Color schemes can be selected and customized via the Color map menu. Coloring is applied to both interior and exterior points. The former lie inside the fractal, i.e., they are attracted to a cycle or a single fixed point, whereas the latter typically escape to infinity. For both types of points there are various options for coloring, depending on the escape times, the distances, the angles, and so forth, as well as various predefined coloring methods. Note that it is possible to define tiger stripes for exterior points. Depending on whether or not a point's escape time is even or odd, the color map switches between the main one and the tiger striping one.
Color maps can be inverted (e.g., going from white to black instead of black to white) or wrapped around (e.g., going from black over grey to white, returning over grey to black).
There is a range of default color maps available, and it is possible to modify these or create a custom color map.
Traditionally, colors are linearly interpolated across the specified color map, based on the minimum and maximum value occurring within the calculated fractal. This can lead to an inbalance typically seen when there are vast regions of constant values with rapidly increasing values near the border between interior and exterior points. In order to compensate for this effect, you can scale the color map. Possible methods are logarithmic, exponential, and square root scaling. Each time, you can specify the parameters for these scaling properties. A more powerful method that superseeds modern histogram coloring is based on rank order scaling, in which the probabilities of using the colors are all equal. Because this technique can smear out the more extreme high values, you can select the Restrict high iteration count colors option. This will effectively apply a logarithmic scaling after the rank order scaling.
Note that when the Cycle colors menu option is selected, Fraxion will cycle through all the colors in the chosen color map in real-time. This is a rather time consuming process, as the 24-bit colors are calculated instead of just being taken from a lookup table.
A selection of predefined color maps is available, as shown in the following submenu (all colors are linearly interpolated).
Aside from using one of the predefined color maps, you can also create your own custom color map. To that end, select the Set custom color map components option from the Specify interior/exterior color map submenu. This will give the following dialog, allowing you to modify 10 control points (locations and colors). By selecting the Convert current color map to custom option from the submenu, you can modify one of the predefined color maps.
There is a wide variety of coloring methods available, with the simplest one based on discrete level sets (i.e., the escape times), resulting in typical visible banding. In case of Newton / Raphson fractals, the color options will also enable coloring of roots (if they are tracked), both discrete and smooth.
For quick reference, Fraxion also allows you to select a predefined coloring method, as shown in the following examples. You can always go back to the default by selecting the Reset to default color map settings option from the menu. In that case, the color map reverts to the Jet color map, and using normalized level sets, no tiger striping, linear scaling, no inversion, wrapping, repetition, offset, or limited range.
Once an coloring scheme is selected, you can apply a chain of post- processing filters to the final image. There are five filters available, i.e., blurring, sharpening, edge/contour detection, color inversion, and color posterizing. For blurring and edge/contour detection you can specify the kernel size and strength, respectively. If the Auto proof checkbox is ticked (by default), then the filter chain is automatically previewed on the visible fractal.
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