一种基于Cox算法的分块DCT图像水印算法研究

Research on a DCT Image Watermarking Algorithm based on Block Classification

介绍了DCT域图像水印技术,详细分析了经典的Cox算法和一种基于块分类的自适应图像水印算法;通过分析图像在流通中可能经常遇到的一些信号处理、几何变换以及可能性攻击,对水印算法进行了分析、实验和测试。Cox算法是一种基于DCT变换的扩频水印技术,它将高斯随机序列加入到图像的DCT变换后视觉最重要的系数中。基于块分类的自适应图像水印算法将原始图像分块并设计了一个基于视觉掩蔽特性的分类器,根据分类的结果,不同强度的水印分量被嵌入到不同图像块的DCT低频系数中。实验结果表明,DCT域算法得到的水印图像失真小,对于基本的图像处理操作具有较强的鲁棒性。

This paper introduces image watermarking technology in DCT domain,detailedly analyzes classic Cox algorithm and an adaptive image watermarking algorithm based on block classification,then carries on the implementation of the corresponding algorithm and realizes the analysis,experimentation and simulation of the corresponding algorithm.In Cox algorithm,Gaussian random vector that is imperceptibly inserted in a spread-spectrum-like fashion into the perceptually most significant spectral components of the image data.The adaptive algorithm based on block classification splits the original image into blocks and classifies these blocks based on visual masking.Watermark components with different strength are inserted into some DCT coefficients according to the classification.Simulation results of the algorithm show that DCT domain algorithms have little distortion.At the same time,it is robust to common image processing techniques.