Backlight Bleed Test

Observe a dark pattern for edge light leaks or viewing-angle-dependent glow under repeatable conditions.

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This check opens a focused test surface. You can return with Escape. Review what this browser test can and cannot measure.

Before you start

  • Begin in your usual room lighting and clean the screen according to its manual.
  • Choose a comfortable fixed brightness and start from a centered viewing position.
Step-by-step instructions

How to run this check

  1. Use a dark room and keep the display at a comfortable fixed brightness
  2. Start the black fullscreen pattern and view the screen straight on
  3. Look for bright patches at the corners and edges, then change your viewing angle
  4. Record the location and whether the patch moves or changes with viewing angle
  5. Judge what you can see directly; automatic camera exposure can exaggerate glow

Start with the view you actually use

A bright corner in a dark photograph is not enough to decide whether your screen needs service. Start in your usual room lighting, from your normal chair position, at comfortable brightness. If you normally play in a dim room, include that setup.

Write down the input, SDR/HDR state, picture preset, brightness setting, and any automatic brightness or local-dimming setting. Inspect the black pattern, then use the four comparisons below. Press Escape or Finish and record to open the observation form.

Change one thing, then return to the starting view

Use A → B → A: observe your starting setup, change one condition, then restore it. If the original appearance does not return, write “comparison inconclusive” and recheck the setup. Keep the same pattern, input, and display settings except for the item you are comparing.

  1. Room light: usual lighting → dimmer lighting → usual lighting

    Keep your chair and display brightness fixed. Note whether the patch becomes easier to see, or whether a lamp-shaped reflection disappears. If automatic brightness changes the screen output too, record that second change; the run did not isolate room light.

  2. Viewing position: center → slightly left or right → center

    Keep room light and brightness fixed. Move your head sideways without deliberately moving closer. Describe whether the patch spreads, fades, or shifts, and whether it returns at center. BenQ describes angle and distance effects on IPS glow; this observation alone does not identify your panel type.

  3. Display setting: baseline → one adjustment → baseline

    From the centered view, try one lower, still comfortable brightness setting and record both control values. A setting such as 30/100 is not a luminance measurement. Test a picture preset separately: changing preset and brightness together cannot show which change mattered. Record HDR and local-dimming states, and use the model's manual for its controls.

  4. Camera: direct view first, photograph second

    Write what you see before looking through the phone. For comparison photos, keep the camera position, lens, framing, and exposure fixed. Use the camera's focus/exposure lock if available; on iPhone, Apple explains AE/AF Lock. Record automatic or night-mode capture when used. Exposure lock helps repeat a capture; it does not turn the phone into a luminance meter.

Finish on real content

Restore your everyday setup. Reopen the same dark scene or application where the patch first bothered you, then compare a bright document. Note whether it remains distracting and exactly where. A black field reveals a condition; it does not represent every scene. Dell's troubleshooting sequence also checks brightness and bright applications, rather than relying only on a dark-room image.

Use the comparison to choose the next step

Several effects can overlap. A stationary patch is a location to record, not proof of backlight bleed; an angle-dependent patch does not rule out another issue at the same location.

Swipe the table sideways, or focus it and use the arrow keys.

Observations guide a repeat check; these are not hardware pass/fail thresholds.
What changed?What it suggestsWhat to do next
A lamp-shaped mark changes when that light moves or turns off.A reflection contributes to the appearance.Remove that reflection and repeat from center. Describe any patch that remains separately.
The patch spreads or fades off-axis, then returns at center.Viewing position contributes to the observation.Use the centered view as the reference. Record the direction of change; do not label a panel technology from this alone.
It is noticeable only on the black pattern in a darker room.Visibility depends on the content and room conditions tested.Compare the dark content you actually use in your usual lighting. Record “pattern only” if that is all you observed.
Lower brightness or another preset reduces it.That setting changes its visibility; this does not establish a repair.Restore the baseline to confirm the change. Keep a usable setting only after checking your ordinary content.
The same area remains distracting from center during normal use.You have a repeatable symptom worth documenting.Record the scene, location, and setup. Follow the exact model's diagnostic instructions and send the repeated observation to support.
Only the photograph looks dramatically brighter.Capture settings or processing may be affecting the evidence.Keep your direct-view note separate. Retake comparable photos; do not rank two screens using unrelated automatic exposures.

Save a comparison someone else can repeat

Use this outline in the observation Notes field. Fill only the checks you performed; leave the others as “not checked.”

Starting setup: model/input __; SDR or HDR __; preset __; brightness __; automatic controls __; room light and chair position __.

Comparison: patch at __; changed only __; appearance changed from __ to __; returning to the starting setup __.

Normal use: content/scene __; distracting, visible, or not noticed __. Direct view versus photo __; camera settings __. Not checked __.

Choose the saved appearance from what you saw directly, not from the most dramatic photo. If you cannot assess it consistently, close the form and repeat later. Select the saved observation in the report builder, add original photos and the model's details, and export before leaving.

If it remains distracting in the setup you need, check the seller's return deadline and the manufacturer's current support process. Manufacturer inspection conditions are product-specific; this page supplies no universal brightness, lux, or patch-size allowance. Do not press the panel or loosen its enclosure to try to change the result.

Comparison guidance reviewed . The sequence and recording outline are FreeScreenTest's practical synthesis of the linked manufacturer guidance, not measurements from a monitor we tested.

What this browser test can tell you

Can help you check

  • Visual observation and location notes on dark patterns.

Cannot measure

  • This test cannot measure objective luminance, apply a universal severity threshold, or diagnose the panel.

Interpret this observation

  • Record the location, size, and viewing angle of any bright patch you can see.
  • Room light, display brightness, viewing angle, panel mode, and camera exposure can change or exaggerate the apparent glow.
  • Exact luminance and uniformity measurements require a calibrated luminance meter or imaging photometer.
Setup and sources

Recommended setup

  1. Start in normal room lighting at a comfortable fixed brightness and a centered viewing position.
  2. Then change only room light, viewing position, or one picture setting, and return to the baseline.

Sources

Methodology reviewed: