title: Finding center of fingerprints
body: <p>If we suppose that every fingerprint is made of concentric curves (ellipses or circles) - and I'm aware of the fact that not <strong>every</strong> fingerprint is - how can I <strong>find center of those concentric curves?</strong></p>
  
  <p>Let's take this "ideal" fingerprint and try to find out its center ...</p>
  
  <p><img src="https://i.stack.imgur.com/i55gy.png" alt="alt text"></p>
  
  <p>My approaches were to try:</p>
  
  <ul>
  <li>Find the spectrum through columns/rows of the image and try to find columns/rows that maximize particular band of the spectrum. I thought that column going through the center would have most regular pattern of changing amplitudes - therefore, most recognizible harmonic.</li>
  <li>My second approach was to try to count the changes of black-and-white also through the columns and rows, and to maximize that amount among rows and columns also.</li>
  </ul>
  
  <p>While these methods work to the some extant, with some additional filtering, they fail, when fingerprint is "not ideal as this one is". Can you think of any different approach? Are there standard ways to do it?</p>
  
  <p><strong>Edit 1</strong> I really like Zack's idea now, and would like for someone to make it a bit more clear how to do it...</p>
  
  <p><strong>Edit 2</strong> I wished someone had expounded on Zack's idea a bit more. Bounty given to Zack.</p>
  
  <p><strong>Edit 3</strong> Fingerprint with center of curves that approximate ridges outside of fingerprint.
  <img src="https://i.stack.imgur.com/s3YT6.png" alt="alt text"></p>