1. Announcements Final project presentations on Wednesday Each group has 10 minutes Place.ppt talk in artifact directory Final reports due on Friday at 11:59pm Web page (see project4 web page) Does not have to be long, but should be sufficient to describe what you did, related work, results, and discussion Evals at the end of class today

2. Matting and Transparency Slides adapted from Alexei Efros, Yung-Yu Chuang, and Shree Nayar

3. How does Superman fly? Super-human powers? OR Image Matting?

4. Digital matting Forrest Gump (1994)

5. Compositing  F B C foreground color alpha matte background plate composite compositing equation B F C  =0

6. Compositing  F B C composite compositing equation B F C  =1

7. Compositing  F B C composite compositing equation B F C  =0.6

8. Matting C observation compositing equation  F B

9. Matting C compositing equation  F B Three approaches: 1 reduce #unknowns 2 add observations 3 add priors

10. Matting (reduce #unknowns) C F BB difference matting 

11. Matting (reduce #unknowns) C F B blue screen matting 

12. Problems with color difference Background color is usually not perfect! (lighting, shadowing…)

13. Matting (add observations) F Smith & Blinn, 96  BC

14. Natural image matting BC Matting (add priors) F  B rotoscopingRuzon-Tomasi FG BG unknown

15. Bayesian framework f(z)+  zy para- meters observed signal Example: super-resolution de-blurring de-blocking …

16. Bayesian framework data evidence a-priori knowledge f(z)+  zy para- meters observed signal

17. Bayesian framework likelihood priors posterior probability

18. Priors

19. Bayesian matting

20. Optimization repeat until converge 1. fix alpha 2. fix F and B

29. inputtrimap alpha

30. input composite

31. Environment Matting and Compositing Video Douglas E. Zongker ~ Dawn M. Werner ~ Brian Curless ~ David H. Salesin

32. Fast Separation of Direct and Global Images Using High Frequency Illumination Shree K. Nayar Gurunandan G. Krishnan Columbia University SIGGRAPH Conference Boston, July 2006 Support: ONR, NSF, MERL Michael D. Grossberg City College of New York Ramesh Raskar MERL

33. source surface P Direct and Global Illumination A A : Direct B B : Interrelection C C : Subsurface D participating medium D : Volumetric translucent surface E E : Diffusion camera

34. direct global radiance Direct and Global Components: Interreflections surface i camera source j BRDF and geometry

35. High Frequency Illumination Pattern surface camera source fraction of activated source elements + i

36. High Frequency Illumination Pattern surface fraction of activated source elements camera source + - i

37. Separation from Two Images directglobal

38. Other Global Effects: Subsurface Scattering translucent surface camera source i j

39. Other Global Effects: Volumetric Scattering surface camera source participating medium i j

40. Diffuse Interreflections Specular Interreflections Volumetric Scattering Subsurface Scattering Diffusion

41. Scene

42. DirectGlobal

43. Real World Examples: Can You Guess the Images?

44. Eggs: Diffuse Interreflections DirectGlobal

45. Wooden Blocks: Specular Interreflections DirectGlobal

46. Kitchen Sink: Volumetric Scattering Volumetric Scattering: Chandrasekar 50, Ishimaru 78 DirectGlobal

47. Peppers: Subsurface Scattering DirectGlobal

48. Hand DirectGlobal Skin: Hanrahan and Krueger 93, Uchida 96, Haro 01, Jensen et al. 01, Cula and Dana 02, Igarashi et al. 05, Weyrich et al. 05

49. Face: Without and With Makeup GlobalDirect GlobalDirect Without Makeup With Makeup

50. Blonde Hair Hair Scattering: Stamm et al. 77, Bustard and Smith 91, Lu et al. 00 Marschner et al. 03 DirectGlobal

51. www.cs.columbia.edu/CAVE