seam finding in image stitching

edit

I am working with code from OpenCV's stitcher class and i got stuck on understanding how seam finder works.

In code, we can see that this algorithm only takes images, corners of images a empty masks

seam_finder_->find(images_warped_f, corners, masks_warped);

what i'd like to know is, that how does this algorithm finds seam in overlapped area? in those parameters we just give him overlapped images, but how does it finds this overlapped area of images and finds seam cut there