采用复合整数变换差值扩大法的矢量地图可逆水印算法

现有的二维矢量地图可逆水印算法没有充分考虑原始地图的形状特征,其有效信息嵌入率较低,水印嵌入带来的失真较大,为此提出一种有效的二维矢量地图可逆水印算法.该算法考虑二维矢量地图的结构特点和形状特征,利用矢量地图曲线和曲面坐标序列固有的分段单调性来构造多维向量;对多维向量实施复合差值扩大可逆变换,将水印嵌入引入的误差由多个数据点共同承担,使得每个数据点所承受的误差更均匀,避免了在矢量地图单调转折区因水印嵌入带来较大的失真,使矢量地图能承载更多的有效信息;通过设定矢量地图的误差容限来保证精度,可有效地控制信息的嵌入大小.理论分析和实验结果表明,该算法具有较好的透明性和较高的有效信息载荷,可用于矢量地图认证和隐秘通信等领域.

Reversible Watermarking Algorithm for Vector Maps Using the Difference Expansion Method of a Composite Integer Transform

Current reversible watermarking algorithms for 2D vector maps do not consider the shape characteristic of 2D vector maps. The obvious disadvantage of these techniques is that vector map quality may be severely degraded with low data hiding capacity. This paper presents an effective reversible watermarking algorithm for 2D vector maps. In the algorithm, through analyzing the characteristic of vector maps, multidimension vectors are constructed from the subsection monotonicity of coordinates of curves and polygons, and a composite difference expansion integer transform is proposed and used for the multidimension vectors. Thus, a large payload can be embedded into a vector map with low distortions in the monotonous transition zones of a stego-map. In addition, by setting the threshold of error tolerance, the length of embedded data is controlled. Theoretical analysis and experimental results show that our algorithm allows for hiding high payload with low distortions. The potential applications of proposed scheme may include vector map authentication, secret communication, etc.