Levy-Vehel, J.Gagalowicz, A.2015-10-052015-10-0519871017-4656https://doi.org/10.2312/egtp.19871013The use of fractals to synthesize complex objects is of current interest in the computer graphics community. A powerful way to compute fractals is the use of IFS (iterated function system) which is a set of contractions with associated probabilities which characterize the fractal. This theory, developed by M. Barnsley and al., can produce very complicated objects. We present a method to solve the inverse problem for these globally constructed fractals : given a set A (attractor), find an IFS that will approximately generate A. We use an optimisation method to minimize a distance between A and the current set L. Several distances have been tested and an algorithm has been implemented which gives good results. A test image is presented.10.2312/egtp.19871013