How to automatically align an image

[robrod26]

I have dozens of images of this coin at various rotations (34, 120, 170, etc. degrees). What would be the easiest and best way in Python to automatically straighten the images so they are "aligned" as shown in the image below?

[ThomasL]

The easiest and best way doesn't always match, so I'd replace the "and" with an "or".

I don't know either, but I would try a convolutional neural net. (Machine learning / AI)