Title: Colour rendering: an object based approach
Authors: Smet, Kevin ×
Ryckaert, Wouter
Forment, Stefaan
Hertog, Wim
Deconinck, Geert
Hanselaer, Peter #
Issue Date: 2009
Publisher: CIE
Host Document: Light and Lighting Conference with Special Emphasis on LEDs and Solid State Lighting vol:x034:2009
Conference: Light and Lighting Conference with Special Emphasis on LEDs and Solid State Lighting location:Budapest, Hungary date:27-29 May 2009
Abstract: Light sources with limited spectral content cannot render colours correctly. Typical spectra of
phosphor white and RGB LEDs often result in a low colour rendering index, in spite of a high
appreciation of LED lighting in visual experiments. The standard approach to colour rendering
evaluation has always been based on a relative assessment: the colour coordinates of a set of
standards samples are compared with the colour coordinates under a reference illuminant. Our
work explores an alternative way for colour rendering evaluation based on an absolute evaluation
of the source. The basic idea is to do the referencing, not to an illuminant but to our visual
representation of a number of familiar objects. To this end a special viewing booth has been
constructed that allows a uniform LED illumination of non-planar surfaces. Specular reflection
must be avoided because this could reveal the colour of the illuminantion. Six Lamina RGB power
LEDs have been mounted around a diffusing tunnel in which the object is placed for observation.
Additionally, a large, internally lit, background screen provides a constant adaptation field to the
test subjects. In this way, changing the colour of the illumination is interpreted as a change in
colour of the object itself. An additional fixed external source provides a gloss effect which ensures
a natural look of the object. Preliminary visual experiments examining colour acceptance showed
good intra and inter observer rating variability, indicating the validity and feasibility of constructing
colour acceptance ellipsoids based on similarity with observer prototypical object colours.
Publication status: published
KU Leuven publication type: IC
Appears in Collections:ESAT - ELECTA, Electrical Energy Computer Architectures
Technologiecluster ESAT Elektrotechnische Engineering
Electrical Engineering (ESAT) TC, Technology Campuses Ghent and Aalst
× corresponding author
# (joint) last author

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