CRC校验中叠加和校验方法的生成，校验等功能函数源码。

一种实现叠像术的代码,可以将一张图片的信息分散到三张图片中,三张图片通过叠加算法可以恢复原图信息-Stack as a technique to achieve the code, can be a picture of the information distributed among the three images, three images through the image stack algorithm can recover information