liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • 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
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hauck, Shahram
    Dept. of Informatics and Media, Beuth Hochschule Berlin University of Applied Sciences, Berlin, Germany,.
    A novel spectral trapping model for color halftones2018In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 7, no 3Article in journal (Refereed)
    Abstract [en]

    The amount of trapping has a great impact on the gray balance and color reproduction of printed products. The conventional trapping models are print density based and give percentage values to estimate the effect of trapping. In an earlier paper (Hauck and Gooran, 2011), a spectral trapping model was proposed, that defines the trapping effect as the DE* ab colorimetric differences between the real ink overlap (measurements) and the ideal ink overlap. All the trapping models proposed so far, however, only calculate the trapping value for full-tone (solid) ink overlap. As the trapping value for full-tone ink overlap could be overestimating the actual ink trapping effect for halftones, it is important to be able to also approximate the trapping value of color halftones. Furthermore, for a detailed gray balance shift analysis, there is a need to estimate the trapping effect for specific color halftones.

    In the present paper, we propose a novel spectral trapping model that delivers the trapping value as DE* ab color difference for color halftones taking into account secondary and tertiary ink overlap.

    The results of the experiments show that the trapping value for color halftones are much smaller than their corresponding trapping value at full-tone, but trapping value of halftones, besides other common quality parameters, should still be considered if some quality inaccuracy, such as gray balance shift, occurs in a print production.

  • 2.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Paula, Zitinski Elias
    Linköping University, Department of Science and Technology.
    Multi-channel dot-off-dot halftoning compensating for slightly chromatic gray inks2015In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 4, no 2, p. 119-127Article in journal (Refereed)
    Abstract [en]

    Printing using more than four ink channels visually improves the reproduction but causes challenges with the ink layer thickness that could lead to ink bleeding and color inaccuracy. A color image is commonly prepared for print by first being separated into the colorant channels the intended print device utilizes. The separations are usually halftoned independently, resulting in random dot overlap with possible spots where all colorants are printed. A multilevel halftoning algorithm that processes each channel so that it is printed with multiple inks of the same hue value has already been applied to three achromatic inks – photo gray, gray, black – in a real paper–ink setup. Results proved a successful multilevel halftone implementation workflow using multiple inks while avoiding dot-on-dot placement. However, in this approach, the gray inks were assumed to be neutral and lighter versions of black, an assumption that may cause a ΔE*ab color difference as high as 5. In the present paper an alternative approach, based on dot-off-dot halftoning avoiding dot overlap, is proposed andapplied to the same three inks. A look-up table driven separation procedure of the original image into the three channels is also proposed, which, combined with dot-off-dot halftoning, results in a ΔE*ab color difference not larger than 1.8. Results show that the dot-off-dot halftoned images are visually pleasant without any artifacts in tone transitions. The proposed approach has three main advantages to the commonly used independent halftoning. One being that dot overlap between different inks is completely avoided, i.e. photo gray, gray and black in the present work. The other one is that the results are less grainy compared to independent channel halftoning. The third one is that dot-off-dot halftoning consumes less ink than independent halftoning when reproducing the same color.

  • 3.
    Hauck, Shahram
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    A novel method to determine register variation of a press by a densitometry tool2015In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 4, no 2, p. 95-102Article in journal (Refereed)
    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.

  • 4.
    Hauck, Shahram
    et al.
    Dept. of Informatics and Media, Beuth Hochschule Berlin University of Applied Sciences, Berlin, Germany.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Automated CtP calibration system in an offset printing workflow2018In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 7, no 3Article in journal (Refereed)
    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 makes the printing plate.

    One of the most important quality criteria for printing is to control the dot gain level. It is crucial to have the dot gain level within an acceptable range, defined by ISO 12647-2/13. This is done by dot gain compensation methods in the Raster Image Processor (RIP). Dot gain compensation, which is also referred to as CtP calibration, is however a complicated task in offset printing because of the huge number of parameters affecting dot gain. The conventional CtP calibration methods for an offset printing process, which are very time and resource demanding and hence expensive, mostly uses one to five dot gain correction curves as maximum. The proposed CtP calibration method in this paper, calibrates the dot gain according to ISO 12647-2/13 recommendations fully automatically parallel to the print production.

    Besides that, there is no limitation of the number of the needed dot gain correction curves. This method, which is much more efficient and economically beneficial compared to conventional CtP calibration methods, also makes the printing production very accurate in terms of dot gain value. This automated CtP calibration system for offset printing workflow is introduced and described in this paper.

  • 5.
    Hauck, Shahram
    et al.
    Beuth Hochschule, Berlin University of Applied Sciences, Germany.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Investigation of the effect of ink penetration and gloss on a proposed spectral trapping model for high quality glossy coated paper2013In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 2, no 4, p. 235-244Article in journal (Refereed)
    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.

  • 6.
    Qu, Yuanyuan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    A simple color separation model based on colorimetric and spectral data2013In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. II, no 2, p. 77-86Article in journal (Refereed)
    Abstract [en]

    A color separation model which separates a target color inside the gamut of a printing system into the combination of process inks used in the system is a crucial part of the printing procedure. A simple color separation model for CMY printing is presented in this paper. It is based on a color prediction model proposed in our previous papers. This color prediction model, which was based on CIEXYZ (CIELAB) values, is extended in this paper to work also for spectral data. Therefore, the color separation model is executable for target colors represented by both CIELAB and spectral data. Two experiments are designed and carried out to evaluate the accuracy of the proposed models. The first experiment proves the accuracy and stability of the forward (color prediction) model. The second experiment shows that our simple inverse model (color separation) has a satisfying accuracy for different target colors in terms of giving less ink consumption and small CIELAB (ΔE94) or small spectrum difference (ΔRMS). The proposed color separation model has the potential to be applied to practical printing systems due to its simplicity and accuracy.

  • 7.
    Willfahrt, Andreas
    et al.
    Stuttgart Media University, Hochschule der Medien (HdM), Stuttgart, Germany.
    Steiner, Erich
    Stuttgart Media University, Hochschule der Medien (HdM), Stuttgart, Germany.
    Model for calculation of design and electrical parameters of thermoelectric generators2012In: Journal of Print and Media Technology Research, ISSN 2223-8905, Vol. 1, no 4, p. 247-257Article in journal (Refereed)
    Abstract [en]

    Energy harvesting - the conversion of ambient energy into electrical energy - is a frequently used term nowadays. Several conversion principles are available, e.g., photovoltaics, wind power and water power. Lesser-known are thermoelectric generators (TEG) although they were already studied actively during and after the world wars in the 20th century (Caltech Material Science, n. d.). In this work, the authors present a mathematical model for the calculation of input or output parameters of printed thermoelectric generators. The model is strongly related to existing models (Freunek et al., 2009; Rowe, 1995; Glatz et al., 2006) for conventionally produced TEGs as well as for printed TEGs. Thermal effects as investtigated by Freunek et al. (2009; 2010) could be included. In order to demonstrate the benefit of the model, two examples of calculations are presented. The parameters of the materials are derived from existing printing inks reported elsewhere (Chen et al., 2011; Wuesten and Potje-Kamloth, 2008; Zhang et al., 2010; Liu et al., 2011; Bubnova et al., 2011). The printing settings are chosen based on feasibility and convenience.

1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • 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