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
Detects dropped or skipped frames at your refresh rate with rAF timestamp analysis and a visual reference bar
Lagom-style 1px pixel grid, multi-size text samples, color-fringing blocks, and an RGB sub-pixel ruler to evaluate display sharpness
Detect dead, stuck, or hot pixels on screens
Detect if your display runs at 60Hz, 144Hz, 240Hz or higher
Check color accuracy, gradient banding and backlight uniformity
Check your LCD monitor for backlight bleed, IPS glow, and clouding
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