title: Merging ndarray image
body: <p>I have an image as an <code>ndarray</code> with a shape of <code>(2000, 2000, 3)</code>. In a next step a split the channels to do some work on them:</p>
  
  <pre><code>image_r = (image_color[:,:,0])
  image_g = (image_color[:,:,1])
  image_b = (image_color[:,:,2])
  </code></pre>
  
  <p>When the work is done I need to merge the channels to one image. How do I do that?</p>
  
  <p>I tried to generate an empty image <code>full_image = np.zeros((image.shape[0], image.shape[1]), 3)</code> And to append the channels to it. But this didn't work out. </p>
  
  <p>I also tried to stack the values using the hstack.</p>
  
  <pre><code>full_image = np.zeros((image.shape[0], image.shape[1]))
  full_image = np.hstack(full_image, image_r)
  full_image = np.hstack(full_image, image_g)
  full_image = np.hstack(full_image, image_b)
  </code></pre>
  
  <p>But this didn't work out either. With the following error:   </p>
  
  <pre><code>full_image = np.hstack(full_image, image_r)
    File "&lt;__array_function__ internals&gt;", line 4, in hstack
  TypeError: _vhstack_dispatcher() takes 1 positional argument but 2 were given
  </code></pre>
  
  <p>Do you have any ideas?</p>