A time shared television digital image processing system has been developed for on-line electron microscopy and uses a large mainframe computer. The main component of the system is a digital television frame store which has many standard features for digital analysis such as: digitization, zoom and pan, arithmetic and Boolean processors, alphanumeric generators and so on. Images can be acquired at atomic resolution from a TEM, analyzed in real time and hard copy slides made under full computer control. A full range of computer software has been developed or modified from existing software and is generally compatible with IBM Fortran compilers. Some of the areas where extensive menu driven software has been developed are: particle size and feature analysis, algebraic and geometric image manipulations, Fourier analysis, digitization and process control, image contrast correction, text processing, etc. A number of applications areas have been explored which include: the structure of Si/SiO2 interfaces; nucleation of Au on rocksalt; the formation of hexatic structures from amorphous phases under shear, tension and compression; analysis of atomic surface structure and image motion and the analysis of field ion micrographs of amorphous structures. Several of these areas will be discussed in the context of image processing and materials characterization.