postscript Getting started with postscript General Description of PostScript


PostScript is a Turing-complete general programming language, designed and developed by Adobe Systems. Many of the ideas which blossomed in PostScript had been cultivated in projects for Xerox and Evans & Sutherland.

Its main real-world application historically is as a page description language, or in its single-page EPS form a vector-graphics image-description language. It is dynamically-typed, dynamically-scoped, and stack-based which leads to a mostly Reverse Polish syntax.

There are three major releases of PostScript.

  1. PostScript Level 1 — this was released to the market in 1984 as the resident operating system of the Apple LaserWriter laser printer, inaugurating the Desktop Publishing Era.
  2. PostScript Level 2 — released in 1991, this contained several important improvements to Level 1, including support for image decompression, in-RIP separation, auto-growing dictionaries, garbage collection, Named Resources, binary encodings of the PostScript program stream itself.
  3. PostScript 3 — the latest and perhaps most widely adopted version was released in 1997. It too contains several import improvements over Level 2 such as Smooth Shading. The term “level” has been dropped.

Though PostScript is typically used as a page description language -- and therefore is implemented inside many printers to generate raster images -- it can also be used for other purposes. As a quick reverse-polish calculator with more memorable operator names than bc. As an output format generated by another program (usually in some other language).

Though PostScript file are typically 7-bit-clean ASCII, there exist several kinds of binary encoding described in the level 2 standard. And being programmable, a program may implement its own arbitrarily-complex encoding scheme for itself. There is an International Obfuscated Postscript Competition, somewhat less active than the C one.

Online References



  • Postscript Language Reference Manual, 1ed, 1985. Recommended for its small size, and easy operator index from the summary pages (missing from later editions).

  • Real World Postscript. Chapters by various authors on various topics, including excellent coverage of halftoning.