Dead Pixel Test

How to read the result

Work through each color full screen and look closely at the whole panel. A dead pixel stays black on every color, including white, because it receives no power. A stuck pixel stays one fixed color, so it shows up as a bright red, green or blue dot on a black field.

Stuck pixels can sometimes be freed by cycling colors quickly for several minutes. Dead pixels cannot be fixed in software. Check your warranty: most manufacturers only replace a panel once a certain number of dead pixels appear.

What dead pixel test does

A dead pixel test fills your screen with one solid color at a time and asks you to look for any point that does not match the rest. It is the standard way to check a display, and the reason it works is that a fault invisible inside normal content becomes obvious against a uniform field. Run it when a screen is new and still returnable, before buying a used monitor or phone, and before a warranty period expires.

How to use it

1. Clean the screen first, so dust and smudges are not mistaken for pixel faults.
2. Click the panel, or press F, to go full screen. Do this in a dimly lit room.
3. Step through the colors: black, white, then red, green and blue in turn.
4. Look across the whole display on each color, corners included, from about arm's length. Press Esc when you are done.

About dead pixel test

Dead, stuck and hot pixels are three different faults

The terms get used interchangeably and mean different things. A dead pixel receives no power and stays black on every color, so it is only visible against a bright field: use white to find it. A stuck pixel is permanently lit in one color, usually red, green or blue, because one subpixel is jammed on; it shows most clearly against black. A hot pixel is stuck fully on and appears as a white dot on black. The distinction matters because it predicts what can be done: a stuck pixel is sometimes recoverable, a genuinely dead one is not.

Why each color finds something different

Every pixel is made of a red, a green and a blue subpixel, and the color displayed is a mixture of the three. A full red screen drives only the red subpixels, so a red subpixel that has failed shows as a dark dot which is invisible on any other color. Green and blue do the same for their own channels. White drives all three, which reveals fully dead pixels. Black switches everything off, which reveals anything stuck lit as well as backlight bleed. Skipping the primaries is how a single-channel fault gets missed.

What else the test reveals

On black in a dark room, look at the edges and corners for pale clouding. That is backlight bleed, light escaping around an imperfect panel seal, and it affects LCDs rather than OLEDs. Some is normal; a bright patch is not. Uneven grey patches across a black field are described as IPS glow or mura, depending on cause. And on white, a faint permanent ghost of an interface that used to be displayed is image retention or burn-in, which is a real risk on OLED panels that have shown the same static elements for a long time.

Can a stuck pixel be fixed?

Sometimes, and it is worth trying before writing a panel off. Rapidly cycling colors over the affected area for several minutes can occasionally free a subpixel that is jammed, which is why pixel-fixing videos exist and why they sometimes work. Gentle pressure on the spot with a soft cloth while the screen is on is another commonly suggested remedy, and it carries real risk of making things worse on a modern thin panel, so it is not something to reach for first. A dead pixel that receives no power cannot be recovered by any of this. If the display is under warranty, check the manufacturer's dead pixel policy before attempting anything.

How many faulty pixels a manufacturer will accept

Most manufacturers do not treat a single dead pixel as a defect. Policies are written against the ISO 9241-307 class system and typically allow a small number of faulty subpixels before a panel qualifies for replacement, with the exact threshold varying by brand, class and screen size. Some premium monitors ship with a zero bright pixel guarantee, which is a stronger promise and usually stated explicitly. Check the specific policy for your model rather than assuming, and if you find something during a return window, act inside it: consumer return rights are usually far easier to exercise than a warranty claim.