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Plasma Screen Geometry

Discussion in 'Plasma TVs' started by eddyad, Dec 30, 2004.

  1. eddyad

    eddyad
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    Are plasma screens free of all the geometry and colour alignment problems of CRT TVs?
    I'm thinking of things like pin-cushion distortion, bowing, linearity and so on.
    As they are digital I assumed they should be, apart from trivial adjustments like picture width and height.

    I spent more time than I care to admit with a Sony service menu and I wouldn't want that again. It's too scary - one slip and no TV :(
    Trouble is, now that I have a DVD machine with a JPEG viewer I'm tempted to try to iron out a few minor things.

    I'm not sure that a dealer would want to fiddle around while I got picky over his shoulder. Also, I'd probably prefer to buy online.

    I found some references to 'service menu' in this forum and it's worried me. I was hoping that at the prices of flat screens they would be delivered pretty near perfect for geometry, with all other stuff readily accessible to the user.
     
  2. Nick_UK

    Nick_UK
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    The geometry of plasma and LCD is perfect. There are usually no controls for the height/width available to the user, but there are some in "secret menus" which should be accessed and adjusted only if you are totally sure of what you are doing.
     
  3. LV426

    LV426
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    Height and width can often be adjusted via service menus. So it is possible (with incorrect adjustment) to get things too tall or too wide. I suspect that these sets are delivered with these values set just right - after all, it's much easier to do than with a CRT.

    Other than that, it's impossible for there to be any geometry issues, colour registration issues, magnetic interference, etc etc.
     
  4. blindlemon

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    ....if you consider 7% overscan on all 4 edges of the picture to be "just right", then maybe so :devil:

    Otherwise, you will have to mess with the service menus a little to see all of what's on a DVD etc.
     
  5. LV426

    LV426
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    5% is the accepted standard. All displays should do this.
     
  6. eddyad

    eddyad
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    Thanks for the replies. They've made me happier...

    I've found with my current CRT TV something similar to what overscan seems to be.
    When I view a JPEG image fom a CD-ROM using a DVD machine, I lose the edges of a 16:9 (1024x576) image all round - annoying when I've spent ages carefully editing and sizing the images.
    The solution is to make 16x9 JPEGs 960x540 pixels cental on a 1024x576 pixel background.

    So I'm losing 64 pixels horizontally which is 6.25% of 1024.
    If I mess with the Sony geometry to get all 1024x576 image in then normal 16x9 TV pics don't quite fill the screen.

    It seems as if I'd get the same effect from a Plasma and I wouldn't have to redo all my JPEGs. Or am I missing something?

    Incidentally, I've downloaded some Plasma instruction manuals and Sony seem to have some picture size adjustments.
     
  7. LV426

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    Don't think you're missing anything (except 5% all round:) ). The overscan is unlikely to be exactly the same - production tolerances - but it will probably be close enough.
     
  8. eddyad

    eddyad
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    Now I have another question and would appreciate comments:

    Is it advantageous to have JPEG sizes match a target Plasma screen resolution if possible? As I'm scanning slides, I can vary the resolution and the final image size to anything reasonable. The display would be via a DVD player RGB (composite is in the future) connection.

    As I don't have a Plasma screen yet I though of going for 1280x720 JPEG images.

    Thanks
     
  9. LV426

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    DVD player is going to output a standard television signal (by whichever connection). If it's PAL then it's 576 usable horizontal lines. So whatever it is, some rescaling of the original image is going to occur. If you really want to limit this then ???x576 is the "right" size. (or 480 for NTSC).
     
  10. eddyad

    eddyad
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    Thanks for that. I wanted to avoid losing potential quality on the TV because of a bad decision on the PC resolution which I have control over.
     

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