HTC Merge User Manual page 238

 Camera
Metering mode
Set how the camera measures the amount of light to calculate
the best exposure:

Spot metering mode allows the camera to measure light
around the focus point.

Center area mode allows the camera to measure light in the
center.

Average mode allows the camera to measure light in the
whole image.
Review duration
Set the time for a captured photo or video to be displayed on the
Review screen before the camera changes back to the Viewfinder
screen.
Flicker adjustment
When taking indoor shots under fluorescent lighting, keep this
setting on Auto or change it to the proper frequency (0Hz or
0Hz) of the power in your country to reduce flicker.
Auto Focus
This option enables or disables centered auto focus. Auto focus
is enabled by default.
Face detection
This option allows the camera to recognize faces and
automatically adjust the focus. Face detection will be turned off if
you disable Auto Focus