Multibit versus multilevel embedding in high capacity difference expansion reversible watermarking

The classical difference expansion (DE) reversible watermarking expands two times a difference in order to embed one bit of data. The upper limit of such DE schemes in a single embedding level is usually bounded by 1 bpp. In order to obtain more than 1 bpp, several embedding stages are chained. The multibit DE schemes expand n times the difference in order to embed up to log₂ n bpp. This paper proposes a multibit extension of the difference expansion reversible watermarking and compares the results with the multilevel embedding case. The multibit reversible watermarking outperforms the multilevel one both in capacity and quality. Experimental results on standard test images are provided.