摘要：This paper deals with the application of new steganographic methods in postage stamp printing technology with the goal of securing them against counterfeiting.Postage stamp designs are presented which contain double information in the visible and in the infrared spectrum area.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 optimal regression model developed on the basis of colour tone measuring for the visual and infrared spectrum.A technological procedure has been elaborated for producing and printing based on 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.
