Row filters user mood for beautifying app

To its users, the photo app Meitu is an online surgery. It allows them to enhance how they look: thinner, bigger eyes, no wrinkles, even whiter.

To others, there are concerns that the free app's filters allow whitewashing, and questions about Meitu's collection of users' mobile data.

And to its China-based developer and stockholders, Meitu is now valued at $4.26 billion with more than 456 million monthly active users.