How to run a backlight bleed test
- Make the room dark. Turn off the lights and close the curtains. Bleed that is invisible in daylight can be obvious in a dark room, and a dark room is where you watch films and play games.
- Set brightness to a normal level. Around 30–50% is ideal. Maximum brightness exaggerates bleed you would never notice in real use.
- Start the test. The page goes fullscreen on pure black and every control fades away after a couple of seconds.
- Look from your normal seat, straight on. Note any lighter patches along the edges or in the corners. Then step through the dark gray screens to check for clouding.
- Move your head. Glow that shifts, grows or fades as you move is IPS glow. Light that stays exactly where it is, whatever your angle, is backlight bleed.
Backlight bleed vs. IPS glow vs. clouding
Backlight bleed
Light leaking around the edges or corners of an LCD panel because of uneven pressure in the frame. It stays in the same place at every viewing angle.
IPS glow
A silvery or amber sheen in the corners that changes with your viewing angle and distance. It is normal for IPS panels and not a defect.
Clouding
Blotchy, cloud-like patches across the middle of the screen, most visible on the 2–10% gray screens. Common on large LCD TVs.
Blooming
A halo around bright objects on a dark background, caused by local dimming zones on mini-LED and full-array TVs and monitors.
How much backlight bleed is normal?
Almost every LCD shows a little light at the edges on a pure black screen in a dark room. What matters is whether you notice it in normal use. A good rule of thumb: if you can see the bleed during a dark movie scene or a dark game at your usual brightness, it is worth returning the display while you still can. If you only see it on a black test screen at full brightness, it is usually considered within tolerance.
Cameras exaggerate bleed badly. If you photograph it for a warranty claim, lower the exposure until the photo matches what your eyes see.
Blooming test for mini-LED and local dimming
The blooming screen moves a small white square slowly across a black background. On displays with local dimming, the backlight zones behind the square light up and create a glow or halo around it. Some blooming is expected on any zone-based backlight; strong halos or zones that visibly switch on and off as the square passes point to a weak dimming algorithm. OLED screens should show no blooming at all.
Can backlight bleed be fixed?
Bleed comes from the physical build of the panel, so software cannot fix it. It can sometimes settle slightly over the first weeks of use. Some owners loosen the screws around the back panel or bezel to relieve pressure, but opening a display can void its warranty and damage the panel. If the bleed bothers you, the safest fix is an exchange or return within the seller's return window.
Tip: run this test together with the dead pixel test as soon as a new monitor, laptop or TV arrives, so you can return it in time if needed.
Frequently asked questions
How do I test my monitor for backlight bleed?
Darken the room, set brightness to around 30 to 50 percent, then start the fullscreen black screen and look at the edges and corners from your normal seat. Step through the dark gray screens to check for clouding, then move your head to separate IPS glow from true backlight bleed.
Is backlight bleed normal?
A small amount of edge light on a black screen in a dark room is normal for most LCD monitors, laptops and TVs. It becomes a problem when you can notice it during normal dark content, such as films or games, at your usual brightness.
What is the difference between IPS glow and backlight bleed?
IPS glow changes or fades when you move your head and is a normal trait of IPS panels. Backlight bleed stays in exactly the same place and shape at every viewing angle and is caused by light leaking through the panel frame.
Can backlight bleed get worse over time?
It usually stays the same, and it sometimes improves slightly during the first weeks as the panel settles. Heat and pressure on the frame can make it worse, so avoid pressing on the edges of the screen.
Do OLED screens have backlight bleed?
No. OLED pixels make their own light and switch fully off for black, so OLED screens have no backlight bleed, IPS glow or blooming. Use the OLED burn-in test instead to check them.
Why does my photo of backlight bleed look much worse than in person?
Phone cameras raise the exposure in dark scenes, which makes faint bleed look bright. Lower the exposure in your camera app until the photo matches what you see, especially if you are sending it for a warranty claim.