Filter greyedge
  Estimates scene illumination by grey edge assumption.
    slice threading supported
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
greyedge AVOptions:
  difford           <int>        ..FV..... set differentiation order (from 0 to 2) (default 1)
  minknorm          <int>        ..FV..... set Minkowski norm (from 0 to 20) (default 1)
  sigma             <double>     ..FV..... set sigma (from 0 to 1024) (default 1)

This filter has support for timeline through the 'enable' option.

