The success of Internet and the promise of higher bandwidth and quality of service (QoS) for both wired and wireless networks has made it possible to create, replicate, transmit, and distribute digital content in an effortless way. The protection and enforcement of intellectual property rights for digital media has become an important issue. Among the possible approaches to the protection of copyrighted data, digital watermarking is receiving increasing attention, as it represent a viable solution to data protection in open, highly uncontrolled, environments where cryptographic techniques cannot be applied successfully. Watermarking is the direct embedding of additional information into multimedia signal. Ideally, there should be no perceptible difference between the watermarked and original signal, and the watermark should be difficult to remove or alter without damaging the host signal. Applications for digital watermarking include copyright protection, fingerprinting, authentication, copy control, tamper detection, and data hiding applications such as broadcast monitoring. In this paper, we limit the scope of our research to robust and imperceptible digital watermarking for copyright protection.The first step in the study of a watermarking system is the issue of watermarking source coding. This is a crucial issue, since watermark properties must highly depend on the protected data in order to be imperceptible. In communications approach, the main aim of source coding is data compression. But in watermarking system, the main aim of source coding is watermark shaping. In this paper, we proposed three approaches: watermark scrambling, amplitude shaping and adaptive prediction-based frequency domain shaping. On the other hand, the interference between the host data and the watermark signal plays a crucial role in the design of a robust watermarking scheme, especially in blind systems, where watermark recovery is performed without any reference to the original, non-marked multimedia data. Early systems modeled the host data as a disturbing noise limiting the effectiveness of watermark communication. However, a theoretical analysis reveals that it is possible to compensate for host datainterference by properly designing a whitening filter.In order to improve watermarking robustness against distortions and attacks, it is natural to envision the use of error correcting codes (ECC). In this paper, we consider the concatenation of Bose-Chaudury-Hocquenheim (BCH) and repetition codes and present soft-decision decoding schemes based on a MAP (Maximum A Posterior probability) criterion. We compare the performance of watermark decoding under both hard-decision and soft-decision schemes. In addition, fast decoding algorithms are also proposed and the corresponding performance is analyzed. We make a study of the application of shuffling techniques within watermarking and present criterion measure on shuffling degree. The criterion measure can help me to decide how to shuffle an image in order to obtain the best robustness. Two different applications within watermarking system are presented and compared, Computer simulations indicate that these techniques are very effective in respect of keeping resilience to cropping attack.Digital watermarking of multimedia (e.g., audio, images, video, etc.) can be viewed as a communications problem in which the watermark must be transmitted and received through a "watermark channel". Current analyses of the watermarking channel are typically limited to the additive white Gaussian noise (AWGN) channel. In this paper, we introduced two watermarking channel models and analyzed discrete cosine transform domain (DCT domain) watermarking channel model for copyright protection of still digital images. The DCT is applied in blocks of 8X8 pixels as in the JPEG algorithm. We apply Generalized Gaussian distributions to statistically model the DCT coefficients of different natural images. As a result of our work, fast estimating expression for channel model parameters are derived