Coded Photography - Ramesh Raskar

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  • 1. Coded Photography
  • 2. Light Field Inside a Camera Lenslet-based Light Field camera [Adelson and Wang, 1992, Ng et al. 2005 ]
  • 3. Stanford Plenoptic Camera [Ng et al 2005] Contax medium format camera Kodak 16-megapixel sensor Adaptive Optics microlens array 125μ square-sided microlenses 4000 4000 pixels 292 292 lenses = 14 14 pixels per lens
  • 4. Digital Refocusing [Ng et al 2005] Can we achieve this with a Mask alone?
  • 5. Mask based Light Field Camera Mask Sensor [Veeraraghavan, Raskar, Agrawal, Tumblin, Mohan, Siggraph 2007 ]
  • 6. Mask based Light Field Camera Mask Sensor
  • 7. Cosine Mask Used Mask Tile 1/f0
  • 8. Captured 2D Photo Encoding due to Mask [Veeraraghavan, Raskar, Agrawal, Tumblin, Mohan, Siggraph 2007 ]
  • 9. 2D FFT Traditional Camera Photo Magnitude of 2D FFT 2D FFT Heterodyne Camera Photo Magnitude of 2D FFT
  • 10. 2D Photo LED In Focus Photo
  • 11. Out of Focus Photo: Open Aperture
  • 12. Out of Focus Photo: Coded Aperture
  • 13. Captured Blurred Photo [Veeraraghavan, Raskar, Agrawal, Tumblin, Mohan, Siggraph 2007 ]
  • 14. Refocused on Person Increase DoF + large aperture
  • 15. Engineering the PSF when you cannot capture Lightfield Out of Focus Photo: Coded Aperture
  • 16. Digital Refocusing Captured Blurred Photo
  • 17. Digital Refocusing Refocused Image on Person
  • 18. Mask? Mask Digital Refocusing Sensor
  • 19. Mask? Mask Sensor Sensor Mask Digital Refocusing Heterodyne Light Field Camera
  • 20. 4D Light Field 2D Photo
  • 21. Computing 4D Light Field 2D Sensor Photo, 1800*1800 2D Fourier Transform 2D FFT 9*9=81 spectral copies Rearrange 2D tiles into 4D planes 4D IFFT 4D Light Field 200*200*9*9 200*200*9*9
  • 22. Mask = more information? Mask? Sensor Sensor Mask Digital Refocusing Sensor Mask Heterodyne Light Field Camera [Veeraraghavan, Raskar, Agrawal, Tumblin, Mohan], Sig graph 2007
  • 23. MERL Veeraraghavan, Raskar, Agrawal, Mohan & Tumblin Mask-Enhanced Cameras: Heterodyned Light Fields & Coded Aperture Differences with Plenoptic Camera Sensor Sensor Microlens array Plenoptic Camera Mask Heterodyne Camera • Micro-lens array • Narrowband Cosine Mask • Samples individual rays • Samples coded comb of rays • Needs alignment precision • More flexible • Some pixels wasted • No wastage - Half brightness, diffraction
  • 24. Novel Sensors • Color – Foveon • Dynamic Range – HDR Camera, Log sensing – Gradient sensing • Identity – Demodulation • 3D – ZCam, Canesta • Motion – Line scan Camera – Flutter Shutter
  • 25. Foveon: All Colors at a Single Pixel
  • 26. High Dynamic Range Fuji's SuperCCD S3 Pro Sensor with high and low sensitivity sensors per pixel location
  • 27. Gradient Camera • Sense Pixel Intensity Difference with unknown locally adaptive gain • Reconstruct image from 2D gradient field Ramesh Raskar, MERL Work with Jack Tumblin, Northwestern U, Amit Agrawal, U of Maryland
  • 28. High Dynamic Range Images Scene Intensity camera saturation map Gradient camera saturation map Intensity camera fail to capture range Gradients saturate at very few isolated pixels
  • 29. Natural Scene Properties Intensity Gradient 105 105 1 1 x x Intensity Histogram 1 105 Gradient Histogram -105 105
  • 30. Motion _ _
  • 31. Line Scan Camera: PhotoFinish 2000 Hz
  • 32. Figure 2 results Photo with motion blur
  • 33. Rectified Image to make motion lines parallel to scan lines.
  • 34. Approx Cut-out Image Deblurred by solving a linear system.
  • 35. Fluttered Shutter Camera [Raskar, Agrawal, Tumblin] Siggraph2006
  • 36. Coded Exposure Temporal 1-D broadband code Coded Aperture Spatial 2-D broadband code
  • 37. Novel Sensors • Color – Foveon • Dynamic Range – HDR Camera, Log sensing – Gradient sensing • Identity – Demodulation • 3D – ZCam, Canesta • Motion – Line scan Camera – Flutter Shutter
  • 38. Perspective? Or Not? Rademacher et al, MCOP, Siggraph 1998 Agrawala et al, Long Scene Panoramas, Siggraph 2006
  • 39. Multiperspective Camera? [ Jingyi Yu‟ 2004 ]
  • 40. Future .. • „Cloth-cam‟: „Wallpaper-cam‟ – Fusion of 4D light emission and 4D capture in the surface of a cloth… • Human Augmentation – Cameras to replace human eyes, for blind or limited vision – Camera on the „back‟ • More Sensors – GPS, Compass, Temperature, fingerprint recognition, face recognition – When, Where, What, How .. Why? • Photo Sharing and Community: – Photo Clip and Scene Completion – City Scanning, Live
  • 41. Light Sensitive Fabric Bayindir, Fink 2004
  • 42. Computational Photography Novel Illumination Light Sources Novel Cameras Modulators Generalized Optics Generalized Sensor Processing Ray Reconstruction Generalized Optics 4D Incident Lighting 4D Ray Bender Upto 4D Ray Sampler 4D Light Field Display Recreate 4D Lightfield Scene: 8D Ray Modulator
  • 43. Fixed Color Gamut G R ≈ 0.0 G ≈ 0.2 R B B ≈ 0.8
  • 44. Wider color gamut G 400nm R 550nm 700nm λ “Best” primaries compromise: Wide Gamut vs. High Power B
  • 45. Adaptive Color Primaries
  • 46. Agile Spectrum Imaging With Ankit Mohan, Jack Tumblin [Eurographics 2008]
  • 47. Rainbow Plane inside Camera Pinhole Scene Lens L2 Lens L1 C C‟ ‟ A‟ B B‟ A Sensor B‟ ‟ C‟ Prism or Diffraction Grating Rainbow Plane A‟ ‟
  • 48. Computational Photography 1. 2. Epsilon Photography – Low-level vision: Pixels – Multi-photos by perturbing camera parameters – HDR, panorama, … – ‘Ultimate camera’ Coded Photography – – – – 3. Mid-Level Cues: • Regions, Edges, Motion, Direct/global • Reversible encoding of data Single/few snapshot Additional sensors/optics/illum ‘Scene analysis’ Essence Photography – High-level understanding – • • Not mimic human eye Beyond single view/illum ‘New artform’