Add tif support

[kdionyso]

This small modification allows .tif files to be read in and used for training/validation/testing. The modification is pretty small and I hope it can be incorporated into master. This will help the remote sensing community to use the timm package for model training. If necessary I can write a small test to demonstrate that it works with .tif files.

[rwightman]

@kdionyso not opposed to adding, but one issue with tiff, aren't both .tif and .tiff equally common or do you find .tif is most used?

[kdionyso]

Apologies for the very very tardy reply, @rwightman. I believe that ".tif" files are more common in the remote sensing/earth observation community and this is why I recommended adding that capability. There are possibly use cases for ".tiff" files as well, but to be honest I have not come across files with this extension in my line of work. Awesome work by the way :)

[VarIr]

It seems .tiff would be the canonical form, judging from specification names: "TIFF/EP (ISO 12234-2), TIFF/IT (ISO 12639),[3][4][5] TIFF-F (RFC 2306) and TIFF-FX (RFC 3949).[6]" (from https://en.wikipedia.org/wiki/TIFF).

In any case, our microscopes create .tiff files (biomedical domain).

[metazool]

Sounds like it's safest to include both. It would be very useful to us

[rwightman]

@VarIr @metazool @kdionyso
I decided to support this a different way, let people change the defaults. So I'll keep the defaults as is for now, but you can easily change them now (before you create a dataset/parser and initiate the file scan).

>>> timm.data.get_img_extensions()
('.png', '.jpg', '.jpeg')
>>> timm.data.add_img_extensions(['.tif', '.tiff'])
>>> timm.data.get_img_extensions()
('.png', '.jpg', '.jpeg', '.tif', '.tiff')
>>> timm.data.set_img_extensions(['.tif', '.tiff'])
>>> timm.data.get_img_extensions()
('.tif', '.tiff')
>>> timm.data.del_img_extensions('.tiff')
>>> timm.data.get_img_extensions()
('.tif',)

bfc0dcc

EDIT this will be merged later today / tomorrow