Research On The Acquisition And Recognition Technology Of Holographic Watermarked Anti-counterfeiting Printing Information

The holographic watermarking has advantages of "difficult to copy, easy to discriminate, low cost, zero pollution", therefore be applied in the field of anti-counterfeiting printing. To research the acquisition and recognition technology of holographic watermarked anti-counterfeiting printing information play a key role on perfecting the anti-counterfeiting system based on the holographic watermark. This study analyzed the main cause of deterioration of watermark extraction images’ quality in the acquisition process, and proposed printing image rotating and trapezoidal distortion resistant holographic watermarking security program. Two kinds of acquisition methods, scanning and shooting, were studied, and performed the extracted watermark information preprocessing before recognition. Extracted watermarks have better quality to meet the demand of recognition after rotation, trapezoidal distortion resistance and recognition pretreatment. The main research work are as follows:Firstly, based on the characteristics of the holographic watermarking, offset printing process, and the substrates material surface, this paper designed the watermark extraction method of CMYK-RGB-GRAY model to solve the problem of watermark information were transferred in the process of embeded and extraction based on single channel. In addition, print materials characterization analysis of the peak signal to noise ratio(PSNR) and LAB color measurement were preformed for host image and anti-counterfeiting image. The results showed that the properties of printing quality is well, the invisibility of original watermark and color difference of security image are up to the application standard.Secondly, based on the holographic watermark security system, this paper designed the acquisition and recognition processes of printed watermark information and analysed the basic principle of the scanner and digital camera image acquisition to put forward the Radon rotation correction and methods of extracting watermark from the trapezoidal distortion micro-deformation area. Using normalized correlation coefficient(NC) to evaluate simulation and printing experiment extracted watermarks. The results showed that the greater the original watermark information, the worse the quality of extracting watermark from the same size of the host image. GRAY mode print holographic watermark anticounterfeiting image has better quality of extracted watermark than CMYK mode. Different rotation angle has little impact on the quality of the extracted watermark, extrated watermarks can satisfy the identification requirements after rotating correction and pretreatment before recognition. The trapezoidal distortion micro-deformation area can extract watermarks with better quality.Finally, in view of the binary digital watermark and gray image watermark has designed a set of identification pretreatment program that Levels adjustment, images enhancement, filtering denoising, images binarization. Verified the feasibility of all solutions by the cover printing anti-counterfeiting example.