Display Diagnostics Hub
TEST YOUR DISPLAY BEFORE YOU TRUST IT
A new monitor can look impressive on a desktop wallpaper and still have a stuck pixel, uneven panel area, the wrong refresh-rate setting or motion behavior you dislike in games. An older display can develop similar symptoms gradually. The most useful browser-based check is therefore a sequence: inspect static defects first, confirm the browser-visible frame cadence, then compare motion behavior under repeatable settings.
This guide connects GearCheck Lab’s focused display diagnostics into one workflow. The tests are visual and browser-based. They can reveal repeatable screen problems and configuration clues, but they do not replace factory calibration equipment, a colorimeter, photodiode response-time testing or manufacturer warranty criteria.
A repeatable new-monitor and display check
If you are testing a new monitor during a return window, run the same sequence before changing many image-processing options. That gives you a useful baseline and makes later comparisons easier.
- Set the display to its intended resolution and refresh setting.
Check the operating system first. Browser tests cannot correct an OS configuration that is sending the display the wrong mode. - Clean the panel.
Dust and fingerprints can look surprisingly similar to dark pixels or uniformity marks. Use appropriate display-cleaning guidance before deciding a spot is inside the panel. - Inspect solid colors in fullscreen.
Use the Dead Pixel & Display Quality Test to cycle black, white, red, green and blue. Check both a normal viewing distance and a closer inspection distance. - Inspect gradients and sharpness patterns.
Use the broader Display Test for grayscale/gradient transitions and sharpness patterns. Look for obvious banding, clipping, scaling softness or unusual tint changes rather than trying to perform color calibration by eye. - Measure browser-visible refresh cadence.
Run the Display Refresh Rate Test with the tab focused and minimal background load. Repeat the measurement if the result is unexpectedly low or unstable. - Compare motion behavior.
Use the Monitor Ghosting & Motion Test and compare the same pattern while changing one monitor setting at a time, such as overdrive. Look for the direction and severity of trailing, not a fake laboratory response-time number. - Repeat anything suspicious.
Reload the page, confirm browser zoom/scaling, check another cable or input where relevant, and repeat before treating one visual observation as a confirmed defect.
Choose the display diagnostic that matches the question
Full Display TestUse as the broad visual inspection suite for solid colors, grayscale/gradient behavior, sharpness and general screen information.
Open full display test → Dead Pixel & Quality TestUse when searching for dark, bright, stuck or wrong-color pixels and obvious panel uniformity problems on solid fields.
Open dead pixel test → Display Refresh Rate TestUse to estimate the cadence the browser is actually receiving and to catch obvious configuration mismatches such as a high-refresh display operating near 60 Hz.
Open refresh-rate test → Monitor Ghosting & Motion TestUse to visually compare motion trails, smearing and inverse-ghosting behavior between monitor settings under the same browser pattern.
Open ghosting test → Dead, stuck and bright pixels: inspect across several colors
A single fullscreen color is not enough to characterize every pixel fault. A pixel or sub-pixel may behave differently depending on which color channel is being requested, so cycle through black, white, red, green and blue.
A point that appears dark on white may be easier to confirm on other bright fields. A bright point on black can indicate a different visible failure pattern. A colored point that refuses to match the surrounding field can behave like a stuck sub-pixel. Browser tests can help you locate the visual defect, but they cannot tell you which transistor or sub-pixel circuit has failed.
Panel warranty policies vary by manufacturer, model, pixel location and defect type. A browser test can document what you see; it cannot determine whether a specific warranty policy requires replacement.
Uniformity, bleed and viewing conditions
Solid black, gray and white fields can reveal uneven brightness or tint, but room conditions matter. A dark room makes edge glow and backlight leakage easier to see, while an extremely bright exposure in a phone photo can exaggerate effects that are less visible in normal use.
LCD technologies can also change appearance with viewing angle. OLED panels have different uniformity and retention characteristics. Compare the display from your normal seating position before judging a panel from an extreme angle.
Use browser patterns as a consistent visual stimulus. Do not interpret them as calibrated luminance measurements unless you are also using suitable measurement hardware.
What a browser refresh-rate test actually tells you
A browser can timestamp animation frames and estimate how frequently the page receives opportunities to draw. This is useful because a monitor advertised at 144 Hz, 165 Hz or 240 Hz may still be configured by the operating system to run close to 60 Hz. A stable browser result near the lower setting is a strong reason to re-check OS display settings, cable capability and selected monitor input mode.
| Observation | Likely interpretation | Next check |
|---|
| High-refresh monitor measures close to 60 Hz repeatedly | The current desktop/browser cadence may really be around 60 Hz. | Check OS advanced display settings, selected resolution, cable/input capability and monitor menu. |
| Result alternates widely between runs | Browser scheduling, background load, power saving or variable refresh behavior may be affecting samples. | Focus the tab, close heavy background work and repeat several times. |
| Measured value is slightly below a familiar nominal rate | Small timing differences and nominal conventions are normal. | Look for a stable cluster rather than demanding one exact integer on every sample. |
| Browser result matches the intended mode but games feel capped | The desktop display path may be correct while the game has its own FPS/VSync/refresh configuration. | Check the game and GPU settings separately. |
Browser refresh measurement is not an oscilloscope or direct panel scan-out measurement. It is a practical configuration check based on page frame timing.
Ghosting, smearing and inverse ghosting
Ghosting is seen as a trail or smear behind moving content when pixel transitions do not settle quickly enough for the motion being shown. Dark transitions on some VA panels can produce especially visible smearing. Aggressive overdrive can create a different artifact—overshoot or inverse ghosting—where a bright or dark halo appears on the opposite side of the transition.
The useful browser workflow is comparison: keep the animation speed and background the same, then change one monitor overdrive setting and observe whether the trail becomes cleaner or develops stronger overshoot. There is rarely one perfect setting for every refresh rate.
The GearCheck motion test deliberately avoids claiming a response time in milliseconds because accurate panel response measurement requires optical hardware and controlled methodology.
Sharpness, scaling and browser zoom
If text or fine patterns look soft, first confirm the display is running at its native resolution and that browser zoom is appropriate. Operating-system scaling can be intentional and useful on high-density displays, but non-native display resolution can introduce resampling that makes fine patterns less crisp.
Sharpness controls in a monitor can also add halos or edge enhancement when pushed too far. Use a fine pattern to compare settings, but judge normal text and real content as well. A synthetic pattern is a diagnostic aid, not the final image-quality goal.
What browser display diagnostics can and cannot establish
Strong use caseFullscreen defect inspection, visible banding/sharpness patterns, browser-visible frame cadence and repeatable motion comparisons.
Useful comparisonBefore/after monitor settings, different cables/inputs, different refresh modes or a new panel versus an older display under similar conditions.
Needs instrumentsColor accuracy, luminance, HDR peak brightness, exact gamma, response time, input lag and calibrated motion-performance claims.
Browsers are excellent at presenting consistent visual patterns and measuring page timing. They are not spectroradiometers, colorimeters, high-speed cameras or photodiodes. GearCheck Lab keeps these boundaries explicit so a convenient online test does not become a false laboratory claim.
New monitor return-window checklist
- Confirm native resolution and intended refresh rate in the operating system.
- Check black, white, red, green and blue fullscreen fields.
- Inspect gray and gradients for obvious uniformity/banding problems you can see in normal use.
- Run the refresh-rate test several times with the tab focused.
- Compare ghosting at the monitor’s default overdrive setting, then one setting higher/lower if available.
- Try the inputs and cables you actually plan to use.
- Photograph any repeatable visible defect for your own return/warranty documentation.
- Read the manufacturer’s pixel-defect and warranty policy before assuming one pixel guarantees replacement.
When a “display problem” may be upstream
Not every visible issue originates in the panel. A limited cable or adapter can prevent high refresh modes. GPU driver settings can change color range or refresh selection. Browser zoom and OS scaling affect sharpness. Video compression can create banding that is absent in a generated gradient.
When possible, compare a generated GearCheck pattern with another app and repeat using a different port, cable or device. A fault that appears only in one application or source path should be isolated before the monitor itself is blamed.
Monitor and display testing FAQ
Can a browser test prove a monitor is defect-free?
No. It can expose many visible defects and configuration problems, but it cannot measure every optical/electrical specification or guarantee that a subtle fault will never appear under other conditions.
How do I check a new monitor for dead pixels?
Clean the screen, use native resolution, open fullscreen solid black, white, red, green and blue fields, and inspect the whole panel. Repeat any suspicious point across multiple colors before deciding it is a pixel defect.
Why does my 144 Hz or 165 Hz monitor show about 60 Hz?
First check the operating system’s selected refresh rate, resolution, cable/input capability and monitor settings. Browser timing can be affected by system conditions, but a repeatable result close to 60 Hz is a reason to check configuration.
Can the ghosting test measure response time in milliseconds?
No. It can help you visually compare trails, smearing and overshoot between settings. Accurate response-time measurement needs calibrated optical equipment and a controlled method.
Does a black screen prove backlight bleed?
No. Viewing angle, room darkness, brightness setting and camera exposure all affect appearance. Use the pattern to inspect from your normal viewing position and compare what is visible during real dark content.
Should I test with HDR on or off?
For a baseline defect check, use the normal desktop mode you actually use most often. HDR changes tone mapping and brightness behavior, so treat HDR evaluation as a separate configuration comparison rather than mixing it into the first baseline.
Run the test that matches the symptom
If you are checking a brand-new display, start broad and work through the full sequence. If you already know the symptom, jump directly to the focused diagnostic.