This is going to be disappointing, but there’s no getting away from it. Mini LED isn’t the display technology you’ve been waiting for. Mini LED monitors are a bad idea in theory, and in practice they are even worse.
In fact, what mini LED technology does best is provide fantastic specs. 1,400 nits of brightness? To check. Contrast ratios measured in millions? Yes. Ultra-bright highs, inky-black lows, epic full-screen brightness, zero burn-in risk, support for ultra-high refresh rates? The jobs.
Just don’t mention the actual experience. Because it’s kind of boring.
Okay, he has a huge advantage that is pretty real. Mini LED is available now in gaming monitors you can buy and in all shapes and sizes. This gives it a very clear advantage over microLED, which remains entirely theoretical in the context of PC monitors, but is the promised holy land of high-end panel design.
It’s also more widely available in many more screen sizes than OLED technology, which has only just begun to appear in PC monitors but is limited by virtue of being derived from OLED TV panels. So you can’t get, say, a 27-inch or 32-inch 4K OLED gaming monitor, they start at 42 inches and up. The smaller 27-inch OLED displays are ‘only’ 1440p and still cost $1,000 and up. Disgusting.
The problem with the mini-LED
Anyway, here’s the catch: Mini LED technology is and always will be a gimmick. It’s a crumbling semi-fix for a display technology with chronic inherent shortcomings. And it creates a new set of problems to replace the ones it fixes.
But let’s not get ahead of ourselves, first let’s cover what mini LED really is, where it fits into the display technology continuum, and how it compares to other panel options.
The first thing to understand about mini LED is that it is merely a backlight technology for LCD panels. It’s not a display technology per se. It’s meant to make up for the fact that LCD panels aren’t very good at blocking out light.
This is a problem because, on a conventional LCD monitor, the backlight is on all the time. You basically have the same light source for a pixel that should be light and another pixel that should be dark.
In practice, LCD panels always let some light through. So those dark pixels in any image leak some light. And the brighter you want to make the light pixels, the more the dark parts of the image will be washed out with unintentional light leakage.
The mini LED solution is to replace that single, big, dumb backlight with an active array of much smaller lighting zones. The result, in theory, is the ability to adjust the light output on the panel to match the luminance topography of the displayed image.
So you turn the backlight on in the zones behind the brightest picture elements and backlight for the darkest areas. Presto, you’ve dramatically increased contrast and unlocked the true possibilities of high dynamic range. In other words, you can have a screen that’s brighter than before and also offers far superior contrast. Work done.
Where the problem lies, and where the mini LED obviously isn’t as good as some alternatives, involves precision. Both OLED and microLED offer true per-pixel lighting control. In both technologies, each pixel is its own fully addressable light source. There’s no backlight, just full control from max brightness to full off for each pixel.
In comparison, the mini-LED backlight zones are shared across multiple pixels. And this number of pixels is large. Really big.
Not enough zones
Take, say, a 32-inch 4K monitor. This is a popular form factor lately for high-end mini LED backlit gaming monitors. The native resolution of a 4K LCD panel is 3840 by 2160 pixels.
That comes to a total of 8,294,400 pixels precisely. Which is a lot. Now, a mini-LED display with 1,152 dimming zones looks pretty good too. But if we do the math, each zone, each element of the mini-LED backlight, fully illuminates 7,200 pixels.
Of course, many elements on the screen are much smaller than that. The small lines that make up text, for example, can only be a few pixels wide. Point stars in a space scene too. Other elements might be a few hundred pixels but still much smaller than a given blackout zone. So there’s your first problem. Lighting is not granular enough.
You are therefore left with a choice. Do you light everything and support what is known as blooming around bright objects due to the zones being larger than the things they are lighting? Or do you just turn the mini LEDs up for really big areas of bright picture data?
Bear in mind here that on a 32-inch 4K panel, you’re talking about a backlight ‘resolution’ of approximately 45 by 25 zones. Imagine the size of these zones individually. Imagine if that was the actual screen resolution. In a word: Blocky!
So, what you end up doing in practice are varying compensations from one screen to another, depending on the manufacturer’s preferences. There is no right or wrong. It’s all compromise.
Mini LED displays look particularly bad on the Windows desktop. As you move a bright window onto a dark background, you’ll often see zones turning on and off. It’s so clumsy.
Even with a static image, you often encounter issues such as a brightness gradient in the text. The text itself is typically not substantial enough to trigger the darkening algorithms. Therefore, the brightness of text, especially bright text on a dark background, is dictated by the image elements next to the text in question. The result is usually a real mess or just really dark text that you can barely read because the algorithm hasn’t deemed it worthy of a little backlighting effort.
Kludgy Calibration
Now the counterargument to all this goes like this. The point is missing. Mini LED technology is not about web browsing. It’s about games and movies. And admittedly, the on and off zones are much less obvious in gaming or watching movies.
But the problems remain. Some LED mini monitors, for example, can be very aggressive when it comes to dimming the backlight. The result is loss of shadow detail.
The reality is that you need a fair amount of backlight coming through the LCD apertures to let in enough light to make the difference between two fairly dark shades of gray visible next to a patch of total darkness. So, you have to choose what you prefer.
If you want a really low black level, you need to dim the backlight, which causes the gray tones to blend into the dark. Or you turn it up a notch to let the details show and the black levels fade.
Then there’s the backlight sync issue. It’s pretty hard work directing eight million pixels. But now you need to time 1,152 backlight zones to match whatever the pixels are doing. This is terribly difficult work when milliseconds matter. Furthermore, mini LEDs have fundamentally different pixel response characteristics from LCD. So this has to be taken into account.
In other words, the complexity of these trade-offs, forced by the mismatch in dimming zone and pixel size, adds up to greater complexity in terms of synchronizing everything perfectly.
The net result is that we’ve seen a number of mini LED displays here at PC Gamer and none have been really good. Some had really awful obvious issues like flickering. But they were all terribly awkward on the Windows desktop and a mixed bag in the game. There is no need to name names. All of them, without exception, were a little bad, especially given the high prices.
At best, to use local dimming technology, you need to toggle it on and off when loading a game. You can’t just leave it running, it’s too dark on the desktop. This might not be the end of the world. It certainly wouldn’t be if it could be solved by pressing a single button, which is usually not the case.
But in-game image quality with dimming enabled always betrays the tradeoffs and decisions made by whoever set up the algorithms. There is no right and wrong in this sense. Just choices between various compromises, none of which come close to replicating true per-pixel lighting.
lack of alternatives
In our experience, if you want a good HDR experience on an LCD monitor, the best results come from the latest VA panels with the brightness boosted on a monolithic backlight. The best VA technology offers up to 4000:1 static contrast, much better than the 1000-1300:1 of IPS technology (except LG’s IPS Black panels that haven’t appeared in gaming monitors yet). This is enough for very strong highs while maintaining reasonable black levels.
The only partial exception to this is mini LED technology in laptops. (opens in new tab). As the panels are much smaller, the dimming zones shrink proportionately and some of the issues become less visible. But they are still there and over time they only become more frustrating.
Of course, none of this is to say that there is a perfect alternative. OLED has its own issues, obviously, very limited full-screen brightness, as well as the risk of burn-in. The subpixel structure of all OLED gaming monitors currently on the market is also problematic. So far, none use conventional (for PC) RGB pixels, and that’s a problem for things like font rendering that addresses the panel at a subpixel level.
In theory, microLED is the answer to all our flat-panel needs with bright, burn-in, OLED-compatible per-pixel lighting. But microLED technology currently costs a lot of money, and the technology still cannot be scaled down to deliver PC-relevant resolutions in practical panel sizes. The smallest 4K microLED panel right now is about 70 inches in diameter. A corresponding 32-inch monitor would be sub-1080p and have huge pixels. Useless.
These issues will be resolved eventually. But in the meantime, don’t think mini LED comes close to per-pixel technologies when it comes to contrast control and HDR performance. Why not.
If mini LED technology could be had almost free as an extra, it would make sense. You could use local dimming occasionally and not begrudge the fact that it was usually off. But it’s expensive and complex to implement, and adds hundreds of dollars, at the very least, to the price of a monitor. Paying over $1,000 for something so obviously flawed is no fun, and as a stopgap, it’s already destined for obsolescence.