Inspect a dark field for bright edges, corner glow, and uneven patches, then compare what you see with normal viewing.
Start this test
Start at your usual display brightness. Use the black and gray references to separate a persistent patch from reflections or a change in viewing angle.
Select a pattern, open fullscreen, and compare the same area of your display.
Local visual check. No upload or installation.
Reference drawing is unavailable. Try another browser to run this test.
View the screen from your normal centered position. In fullscreen, hide controls for an unobstructed black field.
Reference follows the current browser pixel ratio.
← → Change reference F FullscreenH Hide or show controls
Tap the fullscreen pattern to hide or restore controls. Press Escape or use Exit to leave fullscreen.
Black and gray references reveal different behavior. Keep your viewing position and monitor settings steady while moving between them.
The black reference requests RGB 0 across the drawing. In fullscreen, hide the toolbar with H or tap the pattern for a clear field. Look for bright dots, persistent light near an edge, or broad corner glow. A bright-looking area needs comparison with other conditions before its cause can be identified.
The 5% and 10% gray references request RGB 13 and 26 respectively. They can make dark patches or tint easier to compare than full black alone. Their percentages describe approximate RGB code levels. They do not set the monitor’s brightness or mean that the panel is emitting that percentage of its maximum light.
The 50% gray field requests RGB 128. Compare whether a patch stays in the same area as the reference becomes lighter. Use the same normal viewing distance. This helps describe the observation more precisely, but it cannot measure uniformity, assign a tolerance, or decide whether a panel meets a warranty policy.
The most revealing condition is not always the most representative one. Start with how you actually use the display and record any changes.
Open the test with the display mode and brightness you normally use. Let the screen reach a steady state and remove obvious reflections where practical. Raising brightness to its maximum can exaggerate dark-field differences. If you change a setting, return to the same reference before comparing the result.
Reduced room lighting can help locate a dark-field feature, but also compare it in your usual room and content. Sit centered, then change your viewing position slightly. A glow that changes strongly with angle is a different observation from a bright edge that stays in the same place.
Enter fullscreen and hide its controls so interface elements do not distract from the field. Tap the pattern or press H to restore them. Switch to dark gray and then mid-gray without changing several other conditions at once. Note which references show the feature and whether it is visible in ordinary use.
Several effects can look similar in a photograph or a quick glance. These comparisons are more useful than treating every bright corner as the same issue.
Viewing-angle-dependent glow, persistent edge light, and reflected room light can overlap. Compare the location and shape while changing only your position or lighting. A visual browser field cannot distinguish these effects automatically. If the result matters for support, describe the conditions rather than submitting only a label such as backlight bleed.
Automatic camera exposure can make a dark screen look much brighter than it does to your eyes. A photo can help document location, but it is not a calibrated measure of severity. Compare the display directly in normal content and use consistent conditions if you take more than one photograph.
LCD panels use a backlight, while OLED displays do not use an LCD-style backlight. An OLED concern may be more visible on a near-black or gray reference than on pure black. Use the gray fields to describe uniformity, and consult guidance for the actual display technology instead of applying the same backlight explanation to every screen.
A dark-field comparison helps you locate and describe an effect. It does not produce a measured defect score.
Not automatically. Brightness, room light, viewing angle, panel technology, and the content can all affect the appearance. Compare the same area under ordinary-use conditions and on more than one reference. For a service or return decision, use the manufacturer’s model-specific guidance rather than a universal threshold from a browser test.
No. A darker environment can make subtle differences easier to see, but it can also exaggerate features that are inconspicuous during normal use. Start at your usual brightness and compare the result in familiar room lighting. Manufacturer inspection conditions may differ, so a pitch-black-room impression is not a general pass/fail rule.
No. The page draws black and gray references and gives you controls to compare them. It cannot read emitted light, change the backlight, adjust panel electronics, or fix a physical issue. Use repeatable observations to decide whether another source, display setting, or a support comparison is useful.
The reference value is an RGB code requested by the browser. The monitor’s brightness control, tone response, processing, and surrounding light determine how bright that code appears. A 50% gray code is not a promise of half the measured luminance, and changing the reference does not move the hardware brightness control.
Use the reference that matches the question you want to answer.
