title: gravatar highest resolution
body: <p>I show a gravatr image of users in my site. How can I know the best highest resolution to use? e.g. which parameter "s" should be. </p>
  
  <pre><code>https://secure.gravatar.com/avatar/?s=250
  </code></pre>
  
  <p>of course it depends in the user image, but gravatr must know the resolution of the initial image and can advise me on best highest size.</p>