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

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

2 What Color is the Mug?

3 Most Appearance Studies Consider Flat Uniform Patches

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

5 Surface Gloss Increases the Variation of Reflected Light

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

7 Task: Asymmetric Color Matching TestMatch

8 Task: Asymmetric Color Matching Adjusting! TestMatch

9 Task: Asymmetric Color Matching Adjusting! TestMatch

10 Task: Asymmetric Color Matching Adjusting! TestMatch

11 Task: Asymmetric Color Matching Adjusting! TestMatch

12 Task: Asymmetric Color Matching Adjusting! TestMatch

13 Task: Asymmetric Color Matching TestMatch Done!

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

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

16 Experimental Variables: Location, Material, Color Material Color Location

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

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

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

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

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

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

23 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.

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

25 Transformed Data Representation test mean

26 Transformed Data Representation test mean match

27 Transformed Data Representation test mean match

28 Transformed Data Representation test mean match

29 Transformed Data Representation test mean match

30 Transformed Data Representation test mean match

31 Soccer Ball Experiment, More Data

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

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

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

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

36 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.

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

38 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.

39 Design: Test Patch Location Effect

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

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

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

43 CIELAB Representation of Test Stimuli

44 LEI Histograms, Compared with Residuals

45 Material Influence Index (LEI)

46

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

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

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

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

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

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

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

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


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