这是基于离散余弦DCT的数字水印算法的实现，图片自由选择，可以对嵌入水印的图像进行各种攻击后提取水印。鲁棒性较强。-This is the realization of digital watermarking algorithm based on discrete cosine of DCT, picture free choice, can of the embedded watermark image of various attacks watermark extraction. Str