Dead Pixel Test

How to check your screen

1. Clean the screen first with a soft, dry cloth. Dust looks a lot like a bad pixel.
2. Press Start full-screen test. The screen fills with black.
3. Look slowly across the whole screen, corner to corner. Then click, tap or press the right arrow for the next color.
4. Go through black, white, red, green, blue, gray and the gradient. Press Esc or the Exit button when you are done.

The mouse pointer hides after two seconds without movement, and the hint at the bottom fades away, so nothing hides a pixel. Left arrow goes back one color.

What to look for

• On black: a bright dot of any color is a stuck pixel (or a fully lit one).
• On white: a black dot is a dead pixel. A colored dot is a pixel with one part missing.
• On red, green and blue: a dot in another color shows which part of the pixel misbehaves.
• On gray and the gradient: look for patches, banding, or areas that look darker or lighter than the rest.

Each pixel is made of three tiny parts: red, green and blue. A dead pixel has no light at all. A stuck pixel has one or two parts that stay on, so it shows up as a colored dot, most clearly on black.

Other things you may notice

Backlight bleed

Lighter patches near the edges or corners on a black screen, most visible in a dark room. Many LCD screens show a little. It is not a pixel fault.

Uneven brightness

On white or gray, some areas may look slightly dimmer. Small differences are normal. Large blotches can be a sign of a panel problem.

Image retention

A faint ghost of a previous picture, often visible on gray. On many screens it fades after a while showing other content.

Using the stuck pixel fixer

The fixer shows a small square that flashes red, green, blue, white and black very quickly. The idea is that rapid changes may help a stuck part of a pixel start working again. It works for some stuck pixels and does nothing for dead ones.

Read the warning first. Do not use the fixer if you have photosensitive epilepsy or are sensitive to flashing light. It only starts after you tick the box and press Start, and it always stops with the Stop button or the Esc key.

1. Find the stuck pixel with the color test and remember where it is.
2. Tick the box, choose a speed and size, and press Start fixer.
3. Drag the square over the pixel. Look away from it while it runs.
4. Leave it for several minutes, then stop it and check again with the color test.

New screen with a bad pixel?

Run this test as soon as you get a new monitor, laptop or phone, while you can still return it. Pixel policies differ between brands and stores, so check your warranty for how many bad pixels are accepted.

Testing a new setup? Try the webcam test and the speaker test too.