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

4. Color reproduction and quality

4.01. High definition halftone printing - HDHP: background, current status and challenges of the adaptive screening developments

Yuri V. Kuznetsov

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
Along with the short overview of modern digital screening approaches the paper discusses and presents:
- basic principles of patented HDHP technique;
- HDHP method of an image files adaptive processing;
- specific, advantages and promotion issues of its practical application;
- concept of the further development of this approach potential in direction of the quantization scale spatial dispersion which is adaptive to the arbitrary contour of an image.

The samples of test images and microphotographs of fragments of illustrative print jobs using the HDHP technology are also presented.

Keywords: Fine detail, resolution, screening, sharpness, tone rendition
 

4.02. Finding optimum screen combinations for flexible hybrid screening technologies in flexography lithography

Yung-Cheng Hsieh, Hui-Wen Cheng

Department of Graphic Communication Arts, National Taiwan University of Arts
59, Section 1, Ta-Kuang Rd., Pan-Chiao City
Taipei County, Taiwan R.O.C.
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
This study investigates the use of AM/FM hybrid screening in conjunction with computer to plate (CTP) technology in order to obtain an optimum hybrid screening combination for the flexography printing process. The study employs the true experimental method to design 11 different hybrid (FM-AM-FM) screening combinations in accordance with Kodak/Creo's Maxtone hybrid screening technology. Hybrid screening and CTP technologies were used in flexography to print a specially-designed test form on PVC substrate. Differences in print attributes between PVC substrates printed via the 11 hybrid screening combinations were measured, and statistical analyses were used to identify a combination with an optimal FM-AM-FM tone percentage. It is hoped that the results of this study can help flexography printers to better understand the characteristics of various screening techniques, allowing them to improve printing quality and achieve the highest customer satisfaction. The best hybrid screening combination of FM-AM-FM (highlight-midtone-shadow) found in this study is provided to printers as a reference enabling them to improve production effectiveness and quality, while reducing printing costs and waste, enabling the quality of flexography in Taiwan to progress.

Keywords: AM screening, flexography, FM screening, hybrid screening, print attributes

 

4.03. Implementation of global and local thresholding algorithms in image segmentation of coloured prints

Miha Lazar, Aleš Hladnik

Faculty of Natural Sciences and Engineering, University of Ljubljana
Snežniška 5, SI-1000 Ljubljana
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Abstract
Segmentation of a digital image whose histogram does not allow for clear and easy differentiation between the features of interest and the background pixels, requires the use of an advanced thresholding algorithm. In our study two local, i.e. adaptive, thresholding procedures with various sizes of small picture regions (windows) were implemented on an image of a lab handsheet made of repulped coloured prints in order to accurately identify the location and the number of residual toner particles. One of the applied algorithms was based on the information maximization of the thresholded image while the other was a modified Niblack's method. Results of the study suggest that the latter method outperforms the former one when using a large window size. Information maximization algorithm typically fails to detect some lighter and coloured areas of objects of interest.

Keywords: Algorithms, image binarization, image processing, local thresholding

 
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