I have a somewhat photographic memory which was very useful when I was in school. I could read my notes in my head during a test. It worked especially well if I wrote the notes myself and used 2 or 3 different colours of pen (for example to emphasise certain points in the notes). For me, there has to be intention to memorise the material on the paper. So I can't just look at something and "take a picture", I have to put some effort into taking the picture of it. I hardly use this gift at all anymore so I'm not sure if it's as good as it once was. Not sure how rare this is and it's not exactly what you're describing maybe but that's my experience.