Screen uniformity test

Flat fields of gray, white and color, held still, so any patch that is brighter, darker or tinted has nowhere to hide. This is the test that explains why a football pitch looks smeared with grime while a normal film looks fine. Made to run on the television itself, in the room where you actually watch.

This test needs JavaScript to run. Everything below still explains what to look for and what a bad result means, so the page is useful either way.

Eight flat fields

Four levels of gray, then white, red, green and blue. Step through with the arrow keys and let your eyes settle on each one. Look at the whole panel from your normal seat, not up close: Uniformity faults are a viewing-distance problem, not a nose-to-glass one.

Start the flat fields Start with auto cycle

Dim the room first. In daylight a panel looks far more even than it is.

How to read it

Every field looks flat and even

Good uniformity. Some falloff at the very corners is normal on any LCD.

✓ Even

Faint vertical bands or a grubby film on the gray fields

The dirty screen effect. Most visible on panning shots of grass or ice, which is why sport shows it and films do not.

! DSE

Lighter patches or streaks on the darkest fields

Backlight clouding. An LCD backlight fault, covered in the clouding guide.

! Clouding

Corners noticeably dimmer or warmer than the middle

Vignetting or tint drift. Mild is normal, strong is a panel-quality issue worth a return.

! Uneven

A large blotch that keeps its shape on every field

Pressure damage or a failing panel, not uniformity. Treat it as a warranty case.

✗ Panel

Quick answer

A screen uniformity test shows flat, single-tone fields so uneven areas of a panel become visible. Mid and dark grays reveal the dirty screen effect and backlight clouding; white reveals tint and dimmer corners. Every LCD is uneven to some degree, because the backlight and the layers above it are never perfectly flat, so the question is not whether you can find unevenness but whether you can see it in normal viewing. If bands only appear on the test fields and never during a match, the panel is fine.

What did you see?

Pick the closest match and we take you straight to what causes it and what fixes it.

Bands or grime on grass during sport Lighter patches on the darkest fields Corners dimmer or warmer than the middle A hard-edged blotch that keeps its shape Ghosted logos on an OLED

Next test Backlight Bleed Test Pure black fields expose light leaking in from the edges.

Or jump straight to another test:

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What this test can and cannot tell you

Uniformity is the most subjective thing on this site, so here is exactly where the line sits.

Showing unevenness

Reliable. Flat fields are how panels are checked in the factory too. If your screen has visible bands, blotches or tint zones, these fields will show them.

Putting a number on it

Not possible here. A real uniformity figure needs a meter measuring many points on the panel. A browser cannot see your screen, so this test gives you your own eyes on a fair pattern, nothing more.

Telling DSE from clouding

By which field shows it. The dirty screen effect appears on mid grays as bands or a grubby film. Clouding appears on near-black as lighter patches. Both can exist on the same set.

Whether it is bad enough to return

Your call, and the test is only half of it. Manufacturers rarely publish uniformity limits, so the honest test is content: If you can see it during a match or a dark film from your normal seat, it is a fault worth acting on. If it only shows on this page, it is the panel lottery, not a defect.

Fixing it

Mostly no. Unevenness is physical, built into the panel and its backlight. Lowering the backlight and switching off local dimming can make it less obvious, but nothing removes it.

Knowing what you are looking at

Dirty screen effect

Faint vertical or horizontal bands, like a cloth was dragged across the panel. Invisible in most content and glaring on a panning shot of a pitch, because your eye tracks the motion while the bands stay still.

Clouding

Lighter grey patches on a dark field, coming from an unevenly pressed or lit backlight. An LCD problem only; the clouding guide covers what reduces it.

Vignetting and tint zones

Corners that sit dimmer, warmer or cooler than the centre. Very common, mild on a good panel, and most obvious on the full white field.

Why OLED differs

OLED has no backlight, so it has no clouding and usually far better uniformity. What it can show instead is uneven wear from long static content, which is burn-in, not a uniformity fault.

Questions people ask

What is the dirty screen effect on a TV?

Faint bands or a grubby-looking film across the picture, caused by small unevenness in the panel's layers. It is called dirty screen effect because it looks like the screen needs a wipe, but cleaning changes nothing. It shows most on wide, evenly coloured panning shots, which is why football, hockey and snooker expose it while normal drama hides it.

Why does my TV look patchy during football?

Because a pitch is a large, evenly coloured surface that moves. Your eye follows the players, so any fixed unevenness in the panel appears to slide across the grass as dirt or banding. Run the mid gray fields on this page: If you see the same bands there, that is the dirty screen effect and not the broadcast.

Is uneven screen brightness normal?

Some is, on every LCD. The backlight, the diffuser and the panel layers are never perfectly flat, and corners are usually a little dimmer than the middle. What is not normal is a strong patch, a hard-edged blotch or banding you can see in ordinary viewing rather than only on a test field.

Can the dirty screen effect be fixed?

No, not by any setting or software. It is physical. You can make it less noticeable by lowering the backlight, turning off aggressive sharpening and noise reduction, and sitting a little further back. If it is bad enough to spoil sport, the real fix is a replacement panel while the set is still within its return window or warranty.

Do OLED TVs have uniformity problems?

Far fewer. With no backlight there is no clouding and no bleed, and blacks stay even. OLEDs can show faint vertical banding on mid grays too, though usually milder, and their own long-term risk is uneven wear from static logos, which the burn-in test covers.

How do I test screen uniformity properly?

Dim the room, set the TV to a normal picture mode rather than a shop demo mode, and show flat fields full screen: A few levels of gray first, then white and the primary colors. Look from your usual seat and give your eyes a few seconds on each field. Judging up close, or in daylight, gives a misleading answer in both directions.