中文摘要：

能有效检测经过信号处理和几何攻击之后的版权图像是当今拷贝检测研究的热点和难点之一.现有基于图像分块的拷贝检测算法在图像经过旋转和缩放变换后分块内容变换较大,检测效果较差.针对上述问题,提出一种基于整体DCT系数顺序测度的鲁棒图像拷贝检测方法,选取彩色图像YCbCr颜色空间Y平面整体DCT变换后的中低频系数,计算其顺序测度作为图像特征矢量.由于整体DCT中低频系数随着图像缩放有规律的变化,引入顺序测度提取中低频系数的序列作为图像特征,因而对缩放失真具有较好的抵抗力,同时能很好地抵抗信号处理攻击;提出旋转补偿策略,使本算法能抵抗30°以内的旋转变换攻击.实验结果证明在抗拉伸和旋转攻击方面,给出的算法相对于已有算法具有较高的查全率和查准率.

英文摘要：

To effectively detect copyrighted images suffering both single processing attacks and geometrical attacks is one of the hotspots and difficulties in the image copy detection research.For most existing block-based image copy detection algorithms,the performances can successfully resist to the noise-like distortion,but they are quite fragile to geometric attacks,such as rotation,shift,translate,scale,cropping and so on,because the content of each block is changed after these kinds of attacks.In this paper,a robust image copy detection algorithm based on ordinal measure of the full DCT coefficients is proposed.The ordinal measure of the selected low and middle frequency coefficients which are calculated from full DCT transformation on Y-component of YCbCr color space is used as the image eigenvector.The middle and low frequency full DCT coefficients are changing regularly with scaling,so the proposed method can resist scaling distortion.Meanwhile,the ordinal measure is introduced to resist single processing attacks.Moreover,the rotation compensation strategy used in this algorithm can resist the rotation attacks in which the angles are less than 30°.The experimental results show that the algorithm has higher precision and recall rate than the existing methods in terms of rotation and scaling distortion.