title: Understanding histogram() in Pillow
body: <p>From the docs:</p>
  
  <blockquote>
    <p>im.histogram() => list<p>
    Returns a histogram for the image. The histogram is returned as a list
    of pixel counts, one for each pixel value in the source image. If the
    image has more than one band, the histograms for all bands are
    concatenated (for example, the histogram for an “RGB” image contains
    768 values).</p>
  </blockquote>
  
  <p>I understand that there are 256 values for Red, 256 for Green and 256 for Blue (256 * 3 = 768).</p>
  
  <pre><code>for i, value in enumerate(im.histogram()):
      print i, value
  </code></pre>
  
  <p>Produces:</p>
  
  <pre><code>0 329
  1 145
  ... (skipping some)
  256 460
  ... (skipping some)
  767 3953
  </code></pre>
  
  <p><strong>My question is:</strong> does that mean that there were:<br>
  329 pixels that had a value of <code>R = 0, G = 0, B = 0</code> and <br>
  145 pixels that had a value of <code>R = 1, G = 0, B = 0</code> and <br>
  460 pixels that had a value of <code>R = 256, G = 1, B = 0</code> and <br>
  3953 pixels that had a value of <code>R = 256, G = 256, B = 256</code> etc. ? <p>Is that how I should read the output?</p>