# Digital Image Processing

AI and Robotics

Nov 6, 2013 (4 years and 6 months ago)

144 views

Digital Image Processing

Hongtao Lu

Dept. of Computer Science

Sept. 2006

Text Book

DIGITAL IMAGE PROCESSING

Kenneth R. Castleman

/ Prentice Hall

1997

Reference Books

Digital Image Processing (Second Edition)

Rafael C. Gonzalez and Richard E. Woods

2002

2001

Chapter 1 Images and Digital
Processing

1.1 Introduction

What is an image?

An image may be defined as a two
-
dimensional
function,
f(x,y)
, where
x

and
y

are spatial (plane)
coordinates, and the amplitude of f at any pair
of Coordinate
(x,y)

is called the
intensity

or
gray level

of the image at that point.

What is a digital image?

When
x, y

and the amplitude
f(x,y)

of an image
are all finite, discrete quantities, an image is
called a digital image.

A digital image is composed of a finite number
of elements, each such element is called a
picture element

or a
pixel
.

A digital image is a numerical representation of
an object

What is Digital Image Processing?

Processing image by means of a digital
computer

Digital image processing is a process that
subjecting a numerical representation of an
object to a series of operations in order to
obtain a desired result.

1.2 The elements of digital image
processing

Digitization

Process of converting a physical image to a digital
image

Spatial sampling (Rectangular sampling)

Physical

Image

Quantization: representing the continuous
intensity value with finite number of integers.

A typical image
-
processing
system

Image
Digitizer

Input
Image
Storage

Computer

Output
Image
Storage

Console

Image
Recorder

Program
Library

1.2.1 The Terminology of DIP

Physical images

Distributions of matter or energy (may be
visible or nonvisible)

Multi
-
spectral images
----
those having more
than one local properties at each location. Color
image

Abstract images

Continuous or discrete functions

Types of images

Objects

Images

Visible images

Pictures

Photographs

Drawings

Paintings

Optical images

Mathematical
functions

Continuous

Discrete

Non
-
visible
physical images

Computer Graphics

Processing and display of images of things that
exist conceptually or as mathematical
descriptions.

Generation of a image, given a model that
describes the object, its illumination, and the
geometry of an imaginary camera.

Computer vision

Developing systems that can interpret the
content of natural scenes.

Chapter 2 Digitizing Images

2.1 Introduction

The Elements of a digitizer

Sampling aperture

Mechanism for scanning the image

Light sensor

Quantizer

Output storage medium

2.2 Characteristics of an image digitizer

Pixel size

Image size

Local property measured

Linearity

Noise

2.3 Types of image digitizer

Scan
-
in and Scan
-
out Digitizing

2.4 Image
-
Digitizing Components

2.4.1 Light Sources

Incandescent Bulbs

Lasers

Phosphors

LEDs

2.4.2 Light Sensors

Photoemissive Devices (

)

Silicon Sensors

Photodiodes(

)

Phototransistor(

)

2.4.3 Scanning Mechanisms

Mechanical scanning devices

Electron beam scanning

Electrostatic deflection (

)

Magnetic Deflection (

)

Beam focus (

)

Chapter 3 Digital Image Display

3.1 Introduction

3.1.1 Image quality

3.2 Display Characteristics

Displayed image size

Photometric resolution (

Gray
-
scale linearity

Display calibration

Low frequency response

Pixel polarity

Pixel interaction

The Gaussian display spot

Display spot interaction

)
(
2
2
)
,
(
y
x
e
y
x
p

Examples of Fields that use DIP
(supplement)

Images categorized by electromagnetic (EM)
energy spectrum

5
10
4
10
3
10
2
10
1
10
0
10
1
10

2
10

3
10

4
10

5
10

6
10

7
10

Energy of one photon

Gamma
rays

X
-
rays

Ultra
-
violet

Visible

Infrared

Microwaves

waves

Gamma
-
Ray Imaging

Nuclear medicine

Astronomical observations

Positron emission
tomography PET

A PET image

X
-
ray Imaging

X
-
ray medical diagnostics

Angiography (contrast
-
enhancement

Computerized axial tomography

Astronomy

Applications (e.g. X
-
ray inspection)

X
-
ray imaging

An angiogram image

X
-
ray imaging

An X
-
ray image of circuit board

Imaging in the Ultraviolet band

Fluorescence microscopy

Lithography

Industrial inspection

Astronomical observations

A Fluorescence microscope

Imaging in the visible and
infrared bands

Light microscope

Taxol

Cholesterol

Surface of audio CD

Remote sensing (multispectral
imaging)

Weather observation and
prediction

Automated visual inspection in manufacture
industrial

Pattern recognition

Imaging in the microwave band

Medicine (MRI: Magnetic resonance imaging)

Astronomy

MRI Knee

Examples of other imaging
modalities

Imaging using “Sound”

Geological exploration (Using sound in the low
end of the sound spectrum (hundreds of Hertz)

Medicine (ultrasound imaging, 1
-
5 MHz)

Electron microscope

Synthetic image (generated by
computer)

Fractal

3
-
D modeling

Fundamental steps in DIP

Color image
processing

Wavelets and
multiresolution

Compression

Morphological
processing

Image
restoration

Image
enhancement

Image
acquisition

Segmentation

Representation
& description

Object
recognition

Problem domain

Output image attributes

Output images

Knowledge base

Components of an image
processing system

Image
displays

Computer

Mass
storage

Hardcopy

Specialized
image
processing
hardware

Image
processing
software

Image
sensors

Problem
domain

Network

Elements of visual perception

Perceived brightness is not a simple
function of intensity

An example of simultaneous contrast

Some well
-
known optical illusion