Generation And Encryption Algorithm Of Holographic Digital Watermarking For Security Printing

Commodity economy is highly competitive, and the counterfeit orinferior commodity has been a common scourge to the community. Anti-counterfeiting technology products are continuous increasing. It is evenmore important to stop fake commodities with scientific andtechnological progress and upgrades. Digital watermarking, effectivelyguaranteeing the copyright of data medium, conforms to comprehensiveproperty requirements of anti-counterfeiting technology, such as difficultto copy, low-cost, non-pollution. It has a wide field of applicationprospect in anti-counterfeiting packaging. However, printing is a multi-source heterogeneous attack to printing image. The watermarking can notbe extracted because of the distortion due to the digitizing process ofprintings. With a unique characteristic of not being tore up, hologram caneffectively resist the cropping and rotating attack. For this reason, thispaper combines digital image watermarking with holographic technique,to enhance the decoding difficulty of product security information and theability to resist various types of attacks in the printing process.Firstly, this paper discussed the computerized algorithm by which acommon digital image could be converted to a computer-generatedhologram (CGH). The three kinds of CGH, including Lohmann-CGH,Fourier-CGH and Fresnel-CGH, have been studied particularly abouttheir generation and reconstruction of the algorithm. For example, thesimulation that Fourier-CGH was cropped and rotated was done, and theresult verified the excellent robustness.Digital watermarking encryption algorithm based on hologram isstudied for characteristics of the printing and plate-making technology.According to the principle of the printing in CMYK color space, a novelhologram digital watermarking technique in DWT domain was presented.Fresnel hologram was used as an encrypted watermark, and then it wassecondly encrypted by Arnold transformation. The encrypted hologramwatermarking was embedded into the domain based on Bresenhamalgorithm, and the circle radius was used as embedding key to achieve the third encryption for watermarking. So the security of anti-counterfeitinginformation was effectively improved.Finally, the robustness of the designed hologram digitalwatermarking algorithm was test by computer simulating attacks. Theresults showed that this algorithm had a poor robustness for attacks, suchas filtering, reducing and printing screening, but it had an excellentrobustness for adding noise, exposure, cropping, enlarging, compressionand doodling.The security application of hologram digital watermarkingtechnology in packages printing anti-counterfeiting was valuablyexplored in this paper, and the achievement of this paper will serve asfirm foundation for the further research work.