The field of digital image processing refers to processing digital images by means of digital computer. Digital image is composed of a finite number of elements, each of which has a particular location and value. These elements are called picture elements, image elements, pels and pixels. Pixel is the term used most widely to denote the elements of digital image.
What is 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 of the image at that point.
What is gray level ?
The term gray level is used often to refer to the intensity of monochrome images. Color images are formed by a combination of individual 2-D images
APPLICATIONS OF DIGITAL IMAGE PROCESSING
- Remote sensing via satellites and other spacecrafts
- Image transmission and storage for business applications
- Medical processing
- RADAR (Radio Detection and Ranging)
- SONAR(Sound Navigation and Ranging)
- Acoustic image processing
- Robotics and automated inspection of industrial parts.
- Recognition and analysis of objects contained in images obtained from deep space-probe missions.
- Processing of chest X- rays
- Teleconferencing
Components of Image processing System:
Image Sensors:with reference to sensing, two elements are required to acquire digital image. The first is a physical device that is sensitive to the energy radiated by the object we wish to image and second is specialized image processing hardware
Specialize image processing hardware:It consists of the digitizer just mentioned, plus hardware that performs other primitive operations such as an arithmetic logic unit, which performs arithmetic such addition and subtraction and logical operations in parallel on images.
Computer:It is a general purpose computer and can range from a PC to a supercomputer depending on the application. In dedicated applications, sometimes specially designed computer are used to achieve a required level of performance
Software:It consists of specialized modules that perform specific tasks a well designed package also includes capability for the user to write code, as a minimum, utilizes the specialized module. More sophisticated software packages allow the integration of these modules
Mass storage:This capability is a must in image processing applications. An image of size 1024 x1024 pixels, in which the intensity of each pixel is an 8- bit quantity requires one Megabytes of storage space if the image is not compressed
Image display:Image displays in use today are mainly color TV monitors. These monitors are driven by the outputs of image and graphics displays cards that are an integral part of computer system
Hardcopy devices:The devices for recording image includes laser printers, film cameras, heat sensitive devices inkjet units and digital units such as optical and CD ROM disk. Films provide the highest possible resolution, but paper is the obvious medium of choice for written applications
Image acquisition:It could be as simple as being given an image that is already in digital form. Generally the image acquisition stage involves processing such scaling.
Image Enhancement:It is among the simplest and most appealing areas of digital image processing. The idea behind this is to bring out details that are obscured or simply to highlight certain features of interest in image. Image enhancement is a very subjective area of image processing.
Image Restoration:It deals with improving the appearance of an image. It is an objective approach, in the sense that restoration techniques tend to be based on mathematical or probabilistic models of image processing. Enhancement, on the other hand is based on human subjective preferences regarding what constitutes a “good” enhancement result
Color image processing:It is an area that is been gaining importance because of the use of digital images over the internet. Color image processing deals with basically color models and their implementation in image processing applications
What is SAMPLING AND QUANTIZATION ?
Digitalizing the coordinate values is called sampling. Digitalizing the amplitude values is called quantization
Spatial Correlation
Correlation is the process of moving a filter mask over the image and computing the sum of products at each location