• Adobe After Effects Expressions

  Using pixel data from a target layer to drive scale.

  Posted by Justin Maloney on November 20, 2018 at 4:23 pm

  Is there a way to link a value (like scale) to pixel data from a target layer, say, underneath the former’s anchor-pointw?

  I’m trying to use a ramp or blur of a solid layer sweeping across the frame to drive the scale of several smaller layers.

  Here is the expression I’m using now.
  /////
  sampleSize = [10,10];
  target = thisComp.layer(“DRIVER”);
  samplePos = [target.width,target.height]/2;
  rgb = target.sampleImage(samplePos, sampleSize, true, time);
  hsl = rgbToHsl(rgb);
  [hsl[2]*100,hsl[2]*100]
  /////

  “DRIVER” is the ramped/blurred solid.
  This expression sorta works but it doesn’t look very good. I actually ripped this from a thread on using pixel data to drive opacity.

  Justin Maloney replied 7 years, 9 months ago 2 Members · 2 Replies
• 2 Replies

• 

  Dan Ebberts

  November 20, 2018 at 4:42 pm

  Try it this way:

  sampleSize = [10,10];
  target = thisComp.layer(“DRIVER”);
  samplePos = target.fromComp(toComp(anchorPoint));
  rgb = target.sampleImage(samplePos, sampleSize, true, time);
  hsl = rgbToHsl(rgb);
  [hsl[2]*100,hsl[2]*100]

  Dan
• 

  Justin Maloney

  November 20, 2018 at 5:29 pm

  Awesome! Thanks again Dan!

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