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Backlight Bleed Test

Check for backlight bleed on a full-black field — and tell it apart from IPS glow.

Turn the room lights off first. Bleed is only judgeable in the dark.

Looking at the corners and edges — what did you see?

How this test works

The screen fills with pure black, which turns every subpixel off, and anything you can still see is light that should not be there. The tool then asks a second question that most bleed pages skip: whether the light moves when you move your head. That single question separates the two things people call bleed. IPS glow shifts and fades with viewing angle because it is the panel's polarising layer leaking at an angle — every IPS panel has it, and no manufacturer accepts a return for it. Backlight bleed stays fixed in place because it is light escaping around the edge of the panel, and that sometimes is a fault. Answering the first question without the second is how people end up raising warranty claims for something inherent to the technology they bought.

What the results mean

Light that moves with your head
IPS glow. Inherent to the panel type, present on every IPS display, never a warranty matter.
Light that stays fixed
Backlight bleed. Light escaping past the edge of the panel, which at high levels can be a manufacturing fault.
Corner bleed
The normal pattern for an edge-lit LCD, where the backlight runs along one edge and the diffuser cannot spread it perfectly.
Pixels painted
How much of the panel the black field actually covered. Bleed lives at the edges, so a fill short of them is looking away from the fault.

Common problems and fixes

It looks terrible here but I never notice it normally
Then it is very unlikely to be worth pursuing. This test is the worst case; the standard that matters is whether you can see it on real content at your normal brightness.
The light moves when I move — is that bad?
No, that is IPS glow rather than bleed. It is a property of how IPS panels work and every one of them has it. A replacement unit will have it too.
One corner is much worse than the rest
Check the mount. Over-tightened VESA screws or a bad clamp flex the frame and press the panel, which creates corner bleed that was not there before.

Frequently asked questions

How much backlight bleed is normal?

Some is normal on every edge-lit LCD — it is a consequence of putting the light source along one edge. The practical threshold is whether you can see it during ordinary dark-scene viewing rather than only on a black fill in a dark room.

What is the difference between IPS glow and backlight bleed?

Glow shifts and fades as you change viewing angle; bleed stays in the same place no matter where you sit. Glow is inherent to IPS panels, bleed is about how the panel is seated in its frame.

Is bleed covered by warranty?

Often not. Many manufacturers exclude uniformity from the standard warranty unless it exceeds a published tolerance. A return inside the return window has no such threshold, which is usually the better route if the unit is new.

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