Boundary processing on the watermark with hybrid halftone dots

With the flourishing development of computer technology, image duplication can be carried out in a convenient way. In order to protect intellectual property rights, experts are devoted to many anti-counterfeiting technologies. Among them, watermark by hybrid halftone dots is formed by amplitude modulation (AM) dots and frequency modulation (FM) dots. Because of different halftone dots, watermark can be observed by closer look. In this study, we design a boundary processing to make the edge area of two dots gradual change. Then, the visibility is evaluated by Human Visual System (HVS). Results shows the boundary processing can effectively hide watermark, and it can be applied to many document security applications.