基于布谷鸟搜索算法的小波域数字水印方法

Cuckoo-search-algorithm-based Watermarking Method in Wavelet Domain

为更好地平衡数字水印的鲁棒性和透明性,提出一种基于布谷鸟搜索算法的小波域数字水印方法.该方法首先将原始载体图像进行3级Harr小波变换,选择第3级水平细节子图作为水印嵌入位置,同时将水印经Arnold变换和一维化后作为待嵌入水印信息;然后借鉴布谷鸟搜索算法确定最优的水印嵌入系数嵌入水印.布谷鸟搜索算法的目标函数综合考虑了水印的鲁棒性和透明性,鲁棒性指标考虑了压缩、缩放、剪切、滤波以及噪声干扰等多种攻击的影响,而透明性指标则取决于载体图像在水印嵌入前后的小波系数变化.实验结果表明,与现有的一些基于群智能算法的水印方法相比,本文方法既能保证较好的水印透明性,又具有更强的抗攻击能力.

To obtain a better balance of robustness and imperceptibility in digital watermarking, this paper proposes a novel water- marking method in wavelet domain which employs the Cuckoo Search Algorithm. In this method, the third-level horizontal detail sub- image obtained by applying 3-Level Wavelet Transform to the cover image is selected as the embedded position, and the watermark is scrambled with Arnold Transform and changed into a one-dimensional bit stream. Then the Cuckoo Search Algorithm is employed to determine the best embedding coefficient. Both the robustness and imperceptibility are taken into account in designing the objection function of the Cuckoo Search Algorithm, where the former makes a full consideration of the attacks such as compressing, scaling, cutting, filtering, and noise disturbance, and the latter is designed according to the wavelet coefficients of the cover images before and after embedding the watermark. Experimental results show that compared with some existing methods based on swarm intelligence, this method has stronger robustness for anti-attack while preserving the imperceptibility.