CSE 419
Digital Image Processing
Reference Book
Digital Image Processing (3rd Edition)
Gonzalez and Woods
What is an Image/Digital Image?
What is an Image/Digital Image?
Let us consider this gray scale image
What is an Image/Digital Image?
A gray scale image
y
f(x, y)
x
2 attributes:
◦ A location (x, y): picture element, pixel,
◦ A value f(x, y) at pixel (x, y): gray scale value
f(x, y) is known as the intensity of the image at (x,y)
What is an Image/Digital Image?
A gray scale image
y
f(x, y)
f(x, y) can take any value from 0.0 (black) to 1.0 (white)
What is an Image/Digital Image?
A gray scale image
y
f(x, y)
x
Digital image means
pixels locations (x, y) are discrete
gray level values f(x,y) are also discrete
What is an Image/Digital
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 coordinates (x,
y) is called the intensity or gray level of the
image at that point.
When x, y, and the amplitude values of f are
all finite, discrete quantities, we call the
image a digital image.
The field of digital image processing refers to
processing digital images by means of a
digital computer.
Digital Image Processing
Processing of digital images using digital devices
(computers)
DIP
Why we need DIP
• Core area
• Application area
Why we need DIP
Core area
• Image enhancement
• Image de-noising
• Image segmentation
• Image & video retrieval
• Image compression
Why we need DIP
Application area
• Security and surveillance
o Biometric application: face, iris, finger print, palm
print recognition . .
• Medical imaging
Automatic scanning and detection: X-ray, CT, MRI,
PET, angiogram, ECG, echo, endoscopy, ….
Why we need DIP
Application area
• Document Classification
character recognition
• Object and shape recognition
• Intelligent transport system
• Environmental monitoring
• and so on, . . .
Fundamental Steps in DIP
Fundamental Steps in DIP
1. Image Acquisition
This is the first step or process of the fundamental steps of digital image
processing. Image acquisition could be as simple as being given an image
that is already in digital form. Generally, the image acquisition stage involves
preprocessing, such as scaling etc.
2. Image Enhancement
Image enhancement is among the simplest and most appealing areas of
digital image processing. Basically, the idea behind enhancement techniques
is to bring out detail that is obscured, or simply to highlight certain
features of interest in an image. Such as, changing brightness & contrast
etc.
3. Image Restoration
Image Restoration is the operation of taking a corrupt/noisy image and
estimating the clean, original image. Corruption may come in many forms
such as motion blur, noise and camera mis-focus. ... More
advanced image processing techniques must be applied to recover the
object.
Fundamental Steps in DIP
4. Color Image Processing
Color image processing is an area that has been gaining its
importance because of the significant increase in the use of
digital images over the Internet. This may include color
modeling and processing in a digital domain etc.
5. Wavelets and Multiresolution Processing
Wavelets are the foundation for representing images in
various degrees of resolution. Images subdivision successively
into smaller regions for data compression and for pyramidal
representation.
6. Compression
Compression deals with techniques for reducing the storage
required to save an image or the bandwidth to transmit it.
Particularly in the uses of internet it is very much necessary
to compress data.
Fundamental Steps in DIP
7. Morphological Processing
Morphological processing deals with tools for extracting image
components that are useful in the representation and description of shape.
8. Segmentation
Segmentation procedures partition an image into its constituent parts or
objects. In general, autonomous segmentation is one of the most difficult
tasks in digital image processing. A rugged segmentation procedure brings
the process a long way toward successful solution of imaging problems
that require objects to be identified individually.
9. Representation and Description
Representation and description almost always follow the output of a
segmentation stage, which usually is raw pixel data, constituting either the
boundary of a region or all the points in the region itself. Choosing a
representation is only part of the solution for transforming raw data into a
form suitable for subsequent computer processing. Description deals with
extracting attributes that result in some quantitative information of
interest or are basic for differentiating one class of objects from another.
Fundamental Steps in DIP
10. Object recognition
Recognition is the process that assigns a label, such as,
“vehicle” to an object based on its descriptors.
11. Knowledge Base:
Knowledge may be as simple as detailing regions of an
image where the information of interest is known to
be located, thus limiting the search that has to be
conducted in seeking that information. The knowledge
base also can be quite complex, such as an
interrelated list of all major possible defects in a
materials inspection problem or an image database
containing high-resolution satellite images of a region
in connection with change-detection applications.
Components of an Image Processing System
Image Enhancement
Image Enhancement
Image De-noising
Noisy image Noise reduction by median filter
Image Compression
0 1
2 3 4
5 6 7
Image Compression
Image Reconstruction from fewer bits
Image Compression
Image Reconstruction from fewer bits
Image Segmentation
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