Display test
Screen Uniformity Test
A uniform screen looks like one gray, not a patch of lighter clouds or a corner that falls off. These five gray fields are for that look. They are not a brightness meter, and they do not name your panel type.
Click the field for the next one. It stays until you click. Full screen is only that field. Space runs them. Esc leaves.
What the uniformity test shows
Five gray steps
5%, 10%, 25%, 50%, and 75% gray. Clouding, a tint, and dark corners do not all show on the same step.
One field at a time
Full screen is only the gray. Click for the next step. The gray stays until you click, so a cloud is not moving while you look at it.
A look, not a meter
There is no nit reading, no percent score, and no photo upload. If a patch bothers you from your chair, that is the result that matters.
Separate from a bad pixel
A soft cloud is not a dead pixel. A single dot belongs on the dead pixel test. This page is for patches, edges, and a color cast across the panel.
Clouding, vignetting, and a tint
Uniformity is whether one gray looks like one gray. Vignetting is a corner or edge that is darker than the center. Clouding is a soft lighter patch, often called a dirty screen, and it usually shows on a dark or mid gray. A tint is one side that looks warmer or cooler than the other.
50% gray is the usual field for clouding. 5% and 10% show dark corners and light leaks that disappear on a brighter gray. 75% shows stains that white hides. 25% is the step in between, useful when mid gray looks fine and the dark steps look noisy.
LCD panels often look less even from the side. If a patch changes a lot when you move your head, look again from the center before you call it a defect. OLED panels have no backlight, so a dark corner on an OLED is not backlight bleed. Uneven gray can still show on either type. This page cannot tell you which panel you have.
A stuck pixel is a different fault. It is one sharp dot, not a cloud. Check that on the dead pixel test. A bright corner on black belongs on the backlight bleed test.
How to check gray uniformity
- Dim the room. Turn off lamps that reflect in the glass. A reflection looks like a bright patch and is not the panel.
- Sit straight on. Use the distance you sit at for work. Do not judge an LCD from a sharp angle.
- Start at 50% gray. Open full screen. This page starts on 50% gray. Look for clouds and a left-to-right tint. Click the gray for the next step.
- Step down, then up. Check 25%, 10%, and 5% for dark corners and dirty-screen patches. Then check 75% for stains. Pause on the worst field.
- Compare with the other tests. If the problem is one dot, switch to the dead pixel test. If it is a bright corner only on black, switch to the backlight bleed test.
Why use this screen uniformity test
Five grays, on purpose
5% and 10% are dark enough to show soft light patches. 25% and 50% are where a blotchy gray, sometimes called a dirty screen, usually shows. 75% shows a warm or cool tint that pure white can hide. One gray is a glance. The set is the test.
You judge from your chair
A uniformity problem matters if you can see it from the seat you use. Sit straight on, at that distance, and keep your head still for a moment. An LCD often looks worse from a sharp angle. Look again from the center before you call a patch a defect.
The page does not pretend to be a meter
These fields are flat colors, not nits, not a percent of uniformity, and not a lab grade. The browser cannot see the panel. You can. A number without a measurement would only sound precise.
Full screen stays empty
The gray has to reach the corners. Full screen is only the gray, and it stays until you click. A bar across the bottom would be the stripe you are trying not to judge.
What people use the uniformity test for
Clouds on a dark gray
Dim the room and hold 5% or 10% gray. A soft lighter patch that stays in the same place is the clouding people notice on an LCD. If it only appears when you lean, look again from the center. Bright corners on pure black belong on the backlight bleed test.
A blotchy 50% gray
Hold 50% gray for the patchy look that shows up on games, spreadsheets, and flat walls in photos. 25% is the step between that and the dark fields. The page does not scroll a pattern across the screen. If you need motion, use a video you already have and look again.
A tint on one side
On 75% gray, one half can look warmer or cooler than the other. Check it straight on. Viewing an LCD from the side changes the color of the whole field and can invent a tint. This page cannot name the panel type.
An OLED that is not perfectly even
OLED has no backlight, so a dark corner is not backlight bleed. Near-black gray can still look uneven, and a shape left by a static logo can show on a flat field. This page will not tell you whether that shape is temporary or permanent. Play moving pictures and look again later if you are unsure.
What a gray field does not measure
The browser does not know the panel’s brightness in nits, and it does not report a uniformity percentage. Two grays that look different on two monitors can still be the same hex on this page, because the panel and its settings are outside the page.
Windows, macOS, and the monitor’s own menu can change brightness, contrast, and a local-dimming mode. If the picture looks uneven, try the monitor’s standard mode before you blame the panel. This page cannot switch those settings for you.
A little falloff at the corners is common. A cloudy patch you can see from your normal seat on 50% gray is the one people return. The backlight bleed test and the monitor test cover the dark scene and the short combined pass.
Frequently asked questions
Which gray should I look at first?
50% gray. That is where clouding and a side-to-side tint usually show. Then check 5% and 10% for corners, and 75% for stains that white hides.
Is a darker corner always a defect?
No. Many panels are a little darker at the edge. Look from straight in front, at the size you use. If you only see it when you lean in, it may not matter at your desk.
What is a dirty screen?
A soft, cloudy patch that is lighter than the rest of a gray field. It is not dust on the glass, and it is not one dead pixel. Wiping the glass does not remove it.
Does this work on OLED?
You can look at the same grays. An OLED has no backlight, so a dark corner is not backlight bleed. The page still cannot tell LCD from OLED, and it cannot measure the panel.
Why did the patch move when I moved my head?
An LCD changes off-axis. Look again from the center. A patch that only appears when you stand to the side is often viewing angle, not a stain in the middle of the panel.
Can I get a number from this test?
No. There is no nit meter and no percent score. The result is what you can see on these five fields.
The controls covered the corner. How do I see it?
Full screen is only the gray. There is no bar on the field. Click for the next gray. Esc leaves.
Should I return the monitor for mild clouding?
That depends on the seller and on whether you notice it in real work, not only on a test gray. This page does not set that rule. Check it before the return window closes if the patch is obvious from your chair.
How do I run a screen uniformity test?
Dim the room enough that a lamp is not reflecting in the glass. Open full screen. This page starts at 50% gray. Click through 25%, 10%, 5%, and then 75%. Leave the worst field up and look at it.
What is the dirty screen effect?
It is a blotchy or banded gray that stays in the same place, easiest to see around 25% and 50% gray. It is not a single stuck pixel. Use the dead pixel test for one dot. This page only shows the flat grays.
Which gray shows clouding?
Look at 5% and 10% gray in a dim room for soft lighter patches, and at 50% gray for a darker corner or an overall uneven field. A patch that moves when you move your head is often the viewing angle or a reflection, not a fixed cloud.
Does this measure nits or a uniformity percentage?
No. The colors are fixed hex values. The page does not read the panel, does not report candelas, and does not give a pass or fail score. Your eyes at your normal seat are the measurement.
Can a uniformity test see OLED burn-in?
A flat gray can show a leftover shape. The page cannot tell a temporary retained image from permanent wear, and it will not declare a panel burned in. If the shape fades after moving content, it was not a verdict.
Why is there no grid and no panning pattern?
The job of this page is the flat field. A grid and a moving stripe are extra tools, and they are not here. If a still gray looks even and a moving picture does not, trust the picture you actually watch, not a feature this page does not have.
