title: Unsupported depth of input image: 'VDepth::contains(depth)' where 'depth' is 4 (CV_32S)
body: <p>I'm trying to process some images in OpenCV. Specifically, swapping color panes using the following functions. </p>
  
  <pre><code>def green_ble_swap(image)
      im_rgb = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
      im_copy = np.copy(im_rgb)
      blue = im_copy[:,:,2].copy()
      green = im_copy[:,:,1].copy()
      im_copy[:,:,2] = green
      im_copy[:,:,1] = blue
      return im_copy
  </code></pre>
  
  <p>However I get the following error. </p>
  
  <pre><code>&gt; Unsupported depth of input image:
  &gt;     'VDepth::contains(depth)'
  &gt; where
  &gt;     'depth' is 4 (CV_32S)
  </code></pre>
  
  <p>Not sure whats the error here. </p>