I don't really understand how this question deserves the right to exist. Obviously if your brain is able to create a perception of something based on input, it must be able to do this with a self-feeding mechanism as well as without input. Seeing and imagining determine each other. It's not that one of them could exist without the other.
As for the other parts, I agree with what has been said.

Light -> Eye -> Brain -> Perception -> Memory

( Memory -> combined/altered <- Memory )^n -> Internal Perception -> simulating External Perception -> dream