基于缩放不变矩的鲁棒DCT域图像拷贝检测方法

提出一种基于不变矩的DCT域图像拷贝检测方法, 选取图像亮度分量的整体DCT变换后的中低频系数的符号作为其DCT域特征, 分别计算原始图像及其角度规范化后图像的DCT域特征, 计算并比较查询图像与图像库中图像的两类特征的相关性, 取较大的相关值来判断图像是否存在拷贝. 图像的整体DCT中低频系数已被验证对于信号处理攻击鲁棒性高, 且随着图像缩放攻击呈规律性变化, 因而利用图像的整体DCT中低频系数构建的DCT域特征对于信号处理和图像缩放攻击鲁棒性高; 利用图像的缩放不变矩估算出图像特征角度, 再依据特征角度对图像进行角度规范化可消除旋转失真的影响, 因而利用角度规范化后的图像的DCT域特征能抵抗旋转、以及旋转和等比例缩放的混合攻击. 实验结果证明在抗旋转和包含旋转的混合攻击方面, 该算法的检测效果明显优于已有算法.

Scale-Invariant Moment Based Robust Image Copy Detection in DCT Domain

In this paper, an invariant moment based robust image copy detection algorithm in discrete cosine transformation (DCT) domain is proposed. Low and middle frequency coefficients which are calculated from full DCT transformation on luminance component of image are used as the image eigenvector in DCT domain. The query image and its angle normalized image eigenvector in DCT domain are computed, then correlation values of two eigenvectors of the query image and those of test image are respectively computed and the larger one is used to judge whether the query image is a copy or not. Full DCT coefficients are verified to have high robustness against common signal attacks and regularly vary with scaling attacks, thus the DCT eigenvector constructed by middle and low frequency full DCT coefficients can resist signal attacks and scaling distortion. The characteristic angle estimated by the image scale invariant moment is used to normalize the image to counteract the rotation distortion, so the angle normalized image can resist rotation distortion. The experimental results show that the algorithm is superior to Ling's methods in terms of rotation distortion.