PostScript definition language, text, graphics
A page description language
based on work originally done by John Gaffney at Evans and Sutherland in 1976, evolving through "JaM" ("John and Martin", Martin Newell) at XEROX PARC
, and finally implemented in its current form by John Warnock et al. after he and Chuck Geschke founded Adobe Systems, Inc.
PostScript is an interpreted
, stack-based language (like FORTH
). It was used as a page description language by the Apple LaserWriter, and now many laser printers
and on-screen graphics systems. Its primary application is to describe the appearance of text, graphical shapes, and sampled images
on printed or displayed pages.
A program in PostScript can communicate a document description from a composition system to a printing system in a device-independent way.
PostScript is an unusually powerful printer language because it is a full programming language, rather than a series of low-level escape sequences. (In this it parallels Emacs
, which exploited a similar insight about editing tasks). It is also noteworthy for implementing on-the fly rasterisation, from Bezier curve
descriptions, of high-quality fonts
at low (e.g. 300 dpi) resolution (it was formerly believed that hand-tuned bitmap fonts were required for this task).
PostScript's combination of technical merits and widespread availability made it the language of choice for graphical output until PDF
The Postscript point
, 1/72 inch, is slightly different from other point
An introduction (http://cs.indiana.edu/docproject/programming/postscript/postscript.html).
["PostScript Language Reference Manual" ("The Red Book"), Adobe Systems, A-W 1985].