Raspberry Pi 5: Challenges and Solutions in Bringing up an OpenGL/Vulkan Driv...
Raskar Coded Opto Charlotte
1. Mitsubishi Electric Research Laboratories Raskar 2007
Media Lab, MIT
Cambridge, MA
Less is More:Less is More:
Coded Computational PhotographyCoded Computational Photography
Ramesh Raskar
P r o j e c t o r
T a g s
P o s = 0
P o s = 2 5 5
5. Short Exposure Traditional MURA
Deblurred
Result
Captured
Single
Photo
Shutter
Banding Artifacts and
some spatial frequencies
are lost
Dark
and noisy
7. Flutter Shutter: Shutter is OPEN and CLOSED
Preserves High Spatial
Frequencies
Sharp Photo Blurred Photo
PSF == Broadband Function
Fourier
Transform
8. Flutter Shutter CameraFlutter Shutter Camera
Raskar, Agrawal, Tumblin [Siggraph2006]
LCD opacity switched
in coded sequence
12. Coded Aperture CameraCoded Aperture Camera
The aperture of a 100 mm lens is modified
Rest of the camera is unmodified
Insert a coded mask with chosen binary pattern
18. Less is MoreLess is More
Blocking Light == More InformationBlocking Light == More Information
Coding in TimeCoding in Time Coding in SpaceCoding in Space
19. Less is More ..Less is More ..
• Coded Exposure
– Motion Deblurring [2006]
• Coded Aperture
– Focus Deblurring [2007]
• Optical Heterodyning
– Light Field Capture [2007]
• Coded Spectrum
– Agile Wavelength Profile [2008]
• Coded Illumination
– Motion Capture [2007]
– Multi-flash: Shape Contours [2004]
P r o je c t o r
T a g s
P o s = 0
P o s = 2 5 5
20. Computational PhotographyComputational Photography
1. Epsilon Photography
– Low-level vision: Pixels
– Multi-photos by perturbing camera parameters
– HDR, panorama, …
– ‘Ultimate camera’
1. Coded Photography
– Single/few snapshot
– Reversible encoding of data
– Additional sensors/optics/illum
– ‘Scene analysis’ : (Consumer software?)
1. Essence Photography
– Beyond single view/illum
– Not mimic human eye
– ‘New art form’
21. Computational PhotographyComputational Photography
1. Epsilon Photography
– Low-level Vision: Pixels
– Multiphotos by perturbing camera parameters
– HDR, panorama
– ‘Ultimate camera’
1. Coded Photography
– Mid-Level Cues:
• Regions, Edges, Motion, Direct/global
– Single/few snapshot
• Reversible encoding of data
– Additional sensors/optics/illum
– ‘Scene analysis’
1. Essence Photography
– Not mimic human eye
– Beyond single view/illum
– ‘New artform’
22. Computational PhotographyComputational Photography
1. Epsilon Photography
– Multiphotos by varying camera parameters
– HDR, panorama
– ‘Ultimate camera’: (Photo-editor)
1. Coded Photography
– Single/few snapshot
– Reversible encoding of data
– Additional sensors/optics/illum
– ‘Scene analysis’ : (Next software?)
1. Essence Photography
– High-level understanding
• Not mimic human eye
• Beyond single view/illum
– ‘New artform’
25. Lenslet-based Light Field cameraLenslet-based Light Field camera
[Adelson and Wang, 1992, Ng et al. 2005 ]
Light Field Inside a CameraLight Field Inside a Camera
26. Stanford Plenoptic CameraStanford Plenoptic Camera [Ng et al 2005][Ng et al 2005]
4000 × 4000 pixels ÷ 292 × 292 lenses = 14 × 14 pixels per lens
Contax medium format camera Kodak 16-megapixel sensor
Adaptive Optics microlens array 125μ square-sided microlenses
28. Mask based Light Field Camera
Mask
Sensor
[Veeraraghavan, Raskar, Agrawal, Tumblin, Mohan, Siggraph 2007 ]
29. How to Capture
4D Light Field with
2D Sensor ?
What should be the
pattern of the mask ?
30. Radio Frequency HeterodyningRadio Frequency Heterodyning
Baseband Audio
Signal
Receiver: DemodulationHigh Freq Carrier
100 MHz
Reference
Carrier
Incoming
Signal
99 MHz
31. Optical HeterodyningOptical Heterodyning
Photographic
Signal
(Light Field)
Carrier Incident
Modulated
Signal
Reference
Carrier
Main LensObject Mask Sensor
Recovered
Light
Field
Software Demodulation
Baseband Audio
Signal
Receiver: DemodulationHigh Freq Carrier
100 MHz
Reference
Carrier
Incoming
Signal
99 MHz
34. Computing 4D Light Field
2D Sensor Photo, 1800*1800 2D Fourier Transform, 1800*1800
2D
FFT
Rearrange 2D tiles into 4D planes
200*200*9*94D IFFT
4D Light Field
9*9=81 spectral copies
200*200*9*9
35. A Theory of Mask-Enhanced CameraA Theory of Mask-Enhanced Camera
Main LensObject Mask Sensor
•Mask == Light Field Modulator
•Intensity of ray gets multiplied by Mask
•Convolution in Frequency domain
50. Full resolution 2D image
of Focused Scene Parts
Captured
2D Photo
Image of White Lambertian
Plane
divide
51. Coding and Modulation in Camera Using MasksCoding and Modulation in Camera Using Masks
Mask? Sensor
Mask
Sensor
Mask
Sensor
Coded Aperture for
Full Resolution
Digital Refocusing
Heterodyne Light
Field Camera
How is the blurred image formed? It’s a convolution with box filter
Coded exposure makes the filter broadband
Comparisons
License plate example: Blur = 60 pixels
Can you guess what the car make is ? How many think it is the Audi ? Actually it is a Folksvagon.
Cannot handle edges in blur
2D result
Reversibly encode all the information in this otherwise blurred photo
The glint out of focus shows the unusual pattern.
Difficult to argue that the worm is performing high quality deconvolution to form an image. But in our group we are setting up experiments by creating active lighting probe to understand how worms perform visual analysis.
Talk about limitations: Colocated artifacts, color coherency, ref can’t be obtain by subtraction
Stereo-pair is a simple example of coded photography.
Many decomposition problems, direct/global, diffuse/specular,
Inference and perception are important. Intent and goal of the photo is important.
The same way camera put photorealistic art out of business, maybe this new artform will put the traditional camera out of business. Because we wont really care about a photo, merely a recording of light but a form that captures meaningful subset of the visual experience. Multiperspective photos. Photosynth is an example.
Maybe all the consumer photographer wants is a black box with big red button. No optics, sensors or flash.
If I am standing the middle of times square and I need to take a photo. Do I really need a fancy camera?
The camera can trawl on flickr and retrieve a photo that is roughly taken at the same position, at the same time of day. Maybe all the consumer wants is a blind camera.