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Intelligent Monitoring of the Offset Printing Process
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
2004 (English)In: Neural Networks and Computational Intelligence - Proceedings, 2004, 173-178 p.Conference paper (Refereed)
Abstract [en]

In this paper, we present a neural networks and image analysis based approach to assessing colour deviations in an offset printing process from direct measurements on halftone multicoloured pictures--there are no measuring areas printed solely to assess the deviations. A committee of neural networks is trained to assess the ink proportions in a small image area. From only one measurement the trained committee is capable of estimating the actual amount of printing inks dispersed on paper in the measuring area. To match the measured image area of the printed picture with the corresponding area of the original image, when comparing the actual ink proportions with the targeted ones, properties of the 2-D Fourier transform are exploited.

Place, publisher, year, edition, pages
2004. 173-178 p.
Neural modelling, Neural network committee, Fourier transform, Offset lithographic printing
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-13770OAI: diva2:21384
Available from: 2005-01-20 Created: 2005-01-20 Last updated: 2009-02-05
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.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1147
Datorteknik, multicolour printing, printing process, colour images, colour impression, CCD-camera, Datorteknik
National Category
Computer Engineering
urn:nbn:se:liu:diva-5573 (URN)91-85297-25-9 (ISBN)
2005-02-10, 00:00 (English)
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, Linda
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