Can you see the letter that is made out of the red dots when you combine both of these pictures?
It's apparently hard for most people, almost impossible even (though not for this author who just discovered they have a photographic memory).
This purportedly difficult challenge is just one of the trials in a quiz which aims to find out whether you have a photographic memory.
The real term for people who can recall images after brief exposure is called "eidetic memory". Actual "photographic memory" has never been found to exist, with some cognitive scientists calling it a myth.