Digital image watermarking using DCT and z-score transform

Owning to the rapid development of Internet, users have more chances to use multimedia data and digital contents. As a result, illegal reproduction of digital information started to pose a real problem. Digital watermarking has been regarded as an effective solution to protect various kinds of digital contents against illegal use. In this paper, a watermarking technique which applies the discrete cosine transformation and z-score transformation is presented. In order to improve the performance of watermarking technique, a genetic algorithm is used to search proper parameters which are used to control the watermark strength. Experimental results demonstrates that the proposed technique is able to withstand a variety of attacks.