i've never really been one to add grist to the rumormill, but i've been intrigued by the recent speculation over what the dimensions of the next generation iPhone screen will be, both in pixels and inches. i had an idea about this on my own last week, even before i knew that this was a hot topic. the coverage of the topic on Hypercritical e64 introduced me to the current theories. if you want to be totally up to date, go read all the posts in that episode's show notes; if not, i'll summarize briefly along the way. there are two prevailing theories, but i'd like to add a third.
theory #1: the stretched "16:9" iPhone
this is the theory posted on The Verge and "corroborated" by John Gruber. the notion is to keep the horizontal resolution and size of the screen fixed at 640px and 1.94 inches, but to streeeeetch the vertical resolution. the original theory was to take it to 1152 px to achieve the magic 4 inch mark, leaving the screen with a somewhat awkward 9:5 ratio. there are lots of aspect ratios on the Wikipedia uber-doom-chart of screen sizes (including 17:9!), but 9:5 isn't one of them.
when The Russians Used a Pencil picked up this idea and ran with it, they just assumed that the stretched iPhone would have a 16:9 native ratio (instead of the somewhat ridiculous 7px pillarbars that would result in showing 16:9 content on a 9:5 version). one problem: 640 isn't divisible by 9. that leaves a bit of a quandary. either Apple goes into totally new aspect ratio territory with a stretched screen, or has to alter both dimensions to get true 16:9.
theory #2: just blow it up
the other prevailing theory is to leave the pixel resolution of the screen untouched, but just make it bigger, and therefore less dense. people are quick to note that Apple left itself fudge factor to take the resolution down to 300 ppi without having to alter its marketing definition of "Retina Display". (given the "hey, remember trig from high school?" earnest excuses for the 3rd-gen iPad's pixel density, i don't think this is something Apple wants to compromise on, either.) doing a strict scale to 300 ppi would push the diagonal measurement to ~3.80 inches. not bad, but not exciting either.
theory #3: emulate the iPhone's big brother
here's my idea which, as far as i know, hasn't been entered into this discussion. (if i've just missed it, i don't mean to step on anyone's toes. and please do send me any links you find.) the foundation of the stretch theory is that it's easy to keep manufacturing screens at the same ppi — apparently it can be done on the existing equipment. if that's the case, why cut panels that are wacky new aspect ratios? how about a 1024 x 768 (a.k.a. XGA) panel?
does that number sound familiar? of course, it's the pixel dimensions of the original iPad. but what would turning the iPhone into a mini-iPad achieve? first of all, the physical dimensions. preserving the 326 ppi density, the screen would have a diagonal measuring ~3.93 inches, which does better than theory #2. in terms of pixel dimensions, it would be a gain of just over 172K pixels, or an increase of 28% in screen real estate. that's a pretty good boost, especially compared to the 20% uni-directional boost of theory #1.
the question is whether taking the cue for the next iPhone screen from the iPad gains anything other than pixels. i have no fancy mockups of case designs or interfaces (as demonstrated by the above size comparison graphic), but i think it's fairly safe to say that the iPad has proven that running iOS on a 4:3 ratio screen has been a success. a major qualm about a 16:9 screen is whether it would be possible to do anything but watch video in landscape mode, short of having to design one-line text input interfaces. but i do see benefits beyond just having a squatter shape.
- developing from iPad ⟶ iPhone some developers would be able to take existing iPad art assets and drop them directly onto the iPhone. this is obviously a no-go for applications with complex interfaces designed to take advantage of the iPad's physical size — slowly do the five-finger pinch gesture on TweetBot for the iPad and watch how as it scales down, the tweets are perfectly legible but the buttons become an un-tappable size. however, some have surmised that games would have the most art to redo to accomodate a naive aspect ratio, but most games already have 4:3 assets and code for iPad.
- developing from iPhone ⟶ iPad iPhone developers reluctant to put a lot of time into a dedicated iPad version (either in the form of a separate app or separate code in a universal app) are second-class citizens. the 2x mode of scaling iPhone apps looked bad enough on the first two generations of iPads, and it looks comical on the 3rd generation. but, as many who got launch-day 3rd generation iPads noticed, non-retina iPad apps looked pretty damn good with pixel-doubling and native text scaling. blurring the line between iPhone and iPad apps has its pros and cons, as does forcing active developers to have a 4:3 interface and assets. however, it may push iPhone users ambivalent about buying an iPad over the line if they know that all of their purchased apps will look good on their new device. Apple is trying to drive hardware sales, and with iPhones saturating the market as much as they have, this is the currently operational halo effect.
- unification, not fragmentation it seems more than fair to presume that Apple doesn't want to introduce another aspect ratio to the iOS universe. taking a cue from the iPad for a new iPhone would accomplish that, and could even reduce the total number of aspect ratios to just one within a couple hardware generations. the question then is more a matter of taste: is 4:3 really the aspect ratio of the future, and not an aspect ratio of the past? for devices that primarily operate in portrait orientation, i see no reason why it couldn't be.
those are my thoughts. it seems just crazy enough that Apple would consider it. i suppose in a couple months i'll know how wrong i was.