Monitor Test Online – Pixels, Color & Sharpness

Use the live Display Lab to inspect a monitor with black, white, red, green, blue, gray, gradient and sharpness patterns. Fullscreen mode helps cover the visible panel, while the browser reports screen size, viewport size, device pixel ratio and colour depth. These are visual screening tools—not calibrated measurements of colour accuracy, luminance, contrast, response time or panel quality.

When to use the full display test

Checking a new, used or repaired monitor before the return period ends.
Investigating a spot, tint, band, soft edge or scaling problem seen in normal use.
Comparing a laptop panel with an external display under the same browser conditions.
Separating an obvious panel mark from dust, reflections, software scaling or source processing.

Prepare the screen first

Clean the panel safely and inspect it from more than one angle.
Let the display warm up, disable temporary night-light or colour filters and use its native resolution where known.
Choose comfortable brightness in a room without strong reflections.
Keep browser zoom at 100% for sharpness comparisons and record any scaling setting you change.

How to run a complete monitor inspection

Start with black. Enter fullscreen, allow your eyes to adjust and look for pixels that remain bright, obvious backlight leakage or reflections that move when your viewing angle changes.
Check white and gray. Look for dark points, dirt, broad tint changes and obvious brightness variation. Repeat after cleaning before treating a mark as a pixel fault.
Inspect red, green and blue separately. Scan the entire panel at a comfortable distance. A subpixel fault can be easier to see on one primary-colour field than on white.
Review the gradient. Look for unusually abrupt steps, crushed ends or colour transitions. Compare another browser, input source or display mode if banding is unexpected.
Use the sharpness pattern. Check whether fine detail is consistent across the panel. Softness or moiré can indicate scaling, overscan, non-native resolution or display processing.
Read the screen information carefully. Compare the browser-exposed screen and viewport values with your operating-system settings, but do not treat them as guaranteed panel specifications.
Repeat suspicious observations. Leave fullscreen, change only one variable—cable, port, browser, scaling or display mode—then rerun the same pattern.
Choose a focused diagnostic. Use the dedicated pixel, refresh-rate, motion-ghosting or resolution tool when the broad inspection points to one symptom.

What each test pattern can reveal

Pattern	Useful observation	Important limit
Black	Bright or stuck pixels, obvious glow/leakage and reflections.	Room light, viewing angle, local dimming and panel technology strongly affect black appearance.
White	Dark pixels, dust, broad brightness variation and obvious tint.	A browser field is not a calibrated white point or luminance measurement.
Red, green and blue	Subpixels that remain dark, bright or the wrong colour on a primary field.	The page cannot identify the electrical cause or guarantee warranty classification.
Gray	Broad uniformity, tint changes, image retention and dirty-screen effects.	Camera photos can exaggerate banding or moiré; inspect with your eyes first.
Gradient	Visible tonal steps, crushed ends or processing changes.	Banding may originate in the GPU, source depth, browser, cable path, display processing or panel.
Sharpness	Scaling softness, overscan, uneven fine detail and processing artifacts.	The pattern does not measure optical sharpness, pixel response time or motion clarity.

Interpret the reported screen values

Screen: the CSS-pixel screen dimensions exposed by the browser.
Viewport: the current page area, which changes with browser chrome and window size.
Pixel ratio: the browser ratio between device and CSS pixels; scaling can affect it.
Colour depth: a browser-reported value, not a colourimeter result or proof of the active end-to-end bit depth.

New-monitor acceptance checklist

Inspect all solid fields from your normal viewing distance and close up.
Check corners and edges as carefully as the centre.
Repeat black-uniformity checks in normal room light and a dimmer room.
Confirm native resolution, scaling and refresh-rate settings in the operating system.
Save the model, serial number, date and repeatable symptom before contacting support.

If the result looks wrong

Change one variable at a time. Compare a different cable or port, verify native resolution, disable overscan and image-enhancement modes, and test another browser or computer. If the same fixed pixel or region appears on every source and pattern, document it against the manufacturer's pixel policy.

Browser and measurement limits

GearCheck Lab renders CSS patterns through the operating system, GPU, browser and display pipeline. It cannot read panel electronics or measure luminance, Delta E, gamut, contrast ratio, response time, input latency, subpixel voltage or uniformity numerically. Browser screenshots also cannot prove a physical panel defect.

Choose the focused display diagnostic

Dead Pixel & Screen Quality Test Screen Resolution Checker Display Refresh Rate Test Monitor Ghosting Test Monitor & Display Testing Guide

Monitor test FAQ

Can an online monitor test confirm a dead pixel?

It can help you visually locate a pixel that stays dark, bright or the wrong colour across several solid fields. Clean the screen and repeat the pattern before concluding the mark is a panel defect.

Can these patterns repair a stuck or dead pixel?

No. GearCheck Lab provides visual inspection patterns and does not claim to repair pixels or alter panel hardware.

Why does a gradient show visible steps?

Banding can come from source colour depth, GPU output, browser rendering, display processing, compression, the panel or an intentionally reduced-quality mode. Compare another browser or source before blaming the panel.

Are the reported resolution and colour depth hardware specifications?

No. They are browser-exposed screen and viewport values. Operating-system scaling, browser zoom, multiple displays and remote sessions can make them differ from the panel's native specification.

Does fullscreen make the test calibrated?

No. Fullscreen removes interface distractions and covers more of the panel, but it does not calibrate colour, luminance, contrast, response time or uniformity.

Does a clean result prove the display is perfect?

No. It means no obvious issue was seen with these browser-rendered patterns in this viewing session. Intermittent faults, subpixel behavior and calibrated performance still require other equipment or manufacturer diagnostics.

Privacy and safe use

LOCAL VISUAL TEST: The test patterns are rendered in the browser and the displayed screen information comes from browser APIs; the inspection does not require uploading a screenshot or image of your display.

Use comfortable brightness and stop if a high-contrast pattern causes discomfort. This page does not change monitor firmware, calibration profiles or operating-system display settings.