Dr. Katalin Toth's presentation about the green-red colour contrast improvement at the conference Strategies in Light Europe 2012 in MÜnchen, Germany.

1. Green-Red Color Contrast Improvement:
Feasibility, Effect and Interpretation
Dr. Katalin Tóth
GE Lighting
Global Lighting
Training & Six Sigma Manager
18 September

2. Same effect with artifictial illumination:

3. Standard CFL Reveal CFL

4. Booth test
Standard FL 300lux Reveal ® 260 lux
35
Questions: Answer of 31 observers
30
1, Which is more colourful 25
2, Where are the contrasts sharper 20
1 booth
3, Where is the white brighter
15 2 booth
4, Where is the overall brightness higher
10
5
0
1 2 3 4

5. Pattern recognition of color deficient individuals
Standard FL 300lux Reveal® 260 lux
Correct answers for Ishihara test
Standard Reveal
Individual #1 9 12
Individual #2 16 18
Individual #3 13 21
Individual #4 18 20

6. Human Perception
• 2 booths
• 3 images
• 26 individuals
• Luminance set equal in both booths
• Compare right lamp with left lamp
• Difference was calibrated to the Inc-Reveal pair.
Lamp pairs tested: Y:
1 Inca. Std. FL_1 R Ⓡ Preference scores: right vs. left
2 FL_2 R Ⓡ FL_1 RⓇ
3 FL Std FL_1 R Ⓡ
4 FL Standard Inca. Reveal Ⓡ
5 FL Standard Inca. Standard
Left one Right one
6 FL_2 Reveal Ⓡ Inca. Standard preferred preferred
7 FL_2 Reveal Ⓡ FL Standard
8 FL_2 Reveal Ⓡ Inca. Reveal Ⓡ -5 0 +5
9 FL_1 Reveal Ⓡ Inca. Reveal Ⓡ
10 Inca Standard Inca. Reveal Ⓡ

7. Preference of Reveal®-like
performance confirmed
Left lamp Negligible Right lamp
preferred Difference preferred
Individual 95% CI
Pair Mean --------+---------+---------+---------+---
1 Inc Std. FL_1 RⓇ 0.577 (--*---)
2 FL_2 R Ⓡ FL_1 RⓇ-0.000 (---*---)
3 FL Std. FL_1 RⓇ 0.654 (--*---)
4 FL Std. Inc. RⓇ 0.679 (---*---)
5 FL Std. Inc. Std.-0.103 (--*---)
6 FL_2 RⓇ Inc. Std.-0.551 (--*---)
7 FL_2 RⓇ FL Std. -0.526 (---*--)
8 FL_2 RⓇ Inc. RⓇ -0.026 (--*---)
9 FL_1 RⓇ Inc. RⓇ 0.051 (--*---)
10 Inc. Std. Inc. RⓇ 0.808 (--*---)
--------+---------+---------+---------+---
-0.400 0.000 0.400 0.800

8. Current metrics for quality of light
Standard CFL Reveal® Improved visual
Incandescent clarity Reveal® FL
Ra 80 78 72
R9 -12 14 23
LPW 65 13 60
Do they reflect perception test results?

9. Human photoreceptors
Rods:
• Achromatic night vision
• 1 type
Cones:
• Daytime, achromatic and
chromatic vision
• 3 types
Long-wavelength Middle-wavelength Short-wavelength
sensitive (L) or sensitive (M) or sensitive (S) or
„red” cone „green” cone „blue” cone

10. Why do we have rods and cones
Our vision has to operate over an enormous range of
1012 levels
To cover that range we have two different types of photoreceptors:
• Rods that are optimized for low light levels
• Cones that are optimized for higher light levels
GE inside use only

11. Rod and cone distribution
• 0.3mm of eccentricity is about 1 deg of visual angle (eccentricity angle)
• 120 million rods (absent in the central of fovea (0.3mm fovea centralis), max at 20 deg
• At night you have to look away from things to see them in more details
• 6-7 million cones (concentrated in the fovea)
• During the day you have to look at things directly to see them in detail
GE inside use only

12. Spectral sensitivity, univariance
• Probability of photon absorption depends upon wavelength
• But response is independent of photon wavelength
• Change in output could be caused by change in intensity or a change in color
• Each photoreceptor is „color blind”, being unable to distinguish between colour and
intensity changes
• All the photoreceptor effectively does is to count photons
GE inside use only

13. Color is encoded by the relative cone outputs
Blue light Red light
Green light Purple light
Yellow light White light
GE inside use only

14. Post receptorial color vision
M L S M L
Trichomatic stage
_
+
_ Color opponent stage
M-L S-(M+L)
CRG CBY
Chromatic
pathways
GE inside use only

15. Type of color deficiency

16. Trichomatic stage
Spectral response curves of cone cells
Color opponent stage
CBY=S-(L+M) CRG= L-M
Neural opponent signals
GE inside use only

17. Reveal Performance
Incandescent Lamps
1.00
0.90
0.80
Relative intensity
0.70
0.60
0.50
0.40
Warm white Incandescent Reveal
0.30 Reveal® • filters out yellow (560-620nm)
0.20
0.10
0.00
350 450 550 650 750
Wavelength (nm)
Fluorescent lamps
1.0
0.9
0.8
Fluorescent spectrum:
Relative Intensity
0.7 Triphos
0.6 Test#4
0.5 • minimizes addition of yellow
0.4
0.3 Looks like small change in spectrum
0.2
0.1
Significant effect in color perception
0.0 17 /
350 450 550 650 750 By Katalin Toth/
Wavelength (nm) September 27, 2012

18. Emission spectra
Reveal®
Standard
GE inside use only

19. RG neural opponent signal
adapted to
standard FL
RG neural opponent signal
adapted to
Reveal® FL
Resulting increased green-red
contrast, gamut and better
color rendering for red color
GE inside use only

20. Protanomal’s RG neural opponent signal
adapted to Reveal® FL
®
GE inside use only

21. 30
SPD of 25
Inca. 20
CIE color-matching 15
SPD*x-bar
SPD*y-bar
functions
2
SPD*z-bar
10
1.8
1.6 5
1.4
0
380
399
418
437
456
475
494
513
532
551
570
589
608
627
646
665
684
703
722
741
760
1.2
x-bar
1 y-bar
z-bar
0.8
0.6
0.4 25
0.2
0 20
380
399
418
437
456
475
494
513
532
551
570
589
608
627
646
665
684
703
722
741
760
15
SPD*x-bar
SPD*y-bar
10 SPD*z-bar
5
SPD of Reveal Incan .0
21 /
380
399
418
437
456
475
494
513
532
551
570
589
608
627
646
665
684
703
722
741
760
By Katalin Toth/
September 27, 2012

22. 400
350
300
SPD of Standard CFL 250
SPD*x-bar
200
SPD*y-bar
SPD*z-bar
150
100
CIE color-matching functions 50
2
0
1.8
380
400
420
440
460
480
500
520
540
560
580
600
620
640
660
680
700
720
740
760
1.6
1.4
1.2
x-bar
1 y-bar
z-bar
0.8 0.2
0.6
0.18
0.4
0.16
0.2
0 0.14
380
399
418
437
456
475
494
513
532
551
570
589
608
627
646
665
684
703
722
741
760
0.12
SPD*x-bar
0.1
SPD*y-bar
0.08 SPD*z-bar
0.06
546 Hg line
0.04
0.02
SPD of Reveal CFL 0 22 /
380
400
420
440
460
480
500
520
540
560
580
600
620
640
660
680
700
720
740
760
By Katalin Toth/
September 27, 2012

23. Color contrast improvement summary:
• Make colour more vivid: increased chroma
• Improve green-red contrast
• Good for person with certain type colour-
deficiency
• Increase perceived illumination level
23 /
By Katalin Toth/
September 27, 2012

24. Thank you for your attention!
24 /
By Katalin Toth/
September 27, 2012