Selecting the right area

[HuimingCheng]

The problem now is that we might need to adjust the area to crop out from the answer sheet based on the templates which means we are going to need to detect multiple rectangles(hopefully they are rectangles) and pick one that is the actual answer area. The program we have now only gives out one contour and we cannot determine which rectangle contour it returns. It's good enough to detect the answer sheet but not for the further image processing.