# Color legend layer

This viewport layer renders the color scale for a Color coding modifier or the list of discrete element types and corresponding colors into the output picture. The color legend helps viewers to associate object colors with corresponding numeric values or element types. The following figure shows two typical examples of color legends: A color map for a continuous particle property and a discrete color legend for the `Particle Type` property:

## Color source

The selected Color legend source determines where the legend takes its colors from. In the current program version, three types of sources are available in the drop-down list:

Color coding modifier

  If the current data pipeline contains a Color coding modifier, the legend can display its gradient and min/max value interval.

Typed properties

  Alternatively, the legend can display a list of discrete element types associated with a typed property in the data pipeline’s output. Typical examples are the particle properties `Particle Type`, `Structure Type` or `Residue Type`. The legend will display the name and color of each type defined for the selected source property.

  Note

  Note that the color legend layer itself is not responsible for coloring the particles or bonds. It may be necessary to insert a Color by type modifier into the pipeline to actually give particles and bonds their corresponding colors.

Pseudo color mappings

  Some of the visual elements provide an option to color objects or surfaces based on a local property. If such a color mapping function has been activated for some visual element in the scene, it can be selected as the source of the color legend layer.

## Parameters

The other parameters of the color legend layer let you control the size, positioning and appearance of the color legend in the rendered picture. By default, the legend will be labeled with the name of the source property and, if based on a Color coding modifier, the numeric range set for that modifier. You can override the text of the labels by entering something into the input fields Custom title and Custom label.

Note

It is possible to include HTML markup elements in the label texts to format them, e.g., to produce special notations such as superscript or subscript. See here for further information.

If the legend associated with a Color coding modifier, the numeric format of the min/max values is controlled by a format specification string. You have the choice between decimal notation (`%f`), exponential notation (`%e`) and an automatic mode (`%g`), which picks the best representation depending on the value’s magnitude. The format string also gives you explicit control over the output precision, i.e. the number of digits that appear after the decimal point. Use `%.2f`, for example, to always show two digits after the decimal point. The format string must follow the rules of the standard printf() C function.

Furthermore, it is possible to include a physical unit as part of the format string, e.g. `%g eV`.

See also

`ovito.vis.ColorLegendOverlay` (Python API)