@dansup to save you some time when writing the porn detection, Fred Colon, of Ankh Morpork City Watch fame, has you covered* with the classification rules.

"Nude women are only Art if there’s an urn in it,” said Fred Colon. This sounded a bit weak even to him, so he added: “Or a plinth. Both is best, o’course. It’s a secret sign, see, that they put in to say that it’s Art and okay to look at." -Thud, Terry Pratchett's #Discworld

*no pun etc...