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

[Øyvind Kolås <pippin gimp org>]

On Thu, Mar 29, 2012 at 4:12 PM,  <bootch nc rr com> wrote:
> 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.

There is no such op at the moment, but it does sound like something
that would be a useful building block for other things.

> 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.

The proper migration of GIMP to GEGL has ramped up significantly the
last month, in GIMP-2.10 the tile based drawable API will be marked as
deprecated and the official way for plug-ins to interact with the GIMP
core will be through GeglBuffers, for a very simple example see this
file:

http://git.gnome.org/browse/gimp/tree/plug-ins/common/goat-exercise.c?h=goat-invasion

/Øyvind K.
-- 
«The future is already here. It's just not very evenly distributed»
                                                 -- William Gibson