Journal of Graphic engineering and design

Volume 1 (2010), Number 1

0. Complete issue

1. Multi-color 2D datamatrix codes with poorly readable colors
Pages: 1-8
Urška Bogataj, Tadeja Muck, Branka Lozo, Arjana Žitnik
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Abstract

Datamatrix code is a type of 2D codes that can encode much more data on the same or smaller area than the linear barcodes. This makes 2D codes usable for marking even very small items. 2D codes can be decoded by the readers in retails but also with the mobile phones equipped with camera and appropriate software. 2D codes can be depicted in different materials or printed on different printing substrates. The application area of the codes is broad, from magazines and newspapers to posters and packaging. Successful reading of 2D codes is possible if the code is printed in appropriate contrast between the printing ink and substrate, like black ink printed on white matt paper. Problems can occur if the code is printed in colors. The readability of 2D Datamatrix codes printed in cyan, magenta, yellow and black was studied. Yellow is proved to be poorly readable. In addition, the bi-colored and multi-colored 2D Datamatrix codes were studied. When four colors are used in creation of the 2D Datamatrix code, poorly readable elements, yellow codewords, may cause the reading failure. 2D Datamatix codes are capable to ensure good readability even if they contain a defined number of poorly readable codewords due to the Reed – Solomon error-correction system. The aim of the study was to investigate the effect of using yellow printed, poorly readable, codewords in the multi-colored 2D Datamatrix code on the code readability.

2. Black point compensation and its influence on image appearance
Pages: 9-15
Dragoljub Novaković, Igor Karlović, Ivana Tomić
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Abstract

Black point compensation (BPC) is a feature developed by the Adobe company in order to address the problem caused by differences between the darkest level of black achievable on input and output devices and it’s not a part of ICC specifications. If it’s turned on – black colour of input device will be mapped into the black colour of an output device; if it’s not – mapping will be performed regarding the rendering intents. By default this option is turned on, which is a good solution in most cases. The aim of the work is to accurately define when black point compensation should be activated, and when not, and also to investigate influence of different colour management modules on colours allocation after conversions, in accordance to their psychophysical values. Regarding theoretical background and results of experimental part of this work conclusions about BPC usability are carried out.

3. Integrated maintenance management model in the printing industry
Pages: 16-22
Csaba Horváth
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Abstract

Rapid technological and economic changes are setting radically new task for maintenance divisions of printing works. In this dissertation the author provides a summary on the possible approaches for the adoption to the new requirements. He formulates his situation analysis based on an exhaustive questionnaire survey, and points out the currents of changes and challenges caused by the expected developments in the maintenance field of the printing industry.
Based on the possible answers on these challenges, the Author has compiled a - yet missing - maintenance management model that encompasses the maintenance specialties of the industry, as well as the professional heritage and the latest scientific accomplishments in the discipline of maintenance.
The model is based on the widely accepted quality focused maintenance approach, that is supplemented by the Author with four new aspects - 1) reliability-focused culture, 2) quality management system, 3) employment of external service provides, 4) maintenance characteristics specific to printing machinery - determining their effects and integrating them into one single system.
In order to construct the model, the Author develops specific solutions that can be seen as own scientific achievements on the specification of maintenance characteristics of printing machinery; on the efficiency improving applications of quality management systems, modern knowledge management and reliability focused corporate culture; and on the implementation of a maintenance information system.

4. The influence of surface topography of UV coated and printed cardboard on the print gloss
Pages: 23-31
Igor Karlović, Dragoljub Novaković, Erzsébet Novotny
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Abstract

The incident light on the printed surface undergoes through several processes of scattering, absorbtion and reflection depending on the surface topography and structure of the material. The specular part of the surface reflection is commonly attributed as the geometric component of the reflection, and when measured is associated with specular gloss. The diffuse part of the surface reflection contains the chromatic part of the reflection and is commonly calculated through colorimetric values. Using UV coatings as surface enhacement materials which affect the optical properties of coated surfaces and final appearance of the printed product forms new surface topography over the existing one. We have investigated the influence of three different amounts of UV glossy and matte oveprint coating on the measured specular gloss of printed cardboard samples. The different amount of coatings on the printed samples were achived using three different screen stencils of 180 threads/cm, 150 threads/cm and 120 threads/cm thread count. The cardboard samples were analysed with AFM and SEM microscopes to obtain surface topography and roughness values which were evaluated with the measured geometric values speficied as instrumental gloss. The surfaces with a specific amount of UV coatings showed a new formed topography which influences the reflection of light. The changes in topography were evaluated through surface roughness parameters which showed a decline of surface roughness with tht additional ammount of glossy and matte coatings. The obtained and calculated correlations show there is a high correlation between coating ammount and surface roughness change and gloss for the glossy UV coating. The results for the matte UV coatings showed lower correlation for the gloss and surface roughness.

5. Changes in the surface roughness of aluminium oxide (non-printing) areas on offset printing plate depending on number of imprints
Pages: 32-38
Živko Pavlović, Dragoljub Novaković, Sandra Dedijer, Magdolna Apro
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Abstract

A printing and non-printing surface structure of the offset printing forms are key factors in maintaining the conventional offset printing. The main characteristics of the surface are: physical and chemical structure, surface tension and surface roughness. Surface topography is one of the critical factors which could cause the instability in the quality performance and the durability of the printing forms. During the printing process these characteristics change and directly influence the print. Performed investigations are based on the fact that the changes in physicalchemical properties of the non-printing areas as well as the changes in the surface micro structure of the printing forms directly influence the quality of the reproduction. In this paper, the behaviour of non-printing elements of a thermal CTP plate developed in a fresh developer and used for a print run of 123.000, 177.000 and 300.000 copies on a web offset heat-set printing press has been investigated. Investigation made in a paper showed that high depth of focus SEM (Scanning Electron Microscope) can provide detailed topographical information about the surface, but cannot provide quantitative topographical information. Due to this fact, the printing forms have been also observed and analysed before and after the print run by a mechanical stylus profilometer. The investigations reveal the appearance of the physical changes as well as the geometrical ones. As a result of these changes, the influence of a fountain solution on the printing form may also vary, as well as the balance between the ink and the fountain solution during the printing process.

6. Influence of the Print Run on Silver Halide Printing Plates
Pages: 39-44
Tomislav Cigula, Sanja Mahović Poljaček, Miroslav Gojo
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Abstract

The most common printing technique today is lithography. The difference between printing and nonprinting areas on a printing plate is accomplished by opposite physical and chemical properties of those areas (MacPhee, 1998). The printing areas are made of photoactive layer that attracts oil and chemical substances with oil solvent – printing inks. The nonprinting areas are made of aluminium-oxide which attracts water based substances – the fountain solution. There are many of various types of photoactive layer which are used for production of offset printing plates, among others is silver halide layer. The usage of the silver halide technology in the graphic reproduction is not a novelty. The filmmaking phase is based on the usage of the silver halide as the photographically active ingredient, for instance, AgBr (silver bromide). The new, digital plate making technology (Computer to Plate, CtP) eliminates the filmmaking phase and therefore enables control of the printing plate’s exposure made by computer. CtP technology eliminates the filmmaking phase, but it also results with the reduction of needed material quantities and required time for the production (Limburg, 1994; Seydel, 1996). In this paper the basis of the graphic reproduction by using the silver halide digital printing plates was described. The changes of the AgX copying layer and the surface of the aluminium base in the printing process have been observed. The surface characteristics were determined by measuring the relevant surface roughness parameters. In addition, measurements of coverage values on the prints, detailed at smaller print run, were conducted. Results showed that surface changes on the printing plate are changing during printing process and that these changes influence transfer of the printing ink on the printing substrate. These measurements proved to be of great interest in the graphic reproduction as they enable us to determine consistency of the printing plates during the printing process, to predict the endurance as well as to define the print run which will result with optimal quality prints.

JOURNAL OF GRAPHIC ENGINEERING AND DESIGN

Volume 1 (2010), Number 1

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