LEDs experiments in Paris 1. Colour rendering 2. Kruithof’s rule. F. Viénot, E. Mahler, A. Rambaud, M.-L. Durand, C. Boust, J.-J. Ezrati, CRCC, Muséum national d’histoire naturelle CIE, TC1-69, Stockholm, June 2008. Colour rendering - Illumination. WWARGB. WR. RGBA. RGB. LED clusters
F. Viénot, E. Mahler, A. Rambaud, M.-L. Durand, C. Boust, J.-J. Ezrati,
CRCC, Muséum national d’histoire naturelle
CIE, TC1-69, Stockholm, June 2008
RGB LEDs “RGB”
RGB+Amber LEDs “RGBA”
two-phosphor cold white LED + Red LED “WR”
two-phosphor cold white LED + two-phosphor warm white LED + Amber + RGB LEDs “WWARGB”
Distribution of colourfulness ratings
Distribution of hues
Solux WWRGBA RGB
Rea Mark S., Freyssinier-Nova Jean P., 2008, Color Rendering: A Tale of Two Metrics, COLOR research and application, 33: 192-202.
Kruithof, A. A.: Tubular Luminescence Lamps for General Illumination, Philips Technical Review 6, pp. 65-96 (1941).
Kruithof has examined the illuminance limits between which users find the illumination “pleasant”.
Kruithof’s diagram (Fig. 10) shows the accepted combination of illuminance and colour temperature.
The author states that, globally, a low and high illumination should correspond to a low and high colour temperature, respectively (my translation).
Illuminance (log scale)
Correlated colour temperature
low-contrast acuity (log)
Y in cd.m-2
Perceived lightness scale
Y in cd.m-2