Simplicity Eases Image Retrieval
UNIVERSITY PARK, Pa. -- A picture is worth a thousand words, but
computerized searches for a digital image involve only a few because
they examine only the key words or descriptions attached to an image. A
new method that looks at the picture itself, however, may soon change
the way images are classified, sorted and retrieved.
A new search method employs soft similarity to compare image files
by content, rather than attached key words. The technique could find an
application in searchers of medical image databases.
James Z. Wang, an assistant professor of information
sciences and technology at Pennsylvania State University, is developing
an algorithm that indexes and compares digital image files based on
their content. While similar image-retrieval systems have been proposed
and developed, Wang's approach offers some improvements. For example,
it divides images according to type, such as outdoor scenes, biomedical
images or astronomical pictures. Then only the most relevant features
and characteristics for each kind of image are used.
The technique employs soft similarity, in which the
most similar regions in two images are matched. The program softens the
match criteria and widens the comparison to include the entire image.
All regions are thus taken into consideration, avoiding problems that
arise when images are arbitrarily segmented for evaluation.
Wang and his team have constructed an experimental
image-retrieval system, called Simplicity, which runs on a standard
server. They have tested the system on a database of about 200,000
general-purpose images and a library of more than 70,000 pathology
On the Web
According to Wang, Simplicity is faster and more
efficient than existing image-retrieval methods, and it offers higher
performance. He said that it could be extended to the estimated billion
images on the World Wide Web and that a variation of the technique
could be used to filter unwanted material, such as pornograpic images.
For now, the researchers are working with biologists,
physicians and other experts to make the system more useful for medical
An online demonstration of Simplicity, which Wang
developed while he was a graduate student at Stanford University in
Stanford, Calif., is available online at wang.ist.psu.edu.
by Hank Hogan
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