While there is little dispute that the new iPhone contains an impressive display, there is debate over whether or not the display actually exceeds the visual capabilities of the human eye. Raymond Soneira, president of DisplayMate Technologies Corps, has done the math and considers the claim to be an example of spec exaggeration.
"The resolution of the retina is in angular measure - it's 50 Cycles Per Degree. A cycle is a line pair, which is two pixels, so the angular resolution of the eye is 0.6 arc minutes per pixel. So, if you hold an iPhone at the typical 12 inches from your eyes that works out to 477 pixels per inch. At 8 inches it's 716 ppi. You have to hold it out 18 inches before it falls to 318 ppi. So the iPhone has significantly lower resolution than the retina. It actually needs a resolution significantly higher than the retina in order to deliver an image that appears perfect to the retina."
By Raymond's math, the exact number of pixels that is visually capable of the human eye at 12", is 477 per inch. Raymond has a PhD in theoretical physics from Princeton and has been studying displays for 20 years, so when he speaks, journalists take note. Wired.com was quick to label Job's claims as false marketing.
Well, at least one other expert has also done the math. Discover Magazine's Phil Plait has run the numbers and seems to side with Jobs. Phil's claim to fame was calibrating a camera on the Hubble space telescope. The explanation is pretty long and technical, but here is the gist of it:
"The iPhone4 has a resolution of 326 ppi (pixels per inch). Soleira says the eye can resolve 1 / 0.0021 = 477 ppi. However, normal vision can see at 1 / 0.0035 = 286 ppi. So the density of pixels in the iPhone 4 is safely higher than can be resolved by the normal eye, but lower than what can be resolved by someone with perfect vision. So what does all this mean? Let me make this clear: if you have perfect eyesight, then at one foot away the iPhone 4’s pixels are resolved. The picture will look pixellated. If you have average eyesight, the picture will look just fine."
Essentially, if you are in the minority of the population that has been blessed with perfect 20/20 vision, then you may notice some pixelation in the iPhone's display. However, if you are of average vision or lower, the Retinal Display will look as smooth as can be (to someone of inferior vision).
The debate over the actual capabilities of the iPhone 4's display is similar to the 1080i vs. 1080p HDTV debate. The fact of the matter is, only those gifted with the finest of eyesights can detect a difference. It is a matter of semantics not worth losing any sleep over. And really, if Apple tells you that you shouldn't have perfect vision, who are you to argue?
