If I may quote a recent review: “Let’s be clear, OLED is the best TV tech available today. And LG is the source of OLED.” But if you can’t afford OLED, what about LG’s “Super UHD” range. Let’s dig into the LG 65SK8500 Super UHD TV from that range.
Nano Cell Technology
The screen is the same size as that of the OLED, and virtually all the facilities and features are identical. Except that there’s a Super UHD panel instead of an OLED panel. And there’s a recommended retail price of $4,799 rather than the OLED TV’s $6,399. That’s quite the saving.
There is one more difference. The OLED TVs include LG’s latest picture processor, the Alpha9. This TV scores the Alpha7.
So what is a Super UHD panel? Basically, it’s an LCD panel with LED backlighting, but with an additional wrinkle. LG calls it “Nano Cell Technology”. TVs create colour by combining red, green and blue dots. LCD dots aren’t coloured; they are white, black or some level of grey in between. They are turned into red, green or blue with colour filters over them.
Colour filters are imperfect. A green filter will let through a very small amount of light that looks to us more red than green. And vice versa. Likewise for green and blue. And vice versa. (But not for blue and red. Nor vice versa. They are at opposite ends of the visible spectrum.)
It seems that LG’s Nano Cell Technology absorbs some of the overlap between red and green, creating primary colours which are purer. Then, by combining them intentionally rather than accidentally through leakage, a greater range of colours can be created.
Blacks and brightness
Now the main advantage of OLED over LCD/LED TVs is that OLED does black perfectly, LCD/LED doesn’t. That’s because LCD panels can’t entirely block the light coming from the LEDs in the backlight. Years ago makers started addressing this by putting an array – a grid if you like – of backlights behind the LCD panel. The picture processor controls each element of the grid. In any darker parts of the picture, they could be turned down. This was typically called something like Local Area Dimming.
Then TV styles changed, and premium TVs had to be thin, so the business moved to edge lighting, which allowed thinner panels. Many still had some form of Local Area Dimming, but it was less precise.
Lately, there has been a trend back to a good array of lights behind the panel. And that’s what the LG 65SK8500 TV incorporates. LG calls it “Full Array Dimming”.
The resolution of the panel is UltraHD, which is to say 3840 by 2160 pixels, or around 8.3 million pixels. What’s the resolution of the LED array behind the panel? I saw a press release for a different brand of TV just yesterday which boasted of a local dimming array of more than five thousand zones. There’s no official information about the number of zones offered by the LG 65SK8500 TV. We do know that it isn’t the best on offer from LG because the company has released a higher (costing $200 more) model which seems to differ only by including “Full Array Dimming Pro”.
But you can estimate the size of the grid by displaying an image that is fully black, except for a couple of bright pixels. And then seeing where the blackness glows. I estimate the grid as having four lighting zones across by eight up and down, for a total of 32.
The black levels of this TV are pretty good. But that local dimming isn’t really very local, so there was quite often a visible halo of relative brightness around moving bright objects on dark backgrounds.