Research On Image Semi-fragile Watermarking Technique In The Transform Domain

Digital watermarking has recently been proposed as a new mean to providecopyright protection of multimedia data and still image authentication. DiscreteCosine Transform and Wavelets are respectively the key technique in the subsistentsource compression coding standard JPEG and source compression codingstandard JPEG-2000, the background, the concept, the general framework and theresearch trend of authentication watermarking (known as fragile watermarking andsemi-fragile watermarking) technology is roughly described, the emphasis is on theanalysis of authentication watermarking classified by the spatial and the transformdomain, also their advantages and disadvantages are analyzed, in addition, commonattacks applied to authentication watermarking are summaried. Two novel semi-fragile watermarking algorithms based on DCT-DWT domain combining areproposed separately in this paper, both algorithms generate the watermarks in theDCT domain and embed the watermarks into the original image in the DWT domainby using private chaos keys which are designed to define watermarks to be embeddedand determine the position for watermarking. Both algorithms can renew thewatermarking completely without original image. Experimental results show that theproposed algorithms are robust against JPEG compression, and provide very goodclassification of intentional and incidental tampering. We can know that what mostly characterize the algorithms presented in this paperare security and practicality. It's also suggested that the research on multimedia dataauthentication should aim at concrete situation. It's undoubtedly that designing thewatermark scheme based on semi-fragile watermarking and cryptology should bepromising.