Resolving The iPhone Resolution
Since the recent announcement of iPhone 4, there have been a lot of discussions and heated debates about the new iPhone’s Retina Display. The new iPhone 4 display has 326 ppi (pixels per inch), which is four times the pixel density of previous iPhone models (163 ppi). In Steve Jobs’ keynote speech, he said:
It turns out there’s a magic number right around 300 pixels per inch, that when you hold something around to 10 to 12 inches away from your eyes, is the limit of the human retina to differentiate the pixels.
Simply put, Apple claims that the human eye cannot distinguish image quality improvements beyond 300ppi. But in Wired Magazine’s interview with a display expert, Raymond Soneira of DisplayMate Industries, he said that the claim was overly exaggerated. In the article, iPhone 4′s ‘Retina’ Display Claims Are False Marketing, Soneira explained that an accurate “retina display” need to have 477ppi at 12 inches.
A nice article was written by Phil Plait of Bad Astronomy which explains the math behind the display resolution. What’s great about the article is that he showed the calculations in deriving the pixel density of each of the claims. He showed that the average human vision can only resolve 286ppi, which tells that the Apple claim is perfectly acceptable.
The full article can be read here.