FUZHOU -- One of China's leading photo apps has broadened its spectrum with the addition of skin testing function.

MTskin is built into Meitu app Cosmetics. Since it was released in October, over 25 million users have had their faces tested using the app, according to Xu Qingquan, CTO of the Meitu research center.

Meitu is one of the most widely used free photo editing apps in the world, and MTskin is based on a database of medical photos of facial problems. AI technology matches users' selfies with the problems and link them to professional dermatologists who deal with problems ranging from acne or chloasma to melanocytic nevi.

Guo Hui, a 32-year-old office worker, is a selfie lover. She now frequently takes selfies to check the pimples on her face.

"I was astonished when the app told exactly how many blackheads I had," said Guo, "I am also glad that it tells my skin's "age" is only 26."

Guo said the test only takes a few seconds to deliver a report.

The report comes with advice and recommends a range of expensive cosmetics.

"The AI uses data, algorithms and a deep learning platform coupled with our long experience of photo editing and human face technology," said Xu.

He admitted that the data base of facial problems needed to be expanded to improve the accuracy of testing, because a human doctor needs a lot more information than a mere photo. "As MTskin collects data it continually optimizes its algorithm. It will be the equal of human experts one day," he said, but so far MTskin just provides skincare tips.

"I don't think the results are totally reliable, but it is fun to know," said Guo.

Headquartered in Xiamen, Southeast China's Fujian province, Meitu is an innovator in mobile video and photography. Its selfie app can remove blemishes and brighten teeth. Its virtual makeup app allows users huge scope to experiment with new styles of makeup.

Established in 2008, the company has grown into one of the biggest tech companies in China, with its apps downloaded more than one billion times.

The company began its global expansion in 2016 and has since registered more than 500 million overseas users.