evaluating light source color rendition using ies tm-30-15...sep 07, 2016 · tcs 01 tcs 02 tcs 03...
TRANSCRIPT
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Evaluating Light Source Color
Rendition using IES TM-30-15
Kevin W. Houser, PhD, PE, FIES, LCProfessor of Architectural Engineering Editor-in-Chief
The Pennsylvania State University LEUKOS, the journal of IES
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Which do you prefer?
Ra (CRI)= 50
R9 = -80
CCT = 3501 K
Duv = 0.0000
Ra (CRI)= 75
R9 = 20
CCT = 3501 K
Duv = 0.0000
1 2
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Today’s Outline
Brief overview of CIE CRI
Introduction to TM-30-15 IES Method for
Evaluating Light Source Color Rendition
Demonstration
Resources
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Today’s Outline
Brief overview of CIE CRI
Introduction to TM-30-15 IES Method for
Evaluating Light Source Color Rendition
Demonstration
Resources
-
CIE CRI (Ra)
SAME CCT
Test SourceReference Illuminant
(approximately)
For further reading see CIE 13.3-1995, or Houser K, Mossman M, Smet K, Whitehead L. 2015. Tutorial: Color Rendering and Its Applications in Lighting. LEUKOS. http://dx.doi.org/10.1080/15502724.2014.989802
http://dx.doi.org/10.1080/15502724.2014.989802
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CIE CRI (Ra)
TCS 01 TCS 02 TCS 03 TCS 04
TCS 05 TCS 06 TCS 07 TCS 08
Approximation of Color Samples for Ra
TCS 09 TCS 10 TCS 11 TCS 12
TCS 13 TCS 14
Color Samples for R9–R14
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CIE CRI (Ra)
(Illustration Only)
R Y GY G BG PB P RP
U*
V*
-10
-20
+20
+10
-10-20 +20+10+30 +30
GY
BG
Y
PB
R
RP
P
G
-
CIE CRI (Ra)
(Illustration Only)
R Y GY G BG PB P RP
U*
V*
-10
-20
+20
+10
-10-20 +20+10+30 +30
GY
BG
Y
PB
R
RP
P
G
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CIE Method for Color Rendering
Color Fidelity
CIE CRI (Ra)
The accurate rendition of
color so that they appear as
they would under familiar
(reference) illuminants
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Original Image courtesy of Randy Burkett Lighting Design
CRI = 95, Original Image
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Original Image courtesy of Randy Burkett Lighting Design
CRI = 80, Desaturated Image
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Original Image courtesy of Randy Burkett Lighting Design
CRI = 80, Saturated Image (Red Enhanced)
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“Original” Baseline
Original image courtesy of Randy
Burkett Lighting Design
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“CRI = 80” - Hue Shift
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“CRI = 80” + Hue Shift
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“CRI = 80” Saturated
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“CRI = 80” Desaturated
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Limitations of Considering Only Fidelity
Perfect Fidelity
Increase
Saturation
Decrease
Saturation
Positive Hue Shift
Negative Hue Shift
CRI = 80 CRI = 80
Constant CIE CRI
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Perfect Fidelity
Increase
Saturation
Decrease
Saturation
Positive Hue Shift
Negative Hue Shift
CRI = 80 CRI = 80
Constant CRI
One measure is not enough!
Limitations of Considering Only Fidelity
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Today’s Outline
Brief overview of CIE CRI
Introduction to TM-30-15 IES Method for
Evaluating Light Source Color Rendition
Demonstration
Resources
-
Two primary motivations for developing the
IES Method:
1. The need for an improved measure of color
fidelity
2. The need to provide supplementary informationabout color rendering ability of any given light source
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Fidelity Index (Rf)
Gamut Index (Rg)
High Level Average Values
Core Calculation Engine
Modern Color Science
New Color Samples
Color Vector Graphic
Color Distortion Graphic
Graphical Representations
Skin Fidelity (Rf,skin)
Fidelity by Hue (Rf#)
Chroma Shift by Hue (Rc#)
Fidelity by Sample (Rf,CES#)
Detailed Values
IES Method for Color Rendition
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Color Fidelity
Fidelity Index (Rf)
IES Method for Color Rendition
The accurate rendition
of color so that they
appear as they would
under familiar
(reference) illuminants
Color Gamut
The average level of
saturation relative to
familiar (reference)
illuminants.
Gamut Index (Rg)
(0-100)
~60-140 when Rf > 60
Graphics
Visual description of
hue and saturation
changes.
Color Vector Graphic
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• Quantifies average similarity in appearance of test and reference sources
• Analogous to CIE Ra, but more accurate
• Scores of 0 to 100• Scale similar to CIE Ra, but high scores
harder to achieve• Equal weight to all directions of shift• Should not be expected to correlate
with any single object color
Fidelity Index: Rf
[Flattened to 2D]
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40
b'
a' Reference Source Test Source
-
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40
b'
a' Reference Source Test Source
1
2
16
15
8
7
9
10
3456
14131211-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40b
'a'
Reference Source Test Source
1
2
16
15
8
7
9
10
3456
14131211
Relative Gamut Index: Rg
-
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40b
'a'
Reference Source Test Source
1
2
16
15
8
7
9
10
3456
14131211
𝑅𝑔 = 100 ×𝐴𝑡𝐴𝑟
Rg > 100: Average increase in saturation
Rg < 100: Average decrease in saturation
Relative Gamut Index: Rg
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Original Desaturated Red-Enhanced
CRI = 95 CRI = 80 CRI = 80
Theoretical Example
Rf = 93 Rf = 78 Rf = 78
Rg = 100 Rg = 90 Rg = 110
Original Image courtesy of Randy Burkett Lighting Design
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Original Desaturated Red-Enhanced
CRI = 95 CRI = 80 CRI = 80
Theoretical Example
Rf = 93 Rf = 78 Rf = 78
Rg = 100 Rg = 90 Rg = 110
Image courtesy of Randy Burkett Lighting Design
Average values can hide
important information!
This is limitation of CIE Ra,
and IES Rf and Rg
-
380 430 480 530 580 630 680 730 780
Rf = 81Rg = 101CCT = 2496 KRa = 88
(Source No. 286)
“Gamut” is not a dimension of perception. It is best interpreted with reference to a complementary graphic.
Color Vector Graphic
Color Vector Graphic
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COLOR VECTOR GRAPHIC
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40b
'a'
Reference Source Test Source
CES CHROMATICITY COMPARISON
1
2
16
15
8
7
9
10
3456
14131211
Color Vector Graphic
-
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40b
'a'
Reference Source Test Source
CES CHROMATICITY COMPARISON
1
2
16
15
8
7
9
10
3456
14131211
Color Vector Graphic
-
-40
-30
-20
-10
0
10
20
30
40
-40 -30 -20 -10 0 10 20 30 40b
'a'
Reference Source Test Source
CES CHROMATICITY COMPARISON
1
2
16
15
8
7
9
10
3456
14131211
Decreased Saturation
Hue Shift
IncreasedSaturation
Color Vector Graphic
-
Original Desaturated Red-Enhanced
Theoretical Example
Original Desaturated Red-Enhanced
CRI = 95 CRI = 80 CRI = 80
Rf = 93 Rf = 78 Rf = 78
Rg = 100 Rg = 90 Rg = 110
Original Image courtesy of Randy Burkett Lighting Design
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Today’s Outline
Brief overview of CIE CRI
Introduction to TM-30-15 IES Method for
Evaluating Light Source Color Rendition
Demonstration
Resources
-
7
-
1
-
2
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32 versus 3Comparable
CIE Ra and R9
-
4
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55 versus 4
Case 4 is eleven
points higher in
CRI (83 vs. 72)
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65 versus 6
Case 6 is eight
points higher in
CRI (80 vs. 72)
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7
-
Today’s Outline
Brief overview of CIE CRI
Introduction to TM-30-15 IES Method for
Evaluating Light Source Color Rendition
Demonstration
Resources
-
IES Technical Memorandum (TM) 30-15 (Includes Excel Calculators):
IES Method for Evaluating Light Source Color Rendition
http://bit.ly/1IWZxVu
Optics Express journal article that provides overview of the IES method:
Development of the IES method for evaluating the color rendition of light sources
http://bit.ly/1J32ftZ
LEUKOS article supporting TM-30’s technical foundations:
Smet KAG, David A, Whitehead L. 2015. Why Color Space and Spectral Uniformity Are Essential for Color
Rendering Measures. LEUKOS. 12(1,2):39-50.
http://dx.doi.org/10.1080/15502724.2015.1091356
Lighting Research and Technology, Open Letter:
Correspondence: In support of the IES method of evaluating light source colour rendition
(More than 30 authors)
http://dx.doi.org/10.1177/1477153515617392
Lighting Research and Technology article showing applicability of TM-30-15 to human perceptions:
Royer MP, Wilkerson A, Wei M, Houser K, Davis R. 2016. Human perceptions of colour rendition vary with
average fidelity, average gamut, and gamut shape. Online before print
http://dx.doi.org/10.1177/1477153516663615
Application webinar co-sponsored by US Department of Energy and Illuminating Engineering Society:
Understanding and Applying TM-30-15: IES Method for Evaluating Light Source Color Rendition
http://1.usa.gov/1YEkbBZ
Technical webinar co-sponsored by US Department of Energy and Illuminating Engineering Society:
A Technical Discussion of TM-30-15: Why and How it Advances Color Rendition Metrics
http://1.usa.gov/1Mn15LG
DOE Fact Sheet on TM-30
http://energy.gov/eere/ssl/downloads/evaluating-color-rendition-using-ies-tm-30-15
DOE TM-30 FAQs Page:
http://energy.gov/eere/ssl/tm-30-frequently-asked-questions
IES
Journals
US DOE
http://bit.ly/1IWZxVuhttp://bit.ly/1J32ftZhttp://dx.doi.org/10.1080/15502724.2015.1091356http://dx.doi.org/10.1177/1477153515617392http://dx.doi.org/10.1177/1477153516663615http://1.usa.gov/1YEkbBZhttp://1.usa.gov/1Mn15LGhttp://energy.gov/eere/ssl/downloads/evaluating-color-rendition-using-ies-tm-30-15http://energy.gov/eere/ssl/tm-30-frequently-asked-questions
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46
These slides are available to download:
http://www.personal.psu.edu/kwh101/LysetsDag2016/main.htm
Or
http://bit.ly/2cq0NG4
http://www.personal.psu.edu/kwh101/LysetsDag2016/main.htmhttp://bit.ly/2cq0NG4
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Bonus Slides
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Human Judgements of Color Rendition Vary with Average Fidelity, Average Gamut, and Gamut ShapeLighting Research & Technology: http://dx.doi.org/10.1177/1477153516663615
Michael Royer, Pacific Northwest National LaboratoryAndrea Wilkerson, Pacific Northwest National LaboratoryMinchen Wei, Hong Kong Polytechnic UniversityKevin Houser, Penn State UniversityRobert Davis, Pacific Northwest National Laboratory
Funding• Royer, Wilkerson, and Davis supported by U.S. Department of Energy Laboratory
Directed Research and Development (LDRD) award• Houser subcontracted by Pacific Northwest National Laboratory.• Wei supported by Penn State, with later stages supported by Hong Kong
Polytechnic.
Goals Hypotheses Methods ConclusionsDiscussionResults
http://dx.doi.org/10.1177/1477153516663615
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a priori hypotheses
1. As Rf increases, color would be
judged as more normal.
2. As Rg increases, color would be
judged as more saturated.
3. Higher levels of Rg would be
more preferred than lower levels
of Rg.
4. Higher levels of red saturation
would be preferred.
Goals Hypotheses Methods ConclusionsDiscussionResults
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Apparatus and Test Space
Goals Hypotheses Methods ConclusionsDiscussionResults
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Independent Variables: Rf, Rg, and Gamut Shape
26
10
2
2
4
6
8
10
12
14
16
18
20
22
23
26
70
80
90
100
110
120
130
60 70 80 90 100
Rf
Rg
Goals Hypotheses Methods ConclusionsDiscussionResults
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2
4
6
8
10
12
14
16
18
20
22
23
26
70
80
90
100
110
120
130
60 70 80 90 100
19
1
3
5
7
9
11
13
15
17
21
24
25
Rf
Rg
Independent Variables: Rf, Rg, and Gamut Shape
Goals Hypotheses Methods ConclusionsDiscussionResults
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13
14
14
70
80
90
100
110
120
130
60 70 80 90 100
13
Rf
Rg
Independent Variables: Rf, Rg, and Gamut Shape
Goals Hypotheses Methods ConclusionsDiscussionResults
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26
-
10
-
1
-
70
80
90
100
110
120
130
60 70 80 90 100
IES
TM-3
0 R
g
IES TM-30 Rf
1
2 3
Goals Hypotheses Methods ConclusionsDiscussionResults
Preference varied systematically.Higher levels of Rg were generally preferred to lower levels of Rg.
a priori hypotheses
3. Higher levels of Rg
would be more
preferred than lower
levels of Rg.
4. Higher levels of red
saturation would be
preferred.
Dislike
Like
5.5
5.0
4.5
4.0
-
1 2 3
(These aren’t necessarily the most preferred sources possible, just the most preferred sources from this experiment).
Goals Hypotheses Methods ConclusionsDiscussionResults
Preference varied systematically.Higher levels red saturation were preferred.
-
70
80
90
100
110
120
130
60 70 80 90 100
IES
TM-3
0 R
g
IES TM-30 Rf
Goals Hypotheses Methods ConclusionsDiscussionResults
Same fidelity and gamut, but different gamut shape, can
lead to significantly different preference.
Dislike
Like
5.5
5.0
4.5
4.0
-
Goals Hypotheses Methods ConclusionsDiscussionResults
Same fidelity and gamut, but different gamut shape, can
lead to significantly different preference.
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y = 85.457x3 + 12.746x2 - 9.6207x + 4.1387R² = 0.8132
1
2
3
4
5
6
7
8
-30% -20% -10% 0% 10% 20% 30%
Me
an P
refe
ren
ce R
atin
g
Hue Bin 16 Chroma Shift (Rcs,h16)
Dislike
Like
Goals Hypotheses Methods ConclusionsDiscussionResults
Preference increased with red-saturation, with limits.
-
Goals Hypotheses Methods ConclusionsDiscussionResults
Best Model for Preference:
Like-Dislike = 7.396 - 0.0408(Rf) + 103.4(Rcs,h163) - 9.949(Rcs,h16)
R² = 0.93552
3
4
5
6
7
2 3 4 5 6 7
Par
tici
pan
t P
refe
ren
ce R
atin
g
TM-30 Model Predicted Preference Rating
More Liked
Less Liked
Post-hoc modeling of preference
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Goals Hypotheses Methods ConclusionsDiscussionResults
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
Rcs
,h1
6
Experimental Preferred Zone*
What about existing light sources?
-
Goals Hypotheses Methods ConclusionsDiscussionResults
60
70
80
90
100
110
120
130
140
50 60 70 80 90 100
IES
TM-3
0 R
g
IES TM-30 Rf
Phosphor LED
Color Mixed LED
Hybrid LED
Standard Halogen
Filtered Halogen
Triphosphor Fluorescent, 7XX
Triphosphor Fluorescent, 8XX
Triphosphor Fluorescent, 9XX
Metal Halide
Experimental
Preferred
Zone*
What about existing light sources?
-
Goals Hypotheses Methods ConclusionsDiscussionResults
• TM-30 measures demonstrated excellent correlation with participant evaluations
• Sources that increased saturation in red were liked(Chroma shift in “red” of about 2% to 16%)
• Today’s commercially available sources are unlikely to be optimized for preference
Conclusions from this small study