Do the bright thing

By Simon Willis

I thought I had seen “Stranger Things”, a Netflix show about a quartet of kids battling mutant creatures in small- town America. Then I watched it again on a brand-new TV. A 65-inch monster made by Sony, it dominated my old Samsung the way Orson Welles once dominated conversation, putting the company in the shade with its size and vividness.

Its quality was especially noticeable at one particular moment. Eleven, a girl with supernatural powers, is wandering through the Upside Down, a copy of the real world that differs from it in one crucial respect: everything’s dead. As she stalks the dark corridors of the local school, details that I hadn’t noticed before popped out of the murk. I’d barely registered the periodic table on the classroom wall, but now I could read every character. I didn’t remember the clock above the blackboard, but this time I noticed that it was just past ten. On my old screen, the portal to the real world that glows at the end of a corridor seemed bright. Now its incandescence threatened to melt the television, and the corona around its edge had a far richer palette of primrose, scarlet, mauve and magenta. As Eleven looked through it, the dust around her face fluorescing like embers, I could pick out every strand of pale down on her cheek.

It is often said that we’re living in the golden age of television. But whatever you think of the dramatic quality of the shows on Netflix or HBO, one thing’s for sure: they look better than ever. The descriptive power of TV – its ability to render texture, colour and contrast – is growing fast. Directors have advances in screen technology to thank.

The TV I was trying out had what manufacturers call 4K HDR, a pair of acronyms that mark a giant leap in picture quality. 4K refers to the screen’s resolution. Television is a kind of electronic pointillism: as with painting, the smaller and more numerous the points are, the more realistic the picture will be. These points of light are called pixels and, until around 2014, TVs had about 2m of them at most. As manufacturers have found ways to make pixels smaller, their density has increased. The ultra-high resolution of today’s TVs is called 4K because of a fourfold growth in the number of pixels to 8m. It is thanks to the added sharpness they deliver that close-ups of textures, like the down on Eleven’s face, stand out so clearly. Resolution is about to improve again. This year the first 8k televisions will go on sale, with 32m pixels and a picture that, in its smoothness and clarity, will be nearly indistinguishable from looking out of the window.

HDR, meanwhile, stands for “high dynamic range”. That’s how companies refer to the ratio between the darkest picture a TV can generate and the brightest. HDR is driven by two lighting technologies that dominate the television industry – light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). Though they have similar names, they offer two very different routes to the dramatic levels of contrast that define HDR: LEDs shine very brightly and OLEDs go very dark.

An LED is made from a bundle of semi-conductors that shines when charged with electricity. In an LED TV, a bank of these illuminates an array of pixels made of liquid crystals from behind. These channel light from the LEDs onto the screen. Thanks to improvements in materials and the efficiency with which they convert electricity into light, LEDs are getting more powerful. The brighter they are, the better they can represent effects like light glinting off a car bonnet, streaming from a torch or pouring through a portal to another world. TV-makers measure brightness in units called “nits”: a mid-range television might kick out around 400; an expensive model with the latest LED technology will manage almost 2,000. This year, Sony unveiled a prototype screen that can generate 10,000 nits.

You can generate contrast not just by making a screen brighter but also darker. That’s where OLEDs come in. In an LED TV the pixels act as shutters that block light to create dark images. But even when they are closed, some light bleeds through. However bright the vibrant colours are, the darks are never perfectly black.

OLEDs work better. They are thin films of organic molecules that fluoresce when jolted with electricity, and they’re so small that the pixels themselves can be made of them. There is no longer a need for pixels to block the backlight; the OLED is just turned off altogether, delivering pure black and even greater contrast.

As these screens become more common, television networks are adapting shows especially for them. After they are recorded, shows are sent to post-production studios where teams of colourists pick out certain details and intensify their highlights and colours especially for 4K HDR TVs. The quantity of such material available on Netflix and Amazon is growing. Last December “Blue Planet II” became the first programme from the BBC to be released in this way. The skill of the colourists can be seen in the blobs of light shimmering across a coral reef and on the glowing flanks of bioluminescent fish emerging from the inky depths.

A new technology is emerging that may push picture quality even higher. At the 2018 edition of the Consumer Electronics Show (CES), a jamboree of gadgets and gizmos held every January in Las Vegas, Samsung unveiled a 146-inch TV called The Wall, which will go on sale later this year. It is powered by microLEDs.

In theory they offer two advantages: though they’re as bright as regular LEDs, they’re also the size of individual pixels, which means they should be able to function just like OLEDs, delivering equivalent levels of darkness. There is a downside, however. As LEDs grow smaller, it becomes harder to wire them up. Samsung has yet to work out how to compress them sufficiently to create 4K resolution on a smaller device. For those who can’t squeeze a 146-inch screen into their living room, there may be a long wait.

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