Abstract: A semi-automatic method of extracting a contour in a digital image using a combined active contour and starter/guide approach is based on an iterative process of deforming an active contour to obtain a current trace and extending the current trace by a straight line segment. An initial contour is entered into the image to seed the iterative process. Local analysis of the digital image at a point of the initial contour determines a first reference datum. At each iteration this analysis is carried out locally at a plurality of points around the end point of the current trace to determine, by correlation with the first datum, the orientation of the straight line segment extending the current trace.

Abstract: A method of extracting a contour of a contrasted area in a digitized image made up of pixels having different intensity levels defining the contrasted area is based on minimizing the energy of an initial active contour to which are applied stresses derived from a potential image obtained by processing the image. The potential image is obtained from a multifractal analysis of the image so that each element of the potential image is representative of a local fractal dimension in the locality of a corresponding pixel in the image. This improves the behavior of the active contour when it is deformed by the stresses.