March–April 2017


Gorazd Golob

EDITOR-IN-CHIEF

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1-17

 

Quality control of embossed holograms by measuring gloss and color values

Pauline Brumm1, Edgar Dörsam1, Duy Linh Nguyen1 and Martin Schmitt-Lewen2
E-mails: pauline.brumm@stud.tu-darmstadt.de; doersam@idd.tu-darmstadt.de; martin.schmitt-lewen@heidelberg.com
1 Technische Universität Darmstadt,  Institute of Printing Science and Technology,  Magdalenenstr. 2, 64289 Darmstadt, Germany
2 Heidelberger Druckmaschinen AG,  Alte Eppelheimer Str. 26, 69115 Heidelberg, Germany

Abstract

Embossed holograms are increasingly often used for the decorative refinement of printed products. So far, there has not been much scientific research about quality control of embossed holograms as well as research about the influence of the background color on the quality of embossed holograms. For this purpose, hologram samples with different background colors were produced in a manual experiment, using the principle of UV embossing. At first, the quality of the samples was evaluated through a visual experiment. The conceptual design of that experiment was part of this research. Second, gloss and color values were measured with conventional hand-held measuring instruments used by the graphics industry. Color measurements were conducted with an X-Rite MA98 multi-angle spectrophotometer and measurements of gloss values with a BYK micro-TRI-gloss gloss meter. The comparison of the results of the visual experiment and the color measurement led to the conclusion that conventional color measuring instruments can eval- uate the influence of the background color on the quality of embossed holograms. It was found out that calculating the color difference ∆E*ab between background color and sample can be used to recreate the results of the visual experiment, whereas the samples’ chroma C*ab is not suitable for evaluating the influence of the background color. The number of provided measuring geometries is a limitation of this approach. Moreover, the comparison of the results of the visual experiment and the gloss measurements showed that conventional gloss meters cannot evaluate the influence of the background color. However, conclusions concerning the UV embossing process can be drawn from a sample’s gloss. This suggests the usage of gloss measurement for process control.

Keywords: micro embossing, UV curing, visual experiment, nickel shim, multi-angle color measurements

JPMTR 092 | 1701 Research paper
DOI 10.14622/JPMTR-1701
UDC 005.6:778.38-023.7/535.6

Received: 2017-01-23
Accepted: 2017-03-16

Print quality and color accuracy of spectral and colorimetric reproduction

Radovan Slavuj1,2, Ludovic G. Coppel1,3, Irina Ciortan1, Peter Nussbaum1 and Jon Yngve Hardeberg1
E-mails: slavujr@gmail.com; ludovic.coppel@gmail.com; irina.ciortan@gmail.com; peter.nussbaum@hig.no; jon.hardeberg@hig.no
1 The Norwegian Colour and Visual Computing Laboratory, Teknologiveien 22, 2802 Gjøvik, Norway
2 Radovan Slavuj, Pavla Micunovica 9, 24300 Backa Topola, Serbia
3 Ludovic G. Coppel, Bolindervägen 79, SE-17674, Järfälla, Sweden

Abstract

When reproducing an image by means of printing, the most common concerns are to have good colors and the least perceivable artefacts. These two concerns are most conveniently conveyed via two common reproduction goals: color accuracy and image quality. The goal of this paper is to evaluate how color accuracy aim relates to printed image qual- ity, the attribute usually tight to the method of halftoning. In order to provide a relation between these two different goals, spectral and colorimetric color management workflows are paired with different halftoning methods. Image quality metrics is employed both on the output from the color separation process and on the print output. Overall, spectral reproduction used in this paper showed higher color accuracy but lower image and print quality score, even if combined with state of the art halftoning methods.

Keywords: reproduction workflow, halftoning, image quality, spectral reproduction, multichannel printing

JPMTR 093 | 1509 Research paper
DOI 10.14622/JPMTR-1509
UDC 655.1-021.465:535.3:774.8

Received: 2015-11-19
Accepted: 2017-04-29

Analysis of UV varnish for textured effect

Shrikant Tora1, Sanjay Sharma2 and Pratik Borude3
E-mails: shrikant.tora@yahoo.com; sanjay_shm@yahoo.com; pratik.borude.1994@gmail.com
1 14/110, Gandhi Nagar, Akkalkoat Road, Solapur, Maharashtra, India-413006
2 Jabalpur, MP, India-482001
3 Pune, Maharashtra, India-411009

Abstract

Packaging and especially printing industry is experiencing an exponential growth in terms of customer demands. Owing to these demands, UV varnish is playing a major role, which is preferred over lamination due to environmental issues and cost. The UV varnish can give gloss or matte finish. Textured effect on the surface can be achieved by blend- ing gloss finish over matte. Various textures can be achieved by varying the blend of solutions, ratio, viscosity, surface tension, etc. Among varnishing parameters that affect the results are UV-lamp intensity, speed of varnishing and screen ruling of anilox cylinder. The texture created in such a manner, needs to be evaluated with respect to the topographic index to find an optimum combination of the parameters to achieve a particular textured pattern.

Keywords: surface finish, topographic index, offset printing, coating process parameter, image analysis

JPMTR 094 | 1615 Research paper
DOI 10.14622/JPMTR-1615
UDC 667.6-023.731 | 535-3

Received: 2016-12-03
Accepted: 2017-03-02