Research On Image Fragile Digital Watermarking

Fragile digital watermarking technology provides effective solutions for multimediacontent authentication and tamper-detection. Unlike the traditional digital signature that mustbe bounded to the transmitted date, a watermark is embedded directly in the multimedia date.Many important applications could benefit from the use of fragile watermarks. So it is aresearch hot-spot in recent years. This thesis does research on fragile digital watermarking forimage authentication.This thesis analyses the technical characteristics of fragile watermarking, and then givesan overview of the current fragile watermarking algorithms for image authentication. Thedetailed descriptions and experiments of four typical algorithms such as Wong algorithm,Y-M algorithm, L-C algorithm and Kundur algorithm are given in this dissertation. A novelfragile watermarking algorithm based on binary look-up-table (LUT) and Hash value in thediscrete wavelet domain is proposed to overcome the security problems of block-wiseindependence watermarking schemes. Owe the space-frequency characteristic and thelocalization characteristic of the wavelet transform, the algorithm embeds a markingwatermark in the LL sub-band with the look-up-table method, which can be used to detectand localize common tampers. The algorithm choose the Hash value of the HL sub-band orthe LH sub-band as another watermark, which is embedded in HH sub-band for resisting thecounterfeiting attacks like VQ attack, Collage attack and so on. This paper also compares thefragile performance of the four typical algorithms and the proposed algorithm on experimentsin terms of their reliability, security, perception and the feature of detecting tempers. Thetheoretical analysis and the experimental results all demonstrate that the proposed algorithmhas both the effectiveness in resisting possible attacks and good ability of detecting localalterations. It is a kind of secure, effective and reliable fragile watermark algorithm.This thesis also summarizes the watermarking application status, and especially presentsa program design for the content authentication of important financial document. Apply theHash function and the least significant bit digital watermarking algorithm on the image of financial document to realize the content authentication of the financial document.