Related: Easy install: OpenCV 3 for Python
Some legacy modules like Horn Schunck Optical Flow in OpenCV 2.4 are located in
cv instead of
Note: legacy modules are no longer available in OpenCV 3.
Windows-based OpenCV 2.4 requires importing legacy functions as below, which is also Mac/Linux compatible:
import cv2 from cv2 import cv
Instead of using OpenCV 2.4, use pure Python for Horn Schunck and Lucas Kanade Optical Flow.