This filter is found in
This fractal-based plug-in is truly wonderful! With this
versatile instrument, you can create amazingly naturalistic
organic shapes, like leaves, flowers, branches, or even whole
trees. ("IFS" stands for "Iterated Function System".)
The key to using this plug-in lies in making very small and
precise movements in fractal space. The outcome is always hard
to predict, and you have to be extremely gentle when you change
the pattern. If you make a component triangle too big, or if you
move it too far (even ever so slightly), the preview screen will
black out, or more commonly, you'll get stuck with a big
shapeless particle cloud.
A word of advice: When you have found a pattern you want to work
with, make only small changes, and stick to variations of that
pattern. It's all too easy to lose a good thing. Contrary to
what you might believe, it's really much easier to create a leaf
or a tree with IFS Compose than to make a defined geometrical
pattern (where you actually know what you're doing, and end up
with the pattern you had in mind).
For a brief introduction to IFS's see Foley and van Dam, et
al,. Computer Graphics, Principles and
Practice, 2nd Ed., (Addison Wesley, 1990).
The Main Interface
The plug-in interface consists of the compose area to the left, a
preview screen to the right, and some tabs and option buttons at
the bottom of the dialog. The Default setting (in the preview
window) is three equilateral triangles. (This gives rise to a
fractal pattern called the Sierpinski
Some tools are directly visible in this tool bar:
You can see others, if your window is not wide enough, by
clicking on the drop-down list button on the right of tool bar:
Render Options where you have have
Enables you to speed up rendering time. This is
especially useful when working with a large spot
radius; just remember to use even multiples of the
default value: 4096, 8192, 16384, ...
Determines how many times the fractal will repeat
itself. (A high value for Subdivide and Iterations is
for obvious reasons a waste of process time unless
your image is very large.)
Controls the level of detail.
Determines the density of the "brushstrokes" in the
rendered image. A low spot radius is good for thin
particle clouds or spray, while a high spot radius
produces thick, solid color strokes much like
watercolor painting. Be careful not to use too much
spot radius -- it takes a lot of time to render.
Gives you information on the active fractal, and allows
you to type a value instead of changing it
manually. Changing parameters with the mouse isn't very
accurate, so this is a useful option when you need to be
"Color transformation" tab options
Simple color transformation
Changes the color of the currently selected fractal
component (which starts as the foreground color in the
toolbox) to a color of your choice.
Full color transformation
Like the Simple color transformation but this time you can
manage the color transformation for each color channel and
for the alpha channel (shown as a black channel).
When you have many fractals with different colors, the
colors blend into each other. So even if you set "pure
red" for a fractal, it might actually be quite blue in
some places, while another "red" fractal might have a lot
of yellow in it. Scale Hue/Value changes the color
strength of the active fractal, or how influential that
fractal's color should be.
Determines influence or total impact of a certain fractal.
A Brief Tutorial
This is a rather complex plug-in, so to help you understand it,
we'll guide you through an example where you'll create a leaf or
Many forms of life, and especially plants, are built like
mathematical fractals, i.e., a shape that reproduces or repeats
itself indefinitely into the smallest detail. You can easily
reproduce the shape of a leaf or a branch by using four (or
more) fractals. Three fractals make up the tip and sides of the
leaf, and the fourth represents the stem.
Before invoking the filter: Select
Add a transparent layer with
Layers->Layers and Channels->New Layer
Set the foreground color in the toolbox to black, and
set the background to white.
Open IFS Compose. Start by rotating the right and bottom
triangles, so that they point upward. You'll now be able to
see the outline of what's going to be the tip and sides of
the leaf. (If you have problems, it may help to know that
the three vertices of a triangle are not equivalent.)
Tutorial Step 2
Start by rotating triangles 2 and 3, trying to keep them nearly
the same size.
To make the leaf symmetrical, adjust the bottom triangle to
point slightly to the left, and the right triangle to point
slightly to the right.
Press New to add a component to the
composition. This is going to be the stem of the leaf, so we
need to make it long and thin. Press
Stretch, and drag to
stretch the new triangle. Don't be alarmed if this messes up
the image, just use Scale to adjust
the size of the overlong
triangle. You'll probably also have to move and rotate the
new fractal to make it look convincing.
Tutorial Step 3
Add a fourth component, then stretch, scale, and move it
You still have to make it look more leaf-like. Increase the
size of the top triangle, until you think it's thick and
leafy enough. Adjust all fractals until you're happy with
the shape. Right-click to get the popup menu, and choose
Select all. Now all components are
selected, and you can scale
and rotate the entire leaf.
Tutorial Step 4
Enlarge component 1, arrange the other components
appropriately, then select all, scale and rotate.
The final step is to adjust color. Click on the
Color Transformation tab, and choose
a different color for each fractal. To do this, check
Simple and press the right color
square. A color circle appears, where you can click or
select to choose a color.
Tutorial Step 5
Assign a brownish color to component 4, and various shades
of green to the other components.
Press OK to apply the image, and voilà, you've just made a
perfect fractal leaf! Now that you've got the hang of it,
you'll just have to experiment and make your own
designs. All plant-imitating fractals (be they oak trees,
ferns or straws) are more or less made in this fashion,
which is leaves around a stem (or several stems). You just
have to twist another way, stretch and turn a little or add
a few more fractals to get a totally different plant.