public function getExif()
    {
        $sections_count = count($this->sections);
        for ($i = 0; $i < $sections_count; $i ++) {
            $section = $this->getSection(PelJpegMarker::APP1, $i);
            if ($section instanceof PelExif) {
                return $section;
            }
        }
        return null;
    }