Red/blue lines and dots in picture

Discussion in 'Beginners, General Questions' started by Roger_R, Nov 9, 2003.

  1. Roger_R

    Roger_R Second Unit

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    Hi.

    Sometimes when I watch DVDs, I notice red-blue "lines" in the picture where white meets black. For example a tree with black branches with a white sky as background. I was wondering if any of you know what's causing this and if I can remove it? I have a Denon DVD-3800.

    I notice it mostly on TV-productions, such as Deep Space Nine and X-files.
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    What kind of TV do you have? If you have an RPTV, it sounds like the convergence needs some touch up.
     
  3. Roger_R

    Roger_R Second Unit

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    It's a Grundig 32" widescreen TV. Ordinary CRT with a flat front.
    I can also see it when I play back the DVDs on my computer. I just thought that it was because the software DVD-players for computers do a worse job of decoding the DVD and that normal DVD-players should be able to remove it..
     
  4. Roger_R

    Roger_R Second Unit

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    I've taken a couple of images, showing what I'm talking about. They were taken with WinDVD 5, not my DVD-player.

    s-island.mixnmojo.com/DS9S2D1-1.jpg Here you can see it on the "arm" of the station that's closest to the camera.

    s-island.mixnmojo.com/XFILES5-1.jpg Here you can see it on top of Skinner's head. It's not as apparent though.
     
  5. Allan Jayne

    Allan Jayne Cinematographer

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    The source material may have been composite video at some point in its lifetime. You could be seeing artifacts from comb filtering needed and done in the production studio in order to master a DVD from the material.

    Although many TV productions are shot initially on film, many are not and the submaster used for almost all purposes is composite video.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  6. Roger_R

    Roger_R Second Unit

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    So it's because of crappy mastertapes? Hmm...funny that DVD-players don't have a built-in filter to fix it.
     
  7. Allan Jayne

    Allan Jayne Cinematographer

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    Most problems, in the source material, master tapes, or production process cannot be corrected at the receiving or playback end. Some problems can be hidden at the expense of softening the entire picture or doing some other work around that may compromise the playback of good source material.

    Comb filtering artifacts are cumulative. Trying to undo comb filtering problems makes things worse, not better.
     

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