Research And Improvement Of Visible Reversible Digital Watermarking Algorithms

Visible reversible watermarking scheme embeds a video watermark in original image as an copyright symbol, and this symbol can be removed to restore the original image. Therefore visible reversible watermark can be used as an effective mean for digital image copyright protection.In this paper the key algorithms of watermarking scheme are discussed and analyzed. An improved pixel value matching algorithm and an improved watermark encryption scheme are proposed based on the original algorithms respectively.Based on the existing value pixel matching algorithms, this paper proposed an improved algorithm to perform image copyright protection. The improved algorithm overcomes the noise phenomenon by changing the fixed variation of pixel value into variable variation. The improved algorithm also blend embedding factor into the matching formula to control the strength of watermark and increase the definition of watermark in texture image. Simulation results show that this algorithm can effectively overcome the noise phenomenon of the original algorithm and improve the definition of watermark in texture image.This paper also presents a new watermark encryption scheme to improve the unpleasant encryption result with texture image of original encryption algorithm. In the encryption phase divide the image into 2×2 blocks and multiply every block with 2×2 matrix determined by the user key to show interference bitmap in the watermarked region for encryption function. Unauthorized recover experiment and collusion attacks experiment show encryption effectiveness of texture image with the new algorithm was better than the original encryption algorithm. The noise phenomenon on recovery image using the original encryption algorithm is not obvious and the encryption effect is unpleasant,but recover images using new encryption algorithm can still show obvious disturbance bitmap and the security of watermark is improved.