Basic of Colorimetry

BASIC PRINCIPLESBASIC PRINCIPLESOF COLORIMETRYOF COLORIMETRY

EyeLight

Object

Color Vision and Perception

LIGHTLIGHT

Electromagnetic Radiation

Gamma

X-Ray

UV

Infrared

Short waves

Ultrashort waves

Light1pm 1nm 1mm 1m 100m1A

The Colors of Light

Energy

Wavelenght of Photons

White Light

Farbraum

White White LightLight PrismPrism

Generation of the Spectrum

Spectral Analysis of the Light

UVUV I RI R

400nm 550nm 700nm

Light Sources

Primary Light Source

Secondary Light Source

Average Daylight (5500 K)

Tungsten Halogen Lamp (3200 K)

Color Composition of Light Sources Color Temperature

Relative Spectral Distribution of Standard Illuminants

300 nm 400 nm 500 nm 600 nm 700 nm0

50

100

150

200

250

300

Wavelenght in nm

Rel. Intensity

A

D 65

C

Color Color MixtureMixture

Green

RedBlue

Additive Color Mixture

Subtractive Color Mixture

Cyan Magenta

Yellow

Matching of Pigments and Colors -Example: Subtractive Color Mixing

Yellow (Y)Yellow (Y)

Purple (M)Purple (M) Blue-Green (C)Blue-Green (C)

Color Circle

OBJECTOBJECT

Effect of light and materiel Example of Printing Inks

Light Source

Illustration of Spectral Remission

Wavelength in nm

400 nm 550 nm 700 nm0%

50%

100%

CYAN

The EyeThe Eye

Eye in Cross-Section

Optic Nerve

Yellow Spot

Pigmentepithel

Retina

Vitreous Humour

Cornea

Pupil

Iris

LensBlind Spot

Retina

LightLight

ConesCones

RodsRods

400 500 600 7000

0,5

1

1,5

2

2,5 x

y

z

Wavelength in nm

CIE Color- Matching Functions

2°- and 10°- Standard Observer

2°2°

10°10°

Colorimetry

How to obtain X Y Z - Values

x

x x x

=

I I I

R S

R X S

x y

X Y

z

Z

R: Remission SpectrumR: Remission Spectrum

S: Spectral DistributionS: Spectral Distribution

of Lightof Light

Spectral Tristimulus CurvesSpectral Tristimulus Curves

Primaries X,Y,ZPrimaries X,Y,Z

Description of Colors

Color

HueChromaBrightness

"Green"

"Blue"

"Brilliant"

"Grayish"

"Bright"

"Dark"

CIE Cromaticity Diagram

0 0,2 0,4 0,6 0,8

0

0,2

0,4

0,6

0,8

E

Purple Boundary

Spectrum Locus

xx

y

CIE Color Space

100

60

20

0

0

y

x

E

Y

40

80

MacAdam - Ellipses

x

0

0,2

0

0,2

0,4

0,6

0,8

y

520

510

500

490

480

470460450

530540

550

560

570580

590600

610620

630640

0,4 0,6 0,80

Transformation

*

a*

b*

CIELAB Color Space

Green

Red

Yellow

Blue

Withe

Black

h

L*

-

-

b*+

a*+

C*

L: Brightnessa: Green - Red - Axis b: Yellow - Blue- Axish°: Hue-AngleC: Chroma

APPLICATIONAPPLICATION

Color Deviation

H*

0,4 0,6 0,8 1 1,2 1,4 1,60,4

0,6

0,8

1

1,2

1,4

1,6

a*

b*

a*

b*

Reference

SampleSample

Reference

C*b*

a*

+Yellow

+Red

+Blue

+Green

Clearer+Yellow

+RedDuller

L*, C*, H* L*, C*, H*

Reference Sample

L*, a*, b* L*, a*, b*

Reference Samples

L* a* b*

L* C* H*

Total Color Deviation

--

E

=

E

=

Differences

How to Interprete Color Differences

E* 0.0 to 0.2 not visible E* 0.2 to 1.0 very small E* 1.0 to 3.0 smallE* 3.0 to 6.0 mediumE* 6.0 and + large

Colorimetric Systems

Primaries

X Y Z

CIE Cromaticity Diagram:x,y Chromaticity CoordinatesY Brightness

CIE-UCS Cromaticity Diagram:u´,v´Y Brightness

CIELUV Color Space:u*,v*L* Brightness

CIELAB Color Space:a*,b*L* Brightness

DIN Color System:T:S:D

Munsell, Hue,Chroma, ValuePantoneHKSRAL

Others:

Metameric Colors

400 nm 550 nm 700 nm0%

50%

100%

Wavelengths

Fluorescence

400 nm 550 nm 700 nm0%

50%

100%

Wavelengths