Reversible digital watermarking scheme for 2-D vector maps based on difference expansion and shifting
Guozhao Wang · Journal of Optoelectronics·laser · 2009
Based on the difference expansion and difference shifting,a novel reversible watermarking algorithm for digital vector map is proposed.The watermark is embedded by modifying the vertices coordinates.Instead of difference expansion,the difference of every adjacent coordinates is divided into three parts:one is shifted right if the difference is bigger than K-1;the second is shifted left if the difference is smaller than -K;and the third part is used to expand and embed the watermark (Kis a positive integer chosen by the user).At the same time,the distortion caused by expansion and shifting is uniformly separated into the two pixels,which keeps the lower distortion.Experimental results demonstrate that the proposed scheme can embed a larger payload while keeping the lower root mean square error (RMSE).