How to subtract area outside of a bounding box?

Hi, I have bounding box that contains a specific object. Now I want to subtract area or all objects outside of my bounding box. I am showing an example here. Could someone help me please?

[Sahar Pordeli Behrouz]

Hi.

When I detect a bounding box my aim is to extract regions around the bounding box (areas not including the box). Do you know how I should do that ?