What is itgrapher?
itgrapher is short for Iterative Transformation Grapher. It's a Python-Fu GIMP plugin for rendering images from math equations. You can generate fractals with it and more traditional functions. However, it is intended less for technical pursuits and more for artwork.
"Transformation" because it allows you to provide mathematical expressions (as functions of x and y, in Python syntax) that define a mapping from one set of (x,y) coordinates to another set of (x,y) coordinates. "Iterative" because it will repeat the transformation on the resulting coordinates. "Graphing" because it allows you to assign colors to the original coordinates based on the results of the iterative transformations. See more details below.
Download
Click here to download itgrapher.py
Installation
These instructions assume you have Gimp 2.4 and Python installed and working with other GIMP plugins. I know, I know: big assumption. I'll fill in more details later.
Windows
Put itgrapher.py in the lib/gimp/2.0/plug-ins directory under your GIMP installation (usually c:\program files\Gimp-2.0) and then start the GIMP. (This assumes you have a version of the GIMP that has PythonFu working).
Linux
Put itgrapher.py in your ~/.Gimp-2.4/plugins directory, set it to executable and then start the GIMP. (This assumes you have python installed in your Linux distro. If not, it is available on most package managers.)
Mac
First, right-click (control-click) on the GIMP application and "Show Package Contents". Put itgrapher.py in the Contents/Resources/lib/gimp/2.0/plugins directory, set it to executable and then start the GIMP. (This assumes you have python installed. You should if you have a recent MacBook Pro or better.)
itgrapher also supports Google's mpmath. You can use this when you want to work with really large numbers, deal with imaginaries, raise negative numbers to fractional exponents and all sorts of cool stuff. It's slow for normal operations, so it's off by default. If you aren't using mpmath, it doesn't need to be installed for itgrapher to run. In the latest version, the mpmath support is commented out to save space in the plugin window. You can uncomment all the lines that refer to "mpmath" if you want to use it. To find out more about mpmath including how to install it at http://code.google.com/p/mpmath/
Getting Started
First, open a new image. The size you choose with determine the area rendered. itgrapher ignores the selection. In our example image below we chose 200x150. It's a thumbnail size for quickly rendering before working on a larger image.
Using the menus on the newly opened image window, you will find itgrapher under Filters/Render.
This is what it looks like when you open it:
More instructions to come.