Dead Pixel Test

What is this tool?

The Dead Pixel Test fills the whole screen with one flat colour at a time. A pixel that is broken cannot show that colour, so it appears as a dot that does not match its surroundings — obvious on a plain field, invisible in a photograph or a web page.

Solid Colors covers Black, White, Red, Green, Blue, Cyan, Magenta, Yellow, Gray and Dark Gray. Display Uniformity adds a grey ramp — 5%, 10%, 25%, 50%, 75% and 90% — which is where clouding and patchy backlighting show up. Custom Colors lets you add your own hex values.

You are the detector. The tool presents the colours and records what you report; it does not scan the screen. That distinction is stated on the page itself under “Important Testing Limitations”.

How to use it

1. Clean the screen firstDust and dried specks look exactly like stuck pixels on a black field. Wipe the panel with a dry microfibre cloth before you start, otherwise you will chase smudges.
2. Go fullscreen and start with Black, then WhiteBlack exposes pixels stuck bright — they glow. White exposes pixels that are dead or stuck dark — they appear as specks. Those two colours find most faults on their own.
3. Step through Red, Green and BlueEach pixel is made of red, green and blue subpixels. A pixel with one failed subpixel looks fine on white but shows a coloured tint on the pure primary that it cannot render. Use Prev and Next, or Start Auto Test to advance automatically — the interval is 3 seconds.
4. Report what you saw on each colourThe buttons are ✓ No Issue, ● Suspected Dead, ● Suspected Stuck and ● Suspected Hot. They record your observation for that colour — the wording says “suspected” deliberately, because a visual check cannot confirm a hardware fault. Reset Reports clears them.
5. Finish with the uniformity greysSwitch to Display Uniformity and work through the grey steps. Faults that hide on pure colours — clouding, mura, a corner that is brighter than the middle — are easiest to see on 5% and 10% grey in a dark room.

What the results mean

Dead pixel

Stays black on every colour, including white. The pixel receives no power at all, so it is a permanent black dot. This is the one that does not come back.

Stuck pixel

Shows one fixed colour — red, green, blue or a mix — on every field. The subpixel is locked on rather than off. Stuck pixels sometimes recover on their own, or after gentle pressure or a rapid colour cycle, which is why they are worth distinguishing from dead ones.

Hot pixel

Stays bright white on a black field. All three subpixels are stuck on. It is the most visible fault type in dark content and the easiest to spot on the Black screen.

Clouding and uneven grey

Broad patches that are lighter or darker than the rest of the field, seen on the low greys. That is not a pixel fault at all — it is backlight uniformity, and the Screen Uniformity Test and Backlight Bleeding Test are the tools that cover it properly.

Your report summary

The counts reflect what you clicked, colour by colour. They are a record of your inspection so you can compare a panel before and after, or attach the observation to a warranty claim — not an automated measurement.

What it can detect

• Permanently black pixels on a white or coloured field
• Pixels locked to one colour across every test screen
• Bright pixels on a pure black field
• Single failed subpixels, which show only on the matching primary colour
• Clouding and grey non-uniformity on the low grey steps

Limits worth knowing

A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.

• The page carries a heading called “Important Testing Limitations”, and its FAQ asks “Can a browser automatically detect dead pixels?” The answer is no. A browser cannot read the pixels it just drew, so the detection is yours — the tool only supplies clean, uninterrupted colour fields.
• Browser and operating-system chrome may cover part of the screen unless you go fullscreen, and a fault hidden behind a taskbar cannot be found.
• The report records suspicions, not diagnoses. Confirming a pixel fault means comparing it against the manufacturer's own criteria, which usually specify how many faults are acceptable.
• Dust and screen damage are indistinguishable from stuck pixels by eye alone, which is why cleaning first matters.

Tips

• Test in a dim room. Reflections on a black screen hide bright pixels and invent dark ones.
• Sit at your normal viewing distance and then move closer. A fault you can only see from 20 cm away is unlikely to bother you in use, and most warranties reflect that.
• Use Custom Colors to add the specific shade a suspicious pixel seems locked to. That is the fastest way to confirm which subpixel has failed.

Troubleshooting

Related documentation

• DisplayScreen Uniformity TestA thirteen-step sequence across brightness, grey and colour fields, mapped to nine zones.
• DisplayBacklight Bleeding TestA pure black screen and a structured five-angle inspection for light leakage.
• DisplayDisplay Response Time TestControlled colour transitions for judging pixel response, trailing and overshoot by eye.
• DisplayScreen Flicker TestSteady and alternating fields for spotting flicker, at brightness levels you choose.
• DisplayScreen Ghosting TestHigh-contrast moving patterns that make trails and overshoot easy to see.