LCDs pixels have different black to white (on- time) and white to black (off-time ). This results into a luminance unbalance at the reversal instant.
Luminance articfact was not present with previous CRT technology.
This example shows a Pattern Reversal Stimulus using same LCD, with and without IngEnesi VirtualCRT graphic controller.
In a real test, a simple sheet of paper in front of the display ( the round disk) can reveal the flashing at every pattern reversal
Traditional LCD graphic controller
IngEnesi VirtualCRT graphic controller