SURFACE COLOR AND SHADOWS

TESTING THE D’ZMURA-IVERSON MODEL

Laurence T. Maloney Joong Nam Yang

Psychology and Neural Science Visual Sciences Center New York University University of Chicago

ARVO 2000 May 3, 2000 Ft. Lauderdale, Florida

1. Cues to the Illuminant

[I]n our observations with the sense ofvision, we always start out by forming a judgment about the colours of bodies, eliminating the differences of illumination by which a body is revealed to us.

von Helmholtz

Surface Color Perception

Illuminant Chromaticity

dRE

dRE

dRE

E

E

E

33

22

11

Photoreceptor Array

Illuminant

Surfaces

xyS

E

3,2,1, kR xyk

Surface Color Algorithms

xyxy

Maloney (1999)

Cues to the Illuminant

Reference Surfaces Brill (1978) Buchsbaum (1980)

Subspace Constraints Maloney & Wandell (1986) D’Zmura & Iverson (1993)

Chromatic Aberration Funt & Ho (1990)

and more …….

Specularity Lee (1986) D’Zmura & Lennie (1986)

Mutual Illumination Drew & Funt (1990)

Shadow Edge Cue D’Zmura & Iverson (1994)

Maloney (1999)

UNIFORM BACKGROUND CUE

SPECULAR HIGHLIGHT CUE

D’ZMURA-LENNIE-LEE CUE

MatteContaminationProblem

Spec

ular

Mat

te 1

Matte 2

SHADOW EDGE CUE

D’Zmura (1992)

Illuminant Cue Combination

UniformBackground

SpecularHighlight

DZ-D-LSpecularity

Dynamic Re-Weighting

SceneIlluminantEstimate

Cue Promotion

Shadow

Maloney (1999)

2. Perturbation Methods

Perturbation Methods

base D65 perturbed target A

Specular information perturbed …..

Yang, Maloney & Landy, ARVO, 1999

JNYTarget A

Perturbed Illuminant D65 (matte) Illuminant A (specular)

Base D65

v’

u’

?

JNYTarget A

Perturbed Illuminant D65 (matte) Illuminant A (specular)

Base D65

v’

u’

?

JNYTarget A

Perturbed Illuminant D65 (matte) Illuminant A (specular)

Base D65

v’

u’

?

v’

u’

0.16 0.20 0.24 0.16 0.20 0.24

0.52

0.45

0.52

0.45

CHF GT

EC BRM

Yang, Maloney & Landy, ARVO, 1999

CHF

V’

u’

Average Scene Chromaticity

Yang, Maloney & Landy, ARVO, 1999

3. Methods

400 700

1

0

N = 12

Multi-Channel Rendering

RADIANCE

Larson (1992)

Stimulus Stereo Pairs

D65

A

RADIANCE

SHADOW EDGE CUE

D65

SHADOW EDGE CUE

A

SHADOW EDGE CUE

Perturbed

Perturbation Methods

base D65 perturbed target A

Specular information perturbed …..

Achromatic Matching

4. Results

GT

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 AGT

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 A

JLS

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 AJLS

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 A

JNY

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 AJNY

0.16 0.20 0.24

u’

v’

0.52

0.45

D65 A

There are several candidate illuminant cues.

A specularity cue influences human color vision (Yang, Maloney & Landy, 1999).

The shadow edge cue does not influence human color vision, for our choice of scene.

SUMMARY

Supported by NIH/NEI EY08266

D65 A

A D65

Photoreceptor Excitations

dRSE

dRSE

dRSE

xyxy

xyxy

xyxy

33

22

11