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Digital image processing is the use of computer algorithms to
perform image processing on digital images. As a subcategory or field
of digital signal processing, digital image processing has many
advantages over analog image processing. It allows a much wider
range of algorithms to be applied to the input data and can avoid
problems such as the build-up of noise and signal distortion during
processing. Since images are defined over two dimensions (perhaps
more) digital image processing may be modeled in the form of
multidimensional systems.
Digital image processing allows the use of much more complex
algorithms, and hence, can offer both more sophisticated performance
at simple tasks, and the implementation of methods which would be
impossible by analog means.
In particular, digital image processing is the only practical technology
for:
- Classification
- Feature extraction
- Pattern recognition
- Projection
- Multi-scale signal analysis
Introduction
Signal processing is a discipline in electrical engineering and in mathematics that deals with analysis and processing of analog and digital signals , and deals with storing , filtering , and other operations on signals. These signals include transmission signals , sound or voice signals , image signals , and other signals e.t.c.
Out of all these signals , the field that deals with the type of signals for which the input is an image and the output is also an image is done in image processing. As it name suggests, it deals with the processing on images.
It can be further divided into analog image processing and digital image processing.
Analog image processing
Analog image processing is done on analog signals. It includes processing on two dimensional analog signals. In this type of processing, the images are manipulated by electrical means by varying the electrical signal. The common example include is the television image.
Digital image processing has dominated over analog image processing with the passage of time due its wider range of applications.
Digital image processing
The digital image processing deals with developing a digital system that performs operations on an digital image.
What is an Image
An image is nothing more than a two dimensional signal. It is defined by the mathematical function f(x,y) where x and y are the two co-ordinates horizontally and vertically.
The value of f(x,y) at any point is gives the pixel value at that point of an image.
How a digital image is formed
Since capturing an image from a camera is a physical process. The sunlight is used as a source of energy. A sensor array is used for the acquisition of the image. So when the sunlight falls upon the object, then the amount of light reflected by that object is sensed by the sensors, and a continuous voltage signal is generated by the amount of sensed data. In order to create a digital image , we need to convert this data into a digital form. This involves sampling and
This includes Zooming, blurring , sharpening , gray scale to color conversion, detecting edges and vice versa , Image retrieval and Image recognition.
Medical field
The common applications of DIP in the field of medical is
- Gamma ray imaging
- PET scan
- (^) X Ray Imaging
- Medical CT
- UV imaging
UV imaging
In the field of remote sensing , the area of the earth is scanned by a satellite or from a very high ground and then it is analyzed to obtain information about it. One particular application of digital image processing in the field of remote sensing is to detect infrastructure damages caused by an earthquake.
As it takes longer time to grasp damage, even if serious damages are focused on. Since the area effected by the earthquake is sometimes so wide , that it not possible to examine it with human eye in order to estimate damages. Even if it is , then it is very hectic and time consuming procedure. So a solution to this is found in digital image processing. An image of the effected area is captured from the above ground and then it is analyzed to detect the various types of damage done by the earthquake.
The key steps include in the analysis are
- The extraction of edges
- Analysis and enhancement of various types of edges
Transmission and encoding
The very first image that has been transmitted over the wire was from London to New York via a submarine cable. The picture that was sent is shown below
The picture that was sent took three hours to reach from one place to another.
Now just imagine , that today we are able to see live video feed , or live cctv footage from one continent to another with just a delay of seconds. It means that a lot of work has been done in this field too. This field doesnot only focus on transmission , but also on encoding. Many different formats have been developed for high or low bandwith to encode photos and then stream it over the internet or e.t.c.
Machine/Robot vision
Apart form the many challenges that a robot face today , one of the biggest challenge still is to increase the vision of the robot. Make robot able to see things , identify them , identify the hurdles e.t.c. Much work has been contributed by this field and a complete other field of computer vision has been introduced to work on it.
Hurdle detection
Hurdle detection is one of the common task that has been done through image processing, by identifying different type of objects in the image and then calculating the distance between robot and hurdles.
Line follower robot
Most of the robots today work by following the line and thus are called line follower robots. This help a robot to move on its path and perform some tasks. This has also been achieved through image processing.
