实现直接序列扩频水印的嵌入与提取。基于待嵌入消息生成二进制水印序列,生成扩频码，用消息序列调制生成水印序列。依次处理灰度图像的每一个载体图像像素，根据相应位置 水印序列完成嵌入修改。(Realize the embedding and extraction of direct sequence spread spectrum watermark. The binary watermark sequence is generated based on the message to be embed