Screen Test
Dead-pixel, solid-pattern, and display-information checks in one tool.
Fullscreen recommended
How to Test
- •Open the Dead Pixel tab and step through each solid color at fullscreen, looking for dots.
- •Use the Patterns tab for gradients and grids that expose uniformity and banding.
- •The Screen Info tab reports your display’s browser-visible resolution and orientation.
Browser Limitations
- •A browser cannot read the physical panel; manufacturer specs may differ from what is reported.
- •One clean pass over one color does not guarantee a flawless panel — check every color.
Troubleshooting Tips
- •Mark persistent bright/dark dots across colors as genuine pixel defects.
- •Images that disappear on the next frame are likely software, not hardware.
About the Screen Test
The Screen Test uses your browser to render full-screen test patterns — solid colour fields, gradients, and contrast grids — so you can look for dead pixels, stuck subpixels, backlight bleed, and uneven panels. It works on anything the browser can draw to, from a laptop panel to an external monitor or a TV, making it the fastest way to evaluate a screen without installing anything.
Use it before accepting a new display delivery, after a drop or pressure damage, when shopping second-hand, or whenever text looks fuzzy and you need to determine whether the panel, the cable, or a system scaling setting is at fault.
Tips for a reliable result
- Set the display to its native resolution and the browser zoom to 100% before testing. This removes the most common sources of resampling — zoom, OS scaling, and overscan all shrink, stretch, or shift the pattern — but it does not make the mapping one-to-one, so treat the result as an inspection aid rather than a pixel-exact measurement.
- Clean the screen first; dust and fingerprints read as false dead pixels at close inspection.
- Inspect from straight ahead and then from a slight angle — some panel defects only appear off-axis.
- For pattern tests, enable fullscreen mode and step back about half a meter for the whole-panel view.
- Then inspect up close, section by section. A whole-panel glance from arm’s length can miss a lone stuck pixel entirely, so move your face close to the glass and work through the solid colour fields one region at a time, pausing on each. Zooming the browser is not a substitute for this: it redraws the pattern larger on screen but does not enlarge the panel itself, and it changes the mapping between rendered and physical pixels, which is the opposite of what you want when judging whether a single subpixel is stuck.
- Run the test on both dark and bright room lighting to reveal contrast and backlight differences.
Common problems and fixes
A pixel stays black on every color
That is a dead pixel. A pixel stuck on one color is "stuck" — sometimes fixed by rapidly cycling colors, but persistent faults are panel hardware defects covered by most manufacturer pixel policies.
Edges of the screen look brighter or cloudier
That is backlight bleed, common on LCD panels. Minor bleed is normal; severe glow visible in normal content justifies an exchange within the return window.
Colors look wrong on every pattern
A color filter is almost certainly active. Disable Night Light, f.lux, True Tone, Night Shift, or any hardware-accelerated color profile so the test patterns are the only thing shaping what you see.
The panel looks even but text and edges look fuzzy
Display scaling is the most common explanation, because a scaled framebuffer blurs everything the test draws. Set the resolution and scale to the panel’s native values in system display settings and run the test again — if the softness survives that, the cause is elsewhere and a single test page cannot tell you what.
Before you test
Any system
- Set the resolution to the panel’s native value and the browser zoom to 100% — this removes the most common sources of resampling, but it does not guarantee that a rendered pixel lines up with a single physical pixel.
- Disable Night Light / f.lux / True Tone — color filters change what patterns look like.
- Use a fullscreen browser window (F11) to hide interface chrome from the tested area.
FAQ
Can a screen test fix dead pixels?
No software can repair a physically dead pixel. Rapid color cycling occasionally revives stuck subpixels, but persistent defects are hardware — the value of the test is documenting them while your return or warranty window is open.
How small a defect can this detect?
It depends on your display settings and on how close you look. Solid colour fields are the most useful pattern for this, because a dead or stuck pixel stands out sharply against a flat field. But whether a single-pixel fault is actually visible at normal viewing distance varies with the panel, your seating distance, and any scaling in play — treat the pattern as something that helps reveal defects, not a promise that every one of them will be obvious from your chair. Move physically closer to the screen and work through the solid colour fields section by section, pausing on each region. Note that zooming the browser does not help here: it enlarges the rendered pattern, not the panel, and it further disrupts the relationship between rendered and physical pixels.
Does one rendered pixel equal one physical pixel?
Not reliably. Browser zoom, operating-system scaling, and display settings such as overscan or a non-native resolution all resample what the page draws, so a dot you see may cover several panel pixels and a panel pixel may never be drawn at all. Setting the browser zoom to 100% and the resolution to the panel’s native value removes the most common sources of resampling, but it does not guarantee a one-to-one mapping: subpixel layout, compositor rounding, and panel-side scaling can still shift it. If a count of defects matters — a warranty claim, say — confirm it up close and against the manufacturer’s own procedure.
Does it work on TVs and external monitors?
Yes — anything the browser can render to. Just remember TVs often apply motion smoothing and overscan that you should disable first, since both distort the pattern independently of the panel itself.