The availability of numerous colour maps (also known as gradients) adds great variety to the look of a fractal picture. When Saturn is started for the first time it has just five colour maps, “Default”, “Default 1”, “Default 2”, “Default 3” and “Default 4”, these maps always appear at the beginning of the list of colour maps and they can not be edited or deleted. The colour maps are held in an XML file called colour.xml which initially has no colour maps as the default maps are built into Saturn itself, colour maps can be added, edited, and deleted and will be stored in the colour.xml file when Saturn is shut down.
There are two types of colour map that can be created, manual and auto which can be selected using the “Auto” check box on the “Colour Maps” tab of the fractal settings window. The manual version is shown below:
Basic editing facilities are provided, the colour to be set in the map is selected using the colour selection widget and the position in the map is indicated using the “Index” spin button, the colour at the cursor can be deleted or its colour can be swapped with the colour at the position above or below it. If the colour is to be moved from say 127 to 186 it would have it be deleted from the map and re-entered at the new position. There is a maximum of 512 colours in a colour map, the number used however is determined by the largest index used, in this case 511 which of course results in the maximum of 512 colours. In this example colours are defined at only three locations, the colours at 1-126 and 128-510 are determined using straight line gradients.
Auto colour maps are generated from waveforms defined for each of the component colours: red, green and blue, an example of the auto version of the “Colour Maps tab is shown below:
There are three basic waveform types, sine, parabolic and saw. The amplitude of each waveform can be adjusted resulting in a straight line for zero, the waveform can be moved left and right using the horizontal offset, up and down using the vertical offset and the number of cycles can be changed. Up and down movement causes any part of the waveform that is outside the range 0-255 to be reflected, this effect is shown below.
Colour maps can not be saved unless the map is given a valid name that is not one of the default maps names. Note: the fact that the “Save” button is disabled is a bug.
So those are the two methods of creating, editing and deleting maps, producing maps in this way is time consuming, maps can be added easily using the import button. Saturn can import “gradients” defined in .ugr and .map files, the import of .ugr files only recognises the colours and their indexes so the import won’t be exact. When Saturn is released I’ll include a selection of .map and .ugr files, each .map contains a single colour map whereas a .ugr file can contain a great many. Every colour map whether created by the user or imported appears in the list of colour maps.
Changing the colour map in Saturn is easy, in the “Colour” tab the colour map list is displayed on the right hand side of the colour method settings and can be selected by clicking on required colour map name, once the list has focus the colour map can be changed by moving the list cursor up or down using the keyboard cursor keys, so trying out different colour maps can be performed very quickly. Unlike Gnofract4D changing the colour map does not cause the fractal to be recalculated unless the colouring method is one of the two Pickover Popcorn colouring methods that require re-calculation. Gnofract4D has two lists for its colour maps, a file list and a list of maps defined in the selected fil, I expected something similar in Ultra Fractal, I was wrong, it took a while to find out how to change colour maps in Ultra Fractal , it is is a multi-stage process and like Saturn does not cause the fractal to be recalculated.
Finally, colour maps for saved images are never lost as they are embedded in the png seed files along with all the other necessary parameters required to recreate the fractal image. When a seed file is opened by Saturn (by menu or dropping the file on the main window), each of the colour maps in the seed file is checked if they are recognised the appropirate map name is used, if not the map is inserted to the list of maps with a temporary name e.g. ~~~TEMPn (where n is number starting at zero, if the name already exists it is incremented until an unused temporary name is found).
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