THE POSTSCRIPT REVOLUTION

In the past twenty years the world of computers has witnessed the «PostScript» revolution. PostScript was developed by Adobe Systems, Inc. in 1982 as a page description language for printers like Apple LaserWriter and Allied Linotronic photosetters, among other output devices. Today it is used in most laser printers and is becoming a standard for high-quality type and graphics.

PostScript is mainly used to describe the appearance of text, graphics and images on the printed page. It works in «vectorial format», which means that it stores graphics not as images made up of dots but as geometric descriptions, in equation form. This allows text fonts and gra­phics to be enlarged or reduced with no loss of quality in the output.

A PostScript file consists of two main parts: the «prolog», which contains a set of subroutines used to form different graphic elements (rectangles, curves, etc.), and the «script», which contains the elements introduced by the user. The script calls up the subroutines stored in the prolog and add the parameters: for example, if you have drawn a square of 10r5 cm, the script calls up the subroutine Square and specifies the values 10r5.

All the features of PostScript can be used with Macintosh, Windows or OS/2 environments. PostScript is device-independent, which means that it can speak to different output devices (printers, film recorders, and imagesetters) and adjust the quality of the final output to the highest capabilities of the output devices. As for the computer, you only need a machine able to send a file to an output device containing a PostScript interpreter.

Each PostScript-based printer has a microprocessor, at least 2 MB of RAM, and an operating system that interprets the PostScript code. In the case of imagesetters, the hardware that interprets the code is called a Raster Image Processor.

Some drawing programs can produce pictures drawn in PostScript directly. These programs, such as Illustrator, Freehand, or CorelDraw, can often give more precise control over drawing than non-PostScript packages. Pictures created in PostScript and saved as separate files (known as Encapsulated PostScript — EPS — files) can be imported into a document generated by page-layout applications like PageMaker or QuarkXPress.

PostScript is an indispensable tool for illustrators, graphic designers and DTP professionals, and has become a universal device-independent data vehicle. It has support for sound, video and other formats: you can rotate portions of the page, mix scanned images, specify halftone screens and introduce any number of effects. In fact, the only barrier is your imagination.

Поиск по сайту: