How to check for uneven corner lighting on a display

Does your screen look brighter in one corner, or do the edges seem cloudy when a dark picture is on screen? Uneven corner lighting can be a display setting, a viewing-angle effect, or a difference in the panel itself.

You can check the pattern with the Display Test. It shows color patterns that help you see whether the effect stays in the same place across different images and brightness levels.

Check the screen corners

1. Let the monitor warm up for about 20 minutes. Keep it in its usual position and view it from straight in front, at your normal sitting distance.
2. Open the Display Test and use its color test. Look at light, middle-gray, and dark patterns if available. Check each corner and the edges, not just the center.
3. Repeat the check at the brightness you normally use. If you usually use HDR or automatic brightness, note whether those settings are on, then compare with them off.
4. Look directly at the screen, then move your head slightly to the left and right. Note whether a bright or cloudy area stays fixed on the panel or changes as your viewing angle changes.

Use the room lighting you normally have, but avoid bright light reflecting off the screen. Do not press or rub a spot to see if it changes. Pressure can damage the panel.

What the result means

A corner glows on dark images, but changes with your viewing angle

This is often IPS glow, a viewing-angle effect on some LCD panels. It is usually most noticeable on dark gray or black screens and can shift or fade when you move your head. Sit directly in front of the display and use a little room light rather than judging it in complete darkness.

A bright patch stays in the same place on black

A fixed bright area near an edge may be backlight bleed on an LCD. The backlight is the light source behind the panel, and some of its light may show unevenly through the screen. If the patch remains in the same place from straight on and across several dark patterns, it is less likely to be only a viewing-angle effect.

Light gray or white looks cloudy or uneven

This can indicate uneven screen uniformity, meaning the screen does not show the same brightness across its surface. It may be subtle and may not matter for everyday browsing, but it can affect photo or video work where consistent brightness is important.

The effect appears only in a phone photo

A phone camera may exaggerate corner lighting. Its automatic exposure can brighten dark areas, and reflections or the camera angle can make the screen look less even than it does to your eyes. Use a photo only as supporting evidence. Judge the screen in person from your usual position.

The corners look even on the test patterns

The panel may be working normally, and the issue may come from a particular video, app, or screen setting. Check the same content on another display or use a different input source before assuming the panel is faulty.

What to adjust

1. Set a comfortable brightness. Very high brightness can make edge lighting more noticeable, especially in a dark room. On Windows 11, open Settings › System › Display and adjust the brightness control if your display provides one. On a Mac, open System Settings › Displays and adjust Brightness.
2. Turn off automatic changes for a comparison. Adaptive brightness can change the screen while you inspect it. On Windows 11, check Settings › System › Display › Brightness for automatic brightness options. On a Mac, check System Settings › Displays for Automatically adjust brightness, if available. Compare the screen with automatic adjustment on and off.
3. Compare with HDR off. HDR changes how the display handles brightness and dark tones. On Windows 11, open Settings › System › Display › HDR and turn off HDR temporarily, if the option is available. On macOS, open System Settings › Displays, select the display, and compare with its HDR setting off if one is shown.
4. Check the monitor's picture settings. Use the monitor's physical buttons or menu to check brightness, contrast, local dimming, and picture mode. Try the standard or default mode. Local dimming divides the screen into areas that adjust their backlight separately, which can make dark patterns look uneven.
5. Check your viewing position and reflections. Center yourself in front of the screen and remove strong light sources reflected in it. For a display that tilts or swivels, compare the screen at its normal angle with the screen positioned straight toward you.
6. Try another source. Show the same test patterns from another computer or connect the monitor to another device. If the same areas look uneven on the monitor's own menu and on different inputs, the cause is more likely to be the display than the computer or cable.

When it may be a panel problem

If a corner remains visibly brighter or cloudier from straight on, appears on several test colors, and stays in the same place with different devices, the display may have uneven panel or backlight illumination. A browser test can show the appearance, but it cannot measure the panel to a factory tolerance or diagnose the internal cause.

Check the monitor's return period or warranty before attempting any repair. Do not loosen the frame or press on the screen to try to spread the light. If the unevenness is severe and affects normal use, ask the manufacturer or a repair shop to assess it. For a new display, provide photos taken straight on along with a description of the brightness and pattern used.

Why dark screens make the effect stand out

On a black or dark gray image, even a small amount of light from an LCD backlight can be easy to notice. A bright desktop, a white page, or a lit room can hide that difference. OLED displays do not use a backlight, so backlight bleed does not apply to them, although their screens can still show other kinds of unevenness.

For a fair comparison, use the same pattern, brightness, viewing position, and room lighting each time.