[Gegl-developer] gaussian reduce operator, and GIMPGEGL operator

[<bootch nc rr com>]

This message has two subjects.

1. Is there a gaussian reduce operation in GEGL?  Refer to the paper by Burt and Adelson, 1983, where it is 
called REDUCE and apparently claims that it is faster than operation gaussian blur followed by down-sample 
(scale by 1/2).  Used in the production of a gaussian pyramid.  It seems to me to be a fundamental operation 
and should be in GEGL.  A search shows that the operation mantiuk06 for GSOC might have generated gaussian 
pyramids but AFAIK did not expose reduce() as a operation.  There is also a corresponding inverse operation 
EXPAND, which is useful in generating a Laplacian pyramid.  I have a use for a gaussian pyramid and might 
consider implementing gaussian reduce for GEGL (instead of the naive approach of using gaussian blur followed 
by scale.)  The gaussian and laplacian pyramids are used in texture synthesis and image compression.

2. A few weeks ago I posted to GIMP-dev list about https://github.com/bootchk/pluginGEGLpluginGIMP a GEGL 
operation that lets you used GEGL in GIMP plugins written in Python and using Pygegl binding.  Its not in the 
form of a proper patch to GEGL but I would make a patch if I thought it would help anyone to evaluate whether 
it should be part of GEGL.