title: How to calculate detection_score for OpenCV's face detector?
body: <p>I want to use <a href="http://vis-www.cs.umass.edu/fddb/" rel="nofollow">FDDB</a> to evaluate some face detectors including OpenCV. But FDDB's detection output file requires:</p>
  
  <pre><code>&lt;left_x top_y width height detection_score&gt;
  </code></pre>
  
  <p>It include a <code>detection_score</code> part. But the opencv's detector have no output like this. How to output this?</p>