[Psychlist]

People can have absolute/exception memory for other things too. I dated a woman who could look at a bit of cloth and say "that's the same colour as..." and be right every time. Even when she hadn't seen the other item of clothing for months. It made shopping with her somewhat less painful because she wasn't constantly swapping things just to look at the colours.

Much better than perfect pitch, otherwise known as the ability to know that something is out of tune, by how much, and struggle to ignore that. A violinist friend managed to train herself to shift pitch to match the rest of the orchestra but I suspect part of the reason she turned to the dark side (jazz) was the latter's ability to adapt to her sense of correct pitch.