
segmentation method makes use of this phenomenon [28]. In this technique, one
first thresholds the gradient at a moderately low level to identify the object and
the background, which are separated by bands of edge points that are above
threshold. Then the threshold is gradually increased. This causes both the object
and the background to grow. When they touch, they are not allowed to merge;
rather, the points of contact define the boundary. This is essentially an application
of the watershed algorithm to the gradient image.
While this method is computationally more expensive than thresholding, it
tends to produce maximum gradient boundaries, and it