Fake Watermark Embedding Scheme Based on Multi-Stage VQ

Abstract

A multiple fake-watermark embedding system based on multi-stage vector quantisation (MSVQ) for security enhancement is given in this chapter. This system first creates a non-recognizable reference watermark by referring to the genuine watermark and a number of fake watermarks. It then performs the MSVQ to encode the cover image. In each stage of the MSVQ system, a polarity stream is established according to the VQ indices obtained. The exclusive-OR (XOR) operation is then applied to the polarity and the corresponding watermark, which may be a fake watermark or the reference watermark, so that a user key can be created. To reveal the genuine watermark, the MSVQ is first performed on the watermarked image. In each stage of the MSVQ system, a watermark can be extracted using the key generated previously. By stacking all the extracted watermarks together, the original watermark can be recovered.

Due to the use of visible fake watermarks, the security of the watermarking system is improved. Moveover, by assigning the keys generated to the related users, the introduced system allows multi-users to share the hidden information together.