Improved control for low bit-rate reversible watermarking

The distortion introduced by reversible watermarking depends on the embedding bit-rate. This paper proposes a fine control of the embedding bit-rate for low capacity histogram shifting reversible watermarking. The basic idea of our approach is to split the prediction error histogram into several histograms and to ensure the fine tuning of the bit-rate by selecting the appropriate bins for each histogram. The splitting is performed as a function of the prediction context. The bins (two for each histogram, one for the right side, another for the left side of the histogram) are selected by linear programming in order to minimize the distortion introduced by the watermarking. The proposed scheme outperforms in terms of embedding distortion the prior state of the art.