A “printers pair” (or printer’s spread, imposed spread) is a left and right hand page displayed together for the sake of further imposition and printing. Once many printers pairs are printed together and bound correctly, the artwork will appear with the correct page sequence once bound. This is different from a reader’s spread which displays a left and right hand page but the pages read in correct sequence on-screen only.

In my line of work, printers pairs are ultimately made by sending single page PDFs to the dedicated imposition software on the RIP. Without going into great detail about imposition in this post, have a look at Wikipedia’s definition of the term.

For others, preparing printers pairs can in InDesign can be useful. For example, a copy shop with an A3+ copier may use a feature in older versions of InDesign called Print Booklet, which allows saddle-stitched artwork to be created as readers spreads for direct output to a copier without the need for dedicated imposition software or RIPs.

However…

Imposition is best left to the experts as only they will know how the artwork should be imposed. This is covered more in the earlier post: Don’t impose your artwork on me!

Nevertheless…

If you have received a PDF prepared as printers pairs and need to break them back into singles, I have prepared a method which works quite well in breaking them back into single pages. You will need two javascripts to do this:

• MultiPageImporter2.5.jsx by Scott Zanelli (updated by Jim Birkenseer); and
• Adjustlayout.jsx – a script which ships with InDesign.

The example shown here will be to transform a 16pp A4 document prepared as 8 x A3 printers pairs back into A4 single pages, but the principles will work with other sizes.

1. Create a new InDesign Document measuring the finished trim size. This document has sixteen pages and facing pages are turned off.
   
2. A new document is created. Double-click the MultiPageImporter2.5.jsx script from the Scripts Panel. Once a new dialog appears prompting for the PDF file to insert. Navigate to the PDF and click OK.
3. A new dialog box will appear. In the Page Selection area, import the entire pdf starting on page 1; in the Positioning Options area, pages should be positioned from the centre, with 0mm page offsets. In the Sizing Options area, leave the scale at 100% scale. In the Placement Options area, crop to Media (the 3 checkboxes are up to the user) then Click OK.
   
4. The script will now run and place the PDFs into each page. Once the script has run, double-click the MultiPageImporter2.5.jsx script from the Scripts Panel again and once a new dialog appears prompting for the PDF file to insert. Navigate to the PDF and click OK. This time, make sure that the Reverse Page Order checkbox is ON and that Start Placing on Doc Page is page 9 (or one more than the total amount of pages in the PDF to split. Because this example is 16xA4 pages, there are 8xA3 pages, so in the example we start placing from page 9).
   
5. The script will now add the other half of the pages to the document and the pages should look something like this:
   
6. To get the pages into their correct position, go to the scripts palette and double click the script AdjustLayout.jsx. From here, adjust the pages so that the odd pages move half of the finished trim distance to the left (in this example that is -105mm, or as displayed in points in the example below, -297.638pt) and move the even pages half of the finished trim distance to the right. Note that this script uses points as the default measurement so if measuring in millimetres, make sure to type mm at the end of the measurement. The script will also convert the mm measurement to points once the cursor is moved from one field to another.
   
7. The script will now run and the pages should end up looking like this:
   Now that the pages are in the correct order, single page PDFs can be generated from InDesign for imposition.