Mask preprocessing

[Paracetamol56]

Hello, I have a feature request regarding mask preprocessing.

I would like to suggest the implementation of a mask preprocessing feature.

In some cases, the raw mask generated by the model may require additional refinement or modifications (e.g., thresholding, or dilation/erosion).

Would love to hear your thoughts on this and discuss the potential implementation further.

Thanks for your work on this repo!