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This little program runs with python 3.5 using OpenCV 3.0 and compares image frames from an AVI file, displaying the difference image in a window. The differences are just scaled to fit, but you can come up with all kinds of variations on this.

import numpy as np
import cv2

# Capture video from file
cap=cv2.VideoCapture('/data/Code/Python/AAT/sim_imagery.avi')

old_frame = None

while True:

    ret, frame = cap.read()

    if ret == True:

        gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

        if old_frame is not None:
            diff_frame = gray - old_frame
            diff_frame -= diff_frame.min()
            disp_frame = np.uint8(255.0*diff_frame/float(diff_frame.max()))
            cv2.imshow('diff_frame',disp_frame)
        old_frame = gray

        if cv2.waitKey(30) & 0xFF == ord('q'):
            break

    else:
        print('ERROR!')
        break

cap.release()
cv2.destroyAllWindows()