Department of Graphic Arts & Communications, College of Technology, National Taiwan Normal University, Taipei 10610, Taiwan, R.O.C.
The objective of this research is to use modied digital halftoning techniques of Amplitude Modulation (AM) and Frequency Modulation (FM) to integrate lenticular lenses with switching images and embedded infrared watermarks. Modied digital halftoning techniques have been used to compose animated graphics and the infrared watermark. The infrared watermark consists of varied combinations of AM/FM or FM/FM halftone dots in black/cyan, magenta and yellow inks. Since the carbon material in black ink can absorb infrared light, the hidden watermark becomes visible under infrared detection. Using a lenticular lens, the image-switching eect can be achieved by viewing from dierent orientations. The results show that FM/FM halftone dots have a better performance in implementing a lenticular display with both image-switching features and hidden watermarks that can be observed under infrared light. The technique developed in this research can provide value-added applications for anti-forgery and product protection