Efficient, differentiable bilateral filter

[charliebudd]

Is your feature request related to a problem? Please describe.
This would be a useful tool to have in the box, both on its own or part of a larger algorithm such as #315

similar issue for more context...
kornia/kornia#702

Describe the solution you'd like
Would be nice to have an implementation which can operate on arbitrary spatial dimensions and channels.
Due to the high computational load I think dropping down to c++ and cuda could be worth the extra work.

[faebstn96]

Thanks @charliebudd for implementing this layer! Does your implementation also offer a way to backpropagate a loss into the spatial and range (color) parameters sigma? Or do you have a hint how to implement that?
I very much appreciate your help.

[charliebudd]

Hi there, the implementation alows for backpropergation of losses into the input tensor, however learning the parameters has not yet been implemented. Feel free to open up a feature request as it is certainly something we should be targeting.

[faebstn96]

Thanks for your very quick reply @charliebudd !