This is a basic transform question in PIL. I\'ve tried at least a couple of times in the past few years to implement this correctly and it seems there is something I don\'t
I think this should answer your question.
If not, you should could consider that affine transformations could be concatenated into another transformation.
So you could split your desired operation into:
Moving the orgin to center of the image
Rotating
Moving the origin back
Resizing
You could than compute a single transformation out this.