public function getInvertedColor($color)
    {
        $color = str_replace('#', '', $this->hex6($color));

        if (strlen($color) != 6) {
            return '#000000';
        }

        $rgb = '';
        for ($x = 0; $x < 3; $x++) {
            $c = 255 - hexdec(substr($color, (2 * $x), 2));
            $c = ($c < 0) ? 0 : dechex($c);
            $rgb .= (strlen($c) < 2) ? '0'.$c : $c;
        }
        return '#'.$rgb;
    }