Board Thread:Support Requests - Getting Technical/@comment-4536091-20130815224326/@comment-4018164-20130816054059

Request this in Special:Contact/feedback, but i assume they only allow PNG files as JPG files might get a really bad quality due to large compression.

For now you can use an online convertor like this one to convert your image to .png. If you're using GIMP you can also open any JPG file and save it with a suffix of .png, which would be much shorter.