一种基于复合混沌序列的扩频水印算法*

提出了一种安全性高的DWT（discrete wavelet transform）域鲁棒性扩频水印算法。该算法用Arnold变换对水印置乱，而后基于复合混沌二值序列对水印图案信号进行加密和扩频，并给出了一种小波域中量化步长的自适应确定方法，通过奇偶量化的方法将二值水印比特批量嵌入到载体的频域系数中。复合混沌密钥的使用与小波域系数修改的隐蔽性，增强了水印算法的安全性，基于混沌序列扩频码的扩频水印技术增强了水印的鲁棒性，同时很好地兼顾了水印的不可见性，并且实现了水印信息的盲提取。

Spread spectrum watermarking algorithm based on compound chaotic sequence

This paper put forward a robust spread spectrum algorithm with high safety in DWT(discrete wavelet transform)domain.Permuted watermark by Arnold transformation,then encrypted and spread based on compound chaotic binary sequence.And presented a method of fixing quantization step adaptively in DWT domain.Embedded binary watermark bits in frequency domain through odd-even quantization.The use of compound chaotic keys and privacy of modification on coefficients of DWT domain enhanced the security of watermarkin...