OUTLINEOUTLINE What is Photography? What is Photography? What is ‘The Photographic Signal’? What...
Transcript of OUTLINEOUTLINE What is Photography? What is Photography? What is ‘The Photographic Signal’? What...
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• What is Photography? What is Photography?
• What is ‘The Photographic Signal’? What is ‘The Photographic Signal’?
• Perfecting Film-Like Photography: Perfecting Film-Like Photography: Old Problems, New ApproachesOld Problems, New Approaches
• Photography Beyond Film: Photography Beyond Film: New Goals, Methods, ExpressionsNew Goals, Methods, Expressions
Course 15:
Computational PhotographyCourse 15:Course 15:
Computational Photography
Jack TumblinJack Tumblin
Northwestern UniversityNorthwestern University
A2:A2: Core ConceptsCore Concepts(15 minutes)(15 minutes)
Computational PhotographyComputational Photography
‘‘Film-Like’ PhotographyFilm-Like’ Photography‘‘Film-Like’ PhotographyFilm-Like’ Photography
Film Camera design assumptions:Film Camera design assumptions:
– ‘‘Instantaneous’ light measurement…Instantaneous’ light measurement…
– Of focal plane image behind a lens.Of focal plane image behind a lens.
– Reproduce those amounts of light.Reproduce those amounts of light.
Implied:Implied:
“ “What we see is What we see is focal-plane intensities.” focal-plane intensities.” well, no well, no…we see …we see muchmuch more! more!
(seeing is deeply cognitive)(seeing is deeply cognitive)
Our Definitions Our Definitions Our Definitions Our Definitions
• ‘‘Film-like’ Photography:Film-like’ Photography:
– Static ‘instantaneous’ record of Static ‘instantaneous’ record of the 2D image formed by a lensthe 2D image formed by a lens
Display image Display image sensor image sensor image
• ‘‘Computational’ Photography:Computational’ Photography:
– displayed image displayed image sensor image sensor image
– A more expressive, controllable displayed result,A more expressive, controllable displayed result,
from transformed, merged, decoded sensor datafrom transformed, merged, decoded sensor data
What What isis Photography? Photography?What What isis Photography? Photography?
• A ‘bucket’ word: a neat container for messy notionsA ‘bucket’ word: a neat container for messy notions(e.g. aviation, music, comprehension)(e.g. aviation, music, comprehension)
• A record of what we see,A record of what we see,or would like to see,or would like to see,in tangible form.in tangible form.
• Does ‘film’ photography Does ‘film’ photography always capture it? always capture it? no.
• So, what do we see?So, what do we see?Harold ‘Doc’ Edgerton 1936Harold ‘Doc’ Edgerton 1936
DisplayDisplayRGB(x,y,tRGB(x,y,tnn))
ImageImageI(x,y,I(x,y,λλ,t),t)
Light &Optics3D Scene3D Scene
light sources, BRDFs,shapes,
positions,movements,
…
EyepointEyepoint position,
movement,projection,
…
PHYSICALPHYSICAL PERCEIVEDPERCEIVED
What What isis Photography? Photography?
Exposure Exposure Control,Control,
tone maptone mapSceneScenelight sources,BRDFs,shapes,positions,movements,…
EyepointEyepointposition, movement,projection,…
Vis
ion
Photo: A Tangible RecordPhoto: A Tangible RecordEditable, storable asEditable, storable as
Film or PixelsFilm or Pixels
3D Scene?3D Scene?light sources, BRDFs,shapes,positions,movements,…
Eyepoint?Eyepoint?position, movement,projection,…
Meaning…Meaning…
VisualVisualStimulusStimulus
3D Scene3D Scenelight sources,
BRDFs,shapes,
positions,movements,
…
EyepointEyepoint position,
movement,projection,
…
PHYSICALPHYSICAL PERCEIVED PERCEIVED or UNDERSTOODor UNDERSTOOD
Ultimate Photographic GoalsUltimate Photographic Goals
Vis
ion
Vis
ion
Sen
sor(
s)S
enso
r(s)
Com
putin
gC
ompu
ting
Light &Light &OpticsOptics
Photo: A Tangible RecordPhoto: A Tangible RecordScene Scene estimates we canestimates we can
capture, edit, store, displaycapture, edit, store, display
Missing:Missing: Viewpoint Freedom Viewpoint Freedom
Missing:Missing: Viewpoint Freedom Viewpoint Freedom
““Multiple-Center-of-Projection Images” Rademacher, P, Bishop, G., SIGGRAPH '98Multiple-Center-of-Projection Images” Rademacher, P, Bishop, G., SIGGRAPH '98
Missing: Missing: Reliable Visual BoundariesReliable Visual Boundaries
Missing: Missing: Reliable Visual BoundariesReliable Visual Boundaries
5 ray sets 5 ray sets explicit geometric occlusion boundaries explicit geometric occlusion boundaries
Ramesh Raskar, MERL, 2004
Missing:Missing: Expressive Time ManipulationsExpressive Time Manipulations
Missing:Missing: Expressive Time ManipulationsExpressive Time Manipulations
What other waysWhat other waysbetter better revealreveal appearanceappearance to to human viewers?human viewers?
(Without direct shape (Without direct shape measurement? )measurement? )
Time for space wiggle. Time for space wiggle. Gasparini, 1998.
Can you understandCan you understand this shape better?this shape better?
Photographic Signal: Pixels RaysPhotographic Signal: Pixels RaysPhotographic Signal: Pixels RaysPhotographic Signal: Pixels Rays
• Core ideas are ancient, simple, seem obvious:Core ideas are ancient, simple, seem obvious:– Lighting: Lighting: ray sourcesray sources
– Optics:Optics: ray bending/folding devices ray bending/folding devices
– Sensor:Sensor: measure light measure light
– Processing:Processing: assess it assess it
– Display:Display: reproduce it reproduce it
• Ancient Greeks:Ancient Greeks:‘eye rays’ wipe the world‘eye rays’ wipe the worldto feel its contents…to feel its contents…
http://www.mlahanas.de/Greeks/Optics.htmhttp://www.mlahanas.de/Greeks/Optics.htm
The Photographic Signal PathThe Photographic Signal PathThe Photographic Signal PathThe Photographic Signal Path
Computing can improve every component:Computing can improve every component:
Light SourcesLight Sources SensorsSensorsData Types,Data Types,ProcessingProcessing
DisplayDisplayRaysRays
OpticsOpticsOpticsOptics
““Scene”Scene”RaysRays
Review: How many Rays in a 3-D Scene?Review: How many Rays in a 3-D Scene?Review: How many Rays in a 3-D Scene?Review: How many Rays in a 3-D Scene?
A 4-D set of infinitesimal members. A 4-D set of infinitesimal members.
Imagine:Imagine:
– Convex Enclosure of a 3D scene Convex Enclosure of a 3D scene
– Inward-facing ray camera at every surface pointInward-facing ray camera at every surface point
– Pick the rays you need for ANY camera outside.Pick the rays you need for ANY camera outside.
– 2D surface of cameras,2D surface of cameras,2D 2D ray set for each camera,ray set for each camera,
4D set of rays.4D set of rays.
(Levoy et al. SIGG’96)(Levoy et al. SIGG’96) (Gortler et al. ‘96) (Gortler et al. ‘96)
++
4-D Light Field / Lumigraph4-D Light Field / Lumigraph4-D Light Field / Lumigraph4-D Light Field / Lumigraph
Measure all the Measure all the outgoingoutgoing light rays. light rays.
4-D Illumination Field4-D Illumination Field4-D Illumination Field4-D Illumination Field
Same Idea: Measure all the Same Idea: Measure all the incomingincoming light rays light rays
4D x 4D = 8-D Reflectance Field4D x 4D = 8-D Reflectance Field4D x 4D = 8-D Reflectance Field4D x 4D = 8-D Reflectance Field
Ratio:Ratio: R Rijij = (outgoing ray = (outgoing rayii) / (incoming ray) / (incoming rayjj))
Future Photography:Future Photography:Novel IlluminatorsNovel Illuminators
Novel CamerasNovel Cameras
SceneScene: : 8D Ray Modulator8D Ray Modulator
Generalized Generalized SensorSensor
GeneralizedGeneralizedProcessingProcessing 4D Ray 4D Ray
SamplerSampler
Ray ReconstructorRay Reconstructor
General Optics:General Optics: 4D Ray Benders 4D Ray Benders
Recreated 4D Light fieldRecreated 4D Light field
LightsLights
ModulatorsModulators
4D Incident Lighting4D Incident Lighting
Vie
wed
4D
Lig
ht
Fie
ld
Vie
wed
4D
Lig
ht
Fie
ld
Ge
ner
al O
ptic
s:G
en
eral
Op
tics:
4D
Ray
Ben
der
s4D
Ray
Ben
der
s
Generalized DisplayGeneralized Display
Novel DisplaysNovel Displays
Expand Optics Into SoftwareExpand Optics Into SoftwareExpand Optics Into SoftwareExpand Optics Into Software
Programmable Optical Devices Programmable Optical Devices enable new forms of:enable new forms of:
[ Nayar ][ Nayar ]
• Omni-Directional Lens Systems Omni-Directional Lens Systems
(Hi-Def 360(Hi-Def 360oo video…) video…)
• ‘‘Assorted Pixels’ SensorsAssorted Pixels’ Sensors(Robust HDR, multispectral…)(Robust HDR, multispectral…)
• Lensless Adaptive-Aperture CamerasLensless Adaptive-Aperture Cameras (tracking without panning…)(tracking without panning…)
Expand Scientific / Medical ImagingExpand Scientific / Medical ImagingExpand Scientific / Medical ImagingExpand Scientific / Medical Imaging
4D light sources + 4D cameras 4D light sources + 4D cameras enable new forms of:enable new forms of:
[ Levoy ][ Levoy ]
• Synthetic Aperture Imaging Synthetic Aperture Imaging (see through trees…) (see through trees…)
• Tomography Tomography (3-D volumetric imaging…)(3-D volumetric imaging…)
• Confocal ScanningConfocal Scanning (look inside muddy water…)(look inside muddy water…)
‘‘The Ideal Photographic Signal’The Ideal Photographic Signal’‘‘The Ideal Photographic Signal’The Ideal Photographic Signal’
I CLAIM IT IS:I CLAIM IT IS:
All Rays? Some Rays? All Rays? Some Rays? ChangesChanges in Some Rays in Some Rays
Photographic ray space is vast and redundantPhotographic ray space is vast and redundant
>8 dimensions: 4D view, 4D light, time, >8 dimensions: 4D view, 4D light, time, ,,
? Gather only ‘? Gather only ‘visually significantvisually significant’ ray changes ?’ ray changes ?
? What rays should we measure ? ? What rays should we measure ?
? How should we combine them ?? How should we combine them ?
? How should we display them ?? How should we display them ?
Beyond ‘Film-Like’ PhotographyBeyond ‘Film-Like’ PhotographyBeyond ‘Film-Like’ PhotographyBeyond ‘Film-Like’ Photography
Call itCall it ‘Computational Photography’: ‘Computational Photography’:
To make ‘meaningful ray changes’To make ‘meaningful ray changes’ tangible, tangible,
• OpticsOptics can do more… can do more…
• Sensors Sensors can do more… can do more…
• Light SourcesLight Sources can do more… can do more…
• ProcessingProcessing can do more… can do more…
by applying low-cost storage, by applying low-cost storage, computation, and control. computation, and control.
Course 15:
Computational PhotographyCourse 15:
Computational PhotographyA.2: ConceptsA.2: Concepts Tumblin Tumblin