Green-Red Color Contrast Improvement
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Transcript of Green-Red Color Contrast Improvement
Green-Red Color Contrast Improvement: Feasibility, Effect and Interpretation
Dr. Katalin Tóth
GE Lighting
Global Lighting
Training & Six Sigma Manager
18 September
Same effect with artifictial illumination:
Standard CFL Reveal CFL
Booth testStandard FL 300lux Reveal ® 260 lux
Questions:
1, Which is more colourful2, Where are the contrasts sharper3, Where is the white brighter4, Where is the overall brightness higher
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Answer of 31 observers
Standard Reveal
Individual #1 9 12
Individual #2 16 18
Individual #3 13 21
Individual #4 18 20
Correct answers for Ishihara test
Standard FL 300lux Reveal® 260 lux
Pattern recognition of color deficient individuals
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:1 Inca. Std. FL_1 R Ⓡ
2 FL_2 R Ⓡ FL_1 RⓇ
3 FL Std FL_1 R Ⓡ4 FL Standard Inca. Reveal Ⓡ5 FL Standard Inca. Standard6 FL_2 Reveal Ⓡ Inca. Standard7 FL_2 Reveal Ⓡ FL Standard8 FL_2 Reveal Ⓡ Inca. Reveal Ⓡ9 FL_1 Reveal Ⓡ Inca. Reveal Ⓡ
10 Inca Standard Inca. Reveal Ⓡ
Y:Preference scores: right vs. left
-5 0 +5
Left onepreferred
Right onepreferred
Preference of Reveal®-likeperformance confirmed
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
Left lamp preferred
Right lamp preferred
NegligibleDifference
Current metrics for quality of light
Standard CFL Reveal®
Incandescent
Improved visual clarity Reveal® FL
Ra 80 78 72
R9 -12 14 23
LPW 65 13 60
Do they reflect perception test results?
Human photoreceptors
Rods:• Achromatic night vision• 1 type
Cones:• Daytime, achromatic and chromatic vision• 3 types
Long-wavelengthsensitive (L) or„red” cone
Middle-wavelength sensitive (M) or „green” cone
Short-wavelengthsensitive (S) or„blue” cone
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
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
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
Color is encoded by the relative cone outputs
Blue light Red light
Green light
Yellow light White light
Purple light
GE inside use only
Post receptorial color vision
M L M LS
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M-L
CRG
+
Trichomatic stage
Color opponent stage_
S-(M+L)
CBY
Chromaticpathways
GE inside use only
Type of color deficiency
CBY=S-(L+M) CRG= L-M
Neural opponent signals
Spectral response curves of cone cells
Trichomatic stage
Color opponent stage
GE inside use only
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By Katalin Toth/
September 27, 2012
Incandescent Lamps
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350 450 550 650 750Wavelength (nm)
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Fluorescent lamps
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Incandescent Reveal• filters out yellow (560-620nm)
Fluorescent spectrum: • minimizes addition of yellow
Looks like small change in spectrumSignificant effect in color perception
Reveal Performance
Warm white
Reveal®
TriphosTest#4
Reveal®
Standard
Emission spectra
GE inside use only
RG neural opponent signaladapted tostandard FL
GE inside use only
RG neural opponent signal adapted toReveal® FLResulting increased green-red contrast, gamut and better color rendering for red color
Protanomal’s RG neural opponent signal adapted to Reveal® FL
®
GE inside use only
21 /
By Katalin Toth/
September 27, 2012
CIE color-matching functions
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SPD*x-bar
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SPD of Inca.
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By Katalin Toth/
September 27, 2012
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SPD of Standard CFL
SPD of Reveal CFL
CIE color-matching functions
546 Hg line
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By Katalin Toth/
September 27, 2012
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
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By Katalin Toth/
September 27, 2012
Thank you for your attention!