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  1. Member
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    Ok, so I'm experimenting with Avisynth, and I'm testing out the different plugins. I'm currently trying out the ColorMatrix plugin, and I'm having a little trouble. So the plugin is supposed to improve the quality, but I think it seems to make it worse. Here are some screenshots of the videos.

    Original mpg file:


    XviD without Color Matrix:


    XviD with Color Matrix:


    The Color Matrix seems to add too much yellow or something, and it just doesn't look right. Does everyone else agree that the quality is worse with the plugin?
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  2. Colormatrix isn't supposed to "improve the quality" of the video. It's supposed to fix the colors if the video is using the wrong colors to start with. Without knowing what colormatrix was used in the original MPEG file there 's no way of knowing which of your images is correct.

    An MPEG file may use either the rec.601 or rec.709 matrix. From your MPEG image there's no way of knowing whether the software you used to prepare the image used the right matrix.
    Last edited by jagabo; 5th Jun 2010 at 10:14.
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    Well, what I read somewhere is that most HD broadcasts are Rec.709. so I'm pretty sure that's what this is. What I was doing was allowing autogk to make avisynth scripts, and then testing them in VirtualDub to see how they worked. AutoGK automatically used the ColorMatrix filter and converted the matrix from 709 to 601, so why would AutoGK do this?
    Last edited by Mdoodm1000; 5th Jun 2010 at 10:26.
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  4. Originally Posted by Mdoodm1000 View Post
    Well, what I read somewhere is that most HD broadcasts are Rec.709. so I'm pretty sure that's what this is. What I was doing was allowing autogk to make avisynth scripts, and then testing them in VirtualDub to see how they worked. AutoGK automatically used the ColorMatrix filter and converted the matrix from 709 to 601, so why would AutoGK do this?
    Because that's the right thing to do to a rec.709 source when converting to Divx/Xvid. Divx and Xvid use rec.601.
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    Oh okay thanks for the info. I'm just wondering why the video looks better if I disable the Color Matrix. I read that if the video looks yellowish, then the wrong Color Matrix is being used.
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  6. Originally Posted by Mdoodm1000 View Post
    I read that if the video looks yellowish, then the wrong Color Matrix is being used.
    Yellowish compared to what? How do you know the image in VLC is correct? VLC always uses a rec.601 matrix to decode MPEG2 video. If your source is rec.709 VLC is displaying it incorrectly.

    Open your MPEG source with DG Index, what does it say about the colorimetry? If there is a * by it that means the colorimetry isn't specified in the MPEG data and DgIndex is assuming that colorimetry. In the absence of flags it will assume rec.601 for SD, rec.709 for HD.
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    The third screenshot looks yellowish compared to the second one.
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  8. Originally Posted by Mdoodm1000 View Post
    The third screenshot looks yellowish compared to the second one.
    Yes, but how do you know the yellowish one isn't right? Just because one image is yellowish compared to another doesn't mean the yellowish one is wrong. The quote about yellowish colors means yellowish compared to a correctly decoded image.
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    It's funny how we've all become so picky on slight color changes after 50+ years of absolutely
    crappy color fidelity (NTSC SD) - You'd have thought we'd not be so sensitive to it after that ?
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