public function clearExif()
    {
        $idx = 0;
        while ($idx < count($this->sections)) {
            $s = $this->sections[$idx];
            if (($s[0] == PelJpegMarker::APP1) && ($s[1] instanceof PelExif)) {
                array_splice($this->sections, $idx, 1);
                $idx--;
            } else {
                ++ $idx;
            }
        }
    }