fancy threshold to intake max foreground

[dsundarraman]

Modified fancy threshold function to incorporate max foreground to clip hist beyond these values. Default value 0.0 not ideal but should work for the application.

[JoOkuma]

Thanks for the PR @dsundarraman, I left a few minor comments

[JoOkuma]

Hi @ilan-theodoro, thank you for the fix.

I would suggest using the dispatch mechanism from numpy and avoiding importing the libraries as xp unless it's really necessary.
https://github.com/royerlab/dexpv2/blob/main/dexpv2/crosscorr.py is a good example of how most functions are implemented in dexpv2.

I understand that this is a cupy only fix, so it might be worth adding a function is_cupy_array to dexpv2.cuda, and even replacing this section of the code

dexpv2/dexpv2/cuda.py

Lines 137 to 138 in d13e1e0

	elif cp is not None and isinstance(arr, cp.ndarray):
	arr = arr.get()

This would simplify the typing.

It might be useful the fact that, np.float16 == cp.float16