| Nowadays the multimedia technology and the Internet are developing rapidly. Information security of digital media and the protection of information property right and authentication are becoming more and more pressing and have become a very hot and important topic of discussion. Digital watermarking technology is one of the newest methods of digital production copyright protection, but the ability of the digital watermark arithmetic is not enough suitable for resisting many attacks. How to improve the robust of the watermark arithmetic is becoming the key problem to be solved.In this paper, the fundamental concept, general model, classic algorithm, research situation and development direction of watermark are introduced firstly. And then analyze the characteristic and disadvantage of the watermark arithmetic. By the researching of the spread spectrum in communications and the wavelet in image transacting, a new watermark algorithm based on the spread spectrum and the wavelet transform is proposed. The main purpose of this algorithm is to improve the robust of the watermark system. Base on this algorithm, an image watermark system is designed. And do some test to testing the practicability of the system. In this algorithm a disordered bi-level image which was spread by the Gold spread spectrum is embedded into the images which were transacted by three-level wavelet transform. And in the course of embedding, the watermark is embedded into the important coefficients of intermediate frequency using the idea of the Embedded Zero-tree Wavelet Code for reference and according to the character of the HVS. In the detecting, the watermark can be distilled using the key only.Experiments proves that this algorithm both improve the stability of the system and achieve well clarity. Compared with the other spread spectrum algorithm, this one is more robust against the typical image processing attacks such as adding noise, filtering and JPEG compression. |
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