canvas 隐写术
http://www.alloyteam.com/2016/03/image-steganography/#prettyPhoto
https://www.cnblogs.com/Miracle-ZLZ/p/14137350.html
http://www.alloyteam.com/2016/03/image-steganography/#prettyPhoto
https://www.cnblogs.com/Miracle-ZLZ/p/14137350.html