TV and monitor reviews often talk about blooming or halo effect and whether a particular model suffers from it. Here’s why blooming happens and how you can spot it on your monitor or TV.
Full matrix local flowering and dimming
Flourishing, also known as the halo effect, is a display artifact that occurs when light from isolated bright objects on a screen filters into darker areas around the screen. This creates a kind of halo around the object, hence the name “halo effect.” Is associated with full matrix local dimming on LED screens .
Monitor and TV manufacturers mainly use two types of screens these days: LED-backlit LCD and OLED . While OLED displays are self-emitting and can turn off individual pixels for perfect black color, LED backlit LCDs have to rely on local dimming (full matrix or edge lighting) to create deeper black levels. While full-matrix local dimming is more common in televisions, monitors primarily use edge-lit local dimming. But neither method of local dimming is perfect, and flowering is a deficiency of full matrix local dimming.
What Causes the Halo Effect?
In full-array local dimming, manufacturers place LEDs behind the entire screen to better control the backlight according to the displayed content. These LEDs are divided into dimming zones, and when the screen needs to show a bright object surrounded by dark areas, it turns on the LED zone behind the object while the surrounding LED zones remain dim. As a result, the light from the illuminated LED zone filters into the surrounding non-illuminated areas and illuminates them. This creates a halo around the shiny object. It is most noticeable around isolated bright objects, such as a street lamp, captions, or stars.
Unfortunately, all full-array local dimming LED-backlit LCD TVs suffer from a bloom. But it is the amount of bloom that affects the TV viewing experience. If there is a very light bloom, it will be less noticeable and distracting. However, if there is a lot of flowering, it can be unsightly.
The number of local dimming zones on a screen also affects the number of flowers you see. If there are fewer zones covering larger areas, then it could lead to more blooming. But more fade zones can reduce blooming.
How to check for flowers on a screen
You can perform a star field test to identify if a display is blooming and how big the problem is. A star field test essentially consists of observing a recording of a clear night sky. Because a star field has tons of bright stars separated by a night sky, it’s great for highlighting issues like blooming and even the black crush , in which dimming causes a loss of detail in shadows or subtle reflections. In an ideal situation, you will see bright stars with enough black space between them. Otherwise, halos will appear around the stars.
You can find videos of star field test in Youtube. Of course, any intro of Star wars it will also do.
Rtings.com An excellent resource for TV and monitor reviews, among other products, it conducts its own bloom tests and mentions the same in reviews. It can also help you determine if there are flowers on a television you plan to buy.
Can you fix the bloom or limit its effects?
Unfortunately, you can do little to prevent or fix blooming other than buying a different TV or monitor with little or no blooming. However, some displays come with local dimming settings that you can modify to get the best possible experience. The low local dimming option will dim the backlight less and make the bloom less noticeable. Unfortunately, this also means that local dimming will be less effective in improving the contrast ratio of your screen . A high local dimming setting will improve the contrast ratio, making the bloom more visible. You can choose the option that suits you best.
Also, you can try turning off the backlight to decrease blooming. The backlight option can usually be found under “Picture” in your TV or monitor settings.
An inevitable sacrifice?
Until OLED panel prices and their brightness reach LED levels, full-array local dimming will continue to play a vital role in helping LED-backlit LCD panels provide better black levels and a higher contrast ratio in general. That means it will be difficult to avoid blooming. What you can do as a consumer is search televisions that have more local attenuation zones and less flowering.