The software developed at Pennsylvania State University not only tags the images, but also improves the tags by "learning" from users' interactions with the system.

"What is novel with the 'Tagging over Time' -- or T/T technology -- is that the system adapts as people's preferences for images and words change," said Associate Professor James Wang, lead researcher of the project.

In other words, the system can accommodate evolving vocabulary and interpretations to images people have uploaded and are uploading to systems such as Yahoo's Flickr, Wang said.

"The bottom line is that the system makes it easier to find photographs and is able to improve its performance by itself as time passes," said Ritendra Datta, a graduate student working with Wang. "The advancement means time savings for consumers as well as improved searching and referral capabilities."

The system, which included research by former graduate student Dhiraj Joshi and Associate Professor Jia Li, was presented last month in Augsburg, Germany, during the annual meeting of the Association for Computing Machinery.