Research On Semi-Fregile Watermark Using PSO

Digital watermarking technique is a whole new mean to guard information security. It has been a strong method for copyright protection and authentication on multimedia And it involves the theory on communication and information, digital image processing, network security and so on. It is of high academic value and economic value.Semi-fragile watermarking technique is an important branch of digital watermarking .It can tolerate general signal processing, detect any spiteful tamper on marked multimedia data, locate spatial regions within an altered image, and even can estimate what kind of modification had occurred and recover the tampered data With these attractive characteristics, semi-fragile watermarking has become a research hotspot of multimedia .authentication domain in recent yearsThis paper compares information hiding with digital watermarking and modern authentication—three ways for information security, reviews the basic theory on digital watermarking, gives an analysis on present researches on digital watermarking techniques, a semi-fragile watermarking in DCT area based on PSO,was proposed in this paper, using the PSO to find the best place to embed the watermarking ,not only improved the PSNR,but also enhance the security . In DWT area ,using the PSO as a quantity step to find the best quantity matraix .that can enhance the robustness resist the JPEG compress .and improved the PSO, the improved PSO, have a better robustness to defance the JPEG compress. The experimental results :the three method all have a localize the tamped,and credible practical.