基于小波视觉模型的乘性水印算法

Multiplicative watermarking algorithm based on wavelet visual model

虽然小波域加性水印算法具有较好的不可感知性,但其鲁棒性较弱。因此,结合小波域视觉模型,提出了一种基于小波视觉模型的乘性图像水印算法。在水印嵌入过程中,为平衡水印的不可感知性和鲁棒性,以中频子带作为水印嵌入空间,并根据图像的频域敏感度、亮度敏感度、纹理复杂度确定水印的嵌入强度。在水印检测过程中,采用广义高斯分布(GGD)对小波系数的统计特性进行刻画,并通过奈曼—皮尔逊(NP)准则确定水印系统的检测阈值,给出了水印系统的虚警概率和检测概率之间的接收者操作特征(ROC)曲线关系。最后通过实验测试了该算法在抗压缩、叠加噪声、缩放和剪切等攻击时的鲁棒性能。仿真结果表明:该算法具有较好的检测性能以及在抗攻击时具有较强的鲁棒性。

The additive watermarking algorithm has good imperceptibility,however,the robustness of watermark is poor.As a result,a multiplicative image watermarking method was proposed by combining the visual model in the wavelet domain.In the proposed embedding scheme,the middle-frequency subband acted as the watermark embedding space,which was used to achieve the tradeoff between the imperceptibility and the robustness of watermarking system.Besides,the embedding strength factor was determined by considering the frequency masking,luminance masking and texture masking of host image.In the proposed detection scheme,the probability density function of wavelet coefficients was modeled by the Generalized Gaussian Distribution（GGD）,and the watermark decision threshold was obtained by using the Neyman-Pearson（NP） criterion,and the Receiver Operating Characteristic（ROC） curve between the probability of false alarm and the probability of detection was derived.Finally,the robustness of the proposed watermarking was tested when being against common image processing attacks such as JPEG compression,Additive White Gaussian Noise（AWGN）,scaling and cropping.The experimental results demonstrate that the proposed method has good detection performance and good robustness.