Dead Pixel Test: Find, Diagnose, and Fix Dead or Stuck Pixels
A single misbehaving pixel on a new monitor has ruined more evenings than most software bugs. The good news: finding one takes about two minutes, and figuring out what kind it is tells you immediately whether it can be fixed, whether it’s covered by warranty, or whether you should learn to stop seeing it.
The two-minute test
Run the dead pixel test on the device you want to check. It fills the screen with solid colors — black, white, red, green, blue, cyan, magenta, yellow, and gray — and you advance through them with a click or the space bar.
Before you start, wipe the screen. This isn’t a joke; a good share of “dead pixels” reported to manufacturers are specks of dust, and a microfiber cloth is cheaper than return shipping.
Then go color by color and scan the whole panel, corners included. Sit closer than you normally would. A defective pixel on a 27-inch 4K display is about 0.15 mm across — at normal viewing distance your eye slides right past it unless the surrounding field makes it obvious. That’s exactly what the solid colors are for.
Reading what you find
Where a spot shows up tells you what it is:
| What you see | Where it shows | Diagnosis |
|---|---|---|
| Black dot | On white and all bright colors | Dead pixel — no power reaches it |
| Red, green, or blue dot | On black | Stuck subpixel — one channel frozen on |
| White dot | On black | Hot pixel — all three subpixels on |
| Colored dot on one specific color only | E.g. green dot on pure red | Stuck subpixel, identified by elimination |
| Fuzzy patch bigger than a pixel | Usually on white or gray | Dust, pressure damage, or delamination — not a pixel defect |
The subpixel logic is worth understanding because it’s how you diagnose by elimination. Every pixel is three light valves: red, green, blue. On a pure red screen, healthy pixels show only their red subpixel. If a green dot glows there, that pixel’s green valve is stuck open. On a black screen — all valves shut — anything glowing is stuck. On white — all valves open — anything dark is dead.
The full taxonomy, including what display standards say about acceptable defect counts, is in Dead vs stuck vs hot pixels — and what warranties cover.
What can actually be fixed
Dead pixels: effectively nothing. A pixel that receives no drive signal is a hardware fault — a failed transistor or a broken trace. No software can route electricity through a broken connection. Anyone selling a “dead pixel repair app” that promises otherwise is selling you a color flasher and hope.
Stuck pixels: sometimes, genuinely. A stuck subpixel is usually a liquid crystal cell that stopped responding to voltage changes, and two folk remedies have real (if anecdotal) track records:
- Color cycling. Rapidly flashing colors on the stuck area for 10 minutes to a few hours. The theory is that constant state changes coax the crystal material back into responding. There’s no controlled study either way — what exists is twenty years of forum reports, some of them convincing, many of them cases that might have resolved on their own.
- Gentle pressure. Screen off, soft cloth, light fingertip pressure on the stuck pixel, then power on while releasing. The operative word is gentle — pressing hard on an LCD can damage the very layers you’re trying to fix, and on OLED it can do worse. If you try this at all, treat it like handling a lens, not like resetting a joint.
Give a stuck pixel a few cycling sessions over a couple of days. If it hasn’t moved by then, it won’t. At that point your options are the warranty route or acceptance — and honestly, for one stuck subpixel in a screen corner, acceptance has a lot going for it.
Hot pixels: treat like stuck ones, with lower expectations.
OLED is a different story
On OLED panels each subpixel emits its own light, so a “dead” OLED pixel is a genuinely dark one and shows best on white. Stuck-on OLED subpixels are rarer than on LCD. What OLED adds instead is burn-in — persistent ghosting of static content — which is uneven wear, not a pixel defect, and shows up as patterns (taskbars, logos) on the gray and solid-color screens rather than as single dots.
When to escalate
If the pixel is dead (not stuck), if there’s more than one, or if the defect sits in the central area of the screen, check the manufacturer’s pixel policy before doing anything else. Policies differ enormously — some makers replace a panel for a single bright pixel, others require five or more defects — and where the pixel sits often matters as much as how many there are. Take a photo with a ruler or coin for scale on the color that shows the defect best; support will ask.
And if you’re checking a screen you’re about to buy secondhand, run the test before the money changes hands — here’s the full pre-purchase routine.