The Study Of Authentication Technology Of Image Contents Based On Digital Watermarking

With the continuously perfect extension of the computer network and the quick development of multi-media information processing technology, we can create, save, edit and spread the numerical multi-media information conveniently. However, the development of technique also brings the problem of how to guarantee the safety of information. So it becomes an urgent problem of identifying authentication and carrying out integrated protection for multi-media information.The thesis mainly studies the application of the digital watermarking in the picture contents authentication technique.It analyzes the basic principle of the digital watermarking technique and the key problem of picture contents authentication technique, and analyzes the current typical algorithms ways home and abroad from different angles, and then proposes two kinds of digital watermarking projects of the digital image contents selectivity attestation and exact attestation on this foundation:The former puts forward a kind of semi-fragile algorithms with certain practical worth through combining the basic thought of Spread-Spectrum modulate technique and discrete wavelet transformation, and then modulates and encrypts water mark data and embeds them into the DWT low frequency coefficient. It carries out the blind detection and tampers localization, and can distinguish the valid distinction malice and non- malice's distort availably;The latter analyzes the principle of the genetic algorithms and lifting wavelet transformation, and proposes a new fragile algorithm based on genetic algorithm. It applies the genetic algorithms in finding the frequency band to keep embedded data having a balance between the invisibility and robustness, at the same time, achieving tamper detection and tamper localization.Last, the thesis carries out a summary of the possible research direction of digital watermarking technique and points out further academic direction. The semi-fragile and fragile digital watermarking algorithms of the thesis have been applied in the matlab7.0 platform, which was validated by experimental results and proved to be satisfactory.