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SD panels and HD material, can you tell it's HD?

Discussion in 'Plasma TVs' started by zAndy1, Jun 1, 2004.

  1. zAndy1

    zAndy1
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    Hi,
    Can you tell the difference if you send a hidef signal e.g. 720p or 1080i to an SD panel like the Panny 6 series (852 x 480). It would have to do some serious scaling down and you'd think the extra resolution/detail would just be lost but is that the case? Don't suppose anyone has hooked up e.g. a Yamakawa and sent the display a 720p signal to see if it looks better than 480p?

    Cheers,
    Andy.
     
  2. cybersoga

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    HD material is usually better quality than DVD even if it is downscaled, but there will be less difference if the respective DVD is good anyway (an interesting comparison would be spiderman superbit vs spiderman HD on a SD screen and HD scaler)
     
  3. loonatic

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    Well I can't really see it being a very good combination myself...but Buns would be the chap to ask as he has an SD panel with a lovelly new LumagenHDP with SDI Sky+ and DVD and he thinks it's great.

    But if you take a true HD source, not SD upscaled, then that would be the real test as in theory you would be loosing so much of the source material in the downscaling process. It would probably result in a cleaner, less noisy image I would guess.

    But tru HD on a HD panel is the way to go. Trouble is once you've seen it you wouldn't want to watch anything else.

    Cheers, Lee
     
  4. buns

    buns
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    Hi guys,

    As Lee says, I have the SD panel and am feeding it a 'HD' signal from a lumagen processor. As said, this isnt true HD so it isnt easy to answer your question.

    Now, things are even further complicated by your method of connection. I am connected by analogue. I prefer 720p to 480p, it looks less noisy and colors are more solid. Were I looling at an HD source (true HD), the image can only look better (of course assuming that the HD source is actually producing a better image than the SD source- not necessaily the case I suspect).

    Bug with a digital link i myself wonder how things are. With digital the best way to send a signal to the display is a 1:1 pixel map. Of this there is no debate. So.... with a digital link, would an HD source look better downscaled to SD BEFORE it entered the display? :D an interesting question that perhaps someone here can answer...

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    ps. maybe i confuse about HD and SD source picture qualities. What I meant is whether a new HD technology can actually produce a superior quality picture to my mature and highly modified SD source.... sure the HD has higher resolution, but a ferrari engine in a ford fiesta will have alot of subaru's smiling at it.....
     
  5. SimonO

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    buns, have you been drinking..? :beer: ;)
     
  6. cybersoga

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    Here's the matrix DVD vs the matrix HDTV downsized to the same resolution as the dvd using bicubic fitering in photoshop. spot the difference!

    Bjoern Roy also makes the same point with Lord of the Rings

    I don't think the firmware of the new lumagens can do HD scaling _yet_
     
  7. buns

    buns
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    Sorry guys, It is actually quite tricky to say what I was trying to say without it sounding an absolute mess! Id really have to sit down and think about it! Hopefully you got the jist of it!

    The 'yet' is very important on the lumagen, I dont know if it can do it yet (i have no way of trying) but it WILL be able to.

    The matrix shots there surprise me, I didnt think the difference would be that noticeable..... i'll have to look again when I have a decent monitor to see if I can pick anything else out

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  8. Cummo

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    Hi zAndy1,
    I spent some time in a local HiFi store here in Canberra last weekend comparing different displays running the HD test loop. The Canberra version of the loop is at the low end of the HD bitrate scale but is certainly better than what is provided in our SD transmissions. The signal is 1080i.
    The store has placed a Panasonic 37pa20 plasma in the centre of several fine pitch crt's All were running the loop so, it was easy to do a side by side comparison as to lost detail of the PAL signal on the 480 line plasma. I've spent the last 8 years doing detailed design work on large Sony monitors, so believe I have a reasonable eye for detail.
    My viewing was done at 2 metres, so some 'screen door' effect was noticeable on the plasma. The water mark on the plasma was in the same location as the crt's, so obviously the PAL image was not being cropped in the down conversion to 480 lines. In the 20 minutes of checking the finest of details, the only differences i could find was in a scene where the writing on the side of a train rounding a bend looked slightly clearer on the Sony fine pitch than it did on the plasma. In another scene where the camera pans quickly over tree tops, the detail actually looked better on the plasma. As you would expect, the colours on the Sony looked more vivid but the plasma had natural colour with a more stable picture
    Theoreticians on our local forum continually bag the 480 line plasma for its lost definition but as I say forget the thoery and do the practical test with a side by side comparison.
     
  9. cybersoga

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    I doubt that the downscaling built into plasmas is as good as photoshop, so there's not much point in feeding a plasma anything other than it's native resolution. An external scaler capable of scaling HD using advanced filtering algorithms has potential to squeeze more PQ out of a SD plasma whether it's being fed SD or HD.
     
  10. NeilMcRae

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    Actually it makes a huge difference. Running Steel Batallion LOC in 720p into my SD panel looks much better to my eyes than at 480p.

    Neil.
     
  11. buns

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    Neil is on the money to my eyes too..... 720p via analogue looks way better than native.

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  12. cybersoga

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    720p from what may I ask? If it's an HD source i'm not surprised the PQ is better. If on the other hand it's a dvd player outputting 720p then i'm surprised there would be much difference as the dvd player will be upscaling 480i to 720p then the display will be downscaling 720p to the native resolution. Downscaling will always produce a better picture than upscaling no matter how simple the algorithm used to do it.

    If it's a game console as in Neils case and 720p looks better than 480p then the display is still downscaling 720p to it's native resolution and this will look better because the game is being rendered in a higher resolution, even though it's being downscaled, among other things it's anti-aliasing the whole picture when it's being downscaled.

    This is similar to the reason that when they make a digital intermediate of a film for editing, sometimes they scan at 4k resolution (telecine) and then downscale to 2k for editing, this looks better than scanning at 2k as there will be less noise (grain) in the picture, but still isn't as good as scanning and editing the film at 4k (or indeed scanning at 6k/8k and editing at 4k), but of course 4k editing costs more, and takes up more memory which may mean they have to work on a smaller part of the film.
     
  13. jmack

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    i use the iscan hd to upscale sky/pal to 720p then i guess my sd panel downscales it. but its far the best picture i have had on there.
     
  14. buns

    buns
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    I deinterlace and scale 480i (or 576i) from an sdi dvd player or sdi sky+ box with a lumagen HDP. So I am upscaling then letting the panel downscale. If you look around the various video processor forums globally, there are scatterings of reasons for why analogue will be better at resolution above native even though the panel thus has to downscale. The best reason I can give is that an analogue connection will soften an image, at higher res you are doing the same softening but effectively on more data, hence the softening is less visible. Fair you may argue that this works with an HD source but shouldnt apply to an upscaled signal, but it is probably fair to suggest that (to an approximation) the upscaling gives more than the downscaling loses. I know this isnt strictly the case, but I do not know the technical side well enough to give a technical explanation.

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  15. cybersoga

    cybersoga
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    I know what your saying, by upscaling then downscaling it can overcome any loss due to analogue convertions, cables etc.
     
  16. buns

    buns
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    Yes, though im sure the reality is somewhat more complex. Of course the same arguement is absolutely not true with dvi or hdmi

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  17. zAndy1

    zAndy1
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    Thanks for the replies so far folks, made for quite an interesting thread! Got my TH37PE30 now but it won't accept anything more than PAL progressive (i.e. no 720p) so can't test this out anyway, not bothered cos I'll use my Z2 for all the high def stuff!

    Cheers,
    Andy.
     
  18. buns

    buns
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    are you serious? Are you sure that isnt simply on one form of input, i could have sworn there was a vga input and a dvi option, all of which should accept higher resolutions....

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  19. zAndy1

    zAndy1
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    Nope, pretty sure the Viera models don't accept 720p or 1080i. They're not listed in the specs in the manual. If anyone discovers otherwise I'd love to hear it! To be honest I'm not really bothered, I bought it as a TV and for the odd DVD, films are watched on the Sanyo Z2 so the lack of 720p on the plasma isn't really an issue.

    Andy
     
  20. buns

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    Im still surprised though.... alot of people will use a display like this for full fim watching

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  21. zAndy1

    zAndy1
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    Yeah, I don't know why it can't do 720p I thought it was the same panel as the 42PW6.

    Andy
     
  22. Jasonjo

    Jasonjo
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    I remember from avsforum that a lot of US guys buy the commercial version of the screen (PWD) as the US consumer version cannot do 720p, whereas the commercial one can. Maybe it is the same over here???

    JJ
     
  23. Jasonjo

    Jasonjo
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    buns,

    I took your advice and tried 720p with my iScan HD, and after quite a bit of fiddling, I do actually think it is better that my previous 852x480 1:1 setting. I obviously didn't spend enough time trying this setting last time :(

    Dont' really understand why, but hey, it's a better picture :smashin:

    Thanks for the tip!!! :)

    JJ
     
  24. buns

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    Not a problem JJ, it really is quite visibly different, I was expecting it to be small and something id probably not notice! You could of course consider sending it something even higher, the theroy is that you should send the highest analogue resolution the display can accept. I havent had time or inclination to do that just yet....

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  25. jmack

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    cant go higher on mine, 1080i is very shakey and 1080p gives a darker screen with streaky running though picture. maybe over component it will work.

    my manual says 1125i but there is no option for this in the iscan settings.

    720p is the best picture so far, its amasing how much differance in picture quality up from 480p and even 1.1 mapped
     
  26. rscott4563

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    On my Panny the best picture I got was with 1152p, from a dvd source there was a noticeable improvement over 720p and 768p.

    Ryan
     
  27. buns

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    I wouldnt try 1080i...... you really dont want to have to worry about the interlacing artefacts.... as Ryan shows, it is probably a case of trial and error to find one which you can accept (of course his is the 50 inch so a bit different).

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  28. Jasonjo

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    Cheers chaps...I will try 1080p, but it looks like 720p it is then!! :smashin:

    Since getting my Panny and HD, I wanna watch TV & DVD's ALL the time now...I love this thing called "Home Cinema" :) :D

    JJ
     
  29. jmack

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    jasonjo, let me know if 1080p works on yours,

    are you using vga or rgbhv 5 cable thingy?
     
  30. Jasonjo

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    Ok, will do ;)

    I am using RGBHV via the 2 slot card
     

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