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  • Adobe After Effects Expressions

    expression using alpha

    Posted by Mike Sev on December 18, 2008 at 4:06 pm

    hey guys,

    I’m looking to drive an effect based on the alpha of another layer on a per pixel basis.

    So I want to pull the alpha from my matte layer using [3] and then apply that value to an effect on another layer. I can pull the alpha value from any ONE pixel right now and apply that value to a slider effect, but I’m trying to do this for every individual pixel so that they are all effected differently based on the alpha of the corresponding pixel on the matte layer.

    I know I can use the “alpha matte” function but that will only drive the opacity of another layer, I want to drive a different effect using that same data.

    Hope I explained that right… any help would be greatly appreciated.

    thank,
    mike.

    Trent Armstrong replied 17 years, 8 months ago 2 Members · 1 Reply
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