⇥ On the iPad’s Retina Display

As the time when everyone expects Apple to make its next move in the iPad game approaches, there is much speculation making its way through the technology circles—ably covered by John Gruber—on whether the next iteration of the Magical Tablet will, in fact, sport a high-resolution display.

First of all, I want to point out a couple of flaws in the conclusions that a number of analysts have reached in trying to figure out whether a Retina display is technically possible.

Resolution

The obvious resolution for an iPad Retina display is quadruple the current one, going from 1024×768 to 2048×1536 pixels, taking a page from the book of the iPhone, which undertook a similar change with the introduction of version 4.

However, this only makes sense because it’s the choice that Apple made with the iPhone. The iPad has considerably different display requirements, both because people use it in a different way (i.e.: staying further away from the screen, which reduces the pixel density required to obtain the fabled 300DPI Retina resolution), and because it’s based on a completely different form factor (4:3 compared to a rather odd 1.5:1 for the iPhone).

The question of whether doubling both vertical and horizontal resolutions results in better scaling is highly debatable; with reasonable filtering, Apple could go to any resolution and maintain excellent picture quality. For example, see this screenshot‘ of the upcoming iPhone version of The Funnies scaled by a factor of 1.5, compared to the same scaled to a factor of 2. There is, essentially no difference in the quality of the two pictures—they both look fuzzy because of the scaling, but from a developer’s perspective it would be just as easy to design interfaces at 2x as it is at 1.5x.

“But wait,” you’re saying, “fuzzy images look horrible. Why would Apple go with that?” The answer is simple: because it’s the responsibility of the developers to make their apps look good. Apple uses this technique right now—for example, when you run an app that is not Retina-ready on an iPhone 4, or when you run an iPhone app on an iPad at 2x. Look fuzzy? You bet. Even at 2x.

The real question here is one of convenience for Apple. Scaling to a factor different from 2 might be challenging for the GPU, for example (though, personally, I doubt it)¹.

Aspect ratio

The most bizarre analysis I’ve seen comes from those who somehow manage to link the problem of resolution independence to that of aspect ratio, claiming that, should Apple decide to make the iPad widescreen, it would be forced to either stretch the image or resort to letterboxing and rendering apps at a smaller size to account for the screen’s higher resolution.

The two things are not related in the way the article seems to imply. Were Apple to go with a widescreen aspect ratio, the proportions of the resulting image would obviously change. Therefore, stretching an existing 4:3 image to a widescreen resolution would result in a grossly distorted image; forget the fuzziness—everybody would look like they’ve eaten a stick of dynamite and blown up.

I don’t know that Apple would change the aspect ratio of the iPad; I suspect that a wider device of the same size would be harder to hold. Still, if they wanted to do that, they could solve the problem of widescreen stretching by letterboxing the resulting image. If the resulting image were of a higher resolution that the plain-old iPad, they can simply scale it accordingly. Thus a combination of scaling and letterboxing, the problem would be promptly solved without any significant degradation in usability.

“But wait,” you’re saying, “letterboxing current apps would leave awful black bands on either side of the screen, and possibly make them fuzzy. Why would Apple go with that?” Leaving aside the fact that Apple already goes with that ², it would, once again, be up to developers to make their app widescreen-compatible ³.

Cost

Cost is the most likely reason against Retina making it in the iPad two. Even then, though, the chasm to cross is not quite as wide as I initially thought. Consider that the retail price for a 15″ QXGA screen is around $500, and it’s not inconceivable that Apple might be able to rustle something that meets its pricing requirements for the iPad⁴.

Power

With these minor technical matters out of the way, I think that there is one overriding issue that Apple needs to address, and that’s the fact that, compared to the iPhone, the iPad is rather underpowered.

Consider that the iPhone 4, which has roughly 80% of the pixels of the iPad, shares the same GPU and has twice the RAM of its larger cousin. Considering that all graphics on the iPad are larger than the iPhone’s and take up considerably more memory, if I had to pick one thing to improve would be doubling the RAM to 512MiB, thus matching the iPhone 4.

The other issue to consider is one of packaging. The iPad’s current design, with its aluminum construction and curved back, belongs more with Apple’s iOS devices of old than the newer, slicker iPhone 4. I, for one, would love an iPad that doesn’t wobble on the table while you’re busy with a two-player game.

Finally, there are other hardware considerations in play—for example, the lack of a camera. Uncharacteristically, Apple has some catching up to do in this area: even the first iPhone shipped with one.

For these reasons, I think the most likely outcome will be an iPad 2 with better design and minor technical advancements like a camera and more RAM, followed by an iPad 3 with a Retina display down the road. On the other hand, I’m used to being surprised, and look forward to eating my hat if I’m wrong.