Typesetting
From Wikipedia, the free encyclopedia
Typesetting involves the presentation of textual material in graphic form on paper or some other medium. Before the advent of desktop publishing, typesetting of printed material was produced in print shops by compositors or typesetters working by hand, and later with machines.
The general principle of typesetting remains the same: the composition of glyphs into lines to form body matter, headings, captions and other pieces of text to make up a page image, and the printing or transfer of the page image onto paper and other media. The two disciplines are closely related. For example, in letterpress printing, ink spreads under the pressure of the press, and typesetters take this dynamic factor into account to achieve clean and legible results.
Contents |
[edit] Letterpress era
During the letterpress era, moveable type was composited by hand for each page. Cast metal sorts were composited into words and lines of text and tightly bound together to make up a page image called a forme, with all letter faces exactly the same height to form an even surface of type. The forme was mounted in a press, inked, and an impression made on paper.
The diagram at right illustrates a cast metal sort: a face, b body or shank, c point size, 1 shoulder, 2 nick, 3 groove, 4 foot. Wooden printing sorts were in use for centuries in combination with metal type.
Copies of formes were cast when anticipating subsequent printings of a text, freeing the costly type for other work. In this process, called stereotyping, the entire forme is pressed into a fine matrix such as plaster of Paris or papier mâché to create a negative, from which the stereotype forme was cast of alloy.
Hand compositing was rendered obsolete by continuous casting or hot-metal typesetting machines such as the Linotype machine and Monotype at the end of the 19th century. The Linotype, invented by Ottmar Mergenthaler, enabled one machine operator to do the work of ten hand compositors. Later advances such as the typewriter and computer would push the state of the art even farther ahead. Still, hand-compositing and letterpress printing did not fall completely out of use, and since the introduction of digital typesetting, it has seen a revival as an artisanal pursuit. However, it is a very small niche within the larger typesetting market.
[edit] Phototypesetting
Phototypesetting systems first appeared in the early 1960s and rapidly displaced continuous casting machines. These devices consisted of glass disks (one per font) that spun in front of a light source which selectively exposed characters onto light-sensitive paper. Originally they were driven by pre-punched paper tapes. Later they were hooked up to computer front ends.
One of the earliest electronic photocomposition systems was introduced by Fairchild Semiconductor. The typesetter typed a line of text on a Fairchild keyboard that had no display. To verify correct content of the line it was typed a second time. If the two lines were identical a bell rang and the machine produced a punched paper tape corresponding to the text. With the completion of a block of lines the typesetter fed the corresponding paper tapes into a phototypesetting device which mechanically set type outlines printed on glass sheets into place for exposure onto a negative film. Photosensitive paper was exposed to light through the negative film, resulting in a column of black type on white paper, or a galley. The galley was then cut up and used to create a mechanical drawing or paste up of a whole page. A large film negative of the page is shot and used to make a plates for offset printing.
[edit] Digital era
The next generation of phototypesetting machines to emerge were those that generated characters on a Cathode ray tube. Typical of the type was the Autologic APS5. These machines were the mainstay of phototypesetting for much of the 1970s and 1980s. Such machines could be 'driven online' by a computer front-end system or take their data from magnetic tape. Type fonts were stored digitally on conventional magnetic disk drives.
Computers excel at automatically typesetting documents. Character-by-character computer-aided phototypesetting was in turn rapidly rendered obsolete in the 1980s by fully digital systems employing a raster image processor to render an entire page to a single high-resolution digital image, now known as imagesetting.
The first commercially successful laser imagesetter, able to make use of a raster image processor was the Monotype Lasercomp. ECRM, Compugraphic (later purchased by Agfa) and others rapidly followed suit with machines of their own.
Early minicomputer-based typesetting software introduced in the 1970s and early 1980s such as Datalogics Pager, Penta, Miles 33, Xyvision, troff from Bell Labs, and IBM's Script product with CRT terminals, replaced these electro-mechanical devices and used text markup languages to describe type and other page formatting information. The descendants of these text markup languages include SGML, XML and HTML.
The minicomputer systems output columns of text on film for paste-up and eventually produced entire pages and signatures of 4, 8, 16 or more pages using imposition software on devices such as the Israeli-made Scitex Dolev. The data stream used by these systems to drive page layout on printers and imagesetters led to the development of printer control languages such as Adobe Systems PostScript and Hewlett-Packard's HP PCL.
Before the 1980s, practically all typesetting for publishers and advertisers was performed by specialist typesetting companies. These companies performed keyboarding, editing and production of paper or film output, and formed a large component of the graphic arts industry. In the United States these companies were located in rural Pennsylvania, New England or the Midwest where labor was cheap, but within a few hours' travel time of the major publishing centers.
In 1985, desktop publishing became available, starting with the Apple Macintosh, Adobe PageMaker (and later QuarkXPress) and PostScript. Improvements in software and hardware, and rapidly-lowering costs, popularized desktop publishing and enabled very fine control of typeset results much less expensively than the minicomputer dedicated systems. At the same time, word processing systems such as Wang and WordPerfect revolutionized office documents. They did not, however, have the typographic ability or flexibility required for complicated book layout, graphics, mathematics, or advanced hyphenation and justification rules (H and J).
By the year 2000 this industry segment had shrunk because publishers were now capable of integrating typesetting and graphic design on their own in-house computers. Many found that the cost of maintaining high standards of typographic design and technical skill made it more economical to out-source to freelancers and graphic design specialists.
The availability of cheap, or free, fonts made the conversion to do-it-yourself easier but also opened up a gap between skilled designers and amateurs. The advent of PostScript, supplemented by the PDF file format, provided a universal method of proofing designs and layouts, readable on major computer and operating systems.
[edit] SGML and XML systems
The arrival of SGML/XML as the document model made other typesetting engines popular. Such engines include Datalogics Pager, Penta, Miles 33, OASYS, Xyvision's XML Professional Publisher (XPP), FrameMaker, Arbortext, YesLogic's Prince, QuarkXPress and Adobe InDesign. These products allow users to program their typesetting process around the SGML/XML with the help of scripting languages. Some of them, such as UltraXML, provide attractive WYSIWYG interfaces with support for XML standards and Unicode to attract a wider spectrum of users.
[edit] Troff and Successors
During the mid-1970s Joseph Ossanna, working at Bell Laboratories, wrote the troff typesetting program to drive a Wang C/A/T phototypesetter owned by the Labs; it was later enhanced by Brian Kernighan to support output to different equipment such as laser printers and the like. While its use has fallen off, it is still included with a number of Unix and Unix-like systems and has been used to typeset a number of high-profile technical and computer books. Some versions, as well as a GNU work-alike called groff, are now open source.
[edit] TeX and LaTeX
The TeX system, developed by Donald E. Knuth at the end of 70s, is another widespread and powerful automated typesetting system that has set high standards, especially for typesetting mathematics. TeX is considered fairly difficult to learn on its own, and deals more with appearance than structure. The LaTeX macro package written by Leslie Lamport at the beginning of 80s, offered a simpler interface, and an easier way to systematically encode the structure of a document. LaTeX markup is very widely used in academic circles for published papers and even books. Standard TeX does not provide a WYSIWYG interface, though there are programs such as LyX and Scientific Workplace that provide one. Another WYSIWYG editor very much inspired by TeX is TeXmacs.
[edit] Further reading
- Dingbat
- Hot metal typesetting
- Justification (typesetting)
- Ligature (typography)
- Printing
- Printing press
- Sort (typesetting)
- Typeface
- Typography
- Widows and orphans
- Strut (typesetting)
- Composing stick
|
|||||||||||
