Tag: postscript

About

PostScript (PS) is a page description language and programming language used primarily in the electronic and desktop publishing areas.

The concepts of the PostScript language were seeded in 1976 when John Warnock was working at Evans & Sutherland, a famous computer graphics company. At that time John Warnock was developing an interpreter for a large three-dimensional graphics database of New York harbor. Warnock conceived the Design System language to process the graphics, very similar to the Forth programming language.

Concurrently, researchers at Xerox PARC had developed the first laser printer and had recognized the need for a standard means of defining page images. In 1975-76 a team led by Bob Sproull developed the Press format, which was eventually used in the Xerox Star system to drive laser printers. But Press, a data format rather than a language, lacked flexibility, and PARC mounted the InterPress effort to create a successor.

In 1978 Evans and Sutherland asked Warnock to move from the San Francisco Bay Area to their main headquarters in Utah, but he was not interested in moving. He then joined Xerox PARC to work with Martin Newell. They rewrote Design System to create JaM (for "John and Martin") which was used for VLSI design and the investigation of type and graphics printing. This work later evolved and expanded into the InterPress language.

Warnock left with Chuck Geschke and founded Adobe Systems in December 1982. They created a simpler language, similar to InterPress, called PostScript, which went on the market in 1984. At about this time they were visited by Steve Jobs, who urged them to adapt PostScript to be used as the language for driving laser printers.

In March of 1985, the Apple LaserWriter was the first printer to ship with PostScript, sparking the desktop publishing (DTP) revolution in the mid-1980s. The combination of technical merits and widespread availability made PostScript a language of choice for graphical output for printing applications. For a time an interpreter (sometimes referred to as a RIP -for Raster Image Processor) for the PostScript language was a common component of laser printers, into the 1990s.

Once the de facto standard for electronic distribution of final documents meant for publication, PostScript is steadily being supplanted by one of its own descendants, the Portable Document Format or PDF in this area. By 2001 there were fewer printer models which came with support for PostScript, largely due to the growing competition from much cheaper non-PostScript ink jet printers (PostScript interpreters added significantly to printer cost), and new software-based methods to render PostScript images on the computer, making them suitable for any printer (PDF provided one such method). The use of a PostScript laser printer still can, however, significantly reduce the CPU workload involved in printing documents, transferring the work of rendering PostScript images from the computer to the printer.

PostScript Level 1

The PostScript language has had two major upgrades. The first version, known as PostScript Level 1, was introduced in 1984.

PostScript Level 2

PostScript Level 2 was introduced in 1991, and included several improvements: improved speed and reliability, support for in-RIP separations, image decompression (for example, JPEG images could be rendered by a PostScript program), support for composite fonts, and the form mechanism for caching reusable content.

PostScript 3

PostScript 3 (Adobe dropped the "level" terminology in favor of simple versioning) came at the end of 1997, and along with many new dictionary-based versions of older operators, introduced better color handling, and new filters (which allow in-program compression/decompression, program chunking, and advanced error-handling).

PostScript 3 was significant in terms of replacing the existing proprietary color electronic prepress systems, then widely used for magazine production, through the introduction of smooth shading operations with up to 4096 shades of grey (rather than the 256 available in PostScript 2), as well as DeviceN, a color space that allowed the addition of additional ink colors (called spot colors) into composite color pages.

From en.wikipedia.org/wiki/PostScript