What should a good screen uniformity test look like?

The field should appear broadly even from your normal viewing position. Small edge differences can be common, especially on large LCD panels. Fixed bands, obvious blotches, or a strong warm-to-cool shift matter more when they remain visible in normal content.

Why does 50% gray reveal dirty-screen effect?

Middle gray exposes both darker and brighter deviations without pushing the panel to either extreme. Fixed mottling and vertical bands often become easier to see against this even mid-tone field.

Can this test measure brightness uniformity as a percentage?

No. The page supplies known RGB fields and a visual comparison grid. Calculating luminance deviation requires readings from a colorimeter or photometer at the center and surrounding screen zones.

Is a warmer corner a color-accuracy problem?

It is a color-uniformity observation. Color accuracy describes how closely measured colors match a reference target, while uniformity describes how consistent the same color remains across the panel.

Should local dimming be enabled?

Test first with the settings used for everyday content. On a Mini-LED display, repeat key patterns with local dimming off when the monitor allows it. That comparison helps separate panel shading from zone-dimming behavior.

Can a camera prove a uniformity defect?

A photo can document location and severity, but automatic exposure, white balance, lens shading, reflections, and viewing angle can exaggerate the result. Lock exposure when possible and include normal content alongside the test pattern.

Is dirty-screen effect fixable?

Picture settings may reduce how visible it is, though fixed panel variation usually cannot be repaired through a webpage. Use built-in panel care only as the manufacturer directs, then contact the seller when the issue disrupts normal viewing.

Screen Uniformity Test

Screen uniformity test reveals fixed brightness variation, dirty-screen effect, banding, and uneven color across a monitor, TV, laptop, tablet, or phone.

Ten patterns plus custom color
Visual test runs locally
No camera, upload, or account

Uniformity patterns and observation map

Start at 50% gray, inspect fullscreen, then record anything that remains fixed in place

50% gray · 0 marked

50% gray

General brightness and gray uniformity

Test pattern

Custom color#9A8FB0

Comparison grid

Marked observations

None yet

Use the arrow keys to change patterns. Inspect first, then enable marking so the grid does not influence what you see.

This is a visual inspection. The browser cannot measure luminance, white point, Delta E, or a manufacturer's tolerance without a colorimeter.

How to use the screen uniformity test

Leave the display at its everyday brightness first. A test performed only at maximum brightness can expose behavior you never encounter, while a setting buried near minimum may make every small variation look serious. Keep the room lighting steady and sit where you normally work or watch.

1
Prepare the display
Clean the panel, let it reach normal working temperature, and keep the brightness and picture mode you use every day.
2
Start with 50% gray
Open the gray field fullscreen. Sit at your normal distance and look for fixed bands, blotches, dim edges, or a center that differs from its surroundings.
3
Compare dark and bright gray
Use 5% and 10% gray for near-black behavior, then 75% gray and white for bright-field shading and color-temperature shifts.
4
Check color fields
Cycle through red, green, and blue. A region that repeatedly looks weaker or tinted across several colors deserves a second look.
5
Confirm with normal content
Play the sports, games, documents, or editing work that made you suspicious. Record an issue only when it remains distracting in ordinary use.

Gray patterns for dirty-screen effect and banding

Fifty-percent gray is the practical starting point. It places the whole panel in a mid-tone state where both lighter and darker deviations remain visible. In my experience with browser test surfaces, jumping straight from black to white makes it harder to describe a faint center blotch; middle gray gives the eye somewhere calmer to settle.

Pattern	Inspect for	Where it matters	Second check
5% and 10% gray	Near-black bands and dark patches	OLED films, games, and shadow detail	A familiar dark scene
25% gray	Clouding and broad mottling	Dim interfaces and panning shots	Panning gray pattern
50% gray	Dirty-screen effect and vignetting	Sports, documents, and creative work	3 × 3 comparison grid
75% and white	Dim edges and color-temperature shifts	Web pages, snow, and bright editing canvases	Normal hardware brightness

Screen brightness test across nine zones

Turn on the 3 × 3 grid after inspecting the clean field. Compare each corner and edge with the center, but keep your head still. IPS glow and viewing-angle color shift can change when you lean even a few inches sideways, which is easy to mistake for a fixed panel defect.

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Datacolor's instrument workflow measures a center point and eight surrounding areas at several brightness levels. Our map follows the same screen geography for observations, though only a colorimeter can supply luminance and Delta E values. Mark regions after viewing the plain field so the lines do not steer your judgment.

Monitor color test for uneven tint

Red, green, and blue fields help reveal a region that repeatedly looks weaker, murkier, or shifted in hue. White is useful for a warm corner or a cool strip. Choose Custom color when the problem appears in a particular application and you know the approximate color that triggers it.

Consistency

The same RGB field should remain broadly similar from the center toward the edges when viewed straight on.

Brightness

A dim region that persists across gray and several colors is stronger evidence than a difference visible on one field.

Viewing angle

Move slightly after the first inspection. A patch that changes with your position may come from panel angle behavior or glow.

Can a browser test color accuracy of a monitor?

A browser can send defined RGB values and help you compare one part of the screen with another. It cannot see the light coming back from the panel. Objective color accuracy requires an instrument, a known reference, controlled measurement conditions, and software that calculates values such as Delta E.

This visual test can reveal: Fixed bands, blotches, edge shading, obvious tint changes, and patterns that remain tied to the panel during movement.
An instrument can measure: Luminance, contrast, white point, color error, gamma, and numerical variation between the center and surrounding zones.

Moving gray test for a TV or monitor

The Panning pattern moves a gentle gray gradient across the display. Watch for a shadow or vertical stripe that stays anchored while the gradient travels behind it. For a TV browser that is awkward to control, the video below provides a longer 50% gray field that can be opened through the YouTube app.

Alternate moving test from Tech Steve. Use moderate brightness, watch from your normal seat, and stop once you have enough information.

Screen quality test for LCD, OLED, and Mini-LED

LCD

Look for vignetting, clouding, backlight bands, and angle-dependent IPS glow. Repeat black-screen leakage separately with the backlight bleed test.

OLED

Near-black gray can reveal vertical banding and tint. Avoid leaving static patterns open longer than needed at high brightness.

Mini-LED

Local dimming can change broad fields and zone boundaries. Compare the normal mode with local dimming disabled when that option exists.

Documenting a monitor display test

Note the pattern, brightness setting, picture mode, room lighting, viewing distance, and whether HDR or local dimming was active. Photograph the whole display square-on. Then capture normal content that shows the same problem. A close-up of one bright corner without context can make a mild issue look enormous.

Record the affected zone and pattern.

Lock exposure and white balance when possible.

Confirm the same variation in ordinary content.

Related display checks

A uniformity field can expose a dark pixel, though a complete dead-pixel test cycles patterns for that specific job. Use the white screen test for dust and bright-field inspection. The white brightness screen is intended as an adjustable light source.

FAQ

What should a good screen uniformity test look like?: The field should appear broadly even from your normal viewing position. Small edge differences can be common, especially on large LCD panels. Fixed bands, obvious blotches, or a strong warm-to-cool shift matter more when they remain visible in normal content.
Why does 50% gray reveal dirty-screen effect?: Middle gray exposes both darker and brighter deviations without pushing the panel to either extreme. Fixed mottling and vertical bands often become easier to see against this even mid-tone field.
Can this test measure brightness uniformity as a percentage?: No. The page supplies known RGB fields and a visual comparison grid. Calculating luminance deviation requires readings from a colorimeter or photometer at the center and surrounding screen zones.
Is a warmer corner a color-accuracy problem?: It is a color-uniformity observation. Color accuracy describes how closely measured colors match a reference target, while uniformity describes how consistent the same color remains across the panel.
Should local dimming be enabled?: Test first with the settings used for everyday content. On a Mini-LED display, repeat key patterns with local dimming off when the monitor allows it. That comparison helps separate panel shading from zone-dimming behavior.
Can a camera prove a uniformity defect?: A photo can document location and severity, but automatic exposure, white balance, lens shading, reflections, and viewing angle can exaggerate the result. Lock exposure when possible and include normal content alongside the test pattern.
Is dirty-screen effect fixable?: Picture settings may reduce how visible it is, though fixed panel variation usually cannot be repaired through a webpage. Use built-in panel care only as the manufacturer directs, then contact the seller when the issue disrupts normal viewing.

Sources

Links go to official browser docs or primary references when available.