What is a white screen used for?

[Mark Brown]

Checking Display for Dead Pixels
Because they don't light up, dead pixels are easiest to spot on a white background because they stand out. If you just got a monitor, you should turn on a white screen to make sure all of the pixels work.
Also, if you think your screen might have dead pixels, you can test it with a white screen. It works on any gadget and any size screen.
If you have any questions, you can use a different color screen, like a blank red screen, so that any difference stands out right away. This makes sure you get the best visual experience from your devices.
White Screen for Light
If you like to read at night, you can use your device's bright screen as a reading light. This website lets you turn on a white screen so you can read in the dark without waking others.