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Exploring Light Field Technology: Applications and Innovations

Learn about light field technology, including its applications and benefits in capturing coherent images, wave optics effects, and augmented light fields. Discover how light fields can be used in computational photography and beyond.

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Exploring Light Field Technology: Applications and Innovations

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  1. Light Field = Array of (virtual) Cameras Sub-aperture Virtual Camera = Sub-aperture View

  2. Samples individual rays Predefined spectrum for lenses Chromatic abberration High alignment precision Peripheral pixels wasted pixels Negligible Light Loss Samples coded combination of rays Supports any wavelength Reconfigurable f/#, Easier alignment No wastage High resolution image for parts of scene in focus 50 % Light Loss due to mask Sensor Mask Sensor Microlens array Plenoptic Camera Heterodyne Camera

  3. θ l(x,θ) θ x x l(x,θ) x1’ = x1 + θi*z θi θj x1 θj x2 Shear of Light Field θi θj x2 x1 x1 x'1

  4. L(fx,fθ) l(x,θ) l(x,θ) θ θ fθ 2-D FFT x x fx Central Slice Line Integral 1-D FFT 1-D FFT Light Propagation (Defocus Blur) Captured Photo FFT of Captured Photo

  5. Space of LF representationsTime-frequency representations Phase space representations Quasi light field Other LF representations WDF Augmented LF Observable LF Other LF representations Traditional light field incoherent Rihaczek Distribution Function coherent

  6. Quasi light fieldsthe utility of light fields, the versatility of Maxwell Other LF representations • We form coherent images by • formulating, • capturing, • and integrating • quasi light fields. WDF Augmented LF Observable LF Other LF representations Traditional light field incoherent Rihaczek Distribution Function coherent

  7. direction u aperture position s (i) Observable Light Field • move aperture across plane • look at directional spread • continuous form of plenoptic camera scene

  8. light field transformer LF LF LF LF negative radiance (diffractive) optical element LF propagation LF propagation (ii) Augmented Light Field with LF Transformer WDF Augmented LF Light Field Interaction at the optical elements

  9. Virtual light projector with real valued (possibly negative radiance) along a ray first null (OPD = λ/2) real projector virtual light projector real projector

  10. (ii) ALF with LF Transformer

  11. (iii) Rihaczek Distribution FunctionTradeoff between cross-interference terms and localization u y (i) Spectrogram non-negative localization (ii) Wigner localization cross terms (iii) Rihaczek localization complex 3 m u 0 m y y y 0 m 3 m 0 m 3 m 0 m 3 m

  12. Property of the Representation

  13. Benefits & Limitations of the Representation

  14. Motivation • What is the difference between a hologram and a lenticular screen? • How they capture ‘phase’ of a wavefront for telescope applications? • What is ‘wavefront coding’ lens for extended depth of field imaging?

  15. Application - Wavefront Coding small change in blur shape cubic phase plate point in scene Dowski and Cathey 1995 same aberrant blur regardless of depth of focus

  16. Can they be part of Computer Vision?Moving away from 2D images or 4D lightfields? Rendering: New perspective projection methods Holography: Reference targets Wavefront coding: WLC mobile phone cameras Rotating PSF: Depth from defocus Gaussian beam lasers:Modern active illumination

  17. Computational Photography http://computationalphotography.org • Epsilon Photography • Low-level Vision: Pixels • Multiphotos by bracketing (HDR, panorama) • ‘Ultimate camera’ • Coded Photography • Mid-Level Cues: • Regions, Edges, Motion, Direct/global • Single/few snapshot • Reversible encoding of data, Lightfield • Additional sensors/optics/illum • ‘Smart Camera’ • Essence Photography • Not mimic human eye • Beyond single view/illum • ‘New artform’

  18. Resources • Website • http://scripts.mit.edu/~raskar/lightfields/ • Or follow http://cvpr2009.org tutorial pages • Key new papers • Wigner Distributions and How They Relate to the Light FieldZhengyun Zhang and Marc Levoy, ICCP 2009 (best paper) • Augmenting Light Field to Model Wave Optics Effects , Se Baek Oh, Barbastathis, Raskar (in Preparation) • Quasi light fields: extending the light field to coherent radiation , Anthony Accardi, Wornell (in Preparation) Rihaczek Distribution Function WDF Augmented LF Observable LF Traditional light field

  19. Acknowledgements • Darthmuth • Marcus Testorf, • MIT • Ankit Mohan, Ahmed Kirmani, Jaewon Kim • George Barbastathis • Stanford • Marc Levoy, Ren Ng, Andrew Adams • Adobe • TodorGeorgiev, • MERL • Ashok Veeraraghavan, AmitAgrawal

  20. Light Fields___ Camera Culture Ramesh Raskar MIT Media Lab http:// CameraCulture . info/

  21. Light Fields in Ray and Wave Optics Introduction to Light Fields: Ramesh Raskar Wigner Distribution Function to explain Light Fields: Zhengyun Zhang Augmenting LF to explain Wigner Distribution Function: Se Baek Oh Q&A Break Light Fields with Coherent Light: Anthony Accardi New Opportunities and Applications: Raskar and Oh Q&A: All

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