Three stages prediction-error expansion reversible watermarking

This paper proposes a three-stages difference expansion reversible watermarking scheme. In the first stage, a quarter of the pixels are estimated by using the median of the eight original neighbors of the 3×3 window. In the second stage, a quarter of the pixels are estimated as the average on the rhombus of the four horizontal and vertical original pixels. Finally, the remaining pixels are estimated on the rhombus context, using the modified pixels computed in the two previous stages. The experimental results show that the proposed scheme can provide slightly improved results than the classical two-stages reversible watermarking based on the rhombus context.