Prepress is the term used in the printing and publishing industries for the processes and procedures that occur between the creation of a print layout and the final printing. The prepress procedure includes the manufacture of a printing plate, image carrier or form, ready for mounting on a printing press, as well as the adjustment of images and texts or the creation of a high-quality print file. In today's prepress shop, the form of delivery from the customer is usually electronic, either a PDF or application files created from programs such as Scribus, Adobe InDesign, Adobe Illustrator, or QuarkXPress.
The following items have each been considered part of prepress at one time or another:
In most modern publishing environments, the tasks related to content generation and refinement are carried out separately from other prepress tasks, and are commonly characterized as part of graphic design. Some companies combine the roles of graphic design and prepress production into desktop publishing (DTP).
The set of procedures used in any particular prepress environment is known as a workflow. Workflows vary, depending on the printing process (e.g. letterpress, offset, digital printing, screen printing), the final product (books, newspapers, product packaging), and the implementation of specific prepress technologies. For example, it is not uncommon to use a computer and image-setter to generate film which is then stripped and used to expose the plate in a vacuum frame; this workflow is hybrid because separation and halftoning are carried out via digital processes while the exposure of the plate is an analog one. That demonstrates that the borders around the prepress are very fluid. Furthermore, – depending on the printing method and the print product – the elements of the prepress of a graphic print production can differ from case to case. This circumstance requires a management of the workflow. It is necessary to manage the responsibility for each part of the workflow. That can mean that employees, who are actually responsible for other parts of the production (e.g. layout), have to attend to parts of the prepress.
During the 1980s and 1990s, computer-aided prepress techniques began to supplant the traditional dark room and light table processes, and by the early 2000s the word prepress became, in some ways, synonymous with digital pre-press. Immediately before the mainstream introduction of computers to the process, much of the industry was using large format cameras to make emulsion-based (film) copies of text and images. This film was then assembled (planning (UK) or stripping) and used to expose another layer of emulsion on a plate, thus copying images from one emulsion to another. This method is still used; however, as digital pre-press technology has become less cost intensive, more efficient and reliable, and as the knowledge and skill required to use the new hardware and especially software have become more widespread within the labor force, digital automation has been introduced to almost every part of the process. Some topics related to digital but not analog prepress include preflighting (verifying the presence, quality and format of each digital component), color management, and RIPping.
PDF workflows also became predominant. Vendors of Prepress systems, in addition to the offset printing industry, embraced a subset of the PDF format referred to as PDF/X1-a. This industry specific subset is one version of the PDF/X (PDF for eXchange) set of standards.
In more recent years, prepress software has been developed which is designed to find as many efficiencies in prepress workflow as possible. These tools are accessed online, and allow different workers to work on one project at the same time, often from different locations. Key functionality automates common steps to reduce errors, reinforce quality standards and speed up production. Examples include automatically re-folioing pages, digital dummies for soft proofs, live linking with Adobe InDesign and pre-flight checking. These tools revolve around a Flatplan and are used in all sorts of prepress including book, magazine and catalog production.