(v13) Imposition

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

This chapter entails lower-level position support. For higher level support, see (v13) HqnImpose2 and simple imposition compatibility and (v13) Simple in-RIP imposition.

Imposition is the process of placing more than one page of a document onto the same output medium (typically a film or printing plate). The Harlequin RIP comes equipped with a procset (the HqnImpose2 procset) that makes many simple imposition tasks easier; this is described in (v13) Imposition features. The present chapter discusses the RIP extensions that it uses, and which may be useful for more complex jobs than the procset can handle.

Imposition facilities allow:

• Better utilization of large format output recorders without the need for an additional manual imposition stage
• Electronic preparation of layouts for plate-making, including effects such as bottling and shingling
• Better performance with some kinds of job (it is often more efficient to make maximum use of the fast-scan direction of output recorders by placing pages side-by-side; however, this requires more marks to be rendered in each horizontal section, so this depends on memory configuration, complexity of jobs, interaction of halftone screens and so on)
• Paper and film-saving (for drafts, perhaps), by reducing the size of the original pages and imposing them two-up or four-up on the output
• Production of a sheet of thumbnails, or loose proofs
• Adding annotation to pages (such as information about the job)

There are some limitations, however; the most important are:

• Unless there is some external software gathering up jobs for imposition, only pages from a single job can be imposed.
• Pages can only be imposed in the order they appear in the original job. (However, it is possible to omit pages completely.) This means that automatic gathering into folios for printing is difficult without some preprocessing, unless all the pages appear on one sheet.
• Because more graphic objects are being placed on each output page (the contents of two or more original pages), such output pages are more demanding than the individual original pages. This means that imposed pages may require more resources, such as memory and disk space; they are more likely to cause underrun on output devices which either do not prepare the whole page at once or cannot stop the medium. Given sufficient resources, however, imposed pages can increase efficiency.
• Pages cannot be overlapped.
  
  

Page imposition is different from putting more than one separation on the same output medium when separation is done automatically within the Harlequin RIP: this is dealt with in (v13) Color separation, especially in (v13) Using separation and imposition together. Pre-separated jobs, however, are no more than consecutive pages so far as the Harlequin RIP is concerned, so the comments in this chapter do apply to these jobs.