Screen Uniformity Test
Even gray fields with an optional grid overlay to reveal clouding, vignetting and backlight bleed.
Test in a dim room. Look for blotches, bands, bright edges or darker corners on each gray level.
Quick answer
What is the Screen Uniformity Test?
A screen uniformity test shows dark and gray fullscreen fields so you can see whether brightness and color are even across the panel. It reveals backlight bleed at the edges, clouding on LCD and IPS screens, IPS glow, vignetting and the dirty screen effect on large TVs.
Key features
- Black, dark gray and mid-gray test fields
- Brightness steps for checking clouding in a dark room
- Side-by-side guidance for IPS glow vs backlight bleed
- Fullscreen with all browser chrome hidden
Why use it
- Spot panel faults that are covered by warranty
- Compare two monitors or a replacement fairly
- Takes about two minutes in a dark room
Built and tested by Whitson Rao
About the Screen Uniformity Test
Display even gray fields from dark to light, with an optional grid overlay, to reveal clouding, vignetting, dirty screen effect and backlight bleed. Best done in a dim room.
How to use the Screen Uniformity Test
Dim the room lights and let your display warm up for a few minutes.
Press F for fullscreen and start with the darkest gray to look for bleed at the edges.
Step through lighter grays and look for blotches, bands or darker corners.
Turn on the grid overlay to compare specific zones of the screen.
Common uses
Backlight bleed
Near-black fields reveal light leaking from the edges of LCD panels.
Dirty screen effect
Mid-grays show vertical bands or blotches on TVs during panning shots.
Vignetting
Compare corners against the center to spot darker edges.
Panel lottery check
Compare two units of the same model before keeping one.
Frequently asked questions
Why does my screen look uneven on gray?
No panel is perfectly uniform. Small brightness differences are normal; large blotches, strong bands or bright corners may be worth reporting if your device is new.
Should I test in a dark room?
Yes. Ambient light hides subtle bleed and clouding, so a dim room makes the test far more revealing.
Can the camera show what I see?
Phone cameras often exaggerate bleed and clouding. Judge with your own eyes and use photos only as a rough reference.
Sources and further reading
Guides and fixes that use the Screen Uniformity Test
- GuideScreen Uniformity Test: How to Check for Backlight Bleed, IPS Glow, and CloudingCheck your monitor for backlight bleed, IPS glow, clouding, vignetting, and dirty screen effect (DSE) using solid gray and black test screens.
- GlossaryOLED vs LCD Displays: Architecture, Contrast Ratios, and LongevityComprehensive architectural breakdown of OLED vs LCD (IPS, VA): infinite contrast, true black levels, response times, text clarity, and burn-in prevention.