Question about the implementation of function ignores_from_label in layers.py

[xychenunc]

I was trying to understand how you implement AAF. However, I found it difficulty to understand how it exactly works. Specifically, I am not sure what do you mean in the comments of ignores_from_label by stating that 'Retrieve eight corner pixels from the center, where the center is ignored. Note that it should be bi-directional'. Why it should be bi-directional?

Thanks in advance for your help!