The color scale wizard is used to design color scales appropriate for the used data. It is made up of two pages:
- Design, where the user designs the raw color content of the color bar
- Map Data, where the user assigns values to the raw color bar based on map data
When closing the wizard the user is prompted for a file name for the color scale.
On the Design page the user designs the base colors for the color scale bar using an ordered list of colors.
Both the standard RGB method and the HSI method are supported.
Here the Number of colors on this list can be adjusted with the arrows. This will add or remove colors from the top of the list. It is also possible to right-click on the list to either Insert new color or Delete color a specific place on the list.
The base colors are selected by pressing the mouse button at one of the base colors in the list. Doing that shows a color select dialogue box with predefined colors and a tool for modifying RGB color channels to get the preferred base color.
Use Flip to reverse the list of base colors.
Here the list of colors have been replaced by an interval in the HSI color space. The interval is determined by a Start color and an End Color, each defined by Hue, Saturation and Intensity.
Hue is an angle between 0 and 360, saturation is a percentage between 0 and 100, and the intensity is a range from 1 to 255. The start values can be higher, the same or lower than the end values. The wheels are showing all hue values for the set saturation and intensity.
As each color can be specified in both RGB and HSI, the used color space will not affect discrete color scales. It does however affect smooth color scales since the interpolation between colors will be along the coordinates of the used color space.
The Number of levels correspond to the number of colors used by a discrete color scale. It has no effect on a smooth color scale that is defined solely by its begin and end points in the HSI color space.
The last option is to Copy to RGB color. This option makes it possible to transform the interval defined in the HSI color space into a RGB list of colors with as many colors as there are levels. It will no longer be a HSI color scale.
Here the color scale can be set to be Smooth or Discrete and the resulting color scale bar will be displayed. This color scale bar can then be tailored to the data on the next page to create the actual color scale.
On the Map data page, the user assigns values to the color scale bar based on the data.
The left side of the user interface contains a data histogram and the right side the color scale bar from the design page. The area between is used to draw connection lines (“mapping lines”) between data values and color scale values.
The connections will initially be connected equally spaced from the data side to the color side.
Smooth and Discrete color scales behave slightly differently to account for the very different ways they are used.
- For Smooth color scales the connections on the color side are connected to a value between 0 and 100% percent of the color scale value. This also means that the equally spaced connection lines will have no effect on the mapping of the colors. It is only when the connections are changed on either the data or color side, that they will affect the mapping of the colors.
- For Discrete color scales the connections on the color side are instead always connected to the nearest border between two base colors. This allows specific data ranges to be connected to specific discrete colors. It however also means that equally spaced connection lines can have a different number of discrete color borders between them and this will affect the mapping of the colors causing some colors to cover a larger data interval than others.
The Number of connections used to define the connections between the data values and the color values can be adjusted with the arrows.
The default distribution of the connections is linear, but when Logarithmic data transform is enabled, the connection lines will be distributed using the logarithmic function (base 10). At the same time the histogram will be redrawn so that the connection lines appear to be equally spaced on the data. This will also update the data values of the connections. The distribution of the data is not changed by this, it is only the connections that are distributed differently.
Selecting the Cumulative histogram mode will change the histogram chart to a cumulative histogram display. This has no effect on the data or the connections, it only affects how the histogram is displayed.
User defined data min/max or Histogram
It is possible to use another data range than the one given by the data:
- When selecting the User defined data min/max radio button, it becomes possible to specify the exact minimum and maximum values for the data range to be used.
- When selecting the Histogram radio button, it become possible to set a Cut off that removes a small percentage of the lower and upper part of the data. This can be used to enchance details in the resulting smaller data range without cutting out too much data.
The Number format of the axis labels can be changed using the dropdown. Note that it is possible to change the base formats suggested in the dropdown. Simply change ####0.0 to ####0.00 if that is more relevant.
If Automatic axis labels is disabled, it becomes possible to change the Number of labels with the arrows. This also changes the Preview of the color scale below, making it possible to edit the individual labels and having them displayed with a tick at exactly the values that are relevant. This is in addition to the automatic linear and logarithmic ticks.
The resulting color scale will be displayed here.
When editing a color scale from a single image, there will also be an image preview showing the effect of connection changes directly in the image.