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4K vs HD TV


Chris_L 7 5.5k United Kingdom
13 Jan 2016 11:52AM
You say about your Retina screens:
Quote:no matter how close I get, I can't see the individual pixels. That means if the pixel density was further increased, I still wouldn't be able to see any additional detail because it's already gone beyond my ocular acuity

That's how I want my TV to be, it isn't so I'll buy a 4k one when the time is right. I've got a camera that does 4k video and I'd like to see the results on a 4k display.

I'm not at all convinced by the argument of viewing distance. If I go as far away as possible from my 1080p tv and toggle between BBC1 HD and BBC1 SD I can instantly see more detail on the HD channel.

If at the other side of the room I can see more detail from a 4k TV than from a 2k TV then I won't be surprised. And if I move in for a closer look and start to see more detail rather than starting to see pixels... bonus Smile
ChrisV 14 2.3k 26 United Kingdom
13 Jan 2016 12:20PM

Quote:
I'm not at all convinced by the argument of viewing distance. If I go as far away as possible from my 1080p tv and toggle between BBC1 HD and BBC1 SD I can instantly see more detail on the HD channel.



Why not? I go back to the example of the billboard. I did a campaign in my local area that went on a few 56 sheets [that's the number of pieces pasted on to the billboard]. I shot images on a 5DII [vertical resolution in portrait @5616 pixels]. The billboard is about 12ft high, but the image would only be around 10ft. Let's say the image used the whole of the camera's area [it was actually a slight crop - half figure in the example I'm thinking of]. 10ft/5616px comes out at a pixel density of 23.4ppi. How on earth do you get away with that? Large format printers these days use stochastic screens [random dot patterns] to disguise the low resolution, but the detail is nevertheless minuscule in absolute terms.

It nevertheless looked sharp from a distance because I'd used studio lights [and the 70-200 f2.8 which is a really sharp lens] so you are perceiving the same detail as you would if the image was reproduced at 150lpi >300ppi on a printed A4 page. The distance makes all the difference. If you went in as close as you would view a magazine page, her hand possibly wouldn't even look like a hand...
keithh 17 25.8k 33 Wallis And Futuna
13 Jan 2016 2:07PM
Isn't the point more like "Can you see a difference between the two screens at a typical viewing distance?"(Jo Blogs Sofa to TV) and the answer is you can. Or I can would be the answer.
lemmy 14 2.9k United Kingdom
13 Jan 2016 3:34PM
The argument that detail perceived is dependent on viewing distance is irrefutable. It's a physical and pretty obvious fact easily demonstrated. As ChrisV says, take a look at a large poster from across the road, full of detail and very sharp. Walk up to 1 foot away and you cannot make out any detail at all. The only reason that one TV can look worse than another is that from a given viewing distance its resolution is less than the human eye's. Once the eye's resolution is reached, no further improvement can be made. What can be stated as fact is that a 4k TV will allow you to sit closer to it than an FHD without perceptible degradation of the image.

Worked out according to the acuity of the normal human eye, pixelation (ie breakdown of perceived image resolution) can be observed on a 1080p TV at 1.5 times the screen diagonal. So, my 26" TV will start to look pixelated at about three feet viewing distance. I actually watch from more than twice that because I don't have a huge room and I hate huge TVs. So 4k for me is completely redundant.

The big problem for 4k TV is hardly ever mentioned in the flurry of techno whizzery. How do you deliver it? Much content is delivered via the net these days and technical requirements for 4k are 15-20mbps of spare capacity. I'm lucky enough to have 152mbps so no problem....except that even Netflix and iPlayer will stutter now and again on mine, not because of my broadband capacity but because the companies' server's don't have the bandwidth to put it out 100% reliably. That with FHD! I know you can get DVDs but that is fading fast - RIP Blockbusters.

Actually, lot of people don't have 15 or 20 mbps and even those who do, if you have a child using up 10mbps on YouTube - now you don't. Interestingly, the TV industry says that for an average home at normal viewing distances, a 65" diagonal TV is recommended to take advantage of 4k.

There's a kind of fetishism about sharpness among (especially amateur) photographers but I don't hear anyone complaining about the definition of cinema movies. Ordinary screens are 50 feet wide and much of the content is FHD. Even using cinema's 4k, the pixel density is incredibly low at 96ppi yet the industry says that 4k shows advantage only for the first few rows of the audience.

Practically everyone has an FHD TV these days and they are reliable and long lasting. Good for the consumer, not for the industry. I wonder why they might be pushing 4k?
ChrisV 14 2.3k 26 United Kingdom
13 Jan 2016 3:57PM

Quote:Isn't the point more like "Can you see a difference between the two screens at a typical viewing distance?"(Jo Blogs Sofa to TV) and the answer is you can. Or I can would be the answer.


What are you looking at Keith? 1080p footage vs 4k, or upscaled footage? As mentioned it could well be what you're seeing is greater dynamic range.

Unless you're talking about HUGE displays its doubtful at distance you are actually discerning any more pixels. Even the manufacturers of large-scale 8k units are conceding that the application would be for 'immersive viewing' - that is where the screen occupied your entire field of view. You'd discern rich detail at the point you look at and as your eyes scanned across the scene. In other words more than you'd get in one go - and at a massive scale. I think one manufacturer somewhere also said it was pointless producing full HD TVs smaller than 32" - and that's conservatively small. I don't think anyone's doing UHD smaller than 40" .

There's a very obvious and rational difference when it comes to computer monitors and tablets - no prizes for guessing - it's the distance you view them at.

The Wiki entry on 8k has the following:

Quote:High-resolution displays such as 8K allows the user to have each pixel be indistinguishable to the human eye from an acceptable distance to the screen. On an 8K screen sized 52 inches (132 cm), this effect would be achieved in a distance of 50.8 cm (20 inches) from the screen, and on a 92 inch (234 cm) screen at 91.44 cm (3 feet) away.


I don't know how the formula is worked out, but you can see those are small distances and huge screens. One thing is certain and can be observed and understood by common sense - the further away you are, the more you can get away with very little detail - we don't need gigapixel cameras to produce billboards.
Chris_L 7 5.5k United Kingdom
13 Jan 2016 9:58PM
Even at large viewing distances I can tell the difference between a poster featuring a brick wall and a real brick wall. At what distance should I be unable to resolve the greater detail of the real thing?
Paul Morgan 20 19.5k 6 England
13 Jan 2016 10:47PM
Its going to be a while before I`m ready for a 4K tv, I`ve only just (since May) bought my first HD tv Smile
ChrisV 14 2.3k 26 United Kingdom
14 Jan 2016 10:32AM

Quote:Even at large viewing distances I can tell the difference between a poster featuring a brick wall and a real brick wall. At what distance should I be unable to resolve the greater detail of the real thing?


Are you sure? Trompe-l'ils have been fooling people for centuries. If you can tell the difference between a poster of a brick wall designed to look like a brick wall in the proper ambient conditions, you're one in a million or more. Kryptonian eyesight notwithstanding of course....
Chris_L 7 5.5k United Kingdom
14 Jan 2016 2:13PM
I'm just talking about posters on the other side of the roundabout versus real walls.

If on BBC-4 HD they show an image of an oil painting in a frame it looks like a tv picture of an oil painting in frame at 2k (1920 x 1080) I've seen a demo of a 4k TV where a picture of an oil painting in a frame looks like a real oil painting.

I can still tell no matter how many internet posts tell me I shouldn't be able to discern the difference between a 4k and 2k tv at normal viewing distances (aren't people's lounges different sizes anyway?) Grin

ChrisV 14 2.3k 26 United Kingdom
14 Jan 2016 3:14PM
Yeah, but it's still all about distance for the resolution, although as we've discussed picture quality is not just about resolution.

The thing about Tromp l'loeil is that it does rely on accurate perspective and matched lighting - which is why they are often placed at the end of viewing windows or through doorways. The good ones do work though even though pigment on canvas is probably not going to be able to match the amount of detail you can get in a photographic reproduction of 'the real thing'. It is a well established scientific principle that there's a law of diminishing returns on resolution and that's just from a mechanical viewpoint.

I've probably banged on for long enough anyway without getting in to the psychology of 'seeing' which is as much black art as science.
StrayCat 17 19.1k 3 Canada
14 Jan 2016 9:05PM
A friend bought a Samsung 65 inch 4K TV. I talked to him night before last. The problems didn't involve resolution, he understood that before he bought the TV??? The colours were way off, and Samsung support gave him an address where he had to order a Blu Ray DVD which contained a program to adjust the colours. Second huge problem; it sounds like a smartphone speaker, seriously. I said don't you have a Bose system? He said yes, but the sound from the TV through that is crap, so he talked to a tech who advise him to get a separate speaker. So now he has this huge, high tech TV, with a dinky speaker that still sounds far worse than his previous 55 inch HD TV. Also, anything less than HD, of which we still have many channels, is almost unwatchable, as are the old movies on DVD, which is their favourites. Sounds like something I should get involved in.Wink It pays to do research, but knowing my friend as well as I do, he would have. I think it's a case of "must have the latest."
StrayCat 17 19.1k 3 Canada
14 Jan 2016 9:10PM
ChrisV, regards smaller UHD TVs; I thought I saw a 27 or 30" one advertised recently. I think it was 30", because I was wondering how it would work as a monitor for viewing my 4K videos. I'll look around, see if I can find it.
ChrisV 14 2.3k 26 United Kingdom
14 Jan 2016 11:58PM

Quote:ChrisV, regards smaller UHD TVs; I thought I saw a 27 or 30" one advertised recently. I think it was 30", because I was wondering how it would work as a monitor for viewing my 4K videos. I'll look around, see if I can find it.


Actually you're right and I have a 22" 1080p screen I bought for a bedroom - the simple fact of the matter is that few of the manufacturers are now making TVs of lower resolution than that. I expect if you sat on top of it you would see a difference (over the 'HD ready 720p' that is). But the fact of the matter is a lot of HD broadcasts are at the lower level anyway, where you do have to be further away for the pixels to entirely merge in your vision.

I think you'd struggle now to find even smaller TVs that are merely 'hd ready' because the technology has largely been superseded. It doesn't look good on the specs - not that it will make a blind bit of difference from 10 foot away...

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