Reversible Watermarking Scheme with Image-independent Embedding Capacity

Permanent distortion is one of the main drawbacks of all the irreversible watermarking schemes. Attempts to recover the original signal after the signal passing the authentication process are being made starting just a few years ago. Some common problems, such as salt-andpepper artefacts due to intensity wraparound and low embedding capacity, can now be resolved. However, we point out in this work that there are still some significant problems remain unsolved. Firstly, the embedding capacity is signal-dependent, i.e., capacity varies significantly depending on the nature of the host signal. The direct impact of this ill factor is compromised security for signals with low capacity. Some signal may be even non-embeddable. Secondly, while seriously tackled in the irreversible watermarking schemes, the well-recognized problem of block-wise dependence, which opens a security gap for the vector quantisation attack and transplantation attack are not addressed by the researchers of the reversible schemes. It is our intention in this work to propose a reversible watermarking scheme with near-constant signal-independent embedding capacity and immunity to the vector quantisation attack and transplantation attack.