Set up the room before the screen
Set the room and screen to conditions you normally use. Dim strong reflections, but do not treat a fully dark room and maximum brightness as the only valid inspection condition.
Record brightness and viewing position. A dark-field patch can look different when either changes, so compare at your usual settings before calling it a defect.
Clean the panel using the manufacturer's instructions before inspecting a tiny point. Dust or a surface mark can resemble a pixel fault. Do not press or rub a suspected defect.
Set browser zoom to 100% for fine patterns. Does a mark move when you clean the surface or change the pattern? Record that observation.
Run the monitor test patterns in order
Open the screen test and enter fullscreen from its control. Cycle through white, black, red, green and blue, recording the location and colour where a point differs.
Inspect the same point on more than one field. A dark point on white and an unusual colour on a primary are observations, not enough to determine which subpixel or component failed.
Mark positions while the pattern is visible. Repeat at normal brightness and seating distance so a surface speck or temporary rendering issue is less likely to be misread.
Use the screen bleeding test for a black-field comparison. Change viewing angle without changing brightness. IPS glow and bleed can look similar, and a camera exposure is not a reliable substitute for your own view.
For OLED, the OLED screen test can compare temporary image retention. Follow the display maker's own static-image and maintenance guidance; the browser does not repair burn-in.
Dead pixels, bleed or glow?
A point that remains at the same location across patterns deserves a closer check. Photographing it may help record its position, but camera processing cannot classify the panel defect.
For dark-field changes, compare your usual brightness and viewing position with a second controlled view. No universal amount of bleed or glow determines every manufacturer's policy.
A browser pattern is a visual inspection. If the symptom also appears in normal work, record the pattern, conditions and model for support.
What a monitor test in a browser cannot see
The browser displays patterns but cannot inspect panel electronics or apply a manufacturer's pixel classification. Scaling, colour management and ambient light affect what you see.
Uniformity needs calibrated equipment and controlled conditions for a numeric claim. This checklist records a visible observation, not a measured brightness map.
A page cannot run firmware maintenance. For refresh timing, use the separate monitor refresh rate test, which samples browser animation frames rather than certifying panel hardware.
Return, claim or keep the monitor
Compare a repeatable finding with the exact model's current pixel policy or support terms. Policies differ; do not assume a fixed number of allowed defects.
If the monitor is new, record purchase and return dates and contact the seller or manufacturer using the observed evidence. Eligibility depends on the actual terms.
If the finding changes with angle, brightness or content, record those conditions before seeking support. Do not declare the panel normal or faulty from one black-field view.
Symptom table
| Symptom | Likely layer | Next action |
|---|---|---|
| Dark point across colour fields | Pixel issue or surface mark is possible | Clean safely, then repeat several fields |
| Bright patch near an edge | Bleed, glow or exposure difference is possible | Compare normal brightness and viewing angle |
| Point differs on one primary | Subpixel or rendering difference is possible | Repeat red, green and blue at the same position |
Common questions
How do I test a monitor for dead pixels?
Use the screen test in fullscreen and compare white, black, red, green and blue at the same location. Clean the surface safely first. A browser observation alone cannot classify the panel electronics.
How many dead pixels before a monitor can be replaced?
There is no universal number. Check the current pixel policy for your exact model and seller terms; record the point and pattern before contacting support.
Is backlight bleed a defect?
A bright area on a dark field needs context: normal brightness, viewing angle and ordinary content. The browser cannot decide whether it meets a specific manufacturer's defect policy.
How do I test a monitor for ghosting?
Use a motion pattern or the maker's recommended test if available, then compare the same display mode and content. Does the trail persist in one application only? The static colour check does not measure pixel response time.