You somehow get an idea about how much of a big deal the iPhone 4 is when display experts and retinal neuroscientists start debating on Apple’s claim about the Retina Display’s visual awesomeness. To be specific, Jobs said that the iPhone 4’s display had a higher resolution than what the human retina can detect. Display expert Raymond Soneira then gives the figures shortly after the launch—basically saying that it’s all marketing bullsh*t. Now retinal neuroscientist Bryan Jones steps up to the plate and bats for Apple, saying that he’s cool with what Steve Jobs said and calls “no bullsh*t.” The numbers, eye-facts and microscopic close-ups of Apple’s displays after the break.

First, Soneira’s take on the Retina Display:

Steve Jobs claimed that the iPhone 4 has a resolution higher than the Retina — that’s not right:

- 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 (ppi). At 8 inches it’s 716 ppi. You have to hold it out 18 inches before it falls to 318 ppi.

- So the iPhone [4] 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.

It’s a great display, most likely the best mobile display in production (and I can’t wait to test it) but this is another example of spec exaggeration.

In an interview published on Wired, Soneira also added that the Retina Display was “reasonably close to being a perfect display, but Steve pushed it a little too far.” Soneira said he wanted to highlight that “retina display” is a symptom of a larger problem of market puffery in the display industry. “The marketing puffery is now in control,” Soneira said. “Everything that’s being said now is just this superamplified imaginary nonsense, and the only way to get people’s attention now is making more outlandish statements.”

In a way, we have to agree with his sentiments. Because really, if presentations were done in perfect honesty, we’re guessing there’d be shorter lines on launch day. (We imagine it going like this: “Check out our new [product]; made in a factory in China by thousands of underpaid workers who may or may not have been jumping off dorm building roofs because of monotonous depression, the new [product] comes with a lot of new features like a screen with a comparably better resolution. Also we focused on generally improving everything on the old [product] while maintaining its lack of an SD card slot…”) Yeah, who are we kidding. We’d probably still be lining up in front of said product’s store on opening day anyway.

Anyway, here’s retinal neuroscientist (and self-professed “fan of Apple”) Brian Jones’ take on the Retina Display, and showed microscopic images of Apple’s different iDisplays as a comparison:

While Dr. Soneira was partially correct with respect to the retina, Apple’s Retina Display adequately represents the resolution at which images fall upon our retina.

-Essentially, this is a claim of visual acuity which is the ability of the visual system to resolve fine detail.  There are an awful lot of considerations to take into account when making such a claim such as contrast, distance, the resolution of the display and some metric of pixel size which gives you an estimate of visual resolution on the retina.

-A “normal” human eye is considered to have standard visual acuity or 20/20 vision.  This means that a 20/20 eye can discriminate two lines or two pixels separated by 1 arcminute (1/60 degree).

-If one assumes that the nominal focal length of the eye is approximately 16mm, an optimal distance from the eye for viewing detail might be around 12 inches away from the eye which is reasonable to assume for someone viewing detail on their iPhone.

-Dr. Soneira’s claims are based upon a retinal calculation of .5 arcminutes which to my reading of the literature is too low.  According to a relatively recent, but authoritative study of photoreceptor density in the human retina (Curcio, C.A., K.R. Sloan, R.E. Kalina and A.E. Hendrickson 1990 Human photoreceptor topography. J. Comp. Neurol. 292:497-523.), peak cone density in the human averages 199,000 cones/mm2 with a range of 100,000 to 324,000.  Dr. Curcio et. al. calculated 77 cycles/degree or .78 arcminutes/cycle of *retinal* resolution.  However, this does not take into account the optics of the system which degrade image quality somewhat giving a commonly accepted resolution of 1 arcminute/cycle.  So, if a normal human eye can discriminate two points separated by 1 arcminute/cycle at a distance of a foot, we should be able to discriminate two points 89 micrometers apart which would work out to about 287 pixels per inch.  Since the iPhone 4G display is comfortably higher than that measure at 326 pixels per inch, I’d find Apple’s claims stand up to what the human eye can perceive.

Yeah, talking about eyes with the numbers? It may hurt your head. But what did we all learn? Aside from the fact that the Retina Display—while not perfect—is one of the best on a mobile, nothing much else. Also, listening to eye experts debate? Not so exciting.

Tags: Apple, iPhone, iPhone 4, Mobile Phones, Retina Display

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