Reports have Apple preparing to introduce MacBook Pros withhigh-resolution Retina displays like the iPhone and iPad. How doesthe technology work, and can it revolutionize the desktop computingexperience? Apple raised eyebrows when it introduced the iPhone 4 with itsso-called "Retina" display. Although many dismissed thescreen as a gimmick, once folks set eyes on one it was hard not tonotice image quality and the readability of text on the iPhone 4was often superior to anything on the market. Apple stuck with theRetina display with the iPhone 4S, and then upped the ante againwith the third-generation iPad, which features a 9.7-inch LCD panelwith a 2,048 by 1,536-pixel resolution something that would havebeen unthinkable only a few years ago. Now, reports (such as those from 9 to 5 Mac have Apple readying a new MacBook Pro line with 15-inch displayssporting a 2,880 by 1,800-pixel resolution a screen twice asdense as current models.
What's the big deal about so-called Retina displays? Do theyhave the potential to revolutionize the desktop computingexperience the same way high-resolution displays have changed thepixel landscape for current iPhone and iPad users? The basic idea The essential idea behind Apple's Retina display has nothingto do with the particular technology used by a display. To date,Apple is using LCD screens, but the same ideas apply equally toAMOLED and even old-school CRTs. The premise is to increase the pixel density of the display beyond the point where the human eye candistinguish between individual pixels, meaning that images shown onthe display appear as smooth, continuous tones akin to ahigh-quality printed page, rather than a grid of colored dots. The idea isn't new: IBM has been offering high-densitydisplays for use with some of its top-drawer visualization andsupercomputing systems since at least the mid 1990s, and thingslike high-end flight simulators (particularly in the military) havebeen using technology like this for years.
The term Retina displayis an Apple invention hence the capitalization. A better term ishigh-density display, and even Apple uses terminology like that inits developer materials. Pixel density is usually measured in PPI pixels per inch which is a bit of a carryover term from theprint and broadcast industries, where dpi (dots per inch) is often used to describe resolution. At a verybasic level, the same idea applies to film photography, where"grainy" images can result from individual particles onthe film stock: enlarge a film image enough and you'll startto see the "dots," although they're not laid outon a regular grid like pixels.
With normal 20/20 vision, the human eye can resolve objects with anapparent size of about 1 arcminute * . For a sense of how small that is, there are 60 arcminutes to asingle degree and, of course, turning full circle covers 360degrees. The key here is apparent size, because objects appear to be bigger or smaller withdistance. We're all about the same distance from the moon, soit usually makes a reference object. The full moon (overhead, sayat midnight) is about 30 arcminutes across, or about half a degree.A human eye with normal vision can resolve objects about thirtytimes smaller.
(Yes yes, the moon seems bigger at the horizon: that's an optical illusion that hasn't been fully explained.) Here "resolve" means that we can actually distinguishthe object's shape and characteristics. Objects smaller thanone arcminute (with normal vision!) don't magically turninvisible and vanish from view: If there's enough contrast,we can still see them. But all we see is a dot: we know something is there, but can't distinguish much of anything about it.That spot in the sky might be a bird, might be a plane, might be aguy with his underwear on the outside his pants hurtling throughthe air. We won't be able to tell until it gets closer.
Doing the math So, how does the math on that work out? At a distance of 12 inches,the figures above mean a human eye with normal vision can resolveobjects about 0.0035 inches in size. For individual pixels on adisplay to be too small for the human eye to resolve at thatdistance, the display needs to be about 286 pixels per inch (PPI). Here's how some Apple products stack up: By way of comparison, the first Macs had screen resolutions of 72ppi (Windows systems varied quite a lot). These days, typicalscreen resolutions for notebook at desktop computers range fromabout 96 ppi to about 150 ppi.This math isn't new: it'sthe same logic that lead to the first commercially laser printersoffering "high-quality" output of 300 dots per inch(DPI).
Notice only one current Apple product exceed that 286 ppithreshold: the iPhone 4 and 4S. If Apple's forthcomingMacBook Pros do include a Retina display, it looks like it'llcome in at about 220 ppi. But 200 ppi could be just fine, because all things aren'tquite equal. First, most people don't consistently position adisplay exactly 12 inches from their eyes: Some people hold it alittle closer, many people hold them a bit further away, anddisplays on notebooks and desktop computers tend to be further awaystill.
Remember: the further away something is, the smaller itsapparent size. As an example, my desktop displays are about 34inches from my eyes; a notebook on a tabletop seems to be about 24inches. (Flipside, I'm sure by now most of us have seen folkswalking around with their iPhones nearly touching their noses.) Second, plenty of people don't have normal vision. Forinstance, I don't have any trouble picking out individualpixels on an iPhone 4S from about 18 inches at least, with one ofmy eyes.
The other eye doesn't do so well. It's easy toargue that folks who don't have 20/20 vision probably havecorrective lenses, so the same visual rules about being able toresolve individual pixels ought to apply but that's notreally true. Plenty of people don't wear their glasses orcontacts all the time, and plenty of people who don't have20/20 vision don't use corrective lenses at all. In theUnited States, folks typically only need about 20/40 vision to passa driving test.
All this means that screens with resolutions lower than 286 ppi canoffer a Retina-like experience for many users, they're eitherfar enough back from the screens, don't have perfect vision,or both. Memory, bandwidth, and resolution Observant readers will note two other columns on that table above:pixels and memory. It's easy for us to think of a displaymeasuring 2,048 by 1,536 pixels as having twice the resolution ofone measuring 1,024 by 768 pixels after all, each side is twiceas long. However, that translates to a four-fold increase in the number of pixels and that, in turn, directlytranslates to a four-fold increase in the amount of memory a devicehas to use and process to manage the current display. In loose terms, the device with the larger display has to haveabout four times the memory and be able to move data in and out of its graphics systems four timesfaster at least, if it wants the display to appear to perform aswell as the smaller version.
That means more reading and writingfrom memory, and that means consuming more power. So, particularlyon portable devices, manufacturers use processors and othercomponents that use as little power as possible. Again, all things aren't equal. The figures above may make itlook like a third-generation iPad only needs 9.2 MB of video memoryto manage its display and that would be true if the iPad werejust managing one image for the whole screen at any given time.(That's what the original personal computers did, by theway.) The reality of software development is that applicationsoften render and load up graphic elements in video memory so thingscan be displayed fast. Common examples include games (wherecharacters, objects, and other graphical elements get stashed invideo memory for real-time access) but also seemingly prosaicapplications like Web browsers: When you switch to a different tab,the page that just disappeared is probably still in video memory,ready to be re-summoned when you want it.
The same thing is true ofinterface elements like menus, buttons, and scrollbars, andhundreds of things we see on screen all the time. The impact of high-resolution displays is most apparent in theseelements. Let's say a typical application icon measures 128pixels square. On a display with 100 ppi resolution that icon ismore than an inch across, and very clear and visible to most users.Put that same icon on a display with a 200 ppi resolution, andsuddenly it's about a half inch square and occupies a quarter of the area it previously consumed.
The same effect applies acrossthe board: If you jam twice as many pixels into a display,everything on that display will appear one quarter the size it didbefore. That's a quick way to make applications (andinterfaces) completely unusable. Makes you squint So why didn't Apple's iOS become unusable when theytook the iPad and the iPhone to high-density displays? Theyincluded interface elements that were four times the resolution ofthe old versions their apparent size on screen didn'tchange, but their apparent quality did since they used four timesas many pixels to present their image. And yes, those elements takefour times as much memory and storage to manage.
Similarly,application developers who wanted to leverage the Retina displayhad to update their apps and that includes upgrading theirgraphics to four times the size of previous versions. The same thing will be true if (ahem, when ) Apple begins to introduce high-density displays to its notebookand desktop lines. Most existing applications will run just fine but they'll appear chunky in comparison to apps developedwith the high-density display in mind. Where an application mayhave drawn a line that was one pixel wide before, the high-densitydisplays will use two pixels. For some apps, this may not matter atall; for others, it might be a major eyesore.
There may be some apps that don't make the transition verywell. The most likely candidates are games that are doing sneakygraphics tricks possible candidates include games based onOpenGL, or other graphics engines that have had to do low-leveltweaks to interface with graphics hardware. Similarly, some imageand video editing apps may have performance issues or glitches the more dependent they are on interacting with graphics hardwareand drivers directly, the more potential for problems. Are high-density displays worth the hassle? Do high-density displays bring real benefits? The overwhelminganswer seems to be "yes." Consumers are voting withtheir feet and their money.
The third-generation iPad and theiPhone 4 and 4S have been astonishingly successful products forApple, and their displays have been almost universally lauded.Other mobile device manufacturers were quick to jump on thebandwagon: Samsung, HTC, Motorola, Sony, and LG have all releasedsmartphones with high-density displays many of which exceed theiPhone's density. (The Sony Xperia S and HTC Rezound seem to be currently tied for the top spot, with displaysoffering 342 ppi) but RIM seems to be gunning for over 350 ppiwith its next tablet.) However, it's important to note that high-density displayshave, so far, been limited to rather isolated ecosystems. InApple's case, the company's tight reins on the iOSplatform (and its sheer popularity) has helped ease the transitionto high-density displays. When the original iPad debuted, it wouldrun apps developed for the original iPhone, but they were seriouslyclunky compared to versions made specifically for the iPad.Developers quickly embraced the iPad, however, and similarly haveembraced the high-density displays on the iPhone 4/4S andthird-generation iPad. Android is another story.
While there are a number of Androiddevices that offer high-density displays, fragmentation means theyaren't seen anywhere near the same level of developer supportApple has commanded with iOS. Yes, people can buy Android deviceswith high-density displays, and yes, there are apps designed forthose displays. But persuading an Android developer to make ahigh-density version of their app can be a tough sell. If an appbenefits substantially from high-density displays, it might be ano-brainer. Otherwise, most Android developers are likely toconsider apps that target a wide range of screen resolutions to begood enough and if they look a little clunky on high-definitiondisplays, so be it.
Apple may experience something similar if (ahem, when ) it introduces high-density displays for Macs. The Macintoshsoftware ecosystem is nowhere near as tightly knit as the iOSecosystem, and is littered with legacy applications folks have beenusing for years and which may never be updated. Apple has made anumber of transitions that have forced its Mac OS X users toabandon legacy software such as killing off Classic in Mac OS X10.5 Leopard, and eliminating support for PowerPC applications inMac OS X 10.7 Lion. Apple is now making moves to lock down the MacOS X software ecosystem almost as hard as iOS: Apple'sforthcoming Mac OS X 10.8 Mountain Lion will drive all userstowards Apple's Mac App Store, and perhaps as soon as June1 apps won't be able to get into the store unlessthey're limited to a security sandbox.
It's reasonableto assume explicit support for high-density displays will soon beconsidered a key feature. Microsoft will have a much tougher time with high-density displaysdue to the vast ecosystem of legacy Windows software that'sin active use. Microsoft is in a very strong position to takeadvantage of high-density displays with the brand-new Windows Metro(particularly on Windows RT for ARM-based devices) but will likelyhave a tougher time convincing budget-sensitive customers dependenton legacy software for the traditional Windows desktop to step up.Plus, the ever-frustrating dance many Windows users perform withvideo drivers, BIOS, and applications will carry forward tohigh-density displays. But gosh: when it's all over, won't everything be sopretty? * There are varying definition of "normal" vision.Optometrists often define normal 20/20 vision as the ability todistinguish letters that take up five minutes of arc; however, somedefinitions of normal vision include distinguishing objects with anapparent size as small as 0.6 arcminutes. I am an expert from Apparel, usually analyzes all kind of industries situation, such as warmest winter coat , fruit puree suppliers.
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