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Gray Balance Control in Sheet-Fed Offset Printing
KTH, School of Computer Science and Communication (CSC), Media Technology and Graphic Arts, Media (closed 20111231).
2008 (English)In: Proceedings of the Technical Association of the Graphic Arts, TAGA, 2008, -176 p.Conference paper (Refereed)
Abstract [en]

Newspaper printing can be controlled by visual gray balance assessment, a procedure which is widespread among newspaper printers in Sweden. In sheet-fed offset today, there is no fast and efficient way to process control the sheet-fed offset-press during production without using advanced online-systems. The control patches which are used in sheet-fed offset during the production often lack the possibility to assess gray balance, these usually work to determine full-tone ink densities and dot gain. The first objective of this study has been to evaluate the subjective quality experience (and objectively measurable factors) of print, where the quality control has been carried out based on gray balance control in sheet-fed offset. The second objective was to implement gray balance as a practical tool for the printers for a fast visual quality control in a sheet-fed offset printing. The study has shown that: 1) The gray balance can be used as a control parameter for control of quality in sheet fed offset. 2) A faster start-up and a more reliable print quality (fewer variations during production) can be achieved. The printer and the customer have access to a tool which facilitates communication, generates fewer misunderstandings, leads to less product returns and less production losses. With this tool it is easier for the printer to visually detect deviations without time consuming physical measurements. Also troubleshooting is easier; printers know instantly where the deviation is and can attend to it immediately.

Place, publisher, year, edition, pages
2008. -176 p.
Keyword [en]
Gray balance, Quality, Sheet-fed offset, Strip
National Category
Media and Communication Technology
URN: urn:nbn:se:kth:diva-12431ScopusID: 2-s2.0-78649657096OAI: diva2:311423
60th Annual Technical Conference of the Technical Association of the Graphic Arts, TAGA - Disseminating Graphic Arts Research Internationally since 1948; San Francisco, CA; United States; 16 March 2008 through 19 March 2008

QC 20100617

Available from: 2010-04-21 Created: 2010-04-21 Last updated: 2014-10-10Bibliographically approved
In thesis
1. Toward better image reproduction in offset
Open this publication in new window or tab >>Toward better image reproduction in offset
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis has focused on color reproduction processes in the graphics field and is based on theoretical research and practical studies. The purpose of this thesis was to investigate how new tools and tools adapted to a specific production set-up can be used to raise awareness regarding the quality and workflow of images and image processing for sheet-fed offset within the graphic industry.

The work is divided in to the following three study areas with several sub-studies:

1) The first research goal of the thesis is to identify knowledge levels regarding color separation of images and demand specifications within printing houses.

2) The second research goal is to investigate whether novel tools and new terminology can help to increase the knowledge level regarding color management

3) The third goal is to investigate whether process specific adaptation of key color control tools can improve quality levels

Three surveys about color reproduction (focusing on level of knowledge concerning color separation, the use of ICC-profiles and demand specifications for controlled color reproduction) at printing companies in Sweden were made between 2000 and 2004. The surveys indicated a serious problem in the graphic arts industry, involving both an insufficient understanding of color management and a lack of communication.

An important part of the work was to assist in make color management understandable for users and thereby optimize printing. For this purpose, digital test forms have been developed. The developed tools, together with descriptive material, will facilitate the understanding of color management issues. Definitions within the field of color separations have been examined, and changes have been suggested. A new term for separation “Compensation by Black”, CB, has been suggested, instead of e.g. GCR and UCR.

Is it possible to adapt the different parts of the process chain in order to achieve an improved production? Yes! This work has developed the method for adaptation of the scanne rtest chart, the printing test chart for image categorization and the control strip forsheet-fed offset using gray balance. This thesis suggests that it is possible to produce a custom-made IT8 target test chart for scanners and achieve a result at least similar to or even better than the standard test charts on the market. This work has also shown that itis possible to adapt the test chart for printing to image category. The result showed that low-key image separated by the image-adapted test chart showed more detail in the dark areas than a low-key image separated by the standard test chart, in the prints on a coated paper. The result from the adaptation of a control strip for sheet-fed offset showed that gray balance can be used as a control parameter for quality control in sheet-fed offset.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 133 p.
Trita-CSC-A, ISSN 1653-5723 ; 2010:06
Images, offset, printing, ICC, color, gamut, profile, calibration, separation, GCR, UCR, characterization, gray balance
National Category
Computer Science Media and Communications
urn:nbn:se:kth:diva-12432 (URN)978-91-7415-609-6 (ISBN)
Public defence
2010-05-03, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
QC20100617Available from: 2010-04-21 Created: 2010-04-21 Last updated: 2010-08-26Bibliographically approved

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