中文说明：一种基于DCT变换的数字水印算法的实现过程，水印为伪随机序列，包括嵌入和提取两个过程。其中textmark.m为攻击实验代码。
English Description：
A digital watermarking algorithm based on DCT transform is presented. The watermark is a pseudo-random sequence, which includes two steps: embedding and extracting. TextMark. M is the attack experiment code.