Extract differences between two images using OpenCV in Python

import cv2
import numpy as np

img1 = cv2.imread("img1.png")
img2 = cv2.imread("img2.png")
diff = cv2.absdiff(img1, img2))
mask = cv2.cvtColor(diff, cv2.COLOR_BGR2GRAY)

th = 1
imask =  mask>th

canvas = np.zeros_like(img2, np.uint8)
canvas[imask] = img2[imask]

cv2.imwrite("result.png", canvas)

References
https://stackoverflow.com/questions/27035672/cv-extract-differences-between-two-images