builtins.ValueError: not enough values to unpack (expected 3, got 2)
旧版OpenCV:返回三个参数
image, contours, hierarchy = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
新版OpenCV:返回两个参数
contours,hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)