Interactive image processing with an off-line minicomputer: organization, performance and applications.

A recently established facility for interactive image processing is described, primarily from the point of view of the system's hardware organization and the special purpose software provided to support it. The performance of more general software (the 'Semper' system) in the new environment has been measured carefully, and found to be about 10 times its performance on our previous PDP 8/E computer; particular attention is given to the data management techniques crucial to the system's efficiency. Some current applications are illustrated, including high resolution image interpretation and image averaging of biological crystals.