4/23/2009 1 Computational Ill i ti Illumination Ramesh Raskar, Computational Illumination Computational Illumination Computational Illumination SIGGRAPH 2006 Course Course WebPage: Ramesh Raskar Mitsubishi Electric Research Labs http://www.merl.com/people/raskar/photo/ Ramesh Raskar, Computational Illumination Computational Illumination Edgerton 1930’s Edgerton 1930’s Not Special Cameras but Special Lighting Edgerton 1930’s Edgerton 1930’s Multi‐flash Sequential Photography Stroboscope (Electronic Flash) Shutter Open Flash Time Ramesh Raskar, Computational Illumination Computational Illumination: Computational Illumination: • Presence or Absence, Duration, Brightness Presence or Absence, Duration, Brightness – Flash/No Flash/No-flash flash • Light color/wavelength Light color/wavelength • Light Light position position – Multi Multi-flash for depth edges flash for depth edges – Programmable dome (image re Programmable dome (image re-lighting and matting) lighting and matting) • Spatial Spatial Modulation Modulation – Dual Photography Dual Photography
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SIGGRAPH 2006 Course Computational Ill i tiIllumination ... · Effect of Varying αin Spectral Term ... – Masking of shadows in dark flash image ... lighting) Visible flash Agnes
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–– MultiMulti--flash for depth edgesflash for depth edges–– Programmable dome (image reProgrammable dome (image re--lighting and matting)lighting and matting)
–– MultiMulti--flash for depth edgesflash for depth edges–– Programmable dome (image reProgrammable dome (image re--lighting and matting)lighting and matting)
Elmar Eisemann and Frédo Durand , Flash Photography Enhancement via Intrinsic Relighting
Georg Petschnigg, Maneesh Agrawala, Hugues Hoppe, Richard Szeliski, Michael Cohen, Kentaro Toyama. Digital Photography with Flash and No-Flash Image Pairs
Flash
No-flash
Result
Transfer detail from flash image to no-flash image
–– MultiMulti--flash for depth edgesflash for depth edges–– Programmable dome (image reProgrammable dome (image re--lighting and matting)lighting and matting)
–– MultiMulti--flash for depth edgesflash for depth edges–– Programmable dome (image reProgrammable dome (image re--lighting and matting)lighting and matting)
Ramesh Raskar, Karhan Tan, Rogerio Feris, Jingyi Yu, Matthew Turk
Mitsubishi Electric Research Labs (MERL), Cambridge, MAU of California at Santa BarbaraU of North Carolina at Chapel Hill
Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera
Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera
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Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera
Depth Discontinuities
Internal and externalShape boundaries, Occluding contour, Silhouettes
Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera
Our MethodCanny
Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera Mitsubishi Electric Research Labs Raskar, Tan, Feris, Yu, TurkMultiFlash NPR Camera
Photo Result
Canny Intensity Edge Detection
Our Method
Debevec et al. 2002: ‘Light Stage 3’Debevec et al. 2002: ‘Light Stage 3’
Ramesh Raskar, Computational Illumination
ImageImage--Based Actual ReBased Actual Re--lightinglighting
Film the background in Milan,Film the background in Milan,Measure incoming light,Measure incoming light,
Light the actress in Los AngelesLight the actress in Los AngelesDebevec et al., SIGG2001
Ramesh Raskar, Computational Illumination
Matte the backgroundMatte the background
Matched LA and Milan lighting.Matched LA and Milan lighting.
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A 4A 4--D Light SourceD Light Source
Ramesh Raskar, Computational Illumination[Debevec et al. 2002]
–– MultiMulti--flash for depth edgesflash for depth edges–– Programmable dome (image reProgrammable dome (image re--lighting and matting)lighting and matting)
Dual PhotographyDual PhotographyPhotocellProjector Camera
Scene
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camera
The 4D transport matrixThe 4D transport matrix::Contribution of each projector pixel to each camera pixelContribution of each projector pixel to each camera pixel
projector
scene
camera
The 4D transport matrix:The 4D transport matrix:Contribution of each projector pixel to each camera pixelContribution of each projector pixel to each camera pixel
projector
sceneSen et al, Siggraph 2005Sen et al, Siggraph 2005
camera
The 4D transport matrix:The 4D transport matrix:Which projector pixel contribute to each camera pixelWhich projector pixel contribute to each camera pixel
projector
??
sceneSen et al, Siggraph 2005Sen et al, Siggraph 2005
Simulation of spectral sensitivities of 5 channel dark flash Bayer pattern
Note that UV and IR channels are:(a) Only just outside visible (blue dashed lines)(b) Very narrow in width to prevent too much ambient UV and IR being picked up(c) Closely matched to emission spectrum of UV/IR flash provided by UV/IR LEDs (see next slide)
sitiv
ity
350 400 700 800500 600UV IR
Conventional R,G,B channels
Wavelength (nm)
Spec
tral s
ens
Simulation of emission spectrum of dark flash
ssio
n
UV LED emission IR LED emission
Notes:( )
350 400 700 800500 600UV IRWavelength (nm)
Spec
tral e
mis (a) UV LED emission must not be below
350nm for safety reasons(b) Spectral width of emissions should be
as narrow as possible, to couple withnarrow bandpass filter of sensor
Dark flash design for cellphone/camera
• Array of White LEDs, UV LEDs (shown in yellow) and IR LEDs (shown in magenta)
• White LEDs provided standard visible flash
/ id d k fl h• UV/IR LEDs provide dark flash
• LEDs are cheap/compact
Ultra‐Violet photography
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