Context embedding for raster-scan rhombus based reversible watermarking

Abstract

The embedding not only into the current pixel, but also into the prediction context was recently proposed as an improvement of difference expansion reversible watermarking algorithms. So far it was shown that the effect of splitting the data between the current pixel and the prediction context decreases the embedding distortion, but increases the prediction error. This paper revisits the case of context embedding for the case of pixel prediction on the rhombus composed of the two vertical and the two horizontal neighbors. For this case it appears that the context embedding can be used not only to reduce the embedding distortion, but also to improve the prediction. The gain provided by the improvement of the prediction outperforms the one provided by the reduction of the embedding distortion. Experimental results are provided.