A survey of watermarking techniques applied to multimedia

In the early days, encryption and control access techniques were used to protect the ownership of media. Recently, the watermark techniques are utilized to keep the copyright of media. Digital watermarking, a concept of embedding a special pattern, uses an algorithm of inserting a watermark to protect the copyright of media. It has recently become important in various application areas. The various of watermark techniques have been proposed by many authors in the last several years. However, there are not enough analysis and comparison on the previous researches. In this paper, for the understanding of the previous works and for the future related research, the authors try to classify and analyze the conventional watermark techniques from the various points of view. Currently watermark techniques based on the transfer domain, are more popular than those of the spatial domain. DCT-based methods have been most widely used among the transform based methods. However, recently wavelet-based watermark techniques are becoming the main research topic. With wide use of the internet, effective audio and video watermarking researches are also required.