back to article How to choose the right screen size

How big is big enough? It’s a question many of us have asked, as we cruise the aisles of Currys or John Lewis, looking for a new TV. It’s all too easy to be seduced by a special offer, or by extra features like net connectivity, and end up with a TV that’s larger than you anticipated. And while you might make space for a jumbo …

COMMENTS

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  1. Anonymous Coward
    Pint

    Indeed...

    "Hands up who’s rearranged their living room to move all the chairs closer to the screen after buying an HD set? Anyone?"

    Strangely with the screen thinner, we actually moved everything further away to make the living room yield more floor space.

    On a point of resolution, I have a pretty bog-standard 42" Philips LCD and I have found that a UK comedy prog played from an AppleTV2 still looks pretty good even a very low res of only 448x262. BBC documentaries taken from DVDs are encoded at only 624x352, this appears to be right on the limit of almost "blocking" in very dark areas but is perfectly acceptable to watch. After a while you forget all about any minor niggles and simply watch the content rather than the medium. The upshot is that you can store absolute bucket loads of movie files from DVDs on only a small 4TB NAS unit. No doubt in 4-5 years time that res will be useless, but the TV is only 18 months old and has a replacement warranty for the next 4 years so it's not going anywhere for a while yet.

    1. Annihilator Silver badge

      "Blocking"

      "BBC documentaries taken from DVDs are encoded at only 624x352, this appears to be right on the limit of almost "blocking" in very dark areas but is perfectly acceptable to watch."

      That's less to do with resolution, and more to do with compression artefacts. Have a look at your quantiser settings...

  2. Sorry that handle is already taken. Silver badge

    1440x1080?

    There are flat panel TVs out there with non-square pixels?

    Either way it would be very difficult to tell the difference between that and 1920x1080 under most circumstances.

    1. Anonymous Coward
      Boffin

      Scaled

      I think the BBC is talking about broadcast resolution. Every digital TV has a scaler that can scale from a large number of resolutions up to the 1920x1080 panel resolution. (Or to whatever your panel resolution is, if you've got an older HD telly then the panel is likely lower res).

      Even in the SD case, it's common to broadcast TV channels at two-thirds horizontal resolution and get the Freeview STB to upscale them to normal SD. This is typically used on news channels and the like, to save bandwidth. Premium channels like BBC1 and BBC2 get broadcast at full resolution.

      As with all things in life, there's a tradeoff. This one is a trade between picture quality, number of channels, and amount of radio spectrum used.

  3. toof4st

    Or get a tape measure

    For a 16:9 screen with a diagonal picture of size D, you can calculate H using Pythagoras.

    Or use a tape measure

  4. James Hughes 1

    You've got it all wrong....

    There are two criteria for choosing a TV size....depending on where you live.

    1) It must be bigger than the people who live in the council house next door.

    2) It must cost slightly more than what you can afford.

    Simples.

    Now, being serious (did you realise I wasn't being serious above?), were the tests done with very high bitrate images (I may have missed that in the article)? the main problem I have is the crappy blockiness caused by low bitrate FV channels, although it does seem to have improved since the switchover, but that might be wishful thinking. Unless all the videos were pushed passed the point of blockiness these test would be, like a blunt pencil, pointless.

    1. Captain TickTock
      Coat

      It must be bigger than the people who live in the council house next door.

      All of them? What if they're basketballers?

    2. Nigel Whitfield.

      All in the white paper

      The BBC white paper we linked to goes into considerable detail about the methodology.

      The main purpose was to determine the level at which the eye can perceive detail, so static images were used, with an un-manipulated one, and one to which various filters had been applied, noting the point at which the test subjects were able to discern the effect of the filters.

      The result was, as we say, broadly in line with the accepted acuity, 1 minute of arc, which is the figure I used in working out the rest of the maths.

    3. Anonymous Coward
      Anonymous Coward

      low bitrate

      on freesat there's this ``landscape channel'', which shows (er) landscapes etc for use as a sort of relaxing background or something. You wouldn't want to actually watch it, tho, as even even on my tiny 15in crt tele, I can see blocks and other artifacts.

      And when watching some footy the other week, the HD channel version looked detectably crisper than the ordinary one (my freesat box is over specced for my tv).

      1. Anonymous Coward
        Thumb Down

        You made that TV yourself I assume.

        As if you have a CRT TV of any size it will not have the required inputs for HD, just the basic arial or scart connections (and maybe composite).

        But none of those connectors will privide HD content to a TV, just standard PAL resolution.

        To get HD you have to have a TV/Monitor that can handle the digital connectors.

        (Note: the above is for TV's, not PC monitors as they can go higher)

        1. K.o.R

          letters and/or digits

          Not *strictly* true, there were a few CRTs made which did have HDMI inputs. What happened to the signal once inside the box was anyone's guess however.

        2. Anonymous Coward
          Anonymous Coward

          HD channel -> crt

          I didn't think it was a pixel issue, just a bitrate one. After all, footy on tv does involve quite a lot of fast moving tiny figures on the screen.

          What I am saying is that the pic spat out onto the scart lead to my tv looked slightly better if the box was using the HD channel than the standard one.

  5. simon casey 1

    21:9?

    So what about 21:9 screens with proper 2.35:1 aspect input akin to all the photos in the article?

    1. Nigel Whitfield.

      Do your own maths!

      I'll post the workings for all of this on my blog later, so you can see how we calculated the figures. It's fairly easy from that starting point to work out the values for a different screen ratio.

  6. Si 1

    Seeing the extra detail

    I can usually see the extra detail when I switch between the SD and HD versions of a channel, but really, aside from on-screen text or headlines I tend to find I stop noticing the extra detail after a while. I think we're about 2.7-ish metres away from a 42" screen (why do we measure screen distance in metric and screen size in Imperial anyway??)

    At the end of the day, it's program quality not picture quality that counts. You could broadcast Eastenders in 4k and Doctor Who in 480i and I'd still only watch Doctor Who...

  7. Zog The Undeniable

    Obvious stuff

    I could have told the researchers that HD on a 32" set was pointless, since to my (reasonably good) eyes this looks no better than normal PAL on a 28" set. Of course, Americans have been putting up with lower-resolution NTSC on mahoosive TVs for years, so there is more of an upgrade imperative there.

    HD is only necessary due to the relentless increase in screen size. When you get to 40" and above PAL really doesn't cut it, and 40" is a smallish TV by new standards.

    Anyway, we still have a 28" CRT in our living room. The quality of programming is sufficiently bad that we don't feel the need to upgrade. You can't polish a dog's egg.

    1. AndrueC Silver badge
      Thumb Down

      It's not just about the resolution

      >I could have told the researchers that HD on a 32" set was pointless,

      Not necessarily. It's also about the colour range. HD colours are more vibrant and have better degredation. Shiny surfaces actually look shiny rather than just 'a bit more bright'.

      1. Sorry that handle is already taken. Silver badge

        HD Colours?

        What makes HD colours better than SD colours?

        1. Anonymous Coward
          Anonymous Coward

          Better colours

          Combination of canny marketing and the oxygen-free-copper interconnect effect.

        2. Trollslayer Silver badge

          A good question

          Good question with two answers:

          First is colour - the more advanced video encoding (AVC) used for HD supports a wider range of colours than the older system (MPEG-2).

          Second - scene changes. With MPEG-2 SD transmissions there are a certain number of blocks per frame which show up on fast scene changes and are more obvious on HD displays because there is less blurring. AVC supports more blocks per frame and smaller ones with finer movement.

          I bought a decent plasma and had to swtifch from Virgin to Sky because Virgin's HD was in MPEG-2. It didn't help that I work with this stuff so I noticed every block in the end.

          1. Anonymous Coward
            Thumb Up

            re:A good question

            I always thought Virgin HD looked a bit rubbish. Now I have a reason why. Thanks.

        3. Christopher Key.
          Boffin

          709 vs 601

          The RGB primaries used for HD material are more intensely saturated than those used for SD material, hence HD can encode more intensely saturated colours. A lot of screens also support xvYCC, which allows encoding more intense colours still by allowing negative RGB coefficients. So far as I'm aware, no broadcast standards nor mass distribution standards support xvYCC, but if you've a PC displaying photos that use scRGB or similar, that might legitimately be able to exploit it.

        4. Sorry that handle is already taken. Silver badge

          Re: HD Colours

          Thanks for the explanations. I hadn't figured on the fact more advanced codecs were being used for HD broadcasts. Here in Australia I believe we're still on MPEG-2.

      2. Chris Miller

        Colour range

        Perhaps AndrueC is posting from Canada (correct spelling of colour rules out a septic). North America paid the price for being the first to have colour TV by being forced to use the dreadful NTSC (Never Twice the Same Color) standard. US viewers go wild for HDTV as they discover their favourite newscaster doesn't actually have green skin.

        1. DZ-Jay

          Re: Colour range

          The newscaster never had green skin, silly. It was deep, bright pink. His hair was green.

          -dZ.

      3. AndrueC Silver badge
        Thumb Down

        Contentious

        Hmm - seems to be quite contentious this one. Looking around on the web it's also contentious there. I'm no techie so I don't know how/why but the colour in HD pictures just looks so much better to my eyes.

        I used to watch American Choppers before it became really crap and the first time I saw it in HD as astonishing. The completed bikes suddenly became polished and buffed. I've since seen the effect on many things. Grass is another example. On Time Team crop marks are more obvious. Come to that shades in soil are more obvious. I've no idea whether it's the cameras, post processing or the transmission but to my eyes colour is better when watching an HD program.

        Still - if it's not part of the standard then it's possible that my TV (Samsung) and my mate's TV (Panasonic) are just doing something clever for HD. I don't know about my mate's but I turned all that crap off on my Samsung. I'm a strict member of the 'give it to me straight' brigade when it comes to TVs and I've never bought one yet that didn't need a good hour spending turning off features and toning down the colours.

    2. Fisher39

      Technically you can

      Adam and Jamie proved that you could polish that particular item on an eisode of mythbusters

  8. A J Stiles
    Flame

    One thing that would make it easier

    would be to force manufacturers to quote the screen measurement in proper measuring units, i.e. millimetres or centimetres. You know, just like they do in pretty much every other country in the world.

    1. Anonymous Coward
      Anonymous Coward

      Well, you know what you can do

      If you love silly foreign measurements ("we have 10 fingers so we should base everything on 10 and then have lots of fractions, because people find counting harder than dealing with fractions, duh") so much, you could just go and live elsewhere.

      1. Andy Fletcher

        Wow

        You want people who support decimalisation to pack up & leave? TBH I couldn't give a fig what standard of measurement we use here. I just wish we could make our damn minds up and make a bloody decision.

        32", so I'm one of those underendowed watchers. But if I'm playing COD, my nose will be right up to it. If, on the other hand, the wife is watching Desperate Housewives my viewing distance becomes exponentially and progressively larger as the tedium unfolds.

      2. Guy Smillie
        WTF?

        To Robert and other Metric inch-lovers

        I think we should ban people who hate decimals from using them to express their ancient measurements. 7.625 inches? Nope, banned. You must stand by your principals and use 7⅝ inches. I hope for your sake you're not a software developer. Or maybe you could just bring yourself forward to the 19th century and go with 19.3675cm.

        The point abut foreign measurements is also irrational. Unless you're Roman or French then you have no rational choice but to use a foreign system.

        1. A J Stiles

          And strictly speaking

          Given the amount of help the French needed to get it to work, SI (don't call it the metric system, that's a pejorative term) is technically a British invention. We did a sort of cross-licencing deal with France: they let us think we invented front-wheel-drive cars, in return for us letting them think they invented metres, litres and kilos.

          1. Toastan Buttar
            Pint

            Because of the Metric System

            "A Royale with cheese".

            And in Paris you can buy a beer at McDonalds.

        2. This post has been deleted by its author

        3. Anonymous Coward
          Headmaster

          19.3675cm?????????????

          I think you are actually refering to the SI unit of a metre

          So it's actually 0.193675 m

          (reposted after making a complete arse of the arithmetic)

      3. DZ-Jay

        @Robert Long 1

        Actually, we have two sets of 8 fingers with an extra pair to serve as "carry" and "sign" flags. We should be measuring everything in Hexadecimal--the only number system designed for humans.

        -dZ.

        1. Anonymous Coward
          Anonymous Coward

          face

          Very good, except toes aren't fingers.

          1. DZ-Jay

            @face

            I didn't count the toes each hand has 5 fingers.

          2. DZ-Jay

            @face

            Oh I see, I meant to type two sets of 4 fingers, not 8.

            -dZ.

    2. Anonymous Coward
      Badgers

      Back in the real world...

      Every Tv I have seen has had both size advertised for decades. But there is a real difference in what they measure.

      The imperial scale typically measures the tube/screen/panel size of the unit, where as the metric size must measure the picture size.

      This has been true since the 1980's at least, as it was a EU directive back then, but it only applyed to metric measuments.

    3. Martijn Bakker
      Happy

      Metric screen sizes

      Unfortunately even on the continent, where we measure everything else in metres, screen sizes are still measured in inches diagonal.

      This has contributed to the idea that while the exact size of a meter might vary according to the temperature, the imperial system varies with politics (and most would rather trust the weather).

      When 14" screens for office PC's were outlawed, the same screens reappeared on the market as 15" screens without increasing in size. That's apparently because someone decided that a screen diameter in inches didn't need to specify size of the picture area of the screen.

      So now we describe screen sizes in inches and we accept that an inch is generally somewhere between 2 and 2,5 cm.

    4. Dave Bell
      Boffin

      Making it easier

      For small angles, measured in radians, the tangent of the angle is equal to the angle.

      One minute of arc is 0.00029 radians

      For those into target shooting, this is one inch at 100 yards.

      It simplifies things a lot.

      Radians are defined by a measurement along the arc of a circle. For these small angles the difference between a straight line and this arc is minute.

      (I learned this at school, but I keep being told exam standards have slipped.)

  9. MJI Silver badge

    5 foot for 46" here

    And still seems a bit far at times.

    You can see the difference between SDTV, BBC HD & HDV, Games and normal Bluray.

    Use direct pixel mapping with 1920x1080p

    BBC HD looks a little less detailed - same as HDV

    Games are mainly I think 1280 x 720 - again looks good but slightly less detail.

    SDTV looks pants in comparison

    1920x1080p Blu Rays are best.

    I sit closer for games as well!

    1. Anonymous Coward
      Anonymous Coward

      BBC HD.

      I thought it looked less detailed, but then they broadcast a hd scan of indiana jones and it looked wonderful. I guess the hd cameras they shoot stuff on aren't any match for a decent film scan.

      ITV (STV in my case) looks far less detailed than ch4 / bbc hd.

      1. Malcolm 1

        TiVo

        I sit about 2m from my 40" telly and can definitely tell the difference between 720 & 1080 content (blu-ray is far and away the best).

        That said, I've noticed a distinct improvement upgrading from VirginMedia V+ (one of the old Scientific Atlanta boxes) to their new TiVo box thereby demonstrating the importance of the source. Also I can now get HD versions of many BBC3/4 programs via the TiVo iPlayer app.

      2. MJI Silver badge

        BBC HD is HDV resolution

        1440x1080i rather than 1080i of normal HD and 1080p of BluRay

      3. Chris Miller

        If you look closely

        BBC wildlife progs often have shots of the cameramen at work. You can clearly see 720p on the side of the kit.

        1. Anonymous Coward
          Happy

          @ Chris Miller

          "You can clearly see 720p on the side of the kit."

          As long as you're watching it in HD...:-)

          One is reminded of Amy Wong's naughty tattoo from Futurama.

        2. Frank Bough
          Happy

          Varicam

          The natural history film maker these days often favours a Panasonic Varicam, owing to it's excellent CineGamma features and 720/60p mode. Don't worry about it and just enjoy the pictures. 1080p cams are often used for establishing/aerial shots, DSLRs for timelapses etc etc etc

  10. johnnytruant

    I recently "downgraded"

    From a cheap 1920x1080 37" LCD to a nice quality 1024x768 42" plasma and can't tell the difference in terms of resolution. Picture quality is through the roof though.

    I'm buggered if I can figure out why the apparently square pixels on the plasma manage to have a 16:9 aspect at that resolution though.

    1. MJI Silver badge

      I went straight to top end LCD

      Not the poncy chassised ones, just where the money went on panel and drive electronics.

      Definate difference in picture between different LCD models

    2. Anonymous Coward
      Anonymous Coward

      re: I recently "downgraded"

      @johnnytruant

      XGA 1024x768 was a standard IBM computer display, particularly with built in hardware processing to offload video processing from the CPU. Using that hardware processing, could be a cheap option for plasma displays, that appear to have been mainly made for the US market.

      Plasma displays may not to be made with square pixels. So most non-square pixel plasma displays need to use additional processing as well as the 4:3 'scaler' that has been built into all digital receivers.

      Divide 1024x768 by 256 and you get 4x3, obviously not a 16:9 display if the pixels are square.

      The "apparently square pixels" cannot be square they must be rectangular - wider than their height in the ratio 4:3, to produce an actual 16:9 display

      For a non-square pixel display, a full 1920x1080 video being received would generally be transformed from 1920 by 4:3 into 1440 in each line, to change square pixels to display on the rectangular pixel display.

      Except that the UK transmissions on DVB-T/S are now generally compressed by the 4:3 scaler to reduce 1920x1080 to 1440x1080 etc - so such a compressed picture displays without processing if the pixels are displayed 4:3 shape rather than square.

      So generally the 1024x768 plasma display does not have to rescale the pixel dimensions, for UK HDTV.

      That leaves the built in processing to resize the picture, from 1440x1080 to 1024x768 - which is the same reduction in each dimension: (1024/1440)*1080=768 Rather than being done by a CPU this could be done by the cheap old hardware that was made for the IBM XGA displays.

      Compared to very early plasma displays that sometimes had to process broadcasts with three picture transforms, this 1024x768 plasma display is generally performing one resizing transformation, in order to reduce definition by about 30%, which should be noticeable. Depends what you are watching, at what distance, and all the other qualifications. You would probably notice a difference between your old 1920x1080 LCD-TV and the new 1024x768 plasma-TV if watching a Blu-ray 1080p video.

      However the better colour of new plasma display, compared to an old LCD display, is probably more satisfying for the moment, until the plasma display deteriorates with age.

  11. Anonymous Coward
    FAIL

    ROFL

    Much as it is often slated there is actually a very useful article on Wikipedia about Visual Acuity - it might have been worth a read before publishing this drivel - especially the section on 'Normal vision' which is NOT the same as 20/20 vision.

  12. johnnymotel

    square pixels all round

    Most broadcasters use 1440x1080 for transmission which is an anamorphic version of 1920x1080. That means it is 16x9 squashed to roughly 4:3 and then expanded again(similar to what they do to films on DVD). The scalers in settop boxes will do the conversion back to 1920 so the viewer never actually sees 1440. They do this because the slight drop in horizontal resolution (almost invisible to viewers on all but the largest displays at sensible viewing distances), saves some bitrate which in turn makes the MPEG compression easier (hence less coding artefacts). This is not a BBC only thing, almost everyone does it because it makes the pictures at broadcast bitrates look better!

    As for overscan, the 16x9 picture, which is now 1920 scaled from 1440, is completely overscanned on most TVs which means that even broadcasting 1920 and receiving on a 1920 display doesn't always give you pixel mapping, and you never see pixel mapped 1440 as that would be the wrong aspect ratio so everyone would look short and fat!

    1. Luke McCarthy

      My so-called HD camcorder does this

      I was shocked! shocked! when I examined the video files with ffmpeg

      1. MJI Silver badge

        Don't worry

        The best domestic ones are 1440x1080 on tape (HDV) rather than 1920x1080 on HDD or card.

        Resolution isn't everything.

        1. Anonymous Coward
          Anonymous Coward

          Re Don't worry & My so callled HD camcorder does this

          "The best domestic ones are 1440x1080 on tape (HDV) rather than 1920x1080 on HDD or card."

          There is an alternative, below the cost of professional movie cameras.

          A good reason for buying a DSLR or hybrid bridge camera is that some can shoot full 1080p at 30fps that's 1920x1080 pixels, generally with wider aperture lens and higher quality sensors.

          A Fuji HS10 can be bought for about £250 - mine produces stunning video even at the 720p setting

    2. MJI Silver badge

      Overscanning - not here

      I switched all HDMI connections to pixel mapping, Humax HDR rescales BBC HD, but I think the Humax overscans.

      Lot better picture

  13. Captain TickTock
    Pint

    Dr Who

    Still getting used to our new 40" HD set, upgraded from 26" CRT.

    Trying to get the right contrast and brightness right. Even films that got Oscars for the lighting look like bad 70s Dr Who...

    some things only time and beer will cure.

    1. MJI Silver badge

      Worth playing with

      Also try getting a setup DVD or BluRay - they work wonders.

      I set up my old CRT and the sharpness adjustment was a laugh - as it was 50Hz and RGB it was fully sharp with no edge enhancement - best for CRT by far, it only worked on non RGB and who uses that!.

      Sorted out brightness and contrast anyway on the LCD panel, Rest were fiddle with until it looked right

      1. Peter Gathercole Silver badge
        Boffin

        Setup DVD

        An alternative is to use a DVD or I believe BluRay disk produced with THX (like any recent Star Wars disk). This contains a setup tool called THX Optimizer

        On the menu screen, move the highlighted area to the THX logo, and press enter or play. You should find several setup tests for resolution, contrast, colour balance, sound and a couple of other things. To get the colour right, you really need a blue filter of a particular pantone colour, but you can get an idea without it.

      2. Nigel Whitfield.

        You may not need a special disc

        Quite a few Sony BD releases have test patterns, accessible by pressing S-O-N-Y when the main menu is on screen (that's 7669 if you don't have letters on your remote)

  14. NoneSuch Silver badge
    Unhappy

    Scary thing is...

    They are working on newer resolutions that are even denser.

    http://www.bbc.co.uk/news/technology-11436939

    256" TV in your future???

    1. Anonymous Coward
      Thumb Down

      If you have the living room on the pic - why not

      You will need to apply a bulldozer to your average 20th century build British house and rebuild it so it has the living room from the cute picture attached to the article. 90% of those have the sitting room with obstructions on 3 out of 4 walls preventing the sane positioning of anything bigger than 32 in. In order to fit anything bigger you either have to put it above the fireplace (wrong viewing angle) or remodel the ground floor in a more "modernistic" style as per the picture.

      1. David Paul Morgan

        get a sledgehammer out...

        I removed the gas fire & token fireplace, just to get one flat wall for my Panasonic 37" lcd. Gained floor space too.

        The installers re-routed the Freesat cable through the wall. Painted the wall licquorice brown, so the tv frame is camouflaged.

        Sources are Virgin hd & ps3.

        We sit 2.5 - 3 m away. Looks great.

  15. John King 1
    Pint

    Simple but effective. Top Tips (not Viz).

    Don't laugh but I do have a solution for people when choosing a screen size. Simply get some large pieces of cardboard with 16:9 ratios of a number of common screen sizes. Then plonk them in the corner of your room or above the mantlepiece, sit back and see if they're the right size for the room.

    It may seem silly but it has stopped people I know from buying behemoths that would swallow their living rooms or postage stamps that would give them eye strain.

    No, no need to pay me but you could buy me a pint.

    1. Malcolm 1

      Why above the mantlepiece?

      I never have understood situating the telly over the mantlepiece- it always seems uncomfortably high to me when sitting on a typical sofa - like sitting in the front row of a cinema.

      1. MJI Silver badge

        We have no fireplace

        So wins all round

        1. Joefish

          You're lucky.

          I have a rented place where they've done a Lawrence-Llewowen-Bellend and papered one 'feature' wall, then put in one of those B&Q electric fires with fake wooden fireplace surrounds.

          1. MJI Silver badge
            Pint

            Bellend

            Sorry that earned an upvote.

      2. Giles Jones Gold badge

        Fireplace

        They're freeing up floorspace by not having a TV cabinet but don't wish to get rid of their fireplace.

        I got rid of the fireplace, mounted the TV just above the gap and put three shelves in the gap where the fire was. Perfect height IMHO, although I do worry about the TV being so low that the dogs will damage it when playing (they're quite tall dogs).

    2. Anonymous Coward
      Go

      Right Size

      Mostly agree, and I know lots of people who have done this. But one extra piece of advice to consider:

      Once you figure out which size you (or more likely, the wife) think is the right size, go for one size larger (2"-3"), especially if moving from CRT to flat.

      Almost everyone I know has come to that conclusion a couple of weeks into their new TV. (Caveated with "this only applies to aethetics, and obviously not to physical limitations")

  16. M Gale

    Been saying this since HD came out.

    Not that I'm some luddite who doesn't like it. Just that most people don't sit with their nose touching the screen. From the other end of a living room, unless you have a super-sized screen (above, say, 25-28 inches), are you really going to tell much difference between HD and even a normal DVD? And no, I don't have crappy eyesight. It's good enough to see the "invisible" pixels on an iPhone4, at least.

    The biggest benefit I can see with HD, is that finally broadcasters have upped the bandwidth of their digital channels to approximate a level of quality achieved by standard analogue PAL several decades ago.

    1. MJI Silver badge

      Sit the other way

      Put TV on the long wall and sit opposite it.

      I hate watching TV diagonally.

    2. Annihilator Silver badge
      Paris Hilton

      "super-sized"

      "From the other end of a living room, unless you have a super-sized screen (above, say, 25-28 inches)"

      You've got an odd idea of super-sized if you think 28+ is massive? 25-28 barely counts as a PC monitor these days...

  17. goats in pajamas

    Broadcast dimensions

    For years I put up with an old screen and listened to conversations where, if I was lucky, I could see the tips of the noses of the people talking (lost the remote so couldn't put the screen into "letter box mode").

    Finally gave up and bought a "widescreen" 22" telly and now I regularly see the last couple of letters of the various BBC on screen logos with the rest off screen.

    The screen is set to auto detect broadcast dimensions and change accordingly.

    I don't understand.

    Mostly I don't care as Virgin's TV quality is appalling and the picture regularly breaks up into pixels and there's so little on that mostly we use it for Radio 4.

    But I'm still curious as to why.

    Are there two sorts of widescreen? Or is this down to incompetence by VM?

    1. Anonymous Coward
      Go

      Re: Broadcast dimensions

      Check your Virgin box is set up for a 16:9 TV. If the Virgin box is configured for a 4:3 TV, then it will be converting everything to 4:3.

      Try pressing the Wide button on your TV

      If that doesn't work... are you using a CRT? CRTs have a thing called "overscan" - they deliberately make the picture slightly larger than the screen, so you lose a little bit at the edges. There are boring technical reasons for this, to do with how CRTs work. Better CRTs have less overscan. Flatscreens don't have (as much) overscan.

    2. IanPotter

      RE Broadcast Dimensions

      My old Toppy was doing that for a while, turned out a firmware update + factory reset had set its scart output back to 4:3. Have you checked your Virgin box is set to the right aspect?

      1. Nigel Whitfield.

        Widescreen switching can be a nightmare

        I was mildly annoyed that after an update to the firmware on my Panasonic TV, it wasn't responding correctly to some of the WSS signalling from my Toppy, and 4:3 material was being stretched to fill the screen ("VulgarVision")

        It's been resolved in the end by replacing some of my other AV gear, so the Toppy is now running through a Yahama AV amp which upscales everything, and has control over black bars, so 4:3 material is correctly pillarboxed once more.

        Acutally getting the Toppy to respond correctly to all the various AFD formats was one of the most tedious and long winded updates we went through a few years back.

      2. goats in pajamas

        Virgin Box Settings

        Awesome bit of advice.

        The VM box was indeed set for 4:3 - now sorted.

        Many thanks for that.

  18. Jon 37
    Boffin

    Simpler maths

    Isn't it possible to simplify those formulas a bit?

    d = 0.7277 * sqrt(D * D / 337)

    = 0.7277 * sqrt(D * D) / sqrt(337)

    = 0.7277 * D / sqrt(337)

    = (0.7277 / sqrt(337)) * D

    = 0.03964 * D

    Removing excess precision, you get d = 0.04 * D.

    Or to put it another way, take your TV size in inches, and multiply by 4. You need to sit that many centimeters from the screen (or closer) to see all the details in a full HD picture.

    1. Nigel Whitfield.

      Yes

      You're right, we could probably simplify but a) don't all those fancy symbols look impressive and scientific? and b) how would you know we hadn't just made up a number?

      1. Jon 37
        FAIL

        Re: Nigel

        a) Yes. And if you show your working as you simplify it then you get to write even more fancy symbols!

        b) If you show your working then it can be checked.

        While TV shopping, I can do "multiply by 4" in my head. I can't do a square root in my head.

      2. Steven Knox
        Boffin

        @Nigel (b)

        But since the article states that you're working off a figure from a BBC survey, we KNOW that you're working with made-up numbers!

    2. Anonymous Coward
      Dead Vulture

      Simple maths!

      Really, this is supposed to be connected to the technical Internet! The equations are all wrong.

      sqrt(D*D) != D

      sqrt(D*D) = abs(D)

      (This makes a different if I'm watching your TV from the flat next door. I wouldn't want you to waste your money on a -60" TV, that's too small).

      1. Annihilator Silver badge
        Boffin

        re: Simple maths!

        sqrt (D * D) != abs(D)

        sqrt (D * D) = +/- D. Or I think you were probably aiming for abs(sqrt (D * D)) = D

        1. Jon 37
          Headmaster

          Re: Simple maths pedants

          Annihilator: The sqrt() function is normally defined to return the positive square root of a number. So sqrt(D * D) = abs(D), it's not +/-D.

          Anon: D is the distance from the screen. Having a negative distance doesn't make sense (you can only see the picture from one side of the TV!). So we know that D > 0. So sqrt(D * D) = abs(D) = D.

  19. Anonymous Coward
    Anonymous Coward

    (Assuming we're talking digital sources here)

    Resolution is nothing. Quantisation artefacts are everything.

  20. The BigYin

    Give me...

    ...an HDTV that is as dumb as a dumb thing with maybe just a couple of HDMI/component connectors. That's all I need. I'll plug low-power PC into that and it can do all the network/fancy stuff. This also means I can control what content gets shown, how it gets shown and what codecs will work; not have to suffer some broken, OEM-only content restricted bull-crap. The orther connectors would just be for consoles.

    Hmm...I could probably route them through the PC...

  21. ThomH

    42" EDTV here

    Yes, you know, the 480p sort. It was a hand-me-down gift. I probably sit about 3 or 4m away and can see the pixels on any high contrast objects. But I don't really care.

  22. A Non e-mouse Silver badge
    Stop

    Content is king, not TV

    I have a cheap 'n' dirty LCD TV (not big, about 28 or 32") Bought before the whole HD hype. My Virgin cable TV gives me some HD channels for free.

    The picture quality on the HD channels is miles better than on the standard def channels - even though I'm viewing both on the same cheap standard def TV via a boring SCART connection.

    I think this shows that it's not really the TV resolution that's the killer (althought that does help) but it's the bandwidth of the source material. If the material is compressed as far as it can go, then it'll look crap on any TV. Add a bit more bandwidth, and we can all get more quality without spending a penny on a new TV.

  23. Anonymous Coward
    Alert

    HD TV and Xbox Kinect...

    What's the distance recommendation for using a Kinect?

    So, now how big does your TV need to be?

    Answers on a postcard.

    1. Peter 82
      Alert

      kinect = 6ft or 1.8 metres

      Therefore you need at least a 45" TV and that's for one person

      Apparently for 2 people to be playing you want to be 2.5 meters away means you need a 62"

      1. Anonymous Coward
        Happy

        you need a 62"

        Ta. that's enough justification for me.

        Let's go shopping...

        (what do you mean that's not what the article intended..)

  24. Trollslayer Silver badge
    Thumb Up

    58" 1080p TV, 3.5m

    That is just right for me and yes, 1080p makes a difference.

    It is a good Samsung plasma, if you have a poor TV that can take away the benefits of resolution.

  25. Patrick R
    Stop

    All those questions...

    What about the last one; how big do YOU want your TV to be ? Because your questions will all be worthless each time the bradcasters change resolution. Should we buy a bigger TV each time ? Or a bigger house ? Now for math, you could have put the effort to set a small table with all standard values. I'll begin for you;

    32", 720p, pixel size: 0,558mm, distance for 1' angle/pixel: 1.92m

    32", 1080p, pixel size: 0,372mm, distance for 1' angle/pixel: 1,27m.

    Cheers.

    1. Anonymous Coward
      Happy

      size matters...

      how big do YOU want your TV to be ? I think you mean:

      How big does your WIFE want your TV to be ?

  26. James Thomas

    Upscaling is important too

    Compression is important, but if you're watching SD material on an HD set the upscaling and filtering also makes a massive difference.

    I use an HTPC using DXVA for rendering with carefully chosen codecs, and 0 TV scaling (since the PC always outputs 1080p) and watch Freeview. All sources look great, with artifacts greatly reduced. OTOH my friend's Sky+ on an equally sized TV looks, frankly, like shit with tons of artifacts and blockyness.

    Properly upscaled SD material on an HD set can look a lot better than native SD, even with the crap bitrates some channels use.

    Btw. I sit about 1.5m from my 42" and I'm pretty sure I could tell the difference between 720p and 1080p. I never understood why people by massive sets and then sit miles away from them.

    1. Anonymous Coward
      WTF?

      Help!

      El Reg

      Can we have a terminology guide, that last post was just gobblydegook

  27. Glyn 2
    Megaphone

    Oh, now we know

    All this argument , claim and counterclaim is why when my telly died last week, I went and bought a second hand CRT from the charity shop for £30.

    Call me when they've sorted it out and there's one thing to buy at a reasonable cost which isn't going to be superceded by something else in 6 months time...kinda like my old telly.

    And if dvd producers would stop putting the subtitles in the black border on the bottom of the picture, that'd be nice, then when I'm watching something I can tell what the frenchman/american/alien said.

    1. Jedit
      FAIL

      Welcome to the 21st Century

      If you're waiting for a time when TVs won't be superseded by the next generation in six months, you will never buy a TV again. Just buy one you think is really good and use it for three years or more, like everyone who doesn't feel the urge to condemn rapid technological development as a bad thing.

    2. ThomH

      Re: subtitles

      You've probably got your DVD player or Freeview player or Sky+ box or whatever set to output a 4:3 picture, so it's letterboxing the 16:9 then putting subtitles on at the bottom. Probably things would improve if you set the box to 16:9, adjusting your TV's picture stretching setting accordingly.

      1. Glyn 2
        Boffin

        subtitles

        "If you're waiting for a time when TVs won't be superseded by the next generation in six months, you will never buy a TV again. Just buy one you think is really good and use it for three years or more, like everyone who doesn't feel the urge to condemn rapid technological development as a bad thing."

        Then I'll never buy a TV again and I'm not the only one. The sales figues for tvs are worrying electrical retailers as people who don't want to spend £££ on the never ending merry-go-round of the next big thing are not buying. We've gone from CRT through LCD, plasma, HD, Freeview, more HDHD, bigger and bigger and now it's 3D all in only a few years.

        People bought a tv when their old CRT died and while some have swapped once, only gadget show fans have updated to the latest tech every 6 months.

        "just buy one you think is really good "

        How? What criteria am I using? In the shop each screen looks different most of which is apparently due to the transmission cable the shops use to transmit to all the screens. So I can't compare screens. Also there's no sound, so I can't compare the audio quality. So that leaves me with a stream of numbers and technical specifications which mean nothing and when you look on the net or in magazines for advice you get diametrically opposing views on everything.

        For example I've been told that for games I *must* have a plasma as <insert technobabble here> and I *mustn't* have a plasma as the HUD from my favourite game will get burnt into the screen. So, who do I listen to?

        Repeat for every other technical aspect of the television.

        "use it for three years or more, like everyone who doesn't feel the urge to condemn rapid technological development as a bad thing."

        This is not a luddite thing, the rapid technological development you love isn't development. Stuck my old CRT next to my mates HD tv with Halo Reach on both. No discernable difference in the picture quality.

        Mum went to currys (other shops are available) and bought a telly when their CRT one died. This was 3 years ago and they're on their 3rd tv now. They keep dying, blocks of red pixels, power not working, etc. They're under guarantee so they keep getting given new ones. It's hardly inspiring me to spend upwards of £500 on something that seems destined to break.

        So why should I buy a telly that isn't that much better and that'll only last 3+ years when my old one lasted 13+ ? Please explain to me how that is "technological development". An identical product that doesn't last as long as the previous iteration is regression, not improvement.

        As another example take DAB which has been set as standard here, but there are other better DAB versions now so we're told we should use an upgraded system and the government is wasting money on DAB. When does it stop? Do we role out a new transmission network every year and people have to buy new kit every year to access it? The old analogue system has been around for how long again?

        I could just as soon call you a gadgetfreak with too much money/credit for buying into the merry-go-round, pointless blanket insults aren't helpful are they!

        1. Jedit

          You're right, you don't need a new TV

          If you can't tell the difference between 1080p and 625 lines analogue, then you're either blind or partially sighted.

          So your mother had bad luck with TVs; that's a shame, but one piece of anecdotal evidence does not mean all modern TVs are crap and unreliable. My own mother picked up her HD TV about the same time yours did, and it's worked perfectly since the day she got it. Guess that means all HD TVs are good, right?

          As for your "pointless blanket insults", it was good of you to check that I have a 3D TV before calling me a gadget freak with too much money. Oh, wait, you didn't - you just jerked the knee.

          Now as it happens, I actually do have a 3D TV. I saved for it for half a year and I bought the best TV I could afford. I also paid for a 5-year extended warranty on it. Know why I planned this way? Because I don't "buy into the merry-go-round" - I intend to get full value for my money and use that TV for five years, if not more.

          1. Glyn 2

            glasses, 3d or otherwise

            As you've not seen the tvs in quesetion, you can't really comment on our visual acuity. If you have a small screen, you don't need HD. The HD is there to fill the blanks in on your big screen.

            Exciting ascii art diagram - this is how a pixel looks on a CRT tv

            #

            this is the corresponding area on a big HD tv viewing SD

            @@@

            @#@

            @@@

            the HD fills in the @s and smooths the edges so you see

            / -- \

            | # |

            \ -- /

            with nice curved edges that you had on the smaller CRT.

            My mum's was an example of technology failure, about a third of the people I know who've had new tvs have had problems of one kind or another, some as minor as a few dead pixels, others DOA when they took it out of the box. Others had various breakdowns and failures over the next year.

            Old tvs, no out of the box failures, very few problems until tv the tv died totally many years later.

            The new TV tech is too delicate, which suits the manufacturers just fine because they can sell more of them. 1 CRT tv lasts as long as 3 new tvs so you can go and spend more money with them.

            No jerking of knees or elbows required.

            "like everyone who doesn't feel the urge to condemn rapid technological development as a bad thing."

            This is the kind of thing only people who've spent or are going to spend a lot of money on a gadget say...and you have.

            So you had a CRT before? Bought a bluray player? Bought sky HD/3D?

            And you bought the extended warranty, more money spent but which is now essential as they break. Extended warranties have been a cash cow for retailers for years as the percentage of people needing to make use of them was very low and consumer bodies recommended not buying them for anything. With new tvs it's a must have and the same comsumer bodies say you *should* get an extended warranty for your shiny new one. Surely that proves their fragility and unreliability.

            1. Jedit
              FAIL

              No, actually it doesn't

              Preparing for the worst does not mean that the worst is going to happen. It just means that if it does, you're covered and hence do not have to come to El Reg forums to pule and whine about your terrible experiences.

              1. Glyn 2
                Heart

                hmm

                If the worst that can happen has a vastly higher probablility of happening sooner with the new (with such a high probability that you have to take out extra security) then the old is better. Maybe not technically, but stability wise, certainly. Insurance for an 18 year old driver is £3000, for a 30 year old £300 as the 30 year old is less likely to crash.

                It's like saying that rock climbing is safer than climbing stairs because you've had to rope up to go climbing. The need for a safety net doesn't make the new better.

                Forgive me for wanting to buy something that doesn't have a high chance of breaking before the year's out.

                As for "pule and whine about your terrible experiences"

                1 - they aren't my experiences because I haven't bought a new telly

                2 - I refer you to your original post whining that I'm a luddite

                3 - my original post was bemoaning that there are so many bits of technical information and varied opinions on how to interpret them and updated versions of it all, it's hard to know what to buy so you're not left with an HD-DVD collection when you should have bought bluray

  28. F'tangF'tang

    sixty

    I had a last generation Pioneer 50", and the difference between Sky SD and HD was minimal to say the least (might be because the Pioneers had pretty good inbuilt scalers)... With the Pioneer 60" it was much more noticable... HD is good, and I have it...but I could live without it...

    Its strange how they shrink tho... I took the tape measure out more than once to double check the size...

    Thats sitting 10ft from the screen btw...

  29. hexx

    all depends on your vision

    you can use 'retina' calculations to calculate the right size of a tv for your room and depending on the content you mostly watch. you can use wiki or other sources to get it right. from my findings it looks like THX is using calculations based on 'retina' of human eye as they usually state closer viewing distances than others. on my 40" while watching 1080p source i can't go closer than 1.2metres, i start to recognize pixels, my vision is ok, not perfect but don't need glasses. for SD content i need to be at least 3 metres away from the screen. so it really depends on the content and your vision.

    1. Anonymous Coward
      Jobs Horns

      Retina - that's only one factor.

      Don't listen to the snake oil salesmen! Your visual acuity is dependent on a large number of factors (as any photographer or optician knows), aperture (iris) size, lens quality, ambient light conditions, display brightness, whether the display is reflective or emissive to name but a few. The resolution of your retina at its finest point (yep, it isn't uniform) is only one factor of many.

      1. hexx

        yep

        that's why i suggest ppl to do their own observations with existing gear to work out what's best for them. i used to sell projectors and never really understood my customers wanting huge screens and viewing distance wasn't far enough and it was at the times HD was just starting.

  30. Cyclist
    FAIL

    Bedroom

    A former colleague (young lad, first proper job, bit of spare cash) tootled off to one of those warehouses to buy himself a new flat-screen TV. When it came to paying the salesboy did a decent job and talked him into buying it on credit, then pointed out that he could now afford a much bigger screen. Result? Young lad, tiny bedroom in his parents house, 50" screen. Neck-ache or what? It works both ways y'know.

  31. Gareth Perch

    Beamer

    My projector screen's 100" (2.5m) and I watch it from just under 4m away. I don't need a TV, just a PC and pj - I can watch all the (mostly US) TV shows I like on that.

    I saw a post somewhere that had a BluRay 720p image blown up to 1080p dimensions, vs an actual 1080p native image from a BluRay and I could barely tell the difference, and although my eyesight's not great, this was from close up.

    Perhaps I'd be able to tell the difference on an actual BluRay disc if my pj was 1080P (it's an Infocus 7210 which has the DarkChip 3 technology, which was pretty good a few years ago when I bought it and is still going strong).

  32. Lloyd
    WTF?

    But anyone with a flat screen tv would already know this?

    You'd do your homework before buying surely?

  33. Anonymous Coward
    Anonymous Coward

    So why oh why

    Don't broadcasters stick to 1280x720p50 rather than the hideous 1440x1080i bodge?

    The former is immune to interlace artifacts, has more temporal resolution, the spatial resolution is not significantly worse, and it may compress better.

    1. MJI Silver badge

      Possibly historical

      They are exactly the same settings as used by HDV.

  34. MikeyD85

    Far too much work there

    I've a much better method:

    1) Find your spot for your TV

    2) Buy the biggest thing that'll fit / you can afford

    Simple.

  35. Alan Brown Silver badge

    cheapie lcd

    22" and I can clearly see the difference between SD, SD(upscaled) and HD

    Then again I only sit 75cm from it most of the time (It's on the wall above my computer monitor)

    Corner placement only made sense for Tvs when they were bulky and had long rearward protrusions - ie, they were the only spot you could put the things and not lose too much space.

  36. juice Silver badge

    HD/SD comparisons

    I did a fairly basic comparison between 1080p Blu-ray and 480p DVD, using the Up! combo back - the Blu-ray went into the PS3, the DVD went into the Xbox 360 (which upscales it) and both were shown on my 40" 1080p TV.

    And... yes, there was a perceptible difference in visual quality. It was slight, but it was definitely there.

    But. Was it enough to affect my enjoyment of the film? Not in the least.

    Overall, it confirmed my previous sentiments. Generally, I'll be sticking to DVDs - aside from anything else, they're usable pretty much anywhere, whereas relatively few laptops/relatives/friends/bedrooms/etc have a blu-ray player. The only exception is where the "combo" pack is cheap enough, or where it's an animated or CGI-heavy movie, as I think animated graphics do significantly benefit from the higher resolution.

    (on a similar note/rant: has anyone done a "blind" test with 3D technology? I'd love to see the results of sitting a bunch of people in front of a cinema screen, giving them 3D glasses and sticking on a 2D version of something like Avatar. I suspect a significant percentage would swear the 3D effects were amazing...)

    1. EvilGav 1

      No

      DVDs are not 480p, they also aren't 576i. These are resolutions that came out a long time after DVDs started out.

      A reference encoding on DVD can have around 700 vertical lines, i.e. closer to 720p. The DVD reference standard exceeded broadcast quality when it was introduced, 480p and 576i are frequently misquoted as they roughly equate to the NTSC (525 lines, minus 50 for data) and PAL (625 lines, minus 50 for data) picture standards.

      Disney have always been meticulous with their DVD encoding, hence an upscaled DVD doesn't look that much different than the BD, as the difference is between 720p (roughly) and 1080p.

      As for enjoyment of the film, that will, invariably, be based on whether you like the film or not and have nothing to do with the image quality.

      1. GFK1
        FAIL

        Bzzzt

        Yes, they are. Suspect you're confusing vertical lines with vertical resolution, not at all the same thing. DVD's are mpeg2 encoded at either 720x576 or 720x486 generally. I can also assure you those resolutions were in very common use in broadcast behind the scenes well before DVD came along. Google "D-1 sony" if you don't believe me.

        1. Stuart Halliday
          Happy

          we don't see the quality

          DVDs may be encoded at 720x576. But most budget films come from a USA master tape that is only at 500lines NTSC. Old BBC analogue programmes have only got about 500 lines PAL resolution.

          Then they took a 16:9 film, squeeze it in horizontally to fit into a PAL frame and then expand it horizontally to fill a 16:9 sd TV. My old high-end 32" Panasonic widescreen crt displays about ~600lines. So still not showing me full PAL resolution.

          DVD is not capable of showing me full PAL. It wasn't designed too.

    2. F Seiler

      re your rant

      The only 3d-display experience i have is from CAVE (http://en.wikipedia.org/wiki/Cave_Automatic_Virtual_Environment), and there i always felt disappointed, until one day during setup i saw it cycling through setting for different assumptions of eye-to-eye distance. At about twice the usually assumed distance it looked amazing, though definitly not "right" :)

      So i'm definitly not blind to that "3d" effect but my brain seems to automatically expect anything on a screen to be 2d (resp. ignore "3d" if it is) unless it is severly exaggerated (to the point where i would get sick had i to sit through a whole movie at that setting).

  37. Nigel Whitfield.

    Showing the workings

    If anyone wants to check the maths, the working out is all on show over on my blog:

    http://gonedigital.net/2011/05/19/showing-the-workings/

  38. Neil Barnes Silver badge
    Boffin

    But you're asking the wrong question...

    It's all very well speaking of the size of the pixels - but if you're not watching something whose format matches the resolution of the viewing device you're at the mercy of the upscaler. Which ought to be a piece of cake these days - I'm old enough to remember when standards converters took three 19" racks - but, for example, the upscaler in a Humax box is significantly better than the one in a Toshiba TV

    And of course, you're watching a *seriously* compressed image anyway, in most cases. A full-bandwidth SD image pushes 270Mb/s a second but is transmitted at most at two megabits or so - variable due to statistical multiplexing - so there's a lot of information which the codec hopes you won't notice is missing. (Hint, watch the snooker on BBC 2 sometime - a beautiful detailed picture until someone moves and then it's covered with jpeg artefacts.) Some of the commercial channels are broadcasting at under 3/4Mbits/s, and look it, irrespective of the display.

    HD images run to 3 gigabits a second and are compressed - even on the BBC - to around 10Mb/s - a compression ratio of 300-1. Even Bluray only has fifty megabits a second or so in the stream - so whatever you're watching, it's unlikely to be showing everything that's theoretically visible.

    An interview with Andy Quested at the BBC might be interesting.

  39. Prive8 Citizen

    720 .vs 1080 in my case

    Our first HD set was a 50" 720p plasma. It hung on the wall about 10 feet from where we sit. We loved it - and the picture was stunning. However, I kept hearing about how much better 1080p was, so a few years later, we bought a 52" 1080p plasma. It's also beautiful, but frankly I can't tell the difference. The 1080p unit is now the living room unit, and the 720p unit is the downstairs unit, but I pretty convinced I could swap them and the family would never even notice.

  40. xyz

    My girlfriend cannot watch Emmerdale or Corrie in HD...

    ...because you can see every crease (crevices) in everyone's faces, so we have to watch it in 576i (or whatever it is) as they look ancient and HD spoils her enjoyment.

    This is on a Bravia 40" LCD via Freeview and we sit about 4-5 feet from it. You can tell the difference watching football big time. No artifacts if you switch from normal to the HD channel version.

    I've also turned down the settings (sharpness, brightness, backlight) so those blocky "blokey" Dave type channels (god bless 'em) have there arses covered display wise.

  41. JDX Gold badge

    At the end of the day, it's program quality not picture quality that counts.

    So you presumably use a 21" CRT. In black & white. With a portable aerial.

  42. WFW
    Stop

    Times two error in resolution?

    'The generally accepted figure for human visual acuity is one minute of arc, so we need to calculate the distance at which one pixel is equivalent to that.'

    We want the minimum distance to _not_ see pixels, so you want the distance at which one pixel is 1/2 arc-minute (or less).

    1. Anonymous Coward
      Anonymous Coward

      That's for 20/20 vision

      The one minute of arc figure is for 20/20 vision which is the lowest level of visual acuity that is considered acceptable before corrective optics are needed. Normal visual acuity is better than that so you probably need to go even narrower.

  43. Anonymous Coward
    Happy

    Size of screen has nothing to do with resolution

    Size of screen, resolution, and distance I sit away are largely independent factors. I buy HD for the simple reason that with all other things equal it looks better, but doesn't really cost any more. For distance I sit away, that is largely a function of the geometry of the room. Size is easy as well. I get the smallest size which my wife won't complain about being too small. That is currently 52" (although I get some complaints about the size of that). My view is that too big for your room looks stupid (when it is turned on or off), too small is just irritating. We don't size cinema screens because of the resolution, we size them because we want a big ass screen to watch movies on.

  44. StooMonster
    Thumb Up

    Ivor Biggen

    120-inch screen via 1080p projector, viewing distance is sat 5 metres away.

    Even 720p stuff looks not that bad, but 1080p sources like Blu-ray are excellent and broadcast HD is nearly as good.

    Games consoles are also super fun at this kind of size.

  45. Eddie Johnson
    Badgers

    Next in the Series

    I eagerly await a study of how 4:3, 16:9 and 2.35:1 aspects relate to how the human eye works. I'm convinced 4:3 is the best aspect for how our vision works and I despise looking at life thru a gun slit - or watching a 2.35 production. It sucks you can hardly buy 1600x1200 monitors anymore, the shortscreen crap has taken over.

  46. druck Silver badge

    46" at 10'

    I've got a 46" Samsung TV and sit 10' away, my Humax HD recorder allows watch a HD channel and send either 576, 720 or 1080 line resolution to the TV. Even with my tired 43 year old eyes, I can quite clearly see an improvement in detail between 720 and 1080, and enormously so over 576. Now obviously the lower resolutions have to go through two lots of scaling, but if the original content is 1080, it makes sense to watch it at that resolution for the best results regardless or optical resolving theory.

  47. Anonymous Coward
    Welcome

    ELO

    Are the 15% that can tell the difference (as mentionned at the bottom of page 2) the same people who see the rainbow effect with DLP projectors?

    I think I'm both but maybe could be coincidence.

  48. Anonymous Coward
    Happy

    whatever porn shows up best on

    'nuff said.

  49. Anonymous Coward
    Thumb Up

    Go big, or go home.... your home, not mine.

    We have a 40" 1080p TV in our bedroom, a 55" 1080p TV in our living room, and a 55" 1080p TV in our playroom. All are Samsung LED Series 6 and 7's.

    Does it make a difference? Hell yes. My wife and I definitely see the difference.

    We sit an average of 2m away from our playroom TV (comfy Lay-z-boy recliner loveseat - love it!).

    We sit an average of 3.5 away in our living room. Again, love it.

    We lay an average of 2m away from our bedroom TV. No surprise here - we love it, but keep thinking we should have gone bigger. Perhaps mount a 55" on the ceiling beside the mirror ;) Joking about the mirror, BTW.

    We are obsessed with knowing which resolution we're watching, but we turn it into a game, and try to figure it out. SD - no troubles there - easy to tell. 720p vs 1080p, we can see a difference, but it's not as great a difference as 480p vs 720p.

    We watch digital TV, Blu-rays, and play our PS3. We watch Netflix. We also have computers connected. I love the large real-estate and small icons 1080p provides.

    I work with optics on a daily basis, and I consider my eyes to be highly keen. To hear my wife say "oooooh, nice picture" every time we turn on one of these TV's brings a tear to my eye - I have found love, 5 times - my wife, our son, and our three TV's.

  50. Anonymous Coward
    Anonymous Coward

    Crap progams in HD

    are still crap programs.

  51. pootle

    front projection - it's the only way to go

    80" screen from a 1080p projector viewed from about 10ft. Yes, Blu ray is clearly better than broadcast HD, even dvd often looks better than bbc hd, but it does depend on the content quality of both sources.

    iPlayer HD works pretty well too - usually a bit better than broadcast sd as long as there's not too much fast movement, but only through sony blu-ray player. iPlayer through our humax freesat box is unwatchable.

    PC quality is good, but the blu-ray player is slightly better - mostly because it pans more smoothly.

    The cheapo channels (never watch em anyway) are pretty dire. Of course you do need a darkish room for good viewing, but with bright, high quality 1080p projectors available for around £1,000 I really don't see the point of big screens.

  52. Leona A
    Happy

    all very well...

    but if you have eye slight like mine (2/60), sit any further than 2 feet away and I can't see the thing at all, it doesn't matter how big it is.

    Any visitors to our house say, "your sofa is too close to the telly". Its about a meter away for my partner to sit on, whereas I have to sit on the floor right in front of our 42" HD Plasma.

  53. Chris Evans
    Thumb Up

    All HD does is reduce visble MPEG compression artefacts

    All that info confirms to me that effectively all HD does is reduce visble MPEG compression artefacts.

    I've yet to see a TV shop display an HD display next to a non HD of the same size showing the same program with the appropriate source so you can compare HD and non HD properly.

    i.e. If they used less compression on non HD then the 'higher res' of HD would be unnoticeable when viewed at anything approaching a normal distance for the screen size.

    Sounds a bit strange that everyone seems to view their screen at the same 2.7M I thought the whole point of large screens was for bigger rooms where you sit further away.

  54. DarkEnergy
    Thumb Down

    Wrong Assumptions Nigel Whitfield!!!

    A common mistake is to confuse resolution with sampling. To reproduce the RESOLUTION of a normal eye (~1 arc minute) with a digital display device what is needed is slightly more than 2 pixels per resolution element according to the Nyquist–Shannon sampling theorem and not 1 pixel per resolution element.

    In other words, you do not want to resolve the screen and see each screen pixel. What you need is to match the screen resolution to the eye resolution. The theoretical maximum screen resolution of ANY digital screen is given by the number of pixels divided by the Nyquist factor. In the case of HD would be 1920/2.3=830 in the horizontal direction. This is the resolution you need to match to the eye resolution of 1 arc minute. The eresulting distances to the TV screen are therefore 2.3 times larger than the ones you quote,

  55. N13L5
    Linux

    for computer use...

    You think viewing a 37" screen at a 24 inch viewing distance is alright, when using it as a computer screen...?

  56. F Seiler

    reporting in

    D = 0.988m for my 25.something" (H=345mm measured) 1920x1200 (0.2875mm high pixels) computer display i watch TV and most movies on.

    For other things i sit about 0.6m from it, but leaning back for movies gives 1.10m, well close to what the formula tells me to do.

  57. Jim Wilkinson
    Thumb Down

    Alias anyone

    All the calculations are related only to pixels. But pixels do not translate directly to resolution because Nyquist theory gets in the way. A number of factors will come into play in trying to work out how to balance maximising viewable bandwidth against the avoidance of alias frequencies. If screens have a high enough number of pixels than is needed for display, then alias becomes a non-issue. But if you receive a genuine (i.e. not up-converted) 1920*1080 picture, then a 1920*1080 screen cannot show all the resolution available in the 1920*1080 picture. The actual displayed resolution will be reduced by a certain factor - let's say 75% H and 75% V. This means that what the screen can present is lower than the calculations shown.

    The unrealistic way to get near to the screen resolution is to down-scale super-sampled source pictures (say 4096*2160) to 1920*1080 and then up-scale back to 4096*2160 at the receiver. Ridiculously expensive of course so it's not done (at least not yet). That said, it's why SD pictures look so much better on an HD screen than on an SD screen. The point is that a bit of over-scanning helps to get a better result. The calculations in the original post do not make that point.

  58. Chris Evans

    Jim: ..1920*1080 picture, on a 1920*1080 screen problem?

    Err.. I'm lost how can a "1920*1080 picture, on a 1920*1080 screen not show all the resolution available in the 1920*1080 picture"?

    Also I've been told that often SD pictures upscaled for an HD screen can look a lot worse than when displayed on an SD screen. Unless the upscaling introduces effects like antialiassing that is surely impossible, and those effects don't suit some sort of images/motion. e.g. antialiasing a picture of a saw blade may antialias away the teath!

    1. DarkEnergy
      Thumb Up

      A 1920*1080 picture does not have 1920*1080 resolution.

      The resolution of a 1920*1080 picture is less than its number of pixels. This is what I was trying to describe in my previous post.

      A 1920*1080 picture can only resolve 1920/K * 1080/K regularly distributed elements where K is larger than 2.3 according to the Nyquist theorem.

      Just do the experiment of taking an image of 1920*1080 regularly spaced holes in a back illuminated plate.

      Because the number of bright spots is the same as the number of pixels, the light from each hole will fill each and every of the available pixels and the resulting image will be completely uniform, no structure will be detectable. To RESOLVE a such a distribution of holes you need black pixels between the white pixels to detect the black spaces between the holes in the plate. i.e. twice as many pixels.

      Conclusion to resolve a 1920*1080 distribution or image you need a display of at least 3960*2160 pixels.

      Sampling is not the same as resolution!

  59. Stuart Halliday
    Unhappy

    Bring back quality

    PAL full spec is 768x576. This is usually shot in camera at 720x576 and clipped down to 700x540 by the time overscan on your TV is taken into account.

    In the days of VHS this was recorded at ~240x500 and didn't look too bad as TVs were pretty poor at displaying high resolution analogue TV. When TVs started to get better VHS started to look worse so we got SVHS at 400, hi-betamax at 500. Then DVDs came out capable of showing 500 lines. Still quite poor and soft when compared with a real PAL picture in the studio.

    I was stunned when I visited a BBC studio and saw the quality of PAL live on BBC professional TVs.

    The only time I got this quality was with BSB with their full RGB route from camera to my SCART RGB socket. I could actually see every gradical line in their testcard! Then digital TV came and quality went into the guttet. No wonder no one broadcasts the testcard any more... Too ashamed.

  60. Steev Wilcox

    Flaky maths

    Are you really suggesting that I should trust the maths of someone who writes "28.65 sqrt( D^2 / 377)", and doesn't realise that this is actually just 1.56*D?

    OK, so I've got a maths degree, but REALLY people ...

  61. Hooksie
    Megaphone

    Suck it and see

    Really interesting debate, went off topic a little but thankfully back on track. Just wanted to add my tuppence worth:

    720p for screen sizes 32" - 39"

    1080p for anything above

    I upgraded from a Sharp 42" LCD to a Panny 50" Plasma and found that my wife and I both felt more comfortable closer to the screen. This is no doubt due to many factors, not just one. It's all down to personal taste. The arguement was always about safety back in the day; how close could you be without damaging your eyes. But still the actual 'litmus' test is exactly the same. If you can make out an actual pixel, you're too close; if you have to squint and can't read the credits at the end, you're too far away - job done.

    As for other nonsense; not ONE broadcaster in the UK (or anywhere to my knowledge - open to correction) broadcasts in 1080p - 1080i is the most you'll get. Once you understand the difference between a progressive and interlaced picture you'll see that 720p and 1080i are not noticeably different to the human eye. (and yes, that's purely annectodal and has no basis in science - ok, maybe a little) Add to that the fact that the vast majority of HD TV's have built in upscalers or other such trickery and basically all of your home tests are for squat. I liked the guy/girl talking about hooking up an XBox to a CRT and an HDTV and not seeing any dfference. News flash mate - your buddy's HD TV is either fooked/shite or you're not using the right connectors. Try a PS3 on a CRT vs an HDTV.

    Anyhoo - according to the BBC's own documentation and experiments one of the most crucial factors in people's enjoyment and appreciation of HD content is actually focusing. Odd I know, but on an SD picture on a 28"CRT the focus can be quite a bit out and your brain just fills in the blanks. But on an HD broadcast on a big screen the focus being out just a little can make the picture look worse. And of course you have cameras, compression methods etc etc. See first series Torchwood in HD and then most recent Doctor Who HD broadcast for comparison. The former was broadcast at a higher bandwidth than the latter but looks like poo when stacked up against the Doc. That and wildlife docs look better than both of those.

    One final note to the lady whose mum had the trouble with the TV's and who is still using a CRT - I presume you have a coal fire, drive a 1982 vauxhall corsa and don't trust iron's because they break down? Stuff gets better and it gets most complex therefore more shit breaks. It's called entropy and applies to the entire universe. Go buy yourself a 50" LCD (forget LED cos it's a gimmick and plasma is, trust me, not for you - you'll have burnt the screen in a week and tell me it;s my fault) try to get a decent one -better response time = better image and find one that you like it the shop. Don't worry about "the colour looks better on that one" - grab the remote from the spotty tennage salesperson and mess around with each one until you're happy. Oh, and FFS spend more than £500 if you want it to last more than a year. As with the old CRT's, you get what you pay for.

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