leds experiments in paris 1. colour rendering 2. kruithofs rule f. viénot, e. mahler, a. rambaud,...
TRANSCRIPT
LEDs experiments in Paris
1. Colour rendering2. 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
• LED clustersRGB 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”
• Control light : Solux filtered tungsten-halogen lamp
WWARGB
0
0.01
0.02
380 480 580 680 780
Wavelength [nm]
Spe
ctra
l irra
dian
ce (W
/m2)
WWARGBWR
0
0.01
0.02
380 480 580 680 780
Wavelength [nm]
Spe
ctra
l irr
adia
nce
(W/m
2)
WRRGBA
0
0.01
0.02
0.03
380 480 580 680 780
Wavelength [nm]
Spe
ctra
l irra
dian
ce (W
/m2)
RGBARGB
0
0.01
0.02
0.03
0.04
0.05
0.06
380 480 580 680 780
Wavelength [nm]
Spe
ctra
l irr
adia
nce
(W/m
2)
RGB Solux
0
0.01
0.02
380 480 580 680 780
Wavelength [nm]
Spe
ctra
l irr
adia
nce
(W/m
2)
Solux
Colour rendering - Discrimination
• Distribution of errors
Errors of neighbourhood of each cap
0
1
2
3
4
5
6
7
8
9
10
1 4 7 10 13 16 19 22 25 28 31
32 caps
Nu
mb
er
of
err
ors
of
ne
igh
bo
urh
oo
d
Solux WWARGB WR RGBA RGB
RGB
Solux
Colour rendering - Appearance
• Distribution of colourfulness ratings • Distribution of hues
Col
ourf
ulne
ss r
atin
g
Visual appearance experiment
0
1
2
3
4
5
6
7
8
9
10
R Y50R Y G50Y G B50G B R50B R
NCS sample code
Obs
erv
ers
ratin
g
Solux
RGB
RGBA
WR
WWARGB
RGB
Red-BlueRed-BlueRed-BlueR10B
Red-BlueRed-BlueRed-BlueR20B
Red-BlueRed-BlueRed-BlueR30B
Red-BlueRed-BlueRed-BlueR40B
Blue-RedRed-BlueBlue-RedR50B
Blue-RedBlue-RedBlue-RedR60B
Blue-RedBlue-RedBlue-RedR70B
Blue-GreenBlue-RedBlue-RedR80B
Blue-GreenBlue-RedBlue-RedR90B
Blue-GreenBlue-GreenBlue-GreenB
Blue-GreenBlue-GreenBlue-GreenB10G
manquantmanquantmanquantB20G
Blue-GreenBlue-GreenBlue-GreenB30G
Green-BlueBlue-GreenBlue-GreenB40G
Green-BlueBlue-GreenBlue-GreenB50G
Green-BlueBlue-GreenBlue-GreenB60G
Green-BlueGreen-BlueBlue-GreenB70G
manquantmanquantmanquantB80G
Green-BlueGreen-BlueGreen-BlueB90G
Green-BlueGreen-YellowGreen-BlueG
Green-BlueGreen-BlueGreen-YellowG10Y
Green-YellowGreen-YellowGreen-YellowG20Y
Green-YellowGreen-YellowGreen-YellowG30Y
Green-YellowGreen-YellowGreen-YellowG40Y
Green-YellowYellow-GreenYellow-GreenG50Y
Green-YellowYellow-GreenGreen-YellowG60Y
Yellow-GreenYellow-GreenYellow-GreenG70Y
Yellow-GreenYellow-GreenYellow-GreenG80Y
Yellow-GreenYellow-GreenYellow-GreenG90Y
Yellow-RedYellow-RedYellow-RedY
Yellow-RedYellow-RedYellow-RedY10R
Yellow-RedYellow-RedYellow-RedY20R
Red-YellowYellow-RedRed-YellowY30R
Red-YellowYellow-RedRed-YellowY40R
Red-YellowRed-YellowRed-YellowY50R
Red-YellowRed-YellowRed-YellowY60R
Red-YellowRed-YellowRed-YellowY70R
Red-YellowRed-YellowRed-YellowY80R
Red-YellowRed-YellowRed-YellowY90R
Red-YellowRed-YellowRed-YellowR
RGBWWARGBSoluxNCS
Red-BlueRed-BlueRed-BlueR10B
Red-BlueRed-BlueRed-BlueR20B
Red-BlueRed-BlueRed-BlueR30B
Red-BlueRed-BlueRed-BlueR40B
Blue-RedRed-BlueBlue-RedR50B
Blue-RedBlue-RedBlue-RedR60B
Blue-RedBlue-RedBlue-RedR70B
Blue-GreenBlue-RedBlue-RedR80B
Blue-GreenBlue-RedBlue-RedR90B
Blue-GreenBlue-GreenBlue-GreenB
Blue-GreenBlue-GreenBlue-GreenB10G
manquantmanquantmanquantB20G
Blue-GreenBlue-GreenBlue-GreenB30G
Green-BlueBlue-GreenBlue-GreenB40G
Green-BlueBlue-GreenBlue-GreenB50G
Green-BlueBlue-GreenBlue-GreenB60G
Green-BlueGreen-BlueBlue-GreenB70G
manquantmanquantmanquantB80G
Green-BlueGreen-BlueGreen-BlueB90G
Green-BlueGreen-YellowGreen-BlueG
Green-BlueGreen-BlueGreen-YellowG10Y
Green-YellowGreen-YellowGreen-YellowG20Y
Green-YellowGreen-YellowGreen-YellowG30Y
Green-YellowGreen-YellowGreen-YellowG40Y
Green-YellowYellow-GreenYellow-GreenG50Y
Green-YellowYellow-GreenGreen-YellowG60Y
Yellow-GreenYellow-GreenYellow-GreenG70Y
Yellow-GreenYellow-GreenYellow-GreenG80Y
Yellow-GreenYellow-GreenYellow-GreenG90Y
Yellow-RedYellow-RedYellow-RedY
Yellow-RedYellow-RedYellow-RedY10R
Yellow-RedYellow-RedYellow-RedY20R
Red-YellowYellow-RedRed-YellowY30R
Red-YellowYellow-RedRed-YellowY40R
Red-YellowRed-YellowRed-YellowY50R
Red-YellowRed-YellowRed-YellowY60R
Red-YellowRed-YellowRed-YellowY70R
Red-YellowRed-YellowRed-YellowY80R
Red-YellowRed-YellowRed-YellowY90R
Red-YellowRed-YellowRed-YellowR
RGBWWARGBSoluxNCS
Solux WWRGBA RGB
<- Red
<- Yellow
<- Green
<- Blue
<- Red
Red ->
Yellow ->
Green ->
Blue ->
Red ->
Colour rendering - Conclusion
• Colour rendering– either Colour fidelity, colour discrimination– or Colourfulness enhancement
• Different tasks and different visual coding• Results of thiese experiments can be
predicted from CIELAB or CIECAM02
• Agreement withRea Mark S., Freyssinier-Nova Jean P., 2008, Color Rendering: A Tale
of Two Metrics, COLOR research and application, 33: 192-202.
Kruithof’s rule - Background
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).Ill
umin
ance
(lo
g sc
ale)
Correlated colour temperature
Re-examination of Kruithof’s ruleObjectives
• Since LED illumination is very flexible in terms of luminous intensity and colour temperature, we have planned an experiment to re-examine this rule, questioning the interpretation and the physiological basis of the “pleasantness” sensation.
• Collaborators– Marie-Lucie Durand, Paris-Orsay University– Elodie Mahler, SNCF, France
Re-examination of Kruithof’s rule Methods
• Light booth equipped with LEDs (cool white, warm white, orange, amber, green, cyan, blue)
• Illuminance : 150, 300 and 600 lx• Correlated colour temperature : 2700, 4000,
6500 K• Optimised CRI > 86
Re-examination of Kruithof’s rule Tasks
• Three type of tasks– Performance (acuity, contrast threshold, reading)– Color perception (hue appearance, colour preference,
cognitive colours)– Subjective feeling (pleasantness, mood, …)
• Methods (depending upon the task)– Scaling, ranking, thresholds, category scaling,
semantic analysis, ANOVA
• 30 young observers
Re-examination of Kruithof’s rule Performance
• Example of low-contrast acuity
IlluminationsY in cd.m-2lo
w-c
ontr
ast
acui
ty (
log)
Re-examination of Kruithof’s rule Colour appearance
• Example of location of binary hues
Re-examination of Kruithof’s rule Sensation scale
• Example of lightness sensation
IlluminationsY in cd.m-2
Pe
rce
ive
d li
ghtn
ess
sca
le