Histogram-pair based reversible data hiding via searching for optimal four thresholds

A histogram-pair based image reversible data hiding (RDH) scheme is presented in this paper. It embeds data into the prediction-errors generated from a cover image. In doing so, instead of changing a prediction-error x to 2x + b as done in most existing RDH algorithms, where b is a to-be-embedded binary bit, we modify the quantity x to x + b so as to reduce the embedding distortion. Moreover, four thresholds, i.e., the embedding threshold, the fluctuation threshold, the right- and the left-end histogram shrinking thresholds, are employed and adjusted to achieve the highest PSNR at a given embedding rate. The experimental results have demonstrated that, comparing with the state-of-the-arts works, superior performance can be achieved by the proposed method. Particularly, by the proposed histogram shrinking, better embedding result can be achieved for the cover image with high peak bins at both sides of the image spatial histogram (e.g., the JPEG2000 test image Woman).