Two major applications. While the first one is for human interpretation and the second one for machine interpretation.
Introduction to Medical Imaging
Chapter 1: Introduction
13 November 2016 1
Hossain Md Shakhawat
Department of Information Processing
Tokyo Institute of Technology
Digital Image Processing -3rd Edition by Rafael C.
Gonzalez, Richard E. Woods
One picture is worth more than ten thousand words
Objectives of the chapter
Introduction to Digital image processing (DIP)
Define the scope of DIP
Introduce the application areas
Introduce the principle approaches of DIP
Components of image processing
Provide directions to the book
What is Image ?
Mathematically, Image is a two dimensional function f(x,y) where the x and
y are spatial co-ordinates and the amplitude of function “ f ” at any pair of
co-ordinates (x,y) is called the intensity of the image at that point.
Analog Image: when x, y and the amplitude
values of f are continuous quantities
Digital Image: when x, y and the amplitude
values of f are all finite and discrete
Digital image is composed of finite number of elements called pixels,
each of which has a particular location and intensity value.
Digital Image Processing
DIP is the processing of digital image in a digital manner meaning that
is using a digital device like digital computer.
Two major application areas:
1. Improvement of pictorial information for human interpretation.
2. Processing of image data for storage, transmission and
representation for autonomous machine perception
Digital Image Digital Computer
Level of Image Processing
Image to image transformation
Image to attribute transformation
Attribute to image transformation
Input Process Output
Post ProcessingRevealed Underplayed
Advantages of Digital
Origin and Evolution of DIP
DIP technology evolved with the advancement in digital computers
1920 -> Bartline cable system reduced the time for transmission from week to hours
1921 -> pictures were produced from a coded tape by telegraph printers
1922 -> Improvements in the reproduction system increased visual quality
1929 -> Number of gray levels increased to 15 from 5
1940 -> Invention of modern digital computer
1940 to 1960 -> Development of transistors, IC, programming language, operating
system and microprocessor made the computer efficient enough for DIP.
1960 -> First use of computer to correct images of moon
1970 -> Early applications in medical imaging
1980 to till date -> Enabled the modality of image analysis and computer vision
Pictures were sent using submarine cable for news
Unlike the humans who are limited to visible band of electromagnetic
spectrum (EM), the imaging machines cover almost the entire EM
spectrum from gamma to radio waves.
Thus DIP encompasses a wide and diverse fields of applications that
human are not accustomed to.
One efficient way is to analyze the fields based on the sources of image:
Gamma ray imaging
Imaging in visible and infrared bands
Imaging in microwave band
Imaging in radio band
Based on gamma rays. Includes nuclear medicine(i.e. bone pathology, PET) and
1. Radioactive isotope is injected into body
2. Isotope emits gamma rays as it decays
3. Images are produced from the emissions,
collected by gamma ray detector.
Examples: Bone scanning, Positron emission
1. Bone Scan 2. PET Image
• A star in the constellation area of Cygnus exploded
thousands years ago. This generated the superheated
gas cloud called Cygnus loop cloud, that glows in a
spectacular array of colors.
• Unlike the above two (1 & 2) this image (3) was obtained
using the natural radiation of the object.
3. Cygnus loop of gas cloud
• Imaging with X-rays:
1. An X-ray beam produced by X-ray tube passes through the
2. On it’s way through the body, parts of the energy of the X-ray
beam are absorbed, called attenuation of the X-ray beam.
3. On the opposite side of body, detectors or a film capture the
attenuated X-rays, resulting in a clinical 2D image.
4. In Computed Tomography, the tube and the detector are both
rotating around the body so that multiple images can be
acquired for 3D visualization.
• Examples: Medical (X-ray radiography, computed tomography
(CT), mammography, angiography and fluoroscopy) and
1. Radiography of chest
2. CT scan of head
• The ultraviolet light is not visible but it offers
a wide area of applications: lithography,
industrial inspection, fluorescence
microscopy, lasers, biological imaging and
1. Smut Corn Detection
Left: Normal Corn Right: Smut Corn
2. Mouse Brain Tissue Section
[ Source: http://www.microscopyu.com/galleries/fluorescence/index.html ]
• Infrared imaging has the unique
capability to observe sources of faint
sources of visible-near infrared
emissions of the earth surface including
cities, villages, gas flames and fires.
• Offers extreme level remote sensing and
also in medical science
1. Satellite image of hurricane Katrina
• Imaging in the visible band
• Radar imaging provides its own illumination (microwave pulses) to illuminate the
subject and capture the image.
• Instead of using lens it uses an antenna and digital computer to record or
capture the image.
• Major application: radar imaging
• Radar imaging can collect data of any
region without regarding the
weather or ambient light conditions.
• It can penetrate clouds.
1. Radar image of Tibet mountain
• Like the other end (gamma ray) of spectrum
major applications of radio band are also
medicine and astronomy. Ex: MRI (Magnetic
resonance imaging ).
• MRI is Safer than CT
1. Places the patient in a powerful magnet and
passes radio waves through the body in
2. Each pulse causes a responding pulse of
radio waves to be emitted by the body (H2).
3. Location and strength of these signals is
captured to form the 3D image
1. TEM Image of Polio Virus
2. Ultrasound image of Unborn
3. SEM Image of Polen Grains
Components of DIP System
Computer Mass Storage