Mapping Based Reversible Watermarking

International audienceThe set of pairs of pixels is partitioned into disjoint groups of equal number of pairs. Furthermore, a subset of pairs of pixels is selected and each pair is uniquely associated with a group of the partition. If the size of the groups is m, log2m bits of data can be embedded into an image pair by replacing it by the pairs of a group. As long as at detection one can find if a pair was replaced or not, the transform is reversible. Hence a reversible watermarking scheme is obtained by embedding together with the watermark the information needed to locate the transformed pairs. The paper discusses how to select the subset of pixel pairs and the partition in order to obtain high capacity watermarking schemes. It is also shown that a recently proposed reversible scheme is based on this principle. Due to its flexibility, the general scheme is expected to introduce less distortion. The experimental results obtained so far are promising