The symptom: glowing corners on a dark screen
You set up a new monitor, put on a film at night, and the corners of the letterbox bars look hazy instead of black. Or a game's loading screen shows one edge noticeably brighter than the rest. People tend to call all of this 'backlight bleed', but three different things hide under that label: true backlight bleed, IPS glow, and clouding (also called mura). They have different causes, and that matters because the right response is different for each.
IPS glow is a property of the panel technology. Virtually every IPS monitor has some, so exchanging the unit usually gets you another one that glows. Heavy bleed and clouding, on the other hand, vary from unit to unit, and a replacement can genuinely be better. Work out which one you are looking at before you start a return.
It also helps to reset expectations. An LCD keeps its backlight on all the time and uses the liquid crystal layer to block light for dark areas. That blocking is never perfect, so a black screen in a dark room looks dark grey rather than truly black. That is normal. The question is whether the brightness is even, or whether specific areas stand out.
How to check properly: dark room, normal brightness, black screen
Use the fullscreen check in our monitor test. It is the same tool used for finding dead pixels: it cycles through solid white, black, red, green and blue, a click or any key moves to the next colour, and Esc exits. For bleed you want the black screen. It runs in the browser, so there is nothing to install.
Conditions make or break this test. Turn the room lights off and set the monitor to the brightness you actually use. At 100% brightness every LCD looks bad, and if you never run it that high the result tells you nothing about daily use. Let the monitor warm up for half an hour or so first, and give your eyes a minute on the black screen to adapt before judging.
Sit the way you normally sit: centred, at your usual distance. Pressing your face close to the panel or looking up at it from below exaggerates glow enough to make a perfectly good monitor look faulty. Once you have looked at black, step through the other solid colours too. Clouding often shows up more clearly on a uniform colour or a dark grey scene than on pure black.
Telling them apart: move your head
The most reliable test is simple. With the black screen up, slowly move your head left and right, then up and down. Backlight bleed is light escaping where the panel meets the bezel, usually because of a small gap or uneven pressure. It appears as bright patches along edges or in corners, and those patches stay in exactly the same place with the same shape no matter where you look from. They often have a fairly defined outline, like torchlight leaking through a crack.
IPS glow behaves the opposite way. It is a soft glow, mostly in the corners, that shifts as your viewpoint changes. Move your head and the bright area slides or changes strength, and its tint can swing between yellowish and bluish depending on the angle. Back away from the screen and it fades noticeably, because you are now seeing the corners at a shallower angle. If stepping back makes it disappear, it is glow. If it stays put, it is bleed. That rule sorts out most cases.
Clouding, or mura, is identified by location. Instead of hugging the edges, it shows up as cloudy, uneven blotches in the interior of the panel, caused by pressure or uniformity variations in the panel layers. Like bleed it does not move with your head, but its borders are soft and it can sit right in the middle of the screen. If a dark scene pans across and a faint blotch stays fixed while the picture moves underneath it, suspect clouding.
Why photos make it look worse than it is
Most bleed photos posted online look far worse than what the owner saw in person. A phone camera pointed at a dark screen raises exposure time and sensitivity automatically to brighten the frame, which amplifies brightness differences your eyes could barely detect into glaring patches. The same monitor, shot from the same spot, can look flawless or disastrous depending purely on camera settings.
So do not compare your screen with someone else's photo, and do not condemn your monitor based on your own photo either. The standard that matters is whether it bothers you in real use. Put on a dark film or game at your normal brightness and watch it properly. If the patches keep pulling your attention while you are focused on the content, that is a real problem. If you can only find them by staring at an empty black screen, it rarely matters in practice.
You will still need photos as evidence if you file a return. If your camera lets you lock exposure manually, bring it down until the photo roughly matches what your eyes see, and note the room lighting and the monitor's brightness setting. It saves a lot of back-and-forth with support.
Panel types, and what actually reduces it
What you can expect depends on the panel. OLED has no backlight at all. Each pixel emits its own light and switches off for black, so backlight bleed simply does not exist there. VA panels have higher contrast and far less corner glow than IPS, but they are still backlit LCDs and can have bleed and clouding. On mini-LED monitors, the halo around a bright object on a dark background is blooming, a separate effect that comes from dimming the backlight in zones. It is a limit of the technique, not bleed.
Glow and mild bleed respond well to changes in how you use the monitor. Lowering brightness helps most, since whatever leaks scales with the backlight level. Bias lighting, a soft light on the wall behind the monitor, keeps your pupils from opening fully, so blacks look deeper and patches become harder to see. Sitting a little further back with your eyes level with the centre of the screen reduces corner glow.
On some monitors, overtightened stand or VESA mount screws press on the back of the panel and cause bleed, and backing them off slightly can ease it. Keep this to external screws you are meant to touch. Prying at the bezel or opening the housing can give the manufacturer grounds to refuse warranty service, so if you are still inside the return window, leave it alone and consider an exchange instead. Rubbing or pressing on the screen is not recommended either, as it risks damaging the panel.
Returns, and a checklist for the first few days
Unlike dead pixels, bleed and clouding rarely have a numeric threshold in warranty terms. Policies tend to use vague wording about being outside normal range and are decided case by case once you file a claim. In practice your strongest tool is not the manufacturer warranty but the retailer's return window. Check how long it is before you buy, and finish your testing inside it.
Be realistic before you exchange. There is essentially no such thing as an IPS panel with zero glow, and a replacement may have a similar amount of bleed in a different spot. Judge by real content at normal brightness from your normal seat. If it clearly bothers you under those conditions, file the return promptly rather than hoping you will get used to it.
Here is what to run in the first few days. Check the black screen in a dark room for bleed, glow and clouding. Cycle all five colours of the same fullscreen check to look for dead and stuck pixels; our dead pixel guide covers how to classify them and what exchange policies usually say. Look at the grey gradient and gamma step patterns for banding. Then run the refresh-rate measurement, which takes about five seconds, to confirm you are getting the Hz you paid for. If the number comes out low, our guide on refresh rate not being applied walks through the settings to check. The whole routine takes about ten minutes.