Hi,

I've been working on re-animating the old User Filter plug-in by Jens Restemeier lately and it is now in a state where it begins to be usable.

You an find things at http://gimpuserfilter.sf.net/

I'm not announcing this to the general public yet, since I haven't made a release version yet (some things still need to be done, like a couple of command-line utilities and basic documentation of the functionality).

You're welcome to fetch the CVS though and haunt me with criticism ;-)

Torsten

Hi,

Could you perhaps say a little more? After 5 years of GIMP experience, I've never heard of this filter or have any idea what it does, and your page doesn't yet help.

Ok. So a short explanation for the younger folks... ,-)

The User Filter plug-in was a work-alike to the Filter Factory (I'll write FF now for this) of Adobe's Photoshop (PS from now on). It was able to load filter descriptions for this tool in different text file formats (.afs is a FF source, .txt a source from a 3rd-party tool and .ffl a filter conllection). FF also "compiled" these filters into stand-alone .8bf plug-ins for PS (which could be used using Tor Lillquist's pspi plug-in, by the way) which also could be used with User Filter.

The general idea behind the whole thing is to provide a means to be able to write filters without the need of going through the whole process of studying the SDK (Glib, Gtk+, libgimp in our case), compiling, and installing. Instead, the plug-in offers an editor with which filters can be implemented by writing a formula for each color channel that manipulates the pixel data of the image.

It is possible to implement almost any kind of filter with this tool - alas, since the code is interpreted byte-code, it'll not be as fast as a hand-written plug-in. Yet, if the formulas are not too complex, it is still quite fast. There will also be a tool to translate the formulas into C code, so there is another speed gain possible (although, again, this won't be as efficient as a hand-written plug-in).

Think of it as some kind of interpreter extension for The Gimp - but unlike script-fu or python-fu which are mainly used to combine effects, this is used to create effects.

This version of the User Filter plug-in is derived from the last (v0.8) version that was available back in 2003 (and which was just a compile-fix for the new Glib and Gtk+). A couple of bugs that were in the old version have been fixed, code that used deprecated functions was replaced, and the functionality of the plug-in was extended a little.

To get an idea what a filter description might look like, you can go to http://gimpuserfilter.cvs.sourceforge.net/gimpuserfilter/userfilter/src/test/ where you can find a few samples.

By default, these filter descriptions should be installed in ${gimp_dir}/userfilter:${gimp_data_dir}/userfilter But that's run-time configurable (you can change the search path from within the plug-in to any place where you would like to store filter descriptions). The plug-in will recursively search those paths for filters on start-up.

I will try to get some more information (and more important: documentation) on the project webpage during the weekend (though I can't promise anything).

Now some information for the old and grey who might still remember the original version of the plug-in...

You will certainly notice a couple of changes (besides a slightly different look). The most important is, that you cannot take any FF filter and place it in the userfilter data directory any more - you will have to import the filter through the editor and save it in the new .guf file format. This might sound inconvenient at first, but I have done this on purpose: The new data handling makes extension of filter functionality easy and also offers a means to include locale data (for filter controls etc).

hth for starters

Torsten

Hi,

If the goal is not reuse of existing filter but creating new ones from scratch there are already at least two solutions tackling it in slightly different ways.

http://www.complang.tuwien.ac.at/schani/mathmap/ and http://pippin.gimp.org/plug-ins/gluas/

Well, you can also re-use existing filters. In fact several hundreds that have been written for Filter Factory (not all of which may be useful though) and are either in the public domain or otherwise freely available.

MathMap might be the best of all solutions from what I see, but also the most complex. So far, UserFilter seems to be simpler to use for the average graphician (I think) - plus it is possible to have filter scripts installed in the Gimp's menu (which doesn't seem to be possible with gluas or mathmap and which I feel is important for working with a filter that has been created with such a tool).

But as you said: It is a different approach...

Torsten

Than why is my mathmap submenu overpopulated with various presets shipped with mathmap? :)

Oops ;-)

Ok, so I've overlooked something there... things happen

Thanks for pointing this out for me

Torsten