public function getRgbHexString()
    {
        $red = dechex($this->getRed());
        if (strlen($red) === 1) {
            $red = '0'.$red;
        }
        $green = dechex($this->getGreen());
        if (strlen($green) === 1) {
            $green = '0'.$green;
        }
        $blue = dechex($this->getBlue());
        if (strlen($blue) === 1) {
            $blue = '0'.$blue;
        }

        return $red.$green.$blue;
    }