基于Gold码的扩频数字水印算法

Spread Spectrum Digital Watermarking Algorithm Using Gold Codes

提出了一种将Gold码用于水印结构设计的扩频数字图像水印算法.利用Gold码具有较多独立码的特性,以多位二进制信息为单位对二值图像水印进行扩频调制,然后将调制信号自适应地加入到载体图像离散余弦变换域的低频分量系数中.Gold码的应用使得算法可以采用较长的扩频序列,从而提高鲁棒性.为了进一步减小算法对载体图像大小的要求,利用Gold码间的近似正交性,在该算法中应用了码分多址技术来压缩扩频后水印信息的数据量.实验表明,相对于使用m序列或正交序列对作扩频序列的算法,该算法对于抵抗各种噪声、滤波和压缩等攻击具有更好的鲁棒性.

A spread spectrum digital image watermarking algorithm was proposed, in which Gold codes were applied to the structure design of watermark. By exploiting the characteristics that Gold codes have more independent codes, the binary image watermark was modulated with multi-bit binary information regarded as an unit, and then adaptively embedded into low frequency components of the original image in discrete cosine transform domain. Thus, the longer spread spectrum sequences could be used and the robustness enhanced by utilizing the Gold codes. To reduce the size requirements of the original image, the approximate orthogonality between the Gold codes was considered and the code division multiple access technique was used to compress the data of the modulated watermark signal in the proposed algorithm. Experimental results show that this scheme, compared with algorithms that use m-sequence or orthogonal sequence-pair, is more robust against the typical image processing attacks such as adding noise, filtering and lossy compression.