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BME1450 – Biomedical Engineering 2002. Basic Image Display and Processing Linear Systems and Imaging Optical Microscopy X-ray Magnetic Resonance Imaging Ultrasound Nuclear Medical Electron Microscopy Scanning Probe Microscopy.

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bme1450 biomedical engineering 2002

BME1450 – Biomedical Engineering 2002

Basic Image Display and Processing

Linear Systems and Imaging

Optical Microscopy

X-ray

Magnetic Resonance Imaging

Ultrasound

Nuclear Medical

Electron Microscopy

Scanning Probe Microscopy

BME 1450 - 2002

basic image display greyscale
Basic Image Display Greyscale
  • Measurements displayed as colors or shades of gray.
  • Pixels or voxels.
  • Axes unusual
  • Colour maps

BME1450 - 2002

basic image display pseudo colour
Basic Image DisplayPseudo Colour
  • Max 105 :white
  • Min 0 :black
  • (R, G, B)
  • Contrast
  • Histogram
  • 4x104 :white
  • 2.5x104 :black

BME1450 - 2002

basic image display contrast enhanced
Basic Image DisplayContrast enhanced
  • Note colour bar range 2.5e4 to 4e4.
  • Higher contrast
  • More noise

BME1450 - 2002

basic image display median filtered
Basic Image DisplayMedian Filtered
  • Median Filter
  • Less spatial resolution

BME1450 - 2002

basic image display noise
Basic Image DisplayNoise
  • Find the disk objects.
  • 32x32 pixels
  • R = 3 pixels
  • 100 photons /pixels
  • + - 10
  • Poisson

BME1450 - 2002

basic image display rose s criterion
Basic Image DisplayRose’s Criterion
  • Rose’s hypothesis is that the human will do as well as the best machine when both human and machine are given the same task and a priori information.
  • N equals sum of the pixels in the region where the disk may be.
  • The machine knows average N = NBG if the disk is present and NOB if it is absent.

BME1450 - 2002

basic image display machine detection
Basic Image DisplayMachine Detection
  • N equals sum of the pixels in the region where the disk may be.
  • The machine knows average N = NBG if the disk is present and NOB if it is absent.
  • The machine says "present" if N > (NOB + NBG)/2 and "absent" otherwise.
  • I chose cases for which the machine's probability of false positive is the same.

BME1450 - 2002

basic image display equally visible
Basic Image DisplayEqually Visible?
  • Now R = 7 pixels.
  • Disks have same visibility to the machine.
  • Their contrast is reduced.
  • Are they as easy to spot as the R=3?

BME1450 - 2002

bme1450 biomedical engineering 20021

BME1450 – Biomedical Engineering 2002

Basic Image Display and Processing

Linear Systems and Imaging

Optical Microscopy

X-ray

Magnetic Resonance Imaging

Ultrasound

Nuclear Medical

Electron Microscopy

Scanning Probe Microscopy

BME 1450 - 2002

linear systems and imaging spatial invariance
Linear Systems and ImagingSpatial Invariance
  • Spatially Invariant

BME1450 - 2002

linear systems and imaging convolution integral
Linear Systems and ImagingConvolution Integral

The convolution integral

  • h(x,y) is the “point response function”
  • It is the image of a delta function.
  • It is translated by (a,b), weighed by f(a,b) and added to g(x,y).

BME1450 - 2002

linear systems and imaging fourier theory
Linear Systems and ImagingFourier Theory
  • Fourier Transform
  • Convolution Theorem
  • H is the transfer function of the system

BME1450 - 2002

linear systems and imaging effects of filtering
Linear Systems and Imaging Effects of filtering

Filter

Width

32 pix

In K space

Of

256x256

BME1450 - 2002

linear systems and imaging spectral components
Linear Systems and ImagingSpectral Components
  • Real part of the FFT of pixel Kx,Ky =3
  • Other pixels 0

BME1450 - 2002

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