title: Can't modify numpy array
body: <p>I got stuck practising with images in Python 3:</p>
  
  <pre><code>import numpy as np
  from matplotlib.image import imread
  photo_data = imread('c:\jpeg.jpg')
  photo_data[0,0,1] = 0
  </code></pre>
  
  <p>I get this error</p>
  
  <pre><code>---------------------------------------------------------------------------
  ValueError                                Traceback (most recent call last)
  &lt;ipython-input-40-f19579124b68&gt; in &lt;module&gt;()
        1 photo = photo_data
        2 print(type(photo))
  ----&gt; 3 photo[0,0,1] = 0
        4 plt.imshow(photo_data)
  
  ValueError: assignment destination is read-only
  </code></pre>
  
  <p>I'm following an online course where this code seems working, can you tell me what I'm getting wrong?</p>