Image searching on the Web

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Image searching on the Web

• Qunyan Mao
• SIMS, UC Berkeley

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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 format

• BMP such as desktop wallpaper image, not
  supported by any Web browser
• PNG Portable Network Graphics. An image format
  for the future.

4
Image indexing

• Two methods used in indexing images
• text-based
• content-based

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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

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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

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Where to start

• Search engine
• general search engine AltaVista, Lycos,
• image search engine WebSEEK
• Specialized image database
• Museum, archive, and library digital image
  database

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How search engine work

• How does a Web search engine identify images and
  match to your criteria
• look for graphic files HTML tags and
  . Example AltaVista
• Look for caption HTML tag
• Look for title of Web page
• Employ human intervention to catalog images

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Search example Giraffe

• AltaVista
• Lycos
• WebSEEK

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AltaVista

• Http//image.altavista.com/cgi-bin/avncgi
• Text-based indexing file name and path name
• (live search demo)

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Lycos

• Http//lycospro.lycos.com
• Text-based indexing file name, path name and
  caption( tag)
• (live search demo)

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WebSEEK

• Http//www.disney.ctr.columbia.edu/webseek
• content-based image search engine
• (live search demo)

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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

14
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

15
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

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Before using the image

• Available for viewing doesnt mean available for
  reuse
• Make sure you have right to use it