What each color reveals
| Color | Look for |
|---|---|
| White | Dead pixels (black dots), dust or debris under the panel, darker corners, yellow or pink tint in parts of the screen |
| Black | Stuck pixels (bright colored dots), backlight bleed at the edges, IPS glow in the corners |
| Red, green, blue | Subpixels that are stuck off (dark dot on one color only) or stuck on |
| 50% grey | Banding, "dirty screen effect" and uneven brightness, which show up best on mid-grey |
| Near black | Clouding and backlight bleed in a dark room, plus OLED near-black flicker or uneven tint |
How to run a proper test
- Clean the screen first with a dry microfiber cloth. Dust looks like a dead pixel. Use the white screen to spot it.
- Let the display warm up for 10–15 minutes and set brightness to your normal level.
- Turn off night mode (Night Shift, Night Light, f.lux) so colors are accurate.
- Darken the room for the black and near-black tests, since bleed is invisible in daylight.
- Scan in a grid. Look at the screen section by section from about 30 cm away. A magnifier or phone camera zoom helps.
Screen test FAQ
Press Start Screen Test, then click or press the arrow keys to cycle through white, black, red, green and blue. Look over the whole screen on each color. A dead pixel stays black on every color. A stuck pixel stays one bright color (often red, green or blue) even on black.
A dead pixel gets no power and shows as a black dot, most visible on the white screen. A stuck pixel has one or more subpixels always on, so it shows as a red, green, blue, cyan, magenta, yellow or white dot, most visible on the black screen. Stuck pixels can sometimes be revived. Dead pixels usually cannot.
In a dark room, set brightness to about 50–100% and show the near-black or black screen. Light leaking from the edges or corners is backlight bleed. Soft, cloudy patches in the middle are "clouding." OLED screens don't have backlight bleed because each pixel makes its own light.
The white screen shows dead pixels (dark dots), dust under the panel, uneven brightness (darker corners or bands), and color tint. If white looks noticeably yellow, pink or blue in parts of the screen, the panel has a uniformity problem.
Check the manufacturer's pixel policy (usually called ISO 9241-307 class or "zero bright dot" policy). Many brands only replace panels above a set number of defects, but some guarantee zero bright (stuck) pixels. Test within the return window, since retailers are often more generous than the manufacturer.