Make io.ImageCollection cross-platform compatible for same path specifier

[stefanv]

Currently, different path separators have to be used on Windows and Linux.

[jni]

to be clear, ImageCollection('*.png:*.jpg') works on *NIX, while ImageCollection('*.png;*.jpg') works on Windows. We should do a find and replace on the input string based on platform. However we have to be careful because : is a valid filename character in *NIX.

[hmaarrfk]

Maybe the solution is to take in a list? ['*.jpg', '*.png']

[stefanv]

https://stackoverflow.com/questions/54659897/skimage-io-imagecollection-not-showing-all-files-i-want-when-using-io-imagecolle

[stefanv]

@hmaarrfk That would be a good solution. @jni If ':' is a valid filename in Unix, our current implementation is already broken. Are semi-colons acceptable in Unix filenames? Or are colons acceptable in Windows filenames? Any of these options allow us to make a fix. But Mark's suggestion is a better long-term solution, I think.

[jni]

@stefanv

 $ ls -l
total 192
-rw-r--r--   1 jni  staff     0B 18 Feb 10:47 ;.txt

=P

I vote for Mark's suggestion. But honestly I agree with the first commenter that it's not a bug, and we should continue using os.pathsep even after we implement lists. It is an internally consistent solution.

[stefanv]

You can decide not to call it a bug, but I think the many users who simply write `ImageCollection('some_glob:another_glob')` won't benefit from such an assessment.

[jni]

I agree 100% (see my comment about our low dynamic range warnings), but I don't think the solution is to break the os.pathsep convention. Mark's suggestion is easy to remember and unambiguous.

[stefanv]

Agreed, that is a better API.