Importance

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Abstract

Due to the wide availability of photocopiers, scanners and printers, security documents are more and more subject to counterfeiting attempts. The present disclosure describes security documents incorporating a new security feature based on a microstructure, whose shapes vary according to intensity and color, as well as methods and computing systems for synthesizing such security documents. The microstructure may be composed of text, graphic elements and symbols. Since the security document is built on top of the microstructure, document elements such as text, graphics and images as well as microstructure elements cannot be erased or modified without introducing visible discontinuities in the security document. Furthermore, thanks to transformations having the effect of warping the microstructure into different orientations and sizes across the security document, individual microstructure elements cannot be simply copied and inserted elsewhere. The present invention also discloses how a high-quality microstructure may be automatically generated from microstructure shapes (e.g. a bitmap incorporating these shapes). The security document synthesized with the resulting microstructure makes the chosen microstructure shapes visible over nearly all the image intensity range. Security documents incorporating a microstructure may be synthesized with standard, non-standard and special inks, where one, several or all contributing inks are part of the microstructure. Considered inks are for example metallic, iridescent, fluorescent, phosphorescent and ultra-violet inks. Thanks to special inks, parts of the security document conveying a message or parts of the security document's microstructure are hidden under specific observation conditions and visible under other observation conditions (illumination, viewing angle, etc. . . . ).

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First Claim