title: How to get rgb value by cimg?
body: <pre><code>CImg&lt;unsigned char&gt; src("image.jpg");
  int width = src.width();
  int height = src.height();
  unsigned char* ptr = src.data(10,10); 
  </code></pre>
  
  <p>How can I get <code>rgb</code> from <code>ptr</code>?</p>