Effect of Test Patch Location on Color Appearance, in the Context of 3D Objects Bei Xiao and David H.Brainard University of Pennsylvania.

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Presentation transcript:

Effect of Test Patch Location on Color Appearance, in the Context of 3D Objects Bei Xiao and David H.Brainard University of Pennsylvania

What Color is the Mug?

Most Appearance Studies Consider Flat Uniform Patches

Highlight Inter-reflection A Complex Pattern of Light is Reflected from 3D Objects

Surface Gloss Increases the Variation of Reflected Light

How do people perceive the color of different parts of an object? Questions How do material properties of the object affect color perception?

Task: Asymmetric Color Matching TestMatch

Task: Asymmetric Color Matching Adjusting! TestMatch

Task: Asymmetric Color Matching Adjusting! TestMatch

Task: Asymmetric Color Matching Adjusting! TestMatch

Task: Asymmetric Color Matching Adjusting! TestMatch

Task: Asymmetric Color Matching Adjusting! TestMatch

Task: Asymmetric Color Matching TestMatch Done!

Rendering Methods Images are rendered wavelength by wavelength using customized Matlab software (RenderToolbox). The underlying renderer is Radiance. RenderToolbox is available at

Ward Model of Surface Reflection Specular Component (material properties) Diffuse Component (body color)

Experimental Variables: Location, Material, Color Material Color Location

Results: Pictorial Representation Mean Up Match Up Mean Bottom Match Bottom Test Up Test Bottom

Results: Pictorial Representation Match Up Match Bottom Test Up Mean Up Test Bottom Mean Bottom

Results: Pictorial Representation Test Up Mean Up Match Up Test Bottom Mean Bottom Match Bottom

Results: Pictorial Representation Test Up Mean Up Match Up Test Bottom Mean Bottom

Match Bottom Results: Pictorial Representation Test Up Mean Up Match Up Test Bottom Mean Bottom

Match Bottom Results: Pictorial Representation Test Up Mean Up Match Up Test Bottom Mean Bottom

Preliminary Conclusions Changing test patch location of an object has a small effect on color perception of the patch. This is not predicted by the average of the light reflected from the patch. Effect of surface material properties on color perception of the patch is also small.

Quantitative Data Representation test mean Xiao, B. and Brainard, D.H. (under review) Visual Neuroscience

Transformed Data Representation test mean

Transformed Data Representation test mean match

Transformed Data Representation test mean match

Transformed Data Representation test mean match

Transformed Data Representation test mean match

Transformed Data Representation test mean match

Soccer Ball Experiment, More Data

Location Effect Index (LEI) up bottom Vt Vm For each material condition: LEI = [ |Vm| / |Vt| ] test mean match

LEI Histograms Corrected mean: Purple = 0.09 Yellow-green = 0.13

Material Influence Index (MII) For each mach: MII = [ |Vm| / |Vt| ] matte glossy test mean match Vt Vm

MII Histograms Corrected mean: Purple = 0.17 Yellow-green = 0.13

Conclusions Effect of location is small in comparison with the mean prediction. This suggests color appearance is stable across different parts of an object. Matches are not predicted by the average of the light reflected across the image of the object. Were interested in the color appearance of 3D objects in rich scenes. Surface gloss has a small effect on color perception of the test patch on 3D objects when the diffuse component is constant.

Prof. David H. Brainard Ah Rim Shin Lu Yin Dan Lichtman Dr. Sarah Allred Prof. James Hillis Dr. Robyn Oliver Chris Broussard Acknowledgement

Implications For Models Image-statistics: Use image mean, skewness, percentiles to estimate diffuse reflectance (body color). Inverse-optics: estimating geometry of the light source and use the estimated geometry to infer diffuse reflectance.

Design: Test Patch Location Effect

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

CIELAB Representation of Test Stimuli

LEI Histograms, Compared with Residuals

Material Influence Index (LEI)

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom

Results: Pictorial Representation Test Up Match Up Mean Up Test Bottom Match Bottom Mean Bottom