This segmentation tool is intended to be used on a classification image. (It partitions a classified image into regions of connected pixels or blobs of pixels that are contained in the same class. Each connected region is given a unique DN value.) The threshold values would indicate which classes you wish to include in the segmentation. So, for example if you wish to make segments for only the first class, you would enter 1 for both the minimum and the maximum.If you wish to make segments for the first two classes, you would enter 1 for the minimum and 2 for the maximum. - Peg Exelis VIS Tech Support