Image capture and tutor

According to Zhou Xin, an associate researcher on AI studies at the Institute of Software, Chinese Academy of Sciences, what such apps use is multimodal radar and three-dimensional vision technology, combined with non-contact sensing techniques and high-sensitivity wearable sensors, which are capable of deeply analyzing users' motion data and physiological signals through deep learning and AI.

In simpler words the smartphone camera "catches" the movements of the user, turns them into models in which the limbs are represented by virtual sticks, analyzes whether they match the standard movements and sends feedback to the user, Zhou said.

"The technology is not very new. It has long been used in animations that catch an actor's movements, make a model out of it and give it a new skin so that on screen it looks like a bear," he said.

Even Black Myth: Wukong, the newly developed game based on Chinese classic literature that is making waves in the international game market, has utilized the same technology to build models for its characters. For example, the agile movements of General Tiger, one of the game's characters, were lifted from a real cat.

It's because of the rising popularity of smartphones that the technology can be accessed by everybody at his/her home. However, Zhou explained, the feature requires that the user's smartphone have a High-Density (HD) camera that can capture the user's movements accurately in time, and a fast chip that can process the captured images and video clips in an efficient manner, so that the user can receive feedback in real time.

Besides, the AI technology is constantly improving so that the user feels he or she is facing a real person, not AI. To achieve that, the app manufacturers record a set of movements carried out by real models and design the algorithm in such a way that when a user wants to see how to twist his frame to one side, the model on his smartphone telling him how is actually reenacting what was first recorded on a real model.

But don't forget the potential legal risks, says Cui Zhendong, a senior lawyer based in Zhengzhou, capital of Henan province. As any user concerned about his/her privacy should worry, it is worth asking what exactly happens to the images captured by the app.

"To use these apps, the user needs to authorize the apps to access the camera, which will take pictures and make videos of him/her," Cui said, "It's necessary to minimize the risk of them getting leaked."

The user agreements of several such apps promise to keep the collected information secret, but more protection is needed for the user, Cui said.