运用DFT的矢量地理数据零水印算法

A DFT-Based Zero-Watermarking Agorithm for Vector Geodata

针对目前矢量地理数据零水印算法鲁棒性差的问题,提出了一种基于DFT的矢量地理数据零水印算法。首先,利用Douglas-Peucker压缩算法提取矢量地理数据特征点;其次,对特征点进行DFT变换,得到矢量特征点的相位序列;接着,计算相位序列符号值,若该相位符号值大于等于0,其符号值为1,否则为0;然后,对N×N大小的水印图像进行Arnold置乱,得到置乱后水印图像;最后,从第2个相位符号值开始,选取前N×N个相位符号值构成特征矩阵并与置乱后的水印图像进行异或运算来构造零水印图像。实验结果表明该算法对平移、旋转等几何攻击具有鲁棒性,并对增点、删点攻击和坐标系转换攻击鲁棒性较好,具有一定的实用性。

Aiming at the problem that the robustness of the zero-watermarking algorithm for vector geodata is not strong,a zero-watermarking algorithm based on DFT for vector geodata is proposed in this paper. Firstly,DouglasPeucker algorithm is used to get key points of vector geodata. Secondly,the phase sequence of the key points is obtained using DFT. Further,the sign of phase is calculated,the value of the phase sign is 1 when it is greater than or equal to 0,otherwise,it is 0. And then,the watermarking image with size of N×N is scrambled using Arnold algorithm to obtain scrambled watermarking image. Finally,starting from the second phase sign value,the first N×N phase sign values are selected to form a feature matrix,which is executed an XOR operation with the scrambled watermarking image to construct a zero-watermarking image. The experiment results show the proposed algorithm is robust to geometric attacks such as translation,rotation,and so on. And it is robust to the attacks of adding points,deleting points and transformation of coordinate system,which proves that this algorithm has certain practicality.