نمایشگرهای گوشی 4K: دیوانگی محض یا شگفتی بزرگ ؟!

In the last few years, as smartphone design has basically settled on rectangular slabs of glass, we’ve seen manufacturers take the competition over who produces the best gear to a new battle ground: the specs war. Nowhere is this clearer and more easily visible than smartphone displays, the resolutions of which have been on a steadily upwards trend for the last couple of generations of flagship phones. Historically, smartphone screens have got that little bit better every season. The HTC One X had a 720p HD screen; the Galaxy S4 and HTC One both stepped up to 1080p Full HD displays, and we’re now seeing 2K displays pop up on the likes of the LG G3. The trend would suggest, therefore, that 4K displays will be commonplace within the next two or so generations of flagship phone. Does the world need more than the G3’s QHD display? To understand why a 4K screen on a phone might (or might not!) be a good idea, you first have to understand exactly what 4K means. At a basic level, all screens have a resolution, which is expressed as the number of horizontal pixels times vertical pixels – for example, 1280 x 720, meaning that there’s 1280 rows of pixels horizontally, and 720 vertically. In theory, the higher the resolution, the crisper and less blurry the image. The resolution is often abbreviated to a snappier name – for example, the ‘HD’ logo that’s slapped on most TVs these days. High Definition means a resolution of at least 720 pixels vertically, and ‘Full HD’ is a minimum of 1080. However, there are several levels above mere ‘HD’. 2K video has to be at least 2,000 pixels wide horizontally (Full HD (1080p) is generally 1980 pixels horizontally). QHD (Quad HD) has a horizontal resolution a little higher, at 2,560 pixels, meaning that there’s four times as many actual pixels than in 1080p, hence Quad-HD. But the gold standard of ultra hi-res is currently 4K, which offers a display resolution normally of 3840 x 2160. It’s a standard that’s starting to creep into high-end TVs and computer monitors, and even more common services like YouTube and GoPro are starting to record or playback 4K footage. iPhone 4: the original Retina display The allure of higher-res screens is simple: more pixels should, in theory, mean a sharper, clearer, more detailed image – the effect Apple had with the iPhone 4 when it introduced the first ‘Retina Screen’. But improvement isn’t just as simple as sticking a higher-res screen in each new generation of phone: after a while, people will stop noticing the difference. This is because of one crucial factor: pixel density. This is a measure of how many pixels are packed into a physical area, normally measured in pixels per inch (PPI, not to be confused with the insurance you maybe owed money for, according to those irritating phone calls and adverts). Because smartphone screens are so physically tiny compared to TVs, the PPI is incredibly high – up to 530 on phones like the LG G3. Although that might sound like improvement, the human eye stops being able to make out a screen’s individual pixels after a certain point – and after that point, increasing the resolution further won’t really do anything of benefit. According to Apple, that cut-off is 326 PPI for a smartphone. (Your eye’s ‘max’ PPI depends on how far away the device is – hold press your face right up to a 4K TV, and you could probably see the individual pixels, but not so for a smartphone.) Experts, such as DisplayMate’s Raymond Soniera, peg that number a little higher – up to 600PPI for people with freakishly good vision. But either way, whether the magic number is 300 PPI or 600 PPI, 4K blows all those numbers away. On a standard 4.7-inch smartphone screen, a 4K display would give a resolution of 941 PPI, well in excess of anyone’s ability to resolve individual pixels. By that measure, 4K phone screens would be completely indistinguishable from 2K, or probably even Full HD screens. There’s other reasons to dislike higher-resolution screens, rather than just cost. The more pixels a phone has to generate, the harder its processor has to work, which means a hotter, slower phone that has worse battery life – not exactly a recipe for commercial success. There are, however, a few beacons of hope for the 4K smartphone screen. The first, and most often-quoted, is the rise of the phablet. Phablets have significantly larger screens than your average run-of-the-mill smartphone, so the 4K screen has more room to work its magic. More importantly, a hi-res screen offers companies a useful selling point: the LG G3 does technically have a sharper, crisper and clearer display than the Galaxy S5; it’s just the no-one would ever be able to tell the difference. That’s not to say that all small 4K displays are useless, however. The evolution of devices like the Oculus Rift have moved screens radically closer to our eyes, which means that a much higher-res screen is necessary (compared to a smartphone) to be able to get all pixels blurred into one. Pixel density: is the interest finally dying? There is, however, one small glimmer of hope that manufacturers will shy away from building 4K phones in favour of better battery life and cheaper component prices: the phone-buying public seems to be getting over its obsession with pixel density. Google Trends, a tool that lets you track a subject’s popularity on the internet, shows that interest in ‘pixel density’ has spiked over the last few years, but is slowly falling back to pre-iPhone 4-levels as PPI stops being a major selling point. Where does that leave 4K phones, then? Samsung and LG, two of the powerhouses of hi-def smartphones, have hinted in the past that 4K phone screens are a possibility, but have shied away from expressly stating they’re in the works. Most likely, then, 4K phones will be a reality in the next few years – but whether or not they’ll be a hit lies with the phone-buying public.