The Draw transformation task draws regions, that were identified during analysis, on images or video frames.

By default, Media Server draws the regions described in the following table:

Face detection An ellipse that describes the position of a face. The ellipse is described by the ellipse element in the records created by face detection.
Number plate recognition A polygon that describes the position of the numberplate. The polygon is described by the plateregion element in the records created by number plate recognition.
Other tracks where the records contain regions If the record contains a polygon, Media Server draws the polygon. Otherwise Media Server draws the bounding rectangle for the region.

To draw outlines around multiple types of region, for example both detected faces and recognized logos, you can combine multiple tracks using a combine ESP task. The output from the combine ESP task, and therefore the input for the drawing task, is a track where records contain other records. In this case the drawing task iterates over the nested records.

You can configure the line color and line thickness that Media Server uses for drawing.

You can also customize the drawing task by writing a Lua script that defines the regions to draw. For example, if you run face detection and demographic analysis, you can write a Lua script to outline male and female faces in different colors.

The Draw task creates an output track named taskName.Output, where taskName is the name of the task. The images in this track are permanently modified (the regions that you draw on the images cannot be removed).