将混合（绝对，相对）转换为绝对链接

Question

我有这个PHP脚本很好地转换几乎所有页面很好但在少数页面它无法将相对URL转换为绝对url.it给下面的链接错误的结果。

      $url = 'http://www.lowridermagazine.com/girls/1201_lrms_cat_cuesta_lowrider_girls_model/photo_01.html';

  // Example of a relative link of the page above.
  $relative = 'photo_01.html';

   // Parse the URL the crawler was sent to.
   $url = parse_url($url);

  if(FALSE === filter_var($relative, FILTER_VALIDATE_URL))
   {
    // If the link isn't a valid URL then assume it's relative and
   // construct an absolute URL.
    print $url['scheme'].'://'.$url['host'].'/'.ltrim($relative, '/');
  }

else

{
 $relative;
 }

它适用于http://www.santabanta.com/photos/shriya/9830084.htm网址但在上面的网址中失败了。 任何想法，我在做错误