Studies On Implications Of Watermark Technology In The Field Of Print-materials Security

At present, the copyright of printed materials, such as certificates, notes, trademarks and so on, has been becoming increasingly serious and has become an issue that has great impact on people's lives and social economic development. Although a variety of security technologies arise and to some degree they play a role in security, the issue can not effectively prevent. Digital watermarking technology sheds some light on the copyright protection issue. Compared to traditional security technology, digital watermarking has its unique advantages, such as invisibility, difficulties to counterfeit, the ability to be gradually upgraded, and low cost and so on. It is a new and challenging direction in fields of information security and has an important social significance.So far, studies for digital watermarking technology are relatively few, Arney established print-scan model which has nothing to do with halftone, Lin also established a good model of the print-scan, and both of them embedded digital watermark into the DFT frequency domain, but both of them need origin image to be corrected which makes it difficult to be applied and developed; Solanki studied attributes of the DFT coefficients in the process of print-scan; Dajun He make a good supplement to Solanki's conclusions by detecting image using different printers and scanners in different resolutions. Both of them embedded watermark information based on attributes of DFT coefficients in the process of print-scan by quantifying or sub-blocks,which has a greater watermark capacity and a higher correct rate of extraction; Anu proposed an algorithm to embedded watermark in the domain of DFT and Wavelet to robust to print-scan and it also has some robustness to JPEG compression; Lili obtained rotation invariant using DFT and LPM (Log-polar coordinate transformation) and embed digital watermark in the rotation invariant, but the short length of the digital watermark information is a problem to be resolved.In this paper, two vulnerable watermark algorithm based on the current studies is presented, which can be used in the field of print materials security because of its great robustness to genuine printed materials and fragile robustness to the piracy (second print-scan materials).In the end, in the paper two novel watermark systems auto-detected are designed and completed:one is based on the scanner and personal computer and the other based on the Davinci and camera.