  Stress and strain fields in a two-dimensional pixelwise disordered system are
computed by a Fast Fourier Transform method. The system, a model for a ductile
damaged medium, consists of an elastic-perfectly matrix containing void pixels.
Its behavior is investigated under equibiaxial or shear loading. We monitor the
evolution with loading of plastically deformed zones, and we exhibit a
nucleation / growth / coalescence scenario of the latter. Identification of
plastic ``clusters'' is eased by using a discrete Green function implementing
equilibrium and continuity at the level of one pixel. Observed morphological
regimes are put into correspondence with some features of the macroscopic
stress / strain curves.
