Pick a color and brightness level, enter fullscreen, and look for dark corners, brighter edges, clouds, or IPS glow on your monitor. Different colors reveal different uniformity issues.
Screen Uniformity Test is a free, browser-based screen testing tool that runs the full check instantly in your web browser.
A "uniform" display shows the exact same color and brightness across every region of the panel. Real-world LCD and OLED monitors are never perfectly uniform — the backlight (LCD) or pixel-aging pattern (OLED) inevitably introduces small variations. The question for buyers and QC is how big those variations are. Professional color-critical work (photo editing, video grading) demands tight uniformity; gaming and general use tolerates more.
Clouding looks exactly like its name — milky, cloud-shaped patches of brighter or slightly tinted gray visible when displaying a solid mid-gray or dark color. It's most common on VA panels, where slight LCD alignment variations across the panel area produce uneven light transmission. Minor clouding is considered normal; severe clouding is usually a warranty-able defect.
These are different, despite being often confused:
Set a uniform fullscreen color and look carefully. Mid-gray reveals clouding best because grays show the slightest luminance shifts. Near-black reveals bleed and glow because any stray light stands out. Solid primary colors (red, green, blue) reveal subpixel-level issues — a weak blue subpixel cluster, for example, will show as a purple patch on a solid blue field. Testing at multiple brightness levels is important since some issues only appear in specific bands.
Screen Uniformity Test FAQ
