title: Having a hard time finding any tutorials/examples for the FREAK feature extractor
body: <p>I am trying to implement a feature/object tracking application using OpenCV and C++.  Currently I am using the <code>goodFeaturesToTrack</code> function to create my feature vector from my first frame. From there, I am passing it to the <code>calcOpticalFlowPyrLk</code> method to track the points through subsequent frames.</p>
  
  <p>This method is quite fast, but unstable and not scale or rotation invariant. Features have the tendency to drift together as well as get lost and lock onto another corner in the scene. I have been reading a lot about FREAK and it seems like an attractive option. Hopefully it will fix my stability problem as well as being scale and rotation invariant. </p>
  
  <p>While trying to find some help on implementing the FREAK feature extractor, I came across <a href="https://stackoverflow.com/questions/12900514/opencv-2-42-featuredetector-freak/13835199#13835199">this</a> which got my hopes up, but as you have probably noticed, the file is offline! I was just curious if anyone may have saved the example or have any suggestions as to where I can look for some alternative source code I can study and learn from?</p>