Reversible watermarking based on invariant sum value for 2D vector maps

A simple reversible watermarking scheme for 2D vector maps is presented in this paper. When embedding data, the proposed scheme applies an integer transform for a pair of coordinate values to embed 1-bit watermark and makes the sum of the coordinate values unchanged. When extracting the embedded data, the proposed scheme gets the watermark bit and recovers the original data by using the invariant sum value and the parities of the sum value and the difference value. The coordinate values not for embedding are shifted. In the decoder, the marked pairs can be determined from the unmarked pairs by the ranges that their differences fall into. Hence, the proposed scheme does not need to compress and embed the location map. Therefore, the computational complexity is low and the capacity is high. Experimental results show the proposed scheme has good performance.