How to compare screen contrast with room lights off

A screen can look punchy in a bright room and washed out with the lights off. You may also notice gray-looking blacks, details disappearing in shadows, or bright patches around the edges. Those observations can come from the display, its settings, or the room itself.

Use the Display Test to view color patterns in a dark room, then compare what you see under consistent conditions. This is a visual check, not a measurement of the screen's contrast ratio.

Compare screen contrast in a dark room

1. Open the Display Test on the screen you want to check. If you have more than one display, make sure you are looking at the intended screen.
2. Turn off the room lights and any lamp shining toward the screen. Close curtains if outside light reflects on the panel. Give your eyes a minute to adjust before judging dark areas.
3. Open the color test and look at its black, white, and gray patterns. Check whether black areas look dark, whether light areas look distinct, and whether you can see neighboring dark gray shades instead of one solid black area.
4. Look at the screen straight on, then move slightly to the left and right. Note whether dark areas or shadows change noticeably with your viewing angle.
5. If comparing two screens, show the same pattern on each. Set both to a comfortable brightness and compare them from the same angle. Do not assume their brightness sliders use the same scale.
6. Turn the room lights back on and look again. If the result changes substantially, note the room lighting along with the screen settings. That helps you tell a viewing-environment issue from a display issue.

Keep the screen's contrast, color, and dynamic picture settings unchanged during the first comparison. Change one setting at a time afterward so you can tell what made a difference.

What the result means

Black looks gray across the whole screen

The screen may have limited black levels, or its brightness may be set too high for a dark room. A bright reflection can also make black appear gray. Check for reflections first, then lower the screen brightness a little and repeat the same pattern. A browser test cannot tell you the display's exact black level or contrast ratio.

Dark gray shades blend together

The darkest steps may be crushed, which means several dark shades look like the same black. A contrast or gamma setting, an HDR mode, or a display profile may be changing the image. Check whether the issue appears in other content too. If it only happens in one app or video, the problem may be that content rather than the screen.

One corner looks brighter or has a glow

Uneven backlighting or light escaping around an LCD panel can show more clearly on a black screen in a dark room. Some glow may also change as you move your viewing angle. Repeat the check straight on, with no light reflecting on the screen. A pattern that stays in the same place is more likely to be a display characteristic than a browser setting.

Contrast looks better with the lights on

Ambient light can make a bright screen easier to view, but reflections and room lighting can also reduce the apparent difference between black and white. If you prefer the screen with some light, use a soft lamp behind or beside it rather than a bright light aimed at the panel.

How to improve the comparison

1. Remove reflections. Wipe dust from the screen with a clean, appropriate cloth and change your position if you can see a lamp or window reflected in it. Do not press hard on the panel.
2. Set a comfortable brightness. On Windows 11, open Settings › System › Display and adjust the brightness control if your display provides one. On macOS, open System Settings › Displays. A lower brightness can make a dark-room comparison more comfortable, but it does not increase the display's actual contrast ratio.
3. Turn off automatic picture changes for the comparison. On Windows 11, check Settings › System › Display › Brightness & color for automatic brightness or content-based brightness options, if available. On macOS, check System Settings › Displays for Automatically adjust brightness or True Tone, if available. These options can alter how the image looks as conditions change.
4. Check the monitor's picture settings. Use the monitor's physical controls to look for options such as dynamic contrast, local dimming, black level, or a picture preset. Temporarily disable dynamic adjustments if you want a steady comparison, then restore any setting you prefer.
5. Check HDR and color settings. If the display or operating system is using HDR, compare with HDR both on and off, changing nothing else. On Windows 11, HDR options are under Settings › System › Display. The available controls depend on the display and graphics hardware.
6. Repeat the test in another browser or on another device. If a pattern looks wrong only in one browser, an app or browser display setting may be involved. If the same area looks wrong on several devices, the screen itself becomes a more likely cause.

When it may be a screen problem

A browser color test can reveal visible differences, but it cannot confirm a panel defect or measure a calibrated contrast ratio. Browser rendering, display profiles, HDR processing, and the monitor's own processing all affect what you see. If the same bright patch, glow, or crushed shadow detail appears with different sources and settings, photograph it in a dim room and contact the manufacturer or seller if the display is under warranty. For a persistent defect outside warranty, ask a repair shop whether the panel can be serviced. Some LCD glow is a normal viewing-angle effect, so compare from a typical seated position before deciding it is faulty.

For a fair comparison, keep the room lighting, viewing angle, content, and screen brightness as consistent as possible.