Citation: Grši´c, J.Ž.; Jureˇci´c, D.;
Golubi´c, L.T.; Žiljak, V. Hidden
Information in Uniform Design for
Visual and Near-Infrared Spectrum
and for Inkjet Printing of Clothing on
Canvas to Enhance Urban Security.
Appl. Sci. 2022, 12, 2152. https://
doi.org/10.3390/app12042152
Academic Editors: Arkadiusz Gola,
Izabela Nielsen and Patrik Grznár
Received: 9 September 2021
Accepted: 14 February 2022
Published: 18 February 2022
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Article
Hidden Information in Uniform Design for Visual and
Near-Infrared Spectrum and for Inkjet Printing of Clothing on
Canvas to Enhance Urban Security
Jana Žiljak Grši´c
1
, Denis Jureˇci´c
2
, Lidija Tepeš Golubi´c
1,
* and Vilko Žiljak
1
1
Department of Informatics & Computing, Zagreb University of Applied Sciences, 10000 Zagreb, Croatia;
jana@tvz.hr (J.Ž.G.); vilko.ziljak@tvz.hr (V.Ž.)
2
Faculty of Graphic Arts, University of Zagreb, 10000 Zagreb, Croatia; djurecic@grf.hr
* Correspondence: ltepes2@tvz.hr; Tel.: +385-98-380956
Abstract:
In this paper, we publish the algorithm to create a dual image manifested in the infrared and
visible spectrum. To distinguish the information in the two light spectra, twin dyes are introduced
for the inkjet plotter and printing realization for garment and canvas items. The graphics, invisible to
the naked eye, are designed for the near infrared (NIR) spectrum and are suitable for urban security
where surveillance cameras with IR detectors are installed. The duality of dyes is presented in tables,
and the analysis is a basis for programming and developing new algorithms for the application
of “Infrared Dyeing” on different materials and printing technologies. Through spectroscopy, this
innovative solution demonstrates twin colorants by printing in one pass through the plotter such that
one image remains visible, while the other one is hidden to the bare eye. The uniform and the school
bag cover presented in this paper are kept simple in design because they incorporate information
hidden to the naked eye but visible with surveillance cameras and all the other infrared detectors.
The article provides mathematical models of duality coloring as a basis for programming the graphic
prepress that merges both of the images, the visual one and the infrared one. A topic is the fusion
of two images with colors that represent two graphs, with independent contents for the visual and
near-infrared spectrum.
Keywords:
personal safety; urban security; dual surveillance cameras; twin colors; NIR spectroscopy
1. Introduction
The digital technology of hidden data in uniform design extends from the visual
to near-infrared spectrum. The software solution in INFRAREDESIGN
®
technology of
merging two images was preceded by the study of twin colors for textile material [
1
]. By
spectroscopy of dyes and pigments, we obtained accurate results about the properties of
each colorant in two spectral states: visual and infrared. In digital inkjet printing, our
new enhanced GCR method (gray component replacement) was introduced to provide
separate color matching for the visual and NIR spectra [
2
,
3
]. The enhanced near-infrared
(NIR) information is embedded in the existing visual design, which remains in its initial
form. The garment is given a dual detection state, separated by two spectral regions:
visual and near-infrared. The formulations for the dual twin colors are presented by using
spectroscopy in the extended light range from 750 to 1000 nm [4].
The idea of applying infrared (IRD) printing on clothing contributes to the develop-
ment of a new generation of uniforms and camouflage cover for target groups [
1
]. Infrared
printing on clothing and garments is performed with screen printing or conventional ink-jet
inks. The novelty in the IRD algorithm with which it is planned to provoke dual design
and their appearance separately in the visual and infrared spectrum does not depend on
the height of the edition, i.e., on the number of copies of such clothing.
Appl. Sci. 2022, 12, 2152. https://doi.org/10.3390/app12042152 https://www.mdpi.com/journal/applsci
