# Sum modified laplacian operator

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Psk on 22 Oct 2020
Commented: KSSV on 22 Oct 2020
ML(p, q) =| 2I(p, q) − I(p − 1, q) − I(p + 1, q) | + | 2I(p, q) − I(p, q − 1) − I(p, q + 1) | (2.2.6) where, I(p,q) denotes the pixel value located at the position (p,q).
My Image I is of size 256x256. To implement the above line, I am getting a zero index error as I have choosen p=1:256 and q=1:256. How to avoid getting a zero index error?

KSSV on 22 Oct 2020
Edited: KSSV on 22 Oct 2020
for p = 2:255
for q = 2:255
% do what you want
end
end

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KSSV on 22 Oct 2020
You intialize it as 256*256....for the first and last index (1 and 256) you can use only the which has (p,q) and (p+1,q+1) negelcting p-1, q-1.
Or you resize your 256*256 image into a 258*258 using imresize or interp2.
Psk on 22 Oct 2020
But in that case that will be a deviation from the original formula. That is if i don't use (p-1) and q-1 for first and last index.
KSSV on 22 Oct 2020
Then you resize your image into 258*258..