title: OpenCV - How to extract edges form result of Canny Function?
body: <p>I'm using Canny() Function in OpenCV as below</p>
  
  <pre><code>Mat detected_edges = GetImage...;
  Canny( detected_edges, detected_edges, 20, 20*3, kernel_size );
  </code></pre>
  
  <p>My problem is the result of this function only a black-white image, I want to get the set of edges that detected.</p>
  
  <p>On OpenCV docs wrote </p>
  
  <blockquote>
    <p>The function finds edges in the input image image and marks them in
    the output map edges using the Canny algorithm.  The smallest value
    between threshold1 and threshold2 is used for edge linking.  The
    largest value is used to find initial segments of strong edges.</p>
  </blockquote>
  
  <p>But I don't know how to extract lines from the result image, someone can help me.</p>
  
  <p><strong>UPDATE</strong> The image that I used to test below, this image include the result of Canny function</p>
  
  <p><img src="https://i.stack.imgur.com/bIm2g.png" alt="enter image description here"></p>