Dead vs stuck pixel: how to tell, and what can be fixed

The three kinds of pixel defect

Each pixel on an LCD or OLED screen is made of red, green and blue subpixels. A defect affects one or more of them.

• Dead pixel: stays black on every colour. All subpixels are off. Most visible on a white screen.
• Stuck pixel: stays red, green, blue or a mix such as yellow or cyan. One or two subpixels are always on or always off. Visible on some colours and not others.
• Hot or bright pixel: stays white or very bright on every colour. Most visible on a black screen.

How to tell them apart

1. Open the dead pixel test in full screen.
2. On white, a black dot is a dead pixel or a stuck pixel missing subpixels.
3. On black, a bright dot is a hot pixel or a stuck subpixel that is always on; its colour tells you which.
4. On red, green and blue, a stuck subpixel shows as a dot that is too bright or missing on exactly one or two of these colours.

A pixel visible only on one colour is almost always a stuck subpixel, not a dead pixel.

Subpixels and screen types

Why a pixel can be wrong on only one colour: a white pixel is red, green and blue subpixels lit together. If the red subpixel is stuck on, the dot looks red on black and pinkish on white, and normal on red. If the green one is dead, the dot looks magenta on white and black on green.

On OLED screens each subpixel makes its own light, so a dead subpixel is truly dark. On LCD screens a backlight shines through the subpixels, so a stuck-open subpixel is very bright on dark backgrounds. On some panels the subpixels are not arranged in simple stripes, so a defect can look slightly larger or oddly shaped up close. Use a magnifier or your phone camera zoom to see the subpixels if you need to be sure.

Dust, scratches or pressure marks?

• Dust or dirt sits on the surface: wipe gently with a dry microfibre cloth. If it moves or disappears, it was not a pixel. Dust usually looks grey and fuzzy and is visible on every colour.
• Dust under a matte coating or inside the panel looks like a soft, slightly blurred dot or a small shadow, larger than one pixel. Change your viewing angle: a shadow inside the layers shifts slightly, a pixel does not.
• Pressure marks look like a lighter or darker patch, often around a point where the screen was pressed. Check them with the monitor uniformity test.
• Clusters: several defective pixels together or a line of them point to physical damage or a panel fault rather than a single pixel.

Can dead or stuck pixels be fixed?

Dead pixels: no. A pixel that receives no power or has a broken transistor does not come back with software. The realistic options are the retailer's return window, warranty service under the manufacturer's pixel policy, or living with it.

Stuck pixels: sometimes. A stuck subpixel can recover on its own over days or weeks of normal use. Some people report that it recovered after running a flashing-colour tool, but there is no reliable evidence that flashing works, and it never works on dead pixels.

Hot pixels behave like stuck ones: sometimes they recover, often they do not.

What pixel fixer tools actually do

Dead pixel fixers and stuck pixel fixers, including JScreenFix-style sites, flash a small area or the whole screen through rapid colours. The idea is to exercise a stuck subpixel until it switches normally again. It cannot reach a dead pixel, and it cannot repair burn-in or image retention, which are different problems (see burn in vs image retention).

If you try one anyway:

• Do not use flashing tools if you or anyone watching is sensitive to flashing light. Rapid flashing can trigger seizures in people with photosensitive epilepsy.
• Run it for short sessions and check the result on the matching colour afterwards.
• Do not press or rub the screen hard to push a pixel back; it can create more damage than it fixes.

TestDock does not offer a flashing fixer. The dead pixel test uses solid colours to find and document defects.

What to do next

1. Document the pixel: its position, the colour on which it shows, and a photo with lowered exposure.
2. Check again after a few days of normal use, in case a stuck pixel recovers.
3. If the screen is new, check the retailer's return window and the manufacturer's pixel policy for your model. Policies differ by brand, model and pixel type.
4. For a full check of a new screen, follow how to test a new monitor.