WMES3103 : INFORMATION RETRIEVAL

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WMES3103 INFORMATION RETRIEVAL

• TEXT AND MULTIMEDIA LANGUAGES AND PROPERTIES

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INTRODUCTION

• Text - main form of communicating data and
  information
• Text also supplemented with multimedia elements -
  to make the contents of an IRS more attractive
  and interactive
• Website with a combination ot text and multimedia
  will be visited by many as compared to one which
  is text-based only
• IRS - text and multimedia is depicted via special
  languages.

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Metadata

• New concept on information metadata
• Information about data arrangement, data domain
  and relationship between the two
• Data about data
• 2 types descriptive and semantic

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• descriptive Metadata metadata which explain
  about document or one unit of information
• Commonly used Metadata
• Authors
• Date of publication
• Source of publication
• Length of document
• Type of document

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Metadata

• semantic Metadata resembles subject that can be
  obtain from the contents of the document
  subjects heading
• Keywords
• LC Code

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TEXT

• With computers, we need to code text into binary
  digits
• First coding schemes EBCDIC and ASCII 7 bits
  to code each symbol
• Then, ASCII changed to 8 bits to accommodate
  other languages, accents and diacritical marks
• Oriental languages Unicode 16 bits

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TEXT

• Formats
• No one single format for a text document
• Good IRS system should be able to retrieve
  information from any format
• Initially, IRS will convert a document to an
  internal format but this had a lot of
  disadvantages
• Now, many new format has been developed for
  document interchange

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TEXT

• RTF Rich Text Format for word processing
• PDF Portable Document Format for displaying and
  printing documents
• Postscript powerful programming language for
  drawing
• MIMT Multipurpose Internet Mail Exchange to
  encode e-mail
• Files are compressed Compress (Unix), ARJ
  (PCs), ZIP
• Convert binary files to ASCII text
  uuencode/uudecode, binhex

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MARKUP LANGUAGES

• Markup extra textual syntax that can be used to
  describe formatting actions, structure
  information, text semantics, attributes, etc.
• Formal markup languages are more structured
• Marks tags - initial and ending tag surrounding
  the marked text
• Standard metalanguage SGML
• New metalanguange for Web XML (eXtensible
  Markup Language) subset of SGML
• Most popular markup language used for the Web
  HTML (HyperText Markup Language)

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MULTIMEDIA

• Applications that handle different types of
  digital data originating from distinct types of
  media
• Text, sound, images, video
• Digital data distinct and different in volume,
  format, and processing requirements
• Different types of formats necessary for storing
  each type of media

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MULTIMEDIA

• Different formats used commonly on the Web and in
  digital libraries
• Images
• Audio
• Moving Images
• Textual Images
• Graphics and Virtual Reality

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IMAGES

• XBM, BMP, PCX direct representation of a
  bit-mapped (or pixel-based)
• GIF (Graphic Interchange Format) includes
  compression and good for black or white or with
  small number of clours or gray levels (256)
• JPEG (Joint Photographic Experts Group)
  includes compression
• TIFF (Tagged Image File Format) used to
  exchange different documents between different
  applications and different computer platforms
• TGA (Television Targa image file) associated
  with video game boards
• Various other image formats

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AUDIO

• Must be digitized before storage
• AU, MIDI (standard format to interchange music
  between electronic instruments and computers),
  WAVE for small pieces of digital audio
• Audio libraries RealAudio or CD formats
• Animation or moving pictures
• MPEG (Moving Pictures Expert Group) related to
  JPEG
• Others AVI, FLI, QuickTime

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TEXTUAL IMAGES

• Images that contain mainly typed or typeset text
• Obtained by scanning the documents
• For archival purposes
• Saved as images but with further compression
• Textual and non-textual stored and compressed
  separately and when neded can be combined and
  displayed together

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GRAPHICS AND VIRTUAL REALITY

• 3-dimensional graphics found on Web
• CGM (Computer Graphics Metafile) standard
• Metafile collection of elements
• CGM standard specifies which elements are allowed
  to occur in which positions in a metafile
• VRML (Virtual Reality Modeling Language) file
  format for describing interactive 3D objects and
  worlds - universal interchange format for 3D
  graphics and multimedia - can be used for various
  applications

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MULTIMEDIA DOCUMENTS MARKUP

• HyTime Hyper/Time-based Structuring Language
  standard defined for multimedia documents markup
• SGML architecture which specifies the generic
  hypermedia structure of documents