1);
imshow(k);
[m,n]=size(k);
for i = 2:m-2
for j=2:n-2
a=double((k(i-1,j-1)+k(i-1,j)+k(i-1,j+1)+k(i,j-1)+k(i,j)+k(i,j+1)+k(i+1,j-1)+k(i+1,j)+k(i+1,j+1))/9);
k(i,j)=ui;
end
end
figure
imshow(k)