This is a collection of code to process images in python using numpy and matplotlib.
http://scikit-image.org/docs/dev/user_guide/numpy_images.html
If you are really lost in signal and image processing and want to have a good start into the topic, I can really recommend the book "A computational introduction to digital image processing" from Alasdair McAndrew, which contains explanation at a simple mathematical level as well as code templates for Matlab/Octave and Python.