More info
Description / Abstract:
This Technical Report reviews the applicability of the CIE
colour rendering index to white LED light sources based on the
results of visual experiments. The currently recommended colour
rendering index (CRI) calculation method was officially introduced
in 1974, and is described in the current publication CIE 13.3-1995
(CIE, 1995). Visual experience has shown that the current CRI based
ranking of a set of light sources containing white LED light
sources contradicts the visual ranking.
In this Technical Report, three recent visual experiments
(including simulations) on colour rendering including white LED
light sources are described that confirm this contradiction. It was
concluded from these visual colour rendering results that the
current CRI method did not describe well those situations where
white LED light sources were involved i.e. if white LED light
sources were visually ranked together with other light sources. Low
correlation was found between the visual colour differences and the
computed colour differences if the current CRI method was applied
to calculate those colour differences. The conclusion of the
Technical Committee is that the CIE CRI is generally not applicable
to predict the colour rendering rank order of a set of light
sources when white LED light sources are involved in this set.
The Committee recommends the development of a new colour
rendering index (or a set of new colour rendering indices) by a
Division 1 Technical Committee. This index (or these indices) shall
not replace the current CIE colour rendering index immediately. The
usage of the new index or indices should provide information
supplementary to the current CIE CRI, and replacement of CRI will
be considered after successful integration of the new index. The
new supplementary colour rendering index (or set of supplementary
colour rendering indices) should be applicable to all types of
light sources and not only to white LED light sources.
Possibilities for an improved description of colour rendering are
summarized in the Appendix of this Technical Report.