---
title: "Screen Uniformity & Backlight Bleed Test | Flicker Button"
description: "Fill your screen with black and grey levels to check for backlight bleed, IPS glow, clouding, dark corners and banding. Free and runs in your browser."
url: https://flickerbutton.click/screen-uniformity-test/
---

02 Screen test

# Backlight bleed & uniformity test

Black and evenly spaced greys, full screen, so light leaking from the edges, blotchy patches and dim corners have nowhere to hide.

## How to check for bleed

Darken the room, set the brightness you normally use and give your eyes a minute. Sit where you usually sit, look at the screen straight on and start with black. Then step up through the greys: problems that hide on black often show at 5–25%, and the 50% grey is where smudgy bands appear. Turn on the grid to compare the corners with the middle.

## What you might see

- **Backlight bleed:** bright patches along an edge that stay put when you move your head. Common on LCDs; OLEDs have no backlight to leak.
- **IPS glow:** a silvery shine in the corners that changes as you move. It is a property of the panel type, not a fault.
- **Clouding:** blotches across dark greys, often on large LCD TVs.
- **Vignetting and tint:** corners darker than the centre, or a colour cast in one area on white.
- **Banding:** visible stripes in the smooth ramp, where the steps between greys are too coarse.

Judge by eye, not by phone photo: cameras lift shadows and make most screens look worse than they are.

## Questions

**How much bleed is normal?**

Some is normal on most LCDs, especially on a black screen in a dark room. What matters is whether you notice it in films and games at your usual brightness. Makers do not publish a common limit, so a return depends on the seller.

**Does backlight bleed get worse over time?**

It usually stays much the same. Bleed often comes from pressure on the panel, so check the stand and the frame are not twisted.

**Why are there custom grey levels?**

Some faults only show at one brightness. Slide the level until a patch is most visible, then compare it with the same spot on other screens.