Post Script (PS) is created byJohn Warncock and Charles Geschke in 1982 which is a dynamically typed concantenative programming language. It is also known for its use as a page description language in the electronic and desktop areas.
Before the introduction of PostScript, printers were designed to print character output given the text - typically in ASCII - as input. There were a number of technologies for this task, but most shared the property that the glyphs were physically difficult to change, as they were stamped onto typewriter keys, bands of metal, or optical plates. PostScript went beyond the typical printer control language and was a complete programming language of its own. Many applications can transform a document into a PostScript program whose execution will result in the original document. This program can be sent to an interpreter in a printer, which results in a printed document, or to one inside another application, which will display the document on-screen. Since the document-program is the same regardless of its destination, it is called device-independent. When the PostScript program is interpreted, the interpreter converts these instructions into the dots needed to form the output. For this reason PostScript interpreters are also sometimes called PostScript Raster Image Processors, or RIPs.
Almost as complex as PostScript itself was its handling of fonts. The rich font system used the PS graphics primitives to draw glyphs as line art, which could then be rendered at any resolution. Though this sounds like a reasonably straightforward concept, there were a number of typographic issues that had to be considered.
One issue is that fonts do not actually scale linearly at small sizes; features of the glyphs will become proportionally too large or small and they start to look wrong. PostScript avoided this problem with the inclusion of hints which could be saved along with the font outlines. Basically they are additional information in horizontal or vertical bands that help identify the features in each letter that are important for the rasterizer to maintain. The result was significantly better-looking fonts even at low resolution; it had formerly been believed that hand-tuned bitmap fonts were required for this task.
PostScript is a Turing-complete programming language, belonging to the concatenative group. Typically, PostScript programs are not produced by humans, but by other programs. However, it is possible to write computer programs in PostScript just like any other programming language. PostScript is an interpreted, stack-based language similar to Forth but with strong dynamic typing, data structures inspired by those found in Lisp, scoped memory and, since language level 2, garbage collection.
Today, third-party PostScript-compatible interpreters are widely used in printers and multifunction peripherals (MFPs). For example, Zoran Corporation's IPS PS3 interpreter, formerly known as PhoenixPage, is standard in many printers and MFPs, including those developed by Hewlett-Packard and sold under the LaserJet and Color LaserJet lines. Other third-party PostScript solutions used by print and MFP manufacturers include Jaws and Harlequin, both provided by Global Graphics.
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