this is the first time i've heard of Soniera.. so I can't speak to his qualifications, but I know badastronomer is a really smart dude.
and by the way.. this really is waaaaay to much math to be doing to determine whether or not the screen looks good. I don't care what it says on paper.. does it look better than the one I have now? yes or no is all i need to know. I don't necessarily care how or whyhttp://blogs.discovermagazine.com/ba...ne-resolution/
So what does all this mean for the iPhone? First, here are the claims.
Jobs claims the iPhone held at 12 inches from your face has pixels too small to be resolved by your eye. Soneira, the display expert quoted in the magazine articles, disputes that. He uses the 0.6 arcmin resolution for the human eye (so we use the scale factor = 5730). Let’s use that and run the numbers.
Something 12 inches away means your eye can resolve dots that are bigger than
12 inches / 5730 = 0.0021 inches
So if the pixels on the iPhone are smaller than 0.0021 inches in size, then Jobs is right. Your eye won’t resolve them. If the pixels are bigger, Soneira is right, and your eye can resolve them.
The actual iPhone 4 has 326 pixels per inch (the display is 960 pixels high, and about 2.9 inches in length). You have to flip that to get the size of the pixel in inches:
1 / 326 = 0.0031 inches
Uh oh! Things look bad for Jobs. The iPhone pixels are too big! At one foot away, your eye can resolve the pixels, and Jobs must be lying!
Or is he? Remember, Soneira used the 0.6 arcmin resolution of the eye, but that’s for perfect eyesight. Most people don’t have perfect eyesight. I sure don’t. A better number for a typical person is more like 1 arcmin resolution, not 0.6. In fact, Wikipedia lists 20/20 vision as being 1 arcmin, so there you go.
If I use 1 arcminute instead, the scale factor is smaller, about 3438. So let’s convert that to inches to see how small a pixel the human eye can resolve at a distance of one foot:
12 inches / 3438 = 0.0035 inches
Aha! This means that to a more average eye, pixels smaller than this are unresolved. Since the iPhone’s pixels are 0.0031 inches on a side, it works! Jobs is actually correct.
[Note: in the articles about all this, they used units of pixels per inch, whereas I've used the size of the pixels themselves. You can flip all these numbers to convert. 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.]