But, unlike age-guessers at carnivals, who look at a person's body, the software works by examining only the person's face.
"Age-estimation software is useful in applications where you don't need to specifically identify someone, such as a government employee, but would like to know their age," said Thomas S. Huang, the William L. Everitt Distinguished Professor of Electrical and Computer Engineering at the U. of I.
The software, said Huang, can be useful in many ways-age-recognition algorithms could stop underage drinkers from entering bars, prevent minors from purchasing tobacco products from vending machines, and deny children access to adult Web sites.
However, it's not easy to estimate someone's age, partly because the aging process is determined not only by a person's genetic makeup, but by many other factors as well, including health, location and living conditions.
"Human faces do convey a significant amount of information, however, and provide important visual cues for estimating age. Facial attributes, such as expression, gender and ethnic origin, play a crucial role in our image analysis," said Huang.
The age-estimation software was trained on a database containing photos of 1,600 faces, and consists of three modules - face detection, discriminative manifold learning, and multiple linear regressions.
It can estimate ages from 1 year to 93 years. It's accuracy ranges from about 50 percent when estimating ages to within 5 years, to more than 80 percent when estimating ages to within 10 years. Huang said that the accuracy can be improved by additional training on larger databases of faces.
Apart from performing tasks such as security control and surveillance monitoring, the software also could be used for electronic customer relationship management.
For example, a camera snapping photos of customers could collect demographic data - such as how many adult men and women buy burgers, or what percentage of teenagers purchase a particular soft drink.
Also, if combined with algorithms that identify a person's sex, age-estimation software could help target specific audiences for specific advertisements. For example, a store display might advertise a new automobile or boat as a man walks by, or new clothing or cosmetics as a woman walks by.
"All of this can be done without violating anyone's privacy. Our software does not identify specific individuals. It just estimates their ages," said Huang.