TV and monitor reviews often talk about flowering or the effect of the aura and whether a particular model suffers from it. Here’s why the bloom occurs and how you can spot it on your monitor or TV.
Full range of local opacity and bloom
Blooming, also known as the halo effect, is an artistic display that occurs when light from isolated bright objects on a screen streams into the dark areas around it. This creates a kind of aura around the object, hence the name “halo effect”. Associated with a full range of local dimming on LED screens.
Monitors and TV manufacturers mainly use two types of displays these days – LED-backlit LCD and OLED. Whereas OLED screens are self-emitting and can turn off individual pixels for perfect blacks, LCD screens with LED backlights must rely on local dimming — full matrix or edge-lit — to create deeper black levels. While full matrix local dimming is more common in TVs, monitors primarily use sharp-light local dimming. But none of the local dimming methods are perfect, and boom is a defect of full local dimming.
What causes the corona effect?
In full local dimming, manufacturers place LEDs behind the entire screen to better control the backlight according to the content displayed. These LEDs are divided into dim areas, and when the screen has to show a bright object surrounded by dark areas, it turns on the LED area behind the object while the surrounding LED areas remain dimmed. As a result, light from the LED’s lit area flows into and softens the surrounding unlit areas. This creates a halo around the shiny body. It is more visible around isolated bright objects, for example, streetlights, subtitles or stars.
Unfortunately, all LED-backlit LCD TVs with a full range of local dimming suffer from fading. But it’s the amount of bloom that affects your TV viewing experience. If there is a very light bloom, it will be less noticeable and distracting. However, if there is a lot of bloom, it may be unconvincing.
The number of local dimming areas on your screen also affects how much bloom you see. If there are fewer areas covering larger areas, this can lead to more blooming. But more blackout areas can reduce blooming.
How to check if Blooming is on screen
You can perform a star field test to determine if the screen is experiencing breakouts and the extent of the problem. The star field test is basically watching a recording of the clear night sky. Because the star field contains tons of bright stars separated by a night sky, it’s excellent at highlighting issues like blooming and even black squashing, where the opacity causes shadow detail or subtle highlights to be lost. In an ideal situation, you will see bright stars with enough black space between them. Otherwise, halos will appear around the stars.
Rtings.com, an excellent resource for TV and monitor reviews, among other products, does its own boom test and mentions the same in the reviews. It can also help you see if there is a boom on a TV that you are planning to buy.
Can you fix the bloom or reduce its effects?
Unfortunately, there is little you can do to avoid or fix blooms, apart from buying a different TV or monitor with or without blooms. But, some displays come with local dimming settings that you can tweak to get the best possible experience. The low local dimming option reduces backlighting and makes blooms less noticeable. Unfortunately, this also means that local dimming will be less effective at improving the contrast ratio of the screen. A higher local opacity setting will improve the contrast ratio, making the brightening more visible. You can choose the option that suits you best.
In addition, you can try to lower the backlight to reduce blooming. The backlight option can usually be found under “Picture” in your TV or monitor settings.
Related: OLED screen burn-in: How worried should you be?
Until OLED panel prices and brightness reach LED levels, full-matrix local dimming will continue to play a vital role in helping LED-backlit LCD panels deliver better black levels and a greater overall contrast ratio. This means that it will be difficult to avoid blooming. What you can do as a consumer is to look for TVs that have more local dimming areas and are less prosperous.