Display test
Backlight Bleed Test
Backlight bleed is light leaking through an LCD, usually at a corner or along an edge, when the picture is black. This page gives you the dark fields. It does not measure the leak, and it does not decide whether a warranty will cover it.
Click the field for the next one. It stays until you click. Full screen is only that field. Space runs them. Esc leaves.
What the backlight bleed test is for
Black and three dark grays
Black, 2%, 5%, and 10% gray. A leak that only appears on pure black can be milder than a patch that stays on dark gray.
A dark-room look
Full screen is only the dark field. It stays on black until you click, so you can look at the corners without the picture changing.
Glow versus leak
The page explains the difference. IPS glow shifts when you move your head. Backlight bleed stays in the same corner.
Not a stuck-pixel test
A sharp bright dot on black is a stuck pixel. A soft patch in a corner is the leak. They are different faults and different pages.
Backlight bleed and IPS glow
Backlight bleed is light leaking through an LCD, usually at a corner or along an edge, when the picture is supposed to be black. It stays in the same spot when you move your head a little. People notice it in a dark room on a dark scene, not on a spreadsheet.
IPS glow is the silver or gray sheen many IPS panels show toward the corners. It shifts as your angle changes. A little glow from off-center is common. A bright flashlight patch that stays put from straight on is the leak people return screens for.
OLED and other self-lit panels do not have a backlight, so they do not have backlight bleed. A bright dot on an OLED black field can still be a stuck pixel. Check that on the dead pixel test. Uneven dark gray belongs on the uniformity test.
The black screen page is the same black field, with the color download tools. This page adds the darker grays and the head-movement check so black is not the whole test.
How to check for light leak
- Make the room dark. Turn the lights off. A lamp in the glass looks like a bright corner. Wait a minute so your eyes adjust.
- Sit straight on. Use a normal distance. Do not start from the side, or IPS glow will look worse than it is at your desk.
- Open black in full screen. Press the badge or F. The display is only black. Look at the four corners and the edges. Click for the next dark gray. Esc leaves.
- Move your head. If the sheen shifts, treat it as glow. If a corner stays bright from straight on, treat it as bleed.
- Step to 2%, 5%, and 10%. A leak that disappears by 10% gray is easier to see on black. A patch that remains on dark gray is stronger. Neither number is a lab measurement.
Why use this backlight bleed test
Black first, then the dark grays
Pure black shows a flashlight patch in a corner. 2%, 5%, and 10% gray show whether that patch is only a trick of pure black or whether it still sits on a dark picture. One black frame is not the whole check.
Head movement is the difference
A leak stays in the same spot when you move your head. The silver sheen many IPS panels show in the corners shifts as your angle changes. Sit straight on first, then lean a little. The page cannot label the panel for you.
OLED is named honestly
A self-lit panel has no backlight, so it cannot have backlight bleed. A bright dot on black can still be a stuck pixel. Check that on the dead pixel test. Do not return an OLED for a leak it does not have.
No brightness number
The page does not know your backlight setting and does not measure the leak in nits. A dark room makes faint glow easier to see and also makes ordinary glow look worse. Look again with the lights you actually live with.
What people use the bleed test for
A new IPS monitor in a dim room
Open full screen on black, sit straight on, and look at the four corners. A patch that stays put is the leak people ask sellers about. A haze that slides when you lean is the glow that comes with many IPS panels. The seller’s policy, not this page, decides a return.
A corner that only shows at night
Turn the room lights down, not necessarily off, and hold black, then 5% gray. If the corner disappears in ordinary light and you never see it in a film, it may not be worth a return. If you see it from your chair on a dark scene, note it while the window is open.
A bright dot that is not a leak
A single lit point on black is often a stuck pixel, not a cloud. Change to white. A stuck pixel keeps the wrong color. A leak is a soft area, not one dot. The dead pixel test is the page for that dot.
Uneven dark gray that is not a corner leak
Soft patches across the middle of a dark gray belong with uniformity, not with a corner flashlight. Use the screen uniformity test for 25%, 50%, and 75% gray. This page stops at the dark fields.
What the dark fields cannot prove
The page cannot measure the leak in nits, and it cannot tell you whether a warranty will cover it. Some bleed is normal on LCD panels. The question is whether you can see it from your chair in the kind of room you actually use.
Local dimming, a high brightness setting, and a “dynamic contrast” mode change how black looks. If the corners flare, try the monitor’s standard picture mode before you decide the panel is faulty. This page cannot change those settings.
A phone held close to your face makes corner glow look worse. Judge a monitor at desk distance. The dead pixel test is the next step for a sharp dot, and the uniformity test is the next step for a cloudy gray.
Frequently asked questions
What is the difference between backlight bleed and IPS glow?
Bleed stays in the same corner when you move your head. IPS glow shifts with your angle. Check from straight in front, in a dark room, before you mix the two up.
Why are there dark grays, not only black?
Some leaks are obvious only on pure black. A patch that is still visible on 5% or 10% gray is easier to notice in real dark scenes. The steps are there so you can see which kind you have.
Does OLED have backlight bleed?
No. There is no backlight to leak. Use black to look for a stuck bright pixel instead, and use the uniformity test for uneven gray.
A bright dot showed up on black. Is that bleed?
A sharp dot is a stuck pixel, not a corner leak. Open the dead pixel test and see if it stays the wrong color on white and on the primaries.
Should the room be completely dark?
Dark enough that you are looking at the panel, not at a lamp in the glass. Total darkness makes small glow easier to see. Judge it at the brightness you will live with.
Can this page tell me the panel type?
No. The test is the same fields on any screen. You already know if you bought an IPS LCD or an OLED. The page does not detect it.
The bottom of the screen had a black bar during the test.
Full screen on this page is only the dark field. There is no bar on it. Click for the next gray. Esc leaves. A bright corner you see is the panel, not a button.
Is a little corner glow a reason to return the monitor?
Often no, if it only appears when you lean to one side. A bright corner you can see from your normal seat in a dim room is worth checking against the return policy. This page does not make that decision.
How do I run a backlight bleed test?
Dim the room, open full screen on black, and look at the corners from straight in front. Then move your head a little. Click through 2%, 5%, and 10% gray. The field stays until you click.
How do I tell IPS glow from backlight bleed?
Glow shifts or fades when you change angle. Bleed stays on the same part of the panel. A little corner haze from off-center is common on IPS. A bright corner that stays put from your normal seat is the leak. One screen can show both.
Should the room be completely dark?
Dark enough that a lamp is not reflecting in the glass. A fully black room makes every faint haze look severe. After you find a patch, turn the lights back to the way you watch and see whether you still notice it.
Do OLED screens have backlight bleed?
No. There is no backlight to leak. Use black to look for a stuck pixel, and use the gray uniformity page if a near-black field looks uneven. Do not treat an OLED corner the way you would treat an LCD leak.
Can I press on the panel to change the leak?
Do not press the panel. Pressure can make a leak worse or create a new one. This page only shows the field. It does not include a pressure test, and it will not tell you to push on the glass.
Will this page say whether I should return the monitor?
No. It shows black and the dark grays. A return depends on the seller’s rules and on whether you can see the patch from the seat you use. Take a note of the corner and the field. The decision is still yours.
