MATLAB: Calculating the neighbour values

matrix

i have a matrix
A=[1 2 3
   4 5   6
   7  8  9  ]
please tell how to calculate the neighbour values of centre pixel

Best Answer

A = [    542         605         341         615         928
         471         550         839        1185         315
         945         798         809         421         625
         982         876         201         723         863
         231         932         147         277        1100]; %initial matrix
out1 = cell(numel(A),1);
q = false(size(A));
for ii = 1:numel(A)
    w = q;
    w(ii) = true;
    w1 = imdilate(w,[1 1 1;1 0 1;1 1 1]);
    out1{ii} = A(w1);
end
% other variant
B = padarray(A,[1 1],nan);
s = size(B);
addm = bsxfun(@plus,(0:2)',(0:2)*s(1));
ad = addm(:)';
C = reshape(1:prod(s),s);
C = C(1:end-2,1:end-2);
out2 = B(bsxfun(@plus,C(:),ad([1:4,6:9])));
% the centre pixel values is 809 and has index:
i1 = 13;
out1{i1}
ans =
         550
         798
         876
         839
         201
        1185
         421
         723
>> out2(i1,:)
ans =
         550         798         876         839         201        1185         421         723
>>
Related Question