Black Screen

How to use a black screen

A pure black field asks the display to switch every red, green, and blue subpixel off. On an LCD, the backlight behind the panel stays on, so any light that escapes where it should not stands out against the black. On an OLED display, each pixel makes its own light, so a pixel showing black gives off no light at all.

1. 1

   Dim the room. Room light reflects off the panel and hides faint leaks. Check in a dark room, or at least turn off the lights behind you.

2. 2

   Open it full screen. The bright browser toolbars around the field make the edges and corners harder to judge.

3. 3

   Use your normal brightness. At maximum brightness, any leak looks stronger than it does in everyday use.

4. 4

   Look from your usual seat. Face the center of the display at your normal distance, then check the edges and corners without leaning in.

What a black screen can reveal

Backlight bleed on an LCD looks like brighter patches along the edges or in the corners that stay in the same place when you move your head. It is light escaping around the edges of the panel.

Glow is a lighter haze in the corners that changes or fades when you change your viewing angle. It is common on IPS panels and is not the same as bleed.

A stuck pixel shows up as a bright red, green, blue, or white dot that stays lit on black. Confirm it with the Dead Pixel Test.

Some unevenness is normal on many LCDs, so compare what you see with the manufacturer's warranty terms before deciding a panel is faulty.

Photos exaggerate light leaks

In a dark room, a phone camera raises its exposure, so bleed and glow look much stronger in a photo than they do to your eyes. Judge the display by eye. If you need to show a fault to a seller, take the photo with the same room light and brightness you used for the check.

For a closer look at the edges, use the Backlight Bleed Test. To check the bright end of the panel, open the White Screen.

This screen's exact value has its own #000000 color page, with its RGB and HSL values and its contrast against black and white.