Dead Pixel Test

How to run a dead pixel test

Dim the room, wipe the screen, press Start full screen and scan each color slowly, one area at a time. Click, press Space or → for the next color, ← for the previous one, and Esc to exit. Clicking a color button starts from that color.

A single pixel is tiny, so check the screen in quarters from close up. If you find a dot, wipe the screen again; one that stays put and only shows on certain colors is a pixel, not dust.

The result shows how many of the 7 colors you viewed, plus Screen resolution, Scale and Physical pixels. A 1920 × 1080 laptop set to 125% scaling in Windows reports a resolution of 1536 × 864 at 1.25× scale, so physical pixels work out to 1920 × 1080. At the end, pick No dead pixels or Found dead pixels based on what you saw.

Dead pixel vs stuck pixel

A dead pixel is always dark; a stuck pixel is always lit, usually in one color such as red, green or blue. A hot pixel is one stuck on bright white.

Each pixel is made of three subpixels: red, green and blue. When all three stay off, you see a black dot on the white screen. When one stays on, you see a colored dot on the black screen. A single dead subpixel only stands out on its own color, which is why the test shows red, green and blue separately.

Write down where the dot is (for example, how far from the top-left corner), whether it is bright or dark, and which color showed it. Monitor makers often count bright and dark dots separately in their pixel policies, and a photo plus this note makes a support request faster.

Backlight bleed test: bleed vs IPS glow

In a dark room on the dark gray screen, light that stays in the same place and shape when you move your head is backlight bleed. Light that changes as you change the viewing angle is IPS glow.

Backlight bleed is light leaking around the edge of an LCD panel, so it sits at fixed spots on the edges or corners. IPS glow comes from viewing an IPS panel at an angle and fades when you sit back and look straight on. Phone cameras exaggerate bright areas on a dark screen, so judge by eye.

Use the gray screen for mura (cloudy darker or lighter patches) and, on an OLED, for burn-in.

Testing a new monitor and dead pixel policies

Test a new monitor the day it arrives, while you can still return or exchange it. Return windows and dead pixel policies differ by manufacturer, retailer and model, so read both before you buy or as soon as the monitor arrives.

The details that matter are whether bright and dark dots are counted separately, whether dots in the center of the screen count differently from dots near the edge, and how long you have to report them.

Can you fix a stuck pixel?

Sometimes. A stuck pixel can recover after running a rapidly changing color pattern for a while, but there is no guarantee, and a dead pixel does not come back this way. This test only shows still, solid colors; it never flashes.

Fast-flashing screens can be harmful to people sensitive to flashing light. Pressing on the panel with a finger or cloth is often suggested, but pressure can damage the panel further. If you are still within the return or warranty period, ask for an exchange first.

Motion blur or ghosting behind moving objects is a different problem. It does not show on a still screen and depends on panel response time and refresh rate.