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Resolution plasma 852x480 vs resolution PAL 720x576

Discussion in 'Plasma TVs' started by Swa, May 6, 2005.

  1. Swa

    Swa
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    If have noticed that the more payable plasma's (like the panasonic 37pa50) all have a resolution of 852x480. PAL (the format for dvd's) has a resolution of 720x576. So those plasma's have 16% less horizontal lines as the PAL-format! Will this lower resolution of the plasma's have a negative influence on the PQ??

    I know that you can buy higher resolution plasma's which can be used for HDTV when this is available. But I don't want to invest in HDTV yet because:
    - it will take a while before HDTV is mainstream
    - the maximum HDTV-format is 1920x1080 and those resolutions are not available or to expensive

    So my question is: if you use non-HDTV material (like the normal DVD's and cable TV), will the PQ of a plasma with a resolution of 852x480 (for example the 37pa50) be less than a plasma with a resolution of 1024x768?? Is this a noticeable difference, is it worth the extra money?

    Thanks for your help!!
     
  2. laser

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  3. Orangelo

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    Although it is true that PAL DVDs are 720x576, you need a 1024x576 panel to view the full content with the correct aspect ratio. With a 480p panel, you are missing both horizontal and vertical information.

    The difference in resolution is hard to notice with films unless you can do a direct A/B comparison, but becomes very obvious with a test pattern.
     
  4. hornydragon

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    Plamsa are not like PC monitors they sacle all incoming video to native res, its more important to have good scaling than lots of pixels.............
     
  5. EN

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    The difference is very obvious.
    Last mount I was going to buy a SONY 42M1 plasma display, in Bulgaria its price is the same as Panasonic 42PW7 and the SONY is much better to me.
    But I made direct comparison between SONY 42M1 and SONY 42MRX1 (720x1024) with LOTR 3 extended edition.
    I did not buy the 42M1. Now I am saving for 42MRX1 or similar model.
     
  6. Swa

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    Is the difference in resolution really hard to notice? This is very important to me. If the PQ of a plasma with a 852x480 resolution with non-HDTV material (PAL DVD) is less than a CRT TV or plasma with 1024x768, than I don't understand why people are buying a plasma with this resolution.
     
  7. Nick_UK

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    Because they're cheaper. The more pixels on the screen, the more expensive it is to produce, and the more sophisticated is the electronics required to drive it. It's all about price.

    I own a 1024 x 768 screen, and the other day I visited a friend who owns a lower res screen, and I spotted the difference straight away. No matter how good the scaler is, reducing the resolution to fit the screen is not a smart move in my opinion.
     
  8. Swa

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    They are a lot cheaper that's true. Because I don't want to buy a higher resolution plasma yet, I am considering the plasma 37pa50 or the normal TV 32pd50. A difficult decision, but reading your reaction I might be better of with a 32pd50?
     
  9. peezee

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    So yr question in essence is: for viewing regular SD PAL material only (720x576 resol. cable TV, PAL DVD's), is an SD plasma good enough, or shall I spend more ££'s and get a 1024x768 display for noticeably better PQ?

    First off, the original (from the studios) PAL source signal is 576i (interleaved), i.e. it only contains 288 lines per frame displayed at any one time. If we apply the usual 0.65 efficiency coefficient b/w interleave and progressive, the 576 interleaved signal is perceived by us as the equivalent of 576x0.65=374 progressive lines. While an SD plasma is capable of displaying 480 progressive lines (progressive meaning: that can be displayed all at once).

    Then, you have to consider the huge amount of compression that's applied to the original PAL source material before broadcasters (cable co. in yr case) transmit it to yr STB at home. So not only you start with a 576 interlaced (374 effective) signal but in addition it's heavily compressed, therefore losing visual information/details.

    This all means that 480 lines of pixels are indeed more than enough to accurately represent a 576i interleaved compressed PAL TV signal.

    In fact there are other *much* more important factors that play a key role in the image PQ, like contrast ratio, scaling/deinterlacing capabilities, colour reproduction accuracy, etc...

    DVD's are about the same, except that they're much less heavily compressed, therefore they deliver a better picture to begin with. This is where yr display (plasma or other) can deliver its best picture. Note that most films have a 2.35:1 A.R. therefore the # of active lines (non black bars) on yr display is not 576 but more like 434 lines. Once again I'm still to be proven, in theory or in practice, that a 1024x768 plasma screen delivers a better pic than a 853x480 screen *only* due to the difference in native resolution.

    One thing that plays in favor of 1024x768 displays is the "screen door effect", or SDE (it's the "grid" that surrounds pixels). If you're sitting far enough from the screen (>2,40m for me) you shouldn't be disturbed, otherwise you'll have to carefully check for it. On higher res displays the SDE is less visible, even from close distance.


    Conclusion: bar the SDE, you can practically discount resolution as a key factor for SD viewing, only *your eyes* can tell you which display is best, not the numbers... ;)


    P.S. This will all change whenever HD sources (HDTV, HD-DVD, ...) will become mainstream. But as you notice, we're still quite a long way off... :)
     
  10. Bengbeng

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    Indeed, a 4:3 aspect ratio Pal dvd has 576 lines vertical with full information. 1.85:1 and 2.35:1 has black bars in those 576.

    However, a 16:9 Palplus broadcast has coded information in the black bars which will bring the vertical res back to the original 576 lines, but the tele needs a Palplus decoder for that. I'm not familiar with a pdp screen that has one. (and BBC doesn't use Palplus as far as i know, here in Holland it's more common)

    But most important question, what is your viewing distance? If that is 4 x the image width then the human eye cannot resolve more than 484 pixels vertical (with a 16:9 ar), so problem solved. :)

    Watch this table:
    http://www.avsforum.com/avs-vb/attachment.php?s=&postid=5569005
     
  11. Nick_UK

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    I find it totally amazing that very few people would choose to look at their PC monitor at 640 x 480, but many are happy to spend hours telling us how it's quite OK to look at 852 x 480 resolution on a screen that's four times the size :suicide:
     
  12. Swa

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    Peezee thanks for your reply !!
    So for our current DVD's you do not need a 1024x768 resolution, the 853x480 is enough.

    But if the PAL source is interleaved, that will mean that first the first half of lines is displayed and then the second half. I don't believe that the second half can be displayed on the same place (lines) as the first half (the result will be a strange picture in my opinion), so you will still need 2x288 = 576 lines (correct me if I am wrong).

    Bengbeng: my viewing distance will be 3,5 x the image width.
     
  13. Orangelo

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    Swa, you are quite right in what you think. PAL (or NTSC) DVDs are interlaced in order to comply with the DVD Forum standard. That does not mean that the frames are split in two in the DVD itself, what happens is that they are coded or tagged, in order to distinguish the odd lines from the even.

    If you use a progressive DVD player, a progressive connection and a progressive Plasma display (which will most likely be the case), the DVD will transmit the full frame at once to the Plasma and yes, you will need a Plasma that can show 576 lines or more at once in order to see the full content.

    Even if you use an interlaced source, it is still very advisabe to have a display capable of showing 576 lines at once, because a progressive Plasma will deinterlace any interlaced signals that is being fed before showing anything onscreen. If the interlaced source is a tagged DVD, the DVD player will use the tags to transmit the even lines first and the odd lines afterwards. But the important part is that in the majority of the cases the Plasma will merge both fields (using the same tags) to reconstruct the original frame and show it all at once and, again, you will need 576 lines or more, if you want to see the full content.

    This does not mean that an XGA plasma will be better than a low-res model because many other factors intervene in picture quality. Without leaving the resolution department, it's much easier to downscale a signal than to upscale it, as the latter involves the creation of new information, and for that reason alone a 480p display may look sharper than an XGA one. That's why scalers are so appreciated by HD plasma users.

    BTW, I said earlier that you needed 1024x576 to view the full PAL content and that is only correct if the pixels are square, which is not the norm with Plasmas. The correct way of putting it is that you need a 16:9 720x576 display to see the full content in a PAL DVD.
     
  14. MAW

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    Bengbeng, Pal is 576 lines tall whether 16:9 or 4:3.
    SWA, what was said is that the amount of info in the interlaced image is about equivalent to 374 lines of progressive. I suppose it should be half, but it's never so bad prob due to persistence of vision, you can't see the interlacing. Yes, all 480 displays theoretically can't display all the info in a pal signal, the point is that this is not the place where most PQ is lost. That happens at the broadcaster, where they only send half of it anyway cos that's all the bandwidth they can afford. The other area of concern is internal processing. The more of it there is the worse it will be, and of course the quality of components varies hugely. This has a greater bearing than the resolution for sure. Panasonic SD screens used to be completely brilliant till they decided to cut the price in the time honoured fashion, ie leaving some bits out. The circuitry is still in the PHD display, which is one reason why the PHD looks so much better. Still doesn't make tha SD version a bad panel, for the money it's still streets ahead, but the PW4 showed almost no solarisation, that all started with the 5 series. That's the clearest example of the effects of processing I can think of.
     
  15. Bengbeng

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    First, the viewing distance/screen-width ratio is mostly smaller when you're behind a PC. The smaller this ratio the more need for a higher res because your eyes become more resolving. Besides this, you'll gain more space on your PC desktop when you set a higher res. (untill you reach a point where you cannot see things comfortable anymore)

    With HT beamers the need for a higher res is also there because in this case the vd/sw ratio is also very small (sometimes even smaller than 2.0). If you're watching a 42"PDP from let's say 12 feet then the ratio is about 4.0.
    With this ratio your eyes cannot resolve more then 484 pixels vertical, unless you have the eyes of a hawk or dog. :) Your Dobermann Pincher will love your HD purchase. :D
     

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