Missing invertible 1x1 conv from GLOW

[plutoyuxie]

Hi, I want to rebuild a framework referring to glow. Here I have some doubts:

1. Is 'OrthogonalTransform' equal to the 'invertible 1x1 conv' in glow?

2. If I only want to use addition coupling rather than affine coupling, should I just use NICECouplingBlock instead of GLOWCouplingBlock?

Thanks for help.

[ardizzone]

Hi!

1.)
We currently have not implementation of the invertible 1x1 conv (only the glow coupling, as you know).
We should probably include it, I will try to get it done this this week, keeping track of it here: vislearn/FrEIA-community#3
The OrthogonalTransform is similar to the invertible 1x1, with the difference that the matrix is constrained to the Steifel manifold (in an attempt to do something similar than GLOW with extra guarantees and stability).
But the OrthogonalTransform gives quite bad performance in my experience, especially for images.

2.)
Yes, that is correct! Or, if you prefer, you could set the clamp option of the GLOWCouplingBlock to 0., to get the same behaviour (but it will be slower and have some unused network parameters)

(I'm changing the title to better keep track of the issue)