Image processing tools for python

The most basic library is PIL. it provides pretty basic tools for reading,writing and displaying images, some tools for drawing. In terms of image processing it has some functions for cropping, resizing, sharpening images. For more complex operations I found it insufficient.
The library I found to be useful so far is the Python binding for OpenCV. It can be found here. Installing it should not be too difficult, though I could not get it working until I installed the following:
sudo apt-get install python-opencv