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Activity Forums Apple Final Cut Pro Image mask changes size when applied??

  • Image mask changes size when applied??

    Posted by Tim Vining on July 21, 2016 at 10:34 am

    I’ve been banging my head against this for two days: I have an animated object clip that I created a greyscale clip for to use as a mask image to give the clip translucent areas using the Image Mask. It works in terms of creating the translucent areas, but despite that the clips are exactly the same size, generated in exactly the same way, the greyscale clip blows up in size and doesn’t line up with the object clip, and there is no way I can see to control the size of the mask once it is applied, you can only adjust its offset. We did this frequently in FCP6, but I am stumped in FCPX. Am I missing something??

    Steve Crow replied 7 years, 2 months ago 3 Members · 4 Replies
  • 4 Replies
  • Bret Williams

    July 21, 2016 at 4:23 pm

    You’re using the image mask effect? That’s ok for just masking out some video, but it’s use as a precise matte channel for animation like you’re doing seems to be broken or limited. I think it’s screwy in the same way as drop zones.

    The way you want to do it is similar to FCP legacy. Add the matte layer above the animation layer (or is it vice versa?- can’t remember) and compound them together. Then open the compound and change the composite mode of the matte to stencil alpha I think.

    Play around with that, or someone else may post the specifics. I’m not at the system at the moment.

  • Tim Vining

    July 21, 2016 at 6:01 pm

    That did it–thanks! I put the greyscale above the image, and I used Stencil Luma Blend Mode, since I wanted to use the lights/darks for opacity. You are a life saver!

  • Bret Williams

    July 21, 2016 at 6:09 pm

    Oh, right, Luna not alpha. Glad that worked.

    You can also do it “non compounded” by choosing to do it “behind” but it limits other things so a compound is best as it now just functions as a clip with alpha.

  • Steve Crow

    February 24, 2019 at 7:17 pm

    Hey Tim – thanks for that – I was so confused why my mask image was resizing – your solution worked great!

    Steve Crow

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