Reversible image watermarking using modified difference expansion

Reversible watermarking (RW) using difference expansion (DE) is quite popular to embed data followed by recovery of the original image. According to this algorithm, the least significant bit (LSB) of inter-pixel differences (between a pair of neighboring pixel) is used to embed watermark data. In the existing DE based works, a large part of the embedding space is used by auxiliary embedding information; hence, effective payload is sacrificed. To this aim, a modification in DE is proposed here that not only increases embedding space but also makes an improvement in imperceptibility and security of the hidden data. Simulation results show an improvement of 2.29 dB in visual quality and 0.002605 in security (Kullback-Leibler distance) measure at 0.49 bpp watermark payload.