Set Up Before You Judge
A dark room and a black screen make any LCD look worse. Dell says some light leakage is expected with dark backgrounds in dark rooms, and that those monitors work as designed. Set up the way Dell recommends:
- Put the monitor where you use it, at eye level, about an arm's length away.
- Leave the room a little lit, not dark. Dell inspects its monitors at 150 lux (typical office lighting), and gaming monitors at 70 lux.
- Let the monitor warm up for about 30 minutes.
- Set brightness to around 30–50% of its maximum.
Run the Check
- Open the monitor test full screen and step to the 10% Gray pattern, then Black.
- Look at the edges and corners from your normal seat.
- Move your head left, right, up, and down, and lean closer and farther away.
- Watch whether each bright patch changes, moves, or stays exactly where it was.
How to Tell Them Apart
Dell lists these differences:
- IPS glow changes with viewing angle and distance. It mostly affects the corners, and every IPS panel has some.
- Backlight bleed (Dell calls it light leakage) stays the same at any angle and distance. It can appear anywhere along the edges or corners, on any type of LCD.
LG gives the same test: glow depends on the viewing angle, and bleed doesn't. LG says glow at the corners from 40 degrees or more off-center is part of how IPS panels work and can't be changed.
LG also says edges that look a little darker than the center are by design, not a fault.
Is It Bad Enough to Report?
Dell suggests three steps before contacting support:
- Change the brightness. If the problem changes with it, it may be a settings issue.
- Open a bright app, such as a word processor. If the patch disappears, it's likely a brightness setting.
- If it stays, take a photo. Then compare with another monitor of the same model, showing the same image that isn't mostly black.
If your screen is clearly worse than the other one, Dell asks you to contact its Technical Support with the photo. LG says light that stays at every angle, or shows in a well-lit room, may be a defect that needs service.
Neither Dell nor LG lists pressing on the panel or loosening the frame as a fix. Contact the maker, or the seller if the screen is new and still within its return window.
Check the Rest of the Screen
While you have the monitor in front of you, run the dead pixel test for stuck or dead pixels. Step through the rest of the monitor test for banding, uniformity, and sharpness.
Hardware Test can't measure light output. Your eyes and a photo are the judge, so photograph the screen in the same light you use it in.