Blooming test
Bright shapes on a pure black screen, so the halo of light a local dimming backlight paints around them has nowhere to hide. This is the test for mini-LED and full-array LCD TVs, where the backlight sits in zones and every zone is bigger than the object it is trying to light. Made to run on the television itself, in a dark room.
The test
This test needs JavaScript to run. Everything below still explains what blooming is and what a bad result means, so the page is useful either way.
Five bright-on-black patterns
A small square, a dot field, subtitles, a moving box and a hard boundary. Step through with the arrow keys, in a dim room, at your normal picture settings. Watch the black around each bright shape, not the shape itself.
How to read it
Excellent zone control, or an OLED, where every pixel makes its own light and blooming cannot exist.
Blooming. The backlight zone behind the shape is bigger than the shape, so it lights a patch of black around it.
Zones switching on ahead of and behind the object. Normal on local dimming sets; the question is how visible it is from your seat.
Little or no local dimming, common on edge-lit sets. No halos, but black is really dark grey. A different trade, not a fault.
Ordinary zone behaviour at a hard edge. Judge it together with the subtitle pattern, which is the case you will actually watch.
Quick answer
Blooming is the halo of light around a bright object on a dark background, and it comes from local dimming: An LCD backlight is divided into zones, each zone is larger than a subtitle or a star, so lighting the object also lights some black around it. This test shows bright shapes on pure black so you can judge how visible the halos are from your own seat, in a dim room. Some blooming is inherent to every local dimming LCD, including mini-LED; more zones make it smaller, and OLED has none because each pixel lights itself. It is a characteristic, not a defect.
What did you see?
Pick the closest match and we take you straight to what causes it and what fixes it.
Keep testing
Backlight Bleed TestOr jump straight to another test:
What this test can and cannot tell you
Blooming depends on settings and room light as much as on the panel, so here is the honest frame.
Reliable. Bright shapes on pure black are the worst case for a zoned backlight, which is exactly the point. If your set blooms, these patterns show it.
Not possible here. No browser can read the zone count, and manufacturers rarely publish it. What you can judge is the result: The smaller and dimmer the halos, the better the zone control.
Strongly. The local dimming setting (often called Local Dimming, Local Contrast or UHD Dimming) trades halo size against black depth. Test at the setting you actually watch with, and try the steps of that setting while a pattern is up.
Judge in the dark. In a lit room, reflections hide halos and every set looks clean. Blooming is a dark-room, dark-content phenomenon; test it the way you watch films at night.
It is not. Blooming is inherent to every local dimming LCD; more zones shrink it but never remove it. Only OLED is free of it, by construction. If the halos bother you within the return window, the answer is a different panel technology, not a repair.
Knowing what you are looking at
Blooming
A halo around a bright object on dark background. The backlight zone is bigger than the object, so it lights black pixels around it. Most visible on subtitles, credits, starfields and street lights at night.
Not the same as bleed
Backlight bleed sits at the edges and corners and never moves. Blooming follows the bright content around the screen. The bleed test covers the fixed kind.
Why mini-LED still blooms
Mini-LED means many more, smaller zones, hundreds to thousands, so halos get much tighter. But a zone is still thousands of pixels, so a single subtitle still lights more than itself. Better, not gone.
Why OLED does not
Every OLED pixel makes its own light, so a white dot on black lights exactly one dot. That is the trade the panel comparison guide walks through, halos against brightness and burn-in care.
Questions people ask
What is blooming on a TV?
A soft halo of light around bright objects on a dark background, most visible on subtitles and starfields at night. It comes from local dimming: The LCD backlight is divided into zones, each zone is bigger than the object it lights, so some black around the object gets lit too. OLED screens do not bloom, because every pixel produces its own light.
Is blooming normal or a defect?
Normal, on every local dimming LCD including mini-LED. It is a property of zoned backlights, not a fault, so it is not a warranty case. What varies is how visible it is: More zones and better processing make halos smaller and dimmer. If it bothers you on a new set, the honest options are a different picture setting, a different model, or OLED, decided while the return window is open.
How do I reduce blooming?
Try the local dimming setting first, often called Local Dimming, Local Contrast or UHD Dimming: A lower step usually shrinks halos at the cost of slightly greyer blacks, and the best compromise differs per set. Turning brightness or contrast enhancers down helps too. Then re-run these patterns at each step and keep the one that looks best from your seat.
Does mini-LED have blooming?
Yes, just less of it. Mini-LED backlights use hundreds to thousands of zones instead of dozens, so halos become much tighter and dimmer. But every zone still covers thousands of pixels, so a subtitle still lights more than itself. Only OLED removes blooming entirely, because it has no backlight at all.
Why do subtitles glow on my TV?
Subtitles are the perfect storm for a zoned backlight: Small, bright, white, on dark film content, near the bottom of the picture. The zones behind them switch on and light a patch of the dark scene around the text. Lowering the local dimming step usually softens it, and some players can move subtitles into the letterbox bar, which sits in its own zones.
Blooming or backlight bleed, which one do I have?
Watch where the light sits. Bleed clings to the edges and corners and stays put on a full black screen. Blooming surrounds bright content and moves with it. Run this test for blooming and the backlight bleed test for the fixed kind; a set can have both.
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