Sources, Surfaces, Eyes - resodance.comresodance.com/ali/IESAnnCon03.pdf · Samp0 Samp1 Samp2 Samp3 Samp4 Samp5 wrt D65 x 0.31 0.13 0.21 0.37 0.53 0.68 y 0.33 0.15 0.77 0.63 0.47

Sources, Surfaces, Eyes

An investigation into the interaction oflight sources, surfaces, eyes

IESNA Annual Conference, 2003

Jefferey F. KnoxDavid M. Keith, FIES

Sources, Surfaces, & Eyes - Research

* Research– Scientific activity dedicated to discovering

what makes grass green.• Russell Baker

Sources, Surfaces, and Eyes Overview

* Why is the spectral nature of light important?– Human color perception

* Why is a new calculation technique necessary?– The Lumen is spectrally ignorant

* What are the ramifications of a new calculation procedure?– more colorful predictions of our world

* For Instance…..

Spectral Information is Important




* Both Brightness and Color are needed to complete the human visual process

* In order to understand how including spectral information effects lighting, we need to understand the basics of radiation and light

Lighting Basics: The Lumen

Photopic Spectral Luminous Efficiency Function

0

0.2

0.4

0.6

0.8

1

1.2

360

394

428

462

496

530

564

598

632

666

700

734

768

802

WavelengthSe

nsiti

vity

Series1

Spectral Power Distribution 150 HPS

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+001.20E+00

1.40E+00

380

411

442

473

504

535

566

597

628

659

690

721

752

Wavelength (nm)

Pow

er (W

atts

)

Series1

Lumenssource = K * ∑ [ S(λ) * v(λ) ]Sum λ from 360 to 770 nanometers

Lumens = K * ∑ [ P(λ) * v(λ) ]

Lighting Basics: Reflectance

* Luminous reflectance:– Any of the geometric aspects of reflectance in

which both the incident and the reflected flux are weighted by the spectral luminous efficiency of radiant flux V(λ).

– Note: Unless otherwise qualified, the term “reflectance” means luminous reflectance.

– “GLOSSARY OF LIGHTING TERMINOLOGY” IESNA Lighting Handbook

Lighting Basics: Reflectance

* Reflectance = Lumensoff ÷ Lumenson

* Average Reflectance– What is average reflectance?– Is it related to a specific source?

Lighting Basics: Contrast

Cmod = (Lmax - Lmin ) / (Lmax + Lmin)

For a perfectly diffuse reflector Luminance = Exitance ÷ πExitance = Lumenson * Reflectance

Cmod = (p max - p min ) / (p max + p min)

Basic Problems: The Lumen

* The Lumen is Spectrally Ignorant– It contains no information about its spectral

composition.


* A Lumen is a Lumen is a Lumen


* A Lumen is a Lumen is a Lumen– Every lumen from a source is the same as every

other lumen from that source!


* A Lumen is a Lumen is a Lumen– Every lumen from a sources is the same as every

other lumen from that source!– BUT!– Every lumen from one source is not the same as

every lumen from a different source.

Basic Problems: Reflectance


* Because reflectance is lumen-based, it too is Spectrally Ignorant

* Every interaction of light with a surface changes the spectral distribution of every lumen reflected

Basic Problems: Reflectance


* Because reflectance is lumen-based, it too is Spectrally Ignorant

* Every interaction of light with a surface changes the spectral distribution of every lumen reflected

* WHAT WE SEE IS REFLECTED LIGHT!

Basic Problems: Contrast

Can You See This?

Basic Problems: Contrast

Obviously we need to find some way to make better predictions that include color and color difference . . .

Why a New Calc. Technique

* Our world is not all shades of gray

Why a New Calc. Technique

* Our world is not all shades of gray* The effects of Color Difference need to be

evaluated and taken into consideration

New Calculation Basics

* Treat light as radiation – not as some compressed unit that follows energy theory

* Do not convert the radiation into lumens until it strikes the retina – and only if value information is all that is important

The New Basics - Reflectance

* Lumens onLumens on = K*∑[S(λ)*v(λ)]

* Lumens offLumens offclassic = ρaverage * {K*∑[S(λ)*v(λ)]}

Lumens offrevised = K * ∑ [ S(λ) * v(λ) * ρ (λ) ]

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

380 410 440 470 500 530 560 590 620 650 680 710 740 770

Ref

lect

ivity

0

50

100

150

200

250

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Spec

tral

Pow

er

Spectral Power Distribution Illum A

FHWA Blue Paint Spectral ReflectanceX

0

50

100

150

200

250

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Spec

tral

Pow

er

Product of Illum A & Blue Spectral Reflectance

=

0

50

100

150

200

250

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Spec

tral

Pow

er

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Rel

ativ

e M

agni

tude

Photopic Spectral Luminous Efficiency Function

Product of Illum A & Blue Spectral Reflectance

X

0

50

100

150

200

250

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Spec

tral

Pow

er=

Stimulus Produced by Illum A & Blue

683 * ∑ Stimulus = Lumens off

Spectral Reflectance Calculation

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

380 410 440 470 500 530 560 590 620 650 680 710 740 770

wavelength (nm)

Rel

ativ

e M

agni

tude

Source

Surface

Off Surface

vlambda

Stimulus

Sample Surface 5

00.20.40.60.8

11.2

380

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

Sample Surface 4

00.20.40.60.8

11.2

380

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

Sample Surface 3

00.20.40.60.8

11.2

380

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

Sample Surface 2

00.20.40.60.8

11.2

380

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

Sample Surface 1

00.20.40.60.8

11.2

380

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

Sample Surface 0

0

0.05

0.1

0.15

0.2

0.2538

0

409

438

467

496

525

554

583

612

641

670

699

728

757

Wavelength

Ref

lect

ivity

Series1

What does all this mean?Reflectance of sample surfaces under different sources

Samp0 Samp1 Samp2 Samp3 Samp4 Samp5

wrt D65

x 0.31 0.13 0.21 0.37 0.53 0.68

y 0.33 0.15 0.77 0.63 0.47 0.32

EqEnergy 20% 20% 20% 20% 20% 20%

D65 20% 22% 21% 20% 19% 18%

Illum A 20% 12% 17% 20% 23% 28%

HPS 20% 3% 2% 21% 45% 27%

M25H 20% 14% 19% 19% 34% 13%

M25U 20% 11% 21% 17% 40% 10%

M40H 20% 15% 19% 20% 32% 13%

M40U 20% 12% 19% 17% 38% 13%



wrt D65

x 0.31 0.13 0.21 0.37 0.53 0.68

y 0.33 0.15 0.77 0.63 0.47 0.32

EqEnergy 20% 20% 20% 20% 20% 20%

D65 20% 22% 21% 20% 19% 18%

Illum A 20% 12% 17% 20% 23% 28%

HPS 20% 3% 2% 21% 45% 27%

M25H 20% 14% 19% 19% 34% 13%

M25U 20% 11% 21% 17% 40% 10%

M40H 20% 15% 19% 20% 32% 13%

M40U 20% 12% 19% 17% 38% 13%

What does all this mean?Reflectance of sample colors under different sources


wrt D65

x 0.31 0.13 0.21 0.37 0.53 0.68

y 0.33 0.15 0.77 0.63 0.47 0.32

EqEnergy 20% 20% 20% 20% 20% 20%

D65 20% 22% 21% 20% 19% 18%

Illum A 20% 12% 17% 20% 23% 28%

HPS 20% 3% 2% 21% 45% 27%

M25H 20% 14% 19% 19% 34% 13%

M25U 20% 11% 21% 17% 40% 10%

M40H 20% 15% 19% 20% 32% 13%

M40U 20% 12% 19% 17% 38% 13%



wrt D65

x 0.31 0.13 0.21 0.37 0.53 0.68

y 0.33 0.15 0.77 0.63 0.47 0.32

EqEnergy 20% 20% 20% 20% 20% 20%

D65 20% 22% 21% 20% 19% 18%

Illum A 20% 12% 17% 20% 23% 28%

HPS 20% 3% 2% 21% 45% 27%

M25H 20% 14% 19% 19% 34% 13%

M25U 20% 11% 21% 17% 40% 10%

M40H 20% 15% 19% 20% 32% 13%

M40U 20% 12% 19% 17% 38% 13%

Sample Color ReflectancesSample Surfaces' Reflectances

0%5%

10%15%20%25%30%35%40%45%50%


EqEnergyD65Illum AHPSM25HM25UM40HM40U

Sign ColorsOrange 0.553 0.383 0.064 33.0%

Daytime33% 10564.75 5033.85 3481.15 584.59 X Y

0.562 0.35Refl D65*vl rho*X*S rho*Y*S rho*Z*S Wave S*rho 0.645 0.355

0.57 0.4290.100 1.95E-03 0.01 0.00 0.03 380 5.0 0.506 0.4040.100 3.35E-03 0.01 0.00 0.05 385 5.2 0.553 0.3830.100 6.56E-03 0.02 0.00 0.11 390 5.50.100 1.49E-02 0.05 0.00 0.25 395 6.90.100 3.28E-02 0.12 0.00 0.56 400 8.30.100 5.58E-02 0.20 0.01 0.96 405 8.70.050 1.11E-01 0.20 0.01 0.95 410 4.60.050 2.02E-01 0.36 0.01 1.72 415 4.60.050 3.74E-01 0.63 0.02 3.02 420 4.70.050 6.57E-01 0.97 0.03 4.68 425 4.50.050 1.01E+00 1.23 0.05 6.01 430 4.30.050 1.61E+00 1.57 0.08 7.77 435 4.80.050 2.41E+00 1.83 0.12 9.16 440 5.20.050 3.30E+00 1.93 0.17 9.88 445 5.50.050 4.45E+00 1.97 0.22 10.37 450 5.90.050 5.64E+00 1.87 0.28 10.24 455 5.90.050 7.07E+00 1.71 0.35 9.83 460 5.90.050 8.59E+00 1.46 0.43 8.89 465 5.80.050 1.04E+01 1.12 0.52 7.37 470 5.70.050 1.30E+01 0.82 0.65 6.01 475 5.80.050 1.61E+01 0.55 0.81 4.71 480 5.80.050 1.90E+01 0.33 0.95 3.46 485 5.6

0

10

20

30

40

50

60

70

80

380 420 460 500 540 580 620 660 700 740 780

0.3

0.32

0.34

0.36

0.38

0.4

0.42

0.44

0.2 0.3 0.4 0.5 0.6 0.7

Color Reproduction

Sign Colors

New Reflectance DataReflectances of FHWA Sign and Pavement Paints Under

Different Sources of IlluminationBlack Blue Green Yellow Orange Red White PMWhite PMYellow

x 0.31 0.14 0.13 0.49 0.55 0.61 0.31 0.31 0.44y 0.33 0.14 0.49 0.48 0.38 0.31 0.33 0.33 0.43

EqEn 2% 19% 31% 75% 35% 16% 90% 75% 68%D65 2% 21% 33% 73% 33% 14% 90% 75% 66%Illum A 2% 12% 23% 83% 44% 22% 90% 75% 74%HPS 2% 4% 6% 95% 58% 20% 90% 74% 87%M25H 2% 13% 24% 82% 39% 14% 90% 75% 74%M25U 2% 11% 22% 84% 39% 13% 90% 76% 76%M40H 2% 15% 26% 80% 38% 13% 90% 75% 73%M40U 2% 12% 22% 84% 41% 14% 90% 76% 76%



x 0.31 0.14 0.13 0.49 0.55 0.61 0.31 0.31 0.44y 0.33 0.14 0.49 0.48 0.38 0.31 0.33 0.33 0.43




x 0.31 0.14 0.13 0.49 0.55 0.61 0.31 0.31 0.44y 0.33 0.14 0.49 0.48 0.38 0.31 0.33 0.33 0.43


New Reflectance DataReflectances of Asphalt and Concrete Under Seven

Different Sources of Illumination

As1 As2 As3 Co1 Co2 Co3 Co4 Co5x 0.35 0.34 0.32 0.33 0.33 0.35 0.35 0.35y 0.36 0.36 0.34 0.35 0.35 0.35 0.36 0.36

EqEn 7.4% 7.3% 7.6% 33.3% 33.3% 26.0% 18.2% 25.9%D65 7.3% 7.3% 7.6% 33.2% 33.2% 25.7% 18.1% 25.7%Illum A 7.6% 7.5% 7.6% 33.7% 33.6% 26.8% 18.8% 26.6%HPS 7.7% 7.6% 7.7% 34.1% 34.0% 28.0% 19.4% 27.7%M25H 7.4% 7.4% 7.6% 33.5% 33.5% 26.4% 18.5% 26.3%M25U 7.5% 7.4% 7.6% 33.6% 33.6% 26.5% 18.6% 26.5%M40H 7.4% 7.3% 7.6% 33.5% 33.4% 26.3% 18.4% 26.2%M40U 7.5% 7.4% 7.6% 33.6% 33.6% 26.6% 18.6% 26.5%

New Basics - Contrast

* Same standard equation

Cmod = (p max - p min ) / (p max + p min)

– Still calculated in lumens

* Different method for calculating reflectance

New Basics – Color Difference

* Threshold– The difference in chromaticity or luminance

between two colors that makes them just perceptibly different. The difference may be in hue, saturation, brightness(lightness for surface colors) or a combination of the three.

New Basics – CIE L*a*b*

* First, the illuminant in the local context can be specified, also in terms of the R, G and B cone outputs, as a reference white. That is, the model

treats all colors as a combination of surface color and illuminant color, which allows the model to

be applied across a wider range of viewing conditions.


* Second, the trichromatic XYZ "primaries" are transformed mathematically to represent the Y/B

and R/G opponent dimensions (along with a lightness or white/black dimension), which allows

the models to reproduce the basic structure of color experience.


* Finally, CIELAB is based on a set of imaginary “primary” lights that have been chosen

specifically to make the color space perceptually uniform (at least, to the degree possible in a three

dimensional model). That is, a difference of 10 units on the lightness dimension has the same

perceptual impact as a 10 unit difference on the Y/B or R/G dimensions -- either separately or in

combination.


* delLAB is the Euclidean distance between two color loci

* ΔLAB = {(ΔL)2 + (Δa)2 + (Δb)2}1/2

Sign Colors – Contrast & delLAB

White on Red Black on White Black on Orange Black on Yellow White on GreenContrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB

EqEnergy 0.70 95 0.96 81 0.89 98 0.95 135 0.49 126

CIE D65 0.72 96 0.96 81 0.89 96 0.95 133 0.46 125

CIE A 0.60 101 0.96 81 0.91 108 0.95 138 0.59 121

HPS 0.63 76 0.96 81 0.93 112 0.96 148 0.87 100

M25H 0.74 82 0.96 81 0.90 99 0.95 138 0.58 114

M25U 0.75 77 0.96 81 0.90 97 0.95 141 0.61 107

M40H 0.74 84 0.96 81 0.90 98 0.95 137 0.56 116

M40U 0.73 79 0.96 81 0.91 99 0.95 140 0.61 110

Sign Colors – Contrast & delLAB

White on Red Black on White Black on Orange Black on Yellow White on GreenContrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB

EqEnergy 0.70 95 0.96 81 0.89 98 0.95 135 0.49 126

CIE D65 0.72 96 0.96 81 0.89 96 0.95 133 0.46 125

CIE A 0.60 101 0.96 81 0.91 108 0.95 138 0.59 121

HPS 0.63 76 0.96 81 0.93 112 0.96 148 0.87 100

M25H 0.74 82 0.96 81 0.90 99 0.95 138 0.58 114

M25U 0.75 77 0.96 81 0.90 97 0.95 141 0.61 107

M40H 0.74 84 0.96 81 0.90 98 0.95 137 0.56 116

M40U 0.73 79 0.96 81 0.91 99 0.95 140 0.61 110

Sign Colors – Red & White

Sign Colors – Black & Orange

Sign Colors – Black & Yellow

Asphalt & Paint – Contrasts and del L*a*b*PmWhite on As1 PmWhite on As2 PmWhite on As3Contrast delLAB Contrast delLAB Contrast delLAB

CIE D65 0.82 58 0.82 58 0.82 57CIE A 0.82 58 0.82 57 0.81 56EqEnergy 0.82 58 0.82 58 0.82 57HPS 0.81 57 0.81 57 0.81 56M25H 0.82 58 0.82 58 0.82 56M25U 0.82 58 0.82 58 0.82 56M40H 0.82 58 0.82 58 0.82 56M40U 0.82 58 0.82 58 0.82 57

PmYellow on As1 PmYellow on As2 PmYellow on As3Contrast delLAB Contrast delLAB Contrast delLAB

CIE D65 0.80 75 0.80 76 0.79 79CIE A 0.81 81 0.82 82 0.81 86EqEnergy 0.80 76 0.81 77 0.80 81HPS 0.84 90 0.84 91 0.84 96M25H 0.82 81 0.82 82 0.81 87M25U 0.82 82 0.82 83 0.82 88M40H 0.82 80 0.82 82 0.81 86M40U 0.82 82 0.82 84 0.82 88

Concrete & Paint – Contrasts & del L*a*b*PmWhite on Co1 PmWhite on Co2 PmWhite on Co3 PmWhite on Co4 PmWhite on Co5

Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLABCIE D65 0.39 26 0.39 26 0.49 34 0.61 42 0.49 35CIE A 0.38 26 0.38 26 0.47 30 0.60 36 0.47 30EqEn 0.39 26 0.39 26 0.49 30 0.61 36 0.49 30HPS 0.37 25 0.37 25 0.45 28 0.59 35 0.46 29M25H 0.38 27 0.39 27 0.48 30 0.61 36 0.48 30M25U 0.38 26 0.38 26 0.48 30 0.61 36 0.48 30M40H 0.39 27 0.39 27 0.48 30 0.61 36 0.48 30M40U 0.38 26 0.38 26 0.48 30 0.60 36 0.48 30

PmYellow on Co1 PmYellow on Co2 PmYellow on Co3 PmYellow on Co4 PmYellow on Co5

Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLAB Contrast delLABCIE D65 0.33 59 0.33 59 0.44 58 0.57 62 0.44 57CIE A 0.38 66 0.38 67 0.47 64 0.60 68 0.47 62EqEn 0.34 60 0.34 61 0.45 59 0.58 63 0.45 58HPS 0.44 75 0.44 75 0.51 72 0.63 77 0.52 70M25H 0.38 65 0.38 65 0.47 63 0.60 68 0.48 63M25U 0.39 66 0.39 66 0.48 65 0.61 69 0.48 63M40H 0.37 64 0.37 64 0.47 63 0.60 67 0.47 62M40U 0.39 66 0.39 66 0.48 65 0.61 69 0.48 64

Summary

* Keep the spectral information in the calc.* Spectral effects of illuminants cannot be

evaluated without considering the spectral reflectance of the lighted surfaces

* All this is evaluated as single bounce applications (no inter-reflections!)

* The significance of spectral effects can be greater when inter-reflections occur

Sources, Surfaces, Eyes

An investigation into the interaction oflight sources, surfaces, eyes.

IESNA Annual Conference, 2003

Jefferey F. KnoxDavid M. Keith, FIES

Documents

Sources, Surfaces, Eyes - resodance.comresodance.com/ali/IESAnnCon03.pdf · Samp0 Samp1 Samp2 Samp3 Samp4 Samp5 wrt D65 x 0.31 0.13 0.21 0.37 0.53 0.68 y 0.33 0.15 0.77 0.63 0.47