结合置乱与扩频的数字水印算法

提出了一种使用置乱技术置乱水印图像，然后将Gold码用于水印结构设计的扩频数字水印算法。通过置乱技术提高了抽取数字水印的视觉效果，并可以在一定程度上弥补数字水印在嵌入、传输和抽取过程中的损耗。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置乱后的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。应用Gold码使得算法可以采用较长的扩频序列，相应提高了鲁棒性。这种结合置乱和扩频的水印算法对于抵抗各种噪声、滤波和压缩等合法攻击以及其他非法攻击都具有很好的鲁棒性。

Digital watermarking algorithm combining spread spectrum with image scrambling

A spread spectrum digital image watermarking algorithm was proposed,in which Gold codes were applied to the structure design of watermark and image scrambling was used to scramble watermarking image.Image scrambling improved vision effect of watermarking image.By exploiting the characteristics that Gold codes have more independent codes,the binary image watermark was modulated with multibit binary information regarded as an unit,and then was adaptively embedded into low frequency components of the scrambling image in discrete cosine transform domain.The longer spread spectrum sequences could be used and the robustness accordingly is enhanced by utilizing the Gold codes.This scheme combining spread spectrum with(image) scrambling is more robust against various attacks,such as adding noise,filtering and lossy compression.