A High Secure Reversible Visible Watermarking Scheme

A novel reversible visible watermarking algorithm is proposed. It can fully remove the watermark from the visible watermarked image such that the original image can be restored. Pixel values of original image beneath the watermark are mapped to a small range [alpha, alpha + 127] to generate a visible watermarked image. Since the mapping is many-to-one, taking inverse mapping can only approximate the original image. To restore the original image, the difference image of subtracting the approximated image from the original image and other side information are losslessly compressed to be embedded in the visible watermarked image by a reversible data embedding algorithm. We proposed a key-based scheme for the compromise between transparency and robustness. The key is a random variable with discrete normal distribution. In addition, only users with correct key can restore the original image. In the experimental results, we show the transparent degree of watermark can be controlled by the variance of the key. Users with wrong key can not restore the original image from the visible watermarked image.