Image processing puts heavy demands on computational speed and storage space. The PICAP system of Linkoping University has been designed to meet these demands in an interactive image processing environment, utilizing state-of-the-art hardware and software components. PICAP is a multiuser system, and computational speed is achieved through parallelism at both global and local levels. A virtual image memory alleviates the problem of storage space. The users can invoke the PICAP facilities by means of a menu-based language or a general-purpose high-level language. The modular and open-ended architecture of PICAP makes it highly adaptive to future advances in both hardware and software technologies.