Imposition

Putting Your Printed Pages in the Right Order

Imposition is the process of arranging the pages of a print job, like a book or a newspaper, into the right sequence so that several pages may be printed on the same sheet of paper, which is later trimmed and bound as a finished product.

Page Sequencing

Consider a 16-page booklet. A large commercial press can accommodate paper much larger than the size of a single booklet page, so the press will print several pages together on the same sheet, then fold and trim the result.

With a 16-page booklet, a typical commercial printer will print this job with one sheet of paper, printed double-sided. An automatic folder folds the pages, then a trimmer slices the folds, leaving a perfectly aligned booklet ready for stapling.

When the commercial printer does its job, though, it'll print the pages in a special sequence to support the folding-and-trimming part of the process:

  • The front side of the sheet consists of two rows of booklet pages. The top row contains booklet pages 5, 12, 9, and 8, with the top of the booklet page centered along the middle of the large paper sheet. The lower row contains booklet pages 4, 13, 16, and 1, again with the top of the booklet page aligned with the middle of the larger paper sheet. 
  • The back side will be structured similarly. The top row of booklet pages includes 7, 10, 11 and 6. The bottom row includes 2, 15, 14, and 3.

The two page numbers that are imposed side-by-side always add up to one more than the total number of pages in the booklet.

For example, in a 16-page booklet, all pairs of pages paired together add up to 17 (5+12, 2+15, etc.).

Printing Folios

folio is a four-page arrangement of paper. Although different commercial presses accept jobs of varying sizes, a standard convention is to size paper such that a "four up" approach—four pages per side per sheet of paper—results.

The folio standard is one reason some print-on-demand book developers require manuscripts with page counts evenly divisible by four.

Modern digital printing relies on the transmission of electronic files, usually in the Adobe Portable Document Format standard, as a print-ready solution for high-speed printing. Documents intended for commercial printing, like books and magazines and newspapers, are generally developed in a professional-grade layout program like Adobe InDesign or QuarkXPress. These applications offer specific export options to ensure that a complete document is exported in a way that allows the commercial press's control software to slot the correct page in the template.

Working with Commercial Printers

Different commercial printers support different sizes of rolled paper, so you cannot guarantee you'll know in advance how to structure the pages in your output file until you confirm details with the press's prepress department. In addition, these printers use control software of varying types and ages, so a file that one commercial press could support, another might not.

Imposition used to be a normal, and often manual, part of the publishing process. As digital printing becomes more mainstream and commercial-press software adapts to modern file types, it's increasingly common for the press itself to auto-impose the correct layout based on a normal export-to-PDF file, without additional intervention by the designer.

When in doubt, reach out to the prepress supervisor. You'll need to know the trim size—the size of a final page of output in your finished product—and the number of pages. The prepress team will advise as to specific imposition requirements.