title: OpenCV-Python: img is not a numpy array, neither a scalar
body: <p>I'm trying to write a save image function. The below code is expected to create a copy of the original image as saved-test-image.jpg.</p>
  
  <pre><code>originalImage = "test-image.jpg"
  savedImage = cv2.imwrite("saved-test-image.jpg",originalImage)
  </code></pre>
  
  <p>The execution of the lines gives the follwing back:</p>
  
  <pre><code>Traceback (most recent call last):
    File "UnitTest.py", line 159, in test_save_and_delete_image
      savedImage = cv2.imwrite('unittest-images/saved-test-image.jpg', originalImage)
  TypeError: img is not a numpy array, neither a scalar
  </code></pre>
  
  <p>What needs to be changed here? </p>