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Journal article 943 views

A multi colour separation system for graphic images

Eifion Jewell Orcid Logo

Journal of Print Media Technology and Research., Volume: 1, Issue: 4

Swansea University Author: Eifion Jewell Orcid Logo

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Abstract

This paper reports on the development of a six colour separation system for the rendition of multi coloured images. An algorithm is described which can be used for 6 colour separation of complex photographic images in order to maximise image gamut. Using a custom set of 6 colours a Yule Nielsen modi...

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Published in: Journal of Print Media Technology and Research.
ISSN: ISSN 2223-8905
Published: 2013
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa37707
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Abstract: This paper reports on the development of a six colour separation system for the rendition of multi coloured images. An algorithm is described which can be used for 6 colour separation of complex photographic images in order to maximise image gamut. Using a custom set of 6 colours a Yule Nielsen modified Neugerbauer equation is used to produce a colour model to predict colour mixing using 65 Neugerbauer primaries. Over 60% of the model predictions were within a E of 5. Some larger errors could be associated with the optical brighteners in the paper substrate. This model was considered sufficiently accurate for the basis of a colour separation model. To reduce computational effort at the separation stage a 243 pure lookup table was created to store the results of the colour model. This table creation is computationally heavy at the table creation stage, but fast for the user. The “one to many” mapping from XYZ to 6 colourants was dealt with by enabling a rule based system and a smoothing function. The rule based system is based on practical printing issues which would be could be experienced on press. To incorporate the possibility of a black separation for some dark images, a system was developed where the “in gamut” of any image is calculated in order to maximise output colour gamut. The system can be adapted for an increased number of base colourants.
Keywords: Colour separation.
College: Faculty of Science and Engineering
Issue: 4