• Adobe After Effects

  How to animate transparency along a gradient.

  Posted by Dave Sia on August 12, 2015 at 10:05 am

  Hello gurus.

  I have a project, I need to animate the transparency of a layer using a rendered grey scale image.
  So I need to have the “lighter greys” transparent and then crawling to the “darker greys” finally only the “blacks” will be transparent. better if i can control this grey selection sliding effect.
  Its kind of like animated clamp on a grey scale image.
  I am not sure if I described it correctly.

  Thanks in advance

  Dave

  Kalleheikki Kannisto replied 11 years ago 2 Members · 3 Replies
• 3 Replies

• 

  Kalleheikki Kannisto

  August 12, 2015 at 12:35 pm

  Put the grayscale image above the layer you want to apply the transparency to, then set the track matte of the bottom layer (of these two) to luma matte.

  If you want to be able to modify the transparency values, you can add (for example) a Levels adjustment to the grayscale layer.
• 

  Dave Sia

  August 13, 2015 at 2:28 am

  Thanks Kalle for the fast response.
  I also need to animate the transparency in a rather controlled way.
  Example: I need to have the greys RGB 160 to 165 to be visible (to make the bottom layer transparent) then it crawls to 165-170 then 180-185, increasing or decreasing in value -but with a constant clamp maybe 5 to 10 range.
  I need the visibility (narrow section)to slide/animate along the grey scale image provided.
  Similar to gradient wipe but only a narrow middle section to be visible.
  Thanks.

  Dave
• 

  Kalleheikki Kannisto

  August 13, 2015 at 7:38 am

  There may be an easier solution, but the first that comes to mind:

  Make a copy of your transparency mask and use animated Levels on one of the layers to set the bottom cutoff and on the other one to set the top cutoff, then invert the top and compose with Minimum blend mode. You’ll have to precompose the two layers together to get it to work as a Track Matte.

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