Does 4K Resolution Matter?

4k resolution televisions are now widely available and potential buyers are wondering if the extra resolution is worth it. In some cases it is, but in most, it’s not.  The details below can help you decide.

What Exactly is 4K (and 8K) Resolution?

The existing 1080- HDTV standard has a resolution of 1920×1080 (2.1 million) pixels. The UHD resolutions are multiples of the 1080p resolution.

4k resolution is named for the approximately 4,000 (4k) vertical lines of resolution it contains. More specifically, the resolution is 3840×2160 (8.3 million) pixels, which is 4 times that of 1080p. (4k is sometimes called 2160p, and is also known as QFHD – Quad Full High Definition.)

8k resolution has about 8,000 vertical lines and 16 times the resolution of 1080p HD. The resolution is 7680×4320 (33.2 million) pixels. 8k is also called 4360p.

The ITU and the Consumer Electronics Association have officially dubbed both 4k and 8k resolutions as “Ultra High-Definition”, but to complicate things, they are also called Ultra HD, UHD, UHDTV, and even Super Hi-Vision.

HDMI 2.0 is required to fully support the 4k specification. However, the existing HDMI 1.4 spec does actually support 4k resolutions, but is limited to a frame rate of 30 frames per second. The problem is that most components with HDMI 1.4 don’t contain the electronics to support the 4k resolution, even if the connection does.

Will I be Able to Notice the Additional Resolution?

To be able to detect the additional resolution of 4k (or 8k), the screen must be quite large and you must sit fairly close. So how do you know if your particular setup would benefit?  Here’s your answer.

Based on the resolving ability of the human eye, it is possible to estimate when 4k resolution will become apparent. A person with 20/20 vision can resolve 60 pixels per degree, which corresponds to recognizing the letter “E” on the 20/20 line of a Snellen eye chart from 20 feet away. Using the Home Theater Calculator spreadsheet as a base, I created a chart showing, for any given screen size, how close you need to sit to be able to detect some or all of the benefits of a higher resolution screen. (Click the picture below for a larger version.)

Resolution vs. Screen Size vs. Viewing Distance Chart

(Note for those of you not used to reading charts, just jump to the calculator below)

What the chart shows is that, for a 84-inch screen, 4k resolution isn’t fully apparent until you are at least 5.5 feet or closer to the screen. For a “tiny” 55-inch screen, you’ll need to be 3.5 feet or closer. Needless to say, most consumers aren’t going to sit close enough to see any of extra resolution 4k offers, much less 8k.

It’s important to note that research by Bernard Lechner (former VP of RCA Laboratories) found that the average viewing distance of American TV viewers to be 9 feet. This is substantially farther than the 5.5 foot distance required to fully resolve normal-sized 4k screens. I don’t see people rearranging their living rooms to take advantage of the otherwise unnoticeable UHD resolution benefits.

Verification of Calculations by Sony and THX

Sony lists identical required viewing distances in the Frequently Asked Questions section of their product description.  Checkout the Amazon.com product description FAQ for the Sony 65X900A 4k Ultra HDTV. It shows the same distances I have calculated (i.e. 3.6 feet for a 55″ screen and 4.2 feet for a 65″ screen.) If you don’t believe my numbers, confirmation from Sony should help convince you.

Quote from Sony FAQ:
How close to the TV must I sit to appreciate 4K?
The short answer is that between 5 and 6 ft. is the ideal viewing distance for a 55” or 65” Sony 4K Ultra HD TV. However, on a 55“, you can now sit as close as 3.6 ft and enjoy a visibly smoother and more detailed picture (e.g you won’t see the individual pixels). On a 65“ TV, you can sit as close as 4.2 ft. to appreciate 4K.
THX also confirms similar viewing distances:
On a 50-inch 1080p HD display, most consumers can begin to distinguish individual pixels only when standing within six feet of the screen. Therefore if your viewing distance is 10 feet or greater, an Ultra HD 50-inch display will likely have little perceived benefit in terms of image clarity and sharpness [source]

Can you even get 4k and 8k Content?

If you are among the rare few who has a giant screen and sits close enough to it to benefit from 4k resolution, you still need UHD content. Good luck finding it.

As of this writing, the only readily available content source for 4k is the Sony PlayStation 3, and it can only display static pictures (not moving video) using the HDMI 1.4 connection (which only supports a 24 or 30 Hz refresh rate at 4k resolutions.) This may be worthwhile for photographers, but probably not for anyone else. Sony is also offering a UHD movie server that downloads certain Sony Pictures titles in 4k resolution. Due to the limited amount of content, high price, and low adoption rate, this would seem to have only marginal impact on availability of UHD content.

Netflix is offering some material in 4k resolution. I haven’t seen it, so I can’t comment on the quality, but I can say that the bit rate is fairly low for a resolution this high. If 4k is like their 1080p streams, the resolution is OK, but the color banding and color depth are noticeably deficient. Hopefully their 4k streams are of better quality and become more widely available.

In conclusion

The benefits of 4k and 8k are marginal at best. You have to sit unrealistically close to see the full detail and you need 4k source material, which is virtually non-existent. If you use it as a computer monitor to view high resolution source material, you could benefit. Other than that, save your cash and purchase 1080p instead. Or better yet, purchase 1080p OLED TV instead – the near infinite contrast ratio will offer a vastly superior quality image versus 4k resolution on an LED/LCD panel.

ISF states the the most important aspects of picture quality are (in order): 1) contrast ratio, 2) color saturation, 3) color accuracy, 4) resolution. Resolution is 4th on the list, so look at other factors first. Also, be sure to calibrate your display! I recommend the following calibration tools.

Recommended Calibration Tools

“Just tell me what resolution HD TV to get”

If you don’t like reading charts and are looking for a quick answer, enter you screen size below to see how close you’ll need to sit to fully appreciate various screen resolutions.

Enter screen size: inches diagonal

  • For 480p (720×480) resolution, you must sit:
    feet or closer to see all available detail
  • For 720p (1280×720) resolution, you must sit:
    feet or closer to see all available detail
  • For 1080p (1920×1080) resolution, you must sit:
    feet or closer to see all available detail
  • For 4k (3840×2160) resolution, you must sit:
    feet or closer to see all available detail
  • For 8k (7680×4320) resolution, you must sit:
    feet or closer to see all available detail

Note about “or closer” viewing distances calculated above: if you sit closer than the distances shown above, you will be able to see some (but not all) of the detail offered by the next higher resolution.

Written by in: Home Theater | Tags: , , , , , , , , , , , , , , , , | Last updated on: 2015-March-14 |

136 Comments »

    • Paul Anastasios says:

      To Jeff and all Home theatre die hards,
      Lets get one thing straight from the beginning. We can throw around plenty of scientific figures, but at the end of the day I have yet to be shown from any Home Theatre specialist stores a demonstration of 1080p v 4K ? If someone has ever witnessed a 1080p v 4k setup with a 1080p & 4K screens of the same size and make at the high end of the sale spectrum, with the same brand of cables and player to visualise with your own eyes plus playing the same Bluray movie to witness personally, any noticeable difference? I other thing to remember dont get caught up in what the brands feed you through there TV! Also, 8K is still to come out and eliminating any blurring will only be done with OLED. Cheers!

  • Santosh Reddy says:

    Hi carlton, thanx for the chart. Am planning to buy the new 75inch Sony S90, my viewing distance is 9.3 feet away from the tv. Your chart suggested that i sit 10 feet away for watching 1080p content. Does sitting little closer reduce the picture quality ? Please help me… Thank you!

  • Santosh Reddy says:

    Hi carlton, thanx for the chart. Am planning to buy the new 75inch Sony S90, my viewing distance is 9.3 feet away from the tv. Your chart suggested that i sit 10 feet away for watching 1080p content. Does sitting little closer reduce the picture quality ? Please help me… Thank you!

  • :D says:

    “0.59 arc minute PER LINE PAIR. I can find no other research that contradicts this in any way.

    Thus, one needs two pixels per line pair, and that means pixel spacing of 0.3 arc-minute!”

    http://www.clarkvision.com/articles/eye-resolution.html

    Unless I’m mistaken this means that all your calculations are off by about 100 percent.

    • Carlton Bale says:

      As I understand it, 0.6 is what is required to differentiate between 2 line pairs. In other words, the two line pairs look like one line at 0.6 arc minutes, so that is the reference, not 0.3.

      • DarkEnergy says:

        I’m a scientist that have been working with digital images since the late 70’s. I find amazing the propagation of errors in the subject of TV screen size. Resolution is not the same a Sampling. The sampling theorem or Nyquist-Shannon therorem states and proves that to separate two line pairs twice as many sampling elements are needed.

        To verify this, apply the same test you propose to determine the human visual acuity (http://carltonbale.com/visual-acuity-viewing-distance-test-it-for-yourself/) to a TV screen or monitor . You will see that a 1080p screen is unable to resolve 540 horizontal lines. Each pair of lines requires at least 4 pixels to be resolved. The maximum chequered board that can be resolved with a 1080p screen has 480×270 black squares.

        In fact the resolution is worse after taking into account that colour reproduction includes adjacent pixels.

        • DarkEnergy says:

          In other words, it is wrong to assume that the viewer would like to see the individual pixels in the TV screen (Sampling), what it is needed is to match the TV resolution (minimum two pixels) to the viewer’s eye resolution.
          Therefore the viewing distance diagram above is wrong by a factor of two. This means that the optimum distance for matching the resolutions are twice as large.

    • Michael says:

      The article at clarkvision is correct. In order for a display to be limited by human visual acuity pixel spacing must be 0.3 arc minutes apart. That means if you were to print a grid of black-and-white lines spaced 0.6 arc minutes apart (alternating black and white pixels) you’d just be able to perceive them as distinct lines.

      Apple’s marketing people made this mistake when they first started promoting their retina iPhones. They claimed 300pixels per inch at 1.5feet viewing distance was the “retina limit” because normal human vision can resolve 300 line pairs per inch at that distance. However, in order to actually draw 300 pairs of lines in an inch you need to have at least 600 pixels. High quality photo prints are often done at ~600 pixels per inch for this reason.

      Thing is even getting close (i.e. within a factor of two) to that kind of display resolution is pretty much pointless for video playback where your scenes are going to be limited by things like motion blur, and you’ll practically never be portraying scenes with extremely high contrast.

      IMO there’s a far more appreciable difference in picture quality moving from 24 FPS and 48 FPS film (e.g., the latest Hobbit films) than the difference between native 1080p content and 4k content. At 24fps motion blur limits the resolution of most scenes, not the eye, not your display.

      • W Lam says:

        is the world going crazy?. Why is there such hostility and resistance to 4K?

        When 3D TV came out, I read nothing bad about 3D technology, even though in my opinion it was a total waste of money and a sales gimmick.

        I looked at a demonstration of a 4K TV, it looked impressive. When you have a football match, your eye can focus and pick out a face in the crowd. If your eyes zoom into the detail, yes you can see the detail.

        I agree with Michael on his remark about picture quality at 24FPS and 48FPS. I can see motion blur, especially in action shots.

        I am no expert, but digital video be it SD or HD works by compressing video, my eyes keep picking up defects in certain places. There must be ‘bugs’ in those compression algorithms. It irritated me so much so, that I clung onto my old analogue CRT TV for years!

        I have stood in front of many expensive flat screens and said “NO” and walked away without buying.

        • Fred M. says:

          It has nothing to do with hostility or resistance. It has to do with science. It has to do with human optical capabilities. It has to do with expectation bias. It has to do with what you actually see rather than what you believe you see.

          I can take 100 people and show them two identical 1080P televisions and label one 4K. I bet that the majority of people tell me that the 4K television has a better picture. I’ve done listening trials before and watched this happen there.

          You complain about artifacts from compression algorithms for SD and HD and yet you want to embrace 4K, which requires four times the amount of data. You are kidding yourself if you believe that content providers will just launch more satellites and happily quadruple your bandwidth to accommodate 4K. They will employ even more drastic compression with a likelihood of even worse artifacts that are more visible.

          I am someone who loves progress — but I want real progress that can be proven beneficial, not just a way to divert money from products that actually improve the home theater experience (better speakers, better electronics, better acoustical treatments) to ones that just enrich manufacturers.

        • Carlton Bale says:

          I agree that 4k is great – if you sit close enough and if the source isn’t overly compressed. Given the general limits to bandwidth (antenna, cable, satellite, streaming), I see no benefit to 4k content when 1080p content is already over-compressed and full of color banding and artifacts. 4k Blu-ray on a giant screen will be noticeable. Over-compressed 4k streams on a small screen viewed from a far distance is worthless…

          • Paul Anastasios says:

            Hi, The problem I have with 4K or UHD is firstly there is little if any content on disc or Broadcast transmissions and last but not least, if 4K is to be transmitted via cable and stream to homes, they would require cables capable of being able to transmit 100 Terabits or 250 Bluray disc movies data in 1 second. That is not out there at the moment not to mention the Australian Broad Band rollout that is costing us TAX payers BILLIONS does not cater for such high transfer rates. So in my eyes I will never see it not in my life time. So what is the other solution? There is non!

          • Carlton Bale says:

            Paul, The Ultra Blu-ray spec has been published and we’ll start seeing discs and players by the end of 2015. But I don’t think there will be enough movies available to it a worthwhile investment until at least 2017.

            For streaming, the bit rate will be lower than discs, but the h.265 compression is more efficient and will lessen the impact on bandwidth. Still, I think the bandwidth would be much better utilized by focusing on 1080p HDR instead of 4k. Better pixels vs more pixels…and 4k is more pixels than most people need in most situations. So hopefully HDR get’s the attention it deserves. It’s included in the new HDMI spec and I think every TV will include it by year end.

  • reply says:

    Quickly tried your excel calculator, using the calculator to try and get a PPI that is close to the 530 PPI 20×13 inch photo used as an example on that site results in an optimum viewing distance less than half the 20 inches that Clark suggests.

  • reply says:

    Seems way off compared to these numbers as well.

    http://www.swift.ac.uk/about/files/vision.pdf

  • In the past, I fully supported Carlton’s calculations. 4K only matters if you sit ridiculously close to a television — too close to enjoy a theater experience. And I wrote about it in my own Blog: http://awildduck.com/?p=2755

    But, this week, I have jumped horse. With 50″ UHD TVs at just $399, all bets are off. Even if you sit close enough only occasionally, I say “Go for it!” My comment about the cost trade off appears below. But separately…

    Separately, I am beginning to suspect that a demonstration of visual acuity is not the supreme test of resolution enjoyment. Let’s say that the average person cannot discern a pattern tighter than 0.3 arc minutes. But acutance perception often goes far beyond visual perception measured by a subtended angle. Acutance is the subjective perception of sharpness that related to the edge contrast. It is the reason that humans peering through a microscope can distinguish when two hairlines cross paths, even if the width of the converging hairs is considerably.

    Similarly, it is the basis of the printed unit bars on a calipers. The user looks at the millimeter lines of two slightly different scales (one is stretched by a few percent). They read the calipers by finding the opposing lines that create one smooth longer line. The technique results in highly precise and consistent readings, yet the lines are too small to provide accurate read without the acutance trick.

    Just as with edge enhancement in a photo (it makes the image “pop”), I am beginning to believe that 4K may provide tangible benefits beyond the classic observation of a tiny arc angle.
    _______________

    OK Readers. It is just over 1 year since I advised against buying a 4K television. I said:

    I will not spend $1 more to get a TV that goes beyond 1080p
    —and—

    Thundering bass, contrast and black level are [more germane to] an immersive and a more exhilarating entertainment experience.
    Retractions in my Blog are uncommon. I cannot recall the last time that I completely reversed my opinion on an issue, even one that simply reflects personal taste in entertainment gear. But this is one such situation. This week, TigerDirect is selling a 50″ UHD (4K) TV with decent specs for just $399. Since this post will live past the current market, let me point out that this is less than ¼ of the market price last year and about ¼ the cost of a smaller 42″ HDTV just 3 or 4 years ago.

    With the advent of cheap and ubiquitous Netflix dongles from Google, Roku and Amazon, I don’t care about so-called Smart TV features. What I do care about is contrast, motion index, sound and black level. If these things are on par with major brands, then we have only one question to face. Can the eye can discern the tight-grain pixels of 4K TV? As we discus above (and as Carlton Bale has explained in detail, very high resolution is only discernible at a close distance…

    …But this ridiculously low cost skews my past arguments. Even if you rarely sit close enough to enjoy the additional 6.8 million pixels, I say “Go for it!” At this price, all bets are off.

  • Michael says:

    If TVs are designed to take advantage of it, there can advantage to having pixels that are significantly smaller than the resolution limit of the eye.
    The line “full benefit of 4k visible” refers to the distance at which you can resolve individual pixels. However, you need at least 120 pixels/degree to be able to display image content with 60 line/degree features. (Nyquist theorem). This is perfectly analogous to how CD’s have sample rates of 44kHz so that they can playback audio content with frequency content up to 20kHz (hearing limit).
    In practice you still see perceptible benefits with even higher pixel beyond the nyquist limit because real world anti-aliasing algorithms are imperfect and can still result in perceptible degradation of edge contrast even at 120pixels/degree.
    With sub-resolution limited pixels, dithering techniques can also be used to improve the effective dynamic range of a display. For 1080p content on a 4k TV. 4 8-bit pixels ganged into a single superpixel could be used to display amplitude with 10-bits/color.

  • kebos says:

    My 4k 60 inch looks great!Thats all that matters to me and no i dont sit 4 feet from it to see how amazing it looks.

  • Carlos says:

    What’s the source of the graphic of distances related to inches?

  • dav says:

    Screens are getting bigger and bigger and we are not sitting farther away. As 4k screens become larger and more affordable we will notice the difference. 4k is becoming more and more viable as costs go down and media content becomes more available. 4k may indeed be our limit, screens can only be so big before there to big and 1080p did not reach that limit.

    • well, go to a store that has two 50inch screen side by side one at 1080p and one at 4K and sit between them in a normal viewing distance. In my experience there was a photo of a newspaper and in 4k it was well better viewable than 1080p. And I dont mean near the TV I mean in a nice couchy distance the difference was big.

  • the calculator “Just tell me what resolution HD TV to get” is not working! please fix, this seems a great way of extracting a number using your research!

    Thank you!

  • the calculator “Just tell me what resolution HD TV to get” is not working, please fix and thank you for your article!

  • Carlton Bale says:

    The distance calculator form is now working again. Some of the code was deleted by a website update and I was finally able to track it down. Sorry for the inconvenience.

  • Jim K says:

    I have a fairly large family room thus my primary viewing distance will be 12 to 13 feet from the screen. I am considering increasing my current 65 inch to a 75 inch. I am a little confused regarding the advantages of 4K’s additional pixels. Will the additional pixel of 4k be advantages at a 12 to 13 feet viewing distance?

    • Carlton Bale says:

      You probably won’t get much benefit from 4k at that distance. If budget is a factor, definitely go with 1080p. It’s what I would do given the current differential in price.

  • Serious says:

    Seeing as my TV is my computer Monitor I’m in the clear for up to 50inch 4k. Since I sit right in front of it.

  • Elsol says:

    My biggest reason for not bothering with 4k just yet is that there simply isn’t enough media to enjoy it fully. Sure, I could hook it up to my PC for 4k gaming, and perhaps enjoy photos, but as for movies and whatnot… there just isn’t anything worth watching yet. The Blu Ray 4k encode standard has only just been finalized now, so we may start to get something interesting soon, but I think I’ll wait a year or so before jumping on the 4k bandwagon.
    Besides, I find at the distance I sit (7 feet for a 50 inch plasma), contrast and colour balance are far more important to image quality.

    • Carlton Bale says:

      I agree. And you have to upgrade everything to get 4k: source device, receiver, display device. Pretty big investment for marginal return. But eventually it may be cheap enough and common enough to justify.

  • kenji says:

    Hello, I was thinking about oculus rift. What resolution do i need for an oculus rift to give me near real life quality? It’s only about 5 cm from the eye.

    • DancingDirty7 says:

      I heard your vision is 16K, so an oculus that has a lesser FOV I would say 8K?

    • Carlton Bale says:

      With the Oculus Rift, it’s important to note that the screen might physically be 5 cm from the eye, but optically, it’s much farther away. The eye cups within the headset contain 1.5-inch diameter lenses that “zoom out away” from the screen. I can’t find the exact optical specifications, but the lenses effectively make the screen look like it’s farther away. My guess is that if each eye had 1920×1080 worth of resolution, it would be near the resolution needed for best picture qualify. A 4K screen resolution, with each eye receiving half of those pixels, would give roughly double the resolution of a 1080p screen to each eye and look fantastic. I don’t think there would be any benefit to 8k or higher resolution.

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