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Image searching on the Web. Qunyan Mao SIMS, UC Berkeley. Image on the Web. More images on the web Format of image GIF: CompuServe Graphics Interchange format, a dominant web format JPEG: support “true color”, ideal for photographs TIF: large file size, not well suited for web pages.

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image searching on the web

Image searching on the Web

Qunyan Mao

SIMS, UC Berkeley

image on the web
Image on the Web
  • More images on the web
  • Format of image
    • GIF: CompuServe Graphics Interchange format, a dominant web format
    • JPEG: support “true color”, ideal for photographs
    • TIF: large file size, not well suited for web pages
image format
Image format
  • BMP: such as desktop wallpaper image, not supported by any Web browser
  • PNG: Portable Network Graphics. An image format for the future.
image indexing
Image indexing
  • Two methods used in indexing images
    • text-based
    • content-based
text based vs content based
Text-based vs content based
  • Text-based : commonly used image indexing and searching method
    • descriptive text
    • controlled vocabulary
  • Drawbacks:
    • have to have descriptor along with the image to make it accessible
    • consistency: different type of textual data
    • human intervention
text based vs content based1
Text-based vs.. content based
  • Content-based indexing and searching
    • goal: provide algorithms that can automatically recognize the important features in an image without human intervention
    • search by color, shape,spatial relationship
where to start
Where to start
  • Search engine:
    • general search engine: AltaVista, Lycos,
    • image search engine: WebSEEK
  • Specialized image database:
    • Museum, archive, and library digital image database
how search engine work
How search engine work
  • How does a Web search engine identify images and match to your criteria
    • look for graphic files: HTML tags: <img src> and <href>. Example: AltaVista
    • Look for caption: HTML tag<alt>
    • Look for title of Web page
    • Employ human intervention to catalog images
search example giraffe
Search example: Giraffe
  • AltaVista
  • Lycos
  • WebSEEK
altavista
AltaVista
  • Http://image.altavista.com/cgi-bin/avncgi
  • Text-based indexing: file name and path name
  • (live search demo)
lycos
Lycos
  • Http://lycospro.lycos.com
  • Text-based indexing: file name, path name and caption(<ALT> tag)
  • (live search demo)
webseek
WebSEEK:
  • Http://www.disney.ctr.columbia.edu/webseek
  • content-based image search engine
  • (live search demo)
specialized image database
Specialized image database
  • Museums, archive, and library digital image database
    • Fine arts museums of San Francisco http://www.thinker.org/imagebase/index-2.html
    • California heritage collection http://sunsite.berkeley.edu/CalHeritage/collection.html
    • National Museum of America Art
problems in using search engines
Problems in using search engines
  • Search result heavily relies on the how the webmaster name the image file and directory.
  • Even with the content -based search, there are a lot unexpected results
specialized image database1
Specialized image database
  • More likely use controlled vocabulary to describe the image
  • well organized comparing to the other images on the Web
  • have their own search tools or find aids
before using the image
Before using the image
  • Available for viewing doesn’t mean available for reuse
  • Make sure you have right to use it