Confused about the spatial centering implementation

[aliasvishnu]

As per my understanding, in this code for spatial centering, the operation fd -= fd.mean([3, 4], keepdim = True) should have been enough.

Can you please correct my understanding/offer intuition into this segment of code - especially why fd = fd - fd.mean() + old_mean is done? Thank you.

[YBYBZhang]

I have the same question !

[mhamilton723]

It's been a little while but IIRC its so that you dont change the aggregate strength of the signal, aka the full mean (here old_mean). We still want positives to be more strong of an attractive force than negatives and this operation makes sure the aggregate strength remains unchanged