Facial recognition technology （人脸识别技术） is widely used today. For example, the police use it to search for bad guys. It's also used to unlock phones or doors.
Now, a similar technology, known as facial detection（探测）, is entering a new field: the business of advertising（广告）.
Such systems are going through tests in a small number of stores. One facial detection system can judge （判断） a person's "happiness" or "fear" level. Another system can detect whether someone is wearing eyeglasses. If so, stores can send advertisements for new glasses to him.
Facial detection technology is also placed inside some large advertising boards. Cameras in those boards can detect（探测） information like people's ages and five levels of feelings - from "very happy" to "very unhappy".
Supporters of the technology say it could improve buyers' experience by showing products they might like or by offering them products at lower prices.
Some are against the idea of using such systems. Pam Dixon, the head of a privacy（隐私） group, s one of them. She thinks the strange actions may cause something unfair. For example, a store could raise the price of a product according to a person's age and feelings.
However, one store testing the technology explained people's information like names or ages wouldn't be stored. And the advertising board system maker said it didn't keep any personal information or record any videos.
