I'm following a simple tutorial example. But this call to drawContours is returning None.
contours,hierarchy = cv2.findContours(th3,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
img2 = cv2.drawContours(img, contours, -1, (0,255,0), 3)
I'm not getting an error. The contours and hierarchy arrays look plausibly full of points. (th3 is a thresholded version of img) But img2 is None
Anyone got any ideas?
(BTW : I'm using opencv 2.4.9.1)