Photographic or eidetic memory is, so they say, probably a myth. They catch it in kids once in a while, and that’s about it.
The thing is though, both hub and myself had it as kids, and still have it at times well into adulthood. Not only that, but each of us has a few specific ‘eidetic memory’ type of memories that have lasted since childhood (most of them fade away after a while, but you still have the memory of the memory, if that makes sense—if not it might when you’re done reading this).
Naturally, this means I have some of my own guesses and hypotheses about how it works and whether or not it can be learned. I might be able to teach you how to have your own eidetic memories.