Bryan Jones is a retinal neuroscientist, took a microscope and photographed sub-pixel level images of the iPad, the original iPhone, the iPhone 3G and the iPhone 4G. What he discovered was a non-square-shaped pixel structure of the iPhone 4G’s Retina Display. The pixel dimension was measured to be about 102×78Âµm. Bear in mind Jones noted that he was experiencing difficulty calibrating the microscope and that the measurements are approximates. He also seems to have pictured the iPhones in landscape mode while the iPad was in portrait orientation. Usually the sub-pixel arrangements are red, green, blue going side ways.
Both the original iPhone and the iPhone 3G had a pixel dimension of approximately 500×190Âµm (when iPhone is in portrait orientation). Both photographs exhibited slight blurriness due to the non-bonded nature of the display in addition to the touch layer adding to light refraction. The iPhone 4 pixel-level photograph exhibited no such blurriness thanks to the optical lamination process that almost eliminates light refraction.Â But then I got confused.
Jones mentioned the original iPhone and the iPhone 3G has a pixel dimension of 190×500Âµm. But a paragraph down he lists 176×223Âµm. I thought it was the sub-pixel dimension but that can’t be; it isn’t a multiple of three. What is this? I’m not sure. So I decided to forgetÂ the 500×190Âµm or 190×500Âµm dimension Jones mentioned.
I’m going with 223×176Âµm for the previous iPhones and 102×78Âµm for the iPhone 4. As you can see these measurements are approximate since the larger pixel from the previous generation iPhones is not exactly four times as large as the iPhone 4: the short side is but the long side isn’t.
Another interesting thing is that two Ph.D candidates from Penn State University took some measurements with a microscope and found the pixel dimension of the iPhone 4’s Retina Display to be 20×20Âµm (read iPhone 4 Pixels Under The Microscope for more info). That is a significant difference between the two. Go figure.
The bottom line:
Here is the deal though… While Dr. Soneira was partially correct with respect to the retina, Apple’s Retina Display adequately represents the resolution at which images fall upon the retina.
So when Jobs said, â€œIt turns out that thereâ€™s a magic number right around 300 pixels per inch that when you hold some thing around 10 or 12 inches away from your eyes is the limit of the human retina to differÂentiate the pixels,â€ he was generally right. He was addressing ordinary folks and for most of us his statement about 300PPI as a limit of visual acuity was not exaggerated.