Frequency modulation of printed gratings as a protection against copying

Sybrand Spannenburg

doi:10.1117/12.47113

1 October 1991 Frequency modulation of printed gratings as a protection against copying

Sybrand Spannenburg

Proceedings Volume 1509, Holographic Optical Security Systems; (1991) https://doi.org/10.1117/12.47113
Event: ECO4 (The Hague '91), 1991, The Hague, Netherlands

Abstract

A method for generating half-tone images on binary (i.e., paper and ink) systems using different (frequency-) modulation techniques is described. Security gratings and patterns are designed to generate 'alias' images or detectable codes, due to undersampling by the digital scanner.

Citation Download Citation

Sybrand Spannenburg "Frequency modulation of printed gratings as a protection against copying", Proc. SPIE 1509, Holographic Optical Security Systems, (1 October 1991); https://doi.org/10.1117/12.47113

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