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.
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
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
| Title | Version | Date | File type | Download |
|---|---|---|---|---|
| Consistent colour appearance - A novel measurement approach | 22.10.2019 | Download | ||
| CIC 2019 Presentation | 23.09.2020 | Download |