The python module "CoreImage" is not part of PyObjC, but is a library from Apple that is only available in /usr/bin/python.
That library uses private system APIs and can therefore not easily be ported to other python versions.
Issue #20 is about rewriting that library on top of PyObjC.
The CoreImage APIs themselves are part of PyObjC, and can be accessed using "import Quartz". That uses the same API structure as the C API, which is different from the API exposed in the python library "CoreImage".