Nearly half (46%) of American adults are smartphone owners as of February 2012, an increase of 11 percentage points over the 35% of Americans who owned a smartphone last May. Two in five adults (41%) own a cell phone that is not a smartphone, meaning that smartphone owners are now more prevalent within the overall population than owners of more basic mobile phones.
gadgets
Q: I recently got a Verizon iPhone—it’s my first new phone in about eight years, if you can believe that. What apps do I absolutely need?
A: Welcome to the future, you crazy Luddite! You are officially a mobile digital citizen—you can now check your email on the beach! You will be able to settle bar arguments with the power of the Google! But more importantly, as you grow more intimate with your newfangled device, as it becomes a William Gibson-esque appendage, you will wonder how we pre-iPhone, postindustrial humans didn’t go extinct from the weight of ennui we were forced to bear on a daily basis—lines, commutes, business meetings, bad dates, dinners with the family. The true value of the iPhone isn’t being continuously plugged into the Internet. It’s that it makes the most boring moments in life mildly enthralling.
Simply, a must post due to the “William Gibson-esque” coinage…
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).
The ability of an optical system to resolve fine detail requires minute spacing of optical detectors. In the retina, there detectors are the photoreceptors. Objects we look at at projected through the cornea and lens and imaged on the back of the eye on a plane that ideally lines up with the retinal photoreceptors.
Theoretically the limit of retinal resolution, say the ability to distinguish patterns of alternating black and white lines is approximately 120pixels/degree in an optimal, healthy eye with no optical abnormalities. Again, this corresponds to one minute of arc or 0.000291 radians (π/(60*180)). 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.
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