HED safe_step question?

[MOstroukhov]

Hi!

I've already asked this question in another repo but not sure if it is the right place, so sorry for crossposting.
I've noticed that in version v1.1 safe_step was implemented for hed detector to avoid "hiding of corrupted grayscale image". Unfortunately I can't find the origin of that problem or any discussion about it? Can someone please point out where to read about that issue?