Making background element out of a part of a video I have this shot which has the right door color corrected to make it look dark and red :



How would I go about making it part of the "background" so that when someone comes in front of it, he is not affected by the correction like in the shot below :



I tried looking into Masks as background or 3D layers but couldn't seem to find what I'm looking for. I'm sure it's an easy thing to do but I just need guidance on what to look / search for.
You need to rotoscope every object in front of your "background". There is not simple solution, because AE cant tell the difference between you foreground and background. Even I can't tell, because people drop shadows on your "background", etc.

You can try to use rotobrush for that, but if you have there a lot of people, it will require a lot of work.