Research And Achievement Of Watermark Algorithms Of Radar Image In VDR

The widespread adoption of digital imaging techniques has caused problems of illegal copy and tampers of the products,generated a requirement for authenticity verification and took more seriously.The watermark with a special function is embedded into the multimedia information to protect the copyright of the original author and authenticate the integrity and authenticity of the multi media information.The watermark technique has become one focus of researcher. The attention of dissertation is focused on semi-fragile watermark based on image attestation.The work is focused on the algorithm of radar image.In this dissertation,a semi-fragile watermark system,a watermark system for authenticity verification is analyzed and researched,and then an improved semi-fragile watermarking system based on the system is proposed.After compared with another algorithm,it is sure that the algorithm is suit to radar image authenticity.Firstly,a systematical introduction of the concept,characteristic origin, applications,classification,fragile watermark,semi-fragile watermark and background of information hiding is given first,then the principles of IAS are described with their characteristics and model algorithm and designing requirements and limitations,before the ways of performance evaluation,attacks and countermeasures are introduced.Frame class of proceeding of semi-fragile watermarking and algorithms mainly used are presented.Then,knowledge of Discrete Cosine Transform is expatiated.Thermos DCT and its fast algorithms are discussed,and compendious introduction of Discrete Wavelet Transform is given and the two methods,DCT and DWT are compared as well.The baseline of JPEG compression and some problem about JPEG relevance to watermark are introduced.After thorough analysis of digital watermark algorithm based on relation, implant location is modified.It is sensitive to modify,and modify implant order and fix location to cut.A semi-fragile watermarking algorithm for color images was presented,in which the watermark was embedded through the single channel.It can be used to radar image c which is in VDR(Voyage Data Recorder).This algorithm based upon relationship in DCT(discrete cosine transform),using binary image as the watermark and detection without prime image is improved and combines human vision system speciality.It can be sensitive to modification.Through lots of experiments,they shows that it's fragile to other kinds of attacks,it can orient 8~*8 block in the spatial domain.On the other hand,the algorithm has great robustness under some degree JPEG compression.Last,a design thought which watermark system combines MATLAB and VC++ was presented.A compiling.m file to C method was presented,which combines MATLAB and VC++ and uses powerful interface function of VC++ and fast computing of MATLAB.It accomplishes watermark embedding and distilling and a conveniently interface to show image.