How to find the neighbourhood of a pixel

How to find a particular pixel and the neighbourhood of it?

Answer 1

[Andrei Bobrov]

try this code (need have Image Processing Toolbox)

I = rand(10) > .9 % initial array
out = imdilate(I,ones(3)) - I;

OR

out = bwmorph(I,'dilate')-I

OR

out = bwdist(I,'chessboard') == 1;