OpenCV Contours - need more than 2 values to unpack

Question

I am trying to implement contours using the following code..

im = cv2.imread(\'C:\\Users\\Prashant\\Desktop\\T.jpg\')
imgray = cv2.cvtColor(im,cv2.COLOR_BGR2         


        

Answer 1

Python version 2.7.14 (v2.7.14:84471935ed, Sep 16 2017, 20:25:58) [MSC v.1500 64 bit (AMD64)]

NumPy version: 1.16.1

argparse version: 1.1

CV2 version: 4.0.0

Traceback (most recent call last):

  File "omr.py", line 254, in 

    main()

  File "omr.py", line 237, in main

    answers, im = get_answers(args.input)

  File "omr.py", line 188, in get_answers

    contours = get_contours(im)

  File "omr.py", line 26, in get_contours

    im2, contours, hierarchy =cv2.findContours(image_gray,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

ValueError: need more than 2 values to unpack

This is resolved by removing 'im2 ,' from line 26.. as in OpenCv version 3.0 or higher, the function 'findContours' returns only 2 values.. so the statement should be

contours, hierarchy =cv2.findContours(image_gray,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

and also upgrade your OpenCv version