Research Of Static Image Watermarking Algorithm Based On Wavelet Domain

With the rapid development and wide application of network and multimedia technology, the transportation and trade of digital multimedia information is becoming very convenient, and the digital copyright has become more important at the same time. Digital watermark is a new rising method of copyright protection in the field of information security in recent years, which is a new technology to protect copyright, source of authentication and integrity under the open network environment. Because of the characteristics of multi-resolution analysis and multi-scale analysis, Wavelet Analysis has been widely used in image processing. With the application of Wavelet Analysis in watermarking algorithm, we could get a better coordination of the contradiction between the robustness and invisibility of watermark. At present, the watermark algorithm based on wavelet domain attracts high attention and becomes a hotspot of research.In this paper, we firstly introduce the development and basic concepts of digital watermark; we introduce the wavelet theory, multi-resolution analysis, Mallat algorithm and analyze the principle of image wavelet decomposing and composing. Secondly we propose two improved watermarking algorithms based on wavelet domain. (1)An improved watermarking algorithm based on block energy analysis of the wavelet transform parameters: In the wavelet domain, we divide detail sub_images into several blocks. According to the further statistics and analysis of the block energy, we select the slice which has the largest energy for the region where watermarking information is embedded. We make use of the Logistic mapping to normalize the result into 0, 1 sequence as the watermarking information embedded in the vector image directly. This algorithm coordinates the contradiction between the robustness and invisibility to a certain extent, and it has better robustness and strong resistance to the attack of cryptanalysis. (2)An improved digital watermarking algorithm based upon relation in wavelet domain: This algorithm is based on the second generation wavelet algorithm upgrade. Firstly we pretreat the watermark on the use of Arnold transform and decompose the vector image on the use of wavelet transform; secondly, according to the size relationship of wavelet transform parameters watermarking information is embedded adaptively. This is a simple blind watermarking algorithm, and it has a faster operational speed. The experimental results show that the algorithm has good robustness and impercipience.Finally we review entire work. Something need to research in the next step is pointed out. And we suggest the direction for the future research of watermarking.