private function getText($image)
    {
        $rtn = '';
        $w = imagesx($image);
        $h = imagesy($image);
        for ($y = 0; $y < $h; ++$y) {
            for ($x = 0; $x < $w; ++$x) {
                $rgb = imagecolorat($image, $x, $y);
                $rtn .= $this->getDotFromRgb($rgb);
            }
        }

        return $rtn;
    }