The Research And Application Of The Semi-fragile Digital Watermarking

Fragile watermarking has been proposed recently as a focus to authenticate multimedia data by hiding a secret watermark into it. Several fragile watermarking schemes have been designed, but most of them are fail to meet the requirements of practical applications. From the point of view of image authentication, we will discuss the framework of fragile watermarking and its basic theory based on DCT and human visual system (HVS). Effective fragile watermarking schemes and a multimedia authentication system will be proposed.Against the basic characteristics of semi-fragile watermarking, such as the perceived nature of security, a certain robustness, and it can reliably detect altered, and in accordance with specific occasions in different places with different robustness features. The paper focused on the basic ideas of semi-fragile watermarking, watermarking information processing, the embedded of watermarking, extraction of watermarking and certification. Issues designed and realizated a highly efficient semi-fragile digital watermarking system operating on personal computer.The main contributions of the paper are as follows: analyzed the principles of digital watermarks and semi-fragile digital watermarking according to its features;an watermarking program embedded in middle frequency DCT coefficient were completed through a friendly graphical interface, based on discrete cosine transformation used by JEPG compression standards and the human visual system, and it keep the high similarity between the original image and watermarking image;fragile watermarking are designed to have compressed resisted capacity, particularly JPEG decompression to meet the practical requirements of the authentication techniques;the watermarking system have good presentation function on the images tailoring and replacing, achieved images safety certification.The success of this system development can effectively achieve images information integrity certification. The embedded system designed with strong resistance in JPEG compressed, thus enabling the need for compressed image processing product safety certification possible, and therefore greatly increase the relevance of fragile watermarking.