Digital Image Watermarking Method Of Communication

Generally speaking any watermarking system can be seen as a communication system consisting of two main parts: a watermark embedder, and a watermark detector. To improve the robustness of watermark, all kinds of error-correction coding techniques have been introduced to digital image watermarking system. Although this may have an effect on bringing a lower detection error rate, the theoretical performance analysis is insufficient. Through this paper, the statistical characteristic of the frequency domain noise is first derived, and an equivalent communication channel model is also obtained. The authors have proved that under Gaussian attacks, the frequency domain watermarking channel can be regarded as a power given and bandwidth limited Gaussian noise channel. Thus traditional communication theories can be used in watermarking system directly. A theory upper bound performance is also proposed when channel coding is utilized. Furthermore, TCM is recommended for the purpose of lowering the error rate if the bandwidth is limited. Both theoretical analysis and simulation results show its advantage. This paper also presents an error control coding based fragile watermarking algorithm, which can authenticate an image without using original watermark. Besides the use of error control coding ,we also introduce the Turbo iteration idea to digital watermarking system in a creative way. Due to the differences between this two system, this paper have finished a preliminary research and discuss on a Non-communication field iterate rules. Also, some performance of this iterate system is theoretically estimated.