title: Apache rewrite to other directory, if file exists there
body: <p>My directories look like this:</p>
  
  <pre><code>/assets
    /images
      /2011
      /2012
    /images-hq
      /2011
      /2012
  </code></pre>
  
  <p>In the html file every image has a tag like:  </p>
  
  <pre><code>&lt;img src="/assets/images/2012/example.jpg" /&gt;
  </code></pre>
  
  <p>I want to check, if the same image exists in the images-hq folder, and if it is there, i want to send that image to the user.</p>
  
  <p>Example:</p>
  
  <pre><code>/assets/images/2012/example.jpg to /assets/images-hq/2012/example.jpg
  </code></pre>
  
  <p><strong>IF</strong> /assets/images-hq/2012/example.jpg exists, if not, just serve the original.</p>