Mask to boundary API

[bhack]

🚀 The feature

Expose a mask to boundary API

Motivation, pitch

A mask to boundary API is useful for implementing many segmentation metrics used in many dataset and challenges (Davis F score, BoundaryIOU, etc..).
It could be also used more generally for visualization tasks.
See a gist at:
Lightning-AI/torchmetrics#1500 (comment)

Alternatives

No response

Additional context

No response

[NicolasHug]

Thanks for the proposal @bhack . The implementation looks simple enough and we already have some utils like masks_to_box, so as long as we can properly test it against the opencv reference implementation, it sounds like something we could support. Feel free to submit a PR.

[bhack]

On what file do you want to put it?

[oke-aditya]

You can put it into file https://github.com/pytorch/vision/blob/main/torchvision/ops/boxes.py