June 2021

Download the full issue: 2-21

View the letter from the Editor

Gorazd Golob

Editor-in-chief

The news section of the Journal: Topicalities

Click on titles to download full articles:

Ink splitting in gravure printing: localization of the transition from dots to fingers 

Pauline Brumm1,2, Tim Eike Weber1, Hans Martin Sauer1,2 and Edgar Dörsam1,2

E-mails: brumm@idd.tu-darmstadt.de; timweber@idd.tu-darmstadt.de; sauer@idd.tu-darmstadt.de; doersam@idd.tu-darmstadt.de

1 Technical University of Darmstadt, Department of Mechanical Engineering, Institute of Printing Science and Technology, Magdalenenstr. 2, 64289 Darmstadt, Germany

2 Collaborative Research Center (CRC) 1194, Interaction between Transport and Wetting Processes, Project C01, Germany

Abstract

For the gravure printing process, ink transfer from the printing cylinder to the substrate is studied in the parameter regime at the very border between point and lamella splitting. In this parameter regime, ink drop deposition from adjacent gravure cells is such that, by capillary and wetting forces in the nip, the drops are at the onset of mutual coalescence. This process offers the possibility to deposit an ultimately thin and closed ink film. We discuss the particular type of pattern and defect formation in the printed layer and show that these apparently stochastic patterns have reproducible features. We claim that, besides the two known regimes of point and lamella splitting, at least one additional ink transfer regime is possible, with well-controllable wetting and ink flow dynamics. A classification scheme is proposed, based on raster-scale pattern phenomenology, by which the printer can recognize and distinguish this third regime by optical inspection of the printed product. Gaining control over this regime offers novel opportunities for gravure printing in thin-film related applications such as printed electronics and package printing.

Keywords: ink transfer, viscous fingering, Saffman-Taylor instability, functional printing, print quality

JPMTR-2016 Original scientific paper | 147
DOI  10.14622/JPMTR-2016
UDC 667.5:777-023.8

Received: 2020-12-05
Accepted: 2021-04-22

Image contrast enhancement using histogram equalisation: a bacteria colony optimisation approach

Sarah Kumar Mondal1, Arpitam Chatterjee2 and1 Bipan Tudu3

E-mail: arpitam.chatterjee@jadavpuruniversity.in

1 Department of Instrumentation and Control Engineering, Haldia Institute of Technology, Haldia, India

2 Department of Printing Engineering, Jadavpur University, Kolkata, India

3 Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata, India

Abstract

Histogram equalization (HE) is a popular method for image contrast enhancement that probabilistically maps the existing tonal levels of image to a new set of intensity levels. Despite simplicity, conventional global HE (GHE) has several limitations including visually disturbing false contouring, loss of original image features and wrong color representation in case of color images. Further modifications of GHE method have shown considerable improvement but many such techniques lack retention of original image characteristics. Computational intelligence algorithms can be a potential paradigm to address those limitations. This paper explores the scope of bacteria colony optimization (BCO) to obtain contrast enhancement while maintaining the original image characteristics. The fitness function has been formulated in frequency domain upon rigorous analysis in comparison with the results of existing contrast enhancement techniques. The paper includes implementation results with standard databases and the comparative evaluations. The comparative visual and objective evaluations confirm potential of BCO for improved performance.

Keywords: computational intelligence, Fourier analysis of contrast enhancement, image enhancement algorithm, image quality assessment

JPMTR-2103 Original scientific paper | 148
DOI  10.14622/JPMTR-2103
UDC 004.93|51-3

Received: 2021-03-22
Accepted: 2021-05-31

Examining the uncanny valley effect in virtual character design for digital games

Ugur Bakan and Ufuk Bakan

E-mail: ugur.bakan@ikc.edu.tr

Izmir Kâtip Çelebi University, Balatcik Kampusu 35620 Cigli Izmir, Turkey

Abstract

Today, games, where visuality is at the forefront, have similar features with a cinema project in terms of both the content and the technologies used. When the realistic appearance of robots and digital designs that do not fully resemble humans exceeds a point, the images created leave their place to negative emotions such as disgust, fear, and hate. The feeling of disgust emerges when the level of affinity reaches the highest level. The negative mood status which took its place in the literature as an uncanny valley is an important reference for game designers and researchers. Masahiro Mori’s uncanny valley theory about humanoid robots is used by animators and video game designers in the content creation process in video games, every day. In this study, the design evolution of Lara Croft, who has found an important place in the video game world, has been evaluated in terms of exposure to the uncanny valley. This study has used images and videos representing Lara Croft, the strong and smart female icon of the Tomb Raider games. A total of 67 undergraduate students (32 for experiments and 35 as a control group), 34 male (50.7 %), and 33 female (49.3 %), voluntarily participated in this study. In this study, the quasi-experimental design was used with experimental and control groups, since the data collection tool used to compare the experimental and control groups did not allow them to reflect the student’s past game experiences. The findings of this study suggest the following design principles: to use a high polygon count to design attractive, ideal faces that are not spooky.

Keywords: computer-generated models, video games, facial expression, human-likeness, emotion design

JPMTR-2103 Original scientific paper | 149
DOI  10.14622/JPMTR-2103
UDC 159.925-021.131:004.92

Received: 2021-04-09
Accepted: 2021-06-17