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After-image or "screen burn" query

Discussion in 'Plasma TVs' started by MrNPG, Apr 20, 2005.

  1. MrNPG

    MrNPG
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    Hi folks,

    Reading the manual for my new Panasonic TH42PE50B and something is puzzling me.

    In the set up menu, there is an option to "highlight" the side panels when viewing 4:3 or 14:9 images, in order to prevent any possible "after-image" or "screen burn".

    I can understand why they have this and seeing as I NEVER use 4:3 or 14:9 mode, it shouldn't be a concern.

    However, obviously when you watch a 2.35:1 aspect ratio DVD, you still have black borders at the top and bottom of the screen. So, if I watch a lot of 2.35:1 movies, should I be concerned about possible screen burn???? I cannot see what the difference is between having black borders down the left and right of the screen (4:3 & 14:9 modes) and black borders at the top and bottom of the screen (with 2.35:1 movies). Surely if there is the "threat" of screen burn with the borders down the sides, wouldn't there be a similar "threat" with the top & bottom borders??
     
  2. Mep

    Mep
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    it could be an issue if you watched loads during the early hours without switching...but you can't do the brightness thing with the top and bottom bars as they are part of the dvd output...where as the side bars are 'unused' screen space and can therefore be changed
     
  3. Enquirer

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    Oil rich countries that have small armies have to worry about there borders :D Not Plasma owners that use there plasma sensibly.
     
  4. Mep

    Mep
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    :rotfl: very good Mr. Enquirer
     
  5. LV426

    LV426
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    The risk is the same. However, in the case of 4x3 material, it is the TV that puts the borders there, so they can be any colour the TV wants them to be. So the manufacturer can give you a neutral grey option.

    Whereas, with wider-than-widescreen DVDs, the black borders top and bottom are part of the video signal coming off the DVD, put there when it was mastered. And so there's nothing the TV manufacturere can do about it.
     
  6. MrNPG

    MrNPG
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    Cheers guys, as I thought. So if the "risk" is the same, anyone know just HOW much of a risk there is of damaging the screen whilst watching 2.35:1 movies?? If i was to watch a couple every day, am I likely to be risking damage or would you have to watch them ALL day long in order to cause any damage????
     
  7. Mep

    Mep
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    I think that's what I tried to say :)
     
  8. Mep

    Mep
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    a couple a day is going to be fine, though this is based on my experience with the pw7 and not your screen. If you go for a cup of tea or whatever half way through the film you can always switch to a seperate input for a while as well.
     
  9. bishman

    bishman
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    I understand what you are saying, but it's still not impossible, anything can be done to the picture when the display processes it before it is displayed. For example, most sets have an onscreen display that appears over the image, so surely some similar technology could be used to display a different colour in the borders?

    Not saying it's easy, just saying that because the image comes from the disk, it doesn't make it impossible. Is the image displayed exactly the one that comes from the disk, or does the display do some kind of digital processing/scaling etc? If there is digital processing going on, then it should be easy to incorporate some kind of facility to colour a border top and bottom.
     
  10. LV426

    LV426
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    No, nothing is impossible. However, what a TV set would have to do is detect which part of the video signal is black and replace it with something else.

    Now, if it so happens that there is a real scene in a film (say) where the actual FILM has a fairly straight plain black part to it (say, along the top in a night scene), how would the TV set know this as different from a black bar, and handle it differently?

    The point is, there is no difference whatever in the video signal in these two cases, so there's nothing "simple and technical" a TV could do. It would have to have some very clever real-time pattern recognition.

    So, perhaps not impossible. But, I suspect, far from simple either.

    To get back to the point, how much viewing causes damage - there isn't any definite answer. Too many factors, including

    - the relative brightness of the film itself
    - brightness and contrast settings on the screen
    - longevity of the phosphors

    etc.
     

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