Vision: [Feature Request] Un-Normalize Image Tensor

[varagrawal]

Basically the inverse of transforms.Normalize as this will allow us to visualize tensors during training more easily.

[karandwivedi42]

https://github.com/pytorch/vision/issues/281

[fmassa]

I agree with @karandwivedi42 and the comment that he linked to.

If you want to reverse the normalization, all you need to do is to use a new normalization, with slight modifications:

mean = torch.tensor([1, 2, 3], dtype=torch.float32)
std = torch.tensor([2, 2, 2], dtype=torch.float32)

normalize = T.Normalize(mean.tolist(), std.tolist())

unnormalize = T.Normalize((-mean / std).tolist(), (1.0 / std).tolist())

EDIT: fixed thanks to @karandwivedi42 comment

[fmassa]

Thanks @karandwivedi42 , my bad!
I'll fix my comment!