The Resolution Gap

Mark Fihn in High Resolution, Veritas et Visus:

With the exception of the prodigious marketing power that Apple brings to the market, there really is no difference between the need for high resolution displays and what faced the market a decade ago. Quite simply, so long as the display in front of us fails to match the visual imagery created by our visual system, there will be a need for improvement. Resolution is perhaps the single biggest performance parameter that today leaves us with a gap when it comes to our eye’s ability to perceive visual images. So long as that gap exists, it’s easy to predict that displays will improve in terms of pixel density.

Resolution, or pixel density, was Apple’s focus on the iPhone 4 with the 3.5-inch IPS LCD Retina Display. There has been recent rumblings suggesting that Apple is working to apply the Retina Display brand on its other offerings like the MacBooks and iMacs. There were HiDPI display modes that were found in a version of OS X Lion. Eric Rucker, a DisplayBlog reader, developed a neat Retina Display calculator that gives you the minimum viewing distance and pixel density.

The most recent iPod touch also sports a Retina Display with the same pixels per inch as the one in the iPhone 4 but everything else was sub-par: poor viewing angles, dramatic color and brightness shifts, etc. Unfortunately the definition of Retina Display in Apple’s case depends on only two things: pixel density and the distance at which you’ll be viewing the display. There isn’t a quality requirement. Let’s hope Apple fixes this and put a proper Retina Display in the iPod touch.

Fihn’s prediction that display pixel density will continue to improve as long as a resolution gap exists between the display and our eyes will no doubt turn out to be true.

The reason why it has taken so long for high pixel density displays are many. From having worked at LG Display it is much more difficult to manufacture a high resolution display than one with less. High resolution also means high price. There is also the fault of Microsoft, Apple and any other company that develops operating systems. There hasn’t been an OS that took advantage of higher resolutions to improve clarity, instead higher resolutions meant larger screen real estate in terms of pixels, but also tiny icons and text. Without proper support from OSes there was a limit to how many pixels you could cram into a LCD: it was the simple problem of users not being able to comfortably view stuff on high-resolution displays.

iOS was the first OS to properly make use of high resolution displays. But it took a company that had complete control over hardware and the operating system. There was a single display: 3.5 inches with 480×320 pixels in landscape. The resolution was 163 ppi. Apple doubled the pixels both horizontally and vertically to 960×640, doubling the resolution to 326 ppi. Apps that ran on the iPhone 4 weren’t a quarter of the size, which is would have happened on other OSes, but instead were four times as clear.

I believe this is what will happen with the next version of the iPad. Let’s call it iPad 3. As far as I know a 9.7-inch LCD with 2048×1536 pixels has been under development for quite some time. It isn’t easy to cram so many pixels and make the display perform well. Remember Big Bertha by IBM? The model name was T210 and the 22.2-inch LCD monitor sported a pixel format of 3840×2400. The resolution was a world-leading 204 ppi. The specs looked great, but because the underlying thin-film transistors (TFT) didn’t work fast enough Big Bertha had flicker, which made it less-than-usable.

Another notable display was the 30-inch Cinema HD Display with a 2560×1600 pixel format. The pixel count was high, but the resolution was just under 101 ppi. Still pushing electrons fast enough on such a big display was an engineering challenge. Apple worked with LG Display and the South Korea-based LCD manufacturer developed TFTs made of copper, which allows for faster electron mobility. As a result there was no flicker on the massive 30-inch Cinema Display, which was quite usable but the high price made it a tool for only those well funded.

Apple is again working with LG Display for an iPad Retina Display. Samsung, Toshiba, and Sharp might become additional suppliers of the display. The TFT will most likely be made of copper or some other material that will allow for electrons to move about rapidly so that all 3.1 million pixels (2048×1536) on the 9.7-inch IPS LCD update flicker-free in response to our multitouch gestures. No doubt this Retina Display will be expensive but I believe Apple will be able to bring down the overall bill of materials so that we’ll see a starting price of US$499 for the iPad 3. Just as important as the hardware developments is the fact that iOS will take 4x the pixels and make text and everything else more clear, instead of small.

It is no secret that Apple is importing features of iOS into the next version of OS X called Lion. The thing that isn’t so clear is when. Will we be seeing HiDPI display modes and therefore Retina Displays on MacBooks and iMacs in Lion?

Integrating a Retina Display into MacBooks, iMacs and Cinema Displays won’t be as simple as putting a Retina Display on iOS devices. Apple has many displays that it needs to work with. Let’s focus on MacBooks: there are currently six display variations and corresponding resolutions are quite dispersed:

  • 11.6-inch 1366×768: 135 ppi
  • 13.3-inch 1280×800: 113 ppi
  • 13.3-inch 1440×900: 125 ppi
  • 15.4-inch 1440×900: 108 ppi
  • 15.4-inch 1680×1050: 129 ppi
  • 17.0-inch 1920×1200: 133 ppi

In a future update Apple will most likely drop the 13.3-inch 1280×800 and 15.4-inch 1440×900 bringing down the variations from six to four, which is more manageable. At a viewing distance of around 18-20 inches, similar to but slightly farther than the iPad, the MacBooks will require a resolution of around 180-190 ppi.

The 17.0-inch MacBook Pro will then need to have a 2560×1600 pixel format, which we saw on Apple’s 30-inch Cinema HD Display, to get to a Retina Display level. Current LCD manufacturing technologies are able to produce this level of pixel density. Here’s the list detailing pixel formats, resolutions, and minimum distances to the display for a retina effect:

  • 11.6-inch 1920×1080: 190 ppi, 18.1 inches
  • 13.3-inch 2160×1350: 192 ppi, 18.0 inches
  • 15.4-inch 2400×1500: 184 ppi, 18.7 inches
  • 17.0-inch 2560×1600: 177 ppi, 19.4 inches

The general tendency is to have larger displays farther back, but I’ve also taken into consideration likely pixel formats that the LCD manufacturers would consider. The bottleneck isn’t technology but price. But someone has to start the process: the cost of manufacturing will not come down until a company like Apple works with a LCD manufacturer like LG Display to make large Retina Displays, eventually producing them in volume leading to lower costs.

When this ball will get rolling is anyone’s guess, but we will eventually get to Retina Displays on MacBooks. And that’s when the resolution gap between displays and our eyes will be closed.