But the Sharingan isnt like Polaroid memory, its gives the user the ability to copy and mimic ninjutsu, genjutsu and taijutsu while also remembering everything it sees...
Also, as the pictures in the thread about Itachi's eyesight it shows two pictures that show some of the things a Sharingan does:
While it is doing that it perfectly remembers the things it sees and begins interpreting certain things... (Check out Kakashi after the 4 year gap when he is fighting Sakura and Naruto... he has to cover it eye so it doesnt interpret something Naruto does...((As specific I'm gonna get cus I'm too lazy to change the color of the text to make it a spoiler thing)))
Also, the Sharingan forces the concious part of the brain to read all of this as it happens, not the subconcious, so it is putting more strain on the concious part of the brain...
Also, as you said, Naruto is a work of fiction, so who is to say what is or isnt possible in it?
You can copy and instantly have perfected any genjutsu, taijutsu, and ninjutsu... But the ability to perform it is different. I know EXACTLY how juggling works and how to do it. I still can't. The sharingan (because Naruto is a fictional work) makes it so that you can instantly perform something as well.
Arn't you contradicting yourself? O_o;;
Meh, as I said, I could be wrong, who cares? It's just a theory about an anime