Formats in pymaging are represented as
pymaging.formats.Format instances. To make your own format, create an
instance of that class, giving a method to decode, a method to encode and a list of extensions for this
format as arguments.
The decoder function takes one file-like object as argument. It should return
None if the file object passed in is
not in the format handled by this decoder, otherwise it should return an instance of
help with image objects, see About Image objects.