Dead Pixel Test

Dead, stuck, and the difference

Both look like a wrong-coloured dot, and they are different faults with different prospects.

• A dead pixel receives no power. It stays black on every colour, including white. Nothing fixes this — the subpixel is not working.
• A stuck pixel is permanently on in one or more colours. It shows as a bright red, green, blue or white dot, and it changes appearance between test colours. These sometimes recover.

That is what the colour cycle is for. A dot that is black on white and black on red is dead. A dot that is bright on black and invisible on white is stuck.

Why each colour is in the set

• Black reveals stuck pixels — anything lit is obvious.
• White reveals dead pixels and dust.
• Red, green and blue test each subpixel separately, since every pixel is made of all three.
• Cyan, magenta and yellow test them in pairs, which catches a subpixel that is weak rather than failed.
• Mid grey shows backlight unevenness and clouding, which neither black nor white makes obvious.

How to use it

1. Clean the screen first. A surprising proportion of suspected dead pixels are dust.
2. Go full screen and let your eyes adjust for a few seconds on each colour.
3. Click or press an arrow key for the next colour, or turn on automatic cycling and simply watch.
4. Look across the whole panel, including the corners, where backlight problems usually start.
5. Press Escape to leave.

Common uses and tips

Before you buy

This is the single best use of the tool. Checking a screen in the shop, or within the return window of a new one, takes a minute and is far easier than arguing later. Manufacturers publish dead-pixel policies that usually allow a few faults before a panel counts as defective, so knowing what you have early matters.

If you find a stuck pixel

• Leave it a few days. Some resolve on their own.
• Rapid colour cycling sometimes unsticks one. Automatic cycling here is slow by design, but dedicated tools flash faster.
• Gentle pressure with a soft cloth over the spot, screen off, occasionally works. Firm pressure damages the panel, so this is a last resort rather than a first one.
• Dead pixels do not recover. If it is black on white, warranty is the only route.

Other things this finds

• Backlight bleed — lighter patches at the edges on the black screen, common on LCDs and not usually a fault.
• Clouding — uneven patches on mid grey.
• Burn-in on OLED panels — a faint ghost of a previously static image, most visible on mid grey.
• Dust under the glass, which looks like a dead pixel and is not.

Questions people ask

What is the difference between a dead and a stuck pixel?

A dead pixel is black on every colour because it gets no power. A stuck pixel is permanently lit in one or more colours, so it changes appearance between test screens. Stuck pixels sometimes recover; dead ones do not.

Can a stuck pixel be fixed?

Sometimes. Leaving it, rapid colour cycling, or very gentle pressure with the screen off all occasionally work. Firm pressure damages the panel.

How many dead pixels before a warranty claim?

It varies by manufacturer and panel size. Most publish a policy allowing a small number before a panel counts as defective, so check the specific terms.

What is backlight bleed?

Light leaking at the edges of an LCD, visible as lighter patches on a black screen. Common, and usually not considered a fault unless severe.

Why is a mid-grey screen included?

It shows backlight unevenness, clouding and OLED burn-in, none of which are obvious on pure black or white.