1080p and the Acuity of Human Vision

[emorphien]

from http://www.carltonbale.com/2006/11/1080p-does-matter/

I haven't done the math to check if the graphic is right, but it seems reasonable.

 

[wallaua]

I am building a media room. I have read as much as I can about proper viewing distance, but I still cannot figure out how to calculate the appropriate viewing distance. I will be viewing a 130"W x 55"H screen for 2.35:1, which results in a 41-degree viewing angle, masked to 98"x55" for 1.78:1 (~31 degree viewing angle) and 73"x55" for 1.33:1 (~23.5 degree viewing angle). My viewing distance is 14 feet. I plan to use a front projector with an anamorphic lens on a sled, with a Realta-driven video processor. The screen width is maxed out, and the viewing distance is fixed. The graph above suggests that I am slightly too close, but in the ball park. Will I see artifacts ? My more critical question is based on the range of sources I will have: Blu-ray playing 1080p & 480p DVDs, DirecTV HD & SD, Time Warner NYC cable HD & SD, FIOS, OTA HD, Media Center, all going through the Realta processor. Isn't the answer that the viewing distance is source-dependent ? Is ambient light a factor, or are you assuming a blacked-out room ?

Re John's article, it begs the question re what is the proper viewing distance for a 50" 1080p plasma.

 

[emorphien]

Re John's article, it begs the question re what is the proper viewing distance for a 50" 1080p plasma.

If the graphic I posted is right, it's about seven feet to take full advantage of 1080p, but you'd start to notice an improvement over 720P as you get closer than 10 feet. (assuming 20/20 vision if I recall)

 

[mike c]

all this talks about how far away you can sit ... what about: how close can I sit?

e.g. can I sit 8 feet away from a 100" screen?

 

[emorphien]

Why not? I think that would probably give me a headache but that graphic will tell you what you'll see.

 

[avaserfi]

all this talks about how far away you can sit ... what about: how close can I sit?

e.g. can I sit 8 feet away from a 100" screen?

I think sitting 8 feet from a 100 inch screen is about right with 1080p closer and youll probably start to see pixels but if your sitting closer youll probably get sick first.

 

[Jedi2016]

Mine falls right into the "benefit of 1080p starts to become noticable". Which sounds about right, because I have noticed differences between 720p and 1080p video (of the same source). While I can't necessarily make out more "detail" on the 1080p picture, it just looks overall sharper. When watched back-to-back, the 720p looks just a little soft by comparison.

That's what I see, anyway.

 

[Einomies]

While discussing the ability of the human eye to see the pixels and at what distances, has anyone actually considered that humans have two eyes, and the visual aquity tests usually have you use only one eye.

We also have a brain that can compare the image from two slightly offset eyes and basically construct an image that is sharper and more detailed than what the individual eye can theoretically see. In fact, the brain will do it with one eye only, by constantly moving the eye around and constructing an image from the "snapshots" it has taken from different spots.

It's like the techinque they use in amateur astronomy. You take one telescope, one standard webcam, 50 photos of the moon and let the computer calculate a high-res combination from the photographs. You can calculate sub-pixel size details, when you compare the differences between the images - as long as they're not all exactly on the same spot, so you get differences between the pixels.

These theoretical figures don't really tell us what we can or cannot see when we set out to actually look at something.

One way of testing your personal viewing distance would be to display a moiré test grid on your LCD. It's a chessboard pattern with alternating black and white pixels.

A proper LCD with proper scaling won't have any problems showing that grid exactly the way it is. Here's the trick: when you look at it and move your head back and forth, you start seeing halo-like objects. These are actually the moire patterns of your own retina. Move your head back until you stop seeing them and the image turns to a dull grey color without any pattern.

That's where your real limit is. Though you might notice that if you look at the screen, you can still see the grid pattern at places. That's your two eyes and brains at work.

 

[Kolia]

Nice post Einomies.

Any idea where such a pattern can be found for testing my display?

 

[Einomies]

Just google "moire focus test for monitor tweaking"

I'm apparently not allowed to post URLs.

 

[agabriel]

I should preface my post with I haven't had a chance to view 1080, my TV runs in 720p mode and for the most part I like it. I also don't run brand new equipment.

So this weekend I upgraded my receiver. I went from a Denon 3801 to a 3803; like I said I don't run new stuff and I wanted upconversion. So I notice two differences one of which is clearer audio and video (this really surprised me). I could never make out all of the audio in the comcast Bengals commercial, I can now. The video also appears clearer and a bit brighter. So, with that said, I think the differences will become more apparent in the next few years. HDMI, despite being a spec for a few years is in my opinion still young and only starting to come in to is own. I think it takes the manufactures and circuit designers a few iterations to really get it right. I think the differences I'm experiencing between the 3801 and the 3803 are perfect examples of this.

So, I think both sides of this topic are correct. I think with the right hardware people will see a difference.

Maybe I'm way off basis, but thats my impression.

Anthony

 

[WndrBr3d]

Anyone want to hop in the way back machine with me to bring back up this article and how it relates to 4k UltraHD?

 

[Pyrrho]

Anyone want to hop in the way back machine with me to bring back up this article and how it relates to 4k UltraHD?

You might want to look at the calculator here and the chart and simplified calculator here. Here is the chart:



One thing to keep in mind is that they are based on having 20/20 vision. If you have worse vision, you can sit closer, and if you have better vision, you will want to be farther away than what is indicated there. But for someone with 20/20 vision, sitting only 8 feet from the screen, one would need a TV larger than 61 inches in order for it to make any difference whether one had 1080p or anything with higher resolution (like 4k). And if one is 10 feet away, one would need a TV larger than 76 inches for 4k to matter instead of having 1080p (again, assuming 20/20 vision).

The upshot is, for most people with the size TV and viewing distance that they have, 4k will be completely irrelevant. But many of them will buy it anyway, because when they are 3 feet away from the screen at the store, they will be able to clearly see the difference between 4k and 1080p, but then they will put it so far away from their viewing position that they will have completely wasted their money on the higher resolution. But people have long wasted money in their choices of AV systems, often spending too much on amplification and too little on the speakers, and thus they have inferior sound to what they could have had for the same or less money. But any fool can tell that 4k has more detail than 1080p, and that 120 watts is more than 100 watts. The thing is, often those are not differences that will matter in actual practice, depending on all of the other circumstances involved. And some of the things that matter are hard to quantify (like better speakers), and so people often don't take enough care with those things that make a real difference.