php中file_get_contents的图片乱码

        // https://packagist.org/packages/endroid/qr-code#2.x-dev

        $qrCode = new QrCode('http://www.baidu.com');

        $qrCode->setSize(100);

        $qrCode->setEncoding('UTF-8');

        header('Content-Type: ' . $qrCode->getContentType());

        echo $qrCode->writeString();

        die; #不能少否则乱码