My first plug-ins, but the writing seemed straight-forward enough. I
categorized them both as colormap (<Image>/Filters/Colors under GIMP v1.0).
If you untar (gzip -cd mandelbrot-invert.tar.gz | tar xvf -) and make
(make) in your .gimp/plug-ins directory, the GIMP should be able to find
them.  You may have to adjust the stated locations of libraries and includes
in the Makefile to fit your environment.  (Apologies if this is obvious; I
am writing for multiple audiences.)

"Mandelbrot Invert 1" inverts image pixels to display a view of the
Mandelbrot set, generated within a user-selected rect of the complex plane.
If a sampled point within the rect is found to be a member of the M-set,
the color/value of the corresponding image pixel is inverted.

"Mandelbrot Invert 2" inverts image pixels to display encirclement bands,
generated within a user-selected rect of the complex plane, that usually
appear adjacent the to Mandelbrot set.  The lower the number of iterations
required for the series sum calculated for a sampled point to diverge
beyond threshold, the more the color/value of the corresponding image
pixel is inverted.

Some samples of digital art I created using the algorithm for the first
plug-in (as a stand-alone program, before incorporation into the plug-in)
are viewable online in the Spotlight Corner of the Fractal Art Museum
<http://www.crosswinds.net/~fractalis/spot/kodstans.html>.  Thanks to
Joseph Trotsky for his generous comments.

A coherent and accessible write-up of the theory behind the Mandelbrot Set
is available in Gary William Flake's book, "The Computational Beauty
of Nature."  This book was the starting point and inspiration for much of
this work.

Usage suggestions:
Both "Mandelbrot Invert 1" and "Mandelbrot Invert 2" start with a square
rect by default.  To get a more accurate depiction of the Mandelbrot set
(which may or may not be important to you), you should set the height/width
proportions of the complex plane rect to be the same as the height/width
proportions of your image or selection.  If it's not clear how to use
the first four parameters to resize/rescale/reposition the rect, try
doubling or cutting the default values in half to see the effect.  As
far as the other two parameters of "Mandelbrot Invert 2," experiment.
If you go outside my suggested bounds, it shouldn't break anything (if it
does, let me know), but shouldn't output anything interesting either.
Note also that unlike most color filters, these also work on grayscale
images.  It's possible to get interesting abstract mist effects by
decomposing an image, applying one of the "Mandelbrot Invert" filters
to the saturation channel, and recomposing.

That's it.  Feedback, software development suggestions for
fixes/improvement, or interesting art use ideas/examples appreciated.

Stan Schwartz

    *                                                      Stan Schwartz *
    *                              Post-Conceptual and Computational Art *
    *                                     [EMAIL PROTECTED] *
    *                             <http://www.stanschwartzmeta-arts.com> *
    *                                                                    *
    *                                                                    *
    * "Nothing is true and everything is permitted."                     *
    *  William Burroughs                                                 *
    *                                                                    *
    * "All profoundly original art looks ugly at first."                 *
    *  Clement Greenberg                                                 *
    *                                                                    *
    * "The Net treats censorship as damage and routes around it."        *
    *  John Gilmore                                                      *
Gimp-user mailing list

Reply via email to