Screen Uniformity Test
Check brightness and colour uniformity with full-screen grey, white, and RGB fields. Use it in a dark room to spot clouding, mura, dim corners, and tint shifts; the 3×3 grid helps compare corners with the centre.
← → ← → change field · G grid · Esc exit
Photographing the screen exaggerates unevenness. Judge by eye at a normal distance in a dark room, after a few minutes of warm-up.
Soft brighter patches on low-to-mid greys; smear-like clouding is the dirty-screen effect.
Angle-dependent silvery or warm corner haze on IPS panels; it changes as you move your head.
Dimmer edges or corners from backlight falloff and off-axis viewing near panel edges.
Fixed fine blotches or grain from manufacturing; it stays in place at every viewing angle.
- 5% grey — Deep shadow — near-black clouding and the dirty-screen effect
- 25% grey — Low-mid tone — clouding and dirty-screen effect show most here
- 50% grey — Mid grey — overall brightness evenness and mura
- 75% grey — Light grey — vignetting and dimmer edges and corners
- White — Peak white — tint shifts, warm or cool corners, and smudges
- Red — Red channel uniformity and blotchy tint
- Green — Green channel uniformity and faint banding
- Blue — Blue channel uniformity and corner tint
Panel uniformity
Panel uniformity is how evenly brightness and colour hold across a flat tone, such as 50% grey. LCD backlights, diffusers, and cells are never perfectly even, so small variations are normal. Full-field patterns make the worst case obvious; judge from normal viewing distance after warm-up.
Common causes
- Backlight and diffuser: edge-lit light can fall off or pool, while diffuser and local-dimming zones add variation.
- Panel lottery: two units of the same model can differ in clouding, tint, and mura because of normal manufacturing tolerances.
- Pressure and handling: tight bezels, shipping stress, or pressing the screen can leave bright or dark patches.
- Warm-up: brightness and tint can drift for the first few minutes, so let the display settle before judging it.
Clouding, bleed, and glow
Clouding is soft brighter patches across lit greys, sometimes seen as dirty-screen smears. Backlight bleed is fixed edge or corner light on black. IPS glow is angle-dependent corner haze that brightens or fades as you move your head. This tool is for grey-field evenness; use the Screen Bleeding Test for pure-black edge bleed.
Dim edges and corners
Edges can look darker from real backlight falloff and from off-axis viewing: you see corner pixels at a steeper angle than the centre. VA panels shift contrast more, IPS panels glow more, and both can show vignetting on white or light grey. Move your head to separate fixed unevenness from angle effects.