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With more people spending more time in front of computer monitors it is important to purchase a quality monitor that will provide crisp, bright images, while reducing the strain on your eyes.

The large majority of monitors have LCD panels, which stands for liquid crystal display. A voltage is applied to the liquid crystals in each pixel, which rotate to allow the pixel to produce a color. This is a very basic way of explaining it, but if the same voltage is applied to the crystals for long periods, they may retain their same shape and continue producing the same image. The type of content displayed also impacts potential image retention. An operating system"s user interface, like the taskbar or windows, usually stay on the screen for long periods, and that could cause image retention when you close them. You can get away with a gaming monitor that has image retention if the game doesn"t have many static elements.

The type of panel used also affects image retention. With monitors, there are three common types of LED-backlit LCD panels: IPS, VA, and TN. Although image retention is something that can vary between units, IPS panels generally suffer from image retention more than the other two. However, this doesn"t mean that VA or TN panels are immune to image retention, and we"ve seen some VA panel monitors that show signs of it, like the Samsung Odyssey G9.

OLED panels are different from LCD panels because each pixel is individually-lit, as there"s no backlight. These panels tend to suffer from image retention. Many monitor manufacturers are reluctant to use OLED panels because they also have the risk of long-term permanent burn-in.

OLED panels are known for both image retention and permanent burn-in. Only a few monitors have OLED panels, and they"re more popular with TVs. Many OLED TVs that we"ve recently tested don"t show signs of image retention, but they"ll always face the risk of permanent burn-in. We don"t expect this to be an issue for people who watch varied content, but it could pose a problem if you watch a lot of content with static elements, like the news, or if you use your OLED TV as a PC monitor. LED TVs appear to be immune to long-term burn-in, which you can read about here.

Lowering brightness:Lowering the brightness can help reduce image retention, and in the long run, burn-in, on OLED panels. It shouldn"t really affect image retention on LEDs.

Screensavers:When you take a break from your screen, like when you get up for a coffee or to eat, use screensavers while the computer is idle. A slideshow would be ideal since the computer rotates between different images, and one image doesn"t stay on for a long period.

Temporary image retention happens when high-contrast elements stay on the screen for a long period and appear to stay on-screen for a few moments after they"re removed from the display. Although it"s rare, some monitors may show signs of image retention, but the images generally disappear after a few moments. There are a few ways to help reduce the risk of image retention, like lowering the monitor"s contrast or using screensavers. Temporary image retention is also different from long-term burn-in, so you shouldn"t have to worry that your monitor is broken if it shows some image retention.

Gamma: Gamma doesn"t control the depth of black, but it does control the amount of detail you will see in dark portions of an image. If you find it difficult to make out detail in dark images, consider making a slight adjustment to the gamma.

One frequently asked question is which is more important, a panel"s native contrast or contrast with local dimming? It"s a good question. The answer is a bit complicated, but basically, it depends. Unlike TVs, most monitors don"t have a local dimming feature. The few that do, generally speaking, don"t work very well. They usually have very small zone counts, and the algorithms can"t keep up with fast-paced motion, so the leading edge of a bright object in a dark scene ends up looking darker than the rest, and there"s a trail of light behind it.

Because of these issues with local dimming, it"s almost always more important to look at the native capabilities of a monitor instead of the contrast ratio with local dimming. Because most monitors have poor local dimming features, there"s usually not that much of a difference between the native contrast of the panel and the contrast with local dimming when tested with a checkerboard pattern. In fact, of the 23 monitors with local dimming that we"ve tested on our latest test bench, only 4 of them can improve contrast by 10% or more with our test pattern through local dimming.

ANSI Checkerboard: The most generally accepted way to measure contrast; a checkerboard pattern very similar to ours is used, but with an asymmetric test pattern. The ANSI method measures the output in all 16 squares and averages the values for the white and black squares. It usually produces very similar results to our own.

Monitors use different display technologies, each with advantages and disadvantages. Knowing which type of panel is used in your monitor can already give you a good indication of what to expect in terms of contrast ratio:

Even within the same panel types, it"s normal for the contrast to vary a bit between units, even of the same model, due to manufacturing tolerances. Manufacturers used to provide the typical contrast ratio for each monitor, but recently, some brands, including LG, have started listing the minimum contrast ratio you could get. For IPS and TN panels, this difference usually isn"t very significant, and most people shouldn"t worry about it, but for VA panels, the variance between individual units and measurement techniques can be significant. For example, the LG 32GN600-B is advertised to have a typical contrast ratio of 3000:1, but according to LG, it could be as low as 1800:1 for some units. We measured a contrast ratio of 3248:1, almost double the minimum contrast for that model.

DisplayTester makes it possible to test almost every aspect of your device"s LCD/OLED screen. Using Google Cast it is possible to test the display quality of your TV. It is designed to allow full screen testing also on devices with soft keys (hiding the soft keys in ICS and later, immersive mode in KitKat and later).