public static function getSubPath($pFileName, $pDepth = 3)
    {
        if (empty($pFileName)) {
            return DS;
        }

        $levels = array();

        for ($i = 0; $i < $pDepth; $i++) {
            $levels[] = substr($pFileName, $i, 1);
        }

        return implode(DS, $levels) . DS;
    }