The Algorithm Of Digital Watermark Technology On Image Authentication

The revolution of digital technology has increased the ease of manipulation, reproduction and distribution of digital media; meanwhile, it also leads to potential security problems. Digital watermarking is an important technique to verify the authenticity and integrity of digital images through embedding secret data-watermark in the original data, thus it can protect the digital product from pirate and tamper. In the paper, the main work is as follows:At first, authentication watermarking technology is roughly described.Throughout the analysis on the existing authentication watermarking schemes, the crucial shortcoming inhered in the current schemes can be concluded as follows:accuracy localization and high security cannot be hold at the same time. In order to resolve this problem, a new watermarking algorithm based on chaotic mapping is presented. In this scheme, for the sake of improving the accuracy of localization, the image block's watermark is generated from the block itself, using chaotic system,the Logistic mapping to generate chaotic sequence for embedding the watermark; in order to enhance the security arid resist against collage attack completely, the block's watermark information is embedded into LSB plane of another image block with Torus Automorphism mapping and the secret key; so as to establish the correlation among the image blocks. Experiments are done by Matlab, the results show that watermarked images obtained have good subjective quality, precise localization of tampered areas; the algorithm is simple and safe, and the experiment results illustrate that it is validity.