Brightness patches
On 20–50% gray, note any soft, cloudy patches or blotches (mura) that make parts of the field read lighter or darker than their surroundings.
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Screen Uniformity Test
DISPLAY DIAGNOSTICFill your screen with exact grayscale levels, black, white and pure colors, then inspect brightness consistency, color consistency, visible patches, vignetting and DSE across the whole panel.
LevelsGrayscaleColorsRGB · WhiteChecksCloud · Tint
RUNS LOCALLY
READYCurrent Field
Pattern 50% GRAYLevel 50%Mode STANDARDTime 0s
Field: 50% GrayLevel: 50%State: READY
TEST 07 / 13Next in 5.0s
Grayscale levels — neutral gray rgb(v,v,v)
Brightness steps — white base
Values represent browser-rendered surface levels, not monitor hardware luminance in nits.
Solid colors — pure channel values
Dark levels — near-black grays
Inspect dark-level uniformity and clouding. A dark room makes faint variations easier to see.
Custom color
Automatically steps through: Black, 1%, 2%, 5%, 10%, 20%, 50%, 75%, 100% White, Red, Green, Blue, Gray.
Time per pattern
While a field is displayed, grade each zone by eye. Nothing here is measured automatically — these are your suspected observations.
01 Top Left
02 Top Center
03 Top Right
04 Middle Left
05 Center
06 Middle Right
07 Bottom Left
08 Bottom Center
09 Bottom Right
How to Test Screen Uniformity
- 1Dim the room. Low ambient light reveals clouding, backlight bleed and near-black shading that bright rooms hide.
- 2Warm the panel for 30 minutes. Backlights drift while cold, so an unwarmed panel can look less uniform than it really is.
- 3View perpendicular at arm's length. Facing each zone head-on avoids angle-driven brightness and color shifts, especially at corners.
- 4Step through the gray levels. Compare center, edges and corners from near-black to white — or run the 13-pattern sequence and record observations per zone.
What to Look For
Vignetting & glow
On white, corners may look dimmer (vignetting). On near-black, corners may glow (backlight bleed or IPS glow). Shift your head: glow moves, fixed bleed does not.
Color consistency
On white and light gray, compare quadrants for temperature shifts — one side looking warm or the other cool. Check each pure primary for patches of its own.
DSE (distinct shading effect)
A symmetric wash across one side or corner, most visible on mid grays. Minor, slowly varying shading is common; sharp or growing patches are worth tracking over repeat visits.
Screen Uniformity Test Guide
Learn what screen uniformity means, how to test a monitor for uneven brightness and color, how to inspect dark and gray screens, and how to identify possible clouding or panel variation.
01
What Is Screen Uniformity?
Screen uniformity measures how consistently a display reproduces luminance and color temperature across its entire surface area without localized hotspots or dark corners.
02
What Is Brightness Uniformity?
Brightness uniformity refers to the balance of light distribution from the backlight unit or OLED array. Edge-lit monitors often show slight light drop-off near the borders.
03
What Is Color Uniformity?
Color uniformity describes whether white and gray fields look visually neutral everywhere, without shifts toward green, pink, or yellow across different quadrants.
04
How to Test Screen Uniformity
Open a full-screen 50% gray or white pattern in fullscreen mode. Dim your room lighting and scan systematically from center to corners for dark patches or color tinting.
05
How to Test a White Screen
A 100% white screen reveals color temperature shifts, vignetting, and corner darkening that can distract during document reading, web browsing, and photo grading.
06
How to Test a Gray Screen
A 20% to 50% gray field is the most demanding test for panel uniformity, exposing subtle luminance blotches (mura) and vertical banding that pure white masks.
07
How to Test a Black Screen
Black and 1% near-black patterns reveal backlight bleed, corner light pinching, and IPS glow that degrade cinematic contrast and dark gaming scenes.
08
How to Check Screen Corners
Inspect all four corners directly. Move your head slightly to check whether corner darkness is caused by viewing angle vignetting or physical diffuser falloff.
09
How to Check Screen Edges
Look along the top, bottom, and side bezels. Uneven bezel frame tension can create bright flashlighting points or localized shadows.
10
What Is Clouding?
Clouding describes soft, cloudy white patches visible on dark gray or black screens, typically caused by inconsistent mechanical spacing between optical sheets.
11
Backlight Uniformity vs IPS Glow
Backlight bleed is a fixed physical defect along edges. IPS glow is an inherent viewing-angle phenomenon that moves and changes intensity as your head moves.
12
Why Dark Screens Reveal More Problems
Human vision is non-linear and becomes extremely sensitive to subtle contrast variations at low luminance levels when adapted to a darkened room.
13
How Viewing Angle Affects Uniformity
On large panels (27" to 34" curved or flat), your eye-to-corner angle is significantly oblique, making corners look different even on perfectly uniform panels.
14
Why Some Panel Variation Is Normal
Every mass-produced consumer LCD and OLED exhibits minor variations. 10% to 15% peripheral luminance falloff is standard for consumer displays.
15
How Professional Uniformity Measurements Work
Hardware calibrators measure a 9-point or 25-point grid with a colorimeter probe, recording precise nits and Delta E values relative to the central coordinate.
16
Browser Test Limitations
Web browsers provide controlled, mathematically pure test patterns, but cannot read physical optical output. The test relies on careful human inspection.
Frequently Asked Questions
Screen uniformity describes how consistently a monitor reproduces brightness and color across its entire surface from edge to edge and corner to center.
Display solid, neutral full-screen patterns (such as 50% gray, pure white, and near-black) in a dark or dimly lit room and visually check for darker borders, tinted patches, or cloudy areas.
Use white and 50% gray screens. Inspect the outer 10% perimeter of the panel and corners to see if they appear visibly dimmer than the central focal area.
Display full-screen pure white or light gray. Scan for color temperature shifts, such as one side looking slightly warm (yellowish/pink) and the other side looking cool (bluish).
Corner darkening (vignetting) is common on edge-lit LCDs due to optical light guide distance and mechanical frame pressure blocking peripheral light diffusion.
Edge brightening is usually caused by backlight bleed or IPS glow where LED emitters leak light around panel frame bezels.
Clouding (or mura) refers to diffuse, blotchy patches of uneven brightness across dark or gray backgrounds caused by uneven layer contact inside the LCD stack.
Yes. For photo editing, color grading, graphic design, and dark-room entertainment, high uniformity prevents misleading color perceptions and distracting shadows.
Most consumer displays exhibit 5% to 15% luminance variation across edges and corners. Professional graphic monitors maintain uniformity within 3% to 5%.
IPS panels generally deliver superior viewing-angle color consistency, though edge-lit IPS models can suffer from corner IPS glow on dark backgrounds.
Yes. While VA panels boast high static contrast, their narrower viewing angles can cause visible gamma and color shifts when viewed off-center.
OLEDs achieve flawless zero-black uniformity, but can exhibit near-black vertical banding (at 5% gray) or subtle pink/green tinting at extreme viewing angles.
Yes. Extreme brightness (0% or 100%) exaggerates backlight imperfections. Testing at normal operating levels (100–150 nits) gives the most realistic evaluation.
Significantly. Looking at corners from an off-axis distance creates angular distortion. Always inspect from your regular sitting distance or view each zone perpendicular to your eyes.
No. A browser has no optical sensor or camera to capture physical photons emitted by the screen. All assessments rely on controlled visual inspection.
No. A calibrated hardware colorimeter or photometer probe is required to record absolute luminance in cd/m² (nits).
No. Delta E measures physical color difference using spectrophotometer probes. Browser scripts cannot read color emissions.
Professionals place a colorimeter across a 9-point, 15-point, or 25-point grid on the panel, recording luminance and color temperature at each coordinate.
Yes. Thermal cycling, LED phosphor aging, panel sagging, and mechanical stress from tight monitor arms can subtly alter uniformity over years of use.
Ready to Check Your Screen?
Run full-screen black, gray, white and color patterns to visually inspect your display for uneven brightness and color.