Abstract: This relates to a filtering method for processing an image sequence, including for each image parallel binarizations of the gray levels, provided to define a tree structure made of a father node (c.sub.0.sup.1) corresponding to a background (A0) and of successive child nodes (C.sub.h.sup.k) corresponding to associated connected components (B1, D1, F1, C2, E2, G2) and a decision on the elimination or the preservation of each node (C.sub.h.sup.k), followed by an assignment of a gray level value to each picture element. This type of filtering offers the advantage of simplifying the images as well as perfectly preserving the contours, and the decision is based on various proposed simplification criteria, among which the motion-oriented one is particularly attractive.