title: Python PIL combine images results in an all black image
body: <p>I am trying to use the following to combine three images into one using PIL and Python</p>
  
  <pre><code>import sys
  from PIL import Image
  
  images = map(Image.open, ['ib1.jpg', 'ib2.jpg', 'ib3.jpg'])
  widths, heights = zip(*(i.size for i in images))
  
  total_width = sum(widths)
  max_height = max(heights)
  
  new_im = Image.new('RGB', (total_width, max_height))
  
  x_offset = 0
  for im in images:
    new_im.paste(im, (x_offset,0))
    x_offset += im.size[0]
  
  new_im.save('test.jpg')
  </code></pre>
  
  <p>The test.jpg image seems to be the correct height but the image is totally black.</p>
  
  <p>Can anyone help?</p>