Dip Class1

“One picture is worth more than ten thousand words” Anonymous

Presented by- PREETHI SJ

-Preethi S.J., PESIT

Title and author

Publication information

Edition Publisher Year

Fundamentals of digital image processing Anil K Jain

---- Pearson

Education, PHI

2005

Digital image processing

Rafael C Gonzalez and Richard E Woods

second

Wesley/Pearson Education

2005

Digital image processing

William. K. Pratt

second

Wiley Interscience

1991


Chapter 1

Digital Image Fundamentals

Chapter 1

Digital Image Fundamentals

Text 2: Digital image processing

Rafael C Gonzalez and Richard E Woods

Chapter 1,

1.1,1.4,1.5; Chapter 2,

2.1,2.3 to 2.6

*What is Digital Image Processing?

*Fundamental steps in digital image processing.

*Components of an image processing system.

*Elements of visual perception.

*Image sensing and acquisition.

*Image sampling and quantization.

*Some basic relationships between pixels.

*Linear and Nonlinear operations.


What is Digital Image Processing?

Digital Image: — a two-dimensional function f(x,y) , x and y are spatial coordinates. The amplitude of f is called intensity or gray level at the point (x, y)

Pixel(Picture elements, image elements, pels):

1 pixel

The smallest square element

of a digital image,

representing a single color or

level of brightness


Act of converting an image

Captured form to another form

IMAGE PROCESSING


“Vision is the most advanced of our senses, so it is not surprising that images play most important role in human

perception” The continuum from image processing to computer vision can

be broken up into low-, mid- and high-level processes

Low Level Process

Input: Image Output: Image

Examples: Noise removal, image sharpening

Mid Level Process

Input: Image Output: Attributes

Examples: Object recognition, segmentation(partitioning image into regions or objects)

High Level Process

Input: Attributes Output: Understanding

Examples: Scene understanding, autonomous navigation

Input and output are

images

Input is image & outputs

are attributes extracted

form image(edge,contour

etc..)

Involves “making sense “

Like cognitive functions

associated with human

vision


Early 1920s: One of the first applications of digital imaging was in the news-paper industry

The Bartlane cable picture transmission service (3 hr transmission)

Images were transferred by submarine cable between London and New York

Pictures were coded for cable transfer and reconstructed at the receiving end on a telegraph printer


Mid to late 1920s: Improvements to the Bartlane system resulted in higher quality images

New reproduction processes based on photographic techniques

(made from tapes)

Increased number of tones in reproduced images

Improved digital image

Early 15 tone digital image


1960s: Improvements in computing technology and the onset of the space race led to a surge of work in digital image processing

1964: Computers used to improve the quality of images of the moon taken by the Ranger 7 probe

Such techniques were used in other space missions including the Apollo landings

A picture of the moon taken by the Ranger 7 probe minutes

before landing


1970s: Digital image processing begins to be used in medical applications

1979: Sir Godfrey N. Hounsfield & Prof. Allan M. Cormack share the Nobel Prize in medicine for the invention of tomography, the technology behind Computerised Axial Tomography (CAT) scans

Typical head slice CAT image


1980s - Today: The use of digital image processing techniques has exploded and they are now used for all kinds of tasks in all kinds of areas

Image enhancement/restoration

Artistic effects

Medical visualisation

Industrial inspection

Law enforcement

Human computer interfaces


Light and electro magnetic Spectrum


Examples of fields that use Digital Image Processing

“Unlike humans, who are limited to the visual band of the electromagnetic spectrum, imaging machines cover almost the

entire EM spectrum, ranging from gamma to radio waves”


Gamma-Ray imaging

Inject a patient with a radio active isotope that emits Gamma rays as it decays. Images are produced from the emissions collected by gamma ray detectors.


X-Ray imaging

An x-ray source is turned on and x-rays are radiated through the body part of interest and onto a film cassette positioned under or behind the body part. A special phosphor coating inside the cassette glows and exposes the film. The resulting film is then developed much like a regular photograph.

As the x-rays pass through, the Bone is very dense and absorbs or attenuates a great deal of the x-rays. The soft tissue around the bones is much less dense and attenuates or absorbs far less x-ray energy. It is these differences in absorption and the corresponding varying exposure level of the film that creates the images which can clearly show broken bones, clogged blood vessels, cancerous tissues and other abnormalities.


Imaging in the ultra violet band

Ultraviolet light is used in fluorescence microscopy (viewing objects and areas of objects that cannot be seen with the naked eye) Ultraviolet light itself is not visible, but when a photon of ultraviolet radiation collides with an electron in an atom of a fluorescence material, it elevates electron to higher energy level, and when the electron relaxes to a lower level it emits light (visible red).


These images are Part of the night time Lights of world data set, Which provides a global Inventory of human Settlements.


The area in which the imaging system detected the plate

Results of automated reading of the plate content by the system


Imaging in the Microwave Band

Application: Radar imaging An imaging radar works like a flash camera. It provides its own illumination (microwave pulses) to illuminate an area on the ground and take a snapshot image. Instead of a camera lens, a radar uses an antenna and digital computer processing to record its images. In a radar image one can see only the microwave energy that was reflected back toward the radar antenna. Unique feature of imaging radar is its ability to collect data over any region, at any time, regardless of weather (radar can penetrate coluds) or ambient lighting conditions.


Imaging in the Radio Band

Application: in medicine (Magnetic resonance imaging MRI) and astronomy MRI technique places a patient in a powerful magnet and passes radio waves through his or her body in short pulses. These pulse causes a pulse of radio waves to be emitted by the patient’s tissues. The location from which these signals originate and their strength are determined by a computer, which produces 2D picture of a section of the patient.


Ultrasound Imaging Application: in medicine 1. The ultrasound system transmits high frequency (1 to 5

Mhz) sound pulses into body

2. The sound waves travel into the body and hit a boundary(tissue, bones) . Some of the sound waves are reflected back to the probe, while some travel further until they reach another boundary & get reflected.

3. Reflected waves are picked up by probe

4. Machine calculates and displays the distances and intensities of the echoes on the screen forming a two dimensional image.


Fractal Images

Examples of computer generated images- iterative reproduction of a basic pattern according to some mathematical rules.


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