CAPTCHA reader and maker
You can combine these 3 tricks to resolve your problem:


Create your images as string buffers using StringIO. In Python 2 you can import it by: import StringIO; while in Python 3 you can import it by running: import io then use io.StringIO.
Read your images from a string: im = Image.open(io.StringIO.StringIO(buffer))
You can share the images you are interested in across your three modules by making them global variables (How do I share global variables across modules?).