Border detection of the object segmented by the pyramid linking method

The result of segmentation using the pyramid linking method is a subtree of links built above the segmented object. A modification of this algorithm is described which allows the author to trace only the links having the chance to reach the border pixels on the base level. The author´s technique detects the region outline (instead of the region itself) with the efficiency proportional to the border length. A special case is the detection of a border fragment shared by the two segmented objects.