[gwern]

I thought it would be dlib since that's open-source and very easy to use, but it's actually the Microsoft face recognition API, according to their paper: "Photo Sleuth: Combining Collective Intelligence and Computer Vision to Identify Historical Portrait", Mohanty et al 2018 http://crowd.cs.vt.edu/wordpress/wp-content/uploads/2018/04/...

[geephroh]

For anyone who wants to mess around with Face API, MS has a simple python implementation along with a sample desktop app here:

https://github.com/Microsoft/Cognitive-Face-Python