input is block 16x16 block=16x16 (piece of image)
i found S(x,y) making kernel[1 1 1; 1 1 1; 1 1 1] convolution with block
for i=1:1:14
for j=1:1:14
for m=-1:1
for n=-1:1
S(i+1,j+1)=S(i+1,j+1)+kernel(m+2,n+2).*blok(i-m+1,j-m+1);
end
end
% S=blok(i-1:i+1;j-1:j+1);
total=total+abs(blok(i+1,j+1)-S(i+1,j+1));
end
end
its seems work for now but ı am not sure.