title: Orientational Canny Edge Detection
body: <p>I want to detect edges using Canny method. In the end I want two edge maps: 1 for horizontal 1 for vertical direction. </p>
  
  <p>In MATLAB this can be achieved by using Sobel or Prewitt operators with an extra direction argument, but for Canny we do not have this option.</p>
  
  <pre><code>E = edge(I,'Sobel','horizontal')
  </code></pre>
  
  <p>Any idea how to extract both horizontal and vertical edges, separately, by using Canny?</p>