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Am I Blue? 30 January 2011 (v. 2.0) Brian C. Madden, Ph.D. Department of Dermatology University of Rochester.

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Presentation on theme: "Am I Blue? 30 January 2011 (v. 2.0) Brian C. Madden, Ph.D. Department of Dermatology University of Rochester."— Presentation transcript:

1 Am I Blue? 30 January 2011 (v. 2.0) Brian C. Madden, Ph.D. Department of Dermatology University of Rochester

2 Interaction of Light and Tissue Physics of light Optics of skin Models of light transport in skin Perceptual influences Example: The appearance of veins in vivo

3 Physics of Light Wave nature Particle nature

4 The Particle Nature of Light

5 The Wave Nature of Light

6 Optical Effects Transmission Reflection Absorption Scattering

7 Transmission (Refraction)

8 Reflection

9 Bidirectional Reflectance Distribution Function

10 Surface Effects on the BRDF Geometry of normals Multiple reflections Total internal reflection

11 Polarization Circular Linear

12 Fresnel Reflection

13 Absorption Beer’s Law

14 Chromophores of the Skin

15 Measured Hemoglobin Spectra

16 Scattering Tyndall Rayleigh Mie Thomson

17 Structural Blue

18 Other Sources of Blue

19 Mammalian Blue

20 Blue Lesions

21 3D Models of the Skin Uniform slab Serial reconstruction Wellman Lab (Anderson & Parrish, 1981) Hokkaido (Matsumura et al 1999) Yale (Braverman et al, 1986) UC Irvine (Smithies et al, 1997)

22 The Neapolitan Model of Skin

23 Models of Light Transport Kubelka-Munk diffusion Monte Carlo simulation Every model is the embodiment of a trade between computational convenience and reality

24 Kubelka - Munk Diffusion

25 Monte Carlo Simulation

26 3D Models of the Skin Uniform slab Serial reconstruction Wellman Lab (Parrish & Anderson, 1981) Hokkaido (Matsumura et al 1999) Yale (Braverman et al, 1986) UC Irvine (Smithies et al, 1997)

27 Cherry Angioma Model

28 3D Models of the Skin Uniform slab Serial reconstruction Wellman Lab (Parrish & Anderson, 1981) Hokkaido (Matsumura et al 1999) Yale (Braverman et al, 1986) UC Irvine (Smithies et al, 1997)

29 Port Wine Stain Model (0.8 MB)

30 3D Models of the Skin Uniform slab Serial reconstruction Wellman Lab (Parrish & Anderson, 1981) Hokkaido (Matsumura et al 1999) Yale (Braverman et al, 1986) UC Irvine (Smithies et al, 1997) (0,6MB) (0.4MB) (1.4MB)

31 Optical/Biological/Psychological Influences Absorption Scattering Anatomy Physiology Perception

32 What is physically different about blue veins? Vein depth in dermis diffuses borders Vein depth in dermis supports accumulation of superimposed scatter Vein diameters are sufficiently large to concentrate hemoglobin Hemoglobin absorption in veins is sufficient to visibly reduce total backscatter at the surface

33 Perceptual Influences Chromatic sensitivity Spatial Contrast sensitivity HVS nonlinearities Simultaneous brightness contrast Simultaneous color contrast

34 Perceptual Examples

35 Skin Tones

36 Skin and Edges

37 Sample image Do you trust what you see?

38 Macro view Should you?

39

40

41 p

42 Skin Reflectance Samples H S B area

43 Reflectance Differences S B B S

44

45 Simultaneous Contrast Distribution

46 Unresolved Issues Contributions of hematocrit and oxygenation Pressure and flow related sedimentation and clustering Erythrocyte scattering model Dermatoglyphic patterns and surface hydration Fresnel reflection and backscatter contribution Diffuse vein segmentation Structure of dermal vasculature

47 Sample image Is this the same image you viewed 11 slides ago?

48 Sample image redux Do you still trust what you see?

49 Sample image redux Do you still trust what you see?

50 Sample image redux Do you still trust what you see?

51 Sample image redux Do you still trust what you see?

52 Sample image redux Do you still trust what you see?

53 Sample image redux Do you still trust what you see?

54 Sample image redux Do you still trust what you see?

55 Sample image redux Do you still trust what you see?

56 Sample image redux Do you still trust what you see?

57 Sample image redux Do you still trust what you see?

58 Sample image redux Do you still trust what you see?

59 Summary and Conclusions Differential absorption leads to simultaneous contrast Differential scatter leads to desaturation Vein depth leads to a diffuse surface profile Taken together they promote a color contrast effect Expectation transforms a collection of weak effects into a substantial perceptual change

60 Interpreting a diagnostic image How much should you trust your vision when you need to be right?

61 So … am I blue?


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