title: OpenCV - Read a gray scale or monochrome image with alpha channel
body: <p><strong>UPDATE 2018-10-13</strong></p>
  
  <p>This issue has been fixed in OpenCV 3.4</p>
  
  <pre><code>import cv2
  import numpy as np
  image = cv2.imread('1.png', cv2.IMREAD_UNCHANGED)
  
  image.shape
  &gt;&gt; (480, 960, 4)
  
  np.sum(img[:,:,:3])
  &gt;&gt; 0
  
  np.mean(img[:,:,3])
  &gt;&gt; 37.929637586805555
  </code></pre>
  
  <hr>
  
  <p>A similar question has been asked but unanswered <a href="https://stackoverflow.com/questions/39268301/opencv-load-image-with-alpha-channel-but-8bit-depth">here</a>.</p>
  
  <p>How can I read a gray scale image in OpenCV with alpha channel? For example, if I try to read the following image, all I get is 2d array of all zeros.</p>
  
  <p><a href="https://i.stack.imgur.com/Us9Yz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Us9Yz.png" alt="enter image description here"></a></p>
  
  <pre><code>image = cv2.imread('1.png', cv2.IMREAD_UNCHANGED)
  image.shape
  
  (480, 960)
  </code></pre>