A procedure for detecting contours automatically is particularly needed when processing sequences of cardiographic images. In fact, in this field the number of images to be processed is, in general, large enough to make a manual tracing phase unacceptable. In this paper a new approach to automatic contour detection from image sequences id presented. If a rough contour of the desired structure is available on the first frame, every contour of the sequence is automatically outlined. The entire process is based on two main steps carried out in turn. First, an image is convolved with a mask of suitable size in order to transform any discontinuity, such as the boundary of the structure one is looking;for, into a furrow of suitable width. Second, every point of a given starting contour, which is entirely contained inside the furrow, is made to fall to the bottom of the furrow by means of a localization algorithm, (C) 1994 Academic Press, Inc.