[png-mng-misc] Fw: PNG filters

[chportko <chp...@ya...>]

[ non-member submission, don't forget to CC
               - Moderator ]


Dear  Thomas Boutell, Mark Adler and employees of PNG Development Group!

I am sending on at your consideration a filter created by myself with the
purpose of including the latter into standard PNG: 

Function AverageLaneFilter (Left, Upper, UpperLeft, UpperRight)
 begin
  return Left+(UpperRight+2*Upper-3*UpperLeft)/4
 end

Here Left is the value of similar components of the previous point,
UpperLeft, Upper, UpperRights  are the value of similar components
according to the left, central and right points in the previous line
correlated with the filtered.

More detailed _ in the file of FiltrPng.doc