Monitor uniformity test
Step through full-screen greys, from very dark to light. On a uniform panel each grey looks the same across the whole screen; patches, dark corners or vertical bands show where the panel is uneven.
Full screen opens on black. Click, press Space or → for the next colour, ← for the previous one. Esc exits.
Or open a single colour:
How to check uniformity
- Let the screen warm up for a few minutes and set your normal brightness.
- Dim the room lights so reflections do not mislead you.
- Press Start uniformity test and step through the greys with a click or →.
- Look at the whole screen from your usual distance, then from a little further away. Do not judge from an angle.
What each grey shows
- 5–10% grey: clouding and backlight unevenness on LCDs; near-black uniformity and banding on OLEDs. For a full black check see the black screen.
- 20–30% grey: dirty screen effect — blotches or vertical bands that become visible when the image moves across them, common on large TVs.
- 50% grey: colour tint differences between areas (one side pinker or greener).
- 75% grey and white: vignetting (darker corners or edges) and overall tint.
What is normal
No panel is perfectly uniform. Slight vignetting and mild variation in dark greys are common, especially on large or curved screens. A defect is worth acting on when it is visible in normal content — for example bands you notice during camera pans or dark scenes. Phone cameras exaggerate uniformity problems, so judge with your eyes.
Questions
What is the dirty screen effect (DSE)?
Uneven patches or bands on a flat grey that look like a dirty window. It is most noticeable when uniform areas move across the screen, such as a football pitch or sky in a panning shot.
Can the uniformity be fixed?
Some monitors have a uniformity compensation option in their menu. Otherwise it is a property of the panel; strong cases may qualify for an exchange under the seller's or manufacturer's policy.
Related tests
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- Backlight bleed testDark full-screen fields to tell backlight bleed, IPS glow and clouding apart.
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- Gradient testGrey, red, green and blue ramps from 0 to 255 to spot colour banding, with 16–256 step references.
- Screen colour testFull-screen solid colours: red, green, blue, yellow, purple, pink and any custom colour.
- Touch screen testDraw over the whole screen to find dead zones and check multi-touch.
- Ghosting testMoving objects at three labelled speeds on four backgrounds to compare ghosting, smearing and overshoot.
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- Frame skipping testA grid that lights one cell per frame; a long-exposure photo shows skipped frames as gaps.
- White screenA plain white full-screen page for checking, cleaning or lighting.
- Black screenA pure black full-screen page to find bright pixels and backlight bleed.
- Red screenA full-screen red light in four brightness levels, from pure red to very dim.
- Pink screenA full-screen pink light in soft shades, for selfies, video calls and backgrounds.