title: Why does scipy.ndimage.io.imread return PngImageFile, not an array of values
body: <p>I have two different machines with scipy 0.12 and PIL installed. On one machine, when I try to read a .png file, it returns an array of integers with size (w x h x 3):</p>
  
  <pre><code>In[2]:  from scipy.ndimage.io import imread
  In[3]:  out = imread(png_file)
  In[4]:  out.shape
  Out[4]: (750, 1000, 4)
  </code></pre>
  
  <p>On the other machine, using the same image file, this returns a <code>PIL.PngImagePlugin.PngImageFile</code> object wrapped in an array</p>
  
  <pre><code>In[2]: from scipy.ndimage.io import imread
  In[3]: out = imread(png_file)
  In[4]: out.shape
  Out[4]: ()
  In[5]:  out
  Out[5]: array(&lt;PIL.PngImagePlugin.PngImageFile image mode=RGBA size=1000x750 at 0x1D40050&gt;, dtype=object)
  </code></pre>
  
  <p>I can't see any way to access the data for the latter object.</p>
  
  <p>I have the vague sense that something is wrong with the way PIL is using Png libraries to read the image, but is there something more specific that would be wrong and cause this behavior?</p>