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Hauck, Shahram
Publications (7 of 7) Show all publications
Hauck, S. & Gooran, S. (2015). A novel method to determine register variation of a press by a densitometry tool. Journal of Print and Media Technology Research, 4(2), 95-102
Open this publication in new window or tab >>A novel method to determine register variation of a press by a densitometry tool
2015 (English)In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 4, no 2, p. 95-102Article in journal (Refereed) Published
Abstract [en]

The print quality of a printing machine highly depends on good register variation values. The measuring of register variation is very important for putting a multicolor press in operation or for its repair and service. The manufacturers of print presses also need the evaluation of register variation to develop new products. The current industry standard method for measuring the register variation is based on image processing, which is a very expensive method. It was a great demand to determine the register variation by an alternative and affordable technique. In the present paper we introduce a new method to determine the register variation based on densitometry. In order to create a new method, a special color test target has been designed. The input of the method is the densitometric measurement values, and its output is the register variation value. The results of the method have been compared with those of an image processing method and the correlation coefficient between the results is almost 0.9. Since in the proposed method only a densitometer is needed, it can be considered as a very inexpensive alternative to the image processing methods. The results were also demonstrated to different specialists of a manufacturer of print press and received very positive feedback.

National Category
Media and Communication Technology
Identifiers
urn:nbn:se:liu:diva-120256 (URN)10.14622/JPMTR-1441 (DOI)
Available from: 2015-07-22 Created: 2015-07-22 Last updated: 2018-02-13
Hauck, S. (2015). Automated CtP Calibration for Offset Printing: Dot gain compensation, register variation and trapping evaluation. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Automated CtP Calibration for Offset Printing: Dot gain compensation, register variation and trapping evaluation
2015 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

Although offset printing has been and still is the most common printing technology for color print productions, its print productions are subject to variations due to environmental and process parameters. Therefore, it is very important to frequently control the print production quality criteria in order to make the process predictable, reproducible and stable. One of the most important parts in a modern industrial offset printing is Computer to Plate (CtP), which exposes the printing plate.

One of the most important quality criteria for printing is to control the dot gain level. Dot gain refers to an important phenomenon that causes the printed elements to appear larger than their reference size sent to the CtP. It is crucial to have the dot gain level within an acceptable range, defined by ISO 12647-2 for offset printing. This is done by dot gain compensation methods in the Raster Image Processor (RIP). Dot gain compensation is however a complicated task in offset printing because of the huge number of parameters affecting dot gain. Another important quality criterion affecting the print quality in offset is the register variation caused by the misplacement of printing sheet in the printing unit. Register variation causes tone value variations, gray balance variation and blurred image details. Trapping is another important print quality criterion that should be measured in an offset printing process. Trapping occurs when the inks in different printing units are printed wet-on-wet in a multi-color offset printing machine. Trapping affects the gray balance and makes the resulting colors of overlapped inks pale.

In this dissertation three different dot gain compensation methods are discussed. The most accurate and efficient dot gain compensation method, which is noniterative, has been tested, evaluated and applied using many offset printing workflows. To further increase the accuracy of this method, an approach to effectively select the correction points of a RIP with limited number of correction points, has also been proposed. Correction points are the tone values needed to be set in the RIP to define a dot gain compensation curve.

To fulfill the requirement of having the register variation within the allowed range, it has to be measured and quantified. There have been two novel models proposed in this dissertation that determine the register variation value. One of the models is based on spectrophotometry and the other one on densitometry. The proposed methods have been evaluated by comparison to the industrial image processing based register variation model, which is expensive and not available in most printing companies. The results of all models were comparable, verifying that the proposed models are good  alternatives to the image processing based model.

The existing models determining the trapping values are based on densitometric measurements and quantify the trapping effect by a percentage value. In this dissertation, a novel trapping model is proposed that quantifies the trapping effect by a color difference metric, i.e. , which is more useful and understandable for print machine operators. The comparison between the proposed trapping model and the existing models has shown very good correlations and verified that the proposed model has a bigger dynamic range. The proposed trapping model has also been extended to take into account the effect of ink penetration and gloss. The extended model has been tested using a  high glossy coated paper and the results have shown that the gloss and ink penetration can be neglected for this type of paper.

An automated CtP calibration system for offset printing workflow has been introduced and described in this dissertation. This method is a good solution to generate the needed huge numbers of dot gain compensation curves to have an accurate CtP calibration.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. p. 149
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1673
National Category
Media and Communication Technology Computer and Information Sciences
Identifiers
urn:nbn:se:liu:diva-119366 (URN)10.3384/diss.diva-119366 (DOI)978-91-7519-061-7 (ISBN)
Public defence
2015-09-08, K3, Kåkenhus, Campus Norrköping, Norrköping, 10:00 (English)
Opponent
Supervisors
Available from: 2015-06-15 Created: 2015-06-15 Last updated: 2018-01-11Bibliographically approved
Hauck, S. & Gooran, S. (2013). Investigation of the effect of ink penetration and gloss on a proposed spectral trapping model for high quality glossy coated paper. Journal of Print and Media Technology Research, 2(4), 235-244
Open this publication in new window or tab >>Investigation of the effect of ink penetration and gloss on a proposed spectral trapping model for high quality glossy coated paper
2013 (English)In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 2, no 4, p. 235-244Article in journal (Refereed) Published
Abstract [en]

The amount of trapping has a great impact on the gray balance and color reproduction of printed products. Therefore, conventional print density based models to estimate the effect of trapping have been created, which only give percentage values. In an earlier paper (Hauck and Gooran, 2011) we have proposed a trapping model based on reflectance spectra, which defines the trapping effect as the DE*ab colorimetric differences between the measurements and the calculated values. Therefore, this model is more useful and meaningful for the press machine operators than the conventional trapping models. The surface (gloss) and ground (ink penetration) effect may have an impact on the print results depending on the substrate and inks but these effects have mainly been ignored in all previous trapping models. In the present paper, we extend our earlier model to investigate the impact of both effects for high quality glossy coated paper and a set of sheet-fed offset inks. An ink mileage test was carried out to find the surface and ink penetration effects. The results of our investigation demonstrates that these two effects compensate each other and their total impact is almost negligible for the tested materials. This means that our previously proposed model can successfully be used for high quality glossy coated papers to determine the trapping value.

Place, publisher, year, edition, pages
International Association of Research Organizations for the Information, Media and Graphic Arts Industrie (IARIGAI), 2013
Keywords
Ink trapping in offset, Ink component penetration, Surface Effects on reflectance, Color difference (ΔE*ab), Print quality, Modeling ink trapping respons
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:liu:diva-105688 (URN)
Available from: 2014-04-02 Created: 2014-04-02 Last updated: 2017-12-05Bibliographically approved
Hauck, S. & Gooran, S. (2011). A Networked Workflow for a Fully Automated CtP Calibration System. In: Proc. International Circle of Educational Institutes for Graphic Arts (IC). Paper presented at International Circle of Educational Institutes for Graphic Arts (IC), Sept 2011, Norrköping, Sweden.
Open this publication in new window or tab >>A Networked Workflow for a Fully Automated CtP Calibration System
2011 (English)In: Proc. International Circle of Educational Institutes for Graphic Arts (IC), 2011Conference paper, Published paper (Other academic)
Abstract [en]

One of the most important targets on the graphic market is to realize standardization. The standardization defines the target value of solid Lab and dot gain in printing process. In addition the tolerance range of these two values will be described by standardization. The correct dot gain will be achieved during the measuring of the dot gain in printing process by the additional calculation of a correction curve well known as Print Characteristic Curve (PCC) [1]. The Raster Image Processor (RIP) needs the PCC for the imaging of printing plate with the correct tone value. In this paper we will propose a Networked Workflow (figure 1) with the Workflow Control System (or alternatively a MIS Management Information System). This Networked Workflow is necessary for the realization of a Fully Automated CtP Calibration System.

National Category
Media Engineering
Identifiers
urn:nbn:se:liu:diva-76848 (URN)
Conference
International Circle of Educational Institutes for Graphic Arts (IC), Sept 2011, Norrköping, Sweden
Available from: 2012-04-20 Created: 2012-04-20 Last updated: 2012-04-27
Hauck, S. & Gooran, S. (2011). An Alternative Computational Method of Trapping for the Print Machine Operators. In: Proc. TAGA (Technical Association of the Graphic Arts): . Paper presented at TAGA (Technical Association of the Graphic Arts), March 2011, Pittsburgh, PA, USA (pp. 363-373). Sewickley, PA, USA: Technical Association of the Graphic Arts
Open this publication in new window or tab >>An Alternative Computational Method of Trapping for the Print Machine Operators
2011 (English)In: Proc. TAGA (Technical Association of the Graphic Arts), Sewickley, PA, USA: Technical Association of the Graphic Arts , 2011, p. 363-373Conference paper, Published paper (Other academic)
Abstract [en]

In a multicolor offset press the process inks (kcmy) will be printed consecutively on the substrate from oneprinting unit to the other. The printing dots and elements in different process color will be printed either isolated, partly orcompletely overprinted depending on the halftoning. In a multicolor press the inks will be printed wet on wet. That meansthat in the area where process inks overlap each other one or more inks will be printed on another ink which is not dryenough. The adhesive power between the wet inks is different and less compared to the adhesive power between one inkprinted on the top of a less wet ink or even a completely dry ink. The adhesive power between the substrate and printed ink isalso different from the adhesive power of one ink on the top of another one. Depending on this adhesive power and the inks’inner cohesion power the thickness of the second printed ink varies. The thickness or amount of the second printed ink on thefirst one can be determined; its value is called trapping. The amount of the trapping will also be changed due to differentparameters such as ink temperature, dampening, printing speed etc. An important outcome is that the gray balance and thecolor appearance (secondary and tertiary colors) of the printed product also depend very much on the trapping’s amount. Thatshows how important it is to have an explicit value for the trapping. The amount of the second printed inks will bedetermined by trapping formulas. This value should be useful for the printer at the press. Unfortunately, the conventionaltrapping formulas are only useful for the “relative” comparison of trapping between two print products. All the conventionalformulas for trapping only deliver the amount of the second printed ink on the top of the first one in percent. This value for itsown (e.g. 63%) is not really useful and meaningful for print machine operators. There are three different formulas fordetermining trapping. These are Preucil, Ritz, and Brunner. All of them are based on density only. The results of theseformulas are different to each other, especially the Brunner formula differs to the other ones. Here a method will beintroduced which is based on spectrometry and will complement the conventional formulas.

Place, publisher, year, edition, pages
Sewickley, PA, USA: Technical Association of the Graphic Arts, 2011
Series
Technical Association of the Graphic Arts Proceedings, ISSN 0082-2299
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-68240 (URN)978-1-935185-03-1 (ISBN)
Conference
TAGA (Technical Association of the Graphic Arts), March 2011, Pittsburgh, PA, USA
Note

Shahram Hauck is Printing process and quality manager at manroland, Germany

Available from: 2011-05-23 Created: 2011-05-13 Last updated: 2013-12-03Bibliographically approved
Hauck, S. & Gooran, S. (2011). An alternative method to determinate register variation using colorimetry or densitometry tools. In: Proceedings of the Technical Association of the Graphic Arts, TAGA. Paper presented at 63rd Annual Technical Conference (Taga), March 6-9, 2011, Pittsburgh, PA, USA (pp. 340-353). Technical Association of the Graphic Arts
Open this publication in new window or tab >>An alternative method to determinate register variation using colorimetry or densitometry tools
2011 (English)In: Proceedings of the Technical Association of the Graphic Arts, TAGA, Technical Association of the Graphic Arts , 2011, p. 340-353Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Technical Association of the Graphic Arts, 2011
National Category
Media Engineering
Identifiers
urn:nbn:se:liu:diva-76845 (URN)978-1-935185-03-1 (ISBN)
Conference
63rd Annual Technical Conference (Taga), March 6-9, 2011, Pittsburgh, PA, USA
Available from: 2012-04-20 Created: 2012-04-20 Last updated: 2012-05-24
Gooran, S., Nyström, D., Namedanian, M. & Hauck, S. (2011). Measuring Register Shift and Investgating its Effect on Color Appearance for Different Halftoning. In: Proc. TAGA (Technical Association of the Graphic Arts): . Paper presented at Technical Association of the Graphic Arts), March 2011, Pittsburgh, PA, USA. Sewickley, PA, USA: Technical Association of the Graphic Arts
Open this publication in new window or tab >>Measuring Register Shift and Investgating its Effect on Color Appearance for Different Halftoning
2011 (English)In: Proc. TAGA (Technical Association of the Graphic Arts), Sewickley, PA, USA: Technical Association of the Graphic Arts , 2011Conference paper, Published paper (Other academic)
Abstract [en]

In commercial prints the halftone dots are seldom placed exactly at their corresponding positions in the digital bitmap, mostly due to the imprecise transportation of the printing substrate. In this study, we firstly present an image processing model to measure the displacement of the dots in different color separations by using a high resolution camera. By using a filter wheel equipped with a set of interference filters and sending light in different wavelength bands, it is possible to separate the different color inks. For example, for the combination of cyan and magenta inks, only cyan will be visible in the captured image if the wavelength band of the incoming light is concentrated around 700 nm. On the other hand, for the wavelength band concentrated around 500 nm only magenta will be visible. By comparing the positions of the dots in the captured images with those in the original bitmap we can measure register shift. Secondly in this study, we investigate how miss-registration affects the color appearance of the final print for different halftoning techniques. We use AM, FM first generation and FM 2nd generation halftoning methods and investigate and compare their sensitivity to register shift.

In the present work we measure the register shift for color patches printed in offset by the proposed image processing model. In order to study the effect of miss-registration on the resulting color appearance we first simulate the miss-registration in the digital bitmap. Then we print the simulated bitmap using an office laser printer. Since the miss-registration is usually negligible for digital prints, especially in lower resolution, we can examine the accuracy of our model for measuring dot displacement by comparing the simulated displacement with the measured one. Finally, by using a spectrophotometer to measure color coordinates, we can study the effect of miss-registration on the resulting color appearance for different halftoning methods by calculating the ΔElab color difference.

Place, publisher, year, edition, pages
Sewickley, PA, USA: Technical Association of the Graphic Arts, 2011
Series
Technical Association of the Graphic Arts Proceedings, ISSN 0082-2299
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-68239 (URN)
Conference
Technical Association of the Graphic Arts), March 2011, Pittsburgh, PA, USA
Available from: 2011-05-23 Created: 2011-05-13 Last updated: 2013-12-03Bibliographically approved
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