SURFACE COLOR AND SHADOWS

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SURFACE COLOR AND SHADOWS TESTING THE
DZMURA-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
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1. Cues to the Illuminant
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Surface Color Perception
In our observations with the sense of vision,
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
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Illuminant Chromaticity
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Illuminant
Surfaces
Photoreceptor Array
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Surface Color Algorithms
Maloney (1999)
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Cues to the Illuminant
Reference Surfaces Brill
(1978) Buchsbaum (1980) Subspace
Constraints Maloney Wandell (1986)
DZmura Iverson (1993) Chromatic Aberration
Funt Ho (1990)
and more .
Specularity Lee (1986)
DZmura Lennie (1986) Mutual
Illumination Drew Funt (1990) Shadow
Edge Cue DZmura Iverson (1994)
Maloney (1999)
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UNIFORM BACKGROUND CUE
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SPECULAR HIGHLIGHT CUE
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DZMURA-LENNIE-LEE CUE
Matte Contamination Problem
Specular
Matte 1
Matte 2
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SHADOW EDGE CUE
DZmura (1992)
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Illuminant Cue Combination
Cue Promotion
Illuminant Estimate
Scene
Shadow
Dynamic Re-Weighting
Maloney (1999)
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2. Perturbation Methods
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Perturbation Methods
Specular information perturbed ..
Yang, Maloney Landy, ARVO, 1999
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JNY
?
Target A
Base D65
v
Perturbed Illuminant D65 (matte) Illuminant
A (specular)
u
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JNY
?
Target A
Base D65
v
Perturbed Illuminant D65 (matte) Illuminant
A (specular)
u
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JNY
?
Target A
Base D65
v
Perturbed Illuminant D65 (matte) Illuminant
A (specular)
u
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0.52 0.45
CHF
GT
v
0.52 0.45
EC
BRM
0.16 0.20 0.24
0.16 0.20 0.24
u
Yang, Maloney Landy, ARVO, 1999
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Average Scene Chromaticity
CHF
V
u
Yang, Maloney Landy, ARVO, 1999
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3. Methods
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Multi-Channel Rendering
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N 12
RADIANCE Larson (1992)
0
400 l 700
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Stimulus Stereo Pairs
D65
A
RADIANCE
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SHADOW EDGE CUE
D65
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SHADOW EDGE CUE
A
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SHADOW EDGE CUE
Perturbed
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Perturbation Methods
target A
base D65 perturbed
Specular information perturbed ..
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Achromatic Matching
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4. Results
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D65 A
D65 A
GT
GT
0.16 0.20 0.24
0.16 0.20 0.24
u
u
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D65 A
D65 A
JLS
JLS
0.16 0.20 0.24
0.16 0.20 0.24
u
u
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D65 A
D65 A
JNY
JNY
0.16 0.20 0.24
0.16 0.20 0.24
u
u
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SUMMARY
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.
Supported by NIH/NEI EY08266
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D65 A
A D65
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Photoreceptor Excitations