December 2019

A letter from the Editor
Gorazd Golob

Editor-in-chief

The latest issue of 2019 is slightly different from previous issues, but it is also groundbreaking in terms of open access publishing mode. Despite several articles in review and revision, only three articles were accepted for publication in the last days of December.

The first one is an original scientific paper on color changes resulting from the lamination of prints, distinguished by a comparison of the heuristic and artificial neural network approach for predicting them. The authors have verified the suitability of both methods and proved the advantages of the latter one.

The second article is classified as professional communication and is based on a study of the adequacy of standards for quality assurance of inkjet printing when printing on coated cartons. The discussion and conclusions raise a number of questions, both regarding the continuation and deepening of the research, as well as the need for extension of accepted standards that do not fully cover the wide range of substrates and inks used in practice.

The third article is the position paper, the cathegory that appears in the Journal for the first time. Based on years of extensive experience, the author highlights his views on the problems of knowledge of technology fundamentals as general expertise in industrial environments,  research in graphic technology, and teaching, liiustrated by examples of image reproduction quality with a focus on prepress. We hope his views will be a trigger of argumentative discussion, as we are still witnessing the rapid development of technology in this field, as well as changes in industrial practice and in the response of print-buyers and end-users to new challenges.

The editor Markéta Držková (marketa.drzkova@jpmtr.org) in the Topicalities prepared an overwiev of recent publications from CIE and some revised and new standards published by CIE/ISO are introduced, together with an update of Fogra research projects.

From the bookshelf, you can choose from a number of books covering inkjet print heads design, vision, color, typography, graphic design, and communication, including book production history.

Three doctoral theses are also presented, pointing to current research areas that cover a much broader range of content than just conventional printed paper, cardboard or packaging materials.

At Helmut-Schmidt-University in Hamburg, Felix Heinrich defended his thesis in the field of printed electronics, focusing on the mechanical strength analysis of multifunctional composites enhanced with printed electronics, which can be used as sensors for health monitoring and study of methods for improving their properties.

Clara Pérez Fuster defended her thesis in the field of design and characterization of organic thin-film transistors for chemical sensing and analytes at the Polytechnic University of Valencia. The functionality and applicability of these sensors, using screen printing technique among other methods, have been successfully verified. Her work also included the development and verification of low-cost measuring equipment for specific needs in this field.

Uttam Kumar successfully finished his thesis at the School of Materials Science and Engineering in Sydney. The topic of his research was environmental sustainability, especially electronic waste in the form of end-of-life printers and toner residuals. He implemented efficient methods for the production of synthetic oil and activated carbon, which can be used as electrodes in supercapacitors and batteries.

As usual, Topicalities conclude with the review of events in the first months of the year 2020.

With the decision of the iarigai Board, the publisher of the Journal, this publication is now available as full open access, meaning that the online edition will no longer be password protected for six months and thus freely available at https://iarigai.com/publications/journals/. For anyone who wants to receive a print Journal, this option remains available, of course at an appropriate price. It is also important that there is no fee charged for authors who intend to publish the results of their research work. In the coming months, we anticipate some more positive changes to the Journals publishing and indexing, and you will be informed in a timely and appropriate manner.

We again invite you to participate with your contributions, as only the publication of your research achievements and thus the open possibility of using them as a reference in any other publication, in further research or in the industry leads to success. May 2020 be a successful year for all of us.

Ljubljana, December 2019

Prediction of lamination-induced colour shifts for UV offset printings by using a heuristic approach as well as machine learning techniques

Tim Stiene, Peter Urban and Jorge Manuel Rodriguez-Giles
E-mails: urban@uni-wuppertal.de
; albaodila@hotmail.com
School of Electrical, Information and Media Engineering, Rainer-Gruenter-Straße 21, D-42119 Wuppertal

Abstract

To investigate two approaches for the prediction of spectral colour changes, UV offset-printed test charts were laminated with polybutylene terephthalate films in three thicknesses and measured spectrophotometrically before and after lamination. This enabled the identification of the resulting colour shift for each patch. Mean colour deviations of 3.4 ∆E00 were determined while the strength of a colour shift depended on the initial colour patch lightness and the presence of paper white. To predict spectral reflections, a heuristic approach, based on the calculation of wavelength-dependent transmission of the lamination, is presented. A mean accuracy of 1.44 ∆E00 between predictions and actual measured coated reflections was achieved. The method still shows potential for improvements in the prediction of the paper white after lamination. In a second approach, an artificial neural network (ANN) was applied to evaluate the performance of machine learning on this topic as well. After training and validation, using the ANN for spectral prediction led to a higher precision with a mean ∆E00 of 0.6. In conclusion, both approaches obtain useful results whereby the ANN predictions are significantly more accurate. The investigation also demonstrates the potential of machine learning in the field of print and media technologies in general and in colour science in particular.

Keywords: colour difference, spectral prediction, lamination, neural network, colour measurement

JPMTR 128 | 1912 Original scientific paper
DOI 10.14622/JPMTR-1912
UDC 774.8-024.25-021.383|004.02

Received: 2019-11-27
Accepted: 2019-12-31

Comparing quality attributes of coated cardboards for inkjet printing by using different methods

Sandra Rosalen and Johannes Backhaus
E-mails: srosalen@uni-wuppertal.de; jbackhaus@uni-wuppertal.de
Bergische Universität Wuppertal, Rainer-Gruenter-Straße 21, 42119 Wuppertal, Germany

Abstract

The reproduction of fine details is an important aspect in print quality and influences both the legibility and thus readability of texts and the decodability of 1D and 2D codes. Technical standards related to digital printing, such as ISO/IEC 24790:2017, predominantly evaluate printing systems. In this study, the focus is on media as the object of analysis. The evaluation of character and line image quality attributes was used to analyze the reproduction on different media comprising seven primed and non-primed cardboards printed with dye and pigment based inks. The tests were compared with the resolution of Siemens stars, line reflection and dot gain values. This study demonstrates the applicability of ISO/IEC 24790:2017 for inkjet media evaluation and shows a proper correlation between different methods of print evaluation.

Keywords: print media evaluation, ISO/IEC 24790:2017, ISO/TS 15311-2:2018, dot gain, Siemens star

JPMTR 1906 Professional communication
DOI 10.14622/JPMTR-1906
UDC 681.6:004.356:676.2

Received: 2019-03-29
Accepted: 2019-11-20

To take for granted or question the technology fundamentals in research and learning?

Yuri V. Kuznetsov
E-mail: yurivk@mail.ru
St. Petersburg State Institute of Cinema and Television, ul. Pravdy 13, St. Petersburg, 191119, Russian Federation

Abstract

With growing variety of novel printing methods and facilities for their computerized control the rethinking becomes urgent for some fundamental technology issues which just pretend to be clear but are, in fact, the empirical data taken for granted from a long term industry experiences. Based on the research results and educational competencies of author the philosophy of choosing the screen frequency, geometry and press settings, the dot gain nature and multipurpose use of black ink in CMYK are analyzed and experimentally illustrated.

Keywords: educational paradigm, technology fundamentals, new knowledge, source image, print channel

JPMTR 1908 Position paper
DOI 10.14622/JPMTR-1908
UDC 303.6|62-9

Received: 2019-07-29
Accepted: 2019-11-26