2272 x 1280 or bust?
Similar to the "2048 x 1536 or bust" thoughts in the run up to the "retina" iPads, a lot of people are wondering what resolution Apple will use on a hypothetical large screen iPhone. I think it is 2272 x 1280 or bust.
During the interview with the WSJ, Tim Cook says this:
WSJ: People want a bigger screen iPhone. Are you against that?
Cook: What we’ve said is that until the technology is ready, we don’t want to cross that line. That doesn’t say we’ll never do it. We want to give our customers what’s right in all respects – not just the size but in the resolution, in the clarity, in the contrast, in the reliability. There are many different parameters to measure a display and we care about all those, because we know that’s the window to the software.
"until the technology is ready"
I interpret that to mean when 2272 x 1280 screens meet Apple's standards for mass production (cost and capacity), power characterisitics, and screen quality. This resolution is the best of all possible worlds for a hypothetical iPhone with 4.7 to 5.7 inch displays. For a 4.7" disp, 2272 x 1280 results in 555 DPI. At 5.7", it is 458 DPI.
Software-wise, it'll be just as before with the transition to 960x640 from 480x320, the existing apps will run pixel-doubled without any loss in sharpness. Developers who want to take advantage of the screen res can simply increase the size of their bitmap assets as before. I presume fonts will be automatically rendered at the higher DPI. It'll be a very seamless transition for users.
For Apple, it maintains the iPhone's brand as a premium handset with premium prices. Gruber, Arment and others are thinking Apple will be fine with 1136 x 640 on a 5" display, but I don't see how it can really work that way. I can't think of a good marketing or branding strategy for it. In addition, users will perceive jaggies on fonts and lines at 264 DPI (1136x960 at 4.94" diag), and I think it will perceptively degrade the brand, especially for the price of new iPhone. The only way Apple can do it is if the display offers some other functionality, more advantageous than the higher DPI, like solar, sunlight readability or super long battery life.
GPU-wise, Apple's existing A7 GPU drives the 2048 x 1536 displays in the iPad Air/mini, and a prospective A8 GPU that is 1.5x to 2x more powerful represents only a little bit of a regression in perf/pixel for an iPhone with 2280 x 1280. If the A8 SoC has improvements in memory bandwidth, L3/L4 cache, and CPU, even better.
The user benefits will be smaller than the previous doubling in DPI for iPhones, almost 4 years ago, but it is an incremental advance that I think Apple will take. The question is "until the technology is ready". There were lots of ~450 DPI panels shipped in 2013. 2014? It feels tantalizingly close.