Today a person nicknamed sigtech of GIMP Painter project announced availability of several patches to user interface and painting functionality of GIMP. The news are going to hit websites anyway, so best it to get things right from the beginning.

Let's start with what GIMP Painter is. It's a fork of upstream GIMP that implements some painting related functionality that creators of the fork found missing in GIMP. Up till now two most significant changes were:

Mixbrush, a painting tool that allows natural paints blending;

G-Pen, a fork of GIMP's Ink tool that implements optional line smoothing.

If you want demonstration of Mixbrush, watch these two videos created by Yoshinori Yamakawa who is involved in the GIMP Painter project:

GIMP Painter was used in "Chaos and Evolutions" DVD course on digital painting by David Revoy (it was shipped with DVD too) and GIMP Paint Studio actually makes presets for GIMP Painter rather than for regular GIMP.

So, what's in the new bundle of patches?

Horizontal tool options toolbar instead of of vertical. Vertical tabs in docks and therefore vertical docking (or vice versa). Tabs in painting dynamics editor. Folding of docks. Changes in brush palette interface. Blending modes and working painting dynamics for Smudge tool (dynamics are broken for Smudge currently in upstream GIMP); Line smoothing. The former G-Pen implementation worked for the forked Ink tool only. The new patch implements smoothing for both brush core and the Ink tool, so it should work for all brush based tools (including Smudge and Clone), Airbrush tool and Ink tool.

What does it look like? Here is a screenshot of today's Git created by GIMP Painter's developer:

One cannot help but noticing the UI looks rather Photoshop-ish :)

OK, so what's the deal? Will these changes be merged to upstream GIMP? The answer is a bit more complicated than you probably expect.

First of all, the new changes can be roughly divided into controversial and non-controversial. The painting related changes are non-controversial and will be merged into upstream. The user interface changes are a different story.

One thing that has to be understood about the way GIMP is evolving for last few years is that it's been shaping up according to a big picture: what it aims to be, what the target user base is and so on. The UI patches implemented by sigtech are based on requests from GIMP UI brainstorm blog and thus, whether "good" or "bad" they are, haven't been considered as part of the big picture yet. So the UI changes will have to wait till they are taken through the usual usability routine by Peter Sikking, GIMP's usability architect.

The first good news is that sigtech expressed willingness to cooperate with upstream GIMP project. The second good news is that two paid internships that Peter Sikking proposed are currently rolling out, which presumably will help unlocking development of last missing bits in 2.8 (most notably, the optional single-window mode).

That still leaves us Mixbrush. The thing about Mixbrush is that it's a painting tool that is still based on the old GIMP core, whereas the current project's policy is to not accept new tools based on the old core and request using GEGL instead. This is why the new Cage transform tool was designed and implemented as GEGL based. According to Alexia, who is currently in charge of painting features in GIMP, GEGL's painting core can have multiple external rendering engines, so the right way to implement Mixbrush is to do it using GEGL.

If you are keen to play with the new GIMP Painter, right now you can only clone Git repository and build source code. The Git repo of the fork is kept in sync with upstream GIMP's Git master repository.

Edit: as of October 2011 there is an Ubuntu PPA for GIMP Painter.