Dealing with over-sharpened image of Sony camcorders

Discussion in 'Amateur Video Production' started by carpathian81, Dec 20, 2005.

  1. carpathian81

    carpathian81 Guest

    Consumer Sony mini-dv camcorders usually deliver severely
    over-sharpened image. I assume this imrpoves the picture when watched
    on TV, but looks quite harsh on a good computer screen. Edges develop
    clearly visible halos that can span several pixels. This is due to the
    internal sharpening algorithm of the camcorder, which normally cannot
    be skipped.

    Smoothing/blurring is the obvious way out, but it took a while for me
    to select the right filter and the right parameters (I work in
    Virtualdub). The camcorder sharpens every field separately - this is
    why over-sharpening artifacts are far more pronounced in the vertical
    direction. So, the first thing to do is to unfold the fields side by
    side (an option of the Deinterlace filter) and apply the filtering to
    each field separately. The corresponding folding filter (another option
    of the same Deinterlace filter) shold follow; the smoothing filter will
    reside between the two.

    The smoother of my choice was General Convolution 3d, which 5x5
    matrices. This is better than the internal 3x3 convolution, but slower.
    To define ordirary Gaussian Blurring, one should enter the following
    values into the third matrix:

    1 4 7 4 1
    4 16 26 16 4
    7 26 41 26 7
    4 16 26 16 4
    1 4 7 4 1

    The central value (41) can be changed to define the "strength" of the
    filter; the bigger the number, the weaker the smoothing is. I found
    that the value of 120 works fine.

    When shooting in the internal 16x9 mode, the horizontal sharpening
    artifacts are even less apparent due to the horizontal squeezing of the
    image. In this case, the matrix may be modified to only perform 1-d
    vertical blurring:

    0 0 7 0 0
    0 0 26 0 0
    0 0 41 0 0
    0 0 26 0 0
    0 0 7 0 0

    After the processing, the image will appear softer and most of the
    halos will be gone; however, the worst artifacts cannot be removed
    carpathian81, Dec 20, 2005
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  2. carpathian81

    Doc Guest

    I've never noticed this on my Digital 8. Probably another good reason to
    stay in that format
    Doc, Dec 30, 2005
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