Study On Image Authentication Techniques Based On Semi-fragile Watermarking

Semi-fragile authentication watermarking technology as a new reliability protection watermarking technology of the imge authentication has aroused the worldwide scholars' attention to investigate. Nowadays, aiming at semi-fragile watermarking technology, a lot of research schemes are presented, but it is rare to put into practical use. The digital watermarking technology, especially the basic principle, supporting theory, and relative technology of the semi-fragile watermarking authentication technology are studied systematically in this paper. Afterwards, the paper designs and implements an image authentication system of adaptive semi-fragile digital watermarking based on the wavelet energy.The main contributions are as follows:1. Aiming at the problems of the watermark information security in the authentication technology, this paper designs and improves an scrambling algorithm based on the image block reconstruction technology and analyses and compares the algorithm from the time, space and the infinitude aspect, etc.2. It suggests a new assessment criteria formula for assessing scrambling effect. It provides the evaluation background of how to influence the scrambling effect by analyzing the correlative scrambling parameter through adopting the four patterns to scale the admixture and the uniformity, such as the mean in the block of the block unit, the standard deviation, and the mean between blocks scrambling deviation, the mean between blocks, and the four-mixed mean standard deviation.3. The paper designs an image authentication algorithm of the adaptive semi-fragile digital the watermarking based on the wavelet energy. The author makes use of the character of the wavelet trees in the wavelet domain to define its energy function to constitute the watermark. In the process of authentication, the tamper assessment of function is presented, and the ability to tamper authentication of the algorithm's influence on the watermark information is enhanced. Moreover, the paper makes a theoretical analysis and experimental testing completely and particularly from the aspect of the complexity, the relevant parameters, the quantization error and attack resist.4. Taking advantage of the Matlab software platform, the paper designs and implements an image authentication system of adaptive semi-fragile digital watermarking based on the wavelet energy.In conclusion the paper sums up the work, suggests the correlation prospect of the development of the authentication watermarking technology as well, and points out the further needs of research.