title: module 'cv2.cv2' has no attribute 'COLOR_BGR2GREY'
body: <p>I am getting the following error when running my script:</p>
  
  <pre><code>Traceback (most recent call last):
  File "C:/PyCharm/SDC_1/Lane_Finding.py", line 3, in &lt;module&gt;
  grey = cv.cvtColor(image, cv.COLOR_BGR2GREY)
  AttributeError: module 'cv2.cv2' has no attribute 'COLOR_BGR2GREY'
  </code></pre>
  
  <p>The script: </p>
  
  <pre><code>1: import cv2 as cv 
  
  2: image = cv.imread('solidWhiteRight.jpg')
  
  3: grey = cv.cvtColor(image, cv.COLOR_BGR2GREY)
  </code></pre>
  
  <p>I only have the "opencv-contrib-python" package currently installed in my virtual environment as I saw this was an issue with similar problems. Do I need to install another package along with that? I am able to print the image variable and I get a matrix of values. </p>
  
  <p>Any help on this would be greatly appreciated, and thanks in advance!</p>
  
  <p>UPDATE:</p>
  
  <p>When I write and save the image, the image comes back as a greyscale image. However when I display it using matplotlib.pylot, it converts the image to a multi colored image. Does anyone know why this would be?</p>
  
  <p>Code:</p>
  
  <pre><code>import cv2 as cv
  import matplotlib.pyplot as plt
  path = 'solidWhiteRight.jpg'
  image = cv.imread(path)
  gray = cv.cvtColor(image, cv.COLOR_BGR2GRAY)
  cv.imwrite('grey_image.jpg', gray)
  plt.imshow(gray)
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/A6Km1.png" rel="nofollow noreferrer">Result of plt.show:</a></p>