$name = './' . $tileset . '/' . $z . '/' . $x . '/' . $y;
      $mime = 'image/';
      if($ext != null){
        $name .= '.' . $ext;
      }
      if ($fp = @fopen($name, 'rb')) {
        if($ext != null){
          $mime .= $ext;
        }else{
          //detect image type from file
          $mimetypes = ['gif', 'jpeg', 'png'];
          $mime .= $mimetypes[exif_imagetype($name) - 1];
        }
        header('Access-Control-Allow-Origin: *');
        header('Content-Type: ' . $mime);
        header('Content-Length: ' . filesize($name));
        fpassthru($fp);
        die;