Research Of Wavelet Packet And Wavelet Digital Image Watermarking Scheme Based On Chaos Encryption

Digital watermarking algorithm offers a way for application problem. Copyright protection is one of an important watermarking algorithm application. This paper mainly researches image watermarking algorithm on wavelet packet and wavelet transform, also combines new chaos encryption theory. Wavelet packet and wavelet transform are hot research domain, among them, Wavelet packet has broader application value, because wavelet packet decomposes high frequency further and offers broad frequency bands. Chaos encryption theory is a traditional encryption technique and a new idea has appeared based on it in this paper.This paper firstly gives a brief introduction of basic knowledge about watermarking algorithm including its production, basic framework, types, function norms of evaluation and main applications. Detailed introduce research works of internal and overseas and briefly introduce some image watermarking algorithm technology.Then, introduce chaos theory basis, encryption technology and wavelet, wavelet packet analysis theory respectively. Chaos theory basis includes non-linear, its definition, characters and several chaos maps. Emphasize application of chaotic sequence later. Make a description of three aspects those are frequency analysis, definition and decomposition and recompose while introducing wavelet and wavelet packet.From the fourth to sixth chapter, presented three different watermarking algorithms based the former knowledge. These contents showed as the following.Algorithm one is "A wavelet packet watermarking algorithm based on chaos encryption". This algorithm researches a new encryption method, use module arithmetic for initial encryption and produce a random sequence by using characters of chaotic sequence, lastly do last encryption on them. Watermark embedded in high frequency sub band of low frequency after wavelet packet decomposition and embedded in coefficient after transform directly. Adjust embedding depth by result of experiment.Algorithm two is "A chaos-based and hybrid SVD-DWT watermarking algorithm". This algorithm combines SVD (Singular Value Decomposition) and DWT (Discrete Wavelet Transform) domains. In the embedding stage, partition the original images into 8×8 blocks, extract the sub images from the original images by chaotic sequence then a DWT is applied for the extracted sub images. A SVD transform is applied for the watermark image, only the singular values of the watermark need to be embedded into the coefficients of sub bands of the original sub image. Singular values are grouped by two, embedded in coefficients of different bands and frequencies and embedding depths are different.Algorithm three is "A wavelet packet blind watermarking algorithm based on chaos encryption". It realizes blind extraction basis of algorithm one and two. Blind extraction uses relationships of wavelet packet coefficients.Finally, it's overall summarization of this paper and forecasting of further research work.