Wavelengths and Colors. Ankit Mohan MAS.131/531 Fall 2009

Transcription

1 Wavelengths and Colors Ankit Mohan MAS.131/531 Fall 2009

2 Epsilon over time (Multiple photos) Prokudin-Gorskii, Sergei Mikhailovich, , photographer. Congress.

3 Epsilon over time (Bracketing) Image courtesy of shannonpatrick17 on Flickr. Color wheel used in DLP projectors

4 Epsilon over sensors 3CCD imaging system for color capture Images: Left Wikipedia User:Cburnett. Upper right Wikipedia User:Xingbo. License CC BY-SA. This content is ecluded from our Creative Commons license. For more information, see Lower right, public domain image by Dick Lyons.

5 Epsilon over piels Bayer Mosaicing for color capture Images: Wikipedia. Wikipedia User:Cburnett. License CC BY-SA. This content is ecluded from our Creative Commons license. For more information, see Demosaicing to interpolate a full color, high resolution image Source: Wikipedia Wikipedia User:Cburnett. License CC BY-SA. This content is ecluded from our Creative Commons license. For more information, see

6 Color sensing in Digital Cameras Nikon dichroic mirrors Foveon X3 sensor Image: Wikipedia. Wikipedia User:Anoneditor. License CC BY-SA. This content is ecluded from our Creative Commons license. For more information, see

7 Electromagnetic spectrum Visible Light: ~ nm wavelength Source: NASA

8 Spectroscope [ Images: Left Wikipedia User:Kkmurray. Right Wikipedia User:Deglr6328. License CC BY-SA. This content is ecluded from our Creative Commons license. For more information, see

9 Multispectral Imaging Image removed due to copyright restrictions. In Klemas Remote Sensing and Geospatial Technologies for Coastal Ecosystem Assessment. Edited by Xiaojun Yang. Springer, Preview in Google Books.

10 Multispectral Scanning (data cube) Diagram removed due to copyright restrictions.

11 Thermal Imaging [ Glass is opaque; use Germanium lenses Set of Thermal Imaging photos removed due to copyright restrictions.

12 Thermal Imaging Courtesy of Paul Falstad. Used with permission. [ Two photos removed due to copyright restrictions. [Pavlidis et al., Nature 2002]

13 Near Infrared Photography Four photos removed due to copyright restrictions.

14 Remote Sensing Images removed due to copyright restrictions.

15 Quartz lenses UV photography [ Si flower photos removed due to copyright restrictions.

16 CIE 1931 Chromaticity Diagram

17 Fied color primaries G srgb color space Fuji Velvia 50 film Nikon D70 camera R B

18 Outside the Color Gamut G R =? G =? R B =? B

19 Colorimetric or Photometric mapping G R 0.0 R B

20 Wide Color Gamut G 400nm 550nm 700nm R Wide Gamut vs. High Power B

21 Adaptive Color Primaries

22 Arbitrary white 1D signal I A B C I 400nm 550nm 700nm

23 Pinhole Camera C I B I A Object Image Pinhole

24 C B I A Object Lens L 1 Pinhole

25 C B I A Object Lens L 1 Prism Pinhole

26 Prism Spectral Light Field

27 Light-Field Placing a 1D screen in a 2D light-field gives a 1D projection in a direction perpendicular to the screen.

28 Prism I Screen I p

29 Prism I I p

30 I Prism t= p I t

31 Prism Lens L 2 I t S

32 Prism Lens L 2 I t t S

33 Prism Lens L 2 I t t R t S

34

35 Sensor plane (t=t s ) t t S I p

36 Rainbow plane (t=t R ) p All rays of the a given wavelength, from all points in the scene, converge to a unique point in the R-plane. I t t R

37 Rainbow plane (t=t R ) I p I 400nm 550nm 700nm I

38 Rainbow plane (t=t R ) I p I 400nm 550nm 700nm I

39 Rainbow plane (t=t R ) I p I R 400nm 550nm 700nm I I B 400nm 550nm 700nm

40 Rainbow plane (t=t R ) position t t R

41 Mask in the Rainbow plane X 0 t t R 1

42 Mask in the Rainbow plane 0 t t R

43 Mask in the Rainbow plane 0 t t R t S I p

44 Mask in the Rainbow plane 0 t t R t S I p

45 Mask in the Rainbow plane 0 t t R t S I p

46 Mask in the Rainbow plane 0 0 t t R t S I p

47 Rainbow plane (t=t R ) Control the spectral sensitivity of the sensor by placing an appropriate grayscale masks in the R-plane. t t R t S

48 Scene C Pinhole Lens L 1 Lens L 2 Sensor B A Prism or Diffraction Grating R-plane mask

49 Scene Pinhole Lens L 1 Lens L 1 Lens L 2 Sensor Prism or Diffraction Grating R-plane mask

50 Scene Aperture and Lens L 1 Lens L 2 Sensor Prism or Diffraction Grating R-plane mask

51 Diffraction R-plane Lens L 1 Grating Lens L 2 mask Sensor Mohan, A., R. Raskar, and J. Tumblin. Agile Spectrum Imaging: Programmable Wavelength Modulation for Cameras and Projectors. Proceedings of Eurographics 2008.

52 Test Setup Agile Spectrum Camera

53 m() 400nm 550nm No Mask 700nm m() 400nm 550nm 700nm Two opaque stripes One opaque stripe m() 400nm 550nm 700nm

54 m() 400nm 550nm 700nm Mohan et al. Eurographics 2008.

55

56 m() 400nm 550nm 700nm

57 Lens L 1 Diffraction Grating Lens L 2 R-plane mask Screen Mohan et al. Eurographics 2008.

58 Metamers White Illumination Monochromatic Illumination Mohan et al. Eurographics 2008.

59 Traditional three primary projector Mohan et al. Eurographics Agile-spectrum projector

60 Traditional three primary projector P y time

61 Adaptive primary projector P y time

62 Deuteranope red/green color blindness White light Deuteranope simulation Magenta light Mohan et al. Eurographics 2008.

63 Limitations Relatively coarse control due to crude setup with off-the-shelf components. Diffraction artifacts. Small F-number of the objective lens (we used ~f/16). Chromatic artifacts in out-of-focus regions for the projector.

64 Improved design Future work Mask instead of pinhole at L 1 Mask and Lens L 1 Better optics (LCD/DMD) and calibration Applications Adaptive color primaries Stereo projector Diffraction R-plane Grating Lens L 2 mask Sensor I 400nm B l G l R I l B r G r R r 550nm Left eye 700nm 400nm 550nm Right eye 700nm

65 Overlapping Light Fields Prism ( 0, 0 ) B A

66 Overlapping Light Fields Prism B A

67 Diffuse, fronto-parallel case Prism B A

68 Blurred Light Fields Prism B A Convolution of spectral light field with a bo filter

69 Pinhole multi-spectral camera Pinhole Scene C B A 2 Lens L Prism Light field camera

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71 Rainbow multi-spectral camera Scene C A Lens L 1 Linear Variable Interference Filter Light field camera

72 Mask based multi-spectral camera Scene C A Lens L 1 Mask, m() Prism Light field camera

73 MIT OpenCourseWare MAS.531 Computational Camera and Photography Fall 2009 For information about citing these materials or our Terms of Use, visit: