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

[<bootch nc rr com>]

---- "Øyvind Kolås" <pippin gimp org> wrote: 
> 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.

!? Nevermind: I think the gegl:scale with filter=cubic might be the same as reduce.   I will study more.

> > 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

OK.  It is not clear to me that the new API using GeglBuffers will let Python plugins use GEGL, 
only C-language plugins, unless there are more changes to, for example, the GIMP PDB or to Pygimp.
But I understand it is not high priority, since few GIMP plugin developers, using Python and Scheme, need 
direct access to GEGL?  
I suppose the guiding principle is that fundamental filter operations should be GEGL plugins written in C.  
But why should non-fundamental Python GIMP plugins need to go through the PDB to get to GEGL?  
I suppose the architecture of GIMP plugins is of no concern to GEGL, and I am not an expert.

Anyway, I will defer until after 2.10.

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