Imaging

1. BioMedical Image
Processing
Dr Haris Masood

2. 2
Information
 Lecturer: Dr. Haris Masood
 Consultation Hours: ??
 E-mail: haris.masood@wecuw.edu.pk

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Course Info
 Textbook
R. C. Gonzalez and R. E. Woods, DIGITAL IMAGE
PROCESSING, 2nd edition, Prentice Hall, 2002
 Reference
R. C. Gonzalez and R. E. Woods, DIGITAL IMAGE
PROCESSING with MATLAB , Prentice Hall,
Anil K. Jain, FUNDAMENTALS OF DIGITAL IMAGE
PROCESSING, Prentice Hall

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Assessment
Quizzes: 10%
Assignment/ Class Projects: 10%
Project: 10%
Mid: 30%
Final test: 50%

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DIP?
 Image processing is a subclass of signal
processing concerned specifically with
pictures.
Improve image quality for human perception
and/or computer interpretation

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DIP?
 The Field of DIP refers to processing of digital
images by means of Digital computers
 Two principal application
 Improvement of pictorial info. For human interpretation
 Processing of image data for
 Storage
 Transmission
 Representation for autonomous machine perception

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Historical Developments of DIP
 1920’s: Analog image transmission
Transatlantic picture transmission
London – New York
 1960’s: Space program
Invention of digital computer
hardware and software
Source data is very expensive
 1970’s: X-ray imaging (CT)
 Nowadays: Cheap computing
Lots of DIP applications

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Scope
 Computer vision aims to duplicate the effect of
human vision by electronically perceiving and
understanding an image.
 Not an easy task
 Three dimensional (3D) world,
 available visual sensors (e.g., TV cameras) usually give
two dimensional (2D) images
 this projection to a lower number of dimensions incurs an
enormous loss of information.

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Several fields deal with images
 Computer Graphics : the creation of images.
 Image Processing : the enhancement or
other manipulation of the image
the result of which is usually another images.
 Computer Vision: the analysis of image
contents

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Typical DIP system
 Digital Image Processing is processing of two-
dimensional data by a digital computer

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Digital Image
 Image
 Two-dimensional function f(x,y)
 x, y : spatial coordinates
 Value of f : intensity or gray level
 A set of pixels
 Pixel means
 pixel coordinates/location
 pixel value
 or both
 Both coordinates and value are discrete

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Example
e.g. 640 x 480 8-bit image

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Examples of Fields that use DIP
 Categorize by image sources
 Radiation from the Electromagnetic spectrum
Acoustic
 Ultrasonic
 Subsonic
Electronic (in the form of electron beams used in
electron microscopy)
Computer (synthetic images used for modeling and
visualization

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EM spectrum
 EM waves = a stream of mass-less (proton)
particles, each traveling in a wavelike pattern and
moving at the speed of light.
 Spectral bands are grouped by energy per photon
 Gamma rays, X-rays, Ultraviolet, Visible, Infrared,
Microwaves, Radio waves

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Gamma-Ray Imaging
 Nuclear medicine
Bone Scan
PET Scan (Positron emission
tomography) image
 Astronomical observation
Cygnus Loop
 Nuclear Reaction
shows an image of Gamma
radiation from a reactor valve

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X-ray Imaging
 Medical Diagnosis
chest X-ray (familiar)
aortic angiogram
head Computerized Axial
Tomography (CAT)
 Astronomy
Cygnus Loop
 Industrial Applications
Circuit board

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UV Band Imaging
 Lithography
 Industrial inspection
 Microscopy (fluorescence)
Normal corn
Smut corn
 Lasers
Biological imaging
Astronomical observations
Cygnus Loop

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Visible& infrared Imaging
 Medical microscopy
Anticancer medicine(250x)
Cholesterol (40x)
 Industrial applications
Microprocessor (60x)
Nickel oxide film (600x)
Surface of audio CD (1750x)
Organic superconductor(450x)

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Imaging in Microwave Band
 Imaging radar : the only way
to explore inaccessible
regions of the Earth’s surface
Radar image of mountains in
southeast Tibet
Note the clarity and detail of the
image, unencumbered by
clouds or other atmospheric
conditions that normally
interfere with images in the
visual band

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Imaging in Radio Band
 Medicine
Magnetic resonance
image (MRI) : 2D
picture of a section of
the patient (any plane)
 knee
 spine
 Astronomy

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Acoustic Imaging
 Geological applications use
sound in the low end of the
sound spectrum (hundred of
Hz)
Mineral and oil exploration
 Cross-sectional image of a
seismic model

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Ultrasound images
 Transmit ultrasound (1 to
5MHz)
 Sound pulses are
reflected from tissues
 Compute the distance
using the speed
 Display the distances and
intensities of the echoes

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3 types of computerized
process
 Low-level : input, output are images
 Primitive operations such as image preprocessing to reduce
noise, contrast enhancement, and image sharpening
 Mid-level : inputs may be images, outputs are attributes
extracted from those images
 Segmentation
 Description of objects
 Classification of individual objects
 High-level :
 Image analysis
 Image Understanding

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Computational Complexity of DIP
 HDTV quality video
 Resolution : 1024 x 768
 786,432 pixels
 Refresh rate : 30 pictures/s
 Compute average gray level of each picture
 786,432 x 30 = about 23 million additions/s
 Digital video processing had not been possible for a
long time

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Components of DIP System

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Sampling and Quantization

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Sampling and Quantization
 Sampling
Digitization in Spatial
Domain

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Sampling and Quantization
 Quantization
Digitization of pixel levels

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Image Enhancement
 To bring out detail, which is
obscured, or simply to
highlight certain features of
interest in an image.
 To accentuate certain image
features for subsequent
analysis or for image display
Subjective process
g(x,y) = 255 – f(x,y)

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Image Enhancement

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Image Restoration
 To remove or minimize
known/unknown
degradations in image

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Image Restoration

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Color Image Processing

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Image Compression
 Objective
To reduce the amount
of data to represent
images
From the bit stream,
the approximate copy
of
the original image can
be reproduced

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Image Compression
 JPEG compression
1000 x 1000 RGB picture = 3 MB
16 MB memory card can store only 5 pictures
With JPEG, the same card can store more than 80
pictures

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Image Compression
 Video compression
 HDTV quality video
 1024 x 768 x 3 x 30 x 8 = 566 Mbits/s (Mbps)
 Video compression standards
 MPEG-1: Video-CD, 1-2 Mbps
 MPEG-2: HDTV and DVD, 2-15 Mbps
 H.263: Low bit-rate applications,
10-2048 Kbps
 MPEG-4: similar to H.263
 H.264/AVC : new video coding standard

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Image Compression
 Mobile video transmission
Compression ratio = 158 : 1

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Image Segmentation
 Edge detection

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Image Segmentation
Original Segmented

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Image Segmentation
 Image Segmented by
local Thresholding

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Image Description
 Objective
interpret or describe
the meaning
contained in image
 Output is not image

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Reading Assignment
 Chapter 1

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Sampling and Quantization
 Computers cannot process
parameters/functions that vary in a continuum
 We have to discretize:
x, y => xi , yj where (i = 0; : : : ;N 1; j = 0; : : : ;M ¡
1): Sampling
f(x, y) =>F(xi , yj)
Quantization

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Sampling
 Obtain sampling by utilizing f (x, y) x comb(x, y)

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Sampling and Quantization

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Sampling and Quantization
 Sampling
Digitization in Spatial
Domain

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Objectives ( C_1)
 To define the scope of DIP
 To give historical perspective of the origins of this
field
 To give an Idea of the stat of the art in DIP by
examining some of the principal areas in which this
field is applied
 To give an overview of the components contained in
a typical DIP system