Automated Optimization of Void Pantograph Settings
Abstract:Void pantographs (VPs) have been an important part of the security printing toolkit for several decades. When crafted for a specific 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 historically been designed only for a specific printing technology, and so cannot be extended to a mobile-printing world, where the VP needs to be supported by a wide range of printers.
In this paper, we describe an automated process for optimizing the VP settings. These are the background and foreground pattern used in the VP—the background “disappears” when copied and the foreground “bolds”. VP test sheets are created using the ranges of background and foreground settings necessary to guarantee identification of at least one “readable” pair of settings. This can be automated by writing the VP as a readable mark—for example, a barcode that can be read (or not read) by a barcode reader; text that can be read (or not read) by an optical character recognition (OCR) engine; or even a face that can be recognized by a face recognition engine. The successful VPs will not be readable (using camera images to prevent a “copying” effect) when originally printed but accurately readable (using a camera) after a single copy, or print-scan, cycle.
Document Type: Research Article
Publication date: January 1, 2011
For more than 25 years, NIP has been the leading forum for discussion of advances and new directions in non-impact and digital printing technologies. A comprehensive, industry-wide conference, this meeting includes all aspects of the hardware, materials, software, images, and applications associated with digital printing systems, including drop-on-demand ink jet, wide format ink jet, desktop and continuous ink jet, toner-based electrophotographic printers, production digital printing systems, and thermal printing systems, as well as the engineering capability, optimization, and science involved in these fields.
Since 2005, NIP has been held in conjunction with the Digital Fabrication Conference.
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