Dead Pixel Test

A dead pixel test fills your whole screen with solid colors one after another: red, green, blue, white and black. Against each flat color a faulty pixel gives itself away, because it is the only thing on screen that does not match. A dead pixel stays black on every color, including white. A stuck pixel keeps showing one fixed color while the background changes around it.

A stuck pixel is permanently lit in one color because a sub-pixel is fixed on, and it can sometimes be revived. A dead pixel receives no power at all and stays black on every color, including the white screen test, so it is usually permanent. The quickest way to tell them apart is a white field: a stuck pixel shows as a colored dot, a dead one as a black dot. Stuck pixels are worth attacking with the stuck pixel fixer before you write a panel off.

A dead pixel is not bad for the screen itself — it won't spread or harm the panel, and it's a permanent cosmetic flaw rather than a fault that grows. Whether it matters depends on how many there are and where: one near an edge is easy to ignore, a cluster or a spot dead-centre far less so. Manufacturers set their own dead-pixel limits for a warranty swap, so it's worth testing a new screen early and checking the count against that policy.

A stuck pixel can sometimes be fixed, though nothing is guaranteed. Rapidly cycling colors over the area with the stuck pixel fixer is the usual first attempt, and gently massaging the spot with a soft cloth while the screen is on sometimes frees it as well. Give either method several minutes rather than a few seconds. A truly dead pixel that stays black on white generally can't be repaired in software.

Dust and a dead pixel look alike at first, but they behave differently. Wipe the spot gently — if it moves or disappears, it's dust or a smudge on the glass. If it stays fixed in exactly the same place as the color screens cycle, it's a pixel fault. Clean the display before you start so dust isn't counted as a panel fault.