Variable Data Void Pantographs

[摘要] Void pantographs (VPs) have been an important part of the security printing toolkit for several decades. When precisely designed for a given printing technology, VPs provide an almost "magical" effect*they are nearly invisible in the original print and then stand out strikingly when they are copied. However, this effect comes at an expense*VPs have traditionally contained static content and so are usually fine-tuned for flexo, gravure, offset or screen printing.In this paper, we extend variable data printing to VPs. First, we obtain optimal VP settings (background and foreground pattern*the background "disappears" when copied and the foreground "bolds" for the printer/copier pair). Next, we create a database of images for which we wish to create variable VPs (e.g. serialized numbers, individual labels, location-specific messages or images, etc.). We then apply an image filter to these images. Our most effective filters to date have been the edge- filter and the entropy-filter, both of which create a VP foreground where the information content of the image is high. For logos, using a chroma-filter is also often effective. Next, the individual VPs are written to the individual print elements (label, page, etc.) for which they are intended. The variable data message is now what "pops up" when the item is copied.

[发布机构] HP Development Company

[学科分类] 计算机科学（综合）

[关键词] Copy Evidence;Covert Printing;Image Analysis;VDP