Python-OpenCV cv2 OpenCV Error: Assertion failed (scn == 3 || scn == 4) in unknown function, file ..\..\..\modules\imgproc\src\color.cpp

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I am trying to learn contours in python using cv2.

I tried the following code given in a tutorial guide:

import cv2
import numpy as np
from matplotlib import pyplot as plt

im = cv2.imread('C:\Users\Prashant\Desktop\test.jpg')
imgray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(imgray,127,255,0)
image, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
img = cv2.drawContour(im, contours, -1, (0,255,0), 3)
cv2.imshow('Image1',img)

I am getting this error:

File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 540, in runfile
OpenCV Error: Assertion failed (scn == 3 || scn == 4) in unknown function, file ..\..\..\modules\imgproc\src\color.cpp, line 3402
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
   execfile(filename, namespace)
 File "C:/Users/Prashant/.spyder2/.temp.py", line 15, in <module>
   imgray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
 cv2.error: ..\..\..\modules\imgproc\src\color.cpp:3402: error: (-215) scn == 3 || scn == 4
python-2.7 opencv image-processing numpy
4 Answers

1st print ret. If it is showing false then your image is not taken properly. If it is showing True Try this command - sudo modprobe bcm2835-v4l2 Or in your /etc/modules file add bcm2835-v4l2 at the bottom.

user_80115960

I had this problem and couldn't find a solution, but on the web, it was working. My solution was almost funny - you can't have two streams. I turned off the web stream and then it was fine!

user_111144440
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