一种基于DWT和DCT的数字图像水印算法

A digital image watermarking algorithm based on DWT and DCT

提出了一种基于DWT与DCT变换的数字图像水印算法。算法首先对载体图像进行DWT,然后根据DWT低频子图的纹理特性,将DWT低频子图进行分块,再对分块子图进行DCT,选择每块DCT系数的直流分量嵌入水印,并纹理特性嵌入不同强度水印信息。为提高水印的安全性,算法首先对原始二值水印图像进行logistic混沌调制后再进行Arnold置乱。实验结果证明,该算法能有效地抵抗噪声、JPEG压缩、滤波、剪切等攻击。

A digital image watermarking algorithm based on the combination of DWT and DCT is proposed. The low frequency sub image of discrete wavelet transform of original cover image is extracted and than divided into 8＊8 blocks. After the discrete cosine transform of the blocks, the watermark information is embedded into DC component with different strength according to the classification based on the characteristic sub image texture. Experimental results show that the algorithm has a good robustness against noise,JPEG compression, filtering and cropping attacks. To improve the security of watermark,the original watermark is modulated by logistic chaotic sequence and Arnold scrambling.