An image processing method for extracting a threadlike structure (GW) represented in an image, comprising a phase of acquisition (10) of a sequence of images, including an image of a present instant (t) in which the threadlike structure is to be extracted and an image of a past instant (t-1) in which the threadlike structure is detected as a string of points (G.sub.t-1), and further comprising a phase of prediction (20) of a silhouette (G.sub.t) of the threadlike structure estimated from said detected string of points (G.sub.t-1), of the image of the past instant, a phase of pursuit (30) for extracting a final string of points (G.sub.t) representing the threadlike structure in the image of the present instant t, including steps of estimation of constraints (C2.sub.t, .theta.) based on said silhouette (G.sub.t) for performing said extraction.