I have often wondered how common this might be, especially in children. I can remember as a child how following selection to be in the school Nativity play, I realised that I could recall the entire script after just two readings readings. I would try to remember what the script said, rather I just pictured the pages and read the script from the pages. What was interesting to me was how one of the other children in the play did the same thing. Later at age 12, we were talking what a shame it was that we could no longer do this. Possibly owing to changes arising from growth development, or maybe simply through lack of practice.
"One of Stephen's extraordinary abilities is to memorize landscapes up to the highest detail. During this flight he had a thorough look at the view of the Japanese capital from the helicopter including thousands of buildings, towers, high-ways, cars, buses, even down to intricate details of trees and windows. Following the 30 minutes ride Stephen seemed to be very excited and ready for the challenge."
"Kaavya Syndrome - The accused Harvard plagiarist doesn't have a photographic memory. No one does." By Joshua Foer
Here is an interesting article challenging the existence of photgraphic memory that may also explain the phenomena I noticed as a child:
Quote: "Photographic memory is often confused with another bizarre—but real—perceptual phenomenon called eidetic memory, which occurs in between 2 and 15 percent of children and very rarely in adults. An eidetic image is essentially a vivid afterimage that lingers in the mind's eye for up to a few minutes before fading away. Children with eidetic memory never have anything close to perfect recall, and they typically aren't able to visualize anything as detailed as a body of text."
Another article challenging the existence of photographic memory: http://washingtontimes.com/metro/20031001-101117-6490r.htm
Quote: Experts suggest that children lose the ability for eidetic imagery as they grow older because they learn to store information in better ways, Mr. Searleman says. Because a person doesn't have to process what is being viewed with eidetic imagery, it is essentially an inefficient way of remembering details.
"Mentally retarded people tend to have eidetic imagery more often than you'd expect," Mr. Searleman says. "If you're mentally retarded, you don't have access to more sophisticated ways of encoding information."