Digital Watermarking Algorithm Based On Chaos And Discrete Fractional Fourier Transform

As the rapid development of information technology and computer networks, the storage, replication and dissemination of the digital multimedia information has become very convenient. We are enjoying the pleasure and convenience of visual and aural enjoyment of the multimedia messaging technology. We can quickly and easily access via the Internet, or by copying. However we have no restrictions on copy, distribute and modify the edit multimedia messages. How to protect the copyright and economic interests of digital media, the security issues of the digital multimedia information, trustworthiness, the resulting problems caused by infringement and illegal copy have increasingly become a serious social problem. Therefore, the protection of the copyright and contents of the digital multimedia digital information has become an urgent problem to be solved.The cryptography is one of the major traditional technologies in the field of information security. It is based on information theory and cryptography theory of Shannon technology, generally change plaintext into ciphertext encrypted to control the file access. However, the ciphertext encrypted is likely to arouse the attention or cracking enthusiasm of the illegal authorized. Digital watermarking technology is one of the frontier international academic fields in recent years, related with information security closely. Digital watermarking technology does this by embedding the information--watermark in the vector object to certify the copyright or track the dealing of infringement. In this way, digital watermarking technology has been developed rapidly in copyright protection and integrity of certification of multimedia information as a supplementary of encryption technology.Currently, the main problems in the field of digital watermarking is how to secure copyright protection, and how to improve the robustness of digital watermarking in various attacks by querying and reading a large number of relevant documents and data. In this paper, the study is mainly based on the digital watermarking of Fourier transform algorithm to research the digital watermarking algorithm based on chaos and discrete fractional Fourier Transform intended to enhance the security and robustness of the digital watermark system. The article firstly summarized the transform watermarking algorithms and chaos theory systematically, discussed the chaos of scrambling the watermark, and researched the discrete fractional Fourier transform algorithm for digital watermarking in-depth. And then integrated chaotic sequence and the discrete fractional Fourier transform features, designed to contain copyright information of a binary image to be embedded as a watermark, and then embedded into the image phase components in order to achieve the security of the watermark hidden. The watermark extraction algorithm does not need to provide original image. Finally, based on MATLAB environment, the paper programmed and brought about the algorithm. After finishing my induction and consideration, following is the main the completion:(1) Briefly introduced the concepts of digital watermarking technology, chaos theory, chaotic system and how to apply digital watermarking system in chaos.(2) Introduced the transform domain watermarking algorithm theory in detail, discrete fractional Fourier transform advantages, and detailed description of the discrete Fourier transform algorithm-decomposition discretization algorithm.(3) In this paper, a digital watermarking algorithm is proposed based on chaos and discrete fractional Fourier transform. Design a binary image as a watermark, and encrypt it by a chaotic map under the control of the secret key. The original digital image is fractional Fourier transformed with the chaotic sequences generated by the key, and the watermark is embedded in the phase spectrum coefficient. The experimental results show that the algorithm is simple, invisible, and robust against crop, compression, added noise and rotation.