One of the aims of modern microscopy is to quantify two-, three-, or even four-dimensional phenomena in biology, medicine, and material sciences. The requirements imposed on software by such data processing are exemplified by the design considerations of the IMAGIC-5 software system. This system includes facilities for multivariate statistical analysis of large data sets, for correlation averaging of two-dimensional crystals, and for three-dimensional reconstruction of macromolecular structures. The molecules may be arranged as two-dimensional crystals, as helices, or as single particles with arbitrary pointgroup symmetry. IMAGIC's novel angular reconstitution approach allows for the rapid determination of three-dimensional structures of uncrystallized molecules to high resolution. The general organization, user interaction strategy, file structure, and extendibility of IMAGIC are discussed and illustrated with some practical examples.