Canon Powershot A450 Advanced User's Manual page 15

Night Display
When shooting in dark conditions, the camera automatically
brightens the LCD monitor to suit the brightness of the subject*,
making it easier to frame the subject.
* Although noise may appear and the movement of the subject shown on the
LCD monitor may appear somewhat jagged, there is no effect on the
recorded image.
The brightness of the image displayed in the monitor, and the brightness of
the actual image recorded will be different.
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