Abstract: This paper introduces an adaptive watermarking algorithm based on Arnold and the wavelet packet decomposition.The algorithm makes pretreatment of watermarking image with Arnold transform.Then the original image goes to wavelet packet decomposition.Wavelet packet decomposition can provide a more refined decomposition method，and divide the band to multi-level sub-block.Finally，the watermark image is embedded into the sub-band.Embedding strength and location are determined by the original image adaptively，it solves the contradiction between the watermark robustness and invisibility.The experimental results show that this algorithm is robust and stable to common digital image processing operations.

Key words: Arnold transform, wavelet packet decomposition, adaptive watermarking

摘要： 针对小波变换的不足，根据原始图像各子块对水印信息的适应程度不同，提出一种基于Arnold置乱和小波包分解的自适应水印算法。首先，该算法采用Arnold变换对水印图像进行预处理，然后对原始图像进行小波包分解，小波包分解能够提供一种更为精细的分解方法，将频带进行了多层次的划分，最后将水印图像嵌入到小波包分解后的子带中，水印的嵌入强度和嵌入位置均根据原始图像的内容自适应地决定，这样很好地解决了水印鲁棒性和不可见性之间的矛盾。仿真实验结果表明，算法对常见的图像攻击具有较强的鲁棒性和稳健性。

关键词: Arnold变换, 小波包分解, 自适应水印