Abstract: This paper proposes a new type of multi-user digital watermarking based on CDMA, which aims at the demand of multi-user copyright sharing protection. It presents two CDMA based approaches, i.e. wavelet domain direct approach (WD) and wavelet domain neighbor linear prediction approach (WNLP). It analyses the influence of user number and embedding depth on the quality of watermarked images and extracted watermarks. Experiment results show that the algorithm can solve the problems of watermarking collision and relieve the restriction of user number in multiple watermarking algorithms.

Key words: multiple watermarking, CDMA, copyright sharing protection

摘要： 针对多用户共享版权时联合水印嵌入等需求，提出了基于CDMA的多用户多重数字水印算法。提出并实现了小波域直接嵌入（WD）和基于邻域线性预测值嵌入（WNLP）两种CDMA水印方案。分析了用户数量和嵌入深度对含印图像质量和提取水印质量的影响。实验结果表明，该算法能有效解决多重数字水印中水印碰撞和用户数量受限问题。

关键词: 多重数字水印, CDMA, 共享版权保护