DIGITAL IMAGE-PROCESSING OF ELECTRON-MICROGRAPHS - THE PIC SYSTEM-III

The PIC system is an integrated package of image processing software w ritten in Fortran and G. Throughout its 16 years of continuous develop ment, PIG has been designed for the processing of electron micrographs with emphasis on the particular requirements for structural analysis of biological macromolecules. PIG has been implemented on successive g enerations of Digital Equipment Corporation dedicated minicomputers an d workstations, The latest version, PIG-III, runs on Alpha workstation s and represents a substantial upgrading in functionality compared wit h PIG-II, the VAX version previously described (B. L. Trus et al. (199 2), Scanning Microsc. Suppl. 6, 441-451), PIG now possesses an X-windo ws menu-driven graphical user interface that many be utilized from bot h local or remote X-window terminals or workstations. Other new featur es include dynamic memory allocation; an open systems approach to inte rfacing with other image processing software packages; interface optio ns with visualization software; and programs to reconstruct three-dime nsional density maps of both helical filaments and free-standing parti cles with and without symmetry. (C) 1996 Academic Press, Inc.