Grey Uniformity Test
The grey uniformity test fills your screen with a neutral 50% grey — the single most revealing slide for spotting backlight inconsistencies, panel pressure damage and manufacturing variation. Dark patches at the edges, bright hotspots near the corners, or subtle tinting that shifts colour across the screen are all signs of a non-uniform display. The test also includes solid colour fields afterward, so you can check whether an issue is tied to one colour channel.
50% grey (centre) is the most sensitive tone for uniformity evaluation
Before you test: Warm up the panel for 15–30 minutes, disable any auto-brightness or dynamic contrast modes, and dim ambient lighting. Cold panels and auto-brightness interfere with results.
- Click Start Test and go fullscreen (F11 on desktop).
- Start with 50% grey — scan edges, corners and centre for patches.
- Use Next slide / Previous slide to move through grey and solid colour fields; the +/- controls only adjust greys.
- Move slightly off-axis to distinguish IPS glow (normal) from uniformity defects (fixed).
- If severe on a new product, contact your retailer before the return window closes.
What the grey test reveals
| What you see | Likely cause | Normal? |
|---|---|---|
| Brighter patches near corners | Edge-lit backlight bleed | Common on budget LCD |
| Darker band at bottom/top edge | Edge-lit backlight shadow | Mild variation is typical |
| Fixed tinted patch (e.g. yellow corner) | Panel manufacturing variance or pressure damage | May warrant return |
| Glow that brightens when viewed from the side | IPS glow — viewing angle characteristic | Normal for IPS panels |
| Distinct dark blob mid-panel | Pressure or impact damage to LCD layer | Defect — not normal |
| Even overall on grey, odd on one colour only | Sub-pixel or colour channel issue | Depends on severity |
Grey Uniformity — FAQ
What is the grey uniformity test?
It fills your screen with a 50% neutral grey — the mid-tone most sensitive to backlight and panel inconsistencies. Non-uniform backlighting, pressure damage or manufacturing variation shows as lighter or darker patches and colour tinting.
What level of non-uniformity is normal?
Mild, gradual variation is typical — especially on large edge-lit LCDs. Large tinted patches, strong vignetting or distinct hotspots may be unacceptable on a new display and could warrant a return.
Why does grey reveal problems better than white or black?
White can blow out subtle brightness differences; black hides them. Mid-grey sits in the most perceptually sensitive luminance region, making small inconsistencies obvious to the eye.
Does panel warm-up matter?
Yes. Allow 15–30 minutes before testing. Cold panels often look less uniform; judging a cold display can give a false result.
Can pressure damage cause grey uniformity problems?
Yes. Physical pressure on an LCD — from a tight laptop lid, a bag pressing the screen, or a fall — can damage the liquid crystal layer, causing permanent bright or dark patches visible on grey.
Will OLED look different to LCD?
Yes. OLED has very uniform blacks but can show subtle colour shifts off-axis — that is a normal panel characteristic. IPS LCDs may show IPS glow from corners; neither is the same as a uniformity defect.