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As we all know that wizarding world and muggle world in Harry Potter is separated. If we go by this logic, is the world in moving portraits in wizarding world different?
I mean the portraits have knowledge. People in portraits, though dead have capacity to make decisions. So if compared with real life situation, these photographs are not videos or GIFs programmed to move in a specific loop. The people in portraits can move from one frame to another. Also, the background seems alive in many portraits.
From this I assume, there must be another world separated, where the people in portraits live. Something like we see in Wreck-It Ralph. Outside the frame where people can't see, they must have bedroom, living room or maybe a whole garden.
(P.S.: I'm not speaking about photographs in wizarding world's newspaper or wanted posters. They look like looping GIFs.)