ViewSonic Q51 series Service Manual page 11

Contrast adjusts the difference between the image background (black level) and the foreground (white
level)
Brightness adjusts the background black level of the screen image.
Zoom expands and contracts the entire screen image.
Horizontal Position moves the screen image left or right.
Horizontal Size adjusts width of the screen image.
Vertical Position moves the screen image up or down.
Vertical Size adjusts the height of the screen image.
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User MENU 1
User MENU 2