Apple publishes an article explaining ML improvements in Photos

Apple publishes detailed article explaining machine learning improvements in Photos app. In iOS 15 Photos app now can detect people with partially obscured faces.

This is done by combining face data with upper body information. This leads to better detection of people while still running on user’s device.

Apple Machine Learning Research: Recognizing People in Photos Through Private On-Device Machine Learning

Reference: Apple Explains How the Photos People Recognition Feature Has Improved in iOS 15