Topic of your interest

Consistent Colour Appearance - Devolopment of a method for evaluating colour reproductions via different output channels

Short name: CCA (Consistent Colour Appearance)

Fogra no. 10.059
Project leader: Dr M. Mattuschka
Funding: BMWi (IGF) via AiF 
 

Timescale: 1.3.2017 - 28.2.2019

Objective and relevance

Consistent Colour Appearance (CCA) extends the established visual assessment of two colour originals to include applications where several reproductions of an original are viewed simultaneously. Between different reproductions of an original over several output channels, a consistent colour appearance is present if the direct comparison of these images with each other is perceived by an observer as coherent or consistent.

In this project it is shown that a uniform colour appearance is statistically significant, i.e. measurable. To this end, 80 test persons in 120 experiments using test print and monitor proof (soft proof) compare seven different strategies with regard to their “uniformity”. The evaluation of the psychophysical pair comparison experiments shows a “winner group” with three strategies, a significantly different midfield with three strategies and one loser. A significant agreement of the assessments of all test subjects is found.

Dr Marco Mattuschka

Prepress Technology

+49 89 431 82 - 334

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Solution steps

Since established methods for determining colour distances cannot be detected for the extra large (supra threshold) colour distances caused by the different output colour spaces, a metric based on exceeded (English) colour names will be developed. Specifically, the colour centres are determined by means of Voronoi decomposition. For the calculation of the number of crossed colour names between two colour locations (LAB values) the curve length is calculated. The possible density functions are optimized with regard to the best possible correlation with the previously determined observer responses.

Research results

A new metric was developed based on crossed (English) colour names. To calculate the number of exceeded colour names between two colour locations (LAB values) the curve length is calculated. This method is available as a web-based tool for individual colours ("Spot-Mode") as well as on the basis of the established Fogra MediaWedge (as a RGB-version) for free application. 

Webtool

On the initiative of Fogra, the CIE Working Group 8-16 “Consistency of Colour Appearance within a Single Reproduction Medium” was established. It now brings together international colour researchers in this new field of colour science.

Meeting documents & Downloads