摘要： 目前图像哈希领域中许多算法只能处理灰度图像,为扩大算法适用范围,同时提高图像哈希算法的性能与旋转攻击的鲁棒性,提出基于四元数拉盖尔矩和三维能量结构的哈希算法。首先对输入的彩色图像进行预处理与多尺度融合处理,将融合图像提取的拉盖尔矩系数作为图像的全局特征,同时在YCbCr颜色空间中利用融合图像的能量信息建立模型,选取三维模型中不同视角下的能量峰值和谷值点连线与水平面的夹角作为局部结构特征;然后根据特定点与三维模型各条等高线上近点和远点的位置提取具有旋转不变性的特征;最后结合全局特征和三维结构特征,量化并加密生成哈希序列。实验结果表明,该算法在鲁棒性与区别性之间有更好的平衡,受试者工作特征曲线错误接受率为0时的正确接受率达到0.999 2。当哈希序列长度为120 bit时具备最优的紧凑性,平均计算时间为0.097 9 s。在拷贝检测实验中,该算法进行多次抽取实验的平均查全率和查准率均在95.83%以上。

关键词: 四元数拉盖尔矩, 图像哈希, 图像能量, 三维结构特征, 拷贝检测

Abstract: Currently, several algorithms used in image hashing can only handle grayscale images. In this study, a hashing algorithm based on quaternion Laguerre moments and a three-dimensional energy structure is proposed to improve the range of application and performance of the image hashing algorithm, particularly its robustness against rotation attacks. First, the input color image is preprocessed, multiscale fusion is performed, and the Laguerre moment coefficients are extracted from the fused image as the global features of the image. The energy information of the fused image is used to establish a model in the YCbCr color space, and the angle between the energy peak and valley points connected with the horizontal plane at different viewpoints in the three-dimensional(3D) model is selected as the local structure feature. The features with rotational invariance are extracted by the positions of the near and far points on the specific points and each contour of the 3D model. Finally, the global and 3D structural features are combined, quantized, and encrypted to generate hash sequences. Finally, the global and 3D structural features are combined to quantify and encrypt the generated hash sequences. The results show that the subject operating characteristic curve exhibits a correct acceptance rate of 0.999 2 when the error reception rate is 0. A Hash sequence length of 120 bit possesses optimal compactness, and the average computation time reaches 0.097 9 s. In copy detection experiments, the algorithm performs multiple extraction experiments with an average check-all rate, and the average check rate and accuracy rate of the algorithm for multiple extraction experiments are higher than 95.83%.

Key words: quaternion Laguerre moments, image Hash, image energy, three-dimensional structural features, copy detection

中图分类号: 

• TP391