Multimedia Communication Image Processing CP 586 Peter

Multimedia Communication Image Processing CP 586 © Peter Lo 2003 1

Image Processing n Image processing is an enabling technology that allows users to manage information in the form of digital images. n n Scanners. High resolution screens. Optical storage media. Laser printers. CP 586 © Peter Lo 2003 2

Image Processing n Every process that can be carried out on conventional data should be extended to handle images. n n Filing (A 4 documents). TPS (cheques). CAD (engineering drawings). Medical imaging (X-rays). CP 586 © Peter Lo 2003 3

Display Resolution n The resolution of a computer display is the number of pixels that make up the height and width of the display presented by the computer monitor. A monitor with a resolution of 640 x 480 has 640 pixel along the horizontal axis and 480 pixels along the vertical access. The array would contain 307, 200 pixels. CP 586 © Peter Lo 2003 4

Computer Generated Colour n n HSL : Hue Saturation and lightness. Colour Palettes : Computers use palettes and CLUT to manage colour. The index values correlated to RGB values. As the palette size increases the file size also increases. Use Pal. Edit to experiment with palettes. CP 586 © Peter Lo 2003 5

Scanners n n Scanners are used to capture images and text for multimedia applications. Hand held : Used in post office to scan the bar code on bills. Drum : Scanning is limited to flat flexible documents. Flat Bed and Special purpose : Can be used to scan negatives and photographs. CP 586 © Peter Lo 2003 6

Selecting Graphics n n n Purpose : WWW based images need to have a small file size. High resolution is often a waste of time and resources. Quality : Poor colour depth or image quality can make a multimedia application look unprofessional and unappealing. Cost : Copyright and development costs come into play when developing images. CP 586 © Peter Lo 2003 7

DPI n n Abbreviation of dots per inch, which indicates the resolution of images. The more dots per inch, the higher the resolution. For example, if a printer had 800 DPI, it means it has 800 dots across and 800 dots down, so there are 640, 000 dots per square inch. CP 586 © Peter Lo 2003 8

OCR n n n OCR : Optical Character Recognition OCR can be used to create more relevant indexes by reading specific areas of the image to extract information such as date, customer name, delivery address. Using a "point and shoot" OCR application that can operate in batch mode, allows for highly automated scanning and indexing. CP 586 © Peter Lo 2003 9

Document Image Processing (DIP) n n n It is used to describe systems that convert paper documents into a digital form. This systems are capable of processing all types of documented information either graphical, full-text of combinations of both. The system is provided with indexing facilities to aid the searching and retrieval processes. A lot of research is being conducted into ways of indexing and storing images. Once stored, the imaging can then be utilised as inclusions within documents or faxed using a facsimile gateway application. CP 586 © Peter Lo 2003 10

Why use Document Image Processing? n n n Many computing companies have adopted computer technology that uses networking principles to distribute resources. This has led to wider dissemination of information. Some companies have taken this a step further, to deal electronically with suppliers sub-contractors and customers. CP 586 © Peter Lo 2003 11

Document Image Processing Applications n n n n Business related document processing. Insurance claims processing. High quality medical imaging. Decision support systems. Surgical planning. Pre-press publishing. Image databases. CP 586 © Peter Lo 2003 12

Decision Support System (DSS) n n n A collection of people, databases, procedures and devices used to support problem specific decision making. Can handle information from a variety of different sources. Provides report and presentation flexibility and has a graphical orientation. Multimedia modelling can be less expensive than experimenting with custom approaches or real systems. Can use a model base to aid decision making. CP 586 © Peter Lo 2003 13

Computer Assisted Design (CAD) n Reports and output from CAD applications can help engineers design better systems. CP 586 © Peter Lo 2003 14