说明：  信息隐藏与水印技术系列实验之五：Watermark_1,Watermark_2,Watermark_3,Watermark_4的实验指导书。通过这四个算法的熟悉后，只需修改嵌入、提取、攻击函数源码，即可快速实现各种图像水印算法。
(Information Hiding and Watermarking five series of experiments: Watermark_1, Watermark_2, Watermark_3, Watermark_4 Experimental instructions. Through these four algorithms are familiar with, simply amend the embedding, extraction, attack source function, you can quickly achieve a variety of image watermarking algorithm.)