title: Add copies of a dimension in Python - numpy.ndarray
body: <p>I have an image (numpy.ndarray) shaped like this:</p>
  
  <pre><code>In : print(img.shape)
  Out : (240, 320, 1)
  
  In : print(img) # The output it's simplified
  Out:[[[121]
        [119]
        [118]
        ..., 
        [ 39]
        [ 43]
        [ 44]]
  </code></pre>
  
  <p>And I need to add copies to look like this:</p>
  
  <pre><code>shape (240, 320, 3) 
      [[[121   121   121]
        [119   119   119]
        [118   118   118]
        ..., 
        [ 39   39   39]
        [ 43   43   43]
        [ 44   44   44]]
  </code></pre>
  
  <p>Any tips on how to achieve that?</p>