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Printer Languages and Technologies |
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Written by printadvise
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Sunday, 13 January 2008 |
Printer languages are commands from the computer to the printer to tell the printer how to prepare the document, which is going to be printed. These commands manage font size, graphics, compression of data sent to the printer, color, etc.
After the computer (print server) sends the spooled print job to the printer, the data is stored in the printer’s memory. Then the printer’s Interpreter handles the print job. It is the main part of the printer device’s software. In the main case the interpreter’s job is to interpret the print data and make it visual on a virtual image in the printer’s memory.
The interpreter sub-units are responsible for the conversion of a description of intended print instances into images that are to be marked on the media. A printer may have one or more interpreters. Each interpreter is generally implemented with software running on the System Controller sub-unit. The Interpreter Table has one entry per interpreter where the interpreters include both Page Description Language (PDL) Interpreters and Control Language Interpreters. Implementation of every object in this group is mandatory.
Before the advent of laser and inkjet technology, impact printers could only print standard, justified text with no variation in letter size or font style. Today, printers are able to process complex documents with embedded images, charts, and tables in multiple frames and in several languages, all in one print job. Such complexity must adhere to some format conventions. This is what spurred the development of the page description language (or PDL) — a specialized document formatting language specially made for computer communication with printers.
Over the years, printer manufacturers have developed their own proprietary languages to describe document formats. However, such proprietary languages are applied only to the printers that the manufacturers created themselves. If, for example, you were to send a print-ready file using a proprietary PDL to a professional press, there was no guarantee that your file would be compatible with the printer's machines. The issue of portability came into question.
Xerox® developed the Interpress™ protocol for their line of printers, but full adoption of the language by the rest of the printing industry was never realized. Two original developers of Interpress left Xerox and formed Adobe®, a software company catering mostly to electronic graphics and document professionals. At Adobe, they developed a widely-adopted PDL called PostScript™, which uses a markup language to describe text formatting and image information that could be processed by printers. At the same time, the Hewlett-Packard® Company developed the Printer Control Language™ (or PCL) for use in their ubiquitous Laser and inkjet printer lines. PostScript and PCL are widely adopted PDLs and are supported by most printer manufacturers (along with the printer's own proprietary languages, when available).
PDLs work on the same principle as computer programming languages. When a document is ready for printing, the PC or workstation takes the images, typographical information, and document layout, and uses them as objects that form instructions for the printer to process. The printer then translates those objects into rasters, a series of scanned lines that form an image of the document (called Raster Image Processing or RIP), and prints the output onto the page as one image, complete with text and any graphics included. This work-flow makes printing documents of any complexity uniform and standard, allowing for little or no variation in printing from one printer to the next. PDLs are designed to be portable to any format, and scalable to fit several paper sizes.
Choosing the right printer is a matter of determining what standards the various departments in your organization have adopted for their needs. Most departments use word processing and other productivity software that uses the PostScript language for outputting to printers. However, if your graphics department requires PCL or some proprietary form of printing, you must take that into consideration as well.
The two most popular printer languages are Postscript and Printer Control Language.
Postscript is a printer language that uses English phrases and programmatic constructions to describe the appearance of a printed page to the printer. This printer language was developed by Adobe in 1985. It introduced new features such as outline fonts and vector graphics. Printers now come from the factory with or can be loaded with Postscript support. Postscript is not restricted to printers. It can be used with any device that creates an image using dots such as screen displays, slide recorders, and image setters.
PCL (Printer Command Language) is an escape code language used to send commands to the printer for printing documents. Escape code language is so-called because the escape key begins the command sequence followed by a series of code numbers. Hewlett Packard originally devised PCL for dot matrix and inkjet printers. Since its introduction, it has become an industry standard. Other manufacturers who sell HP clones have copied it. Some of these clones are very good, but there are small differences in the way they print a page compared to real HP printers. In 1984, the original HP Laserjet printer was introduced using PCL. PCL helped change the appearance of low-cost printer documents from poor to exceptional quality.
Below is a list of all printer languages, which refers to the standards of the RFC 1759:
- PCL (Printer Control Language). Starting with PCL version 5, HP-GL/2 is included as part of the PCL language. PCL and HP-GL/2 are registered trademarks of Hewlett-Packard Company
- HPGL (Hewlett-Packard Graphics Language). HP-GL is a registered trademark of Hewlett-Packard Company
- PJL (Peripheral Job Language). Appears in the data stream between data intended for a page description language. Hewlett-Packard Co.
- PS (PostScript) Language (tm). Postscript - a trademark of Adobe Systems Incorporated which may be registered in certain jurisdictions
- PSPrinter. The PostScript Language used for control (with any PDLs). Adobe Systems Incorporated
- IPDS (Intelligent Printer Data Stream). Bi-directional print data stream for documents consisting of data objects (text, image, graphics, bar codes), resources (fonts, overlays) and page, form and finishing instructions. Facilitates system level device control, document tracking and error recovery throughout the print process. Pennant Systems, IBM.
- PPDS (Personal Printer Data Stream). Originally called IBM ASCII, the name was changed to PPDS when the Laser Printer was introduced in 1989. Lexmark International, Inc.
- EscapeP.
- Epson.
- DDIF (Digital Document Interchange Format). Digital Equipment Corp., Maynard MA.
- Interpress, ISO6429. ISO 6429. Control functions for Coded Character Sets (has ASCII control characters, plus additional controls for character imaging devices.) ISO Standard, Geneva, Switzerland
- LineData (line-data). Lines of data as separate ASCII or EBCDIC records and containing no control functions (no CR, LF, HT, FF, etc.). For use with traditional line printers. May use CR and/or LF to delimit lines, instead of records. See ISO 10175 Document Printing Application (DPA) ISO standard, Geneva, Switzerland
- MODCA (Mixed Object Document Content Architecture) Definitions that allow the composition, interchange, and presentation of final form documents as a collection of data objects (text, image, graphics, bar codes), resources (fonts, overlays) and page, form and finishing instructions. Pennant Systems, IBM
- REGIS (Remote Graphics Instruction Set), Digital Equipment Corp., Maynard MA.
- SCS- SNA Character String Bi-directional print data stream for SNA LU-1 mode of communications, IBM
- SPDL- ISO 10180 Standard Page Description Language ISO Standard.
- TEK4014.
- PDS.
- IGP.
- CodeV - Magnum Code-V, Image and printer control language used to control impact/dot-matrix printers. QMS, Inc., Mobile AL
- DSCDSE (DSC-DSE). Data Stream Compatible and Emulation Bi-directional print data stream for non-SNA (DSC) and SNA LU-3 3270 controller (DSE) communications. IBM
- WPS (Windows Printing System). Resource based command/data stream used by Microsoft At Work Peripherals. Developed by the Microsoft Corporation
- LN03. Early DEC-PPL3. Digital Equipment Corp.
- CCITT.
- QUIC (Quality Information Code), Page Description Language for laser printers. Included graphics, printer control capability and emulation of other well-known printer. QMS, Inc.
- CPAP (Common Printer Access Protocol) Digital Equipment Corp.
- DecPPL (Digital ANSI-Compliant Printing Protocol). Digital Equipment Corp.
- SimpleText - simple-text: character coded data, including NUL, CR, LF, HT, and FF control characters. See ISO 10175 Document Printing Application (DPA) ISO standard, Geneva, Switzerland
- NPAP (Network Printer Alliance Protocol) IEEE 1284.1
- DOC (Document Option Commands). Appears in the data stream between data intended for a page description. QMS, Inc.
- imPress. Page description language originally developed for the ImageServer line of systems. A binary language providing representations for text, simple graphics (rules, lines, conic sections), and some large forms (simple bit-map and CCITT group 3/4 encoded). The language was intended to be sent over an 8-bit channel and supported early document preparation languages (e.g. TeX and TROFF). QMS, Inc.
- Pinwriter. 24 wire dot matrix printer for USA, Europe, and Asia except Japan. More widely used in Germany, and some Asian countries than in US. NEC
- NPDL. Page printer for Japanese market. NEC
- NEC201PL. Serial printer language used in the Japanese market. NEC
- Automatic (Automatic PDL sensing). Automatic sensing of the interpreter language family by the printer examining the document content. Which actual interpreter language families are sensed depends on the printer implementation
- Pages. Page printer Advanced Graphic Escape Set. IBM Japan
- LIPS (LBP Image Processing System)
- TIFF (Tagged Image File Format). Aldus
- Diagnostic. A hex dump of the input to the interpreter
- CaPSL (Canon Print Systems Language)
- EXCL (Extended Command Language). Talaris Systems Inc.
- LCDS (Line Conditioned Data Stream). Xerox Corporation
- XES (Xerox Escape Sequences). Xerox Corporation
For more information see RFC 1759 (http://www.ietf.org/rfc.html)
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Last Updated ( Friday, 15 February 2008 )
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