Levy-Vehel, J.Gagalowicz, A.2015-10-052015-10-0519881017-4656https://doi.org/10.2312/egtp.19881024We present some new techniques for shape approximation with fractals, using Iterated Function System, a powerful method which allows good control on the resulting fractal. The main point discussed here can be stated as follows : given a grey level image A, find a few number of functions and associated probabilities that approximately generate A. Two directions have been explored : the first uses a gradient method, thus it was necessary to define a smooth error function ; the second one is based upon the ideas of simulated annealing. We then generalize the methods to a broader class of functions, and present some results.10.2312/egtp.19881024