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1080p, Human Vision, and Reality
Posted by
CmdrTaco
on Tue Apr 10, 2007 10:00 AM
from the even-one-eyed-pirates-like-hdtv dept.
from the even-one-eyed-pirates-like-hdtv dept.
An anonymous reader writes "'1080p provides the sharpest, most lifelike picture possible.' '1080p combines high resolution with a high frame rate, so you see more detail from second to second.' This marketing copy is largely accurate. 1080p can be significantly better that 1080i, 720p, 480p or 480i. But, (there's always a "but") there are qualifications. The most obvious qualification: Is this performance improvement manifest under real world viewing conditions? After all, one can purchase 200mph speed-rated tires for a Toyota Prius®. Expectations of a real performance improvement based on such an investment will likely go unfulfilled, however! In the consumer electronics world we have to ask a similar question. I can buy 1080p gear, but will I see the difference? The answer to this question is a bit more ambiguous."
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Article Summary (Score:5, Informative)
I'm sorry, I was told there would be no math (Score:5, Funny)
Re:Mom might have been right.... (Score:5, Interesting)
It isn't that simple. (Score:5, Informative)
According to the linked text, the "average" person can see 2 pixels at about 2 minutes of arc, and has a field of view of 100 degrees. There are 30 sets of 2 minutes of arc in one degree, and one hundred of those in the field of view, so we get: 2 * 30 * 100, or about 6000 pixel acuity overall.
1080p is 1920 horizontally and 1080 vertically at most. So horizontally, where the 100 degree figure is accurate, there is no question that 1080p is about 2/3 less than your ability to see detail, and the answer to the question in the summary is, yes, it is worth it.
Vertically, let's assume (though it isn't true) that only having one eye-width available cuts your vision's arc in half (it doesn't, but roll with me here.) That would mean that instead of 6000 pixel acuity, you're down to 3000. 1080p is 1080 pixels vertically. In this case, you'd again be at 1/3 of your visual acuity, and again, the answer is yes, it is worth it. Coming back to reality, where you vertical field of view is actually greater than 50 degrees, your acuity is higher and it is even more worth it.
Aside from these general numbers that TFA throws around (without making any conclusions), the human eye doesn't have uniform acuity across the field of view. You see more near the center of your cone of vision, and you perceive more there as well. Things out towards the edges are less well perceived. Doubt me? Put a hand up (or have a friend do it) at the edge of your vision - stare straight ahead, with the hand at the extreme edge of what you can see at the side. Try and count the number of fingers for a few tries. You'll likely find you can't (it can be done, but it takes some practice - in martial arts, my school trains with these same exercises for years so that we develop and maintain a bit more ability to figure out what is going on at the edges of our vision.) But the point is, at the edges, you certainly aren't seeing with the same acuity or perception that you are at the center focus of your vision.
So the resolution across the screen isn't really benefiting your perception - the closer to the edge you go, the more degraded your perception is, though the pixel spacing remains constant. However - and I think this is the key - you can look anywhere, that is, place the center of your vision, anywhere on the display, and be rewarded with an image that is well within the ability of your eyes and mind to resolve well.
There are some color-based caveats to this. Your eye sees better in brightness than it does in color. It sees better in some colors better than others (green is considerably better resolved than blue, for instance.) These differences in perception make TGA's blanket statement that your acuity is 2 pixels per two minutes of arc is more than a little bit of hand-waving. Still, the finest detail in the HD signal (and normal video, for that matter) is carried in the brightness information, and that is indeed where your highest acuity is, so technically, we're still kind of talking about the same general ballpark — the color information is less dense, and that corresponds to your lesser acuity in color.
There is a simple and relatively easy to access test that you can do yourself. Go find an LCD computer monitor in the 17 inch or larger range that has a native resolution of 1280x1024. That's pretty standard for a few years back, should be easy to do. Verify that the computer attached to it is running in the same resolution. This is about 1/2 HD across, and 1 HD vertically. Look at it. Any trouble seeing the finest details? Of course not. Now go find a computer monitor that is closer to HD, or exactly HD. You might have to go to a dealer, but you can find them. Again, make sure that the computer is set to use this resolution. Now we're talking about HD. Can you see the finest details? I can - and easily. I suspect you can too, because my visual acuity is nothing special. But do the test, if you doubt that HD offers detail that is useful to your perceptions.
Finally, n
Re:It isn't that simple. (Score:5, Informative)
Hey, that's unfair (Score:5, Funny)
Re:Hey, that's unfair (Score:5, Funny)
Re:It isn't that simple. (Score:5, Interesting)
As you point out, not everybody has the same visual acuity. My vision is corrected to better than 20/20, and even beyond that, to some extent I've been trained in visual acuity first by going to film school and then by working in the TV industry for some years. My job is to look for picture detail.
I have a 42" 1080p LCD monitor, from which I sit about 6 feet away. I can easily distinguish the difference between 720p and 1080i programming (which gets properly deinterlaced by my TV set, so I'm seeing a full 1920x1080 image). Now, some of that is probably the scaling being done by my cable box, but almost surely not all - and anyway, scaling is never taken into account in the opposite argument (ie. nobody stops to consider that "720p" TV sets are almost all 1366x768 or 1024x768 resolution, meaning they have to scale everything).
I think the bottom line is some people see the difference, some don't, and yes, it depends on how close you sit and how big your TV is. It depends on a lot of things. There's no "yes, you can see the difference" or "no, you can't".
One thing I would say is that with prices being what they are these days, I don't see any reason whatsoever not to buy a 1080p set. The price difference between 720p and 1080p in the same line of sets is usually only about 10-20%.
Re:It isn't that simple. (Score:5, Funny)
The first one knows what he is talking about, and the second guy apologizes for being a bit to harsh in a comment? This is Slashdot, folks. That sort of behavior just is NOT tolerated!
Head on over to Technocrat [technocrat.net] every now and then, will you?
Charles
Re:Article Summary (Score:5, Insightful)
1080p content (Score:5, Insightful)
Read the opposite opinion from Secrets (Score:5, Interesting)
I recently saw an article posted by Secrets of Home Theatre, very well known for their DVD benchmark process and articles.
The article is here [hometheaterhifi.com].
They show numerous examples of how the processing involved can indeed lead to a better image on 1080p sets. Mind you it is not just the resolution, but how 480 material being processed and scaled can look better on a 1080p screen than on a 720p (or more likely 768p) screen. It is a very interesting read. Although if you are already conversant in scaling and video processing some of it can be very basic. I count that as a feature though as most non-technical people should be able to read it and come away with the information they are presenting.
Definitely interesting as a counterpoint.
People Are Blind (Score:5, Insightful)
Re:People Are Blind (Score:5, Insightful)
Re:People Are Blind (Score:5, Funny)
Analogy (Score:5, Funny)
But it does mean that the performance of the car won't be limited by the tires...
More info on 720p/WXGA (Score:5, Informative)
At some point, panel prices will stabilize, but most people won't require this either way. And, as I mentioned, very few sources will output 1080p anyway. The ones I know of: Xbox360/PS3, HD-DVD, Blu-Ray and PCs. All broadcast infrastructure is capable of 10-bit 4:2:2 YCbCr color sampled 1920x1080, but even that is overkill and does not go out over broadcast infrastructure (i.e. ATSC broadcasts are max 1080i today). The other thing to distinguish is the frame rate. When most people talk about 1080p, they often are implying 1080p at 60 frames per second. Most Hollywood movies are actually 1080p but at 24fps which can be carried using 1080i bandwidths and using pulldown. And you don't want to change the frame rate of these movies anyway because it's a waste of bandwidth and, if you frame rate convert it using motion compensated techniques, you lose the suspension of reality that low frame rates give you. The TV's deinterlacer needs to know how to deal with pulldown (aka "film mode") but most new DTVs can do this fairly well.
In other words, other than video games and the odd nature documentary that you might have a next-gen optical disc for on a screen size greater than 40" and for the best eyes in that case, 1080p is mostly a waste of time. I'm glad the article pointed this stuff out.
More important things to look for in a display: color bit depth (10-bit or greater) with full 10-bit processing throughout the pipeline, good motion adaptive deinterlacing tuned for both high-motion and low-motion scenes, good scaling with properly-selected coefficients, good color management, MPEG block and mosquito artifact reduction, and good off-axis viewing angle both horizontally and vertically. I'll gladly take a WXGA display with these features over the 1080p crap that's foisted on people without them.
If you're out buying a DTV, get a hold of the Silicon Optix HQV DVD v1.4 or the Faroudja Sage DVDs and force the "salesperson" to play the DVD using component inputs to the DTV. They have material that we constantly used to benchmark quality, and that will help you filter out many of the issues people still have with their new displays.
Content (Score:5, Insightful)
Many TV manufacturers have been pushing 1080p. They have even showed images of sports and TV shows to show off their TV's great picture. However, the fact is that it is very unlikely that anyone will be watching any sports in 1080p in the near future in the US. Television content producers have spent millions upgrading to HD gear that will only support 1080i at the most and 720p as the top progressive scan resolution. They are not likely to change again to go from 1080i -> 1080p to benefit the few folks with TVs and receivers that support 1080p. As others have pointed out, 1080p isn't even supported by the HD broadcast standard.
The only sports you will seen in 1080p will be some crappy sports movie on Blu-ray.
Viewing distance calculator (Score:5, Informative)
It has viewing distances for user selectable monitor/TV/projector resolutions & sizes, seating distances, optimal viewing distances, seating heights(?!), THX viability(?!) etc. It's well researched and cited.
No I'm not affiliated with it, I just found it and liked it.
Perhaps true, but technically iffy (Score:5, Informative)
Of course, we are looking at moving pictures, which have different, more subjective requirements. A lot depends on content and "immersion". Many people watch these horribly small LCDs (portable and aircraft) with often only 240 lines. Judged for picture quality, they're extremely poor. Yet people still watch, so the content must be compelling enjough to overlook the technical flaws. I personally sometimes experience the reverse effect at HiDef -- the details start to distract from the content!
Your target audience... (Score:5, Funny)
If you lean into your honey for a kiss, she doesn't get all pixellated when you get close to her face.
Consider your target audience...
Re:The difference is when you get close (Score:5, Funny)
Dude, this is Slashdot. When a Slashdot reader leans into his honey for a kiss, she *does* get pixellated...
Re:Does anyone even broadcast 1080p.... (Score:5, Interesting)
Then she walked past a smalled 32" LCD that only supported 720p/1080i and she said, "this picture looks so much better, and the TV is $1000 less! Why?"
I casually explained that the expensive TV was tuned to a normal TV broadcast, while the cheaper TV was being tuned to ESPNHD. She looked and realized that the most expensive TV getting a crappy signal isn't going to look all the great.
I still want a nice LCD that supports 1080p, but I'm not pushing for it immediately until I can afford a PS3 and a nice staple of BluRay movies to go along with it.
720p looks IMMENSELY better than 480i, or any crappy upscaled images my fancy DVD player and digital cable box can put out. I have yet to see a nice, natural 1080p image myself, but I'm willing to bet I will be able to tell the difference.
If anyone recalls, there were people who insisted that you couldn't really tell the difference between a progressive and interlaced picture.
Re:Does anyone even broadcast 1080p.... (Score:5, Informative)
Wow, this is wrong. Since you mentioned Verizon, you must live in the USA. NBC and CBS both broadcast in 1080i right now. Discovery HD and Universal HD do too. Those come to mind fairly quickly. I'm sure there are others. By the way, I wouldn't hold my breath about 1080p TV broadcasts. The ATSC definition for high def TV used in the USA doesn't support it at this time because the bandwidth requirements to do this are enormous.
Re:IMAX (Score:5, Funny)