Image Processing - Peter Lo

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6 Νοε 2013 (πριν από 4 χρόνια και 1 μήνα)

83 εμφανίσεις

1

CP586 © Peter Lo 2003

Multimedia Communication

Image Processing

CP586 © Peter Lo 2003

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Image Processing


Image processing is an enabling technology that
allows users to manage information in the form of
digital images.


Scanners.


High resolution screens.


Optical storage media.


Laser printers.

CP586 © Peter Lo 2003

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Image Processing


Every process that can be carried out on
conventional data should be extended to handle
images.


Filing (A4 documents).


TPS (cheques).


CAD (engineering drawings).


Medical imaging (X
-
rays).

CP586 © Peter Lo 2003

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Display Resolution


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.

CP586 © Peter Lo 2003

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Computer Generated Colour


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 PalEdit to experiment with palettes.

CP586 © Peter Lo 2003

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Scanners


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.


CP586 © Peter Lo 2003

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Selecting Graphics


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.

CP586 © Peter Lo 2003

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DPI


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.

CP586 © Peter Lo 2003

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OCR


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.


CP586 © Peter Lo 2003

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Document Image Processing (DIP)


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.

CP586 © Peter Lo 2003

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Why use Document Image Processing?


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.

CP586 © Peter Lo 2003

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Document Image Processing
Applications


Business related document processing.


Insurance claims processing.


High quality medical imaging.


Decision support systems.


Surgical planning.


Pre
-
press publishing.


Image databases.

CP586 © Peter Lo 2003

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Decision Support System (DSS)


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.

CP586 © Peter Lo 2003

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Computer Assisted Design (CAD)


Reports and output from CAD applications can
help engineers design better systems.