Imposition is one of the fundamental steps in the prepress printing process. It consists of the arrangement of the printed product’s pages on the printer’s sheet, in order to obtain faster printing, simplify binding and reduce paper waste. Correct imposition minimizes printing time by maximizing the number of pages per impression, reducing cost of press time and materials. To achieve this, the printed sheet must be filled as fully as possible. Task The arrangement of pages on the printer’s sheet is affected by five different parameters: Format of the product: The size of the finished page determines how many pages can be printed on a single sheet. Number of pages of the printed product: The compositor must determine how many sheets are to be printed to create a finished book. Stitching/binding method: The compositor must understand how the sheets are placed to form the signatures that compose the finished book. Paper fiber direction: Many papers have a "grain," reflecting the alignment of the paper fibers. These fibers must run lengthwise along the fold, which influences the alignment, hence the position, of the pages on the printed sheet. Finishing and binding To understand how the pages are related to each other, an imposition dummy may be used. This is made by folding several sheets of paper in the way the press will print and fold the product. A little copy is then created, and this can help paginate the product. In the example above, a 16-page book is prepared for printing. There are eight pages on the front of the sheet, and the corresponding eight pages on the back. After printing, the paper is folded in half vertically (page two falls against page three). Then it is folded again horizontally (page four meets page five). A third fold completes this process (page nine meets page eight). The example below shows the final result prior to binding and trimming. Non-digital techniques Imposition has been a requirement since the earliest days of printing. When pages were set using movable type, pages were assembled in a metal frame called a chase, and locked into place using wedges called quoins. By the late twentieth century, most typesetting was onto photographic film. These sheets were combined manually on a light table, in a process called stripping. Skilled workers would spend many hours stripping pieces of film together in the correct sequence and orientation. The term stripping