Reversible watermarking based on PMO of triplets

A reversible watermarking algorithm based on piecewise modification operation(PMO) of triplets is proposed in this paper. PMO is designed to embed a bit into any two pixels while remaining the intensity sum of pixels unchanged. Two bits are embedded into a triplet by repeatedly using PMO on every two neighboring pixels. Another advantage of using PMO is that the capacity consumed by the additional information can be largely decreased. As a result, the embedding capacity is considerably increased. A series of experiments is conducted to verify effectiveness and advantages of the proposed approach.