The THRESHOLD segmentation is conceptually simple. All pixels with value above or below the threshold are included in the segment, depending on the condition settings.
Sometimes it is helpful to segment at several threshold levels at once. This can easily be realized by setting the number in the Thresholds field accordingly, and entering the threshold values in the appearing Set dialog window.
Multiple threshold values can be incremented with a constant value enabling the Inc box and specifying the step in the dedicated text box.