Contour

The contour tool is useful in situations where you have many objects that you have to label, and those labels have a clear contour - meaning contrast between them and the background. If those conditions are met, the tool allows you to create new objects by through a simple point-and-click interaction, saving you time in comparison with having to do the work manually.

The tool can be accessed by pressingor by pressing “C”.

Using the Contour Tool

When the tool is selected, you should see orange shapes in the work area. These shapes show you potential objects. By left-clicking on one of those shapes, you create a new object. If you don’t see any orange shapes or if they are not covering the objects in the way that you want, try to adjust the threshold.

This candy dataset with it's white background is an example of where the contour tool can help

Threshold

This modifier allows you to find different contours based on its value. What the threshold does, is look at certain ranges between completely white (100%) and completely black (0%). The modifier can be changed by adjusting the value in the tool settings bar or by using the hotkeys “,” and “.”. In practical terms, this means that you should move the threshold down when trying to find dark objects on a white background, and move it up if you want to find lighter objects on a dark background.

Here we adjust the threshold from 34% to 68%