Watermarking Algorithm based on the DWT

Watermarking is considered as a desirable alternative for copyright protection of digital materials such as images, video and audio. Two kinds of watermarking algorithms are usually used: the watermarking algorithms using pseudorandom patterns and those using visual recognizable patterns. The main advantage of watermarking algorithms embedding a visual recognizable pattern, which can be the owner or provider logotype, is that after the extraction process the pattern can be visually recognized and then identified. In general the visual recognizable patterns has a large impact and less ambiguity during the copyright claim process as compared with the random patterns, however the amount of information required by the visual recognizable pattern is much larger than the amount of information required by the pseudorandom one, and then to achieve imperceptibility and robustness of the watermark is more difficult. This paper proposes a discrete wavelet transform (DWT) based watermark embedding algorithm for visual recognizable pattern which uses the relation between the human visual system and the DWT for embedding the watermark is such way that it becomes imperceptible and robust. Evaluation results show the desirable features of proposed scheme.