ima=input(:,250:400);
window_size = 6;
wsz = window_size-1;
mp = round(window_size/2);
img = ima;
x1 = zeros(size(img));
y1 = zeros(size(img));

img1 = img;
for k1= 1:size(img,1)-wsz
    for k2= 1:size(img,2)-wsz

        if ima(k1,k2)~=0
            thresh=img(k1:k1+wsz,k2:k2+wsz);
    end
end

figure,imshow(thresh)