For a quick dark field with an optional timer, open the Black Screen page.
How to inspect a laptop or monitor
Start with a clean screen in a dim room, not necessarily a completely dark room. Remove reflections from lamps and windows before deciding whether a bright patch belongs to the display. Sit centered at your usual distance and set the screen to a comfortable everyday brightness. Select Black, enter fullscreen, and look at the corners and edges for broad bright areas that remain in the same position. The RGB selector changes the test image, not your panel's backlight brightness.
Switch to the near-black and dark gray fields. A region that looks prominent on absolute black may be much less noticeable in normal shadow detail. Compare all fields with the same room light, viewing position, and physical brightness setting. Hide pattern labels when inspecting a subtle patch, then restore them to record the code value. Exit with the visible Exit button or Escape. On devices without native fullscreen, the expanded browser view may retain browser controls.
Interpret edge glow without overcalling a defect
Backlight bleed describes unwanted light leakage in a backlit LCD, often around an edge or corner. A browser can provide a useful dark image, but it cannot isolate leakage from every other cause of a visible glow. Off-axis glow on some LCD panel types can change substantially as you move your head. Gently change your viewing position without pressing the bezel or twisting the panel. If the effect follows your position, viewing-angle behavior may be contributing.
OLED pixels do not use an LCD backlight, so a gray patch on an OLED requires a different interpretation. Reflections, near-black processing, panel uniformity, and temporary image retention can also affect the view. A phone photograph is only a record of that camera's exposure and processing. Long exposures often make a barely visible region look dramatic; comparing photos with different exposure settings is not a reliable severity test.
Decide what to check next
Repeat the observation after the display has been operating normally for a while and compare it with a familiar dark scene. Record the brightness setting, room lighting, field code, and whether the feature moves with your viewing angle. If a fixed bright patch distracts you in ordinary content, consult the display maker's support or return policy with consistent observations. Do not apply pressure, loosen a frame, or assume that a web pattern can repair light leakage. Use the viewing-angle test for position-dependent changes and the uniformity test for broader gray-field variation.
Example: a fixed edge patch or a changing corner glow?
Suppose a pale patch stays near the lower edge on Black and Dark gray. Return to your centered seat after a small head movement and check that same location. If the patch remains conspicuous there, record it as a persistent edge patch for further inspection. If a corner glow changes strongly as you move, record the viewing position too. Both effects can coexist; neither observation alone identifies a panel fault.
For a useful support report, describe the field selected and whether the patch is distracting in an ordinary dark scene at your normal brightness. A camera that raises exposure can exaggerate its appearance, so do not use a brighter photograph as evidence that leakage has worsened. Never press the corner or flex the frame to try to make the patch disappear.
Frequently asked questions
Does this page measure backlight bleed?
No. It supplies steady digital fields for visual inspection. It cannot measure emitted light, panel tolerances, or defect severity; those require suitable instruments and a defined assessment method.
What brightness should I use?
Begin at your normal comfortable display brightness and record it. You can compare another setting deliberately, but maximum brightness in total darkness may exaggerate effects that are inconspicuous during ordinary use.
Is corner glow always backlight bleed?
No. Viewing-angle glow, reflections, local dimming behavior, and other panel characteristics can look similar. Move your head and compare several dark fields before describing the observation.
Can I test an OLED here?
You can inspect its black and dark gray appearance, but OLED has no LCD backlight. Use the uniformity test to explore gray-field patches or banding and avoid calling every bright area backlight bleed.
Why does my photo look worse than the screen?
Automatic exposure and image processing can brighten dark areas. Keep exposure and room conditions consistent, and base practical severity on what you see during ordinary viewing rather than a long-exposure image.