A dead pixel test and fix routine works best when inspection comes first and repair comes second. A "dead pixel" is a single subpixel or a small cluster on an LCD, OLED, or other flat-panel display that no longer responds to the signal the panel receives, so the point appears stuck dark, stuck bright, or stuck on one color regardless of what the image should be. The Dead Pixel Test is a browser-based visual aid that fills one large panel with eight exact solid sRGB colors — black, white, red, lime, blue, cyan, magenta, and yellow — so you can sweep the surface with your eyes and look for points that do not match the surrounding field. The tool does not promise to repair anything, flash the panel, apply pressure, or modify operating-system settings. Its job is narrower and more honest: render a controlled stimulus, label the exact requested color, and let you record what you see. The actual fix — repair, replacement, or warranty escalation — belongs to the manufacturer's diagnostic and warranty process, which is the appropriate authority once you have clear visual evidence in hand.
What the Dead Pixel Test actually checks
The Dead Pixel Test is built around a deliberately simple contract: render one large panel filled with a single solid sRGB CSS color at a time, label that color with its exact hexadecimal value, and let you advance through a fixed sequence using the keyboard or mouse. The panel is rendered from an immutable eight-row fixture, and each row is one of the eight colors defined in the W3C CSS Color Module Level 4 named-color table. Because the values are explicit product data — not approximate theme colors — the progress line you see on screen always names the current pattern, its position in the sequence, and the exact sRGB CSS value being requested, such as #000000 for black or #00ffff for cyan.
The test is therefore a request, not a measurement. The W3C specification defines the CSS color value; it does not certify the physical light a particular monitor actually emits. Browser color management, the operating-system display profile, HDR modes, the panel's gamut, scaling, subpixel layout, viewing angle, local dimming, image enhancement, burn-in protection, and any hardware calibration can all change what reaches your eye. The tool identifies the stimulus it asked for; it does not claim to read the panel's response back as a number. Treat anything you see as visual evidence to bring to a qualified diagnostic, not as a measured color reading.
Run the test step by step
The full procedure takes a few minutes and needs only a clean screen and a browser tab. The Dead Pixel Test runs entirely on your device, so no screenshot, profile, or observation ever leaves the tab.
- Clean only the outer display surface using the manufacturer's safe method — usually a dry microfiber cloth, or a cloth lightly dampened with water or a screen-safe solution — so dust, smudges, and surface marks are not mistaken for panel defects.
- Open the Dead Pixel Test page and select Start fullscreen test to request a larger browser presentation. The browser can decline the request because of permissions, embedding, platform limits, or user settings; if that happens, the in-page panel still cycles through every color.
- Inspect each of the eight patterns in turn: black, white, red, green-channel lime, blue, cyan, magenta, and yellow. Click anywhere on the panel, press Space, or use the left and right arrow keys to move forward and backward through the sequence. Navigation wraps in both directions so you cannot get stuck on one pattern.
- For each pattern, slowly scan the center, edges, and corners. Different solid fields make different mismatches easier to notice — a dark spot stands out on white, while a stuck bright spot stands out on black — so a mismatch that hides on one color often shows on another.
- Note any stationary mismatch that persists across several colors and against the outer surface after cleaning. Stationary is the key word: a point that stays in the same physical location across multiple patterns is a stronger signal than one that follows content.
- Exit fullscreen normally using the browser's usual Escape behavior. Do not apply pressure, tap the panel, run a rapid-flash "fixer" animation, or install untrusted repair software because of what you saw. Exit and decide.
- Send the result to manufacturer diagnostics before any repair decision. The visual check tells you what to escalate; the manufacturer's own test pattern, warranty terms, and authorized service decide what happens next.
The eight color patterns and what each reveals
The sequence is fixed, ordered, and labeled. The table below lists the eight patterns in the order the tool serves them, together with the exact sRGB CSS value the panel is asked to render. These are the values the W3C CSS Color specification defines for the named colors used here; the green row is the full green channel, which CSS names lime, not the darker named color green at #008000. The MDN named-color reference lists the same values for browser-side documentation.
| Position | Pattern | Requested sRGB CSS value | What it tends to reveal |
|---|---|---|---|
| 1 | Black | #000000 | Stuck bright subpixels and bright reflections on the panel surface |
| 2 | White | #ffffff | Stuck dark subpixels and dark dust or pressure marks that survived cleaning |
| 3 | Red | #ff0000 | Green or blue subpixels that fail to dim on a fully red field |
| 4 | Lime (full green channel) | #00ff00 | Red or blue subpixels that fail to dim on a fully green field |
| 5 | Blue | #0000ff | Red or green subpixels that fail to dim on a fully blue field |
| 6 | Cyan | #00ffff | Red-only subpixel defects visible only on combined green and blue channels |
| 7 | Magenta | #ff00ff | Green-only subpixel defects visible only on combined red and blue channels |
| 8 | Yellow | #ffff00 | Blue-only subpixel defects visible only on combined red and green channels |
The reason for visiting every channel, including the three secondaries, is that each pattern stresses a different combination of the three subpixels. A defect on a single subpixel often hides on the color that channel normally drives at full brightness and only shows up on a color that should not contain that subpixel at all. Skipping patterns therefore hides information, which is why the tool cycles through all eight and gives each one its own inspection window.
Reading the results without jumping to conclusions
A visible mismatch on a solid color is a starting point, not a verdict. Several non-panel causes can produce something that looks like a dead pixel:
- Dust, lint, fingerprints, or a screen protector can sit on the outer surface and absorb or scatter light in one spot. The manufacturer's safe cleaning pass is meant to rule these out before any deeper conclusion.
- Reflections from a window or a bright lamp behind you can sit on the same spot on every pattern and look stationary even though they are not part of the panel.
- Image retention, burn-in, and stuck subpixels can look similar to dead pixels but have different causes and different remedies.
- Browser zoom, scaling, subpixel layout, GPU output, cable faults, and remote-display compression can all add visible artifacts that disappear when the panel is fed the same color from a different source.
- A screenshot is useful for separating content-generation problems from physical panel problems with care: a physical defect generally does not become part of a screenshot, while a rendering defect often does. If a spot is in the screenshot, it is likely upstream of the panel.
The tool is deliberately a visual aid. It renders eight documented CSS sRGB colors, supports forward and backward navigation with wraparound, and asks the browser for fullscreen only on your direct action. It does not force kiosk mode, hide operating-system controls, disable sleep, change brightness, alter display settings, or override the browser's normal Escape behavior. It is also a static test on purpose: no rapid strobe, no seizure-risk animation, no instruction to apply pressure, and no promise that any pattern will repair a defect.
Why the tool does not promise a fix
The phrase "dead pixel test and fix" is common in search, but the two halves answer very different questions. The test half is something a controlled visual aid can do well: present known colors, label them, and let a human eye compare each pattern against the surrounding field. The fix half is a hardware decision that belongs to the manufacturer, the panel vendor, and the warranty that covers the display.
The Dead Pixel Test is built not to blur that line. It does not flash the panel rapidly, ask you to press on the screen, heat the panel, install third-party repair software, or follow a destructive pixel-fixing claim. It records nothing on a server, asks for no account, and uploads no screenshot, color profile, display identifier, observation, or navigation history. The current pattern index exists only in the tab and resets when the page reloads. The reliable contract is narrow and stays narrow on purpose: render eight documented CSS sRGB color values in a large focusable panel, support forward and backward wraparound, request fullscreen only after direct user action, and clearly separate a visual aid from hardware diagnosis or remediation.
When manufacturer diagnostics take over
Once you have a clean visual record, the next step is the manufacturer's own diagnostic routine. Built-in display test patterns, hidden service menus, and authorized service tools exist for a reason: they feed the panel a known signal from inside its own signal chain, with the original color profile, scaling, and image processing in place. A mismatch that survives manufacturer diagnostics is then covered by the panel's dead-pixel policy, which typically spells out how many defects of which kinds at which positions qualify for repair or replacement under warranty.
Stop using the display and follow qualified manufacturer guidance if you see spreading damage, electrical symptoms such as flicker that gets worse, visible impact damage, or any safety concern such as a hot spot, smell, or sound from the panel. The visual check is meant to support that decision, not to replace it. A clean record is also useful — it tells you, and the manufacturer, that the panel passed an independent eight-color visual sweep, which is the kind of baseline worth keeping for future comparison.