Apple has published its latest machine learning journal entry with a new article detailing the challenges of implementing facial detection features while maintaining a high level of privacy.

The new journal entry explains how the facial detection algorithm works locally on your iPhone without relying on information leaving your device:

That requires the right hardware resources to pull off while maintaining efficiency:

Apple launched its machine learning journal over the summer and has published multiple entries including one on how “Hey Siri” works on iPhone and Apple Watch. You can read the complete latest entry here.