Colour rendering of indoor lighting with CIE illuminants and white LEDs for normal and colour deficient observers

Abstract

The goal of this work was to evaluate the colour rendering of indoor lighting with CIE illuminants and white LEDs by estimating the chromatic diversity produced for normal and colour deficient observers. Reflectance spectra of a collection of scenes made of objects typically found indoors were obtained with hyperspectral imaging. Chromatic diversity was computed for 55 CIE illuminants and five LED light sources by estimating the number of different colours perceived in the scenes analysed. A considerable variation in chromatic diversity was found across illuminants, with the best producing about 50% more colours than the worst. For normal observers, the best illuminant was CIE FL3.8 which produced about 8% more colours than CIE illuminant A and D(65); for colour deficient observers, the best illuminants varied with the type of deficiency. When the number of colours produced with a specific illuminant was compared against its colour rendering index (CRI) and gamut area index (GAI), weak correlations were obtained. Together, these results suggest that normal and colour deficient observers may benefit from a careful choice of the illuminant, and this choice may not necessarily be based only on the CRI or GAI.

Color diversity index: the effect of chromatic adaptation

“…The use of the number of discernible colors as a viable descriptor of chromatic diversity of complex scenes was already studied 1,2 . In the particular case of daylight illuminants, the use of the chromatic adaptation obliterated the correlation between the Munsell set and the volume of natural scenes found in the former work.…”

“…The chromatic perception experienced in common everyday tasks can be dramatically influenced by the illumination selected [1][2][3][4] and therefore great care should be taken in the selection of a light source both for general and more specific tasks.…”

The Display Gamut Available to Simulate Colors Perceived by Anomalous Trichromats

“…Anomalous trichromats observers still retain the functional use of the three color sensors, but their spectral sensitivity by the means of a pigment that is photosensitive to visible light is different from the normal color vision observer on the M and L cones [3], [4] and are named deuteroanomalous and protoanomalous, respectively. The differences in the spectral sensitivity of anomalous observers will impair their color vision [5], [6] and might limit their ability to perform some tasks [7]. This limitation is found to be the confusion of some colors that are identified as different by normal color vision observers with a direct impact on color vision perception [8], [9].…”

Effects of high-color-discrimination capability spectra on color-deficient vision

“…This volume was estimated for each scene by segmenting the corresponding CIELAB color volume into cubes of unitary side and by counting the number of nonempty cubes. The images were generated from hyperspectral data acquired in the range of 400-720 nm at 10 nm intervals and later interpolated to 5 nm steps to better adjust the hyperspectral data to the spectral profile of the illuminants (for details on the spectral imaging technique, see [25]). …”

“…These triband light sources were considered to enhance color discrimination for the normal color observer, and it was suggested [7] that it may be expected that they do the same for color-deficient observers. Studies based on standard illuminants [24,25] and on the effects of colored filters [26] suggest that some spiky spectra may in fact improve color discrimination for some classes of color-deficient observers, but the spectra with high-color-discrimination capability were not yet systematically tested.…”