Thanks for the PR! I guess this would be accessed through: mesh.visual.material.kwargs['file_name']? That seems like it could be a little ambiguous, what if just added it on as a runtime patch value which isn't the greatest but is probably a little clearer:

img = Image.open(util.wrap_as_stream(file_data))
# add the file name on as a runtime attribute
img.file_name = file_name
material["image"] = img

I was also thinking about making a class LazyImage(PIL.Image) which didn't actually load the image until it was accessed, maybe at some point in the future.

Actually PIL.Image has a .info dict, I put it there and added a test:
assert m.visual.material.image.info["file_path"].endswith("fuze uv.obj")

Thanks for the PR!

Was away for a bit, just saw you merged my PR, thank you! To answer your previous question (though not needed anymore) yeah I think it's better to keep the raw "map_kd" key value like it's already done for the other MTL keys, rather than just change the "image".

And thank you for the second change too, I may actually use that one :)