July 1, 2021 Digital Image Processing, Lecturer
#2
1
Digital Image Processing
Digital Image Processing
Lecture #2
Lecture #2
Dr. Md. Hasanuzzaman
Professor
Department of Computer Science & Engineering
Dhaka University
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Digital Image Processing Lecture Notes: Introduction and Applications, Cheat Sheet of Digital Image Processing
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July 1, 2021 Digital Image Processing, Lecturer 1
Digital Image Processing
Digital Image Processing
Lecture #2 Lecture
Dr. Md. Hasanuzzaman
Professor
Department of Computer Science & Engineering
Dhaka University
July 1, 2021 Digital Image Processing, Lecturer 2
Contents
Contents
Introduction to Digital Image Processing
Applications of Digital Image Processing
Example Applications
Characteristics of Image Operation
July 1, 2021 Digital Image Processing, Lecturer 4
Definition of Image
Definition of Image
An image defined in the "real world" is considered
to be a function of two real variables, for example,
a ( x , y ) with a as the amplitude (e.g. brightness) of
the image at the real coordinate position ( x , y ).
A digital image a [ m , n ] described in a 2D discrete
space is derived from an analog image a ( x , y ) in a
2D continuous space through a sampling process
that is frequently referred to as digitization.
July 1, 2021 Digital Image Processing, Lecturer 5
Manipulation on Images
Manipulation on Images
Image Processing: image in -> image out
Image Analysis: image in -> measurements
out
Image Understanding: image in -> high-level
description out
July 1, 2021 Digital Image Processing, Lecturer 7
Example of Digitization
Example of Digitization
The 2D continuous image I ( x , y )
is divided into N rows and M
columns****.
The intersection of a row and a
column is termed a pixel****.
The value assigned to the
integer coordinates [ m , n ] with
{ m =0,1,2,..., M -1} and
{ n =0,1,2,..., N -1} is I [ m , n ].
depth ( z ), color (λ), time ( t )
July 1, 2021 Digital Image Processing, Lecturer 8
Quantization
Quantization
The process of representing the
amplitude of the 2D signal at a given
coordinate as an integer value with L
different gray levels is usually
referred to as amplitude quantization
or simply quantization
The value assigned to every pixel is
the average brightness in the pixel
rounded to the nearest integer value.
Image divided into
N = 16 rows and
M = 16 columns.
July 1, 2021 Digital Image Processing, Lecturer 10
Characteristics of Image
Characteristics of Image
Operations
Operations
Types of Image Operation
Types of neighborhoods
July 1, 2021 Digital Image Processing, Lecturer 11
Types of Image Operation (1)
Operation Characterization Generic
Complexi
ty/Pixel
- Point - the output value at a specific
coordinate is dependent only on the
input value at that same coordinate.
constant Image size = N x N ;
neighborhood size =
P x P. Note that the
complexity is
specified in
operations per pixel
- Local - the output value at a specific
coordinate is dependent on the input
values in the neighborhood of that
same coordinate.
P
2
- Global - the output value at a specific
coordinate is dependent on all the
values in the input image.
N
2
July 1, 2021 Digital Image Processing, Lecturer 13
Types of Neighborhoods
Types of Neighborhoods
Rectangular sampling: 4-connected 8-
connected
Hexagonal sampling: 6-connected
July 1, 2021 Digital Image Processing, Lecturer 14
Applications of Digital Image Applications of Digital Image
Processing
Processing
Remote sensing Via Satellites and other Spacecrafts
Image Transmission and Storage for Business Applications
Medical Image Processing
Radar
Robotics
Automatic Inspection of Industrial Parts
Person Identification for Security Measure, etc.
July 1, 2021 Digital Image Processing, Lecturer 16
Application: Face Detection
Application: Face Detection
July 1, 2021 Digital Image Processing, Lecturer 17