why setting evaluate mode in test.lua yeilding black images? about pix2pix HOT 2 CLOSED

Yeah, setting the net to evaluate mode does two things: 1) enables dropout, 2) makes batchnorm use aggregated training set statistics. I'm not entirely sure why it results in black images, but I think it's more due to 1 than to 2 (or possibly the interaction of the two effects).

The goal of enabling dropout during testing was to make the outputs stochastic (though it only has a very minor effect). Also, our strategy was to run the net identically during training and test, to avoid any "domain gap" between the two phases. This makes a big difference for batchnorm. It could be also that the way we used dropout causes a problematic gap if you turn it off at test time.

from pix2pix.

Maybe worth mentioning: if you are creating animations or videos with pix2pix I recommend to un-comment that line and thus disable dropout in test mode. This will give you much better frame-to-frame consistency and reduce flickering a lot.

from pix2pix.