With the Apple tablet reveal less than a week away, it’s high time for me to engage in some idle speculation. The two questions on my mind are: what resolution is the tablet, and how will apps be made fit?
When it comes to the size of the tablet, there are three things I consider fixed:
- The iPhone has a resolution of 320×480 with a density of 163 PPI (points per inch).
- The resolution of 720p HD video is 1280×720.
- The tablet is widely rumored to have a 10.1-inch screen.
The third point needs to be taken with a pinch of salt, of course, but I’m not going to argue against it.
I’m going to assume that the tablet plays 720p video at native resolution. For a resolution of 1280×720 at a 16:9 ratio, a 10.1-inch screen has a density of 128 PPI. This seems reasonable, but I don’t think it’s quite right.
I think that the tablet is going to have the same 3:2 picture ratio as the iPhone. This will make it easier to port current apps to the tablet. Apple is also said to invest heavily into digital reading, and 3:2 seems a more comfortable ratio than the very wide (or tall) 16:9.
Let’s make the screen a little bit taller. The ratio is now 3:2 but native 720p video fits inside, letterboxed. This gives us a resolution of 1280×854. It may seem a little oddball, but Apple used to make PowerBooks with the same resolution. Density for a 10.1-inch screen is now 152 PPI, which is closer to the iPhone.
Resolutions of the iPhone, 720p video and my tablet estimate.
This is naturally all guesswork. A large high-density screen might be too expensive, or Apple might opt for a more common resolution for the sake of mass production. Still, this is my best guesstimate.
What about apps, then? I’m taking it as given that Apple is making a custom UI for the tablet and not running standard OS X applications. They’ll also want to have apps quickly, so repurposing existing iPhone apps make sense.
The tablet has several times the screen real estate of the iPhone – seven times as much in my estimate. I doubt that Apple is going to implement windowing on the tablet, so apps have to be made to fill up the screen.
The simplest solution is to scale up existing apps – made much easier if the tablet has the same image ratio. It’s a stopgap method only, as blowing up the interface is going to provide a poor experience in most cases.
The buttons from Twitterrific appear gigantic at tablet sizes.
Apple has been working on density-independent interfaces for years. Existing apps might automatically benefit from this through bigger, native-resolution fonts and controls. Any bitmaps, however, will appear jagged or blurry after zooming.
A bigger problem is that enlarged versions of small-screen interfaces make little sense. Elements will be uncomfortably large, and any touch gestures will have to be scaled up as well. It’s a different thing to swipe across a phone screen or a tablet.
Developers are going to want to tailor their apps for the tablet, and for that they need a UI toolkit. The UI conventions of the iPhone and the Cocoa Touch library are made for a phone-sized device. When kept the same size but spread across a bigger screen, they appear ridiculously sparse.
A mockup of the current iPod app adapted to tablet size, clearly not viable.
What new UI elements could Apple provide? Some obvious choices are Cover Flow and a tablet-friendly version of the grid views in iTunes and iPhoto. A version of the column view from Finder could be used in place of hierarchic lists.
On a higher level, tablet apps don’t need to consist of tiny screenfuls at a time, like iPhone apps do. There will be less navigation and more context – more onscreen at the same time.
All of this is known to Apple, and they’ve no doubt been busy at work creating new interface conventions for the tablet. They have to present an easy way for developers to shift into the tablet without dragging in too much of the phone or the desktop. It’s a tall order.
I can’t wait until Wednesday.