基于NSCT和DFRFT的数字水印算法研究

为了有效地克服外界攻击对数字水印的破坏性,增强数字水印的鲁棒性,提出了一种基于非下采样轮廓波变换(Nonsample Contourlet Transform,NSCT)与离散分数阶傅里叶变换(Discrete Fractional Fourier Transform,DFRFT)相结合的数字水印算法.首先,通过Logistic置乱处理水印信号,增强水印的安全性;然后,对宿主图像进行NSCT分解,对其中的低频分量进行DFRFT分解;最后,将置乱的水印图像嵌入到DFRFT分解系数中,从而进一步加强水印的不可见性和鲁棒性.实验结果表明,该算法不仅具有较好的鲁棒性,还可以有效地抵抗外界攻击.

A Digital Watermarking Algorithm Based on NSCT and DFRFT

In order to overcome the external destructive attacks on digital watermarking effectively and enhance the robustness of digital watermarking, a digital watermarking algorithm based on Nonsample contourlet transform (NSCT) and Discrete fractional Fourier transform (DFRFT) is proposed in this paper. The watermark image is processed by Logistic scrambling to enhance the security of the digital watermarking. Then the low-frequency sub-band which is calculated by NSCT decomposition and DFRFT domain is used to embed the scrambling watermark into the original image. The experimental results show that this algorithm not only has good robustness, but also can effectively resist the external attack.