A Hybrid SVD-DCT Watermarking Method Used for Halftone Image

In this letter, a digital watermarking method which combines the singular value decomposition (SVD) and the discrete cosine transform (DCT) is presented. First of all, The Arnold scrambling and the DCT are performed on the watermark and the original image, respectively. The SVD transform is performed on the image when scrambled watermark is embedded, then the watermarked image is formed. Finally, we extract watermark from the image which is handled by halftone screens. The experimental results show that this method can achieve the highest possible robustness without losing the transparency. Also it can anti printing and scanning. All the processes do not require any additional equipment. It will bring new hope to the field of anti-counterfeiting printing with singular value decomposition is applied to the half-tone image area.

Study of Anti-Counterfeit Printing with Cylindrical Lens Sheet Basic on Screening Copy

Grating material can have security effects in print for its specific optical properties. In this paper, the technology of copyright protection used in Screening Copy is studied basic on the optical properties of cylindrical lens sheet and screening. Firstly, the relation of the parameter of cylindrical lens sheet and the parameters of half-tone image is studied. Achieving the arithmetic what used to set dot basic on the relation. Secondly, imitating the experiment in Photoshop cs2 and setting dot after transferring the image to halftone use the screening of it. Meanwhile, generate the layer which has the effect of cylindrical lens sheet and can get the imitate effect while rotate the layer. In the experiment, using the printer of Epson 7880 to print the image and examining the security through corresponding cylindrical lens sheet. The experiment proves the hidden information only can be seen though cylindrical lens sheet and it shows the anti-counterfeit way have well effect in screening copy. And the equipment and processes are not needed too much for this way, so the anti-counterfeit effect can be achieved in the condition of not adding cost.