I've just had an e-mail from My Heritage about the introduction of PhotoDater, an AI based app. It suggests that dating of old photos can be done by comparison with existing dated pics.
Today we’re excited to announce the release of PhotoDater™, a groundbreaking, free new feature that estimates the year a photo was taken, using Artificial Intelligence (AI) technology.
PhotoDater™ is one-of-a-kind: MyHeritage is the only genealogy service that offers date estimation for historical photos. Using powerful technology developed by our AI team, PhotoDater™ gives its best guess when a photo was taken. This can help you unlock further clues about who appears in the photo and the event at which it was taken, to solve mysteries in your genealogy research. PhotoDater™ is completely free!
I've not investigated it but though it would make an interesting discussion point:
http://www.rootschat.com/links/01sl9/Gadget