• Adobe After Effects Expressions

  Anyone had success using Steven Wright’s keying equation?

  Posted by Peter O’connell on May 4, 2006 at 4:18 am

  Hi I am reading a book called ‘Digital Compositing for Film and Video’ by Steven Wright. He has an equation used to create a matte and I am not sure how to plug it into AE. The equation is like this:
  Gray Value = square root [[R1+R2]squared + [G1+G2]squared + [B1+B2]squared]
  where [R1,G1,B1] is the normalized center of the colour you are trying to key out, and [R2,G2,B2] is every pixel in the image.
  How could I try this, I’m not sure where to begin, calculations? Arithmetic? and expression in Channel mixer?

  Stumped
  Pete

  Thursday; May 4, 2006
  12:17 AM

  barxseven.com

  Peter O’connell replied 20 years ago 1 Member · 0 Replies
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