基于拉普拉斯分布模型的DCT域图像水印视觉可见性评估

Evaluating the Visibility of Image Watermarking in the DCT Domain Based on Laplacian Model

数字水印是数字作品版权保护的重要技术途径之一 .随着数字水印技术的不断应用 ,数字水印产品的测评工作已经引起相关信息安全管理部门的高度重视 ,建立水印测评理论基础的需求越来越迫切 .视觉可见性是数字水印测评的重要技术指标之一 .本文根据DCT交流系数的拉普拉斯分布模型 ,对DCT域的典型水印嵌入算法的视觉可见性进行了评估 ,推导了水印嵌入深度 (拉伸系数 )与信噪比和峰值信噪比之间的理论关系 ,实验结果表明理论估计具有很高的精度 ,误差小于 1分贝 .

Digital watermarking is a key technique for protecting intellectual property of digital media. As a number of methods have been proposed in recent years to embed watermarks in images for various applications, evaluation of watermarking algorithms becomes more and more important. Watermark visibility, which can be measured by signal to noise ratio (SNR) or peak signal to noise ratio (PSNR) ,is one of the major performance indexes of watermarking algorithms. In this paper, based on the Laplacian distribution model of AC DCT coefficients, we deduce theoretical relationship between the scaling parameter in some typical watermarking algorithms and the degradation of watermarked images. Experimental results show that the evaluated error of SNR and PSNR is less than 1 dB.