CurtPalme.com Home Theater Forum

[WanMan]

When is visible resolution desirable? For some time now I've been led to believe that someone with 20/20 vision and sitting a distance equal to 1.5 times the screen's width could resolve 1100 line-pairs as a limit to the human vision. I've kept this in the back of my head whenever I look at flat-panels, because I find that almost everyone I know that has one sits considerable farther away.

With this in mind, I thought it amusing that the mass consumers out there were buying 1080P displays over 768P displays in all size ranges when it was already questionable that those monkey-consumers probably were incapable of seeing 768P let alone 1080P.

For example, I have a 42" flat-panel in my family room, which replaced the old boob-tube. At 42" in diagonal measurement, this translates to 36.6" in screen width. This means that if I had 20/20 vision I would need to be WITHIN 55" distance in order to see 1100 line-pairs. I concluded that since my display was 768P I would could then be 1100/768 times farther away, which is about 79", or about 6.55 feet.

Well, I am more like 12 feet away (144") and I've concluded that I am probably not able to see the entire 768P resolution of this display, and as a result would be a moot point to move up to a same size but higher resolution display. Cool beans. So, I have to wonder, now, the common sense in monkey consumers when I see 56" 4Kx2K displays coming to market.

First question that comes to mind can the human eye see more than 1100 line-pairs at any distance? For instance, let's say I have a display and I am sitting 1.5 times the screen's width away and have 20/20 vision. If I move closer, say 0.75x screen's width) can I resolve more resolution, or am I still peaked at 1100 line-pairs?

I am suspect that the 1100 line-pairs was determined, if only in part, to the condition of the human eye and not some focus condition or distance to display setup. Thus, I have to wonder even when I am following the basis for resolving the most when, and if, this added resolution can come into benefit to me, and not just the reseller.

[Person99]

Here is the chart you seek:
http://s3.carltonbale.com/resolution_chart.html

[CRT_Ben]

I found this article, it includes some pretty involved math:

http://www.tvtechnology.com/features/Tech-Corner/Hoffner_features.shtml

Based on his calculations for a 20/20 viewer, we can obtain a quickie ratio for max viewing distance to fully resolve 1080p: 3,535.7/2037 = 1.73*screenwidth. This is slightly more than the chart that Dave posted, which seems to advocate about 1.6*screenwidth for 1080p. For 720p we have 2.59*screenwidth and 2.25*screenwidth, respectively.

I'd say that the tech article numbers are probably good for those who have exceptional vision and the chart Dave posted is probably better for the average Joe.

[ecrabb]

I'll stay out of the math because it makes my head hurt, but you're absolutely right, WanMan. There is a direct relationship between subject distance and how much resolution your eye can resolve.

The page that Dave linked to really nails it. 1/60 of a degree of arc is what I've read in psychology/biology white papers (not related specifically to home video) on human visual acuity. Based on that you can figure out exactly how much resolution you can (or can't) detect at a given distance - which is exactly what he did. That chart is great. There was a guy on AVS that I was trying to help bat around the the numbers and distance relationships a year or two ago - I wonder if it's the same guy.

The bottom line is that contrary to popular belief, if you sit too far from your TV, 1080p isn't going to look a damn bit better than 720p. In fact, I just read an article recently where some flat panel reviewers threw a 768p plasma into group of 1080p LCD's to see if anybody noticed. Guess which one was picked more often as the display with the "better" picture? Yep, the plasma. Why? It was all about the contrast. It doesn't matter how much resolution you have, if the contrast isn't high enough, our eyes can't resolve it. The phrase 'contrast is king' got thrown out in the article.

SC

[deronmoped]

Well

You have to remember how these sets are sold. The viewing distance at the TV store is only a few feet and on top of that, salesman just sold the guy a 8,000 mega pixel camera, you think the salesman is going to let him walk out of the store with a 768 TV when he can sell him a 1080 display?

Deron.

[ThomasW]

Interesting thread, confirms what I suspected. Remember this is all assuming a 20/20 vision. Many of us, including me, don't have that. Many would probably need to sit closer to their HDTV plasmas, LCD TV's or screens.

[pfloydphanatic]

sh*t man i'm only using 480p of the possible 1080i capability of my ECP 4100 and i can't see the lines.. either my eyes are really bad or the HD6 lenses i have are too soft to show the lines?

[Person99]

[pfloydphanatic]

ThomasW.. what is that in your hand in your user picture or avatar, whatever its called. is that a pocket size crt projector? lol

[mike calcott]

I totally agree. I work part time in an electronics warehouse where we have at least 50 panels of all types LCD, Plasma, SD,HD, and 1080p. In the Sony section we have all models dispaying the same looping demo being supplied from a high definition generator, all being fed a 1080p signal, customers cannot tell the difference, as the image seems the same on all panels. Obviously if a nerdy customer comes in requesting a X series or BR series Bravia I am going to sell him what he asks for, but when you try and advise customers that broadcast signal is 720p or 1080i in Australia and buying a higher grade panel is not going to benifit them, they claim that because the specs are higher on the upmarket models they must be better. Its quite amusing because until you point out which are the higher spec panels they do know the difference. I must admit Sony demo's are the best in the industry and are designed to show their panels at their best.

[pfloydphanatic]

well an ecp 4100 for $150 not bad.

[CRT_Ben]

[Zebu Fellenz]

Feed it 240p, that will give you in your face scanlines for sure

[Fujifrontier]

[pfloydphanatic]

lol thats funny... it makes a really faint image as is. i tried it when i had my colorview rca camcorder

[ecrabb]

Yeah, and then you could get three of the black and white viewfinders, put colored gels over them, feed them separate R, G, and B channels and project a 13" image that would be about 1/10 the brightness of a 13" TV.

It would look like something like this (apologies to ThomasW):

SC

[pfloydphanatic]

please tell me somebody didn't do that.. or somebody has way too much time on their hands i have way too much time on my hands but i would not have a clue how to do that lol

[AnalogRocks]

I've turned my B&W viewfinder on my Sony EDC-55 EDBeta camera into a wee 6" projection to show people what I just shot. I used a pocket fresnel lens and a white wall. The eyecup swings aside and I just held the lens infront of the viewfinder.

That was lighter than toting around the 5" CRT TV.

[AnalogRocks]

I've turned my B&W viewfinder on my Sony EDC-55 EDBeta camera into a wee 6" projection to show people what I just shot. I used a pocket fresnel lens and a white wall. The eyecup swings aside and I just held the lens infront of the viewfinder.

That was lighter than toting around the 5" CRT TV.

[pfloydphanatic]

oh i forgot about those pro camcorders with the really bright viewfinders... yeah that does make sense.

[Dave Lister]

I thinks it's just some indicator lights from some control panel.

But a mini CRT projector would be cool even if a poor performer.