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  • choking a matte layer

  • Elin grome

    March 18, 2010 at 5:59 pm

    Hi guys,

    I have a black and white layer which i am using as a luma matte…

    the problem is that there’s a bit of the background showing through so i would like to choke the matte a little bit; ie eat into the white area a little with 2-3 black pixels…

    but because this is a luma matte the simple choke doesnt work – it only works on alpha areas…

    can anyone help? ūüôĀ

    thanks in advance

    Elin

    It’s all the those pesky details :p

  • Samuel Hall

    March 18, 2010 at 6:13 pm

    I don’t have AE in front of me right at this moment so forgive me if this doesn’t work:

    You could try pre-composing the layer and it’s luma matte and apply a matte choke to the new pre-comped layer.

    Samuel Hall
    DP/Editor/VFX/Music
    http://www.vimeo.com/samhall

  • Darby Edelen

    March 19, 2010 at 8:33 am

    You can apply a Channels > Set Matte effect to the black/white matte and set it to use it’s own luminance as a matte, then apply the Matte > Simple Choker effect and use this layer as an alpha matte.

    The alternative is using Channels > Minimax applied to the black/white matte set to a Minimum operation with a radius of 1 or 2. However, if there are subtle details in the black/white matte then this can end up chunkifying those.

    These two different methods will have two different results, so try ’em both and see which works better.

    Darby Edelen

  • Elin grome

    March 19, 2010 at 11:08 am

    Darby – your first solution worked fine – but thanks guys, all interesting techniques…

    Elin

    It’s all the those pesky details :p

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