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

Surface Color Perception [I]n 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

Illuminant Chromaticity

Illuminant Surfaces Photoreceptor Array

Surface Color Algorithms Maloney (1999)

Cues to the Illuminant Reference Surfaces Subspace Constraints 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 Matte Contamination Problem Specular Matte 1 Matte 2

SHADOW EDGE CUE D’Zmura (1992)

Illuminant Cue Combination Cue Promotion Uniform Background Specular Highlight Illuminant Estimate Scene DZ-D-L Specularity Shadow Dynamic Re-Weighting Maloney (1999)

2. Perturbation Methods

Perturbation Methods target A base D65 perturbed Specular information perturbed ….. Yang, Maloney & Landy, ARVO, 1999

? v’ u’ JNY Target A Base D65 Perturbed Illuminant D65 (matte) Illuminant A (specular) u’

? v’ u’ JNY Target A Base D65 Perturbed Illuminant D65 (matte) Illuminant A (specular) u’

? v’ u’ JNY Target A Base D65 Perturbed Illuminant D65 (matte) Illuminant A (specular) u’

v’ u’ CHF GT EC BRM Yang, Maloney & Landy, ARVO, 1999 0.52 0.45 0.52 0.16 0.20 0.24 0.16 0.20 0.24 u’ Yang, Maloney & Landy, ARVO, 1999

Average Scene Chromaticity CHF V’ u’ Yang, Maloney & Landy, ARVO, 1999

3. Methods

Multi-Channel Rendering 1 N = 12 RADIANCE Larson (1992) 400 l 700

Stimulus Stereo Pairs D65 A RADIANCE

SHADOW EDGE CUE D65

SHADOW EDGE CUE A

SHADOW EDGE CUE Perturbed

Perturbation Methods target A base D65 perturbed Specular information perturbed …..

Achromatic Matching

4. Results

D65 A D65 A GT GT v’ 0.52 0.45 v’ 0.52 0.45 0.16 0.20 0.24 0.16 0.20 0.24 u’ u’

D65 A D65 A JLS JLS v’ 0.52 0.45 v’ 0.52 0.45 0.16 0.20 0.24 0.16 0.20 0.24 u’ u’

D65 A D65 A JNY JNY v’ 0.52 0.45 v’ 0.52 0.45 0.16 0.20 0.24 0.16 0.20 0.24 u’ u’

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

D65 A A D65

Photoreceptor Excitations