title: Python add one more channel to image
body: <p>I'm trying to add channel because of below error </p>
  
  <blockquote>
    <p>ValueError: could not broadcast input array from shape (48,48) into shape (48,48,1)</p>
  </blockquote>
  
  <p>Code:</p>
  
  <pre><code>img = cv2.imread(f,0)
  resized = cv2.resize(img, (48,48), interpolation = cv2.INTER_AREA)
  print(resized.shape) 
  (48, 48)
  </code></pre>
  
  <p>But I need a channel image like (48,48,1).</p>
  
  <p>How can I solve this?</p>