How to deal with OVERSCAN ?!

Discussion in 'Displays' started by Samuel_Fred, Feb 2, 2004.

  1. Samuel_Fred

    Samuel_Fred Stunt Coordinator

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    I'm been really bummed out lately because I can't seem to find a decent way to fix my TV's overscan. It's a Philips 30" HDTV.

    Are there TVs out there that have no or next to no overscan?

    Or are there TV's that let you easily (without hurting image quality) to adjust overscan?

    I know there are a couple DVD players that do this: which are the best? (I have a Jaton, but it's being service for other problems...)

    What's the best way to deal with this most annoying -- and epidemic -- problem??

    Philips and their authorized repair service have been giving me the runaround -- technically it's not a defect (true), so it's questionable whether adjusting the overscan would be covered by warranty. Also, the repair technician claims there's the danger that adjusting the overscan (down to 1% or less, as I'd like) might interfere with the image quality in some other way. Is this true? Also, why is there overscan in the first place?
     
  2. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    Gregg Loewen
    Hi

    do a search for overscan and look through the frequently asked questions. Your set will do about 4% nicely, anything more than that and you will have a lot of problems with geometry, convergence etc,

    Regards

    Gregg
     
  3. Lew Crippen

    Lew Crippen Executive Producer

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    Most direct-view have overscan, it is just question of how much Paying for an ISF calibration and getting the overscan down to 3%–5% is probably your best bet.

    1% (or less) overscan will most probably cause problems in properly reproducing the picture (you will likely get quite a bit of distortion). This is because 16:9, flat screens cause extremely difficult problems for the scan of the electron guns. Many manufacturers hide this problem to a degree with some overscan.

    It is likely that your set’s electronics won’t be able to accurately reproduce the edges of your picture at 0%–1% overscan. 3%–5% is really not to bad in practice, as you get no black bars on 1:85 movies and just a little cropping on the vertical edges of the picture. TV shows are filmed assuming some overscan, so what little you would lose on the picture edges is already considered (for the most part) not that important by those who composed the TV shots.

    Plasma and LCD displays don’t have geometry problems as the pixels are fixed, so there is no scan by an electron gun with which to contend.
     
  4. Lew Crippen

    Lew Crippen Executive Producer

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    Oops, sorry Gregg you posted while I was writing.
     
  5. Samuel_Fred

    Samuel_Fred Stunt Coordinator

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    So Plasma and LCD TVs don't have ANY overscan?
     
  6. Lew Crippen

    Lew Crippen Executive Producer

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    They don't have any geometry problems.

    In theory the overscan on these devices could approach zero, but I have no familiarity with the practical application.
     

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