PostScript Laser Printers

The situation changed dramatically in 1985 with Adobe’s announcement of PostScript Level 1, based on Forth and arguably the first standard multi-platform device-independent page description language. PostScript describes pages in outline, vector form which is sent to the display or printing device to be converted into dots (rasterised) at the device’s best ability. A monitor could manage 75dpi, a laser 300dpi and an image-setter up to 2400dpi. Each one produced more faithful representations of the PostScript description than the last, but all had the sizes and positions of the shapes in common. Hence device independence and the birth of the acronym, WYSIWYG – What You See Is What You Get.

PostScript Level 1 appealed to the high-end publishers thanks mostly to the fact that proofs made on a 300dpi laser would be laid out identically to those on 2400dpi image setters used to make film. Furthermore, it was possible to send the PostScript instructions from any platform. All that was required was a driver to turn the document information into PostScript which could then be understood by any PostScript printer. These features coupled with graphics snobbery, particularly amongst the Apple Macintosh community, and the fact that Adobe is the only official licenser, made PostScript-equipped devices ultimately desirable and consequently expensive.

PostScript Level 2, released a few years ago, offered device-independent colour, data compression for faster printing, and improved halftone algorithms, memory and resource management. PostScript Extreme (formerly called Supra) is Adobe’s newest variant, aimed at the top level of high-volume, high-speed printing systems like digital presses.