对基于量化水印的两频带滤波攻击的估计

提出了一种基于量化水印的两频带幅值比例攻击的估计算法。基于量化的水印算法在有加性噪声攻击的情况下可以达到信道容量,然而对线性时不变滤波攻击没有鲁棒性。该文集中考虑一种使用滤波器组调整信号频谱的多频带幅值比例攻击,给出受攻击信号的概率密度函数(PDF)模型;使用这个PDF模型的简化近似;给出两频带滤波攻击幅值比例因子的最大似然估计方法。以合成的音频信号进行实验,结果显示出所提出的估计技术的有效性。

Two-Band Amplitude Scale Estimation for QIM Watermarks

This paper presents a scheme for estimating two-band amplitude scale attack within a quantization-based watermarking context.Although quantization-based watermarking schemes achieve the channel capacity in terms of additive noise attacks,these schemes are not robust against linear time invariant filtering attacks.We concentrate on a multi-band amplitude scaling attack that modifies the spectrum of the signal using an analysis/synthesis filter bank.First we derive the probability density function (PDF) of the attacked data.Second, using a simplified approximation of the PDF model,we derive a maximum likelihood (ML) procedure for estimating two-band amplitude scaling factor.Finally,experiments are performed with synthetic audio signals showing the good performance of the proposed estimation technique under realistic conditions.