Houghpeaks function in Hough transform ( matlab code )

Question

Look at the houghpeaks function for Hough transform in matlab toolbox:

peaks = houghpeaks(H, numpeaks)

peaks = houghpeaks(..., param1, val1,param2, val2)

paramter:

'NHoodSize' : Two-element vector of positive odd integers: [M N].

Question: NHoodSize must be odd? why?

Answer 1

Wouldn't that be because otherwise you're not landing on a cell boundary?

1 2 3
4 5 6
7 8 9

vs.

1 2
3 4

In NHOOD calculations an element in the middle is being evaluated and somehow being influenced by the surrounding values.