This work was done while the author was with the Department of Computer and Information Science, University of Pennsylvania. Ned Batchelder co-developed the original troff version of this program with the author, and was responsible for much of the overall design. For more detailed information on the original version of PostScript \ see Psfig -- A Ditroff Preprocessor for PostScript Figures in the USENIX 87 proceedings, or Bringing troff up to speed in the July 1987 issue of Unix Review.
Greg Hager provided the initial pure-TeX implementation of psfig. J. Daniel Smith of Schlumberger CAD/CAM implemented the rotation feature and improved the file scanning routines, using certain code fragments from Tom Rokicki's dvips program.