alternative retrieval techniques l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Alternative Retrieval Techniques PowerPoint Presentation
Download Presentation
Alternative Retrieval Techniques

Loading in 2 Seconds...

play fullscreen
1 / 20

Alternative Retrieval Techniques - PowerPoint PPT Presentation


  • 211 Views
  • Uploaded on

Alternative Retrieval Techniques What do you do when the documents are not English text Lecture Objectives Understand problems of dealing with multi-media data Know some solutions to those problems especially for image data Multimedia “documents” Text Hypertext Still Image Video Sound

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Alternative Retrieval Techniques' - Gabriel


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
alternative retrieval techniques

Alternative Retrieval Techniques

What do you do when the documents are not English text

lecture objectives
Lecture Objectives
  • Understand problems of dealing with multi-media data
  • Know some solutions to those problems especially for image data
multimedia documents
Multimedia “documents”
  • Text
  • Hypertext
  • Still Image
  • Video
  • Sound
  • Graphics
  • Hypermedia
metadata
Metadata
  • Data about data (documents)
  • Compare a Library Catalogue
    • author names, titles, subject, keywords
  • useful to search metadata rather than documents
conventional approaches to general image retrieval
Conventional Approaches to General Image Retrieval

Manual Tagging of text descriptions to images.

  • Costly, not very practical.
  • Rich content of images means that they may be indexed in very different ways.
problems of image indexing
Problems of Image Indexing
  • What is the concept of an image ?
  • Easy to extract low level features from images
    • colour, texture, shape
  • Hard to get from this to “Apples” let alone “Gridiron Football”
  • A picture may be interpreted in lots of ways
text indexing
Text Indexing
  • The words (terms) used indicate the concept/topic of the text
  • Most texts are fairly unambiguous
querying image vs text
Querying Image vs Text
  • Match query text vs extracted index from document
  • Generally users don’t have an example image
    • SCUD launchers
  • Which interpretation of the image are the users interested in ?
solutions
Solutions
  • Manual Indexing
  • Index by related text
  • Layout images according to low level features and provide browsing interface
  • Query by low level features
  • Combinations
example low level feature

Example Low Level Feature

Global Colour Histograms

global colour indexing
Global Colour Indexing
  • Identify a number of buckets in which to sort the available colours (e.g. red green and blue, or up to ten or so colours)
  • Allocate each pixel in an image to a bucket and count the number of pixels in each bucket.
  • Use the figure produced (bucket id plus count, normalised for image size and resolution) as the index key for each images.
global colour indexing16
Advantages:

Computationally fairly efficient and tractable at present

Comprehensible to users

Disadvantages

Users would prefer to search with keywords of objects or moods

Apparently similar images can have very different colour histograms: e.g. lighting

Global Colour Indexing
video indexing
Video Indexing
  • Background vs. Foreground
  • Finding Objects/People
  • Extracting Key Frames
  • Identifying Events for subsequent manual indexing
conclusions
Conclusions
  • Image Retrieval
    • hard to identify concept
    • hard to match/express queries
  • Global Colour Indexing
    • Useful, simple
  • Similar problems for other non-text media