The idiom “never judge a book by its cover” warns against evaluating something purely by the way it looks. And yet book covers are designed to give readers an idea of the content, to make them want to pick up a book and read it. Good book covers are designed to be judged.
And humans are quite good at it. It’s relatively straightforward to pick out a cookery book or a biography or a travel guide just by looking at the cover. Read more about Deep Neural Network Learns to Judge Books by Their Covers