A machine that generates output for the printing process, which is either a film-based paper that is photographed or the actual film for making the printing plates. Input comes from the keyboard, or via disk, tape or modem. Earlier machines handled only text and were called "phototypesetters." Most imagesetters today support the PostScript language.|
Modern imagesetters use lasers to generate the image directly onto the film. Older machines passed light through a spinning font photomask, then through lenses that created the point size and onto film. Others created images on CRTs and exposed the film.
The typesetter was originally the only machine that could handle multiple fonts and text composition such as kerning. Today, desktop laser printers are used for many typesetting jobs and are quickly advancing in resolution, although the 1,270 and 2,540 dpi resolutions of the imagesetter combined with the high-quality of film still provide the finest printing for photographs and halftones. See CTP.
Imagesetters increasingly generate output without using the wet chemical process of traditional film. This ColorSpan PressMate-FS uses a dry, chemical-free process that can produce 2,400 dpi positive or negative film separations direct from a PC or Mac. Plates are made directly from the film. (Image courtesy of ColorSpan Corporation.)