Backlight bleed test
Click the field to fill the screen with black in a dark room, then look at the edges and corners for light leaking through.
Backlight bleed test workspace
How to use
4 short steps.
Dim the room and use normal brightness
Turn the lights off, let your eyes adjust for a minute, and keep the brightness you normally use.
Click the field to go full screen
The screen fills with black. Sit where you usually sit and look at each edge and corner.
Move to the gray fields
Press Space or the arrow keys for 5%, 10%, and 20% gray. Turn on the zone grid if you want to describe where a patch sits.
Move your head a little
Lean left, right, up, and down. Glow that moves with you is IPS glow; a patch that stays put is bleed.
What the result means
Match what you see to one of these.
If a bright patch stays in the same spot, it is backlight bleed
If light leaks along an edge or corner and stays there when you move your head, the panel is letting backlight through at that point.
If the glow shifts when you move, it is IPS glow
If a corner brightens as you move off-center and fades when you sit straight, that is normal IPS panel behavior, not a defect.
If the patch is away from the edge, it is clouding
If you see broad, uneven bright areas across the middle of the screen, that is clouding. The uniformity test shows it more clearly on gray.
Troubleshooting
If the test fails, try these in order.
Turn off local dimming and dynamic contrast
These settings change the backlight while you watch. Turn them off in the picture menu and look at the black field again.
Lower the brightness
Bleed scales with brightness. Set a brightness you can live with and check whether the bleed still shows on dark scenes.
Loosen a tight bezel
Bleed is sometimes caused by a bezel pressing on the panel. Some people gently massage the area with a soft cloth; do this at your own risk, then check the black field again.
Compare with the uniformity test
Open the screen uniformity test and look at 5% to 25% gray. If the problem is across the whole screen rather than the edges, it is clouding.
What this test can't tell you
Where a browser check stops.
- The page cannot measure how much light leaks or tell you whether it is within a manufacturer's tolerance.
- OLED screens have no backlight, so a bright area on an OLED black field is a different fault.
- Phone cameras exaggerate bleed on a dark screen, so judge it with your eyes at normal brightness.
FAQ
Common questions about this test.
How much backlight bleed is acceptable?
If you can see it at normal brightness on dark scenes from your usual seat, it is worth returning the display while you still can. If it only shows at maximum brightness on a black field in a dark room, it is typical for an LCD.
Does backlight bleed go away over time?
True bleed does not go away, because it comes from the panel assembly. Bleed caused by a tight bezel sometimes eases slightly as the frame settles, but do not count on it.
How do I fix backlight bleed?
You cannot fix the panel itself. Lower the brightness, turn off local dimming, and avoid dark rooms if it bothers you. If it is severe, use the warranty or return window.
What is the difference between backlight bleed and IPS glow?
Bleed is light leaking through a fixed spot at the edge. IPS glow is a soft brightening of the corners that changes with your viewing angle and is normal for IPS panels.