engleski

Design of security graphics with infrared colours

The color tone defined in RGB, HSB and Lab systems may be defined through C0 M0 Y0 K0 seen by the human eye but invisible in IR wave lengths. This color tone may be associated with the Ci Mi Yi Ki more wider seen in wavelengths of the visible spectrum as well as in IR wavelengths. The Cm Mm Ym Km maximum possible response in the IR area is determined for every color. The double separation program uses two images. The first image is the one we see fully in the visible specter part. The second image is the pattern that has the role of a mask. The CMYK separation is controlled with the pattern in order to achieve the appearance and elimination of the first image's visibility in the IR area. The image element covering capacity values of the second image most often equals to zero or to the maximum covering capacity value. All covering capacity values that fall into the area between the two listed extremes enable visibility gradation control in the IR specter. Each single color tone has its own gradient values for CMY components depending on the K component increase. Each components SC, SM and SY gradient depends on the C0, M0 and Y0 values that compose the observed color. The paper contains the gradient coefficient matrix with three independent variables for each color. The parameter values are proven by linear regression and on basis of print measuring. The once determined gradient parameters for the observed printing technique and the corresponding process colors provide unlimited application of IR control in colored images by using only process toners.

security graphics; infrared colours; graphical design

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