The Display

The most visible improvement of the new iPad is naturally its Retina Display. Originally introduced with the iPhone 4, the concept of an Apple Retina Display was created to refer to a display where the pixel density was high enough that the human eye, at a standard viewing distance, could not resolve or identify individual pixels.

Unlike traditional OSes, iOS doesn't support a laundry list of display resolutions. The iPhone was introduced at 480 x 320 (3:2 aspect ratio), while the iPad came to be at 1024 x 768 (4:3 aspect ratio). Rather than require iPhone applications be redesigned for a higher resolution iPhone, Apple simply doubled both the vertical and horizontal resolution for the iPhone 4—maintaining the same aspect ratio as the previous models, and only requiring higher quality assets, not a redesigned UI, to take advantage of the new display.

The iPad on the other hand always required a redesigned UI to make the most of the iPad's larger display and higher resolution. With a different aspect ratio, simply scaling up an iPhone app wouldn't work (although to enable backwards compatibility Apple did allow you to do just that). Admittedly Apple wouldn't want to allow such easy portability between iPhone and iPad apps as it wanted the extra effort to improve the quality of tablet apps.

The new iPad does what the iPhone 4 did and doubles both horizontal and vertical resolution: from 1024 x 768 to 2048 x 1536. All iPad applications work by default as developers don't directly address pixels but rather coordinates on the screen. Existing apps take up the full screen, and if higher resolution images are present they are used as they avoid the interpolation associated with scaling up an image designed for the original iPad resolution. For example, below we have a makeshift iOS icon in three different forms—10x7 native (72x72), upscaled to a 2x version using bicubic interpolation (144x144), and a 2x resolution version (144x144):

72x72
144x144 (Upscaled)
144x144 (Native)

The upscaled form looks good, but the 2x resolution version looks better.

More traditional OSes have always given you additional desktop real estate with increased resolutions. iOS simply gives you a better looking desktop. This distinction is arguably one of the reasons why the new iPad's display can be so polarizing. As consumers of high-end displays we're used to higher resolution going hand in hand with a larger panel size. Alternatively, we're used to a higher resolution enabling us to see more on a screen at one time. In the case of the new iPad, the higher resolution just makes things look sharper. It's a ton of work for an admittedly more understated impact, but it's the type of thing that simply had to be done.

Retina Display Enabled Apps

Apple has created such a healthy marketplace with the app store that developers are eager to quickly deliver apps with updated graphics for the new iPad. Sure enough, by the day of launch we saw several high profile applications with higher resolution assets for the new iPad. The motivation to have Retina Display support is huge as Apple is actively promoting those apps that have been updated for the new iPad via the app store:

These updated apps now come with larger image assets, which can increase the total app size. Not all apps will grow in size (e.g. Infinity Blade 2 simply renders at a higher resolution vs. using tons of new content, not to mention that textures are already heavily compressed) but some have/will. The retina burden unfortunately impacts all iPads as there's only a single app package delivered upon download. Even if you don't use them, the higher resolution retina graphics are there.

Note that iPhone apps will now load their Retina assets (designed for 640 x 960) rather than their normal assets (designed for 320 x 480) on the new iPad, resulting in a significant improvement in image quality there as well:

Games are a special exception to the 2x asset scaling of the new iPad. Applications that simply have their UI accelerated by the A5X's GPU do fairly well at the iPad's native resolution. 3D games are another story however.

If all you're doing is determining the color of a single pixel on the screen, not impacted by lights in 3D space or other transparent surfaces above the surface, it's a relatively simple and painless process. For the majority of what you're looking at in iOS, this is simply the procedure. The app instructs the drawing APIs to place a red pixel at a set of coordinates and that's what happens. In a 3D game however, arriving at the color value of that pixel can require quite a bit of math, and quite a bit of memory bandwidth.

Game developers have a few options on the new iPad. One option is to not update a game, running it at 1024 x 768 and rely on the iPad's scaler to upscale the image to 2048 x 1536. The game will take up the full screen, run faster than on the iPad 2, but it won't necessarily look any better. Low resolution content upscaled to a higher resolution display still maintains much of the aliasing you'd see at a lower resolution.

Another option is to render all scenes at the new iPad's resolution: 2048 x 1536. With four times the number of pixels to fill and only 2x the compute and memory bandwidth compared to the iPad 2, this will only work for fairly lightweight content. Not to say that it's impossible—even GLBenchmark's Egypt test, in its current form, actually runs very well at the new iPad's native resolution. Many stressful 3D games won't fall into this category however.

The third, and more popular option is for a game developer to render all frames offscreen at an intermediate resolution between 1024 x 768 and 2048 x 1536, then scale up to the panel's native res. So long as the developer maintains aspect ratio, it'll be possible to use this approach and get a good balance of higher resolution and performance.


Infinity Blade 2 for the new iPad Renders at roughly 1.4x the iPad 2's resolution, then upscales to fill the screen

Infinity Blade 2, for example, renders offscreen at roughly 1.4x the resolution of the iPad 2 before scaling up to 2048 x 1536 for final display. The result is a sharper image than what you'd get on an iPad 2, without sacrificing performance.

Game developers may choose to increase the level of anti-aliasing instead of or in combination with an increase in resolution. As we'll discuss shortly, Apple's A5X does come equipped with more GPU execution resources and dedicated memory bandwidth for graphics that would allow for an increase in quality without a corresponding decrease in frame rate.

The new iPad The Display: In Numbers
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  • Jamezrp - Wednesday, March 28, 2012 - link

    Didn't want to cause Verizon too much trouble? Heh, very funny. I am amazed at how the iPad ends up being an amazingly good Wi-Fi hotspot. It almost seems like business users should opt to get an iPad for that function alone. I know plenty of people who would be happy to keep it in their bag, with the hotspot feature enabled constantly, while travelling about. Even for the price there is nothing even close that can compare.

    Plus, you know, you get the tablet too.
    Reply
  • supertwister - Wednesday, March 28, 2012 - link

    "It’s a quantum leap from the noisy, 0.7MP mess that was the iPad 2 camera."

    Interesting choice of word considering a quantum is the smallest possible division for a quantity...
    Reply
  • omion - Wednesday, March 28, 2012 - link

    Quantum leap:
    (n) an abrupt change, sudden increase, or dramatic advance

    The phrase comes from the ability of particles to make a sudden jump between two energy levels. It is a leap (of any amount) between two quantization levels, not a leap of the smallest possible amount.
    Reply
  • drwho9437 - Wednesday, March 28, 2012 - link

    A large fraction of the die doesn't seem to have a known use? Wondering what could be taking up all that area if not GPU, CPU and memory interfaces/caches... Most other I/O would have small footprints... Reply
  • tipoo - Wednesday, March 28, 2012 - link

    The 4S had a larger than usual die for its voice cancellation features that were needed to make Siri work well, the iPad does't have that but it does have voice dictation so some space is probably for that. Reply
  • PeteH - Wednesday, March 28, 2012 - link

    A big chunk of it is probably the ISP they talked about when the 4S debuted. Reply
  • Lucian Armasu - Wednesday, March 28, 2012 - link

    So this is how I assumed. The new iPad is in fact slower than the iPad 2, if games actually start using the 2048x1536 resolution for their apps, which everyone seems to be encouraging them to do. But once they do that the graphics will either look poorer, or they will be slower than they were on the old resolution, even on an iPad 2.

    Add that to the fact that apps are much bigger in size with the retina resolution, and the CPU is the same as last year. The new display might look great, but it's obvious that the new iPad is absolutely a step-back in terms of performance, whether it's GPU or CPU we're talking about. Hardly worth an upgrade, especially for iPad 2 owners.
    Reply
  • xype - Thursday, March 29, 2012 - link

    Blah blah blah performance blah not worth it.

    I don’t give a shit about theoretical performance that I might be getting if DNA folding software was available for tablets. I really, really give a shit about being able to read website and ebook text without my eyes straining after an hour.

    One would think that 10 years after "No wireless. Less space than a nomad. Lame." and Apple raking in millions and billions of profit, those Geek Metrics™ that people are so fond of here (nothing wrong with that, it’s interesting stuff!), would be recognized as completely and utterly worthless to the average population. But apparently not.

    The iPad was never ment to replace PCs and Consoles as a hardcore gaming device, and it was never ment as a render farm server replacement. It would be really nice if people realized that, at some point. In the next 5 years, perhaps.
    Reply
  • tipoo - Thursday, March 29, 2012 - link

    It seems a bit like the 3GS-4 transition, it used the same GPU despite higher resolution and so performed worse at native, although in this case the CPU is unchanged and the GPU is "only" 2x better for 4x the pixels. Developers got around that on the 4 by making games for the old resolution and using upscaling mode. I'd imagine they will do the same here once games hit the limits of the GPU at native. Games like Infinity Blade 2 also use separate resolutions for things like the menus vs shadows vs terrain textures. Reply
  • darkcrayon - Thursday, March 29, 2012 - link

    I guess if the only thing you bought an iPad for were games, and you could only consider a game to be worthwhile if it were drawn directly at 2048x1536, you'd have a point. But of course the new iPad could play games at the "iPad 2" resolution at much higher detail, or at a slightly resolution with the same detail, etc.

    It doesn't make sense to say it's a step backward in performance overall- it simply has the option to display much higher resolution graphics that the old model didn't have. The iPad 2 displays 2048 x 1536 text at "0 mhz" so to speak. It's not like you are losing anything by having the option of ultra high resolution if the type of game (or app) can use it within the hardware capabilities.
    Reply

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