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Presentations 2015, 2016

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Evolutions in food packaging printing

You are here: Conferences & Events * 2008 Valencia * Abstracts * 4. Color reproduction and quality

4. Color reproduction and quality

4.04. Method of objective evaluation the fine detail distortion in process of screening

Yuri V. Kuznetsov, Denis E. Zheludev

North-West Institute of Printing of the St. Petersburg
State University of Technology and Design
Dzambula lane 13, 191180 St. Petersburg, Russia
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
For objective quantitative measurement of the image fine detail distortion involved by screening the Screening Distortion Factor (SDF) is proposed. It comprises the norm of an error evaluated by superimposing of the original and halftoned resolution pattern bitmaps and counting the normalized sum of microdots, which changed their polarity (from black to white and from white to black) as result of screening. The losses in an image high spatial frequency component are illustrated by plotting the SDF curves via line test pattern frequency for variety of such screening process parameters as screen ruling, screening factor, screen and dot geometry, screening algorithm, etc.

Keywords: Distortion, halftone, MTF, screening

 

4.05. Colour management - differences arising between analogue and digital photo colour reproduction chains

Kristiina Saukkoriipi, Päivi Miettinen

Future Printing Center Oy
Kerrolankatu 2, FIN-21200 Raisio, Finland
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Abstract
This paper describes a research project studying colour rendition in each phase of the production chains from studio photographers to the printing house. Differences in colour adjustments of digital and film photos have been measured using standard colour checker charts and laboratory equipment. The typical results of these measurements are presented and discussed in this paper. The measurements and visual evaluation pinpointed the need for a colour chart with smooth colour transitions.

Keywords: Colour management, digital camera, film camera, printed image quality, printing process

 

4.06. Improved gamut boundary determination for colour gamut mapping

Arne M. Bakke, Ivar Farup, Jon Y. Hardeberg

The Norwegian Color Research Laboratory, Gjøvik University College
P.O. Box 191, N-2802 Gjøvik, Norway
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
We propose a new method for the computation of gamut boundaries, consisting of a combination of the segment maxima gamut boundary descriptor, the modified convex hull algorithm, and a sphere tessellation technique. This method gives a more uniform subdivision of the colour space into segments, and thus a more consistent level of detail over the gamut surface. First, the colour space is divided into segments around a centre point using the triangles from the tessellation algorithm. The measurement points are processed, and the point with the largest radius is found for each non-empty segment. The convex hull algorithm with a pre-processing step is then applied to these maxima points to generate the final gamut surface.

The method is tested on different input data, including data sets both with and without internal gamut points. Different numbers of segments are used, and the resulting gamut boundaries are compared with the gamuts constructed using the segment maxima method. A reference gamut is constructed for each device, and the average mismatch is calculated. Our method is shown to perform better than the segment maxima method, particularly for a higher number of segments.

Keywords: Convex hull, gamut boundary, segment maxima, sphere tessellation
 
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