diff.py

import cv2

cap = cv2.VideoCapture(0)

final_frame = None
initial_frame = None

while True:
    # Capture frame-by-frame
    ret, frame = cap.read()

    # Our operations on the frame come here
    final_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    if initial_frame is not None:
        diff = cv2.absdiff(initial_frame, final_frame)

        cv2.imshow('frame', diff)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    initial_frame = final_frame

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()