You are compositing greenscreen footage that was poorly lit. The corners of the green footage are dark. The subject is in the center of the frame, and you want to remove the dark corners to make the…

You are compositing greenscreen footage that was poorly lit. The corners of the green footage are dark. The subject is in the center of the frame, and you want to remove the dark corners to make the green screen key easier to achive. Which filter should you use to help crop the corners of the green screen footage?