https://blog.wongcw.com/2018/11/28/aoaophoto-watermark-v8-7%e8%a8%bb%e5%86%8a%e7%89%88-key%e5%9c%96%e5%83%8f%e6%b0%b4%e5%8d%b0%e5%b7%a5%e5%85%b7/