基于小波基的CDMA自适应水印算法

提出一种以正交小波基作为扩频码的CDMA自适应水印算法。该方法通过对Haar小波基进行平移和尺度伸缩，离散化为一组多值正交码序列，用它作为CDMA扩频码，将二值水印图像扩频后，自适应嵌入在宿主图像的第三级细节子图上。理论分析与仿真结果表明，该方法可有效提高隐藏信息的容量和安全性。通过与哈达玛序列和改进gold码的仿真比较，证明多值序列作为扩频码CDMA水印的抗攻击能力优于二值序列。

CDMA Adaptive Watermarking Algorithm Based on Wavelet Basis

A new digital CDMA watermarking algorithm based on orthogonal wavelet basis is proposed in this paper. Harr wavelet basis is changed into a multilevel orthogonal sequence by scaling and translation, which is used to encode the binary image. Then the CDMA encoded watermark is adaptively embedded into the third level detail sub-images of DWT domain. Theoretical analysis and experimental results show that the capacity of the hidden information is raised and the security is enhanced. Compared with Hadamard sequence and improved gold sequence in the simulation, the multilevel sequence performs better than binary sequence in attack-resistance.