How to test for dead pixels, and what can actually be fixed
Fill the screen with white, black, red, green and blue in turn and inspect each closely. A dead pixel stays dark on every color; a stuck pixel glows one color permanently; a failed subpixel only shows on the matching red, green or blue field, which is why checking a single color misses faults.
The short version
- Clean the screen first. A speck of dust impersonates a dead pixel convincingly. Wipe the panel down before trusting anything you see.
- Cycle the five fields. Show white, black, red, green and blue full screen, in a dim room, and inspect each slowly. Sit closer than usual; a single pixel is smaller than it sounds.
- Classify what you find. Dark on every field is a dead pixel. Lit on black is stuck. Visible only on one of red, green or blue is a single failed subpixel.
- Check the policy before the fixes. Manufacturers publish pixel-defect policies, and a new monitor inside its return window is a return, not a repair project.
Every pixel on your display is three lights: a red, a green and a blue subpixel, each with its own transistor. Most pixel faults are one of those three lights failing, which is why a proper test cycles through the colors instead of trusting one, and why "is it dead or stuck" is the first question worth answering. One of them is occasionally fixable. The other is not.
The five-field test
Clean the screen first, seriously. The most commonly diagnosed dead pixel is a speck of dust, and it has a perfect recovery rate once wiped off.
Then fill the display with white, black, red, green and blue in turn, full screen, in a dim room, and inspect each field slowly and closer than your normal viewing distance. Each field has a job. White drives all three subpixels fully, so anything dark against it is not being driven. Black turns everything off, so anything glowing against it is stuck on. The red, green and blue fields each isolate one subpixel across the whole panel, which is how you catch the subtle case: a pixel that looks healthy on white and black but has one failed subpixel, visible only when its color is the only thing asked for.
What each result means
A point that stays dark on every field is a dead pixel: its transistor is not driving, and no software can reach it. A point that glows on black is stuck: the subpixel is jammed on, usually red, green or blue, sometimes a pale mix. A point visible on exactly one of the color fields is a single dead or stuck subpixel, the most common fault and the easiest to miss.
The honest odds on fixing
Stuck pixels sometimes recover. The flashing method cycles colors rapidly over the fault, and the agitation occasionally frees the jammed liquid crystal. It costs nothing to try, it fails often, and because it strobes by design, nobody photosensitive should watch it run.
Dead pixels do not recover. There is no drive signal to restore from the outside, and any fix that claims otherwise is describing stuck pixels.
The pressure method, massaging the fault through a cloth, is the one we advise against. It has genuine successes and genuine casualties, and the casualties are pressure-damaged patches far more visible than the original fault. On a panel still under a return window or a defect policy, it also converts a manufacturer's problem into yours.
The policy question
Before any fixing, look up your display's pixel-defect policy. Manufacturers publish them, they specify how many faults of which kind justify a replacement, and a brand-new monitor with any pixel fault at all deserves a return rather than a repair attempt while the window is open. The test above takes two minutes; run it the day the monitor arrives.