Signal ProcessingSignal Processingforfor

Computational ImagingComputational Imaging

Minh N. DoDepartment of Electrical and Computer Engineering

University of Illinois at Urbana-Champaign

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20 Greatest Engineering Achievements20 Greatest Engineering Achievements of the 20th Century of the 20th Century

Selected by the U.S. National Academy of Engineeringwww.greatachievements.org

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1. Electrification2. Automobile3. Airplane4. Water Supply and

Distribution5. Electronics6. Radio and Television7. Agricultural Mechanization8. Computers9. Telephone10.Air Conditioning and

Refrigeration

11.Highways12.Spacecraft13. Internet14. Imaging15.Household Appliances16.Health Technologies17.Petroleum and

Petrochemical Technologies18.Laser and Fiber Optics19.Nuclear Technologies20.High-performance Materials

20 Greatest Engineering Achievements20 Greatest Engineering Achievements of the 20th Century of the 20th Century

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ImagingImaging

• In 1900…• Only simple microscopes, telescopes, and

black and white photographs.

• In 2000…• Color photographs, movies, and television• New sensors that greatly expand our “vision”

• see tiny atomic particles to vast galaxies• see inside the human body• track weather patterns, …

• The entire microelectronics revolution is basedupon imaging

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ImageImage

FormationFormation

ImageImage

ProcessingProcessing

• Examples: optical imaging, radar imaging, computer tomography(CT), magnetic resonance imaging (MRI).

Imaging = Image Formation + ProcessingImaging = Image Formation + Processing

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Synthetic Aperture Radar (SAR)Synthetic Aperture Radar (SAR)

www.sandia.gov/RADAR

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Computer Tomography (CT)Computer Tomography (CT)

www.imaginis.com/ct-scan

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Magnetic Resonance Imaging (MRI)Magnetic Resonance Imaging (MRI)

www.uic.edu/com/mrc/

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Optical Coherence Tomography (OCT)Optical Coherence Tomography (OCT)

bil.nb.uiuc.edu

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ImageImage

FormationFormation

ImageImage

ProcessingProcessing

Imaging = Image Formation + ProcessingImaging = Image Formation + Processing

Tradition scope ofTradition scope ofsignal processingsignal processing

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Computational PhotographyComputational Photography

www.merl.com/people/raskar/photo/

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Imaging is a Multidisciplinary FieldImaging is a Multidisciplinary FieldAnd Signal Processing is the GlueAnd Signal Processing is the Glue

MathematicsMathematics PhysicsPhysics

ApplicationApplication

domaindomain

ComputerComputer

ScienceScience

ComputationalComputational

ImagingImaging

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An Application Domain: Health CareAn Application Domain: Health Care

• In 2005, the U.S. spent 16% of its GDP on health care.It is projected that this will reach 20% by 2015.• Starbucks: healthcare cost exceeds coffee.• General Motor: healthcare cost exceeds steel.

• A quarter of total Medicare budget is spent in the last year of life;40% of it is on the last 30 days.

Goal: Individualized treatments based on better medical imaging

• In developing countries: desire to have low-cost and effectivepopulation screening.

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Hardware Approach toHardware Approach toImaging System CalibrationImaging System Calibration

• Require expensive hardware modification and calibration

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Computational Approach to CalibrationComputational Approach to Calibration• Apply signal processing methods to form useful imagery from

imperfect signal measurements.• Use computational power to overcome physical limitations.

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MRI with Field MRI with Field InhomogeneityInhomogeneity

• Field inhomogeneity is a key factor affecting MRI image reconstruction

datadata imageimagefield mapfield map

HarmonicHarmonicRetrieval !Retrieval !

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Joint Estimation in MRI usingJoint Estimation in MRI usingHarmonic Retrieval MethodsHarmonic Retrieval Methods

Original image

and field mapStandard

reconstructionOur reconstruction

H. Nguyen et al., 2007H. Nguyen et al., 2007

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Autofocus Autofocus Problem inProblem inSynthetic Aperture Radar (SAR)Synthetic Aperture Radar (SAR)

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MCA: MCA: MultiChanel AutofocusMultiChanel Autofocus

wherewhere

R. Morrison et al., 2007R. Morrison et al., 2007

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Beyond TelevisionBeyond Television…… Remote Reality Remote Reality

M. Maitre et al., 2007M. Maitre et al., 2007

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Multi-Channel SamplingMulti-Channel Sampling

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Minimax Minimax Design of Hybrid Filter BanksDesign of Hybrid Filter Banks

H. Nguyen and MD, 2007H. Nguyen and MD, 2007

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Image Processing:Image Processing:The Key is Efficient Image RepresentationThe Key is Efficient Image Representation• Goal: Parsimonious view of pictorial information

A A naturalnatural image image A A randomrandom image imageA A biologicalbiological image image

Natural images Natural images ““livelive”” in a very tiny bit in a very tiny bit

of the space of all possible of the space of all possible ““imagesimages””

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OriginalOriginal domain: pixels domain: pixels WaveletWavelet domain: coefficients domain: coefficients

Image Representation via TransformsImage Representation via Transforms

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Example of Impact on ApplicationsExample of Impact on Applications

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Are We There?Are We There?

“…the 20 bits per second which, the psychologists assure us, thatthe human eye is capable of taking in…”

D. Gabor, 1959

One image Human eye (≈ 5 sec.) 100 bits

One imageJPEG-2000 (wavelets)

1’000’000 bits

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What Have We Learnt from Sputnik?What Have We Learnt from Sputnik?

“The lesson of the past 50 years, however, is that the more humanitydiscovers about space, the rarer and more precious life on Earthseems.”

Economists, 27 Sep 2007

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End of Part 1End of Part 1

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Part 2Part 2

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Martin NumberMartin Number

From ISI Web of Science: Distinct Author Summary -- Vetterli M

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Happy Birthday Martin!Happy Birthday Martin!