Abstract
With the rapid development of communication and network, the transmission of multimedia, such as image, video and audio, is becoming more and more convenient. Hence, there exists a very important issue for the protection of intellectual property rights. Digital watermarking is a novel and developing technology, it has evolved very quickly for the past few years. A digital watermarking is the information, which is robustly and imperceptibly embedded in the multimedia data. Applications include copyright protection, authentication and data tracking. The distinct difference between the watermarking and encryption is that the data is only protected during the transmission using the traditional cryptography. After decrypting, however, the digital data is no longer protected, thus it is clear; it can still be copied and distributed. In contrast to cryptography, anyone can use the multimedia data, once the dispute about the ownership of data happened, we can extract the information from the host data to authenticate and characterize the owner by watermarking technique. Wavelet based coding, such as EZW and SPIHT, is an extremely successful compression algorithm, and has become the core technology of the up-coming image/video compression standards, which is well known, JPEG-2000 and MPEG-4. In this thesis, we will introduce a new multiresolution watermarking technology. The method is based on the discrete wavelet transform. Owing to the rapid growth of wireless communication, the transmission of multimedia is becoming fast and convenient. However, the data in transmission will suffer the channel noise and drop the quality of the transmission. To reduce the interference of channel noise, we also discuss the affection of additive white gaussian noise (AWGN) in our system. In this thesis, we interpret the watermarking technology based on communication concepts. The watermark is transmission signal, the frequency domain of original image is the transmission channel and the attacks are regarded as channel noise. Based on this architecture, we propose a quasi-blind watermarking technique and synchronization ideal, which can against JPEG coding, Wavelet-based coding and image shift attacks efficiently. In this framework, the attacks can be regarded as random noise, and which cannot affect the characteristic of AWGN channel (noise model). In addition, our watermarking technique does not need the original cover data to extract watermark, but some keys like “wavelet filters”, “side information” and “PN code” are necessary to increase robustness and security, on the other hand, the watermark is visually recognizable patterns; those are useful to against SWICO attack. To deserve to be mentioned, our proposed system can further be used in the DVD copy protection, the watermark can be used as copy control bits or embedded into video to prevent playback attacks. Consequently, the experimental results show our proposed system that is feasible and effective.