C o l o u ra p p e a r a n c eM i n g R o n n i e r L u o

Z h e j i a n g U n i v e r s i t y , H a n g z h o u , C h i n a

ICC DevCon 2020 Ming Ronnier Luo 2

Scope

• CIE Colorimetry

• Colour appearance models

• Recent developments

Scope

CIE Colorimetry

Colour appearance models

Recent developments

CIE 015:2018 Colorimetry 4th Edition

CIELUVCIELAB XYZ

CIEDE2000

Spectral r

CMF2o & 10o

SPDD65 & A

s10() m10() l10()

-60

-40

-20

0

20

40

60

80

100

120

-60 -40 -20 0 20 40 60 80 100 120

a*

b*

0.0

0.5

1.0

1.5

2.0

2.5

380 480 580 680 780

Wavelength ( nm )

Tri

sti

mu

lus v

alu

es

z ( )

y ( )

x ( )

a*

b*

C*ab

hab

L*

CIECAM02

CAM02-UCS

SPDCIE LEDs

New CIE LED illuminants

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

360nm 410nm 460nm 510nm 560nm 610nm 660nm 710nm 760nm

Targ

et

wavelength

LED-B1 LED-B2 LED-B3 LED-B4 LED-B5

0

0.1

0.2

0.3

0.4

0.5

0.6

360nm 410nm 460nm 510nm 560nm 610nm 660nm 710nm 760nm

Targ

et

wavelength

LED-BH1 LED-RGB1 LED-V1 LED-V2

CIE 015:2018 Colorimetry 4th Edition

Colour Appearance Model

X Y Z

Xw Yw Zw LA Yb

CIECAM02

(CIECAM16)

Surround:

Average,

Dim and

Dark

Lightness (J)

Redness-Greenness (a)

Yellowness-Blueness (b)

Chroma (C)

Colourfulness (M)

Saturation (s)

Hue angle (h)

Hue composition (H)Ref.

white

Light Sources

Colour appearance attributes

• Lightness

• Brightness

• Chroma

• Colourfulness

• Saturation• Hue angle

• Hue composition

1. M. R. Luo, et. al. Quantifying colour appearance: Part I CRA 16 (1991) 166-180.

2. M. R. Luo, et. al. Quantifying colour appearance: Part II CRA 16 (1991) 181-197.

3. M. R. Luo, et al., Quantifying colour appearance: Part III CRA 18 (1993) 98-113.

4. M. R. Luo, et al., Quantifying colour appearance: Part IV CRA 18 (1993) 191-209.

5. M. R. Luo, et al., Quantifying colour appearance: Part V CRA 20 (1995) 18-35.

Relationship between the absolute and relative colour appearance attributes

Lightness

Chroma

BrightnessLightness

BrightnessChroma

Brightness

essColourfuSaturation

Brightness

essColourfuChroma

Brightness

BrightnessLightness

white

white

white

white

=

==

=

=

ln

ln

Visual Phenomena

1. Chromatic adaptation effect

2. Hunt effect

3. Stevens effect

4. Surround effect

5. Lightness contrast effect

Chromatic Adaptation

Open end - SE

Open circle - A

Blue

RedGreen

Hunt Effect

0

20

40

60

80

100

120

140

160

180

-2 -1 0 1 2 3 4 5 6

log 10Lw

C*=0

C*=20

C*=40

C*=60

C*=80

Stevens Effect

0

100

200

300

400

500

600

700

800

-2 -1 0 1 2 3 4 5 6

log10Lw

L*=0.01

L*=20

L*=40

L*=60

L*=80

• CIECAM97s• CIE TC1-34 Testing colour appearance models• M. R. Luo and R. W. G. Hunt, The structures of the CIE 1997 colour appearance model (CIECAM97s),

Color Res. Appl., 23 138-146 (1998).

• CIECAM02• CIE TC8-01 Colour Appearance Modelling for Colour Management

Applications, Scottsdale, Arizona, USA (1998-2002)• N. Moroney, M. D. Fairchild, R.W.G. Hunt, C Li, M. R. Luo and T. Newman, The CIECAM02 Color

Appearance Model, CIC2002, Scottsdale, Arizona, pp23-27.

• CIECAM16• CIE JTC10 A new colour appearance model for colour

management systems: CIECAM16, （Jiju, South Korea 2017-2020).

• C. J. Li. Z. Li, Z. Wang, Y. Xu, M. R. Luo, G. H. Cui, M. Melgosa, M. H. Brill, and M. R. Pointer, Comprehensive color solutions, CAM16, CAT16 and CAM16-UCS, Col., Res. and Appl., (2017), pp42703-718.

CIE Colour Appearance Models

CIELAB CAM02-UCS

-60

-40

-20

0

20

40

60

80

100

120

-60 -40 -20 0 20 40 60 80 100 120

a*

b*

-60

-40

-20

0

20

40

60

80

100

-60 -40 -20 0 20 40 60 80 100

a

b

Uniform Colour Spaces

M. R. Luo, G. Cui, C. Li, Uniform Colour Spaces Based on CIECAM02 Colour Appearance Model, Color Res. Appl. 31 (2006) 320-330.

Scope

CIE Colorimetry

Colour appearance models

Recent developments

Lightness (J’)

Red-Green (a’)

Yellow-blue (b’)

Colourfulness (M’)

Hue angle (h)

DJ’, DM’, DH, DEJ’a’b’

CIECAMInput and output parameters

X Y Z

Xw Yw Zw LA Yb Surround: Average, Dim

and Dark

Redness

Greenness

Achromatic

signal

Yellowness

Blueness

Angle subtense

(q)

Related Red-Green (a)

Yellow-blue (b)Brightness (Q)

Lightness (J)

Colourfulness (M)

Chroma (C)

Saturation (s)

Hue angle (h)

Hue composition (H)

UnrelatedBrightness (Qun)

Colourfulness (Mun)

White amount (Wun)

Hue

Recent developments

Incomplete chromatic adaptation

CAT02- Incomplete adaptationZhai et al, OE 26(2018)7724-39

Zhu et al, CRA(DOI/10.1002/Col.22500)

D=F{1-(1/3.6)e[(-La-42)/92] }

D=a0+a1du’+a2dv’+a3sqrt(du’2+dv’2)

D= Function (Surround, La, [CCT, Duv] or [u’v’], Area, Time, media)

0

0.2

0.4

0.6

0.8

1

2500 5000 7500 10000

D

CCT/K

surface

self-luminous

projector

Present result

Y. Zhu, M. Wei, M. R. Luo, Effects of Adapting Chromaticities and Luminance on Color Appearance on Computer Displays Using Memory, Color Res. and Appl., 000-000

Simultaneous colour contrast

-1

-0.5

0

0.5

1

-180 -120 -60 0 60 120 180

∆H

∆h

modeling_7° modeling_15°

-10

-5

0

5

10

15

20

-100 -50 0 50 100

Result (ΔL*)

Background（ΔL*）

result

Y. Zhu and M. R. Luo, (O) Proposed Modification to the CAM16 Colour Appearance Model to Predict the Simultaneous Colour

Contrast Effect, 27th Color and Imaging Conference (2019), Paris, 2019, pp190-194.

Whiteness-DepthBlackness-Vividness

Whiteness

Blackness

Y. J. Cho, L. C. Ou and M. R. Luo, A cross-culture comparison of saturation, vividness, blackness and

whiteness scales, Color Res and Appl.,42(2017)203-215

-3

-2

-1

0

1

2

3

0 20 40 60 80 100

Bri

tis

h O

bs

erv

er

Res

po

ns

e

Vividness (Vab*)

r = -0.86

-3

-2

-1

0

1

2

3

0 20 40 60 80 100

Bri

tish

Ob

serv

er

Resp

on

se

Depth (Dab*)

r = -0.82

Whiteness

Saturation

Blackness

Meaningful colour appearance scalesWang and Luo, R&A, 10(2018)458-470

20

30

40

50

60

70

80

0 10 20 30 40

L*

C*ab

PR650

Caucasian

Oriental

South Asian

Whiteness – Depth

Blackness - Vividness

Back yard of CII (Derby)

Point 1~10 sky

Point 11~20 plants

Point 21~30 building

Jzazbz Model for HDR/WCG

M. Safdar, G. Cui, Y. J. kim and M. R. Luo, Perceptually uniform color space for image signals including high dynamic range and wide gamut, Optics Express, 25(2017), pp15131-15151.

-50 0 50 100

-50

0

50

100

CIELAB

a*

b*

-40 -20 0 20 40-40

-30

-20

-10

0

10

20

30

40

CAM16-UCS

aM

bM

-2 0 2 4-3

-2

-1

0

1

2

3

4

5

IPT

P

T

-0.1 -0.05 0 0.05 0.1 0.15-0.1

-0.05

0

0.05

0.1

0.15

Jza

zb

z

az

bz

COMBVF Ellipses

Hung & Berns Data

Hue Linearity - WCG

Unitary Hue Data Other Hue Data

UCS’s performance

-100 -50 50 100

a*

-100

-50

50

100

b*

Rescaled Chromatic discrimination ellipses in CIELAB

aM

-40

-30

-20

-10

10

20

30

40

bM

Rescaled Chromatic discrimination ellipses in CAM02-UCS

-0.3

-0.2

-0.1

0.1

0.2

0.3

CT

-0.3 -0.2 -0.1 0.1 0.2 0.3

CP

Rescaled Chromatic discrimination ellipses in ICTC

P

-0.15 -0.1 -0.05 0.05 0.1 0.15

az

-0.15

-0.1

-0.05

0.05

0.1

0.15

bz

Rescaled Chromatic discrimination ellipses in Jza

zb

z

Colour Spaces Local (%) Global (%)

CIELAB 222 48

CAM02-UCS 138 31

ICTCP 175 59

Jzazbz 160 67

𝑳𝒐𝒄𝒂𝒍 =

1𝑁σ𝑖=1𝑁 𝐴𝑖

𝐵𝑖− 1

2

1× 100% (8)

𝐺𝑙𝑜𝑏𝑎𝑙 =

1𝑁σ𝑖=1𝑁 𝑆𝑖 − ҧ𝑆

2

ҧ𝑆× 100% (9)

Lightness (J’)

Colourfulness (M’)

Hue angle (h)

DJ’, DM’, DH, DEJ’a’b’

CIECAMInput and output parameters

X Y Z

Xw Yw Zw LA Yb Surround: Average, Dim

and Dark

Redness

Greenness

Achromatic

signal

Yellowness

Blueness

Angle subtense

(q)

UCS

1D-scales

Related Brightness (Q)

Lightness (J)

Colourfulness (M)

Chroma (C)

Saturation (s)

Hue angle (h)

Hue composition (H)

Vividness (V)

Depth (D)

Saturation (s)

Blackness (K)

Whiteness (W)

Clarity (Cl)

2D-scales

Colou reproduction

• Spectral (R%)

• Relative Colorimetric (XYZ)

• Absolute Colorimetric (XL YL ZL)

• Appearance (JCh, QMh)

• Preference (JCh, QMh)

Go beyond colour!

Total Appearance

Gloss

Texture

Translucency

CIELUVCIELABXYZ

CAM02-UCS

Jzazbz

CAM16ZCAM

CIEDE2000

CAT16 (D) 2D colour appearance

Unrelated

colours

Colour contrast

HDR/WCG

Spectralreflectance

CMF2o & 10o

CIE 2015colorimetry

SPDD65 & A

Spatial colour differences

Conclusions

• Colour appearance models • viewing parameters, Correlates, Visual phenomena

• Recent developments• CAT-D

• Colour contrast

• 2D-colour appearance scales

• Jzazbz UCS

• HDR and WCG applications • Hue linearity 0

0.2

0.4

0.6

0.8

1

380 480 580 680

Thanks for your attention!

Cel.zju.edu.cn

m.r.luo@zju.edu.cn