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Unsupervised colour image segmentation applied to printing quality assessment
aIntelligent Systems Laboratory, Halmstad University, Sweden.
Department of Applied Electronics, Kaunas University of Technology, Lithuania.
Department of Applied Electronics, Kaunas University of Technology, Lithuania.
2005 (English)In: Image and Vision Computing, ISSN 0262-8856, Vol. 23, no 4, 417-425 p.Article in journal (Refereed) Published
Abstract [en]

We present an option for colour image segmentation applied to printing quality assessment in offset lithographic printing by measuring an average ink dot size in halftone pictures. The segmentation is accomplished in two stages through classification of image pixels. In the first stage, rough image segmentation is performed. The results of the first segmentation stage are then utilized to collect a balanced training data set for learning refined parameters of the decision rules. The developed software is successfully used in a printing shop to assess the ink dot size on paper and printing plates.

Place, publisher, year, edition, pages
2005. Vol. 23, no 4, 417-425 p.
Keyword [en]
Colour image segmentation; Fuzzy clustering; Quality inspection; Colour printing
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-13768DOI: 10.1016/j.imavis.2004.11.003OAI: oai:DiVA.org:liu-13768DiVA: diva2:21382
Available from: 2005-01-20 Created: 2005-01-20
In thesis
1. Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
Open this publication in new window or tab >>Using Multicoloured Halftone Screens for Offset Print Quality Monitoring
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In the newspaper printing industry, offset is the dominating printing method and the use of multicolour printing has increased rapidly in newspapers during the last decade. The offset printing process relies on the assumption that an uniform film of ink of right thickness is transferred onto the printing areas. The quality of reproduction of colour images in offset printing is dependent on a number of parameters in a chain of steps and in the end it is the amount and the distribution of ink deposited on the substrate that create the sensation and thus the perceived colours. We identify three control points in the offset printing process and present methods for assessing the printing process quality in two of these points:

• Methods for determining if the printing plates carry the correct image

• Methods for determining the amount of ink deposited onto the newsprint

A new concept of colour impression is introduced as a measure of the amount of ink deposited on the newsprint. Two factors contribute to values of the colour impression, the halftone dot-size and ink density. Colour impression values are determined on gray-bars using a CCD-camera based system. Colour impression values can also be determined in an area containing an arbitrary combination of cyan magenta and yellow inks. The correct amount of ink is known either from a reference print or from prepress information. Thus, the deviation of the amount of ink can be determined that can be used as control value by a press operator or as input to a control system.

How a closed loop controller can be designed based on the colour impression values is also shown.

It is demonstrated that the methods developed can be used for off-line print quality monitoring and ink feed control, or preferably in an online system in a newspaper printing press.

Place, publisher, year, edition, pages
Institutionen för teknik och naturvetenskap, 2005. 104 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1147
Keyword
Datorteknik, multicolour printing, printing process, colour images, colour impression, CCD-camera, Datorteknik
National Category
Computer Engineering
Identifiers
urn:nbn:se:liu:diva-5573 (URN)91-85297-25-9 (ISBN)
Presentation
2005-02-10, 00:00 (English)
Supervisors
Note
Report code: LiU-TEK-LIC-2005:02.Available from: 2005-01-20 Created: 2005-01-20 Last updated: 2009-04-14

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Bergman, Lars

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf