Reversible image watermarking based on a generalized integer transform

In this paper, a recently proposed reversible image watermarking algorithm based on reversible contrast mapping (RCM) is further developed. The integer transform, RCM, which is originally defined on a pair of integers, is extended to integer array of arbitrary length. Based on this generalization, the embedding capacity can be significantly increased. Meanwhile, the embedding distortion is well controlled by a suitable selection of embeddable pixel blocks. In fact, the hidden data is priorly embedded into the blocks that introduce less distortion. Furthermore, the proposed scheme does not need additional data compression, and it has low computational complexity. The experiments verify that the novel scheme outperforms the original RCM-based method and some state-of-the-art reversible watermarking algorithms, especially the ones based on integer transform.