Backlight bleed test

Svetlana December 12 2021

Nowadays, LCD computer monitors and televisions are still the preferable choices. Of course, they have their advantages, but they also have several negative features. Sometimes, you can see the light diversion on its edges or across the whole screen while looking at it. This display defect is known as backlight bleed.

Is it removable? In some cases, you can do it. But now we will speak about the other thing. In our article, we will discuss how to check whether your display has this defect and if it can be considered so.

What is the backlight bleed on your monitor?

The backlight bleeds on the monitor is leakage of light through the pixels. It can be seen as a bright area on the edge of the screen or in the center of it. Mostly, it appears while viewing dark images or videos on the monitor. This defect is usually not very noticeable, but sometimes it becomes quite annoying while watching movies or playing games.

What causes the backlight to bleed?

The leakage of light through the pixels usually happens because of their poor assembly and bad contact inside the monitor's frame. Generally, such problems happen due to several reasons: 

A defective pixel (the brightness is permanently turned on or off) Misalignment of display components Loose connection between cables and internal elements Uneven lighting across the screen Backlight bleed may also occur due to misalignment and deformation of monitor's casing indulging of inner components.

What is IPS glow?

IPS glow is a backlight bleed that is usually seen on the edges of the IPS monitors. This defect is caused by the way the light shines through the pixels on an IPS panel. It can be eliminated by using a matte screen protector.

What monitors may have such problems?

Almost all monitors may have backlight bleed to some extent. The severity of this defect usually depends on the monitor's design and construction. Some monitors, such as the ones with an edge-lit LED backlight, are more likely to have this issue than others.

Is backlight bleeding normal?

To put it simply - no. Some models may have a little backlight bleed, but it should not be very noticeable. If you see that there is a significant problem with the light diversion on your monitor, then this means that you have a broken product.

Detection

So, how can you know whether your screen has a backlight bleed defect? To examine your monitor for backlight bleed, you need to reproduce a big-screen video or simply open a completely black picture. If you see the light that leaks on your screen’s edges, it means that your monitor has a backlight bleed.

There is one important note – you should not confuse it with the IPS glow. You can see it only when you look at the screen at a specific angle on the IPS panel.

Today the significant part of LCD monitors with LED-backlit and television sets have this backlight bleed defect. In a significant part of cases, you can hardly notice it, but if you look at the completely black picture in the dark room, you will see it. Sometimes having a backlight bleed can be severe, and on this occasion, you need to replace your monitor or return it with the money back.

How to check if your monitor has this problem?

In order to determine whether you have this issue, you need to perform a backlight bleed test.

As we have already known, one of the ways to test your monitor for backlight bleed is to reproduce a full-screen video. Before testing, we recommend bringing down the lights (or even turning it off at all) and adjusting your monitor to a reasonable lightning level.

The preferable light is around 30-50% (but you also need to consider your displays’ potential to provide the maximum lightning when adjusting the monitor). There is also one recommendation for you – do not make the 100% lighting. In this case, you will not see anything clear.

If you see the light diversion around the monitor’s edges or across the entire monitor, it means there is a backlight bleed, and you need to return your monitor or repair it. And when constantly using the monitor, you do not see any leaking light, but if you only see it during the backlight bleed testing, you have nothing to worry about. 

Another way to test your monitor is as follows. For that, you will need:

  • A piece of paper
  • A ruler or any other straight object with a length of at least 10 cm
  • A pen or a pencil
  1. Set your monitor to the blackest picture you can find – either by using a screensaver or by opening a file with only black letters on a white background.
  2. Measure the width of the bright area on the edge of the screen.
  3. Now take the ruler and place it vertically against the edge of the bright area.
  4. Make sure that one end of the ruler is exactly on top of the bright area and draw a line along the ruler with your pen or pencil.
  5. Measure the length of this line and divide it by 10 to get an approximate value in cm for backlight bleed width defect severity (if the result is more than 1 cm, the monitor has severe backlight bleed).

If your monitor has no backlight bleed on the edges of its screen, you can use it without any problem. However, if it has this issue, we recommend returning the product or replacing it with a new one.

In case you want to test the backlight bleed on the monitor that you already have with or without defects, please use high contrast picture, not all-black. It is very important because the black color in your monitor is often a low level of gray and it doesn’t help you to detect the leakage of light from the LED matrix.

And again, about IPS - if you use a monitor with the IPS panel, you need to ensure that you do not confuse the IPS glow with the backlight bleed. We will repeat that to see the IPS glow, you need to look at your monitor at a specific angle. And it is the other topic for discussion.

So, now you know to check your monitor for backlight bleed. No matter what result you will have, you do need to panic and run for a new monitor. In the great part of cases, it is possible to get rid of it.

How to get rid of this defect?

Unfortunately, there is almost no way to reduce the effect (except for some special DIY tricks). You should avoid using your monitor in complete darkness or in very bright light while watching dark scenes. Also, try not to choose the completely black picture for testing and make sure that your room is bright enough while adjusting your monitor’s brightness and contrast controls to more suitable values than max or min.

Close all unnecessary applications before testing which will significantly ease finding out whether you have such an issue or not.

If you do have a backlight bleed, the easiest way to reduce it is to return your monitor and get a new one. We hope that this guide was helpful for you. If you have any other questions, feel free to leave a comment below.

Can you prevent backlight bleeding?

There is no sure way to prevent backlight bleed, but there are a few things you can do to minimize it.

First, try to avoid using your monitor in complete darkness or in very bright light while watching dark scenes. Second, try not to choose the completely black picture for testing and make sure that your room is bright enough while adjusting your monitor’s brightness and contrast controls to more suitable values than max or min.

Finally, close all unnecessary applications before testing which will significantly ease finding out whether you have such an issue or not. If you do have a backlight bleed, the easiest way to reduce it is to return your monitor and get a new one.

Does it depend on the monitor`s price?

No, it does not. Monitor with the same price and even better parameters can have backlight bleed while some cheaper monitors can be flawless.

What brands give you the lowest chance of having backlight bleed on their monitors?

High-quality brands such as LG, Dell, BenQ, and Acer often offer budget models with an extremely low probability of having such issues. Some professional reviews help to spot those cases where lower quality manufacturers ignore this problem during the production process or place the LED matrix in the wrong way so that there is no way to fix it.

However, keep in mind that any product has its good and bad sides – either it will have problems or not – depending on a specific batch or a factory line.

Is backlight bleed common?

Yes, backlight bleed is a common issue with monitors. In fact, it is so common that there is almost no monitor that does not have some degree of backlight bleed.

What about laptop screens? Backlight bleed is also common with laptop screens, although it is not as widespread as with monitors.

Final word

Backlight bleed is a common issue with monitors, and while it can't always be avoided, there are a few things you can do to minimize it. If you do have a backlight bleed, the easiest way to reduce it is to return your monitor and get a new one. Thanks for reading!