I like that idea. Sadly no-one seems to have a database of images of the spines of books. All I'm doing at the moment is pulling the color at (x:5,y:5) from the cover image and using that for the spine. It's not exact but good enough. I think pick either white or black text depending on the color saturation. It's OK in this situation but for generating a poster it'd need to be a lot more refined.