Quote:
Originally Posted by
MFago 
What is the angular resolution of the human eye, and what linear distance does this angle correspond to at 12" away? I believe Steve was claiming that it is 300 dpi.
I don't have the time to do a conversion, and it is also distance dependent, but we are capable of perceiving a difference in two lines as small as 8 arcminutes of angle. This is typically measured with the Snellen methodology which is usually at 12, 16, or 20 feet. This size (8 arcmin.) is about 40% the size of a cone receptor at 16 ft.
Quote:
Originally Posted by
masternav 
yeah - get the receptor thingy BUT how does the visual center process all that data? We are talking perceptivity here not receptivity, processing not physical capacity. Again, don't get distracted by the label - consider the function - unless you are in fact a hopeless pedant. Go back to what the actuall Apple website says about the display and actually watch what Steve Jobs says about it - not the translated, transformed, transliterated abomination that passes for the article here.

The vast majority of what the brain processes is done so unconsciously. We don't have to wake up in the morning and say to ourselves, "I'm going to be extra vigilant today and pay more attention to what my brain is doing". The brain processes everything it takes in. Awareness is another thing entirely. You are making the mistake that many first time Perception students make which is assuming we're aware of everything being processed by the brain. We are not, in fact, we are only aware of less than about 1% of all perceptual activity performed by the brain.
Quote:
Originally Posted by
melgross 
You certainly didn't understand what Jobs was saying. nd what you are saying isn't entirely correct.
Actually I do, and much of what you say here demonstrates that you really don't understand anything about the optics of the eye or the physical relationship between locations in the visual field and how we perceive those objects.
Quote:
Originally Posted by
melgross 
I've been in the photo industry since 1969, and have degrees in biology, as I assume you do, and 300 dpi, ppi, spi, etc., are standards for good reasons. Our visual acuity is limited. Under VERY special circumstances we can see lines, and dots that are finer than we can normally see. But that's under circumstances that are unusual. Under conditions of extreme contrast, we can see details we otherwise can't see. Those conditions don't normally exist for us when reading newspapers, magazines, and books. You might remember that he mentions, specifically, printed matter as the standard there.
My claim about the degree of human visual acuity is based on the standardized Snellen procedure used by every optometrist in the world. Such acuity is usually measured at distances of 12, 16, or 20 feet.
Yes, there are things that can be finer than the resolution of our visual acuity. But we can see things that are extremely small. As I replied to other posters above, details less than one half the size of a cone photoreceptor.
Quote:
Originally Posted by
melgross 
The lower the contrast, the lower our ability to discriminate detail. This is pretty well known and understood.
See above.
Quote:
Originally Posted by
melgross 
You are also making a major error in talking about the density of the retina. The retina is small. There's no point in saying that there are millions of rods and cones per inch. Do you know the size of the retina?
In addition to that small retina size is the fact that the iPhone screen is vastly larger than that retina. Can you figure out how many retinas would be needed to cover the iPhone screen? The point is that the retina has just so many sensing cells, and the iPhone screen has just so many pixels. Talking about the number of cells per inch is a useless statement because that small "sensor" is looking at a much larger screen.
In addition to that is the other fact that we aren't using more than a small part of out retina to image the iPhone screen, so we are just using a fraction of the cells in it. And, in addition to that, is the other fact that while the screen has the same sensitivity from edge to edge, our eye has very poor vision outside a fairly small area in the middle.
The situation isn't as clear as you make it out to be.
I can continue with this, but enough is enough.
No, I'm not making a mistake. Just look it up. The area of the retina has nothing with resolving power. By your argument, eagles, with retinae smaller than ours, should have poorer vision than ours. It is well documented that the visual acuity of birds of prey is superior to humans. What you're saying here is that simply having a bigger retina increases acuity. That is simply false.
The only thing you say here that is even close to correct is that we have better acuity at the fovea than anywhere else in our field of vision. That is true, and my statements above are assuming foveal vision.
Other than that you do not know what you're talking about here.
Quote:
Originally Posted by
cgc0202 
Are you sure you are actually familiar with the biology of vision itself?
And, for that matter the psycology -- what people see, and how they perceive what they saw?
Please do enlighten us with your expertise. Your initial lecture does not suggest you do.
Equating precision with the size of a reinal cell? But then again, if it cannot display anything, how can it be the arbiter of precision, and more important, perception?
I heard, a team of scientists (one of them a professor at Harvard) won the Nobel prize for their seminal work on the biology of vision. You may want to brush up on their work and those who followed on their research. There is also a great body of work on the psychology of vision.
CGC
Yes, I am familiar with that work, I earned a PhD in Perceptual Psychology with an emphasis on visual attention, psychophysics, and physiological psychology at UC Santa Cruz. I now teach Perception at another UC campus now.
Sorry if not listing references here doesn't meet with your approval; I have a lot of other things to do in a day. I forgot the natural way people tend to respond on the internet when you say something simple such as "I have an advanced degree in ..."
I'm not going to waste my time here with these insults or even more politely worded posts as yours. In an earlier response I referenced an excellent Brittanica article that backs up my claims. I would also recommend as starters, "Sensation and Perception" 5th. ed. by Harvey Richard Schiffman, "Vision Science, photons to phenomenology" by Stephen Palmer, and "Foundations of Vision" by Brian A. Wandell, and "Visual Perception, a clinical orientation" by Steven H. Schwartz. Any of these works, especially the first two, will be helpful. The latter two are much more technical, and assume a background in psychology, neurophysiology, and also require first year calculus to understand the mathematics of the computer modeling discussed.
I point other posters to these references, and the ones made in my previous reply here.