title: SURF + LSH - OpenCV - Detecting same page scan
body: <p>I'm using OpenCV and I'm trying to recognize when a scan of a page of a book is already taken or not. I already looked at <a href="https://stackoverflow.com/questions/2146542/opencv-surf-how-to-generate-a-image-hash-fingerprint-signature-out-of-the-d">this post</a> but didn't help me enough.</p>
  
  <p>Currently I'm computing a 1:N SURF matching between the input image and all the other pages I scanned so far.</p>
  
  <p>This method works pretty good, also by just taking a 192x192 square containing text, not the whole image, it's able to distinguish them.</p>
  
  <p>I'd like to know if you think there is a faster method than this one, I thought about <a href="http://en.wikipedia.org/wiki/Locality_sensitive_hashing" rel="nofollow noreferrer">LSH</a> so that I would have just to extract the features from the input image, hash the features in some way and then check if I reached a bucket already used or not.</p>
  
  <p>So basically my question is, do you think that the method I described above could work? And if yes, how to do the hash function?</p>
  
  <p>Thanks,
  .A</p>