outpainting seems to be the same as inpainting

[ysig]

Hi,

I think I may found a small bug in the visualization part of ddpm.

Except the case where the mask changes in the sample_log function (which from what I've seen is not the case) in order to have outpainting the mask should be inverted to 1-mask, when given to the sample_log one function.

However lines 1333 and 1342 seem to be identical.