Backlight bleed test

A pure black full-screen image that makes light leaking from the edges of an LCD panel easy to see.

Runs right here in full screen — nothing is uploaded. Press Esc or ✕ to exit.

How to run the test

Darken the room. Bleed is hard to see in daylight.
Set brightness to the level you normally use. This is the result that matters for everyday viewing.
Start the test and look straight at the center of the screen from your normal viewing distance.
Check the edges and corners for patches of light.
Optional strict check: repeat at maximum brightness. This exaggerates even small leaks, so use it to compare panels, not to judge normal use.

Bleed or IPS glow?

Backlight bleed: bright patches that stay in the same spot when you change your viewing angle, unlike IPS glow, which clearly changes or seems to move. Usually caused by pressure on the panel or uneven assembly.
IPS glow: a soft silvery or yellowish glow in the corners that changes or fades when you move your head. It's normal for IPS panels.

OLED screens have no backlight, so they can't bleed. If you see light on black on an OLED, it's more likely a raised black level or the screen isn't showing true black.

Is it a defect?

Small amounts of bleed visible only in a dark room at full brightness are common, and many manufacturers don't count them as defects. Large patches visible during normal use, especially in dark movies, are worth reporting while the device is still under warranty or within the return period.

For photos and more detail, read backlight bleed vs IPS glow. Then try the black level test to see how dark shades are handled.

Frequently asked questions

Why should the room be dark?

Bleed is light leaking from the backlight. In a bright room your eyes adapt and the leaks are hard to see. A dark room shows how the screen looks during movies and games at night.

Does bleed get worse over time?

It can change slightly as a panel warms up or if the frame is under pressure, but it doesn't usually grow on its own. Sudden new bright patches after a drop or pressure point to physical damage.

Do OLED screens have backlight bleed?

No. OLED pixels make their own light, so there is no backlight to leak. A glow on an OLED black screen usually means it isn't really showing pure black, or it isn't an OLED panel.