A fullscreen black screen for checking backlight bleed, IPS glow and clouding on a new monitor, laptop or TV. Darken the room, go fullscreen and look at the edges and corners. A near-black screen shows uneven patches more clearly.
How to test for backlight bleed
- Dim or switch off the lights in the room and wait a minute for your eyes to adjust.
- Set your monitor's brightness to the level you normally use; at full brightness every screen shows some bleed.
- Press F for fullscreen, and keep the cursor still so it hides.
- Look straight at the screen from your normal seat. Then press → for the near-black screen to look for clouding.
Bleed, glow or clouding?
- Backlight bleed
- Light leaking in from the edges or corners. It stays in place when you move your head.
- IPS glow
- A silvery or warm glow in the corners that changes or fades as you move your head. Normal for IPS panels.
- Clouding
- Patchy, uneven brightness across a dark screen. Easiest to see on the near-black screen.
Is it worth returning?
Some bleed is normal on LCD screens, especially IPS. It matters if you can see it in normal use, such as dark films or games with the lights on. Taking photos with a phone exaggerates bleed, so judge with your eyes. To check pixels too, open the dead pixel test.
Questions
Do OLED screens have backlight bleed?
No. OLED pixels make their own light, so a black screen is truly black. Use the dead pixel test on OLED instead.
Can backlight bleed get better?
Slight bleed from pressure on the panel sometimes eases. Loosening the stand or the screws on the back of a monitor can help, but may affect the warranty.
How do I go fullscreen?
Press F on a keyboard, or use the fullscreen button in the bar at the bottom. Press Esc or F again to leave. On iPhone, Safari does not allow real fullscreen, so add the page to your home screen for the cleanest view.