Digital Image Processing

chemistoddAI and Robotics

Nov 6, 2013 (3 years and 7 months ago)

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Digital Image Processing

Hongtao Lu

Dept. of Computer Science

Sept. 2006

Text Book


DIGITAL IMAGE PROCESSING


Kenneth R. Castleman


清华大学出版社

/ Prentice Hall


1997

Reference Books


Digital Image Processing (Second Edition)


Rafael C. Gonzalez and Richard E. Woods


电子工业出版社

原版影印


2002



数字图像处理学,阮秋琦

编著,电子工
业出版社,
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 (
光电发射器件
)


Silicon Sensors


Photodiodes(
光敏二极管
)


Phototransistor(
光敏三极管
)


2.4.3 Scanning Mechanisms


Mechanical scanning devices


Electron beam scanning


Electrostatic deflection (
静电偏转
)


Magnetic Deflection (
磁偏转
)


Beam focus (
电子束聚焦
)

Chapter 3 Digital Image Display


3.1 Introduction


3.1.1 Image quality


3.2 Display Characteristics


Displayed image size


Photometric resolution (
光度分辨率)


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

Radio
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
radiography)


Computerized axial tomography


Astronomy


Applications (e.g. X
-
ray inspection)

X
-
ray imaging




An angiogram image

Head CT

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


Radar


Radar image of Southeast Tibet


Imaging in the Radio 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