Dell IN1930 User Manual page 25

This feature will help reduce minor cases of image retention.
LCD Conditioning
If an image appears to be stuck on the monitor, select LCD Conditioning to help eliminate any image retention. Using the LCD Conditioning
feature may take some time. LCD Conditioning feature cannot remove severe cases of image retention or burn-in.
NOTE: Use LCD Conditioning only when you experience a problem with image retention.
The below warning message appears once user selects "Enable" LCD Conditioning.