protected function getConfiguredFormat()
    {
        $format = $this->config->get('concrete.misc.default_thumbnail_format');
        if ($format === static::FORMAT_AUTO || $this->bitmapFormat->isFormatValid($format)) {
            $result = $format;
        } elseif ($format === 'jpg') { // legacy value
            $result = BitmapFormat::FORMAT_JPEG;
        } else {
            $result = static::FORMAT_AUTO;
        }

        return $result;
    }