One plus 3T - Manual (Page 9)

9 | What’s in the Box Device OxygenOS Safety Information
Camera
In difficult lighting conditions, High-Dynamic Range (HDR) is
automatically enabled to produce consistent, well-balanced photos.
Smile Capture eliminates the need for awkward arm-reaching.
Just smile to take great selfies, the OnePlus 3 camera takes care
of the rest.
Dynamic De-noise compares several frames of the same photo and
blends them together to reduce noise and improve clarity, instantly.
OIS, EIS, 16MP sensor, f/2.0 lens; enjoy all the features of a DSLR,
but none of the weight.