iPhone Retina display sparks resolution argument

It’s not every week that Apple ignites a controversy. Okay, maybe that’s not true, but it’s not every week that Apple ignites a controversy that pits physicists, astronomers and neuroscientists against one another. But that’s what happened with the introduction of the iPhone 4 and its high-resolution Retina display.

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It’s not every week that Apple ignites a controversy. Okay, maybe that’s not true, but it’s not every week that Apple ignites a controversy that pits physicists, astronomers and neuroscientists against one another. But that’s what happened with the introduction of the iPhone 4 and its high-resolution Retina display.

During his keynote at this year’s Worldwide Developers Conference, Jobs tried to explain just how impressive the resolution of the iPhone 4’s new 326-pixels-per-inch Retina display really is:

It turns out that there’s a magic number right around 300 pixels per inch, that—when you hold something around 10 or 12 inches away from your eyes—is the limit of the human retina to differentiate the pixels. And so they’re so close together when you get at this 300 pixels per inch threshold, that all of a sudden things start to look like continuous curves… Text looks like you’ve seen it in a fine, printed book. [It’s] unlike anything you’ve ever seen on an electronic display before. At 326 pixels per inch, we are comfortably over that [300 pixel] limit.”

After the event, our live coverage team of Jason Snell and Dan Moren got to look at the real, live device. They wrote:

We couldn’t pick out any pixels on the iPhone 4’s text; as Apple claims, this screen really makes text look like something you’d find in a book or a magazine, with none of the artifacts that we’ve come to expect from a LCD display… Photos and videos are absolutely spectacular on the iPhone 4. It really is like looking at a self-illuminated photographic print, not a computer image.

 Daring Fireball pundit John Gruber also got to meet the iPhone 4 in person. He wrote: “The resolution of the ‘retina display’ is as impressive as Apple boasts. Text renders like high quality print.”

So is seeing believing? This is where it gets sticky. Wired’s Brian X. Chen, who was also present at the Apple event and saw the device for himself afterward, wrote a piece with the surprisingly definitive headline, “iPhone 4’s ‘Retina’ Display Claims are False Marketing.” The story’s lead sentence: “The iPhone 4’s screen may be the best mobile display yet, but its resolution does not exceed the human retina, as Steve Jobs claims.”

Wired’s confident claims that Steve Jobs was fibbing were apparently the result of a single source: a physicist named Raymond Soneira, the president of DisplayMate Technologies. According to Chen, Soneira has studied displays for 20 years. Soneira told Chen: “[The iPhone 4’s screen] is reasonably close to being a perfect display, but Steve pushed it a little too far.”

Soneira objected to Jobs using pixels as a measurement of eye resolution in the first place, because eyes use something called angular resolution, while a flat display uses linear resolution. After working the numbers, Soneira concluded that a genuine “retina display” would need 477 pixels per inch to look perfect from a foot away.

Piling on was PCWorld, which ran its own interview with Soneira. He told them that unless you held the iPhone 4 at least 18 inches away, it couldn’t achieve retina quality. He added further that the iPhone “actually needs a resolution significantly higher than the retina in order to deliver an image that appears perfect to the retina.”

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