Reversible Difference Expansion Embedding Using Two Edge Directions

Difference expansion is a very important technique in reversible data hiding field. Reversibility allows secret message to be completely recovered without any distortion after data extraction. Specifically, difference expansion embedding performs integer transform in a difference image which is acquired by grouping two neighboring pixel values. This paper proposes an improved reversible difference expansion embedding scheme. The main idea of this scheme is to consider edge direction to decrease the difference of two neighboring pixels values. In general, the larger difference tends to bring a degraded stego-image quality than the smaller difference. Experimental results showed that the proposed scheme improves image quality of PSNR from 0.5 to 3.7 dB in average. At the same time, the performance for payload is almost constant in comparisons with previous method.