color measurement basics

8/2/2019 Color Measurement Basics

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Color Measurement in deep- You have 7 must know things -

Tomo IRINO @ R/V Kairei

September 18, 2007


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Specular component = direct reflection from sample surface

Cross section of sensor- Principle of spectrum measurement by CM-2002 -

Surface condition is not controllable in many case.

We prefer specular component excluded (SCE).


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Appropriate set of

white calibration board and memory card


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0

5

10

156065707580859095

100

400 450 500 550 600 650 700

White calibration boardPC-03 Sec16 15cmPC-03 Sec14 93cm

Reea

Wave Length (nm)

Spectrum of visible light

Zero calibration

White calibration


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Bias from Transparent Film

Iobserve Rw Tw2

1 Rw Rsample1 Rw 1 Rw Rsample

I0

Rsample

1

1 Rw

Robserve Rw

Rw Robserve Tw2 Rw2

Iobserve

Robserve

I0

True reflectance of sample surface is (for each wave length):


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30

40

50

60

70

80

400 450 500 550 600 650 700

(nm)

Effect of Transparent film

0

0.5

1

1.5

2

2.5

3

3.5

4

91

92

93

94

95

96

400 450 500 550 600 650 700

(nm)


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Data card

Data card can store 1000 of values

If you measure 1001st sample,1st value is lostand

all data are re-numbered.


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Value

BG R

YG

B P

RP

YR

GY

PB

Chroma

N

Munsell system

7.5Y 3/2

Hue

Value

Chroma

Olive black

Black and white:

N value/0

Hue

3-dimensinalQualitativeColor expression

System


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8

9

10

11

12

13

400 450 500 550 600 650 700

PC-03 Sec16 15cmsensitivity of eye sensor for redsensitivity of eye sensor for greensensitivity of eye sensor for blue

Reea

Wave Length (nm)

8

9

10

11

12

13

400 450 500 550 600 650 7000

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Reea

Wave Length (nm)

XY

Z

X K S()x()R()

Y K S()y()R()

Z K S()z ()R()

K 100

S()y()

L* 116y 16a* 500(x y)

b* 200(y z)

x

X

Xn

1

3

,X

Xn 0.008856

7.787X

Xn

16

116 ,X

Xn 0.008856

, y

Y

Yn

1

3

,Y

Yn 0.008856

7.787Y

Yn

16

116 ,Y

Yn 0.008856

, z

Z

Zn

1

3

,Z

Zn 0.008856

7.787Z

Zn

16

116 ,Z

Zn 0.008856

Light

To brain

How we feel color?

BrightnessRed (+) Green (-)

Yellow (+) Blue (-)


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L* L*-a*-b* system

b*

a*C*

H

C* : metric chromaH: metric hue

a*

b*

L*

3-dimensinalQuantitativeColor expression

System

L*-C*-Hsystem

C* a* 2 b* 2

H tan1b*

a*

, (0 H


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Light source: C (day-light from north-faced window)

or

D65 (day-light with 6500K)

View area (angle): 2 or 10

Specular component: excluded (SCE) or included (SCI)

Feeling of color is controlled by:

L*-a*-b* is calculatedfrom reflectance spectrum

on C, 2and SCE

In our cruise,


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Check Points

Specular Component (SCE) Serial number of white calibration board

and memory card

Zero / White Calibration (Dont forget!)

Transparent film you use

Dont go beyond 1000 samples!

Light Source (C? D65?)

View area (2? 10?)

Before Measurement:

During Measurement:

After Measurement:

color measurement basics

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