Adelson checkerboard illusion

edit

I went through this post which tries to implement the illusion in OpenCV.

Processing images causing optical illusions

I am unable to reproduce the result posted on the link. Am I missing some part of the code here? As it has been mentioned that this is a small fragment of python code they tested.

Looking for some guidance.

I am currently counting of this illusion to help me extract edges.

Example picture:

Extraction of edge of this single potato

I tried to extract the edges

At the bottom of the original potato image you can see, we can clearly trace out the edge from our eye. When edge detection is applied it can't even be detected at a narrow threshold at lower limit.

Any suggestions on how to detect the edge being missed by the edge detector?