A novel blind watermarking based on lattice vector quantization

As the complement of cryptography in multimedia security, digital watermarking has been researched in last ten years due to concern about illegal piracy of copyrighted content. Most transform-domain watermarking techniques are based on discrete cosine transform (DCT), discrete Fourier transform (DFT) and discrete wavelet transform (DWT). Among all these algorithms, the blind watermarking scheme is challenged and needed in many practical applications. In this paper, we propose a novel oblivious watermarking based on lattice vector quantization in DCT domain. A trade-off between robustness of watermark and the quality of the watermarked image is achieved by varying quantization factor for watermark embedding. Experimental results show that new scheme is robust against intentional and incidental attack such as JPEG compression, addition of noise, filtering and so on without degrading image quality. These results can be combined with a private key-based scheme to make unauthorized retrieval practically impossible, even with the knowledge of the algorithm.