In late November Qualcomm (NASDAQ: QCOM) announced that the next-generation of its SoCs would have the processing power to push out a 4K resolution on a smartphone. This would be a jump from the existing QHD (quad HD, 2560×1440) resolution that’s found on the displays of high-end smartphones currently on the market.
While 4K certainly has its uses and benefits on larger displays, the potential use cases on such a small smartphone screen are negligible at best. On an average smartphone screen, which is usually around 5.5-6 inches, the resolution of QHD — let alone 4K — is too great for the eye to appreciate. Apple’s Retina display has a pixel-per inch density of 326. A QHD display on a smartphone would equal something in the range of 538.
A PPI of 538 is far beyond the maximum resolution that the human eye can recognize. There is a bit of controversy as to what the highest practical PPI is for a 5.5 inch screen held 12-18 inches away from the eye, but the consensus holds that it’s 477 PPI at 12 inches and 318 PPI at 18 inches. Of course, holding it closer than 12 inches away from your face would make it difficult to properly focus.
So this means that the iPhone’s Retina resolution introduced in 2010 is the highest practical resolution for a smartphone sized screen. Of course with bigger screens found on phablets and full-on tablets this figure jumps.
QHD and 4K smartphones are impractical
The other issue with QHD and 4K displays on smartphones is the substantial battery drain that comes as a result. Battery technology has reached a ceiling, yet the demands keep on increasing. A QHD or 4K screen requires substantially more push from the SoC to drive a screen of that resolution, which means the SoC will require more battery power for all tasks.
“4K needs a lot of power, so if you use it you have to make compromises. A 4K display on a smartphone may give you half a day of battery life but a 2K display can give you maybe one day or more,” President of the Handset Product Line Kevin Ho is quoted as saying. “4K has four times the pixels of Full HD so the power consumption is maybe 4 or 8 times as much as Full HD so the smartphone has to have compromises with battery life.”
All about competition
Pushing up the resolution of smartphone displays is not the only way to improve the quality of the screen. There’s much to be done to improve color depth, backlight quality, and the ability for the screen to display in bright conditions.
But the resolution race is a way for vendors to compete with each other. The screen resolution of a device is an easy and digestible metric to understand. But for consumers this resolution race isn’t, in the end, a value add as it does little to increase productivity or performance.