title: Convert image to a digital matrix using python
body: <p>I have an image "felix.png" (280x280). </p>
  
  <p>and I'm converting this image to digital matrix:</p>
  
  <pre><code>from PIL import Image
  from numpy import array
  
  
  
  
  img = Image.open('felix.png')
  arr = array(img)
  </code></pre>
  
  <p>the shape of this array is (280,280,3) and I wonder why each pixel is represented with 3 dimensional array?  </p>
  
  <p>for example <code>arr[0][0]</code> is <code>[255,255,255]</code>...</p>