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Poor Interpolation by LCD TV's

Discussion in 'LCD & LED LCD TVs' started by satwar, Jun 13, 2005.

  1. satwar

    satwar
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    I've been reading that HD LCD TVs have relatively poor interpolation abilities when fed a regular TV signal compared to CRT TVs. Can someone explain why?
     
  2. Digitised

    Digitised
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    Its absolutley true that CRTS hold a better picture than a HD display when using standard definition pictures.
    But at the same time it doesnt really matter because in 12 months you will be able to watch all your TV, DVDs, and play your games consoles in a HD supported format.


    Answer to your question....

    The reason LCDs suffer is because unlike CRT screens, LCDs have a fixed resolution.
    CRTs have NO fixed resolution because the image is a scan, the image is shot at the screen line by line as it is told to do (within limits of course).

    If you display a 480x640 image on both a CRT and an LCD, the CRT will produce that image at that set resoltion 1:1.
    Whereas an lcd with a fixed display of 1280x1024 will have to comprimise by dividing 1280 into 480, and 1024 into 640.

    As you can tell these numbers do not divide equally, and therefore the pixels cannot be represented accurately. The resulting image will look very blurry and suffer possibly from ghosting and other motion problems. On top of this colours will also be merged where 4 pixels are all fighting to represent their own individual colour.

    The LCD panel would compare favourably if the image was 480x640 being displayed on a panel of 960x1280 (this is simply doubling up on the original image). In this instance 4 pixels would make up every 1 pixel of the original image.



    Although we are still using standard definition as standard there are some excellent LCD screens that use digital processing to filter and add extra detail into the EXCESS pixels that their units posess.
    Pixel plus 2, WEGA and others all take a Stanard Def picture and display it over their panels and add extra detail by 'guessing' what should be displayed inbetween.

    This technology greatly enhances Standard Def, and brings it fairly close to an HD like image.
     
  3. Phil from 62

    Phil from 62
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    :confused: Following on from the original question concerning poor interpolation abilities with regular TV signals...does the picture quality on LCD increase/change at all dependant on the signal source....
    i.e. Analouge Aerial, Digital Aerial, through a Freeview receiver, via Satellite or via Cable etc etc or is it more to do with the broadcast rather than the receiving???
     
  4. David Mackenzie

    David Mackenzie
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    Digitised, great explanation. I think that should go in the forum FAQ.
     
  5. satwar

    satwar
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    Makes sense, seems so simple now that I wonder why I even asked.

    Great resonse Digitized, in easy to understand terms.

    Thank you very much.
     
  6. jimsan

    jimsan
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    Congrats DIGITIZED! Top post!

    The answer to the above quote is YES! Most definitely! This is what LCD's are all about. The better the feed quality the better the picture. Re-read Digi's post and you'll understand why.

    Jimmy
     

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