Modifying OpenCV's grabcut implementation to change background

This program can be used to change the background of an image by applying grabcut algorithm.

g++ background-change.cpp -o main `pkg-config --cflags --libs opencv`

./main fg_image bg_image
(where, fg_image is the foreground image, and bg_image is the background image)

This will open the image in a window where you can select foreground and background pixels.
In order to select background pixels, press 'Ctrl' and click+move over the background region. Similarly, in order to select foreground pixels, press 'Shift' and click+move over the foreground region. Once the selection process is completed, press 'n' to perform grabcut.
(Note: Pressing 'n' multiple times will refine the resulting mask)

./main ./data/in1.jpg ./data/in2.jpg

Input images:

Result Image: