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Screen Uniformity Test

Free online screen uniformity test for monitors, laptops, TVs and phones. Show flat grey full screen, spot dark corners, clouding, tint and banding, and rate each area of the panel.

3 minTest time
8Test patterns
FreeNo sign-up
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50% Grey1 / 8-
50% Grey1 / 8

What Is Screen Uniformity?

Screen uniformity is how evenly a display shows the same brightness and color across its whole surface. On a perfectly uniform screen, a flat grey looks like one shade from corner to corner. Real screens vary a little, and a uniformity test shows you by how much.

An LCD screen lights the picture with a backlight, and that light has to spread evenly across the whole panel through diffuser sheets. Edge-lit screens, which light the panel from the sides, are harder to make even than screens with LEDs behind the full panel. Pressure from the frame and small differences in the layers can leave some areas brighter, darker or slightly tinted.

OLED screens have no backlight, so they are usually very even, but each pixel is driven separately, and on very dark greys small differences can show as faint bands or patches. Uniformity matters most for photo and video editing, where you need to trust that a color looks the same everywhere, and in films and sports, where a flat sky or pitch fills the screen.

Dark Corners

Brightness falls off toward the corners and edges, often called vignetting. Most common on LCDs.

Clouding

Soft bright and dark patches spread across the panel, most visible on dark grey.

Color Tint

One side looks slightly pink, green or yellow compared with the rest, easiest to see on light grey or white.

How To Test Screen Uniformity In 6 Steps

Uniformity is about comparing areas, so the room, your position and a warm screen all matter.

  1. Warm Up The Screen

    Use it normally for about 30 minutes first. Uniformity can change as the panel reaches its working temperature.

  2. Set Brightness And Room

    Use your normal brightness, turn off auto-brightness and dim the room to avoid reflections.

  3. Sit Straight On

    Center your eyes on the screen at your usual distance. On large screens, step back a little too.

  4. Start With 50% Grey

    Open it full screen and compare each corner and edge with the center. Then check 25%, 10% and 5% grey.

  5. Check Tint And Motion

    Use 75% grey and white for color tint, and the Pan test for blotches that stay still as lines move.

  6. Rate And Save

    Turn on Rate, tap each uneven zone, tick the issue types and download the report.

Common Screen Uniformity Problems

Each problem shows best on a different pattern. Use this table to know what you are looking at and where to look for it.

ProblemHow it looksBest patternCauseScreens
Dark cornersEdges dimmer than the center50% greyBacklight spread, viewing angleMostly LCD
CloudingSoft bright and dark patches5% and 10% greyUneven backlight and diffuserEdge-lit LCD
Color tintPink, green or yellow areas75% grey and whitePanel and backlight variationLCD and OLED
BandingFaint vertical or horizontal stripes5% and 10% greyPanel driving variationOLED and LCD
Dirty screen effectBlotches that stay still in motionPan testPanel uniformityMostly large TVs
Backlight bleedGlow at edges on blackPure blackLight leaking past the frameLCD

Backlight bleed is checked on pure black rather than grey. Use the Backlight Bleed Test for it.

How Much Uniformity Variation Is Normal?

No screen is perfectly even. These four levels match the ratings in the tool.

None

The grey looks like one shade everywhere, even when you look for differences.

Excellent panel

Slight

Small differences you only notice on a test pattern when you search for them. Normal for most screens.

Usually within normal

Noticeable

Visible right away on grey, and sometimes on web pages with light backgrounds or flat skies in films.

Check your return window

Severe

Uneven areas you notice in everyday use, in documents, games and films at normal brightness.

Exchange or claim

Review sites measure uniformity with a colorimeter across a grid of points. By eye, judge at your normal brightness and seat: what matters is whether you notice it in real use.

Why Uniformity Can Look Worse Than It Is

Some uneven patches come from how you look at the screen, not from the panel itself. Rule these out before you decide.

Viewing Angle

On large and wide screens, you see the edges at a sharper angle than the center, which can make them look darker or shifted in color. Step back and check again.

Viewing angle test

Camera Exposure

Phone cameras boost exposure and contrast, and many lenses darken the corners of a photo. A photo can show vignetting your eyes do not see.

Room Light And Reflections

A window or lamp reflecting in part of the screen makes that area look washed out. Dim the room and check for reflections.

A Cold Screen

Right after switching on, a panel can look less even than it will once warm. Test after about 30 minutes of use.

How To Improve Screen Uniformity

Uniformity is set mostly by how the panel was built, but a few settings and choices help.

Turn On Uniformity Compensation

Many professional monitors have a uniformity compensation mode, set at the factory, that evens out the panel. It lowers maximum brightness and contrast.

Calibrate For Color

Calibration fixes the overall white point and gamma, which can make tint less obvious. It does not even out individual zones.

Color accuracy test

Exchange In The Return Window

Uniformity varies from unit to unit of the same model, so a replacement can be noticeably better. Test the new one the same way.

Do Not Press Or Loosen The Panel

Pressing the panel or loosening screws to move patches around can crack it, create new marks and void the warranty.

Uniformity On Monitors, Laptops, TVs And Phones

The test is the same everywhere, but each device has its own typical weak spots.

Monitors

Wide and curved monitors often show darker or tinted edges. Check from your seat, then from a step back.

Monitor test

Laptops

Thin lids can leave patches near the hinge or where the lid flexes. Test with the lid at your usual angle.

Laptop test

TVs

Large TVs are where the dirty screen effect and clouding show most. Use the Pan test in the TV browser.

TV test

Phones

OLED phones can show a slight tint or faint bands on dark grey at low brightness. Try the 5% grey pattern.

Phone test

Screen Uniformity Test FAQ

Answers to what people ask most when a screen looks uneven.

What is a screen uniformity test?

A screen uniformity test fills your display with one flat shade of grey or white so you can see whether brightness and color look the same in every area. Dark corners, bright patches, tinted areas and stripes all stand out against an even field.

How do I test my monitor for uniformity?

Let the screen warm up, set your usual brightness and dim the room. Open 50% grey full screen, sit straight on at your normal distance and compare the corners and edges with the center. Repeat on the darker greys, white and the pan test.

What is good screen uniformity?

On good uniformity, a flat grey looks like one even shade from corner to corner with no visible tint changes. Small differences that you have to search for are normal on every screen, especially LCDs.

Why are the corners of my monitor darker?

Darker corners, called vignetting, usually come from how the backlight spreads light across an LCD. On large or curved screens, the corners are also seen at a sharper angle, which makes them look darker. Step back and look again before judging.

What is the dirty screen effect?

The dirty screen effect is a set of faint blotches or vertical bands that stay fixed on the panel while the picture moves. It is easiest to see when the camera pans across a football pitch, ice rink or sky, and it is most common on large TVs.

Can calibration fix screen uniformity?

Standard calibration corrects the overall color and brightness of the whole screen, not differences between areas. Only monitors with a uniformity compensation feature, set at the factory, can even out individual zones.

What is uniformity compensation?

Uniformity compensation is a monitor setting that dims brighter areas of the panel to match darker ones, using measurements taken at the factory. It makes the screen more even but lowers maximum brightness and contrast. It is found on many professional and some prosumer monitors.

Is poor uniformity a reason to return a monitor?

If uneven areas are clearly visible in everyday use, such as web pages, documents or films at your normal brightness, it is reasonable to ask for an exchange within the return window. Faint differences that only show on a test pattern are common.

Do OLED screens have better uniformity?

OLED screens are usually very even on black and mid grey, because there is no backlight to spread unevenly. They can still show faint bands or slight tint on very dark greys, which the 5% and 10% grey patterns help reveal.

Does screen uniformity change over time?

It can. LCD backlights age slowly and unevenly, and OLED screens can wear unevenly where static images sit, which is burn-in. Testing when the screen is new gives you a baseline to compare against later.

Ready To Check Your Screen Uniformity?

Open 50% grey full screen and compare every corner with the center.