add_event_handler('loc_end_index_thumbnails', 'add_thumbnails_high_url', 50, 2);

function add_thumbnails_high_url($tpl_var, $pictures)
{
  include_once(PHPWG_ROOT_PATH.'include/functions_picture.inc.php);

  foreach($tpl_var as $key => $value)
  {
    if ($value['FILE_HAS_HD'])
    {
      $tpl_var[$key]['HD_PATH'] = get_high_path($pictures[$key]);
    }
  }

  return $tpl_var;
}