public function parse(array $tag, $content) {

        // If more than 1 http:// is found in the string, possible XSS attack
        if ((mb_substr_count($content, 'http://') + mb_substr_count($content, 'https://')) > 1) {
            return null;
        }

        $tag['attributes']['src'] = $content;

        if (!empty($tag['attributes']['default'])) {
            list($width, $height) = explode('x', $tag['attributes']['default']);

            $tag['attributes']['width'] = $width;
            $tag['attributes']['height'] = $height;
        }

        if (empty($tag['attributes']['alt'])) {
            $tag['attributes']['alt'] = '';
        }

        return parent::parse($tag, $content);
    }