title: Using mod_rewrite to call in a default image URL if requested image URL is not found
body: <p>I'm fairly new to htaccess rewrites and wondered if anyone could offer a solution for me. So on my site I have users with custom avatar images in the following format.</p>
  
  <p><a href="http://siteurl.tld/customavatars/avatar78364_1.gif" rel="nofollow noreferrer">http://siteurl.tld/customavatars/avatar78364_1.gif</a>
  (Where the numbers (78364_1) are the users ID)</p>
  
  <p>Each user gets their own customavatars image link generated even if they dont have an image uploaded. Here is the issue, at the moment I'm using an ErrorDocument 404 /images/icons/no-avatar.png as a default image for any users without their own image uploaded. This 404 isn't good for SEO so what I want to try do is use rewrites to keep the origin URL but serv the no-avatar image file.</p>
  
  <p>In effect anyone going to <a href="http://siteurl.tld/customavatars/avatarUSERID_HASNOIMAGE.gif" rel="nofollow noreferrer">http://siteurl.tld/customavatars/avatarUSERID_HASNOIMAGE.gif</a> is just shown the default image without being redirected to no-avatar.png in the browser URL.</p>