Iiyama ProLite TF1534MC User Manual page 24

Adjust the Phase to correct horizontal wavy noise, flicker or blur in the zebra pattern.
 In case the strong flicker or blurs remain on a part of the screen, repeat steps
NOTE
because the Clock may not be adjusted correctly.
 Adjust the H-Position after the Phase adjustment if the horizontal position moves
during the adjustment.
Adjust the Brightness and Color to get the desired picture after you complete the Clock
and Phase adjustments.
Put back your favorite wallpaper.
20 OPERATING THE MONITOR
and