Linked by Thom Holwerda on Sat 11th Aug 2012 14:31 UTC
PDAs, Cellphones, Wireless "I decided to write this post after having too many heated discussions with many users across many blogs. After hearing repeatedly; 'The iPad will have a better display' or 'It sucks because it's not Retina' I figured it was time to break the argument down and dispel the 'Retina' myth." Fantastic post at The Verge.
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Don't underestimate the human vison system
by izomiac on Sun 12th Aug 2012 02:28 UTC
izomiac
Member since:
2006-07-26

I'm fairly amused at how it's taken for a given that the "retina" screen is the best the eye can see. Our photoceptors can detect a single photon. There are ~25,000 cone cells (color) per eye in the fovea, which sees about four square inches at arm's length. So 12,500 cone cells per inch at a couple feet, plus some rods as well.

Obviously, that's not the resolution we see at. Our visual system heavily compresses information in an analog system, then our brain reconstitutes it. Given the overlap, we do a fair bit of superresolution processing while we're at it, so individual photons aren't the lower limit.

Apple's own research points to about 450 pixels-per-inch that a normal person can see at two feet. If you're nearsighted then you can distinguish more. If you're very nearsighted, then a lot more. Does it matter? Probably only with text, where printers and book publishers have long noticed this problem and increased DPI to ridiculous levels (perhaps infinite, as nearby ink dots merge).

And, then there's the issue with color. Many men only can see two types of color (r-g & b), while some women can see four (r, g, g, b). The exact response to light at each wavelength also differs based on genetics. I remember in my high school chemistry class one classmate could see "red" well past 900 nm, while others could barely see it at 700 nm. I think moving beyond RGB color would be cool, but I doubt most people would notice.

Reply Score: 1

unclefester Member since:
2007-01-13

Our visual system heavily compresses information in an analog system, then our brain reconstitutes it. Given the overlap, we do a fair bit of superresolution processing while we're at it, so individual photons aren't the lower limit.


Nope. Our eyes are like low resolution pinhole cameras being waved around randomly.Our visual cortex makes up a picture by creatively interpolating about 99% of the image.

Reply Parent Score: 3

izomiac Member since:
2006-07-26

I'm not sure how you disagree. I was speaking of how ganglia primarily transmits differences between photoceptors down the optic nerve (e.g. only one of three reporting to that ganglion sees light). There's also some motion processing in the retina.

It's more the lateral geniculate nuclei in the thalamus that "interpolates" data from the optic tract and transcodes it for the cortex (IMHO it's more akin to lossy compression, but there's decentralized single processing as well). The cortex is where all signals merge and we get additional postprocessing. I'm not sure if it's the frontal or occipital lobe's cortex that give rise to optical illusions, hysteric blindness, and the various forms of blindsight, which are the more obvious examples of "interpolation" going wrong.

Reply Parent Score: 1

ndrw Member since:
2009-06-30

For the most part we can assume that ~300dpi of full grayscale pixels in a handheld device is more than enough for all except synthetic use cases.

You're right that there are no simple metrics for evaluating our senses. For example, we are unable to detect lack of light for ten milliseconds but anyone would easily see a sudden burst of light, even if it took only one millisecond. Same with the resolution, you could argue that "sufficient" resolution is one when you can't see a single fully-on white pixel on a black background. That could indeed require a higher resolution but frankly speaking who cares, especially that a good solution already exists (just dim the pixel).

Besides, resolution is only one of things to improve (true, it was long neglected). Refresh rates, contrast, and color reproduction are still lagging quite a bit, and there are many tradeoffs involved there too (resolution vs contrast or refresh rate etc.).

Reply Parent Score: 2