// datas
  $search = array('%id%', '%filename%', '%author%', '%dimensions%', '%description%');
  $replace = array($row['id'], $row['filename']);

  $replace[2] = empty($row['author']) ? null : $row['author'];
  $replace[3] = empty($filesize) ? null : $filesize['width'].'x'.$filesize['height'];

  $filename = str_replace($search, $replace, $file_pattern);