engleski

New postage stamp design with tone gradation in Infraredesign technology

This paper is about applying new steganographic methods in postage stamp printing technology with the goal to secure them against counterfeiting. Postage stamp designs are offered, containing double information in the visible and in the infrared spectrum area. The new methods include printing with process printing inks that have a continuous response in the infrared area of the spectrum. The infrared Z image cannot be produced with conventional CMYK separation in such a way that the hidden picture does not show through when looking at the print. This is the reason for introducing CMYKIR separation, with mathematical relations that respect printing ink characteristics in the RGB to CMYKIR system conversion. A mathematical model with targeted separation characteristics is proposed, with seven independent variables. It has been created as the result of an optimal regression model on basis of color tone measuring for the visual and infrared spectrum. A technological procedure has been elaborated for producing and printing on the basis of such designs. It is possible to detect the infrared image with the help of a device – the infrared ZRGB camera. Counterfeiting is impossible due to the irreversible conversion of the CMYKIR separation into the RGB system applied in contemporary scanners or cameras.

postage stamp; double image; CMYKIR; Infrared technology; Z parameter

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