Difference Mattes

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Intro

  • Not to be confused with colour difference keyer.
  • This is a matte based upon the difference between two images.
  • Because of noise (grain etc.), and tiny movements on a camera head or background using these as a precise extaction mattes rarely works.
  • They have other uses like creating rough mattes and checking quality (before and after).

Script Example

Image

Maths

[A-B]-[B-A] RGB difference matte =[abs[R1-R2]]+(abs[G1-G2]]+[abs[B1-B2]]
(from "Digital compositing for Film & Video" by Steve Wright 2002): single channel difference matte abs stands for absolute values

Bump Matte

  • Creates a matte that shows the difference of the region immediately adjacent to each other.
  • Similar to a difference matte, but made from by subtracting the blurred version of a plate from its self. By colour correcting the blurred version with a ADD or SUB you can increase or decrease the bump.

External Links

External Links


Created by ome. Last Modification: Friday 02 of January, 2009 11:44:56 GMT by ome.