## 5 Dye Spectroscopy in the Visual and Near-Infrared Spectrum  
In order to achieve a double image with inks in a plotter, additional information about dyes, their position in two zones of light is required. No special colors are needed for infrared images, but the properties of these dyes are important: the penetration of ink into the canvas, the consistency of the colorant tone of the dye over a longer period of use of the print [12,13]. Therefore, when talking about infrared design, the word color is replaced by the word dye, which means that it is possible that the same color of different mixtures has different properties. The specific dye response to the infrared spectrum is the key to the solution for creating infrared images. Process dyes are observed through their light absorption properties in the range of the visual and near-infrared spectra (400 to 900 nm). Spectrograms are performed with a Projectina device (PAG-24 blockade [11]). From Table 1, blue, olive, and red are presented. For precise determination of the C, M, Y, and K compounds of the dye, that is, to separate the information intended for the visual and NIR spectrum, spectroscopy is used. The amount of black component is the default. The adjustment of the twin components is intended for the range from 400 to 700 nm. In the range of 400 to 700 nm, all three dyes have the same spectral values and show the same color for our naked eye. The range from 700 to 800 nm (Z1) is the range of spectral divergence of absorption values for the same dye [4]. The red color is presented as twins with 20% coverage and with 40% carbon black. All three graphs (X\({}_{0}\), X\({}_{20}\), X\({}_{40}\)) match well in the visual spectrum, which is the initial task of color equality. Their separation starts at 700 nm and ends at three sizes: Z\({}_{20}\), Z\({}_{0}\) and Z\({}_{40}\). These three sizes manifest as different gray tones in Z camera images. The graph shows the absorptions of pure dye components: Y (52% and 66% coverage), magenta (50% and 86%) and cyan (57% coverage). Each of the process inks has its own domain of light absorption. Yellow has a maximum at 460 nm, magenta at 560 nm. Cyan ink has a wider domain with a maximum at 700 nm. Component graphs determine the domain of visibility (in our eye). Above 750 nm, inks C, M, and Y do not absorb light (Figures 5 and 6). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Measured Data: C, M, Y, for X\({}_{0}\), X\({}_{20}\), X\({}_{40}\)** & **L\({}^{*}\)a\({}^{*}\)b\({}^{*}\)** & **Color** \\  & **K = 0\%** & **K = 20\%** & **K = 40\%** & & \\ \hline
90, 90, 48 & 77, 71, 26 & 61, 49, 0 & 14, 30, \(-\)34 & 8 \\  & 30, 35, 89 & 18, 19, 76 & 3, 0, 61 & 66, \(-\)2, 62 & 9 \\  & 52, 97, 83 & 36, 80, 65 & 16, 60, 44 & 26, 54, 17 & 10 \\ olive & 55, 45, 95 & 43, 25, 81 & 29, 1, 63 & 52, \(-\)12, 48 & 11 \\ red & 57, 86, 66 & 42, 69, 52 & 25, 50, 25 & 31, 36, 6 & 12 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 5: Spectrograms of red color twins (12–Red 2). These process inks in printing are essential in understanding the programming of twin dyes combined with carbon black ink. Carbon black ink extends from 400 and further from 900 nm. Due to the effect, the transparency properties of the dye, the common graphic representation of the dye is not a mere summation of the light absorption of the individual components. Figure 6 shows two colors. Their absorption at 900 nm has common values, especially for 40% black carbon black color coverage and especially for 20% K dyes coverage. These values are the same for red color (Figure 6). In the first part of the visual spectrum (400 to 700 nm, marked V), the two graphs are sufficiently similar that the numerical value \(\Delta\)E satisfies the color equality criteria. The blue color has a maximum absorption at 700 nm. It is determined by the property of cyan dye. Other components do not absorb light in this area. After 700 nm, the twin dye graphs are separated (Z1).