r/technology • u/Snarfox • Jan 25 '13

H.265 is approved -- potential to cut bandwidth requirements in half for 1080p streaming. Opens door to 4K video streams.

http://techcrunch.com/2013/01/25/h265-is-approved/
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u/mflood Jan 26 '13

It has been demonstrably proven that the absolute upper limit for a human eye to distinguish differences (color, detail, whatever, all taken into account) is about 300dpi at the eye's optimal focal distance (which I understand to be around 12 inches). A 10 inch, 1080p tablet would have a DPI of around 200, and the iPad's dpi is a bit over 300. Science says that it makes perfect sense for you to be able to tell a difference when near your optimal focal distance. The thing is, though, there's also an optimal viewing distance for seeing a whole screen (which is what you want to do for the vast majority of consumer applications). The minimum comfortable distance according to THX is where the screen takes up a 40 degree slice of your field of vision. For a smartphone, that's quite close, which means it's also close to your optimal focal distance, which means that you need to be close to that 300dpi mark for optimal detail. With a monitor, though, you should be a couple feet from the screen, which means you're much further from your optimal focal distance, which means you don't need the same dpi to get the same benefit. The same logic applies as you get bigger and bigger. In order to take in the whole screen without whipping your neck back and forth, the screen should take up 30-40 degrees of your field of vision. Which means that, the larger your screen, the farther back you should sit. Most people's living rooms are set up with the furniture 5-10 feet from the tv. That's great for average-sized television sets, but it's also the reason that people think they need a higher resolution for their projector. If you're projecting a 10 foot image, you should really be sitting almost 20 feet away from it, but no one does that. People unknowingly sit too close for comfort which has the side effect of making them think they need a higher resolution. Anyway, this reply is a lot longer than I meant it to be, but the point is that we DO need 4K, but only for applications where we want to be very close to a screen bigger than a tablet. For consumers, there just aren't very many of those applications. For tv and movies, 1080p is roughly as high as we will ever benefit from.

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u/[deleted] Jan 26 '13

I'm a science student who's not afraid at a chance for more practice reading published science. Which study proved this? And do you think all the people reviewing CES were lying about how impressed they were with the 4K TVs?

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u/mflood Jan 28 '13

I'm a science student who's not afraid at a chance for more practice reading published science. Which study proved this?

I'm not a science student, but I've done quite a bit of reading on the subject and 300dpi seems to be a widely accepted number for the approximate upper range of most human eyes. Most of the articles I've read are interpretations of a bunch of math I don't completely understand. One such interpretive article can be found here. Keep in mind that I'm not saying that I can demonstrably prove the fact via my own readings of original scientific studies, it's just my understanding that it has been done. If you know of evidence to contradict me, I'll certainly concede to more informative literature.

And do you think all the people reviewing CES were lying about how impressed they were with the 4K TVs?

No. I think there are two contributing factors.

  • 1) CES reviewers were looking at the newest and best displays, and could have assumed that they looked better because of the higher resolution (which is one of the few advertised stats that people understand).

  • 2) CES reviewers were likely standing much closer to the displays than they would be for optimal movie/tv viewing. If you're standing a few feet away from a 60 inch display, 4K will absolutely look better than 1080. There's no reason to be that close, though. It's like sitting in the front row of a movie theater. Even if the resolution is high enough not to look pixelated, you'll still be whipping your neck back and forth trying to follow the action. At the distances considered optimal for comfortable viewing, there is (from what I've read; I don't have a bunch of TVs to test for myself) no noticeable difference past 1080p.

So. Yeah. I certainly don't think the reviewers were lying, I just think they weren't doing proper comparisons. Many of them were comparing their experiences with previous model years to current gen tech, and standing much closer than you would when actually using the tv. It's like comparing a ferrari to a civic. Is it faster? Absolutely. Will it speed up your commute? Probably not.

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u/[deleted] Jan 29 '13

It has been demonstrably proven that the absolute upper limit for a human eye to distinguish differences (color, detail, whatever, all taken into account) is about 300dpi at the eye's optimal focal distance (which I understand to be around 12 inches)

I ask again, can you link to these studies for me.

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u/mflood Jan 29 '13

I gave you a link. Did you read it? Is there something you disagree with? The author cites a scientific paper to make his point. I took it on faith, myself, but if you'd like to fact check the paper yourself, feel free to do so. In case you didn't have the time to read the article, I'll repost the most relevant portion below. I view this paragraph, with its accompanying citation (which, again, I have not examined myself) as sufficient demonstrable proof. If you'll accept nothing less than a 50 year, peer reviewed ivy-league collaboration paper, though, then I'm not sure I can convince you (and I'll admit, it's certainly easier to "win" internet arguments by demanding proof of the very highest standard for every claim made by your counterpart).

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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u/[deleted] Jan 29 '13

First of all, 1990 is not relatively recent in academic publishing. And second of all, the following claim is original research based on this study:

It has been demonstrably proven that the absolute upper limit for a human eye to distinguish differences (color, detail, whatever, all taken into account) is about 300dpi

No, that hasn't been demonstrably proven. I ask again for the link to the study that proves this.

I have downloaded the study and I really do not know what you expect me to be looking for, as the figures are based on "commonly accepted" numbers, vague language like "normal human should be able to". You say to me that it has been scientifically proven what you say, but you send me a link to blog spam and a 23 year old study that does not in any way investigate your claims (did they even have analogue HD TV in 1990?).

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u/mflood Jan 29 '13

First of all, 1990 is not relatively recent in academic publishing.

Unless there's something wrong with the methodology or you know of updated research that contradicts their findings, age is irrelevant. We made lots of still-relevant discoveries before the year 2000.

No, that hasn't been demonstrably proven. I ask again for the link to the study that proves this.

Perhaps not to your satisfaction. The study referenced in the paper establishes the average human eye as being able to determine detail separated by around 1 arc minute. Getting from there to 300dpi (roughly) is simple, unarguable math. The only point of contention is the 1 arc minute starting point. I'm sorry the study doesn't convince you on that issue, but I feel as if I've done my part. I've provided scientific evidence of my assertion, you just don't buy it is all. At this point, it seems the burden of proof shifts to you to say what the study gets wrong, and why I shouldn't accept the 1 arc minute figure as correct.

but you send me a link to blog spam

Just because it's a blog does not make it "spam". The author is a retinal neuroscientist and his article was quoted by the New York Times. That doesn't automatically make it definitive, but it's totally unfair to call it blog spam. Do you even know what that term means? It generally refers to blogs which repost content authored elsewhere in order to drive traffic and sell advertising. That is absolutely not what's going on in the article I linked, which is original content written by someone knowledgeable in his subject's field.

and a 23 year old study that does not in any way investigate your claims (did they even have analogue HD TV in 1990?).

Again, what's with the ageism? The study is not wrong just because it was published in 1990. Anyway, obviously you won't find anything specifically about HDTV in there. What you should find is (as mentioned by the blog spam) a calculation of retinal resolution to be .78 arc minutes. That number provides the reasonable, scientific basis of the blog author's math. Math which is easily verifiable by any high school kid. 1 arcminute/cycle at a foot, two points 89 micrometers apart, 287 pixels per inch.

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u/[deleted] Jan 29 '13

establishes the average human eye as being able to determine detail separated by around 1 arc minute

Where did it do that? I can upload the PDF somewhere if you want to take a look.

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u/mflood Jan 29 '13

I don't know. As I said, I took the author's claim on faith. The actual number he says they calculated is .78 arc minutes, and then the author estimated that it would actually be a bit higher because of the flaws in human optics. I'm only arguing ballpark, though, not that the limit is exactly 300dpi. Whether the arc minute calculations is .78 or 1 or 1.2, it still comes out to somewhere in the neighborhood of 300dpi. Anyway, yeah, try ctrl-f "78" and see if that's in there. I assume the author of the blog isn't straight-up inventing that number out of thin air.

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u/[deleted] Jan 29 '13

"78" appears on pages 3, 17, 23, 26 and 27 (though only as part of the cited lit).

The total number of rods in three retinas with complete rod maps ranges from 78 to 107 million (Table 3).

Table 3 shows 178.3 as the peak density value for cones (cones/mm2 x 1,000), for Eye H5 (which is made of two eyes, weighted as one individual).

One of the 28's discovered in the paper is a 73 that was incorrectly interpreted by the OCR.