Chapter 9
Multipage Facilities

9.1 Inserting Blank Pages

Sometimes, for instance to get a printing arrangement right, it’s useful to be able to insert blank pages into a PDF file. Cpdf can add blank pages before a given page or pages, or after. The pages in question are specified by a range in the usual way:

The dimensions of the padded page are derived from the boxes (media box, crop box etc.) of the page after or before which the padding is to be applied.

The -pad-every n operation places a blank page after every n pages, excluding any last one. For example on a 9 page document this command adds a blank page after pages 3 and 6:

In all three of these operations, one may specify -pad-with providing a (usually one-page) PDF file to be used instead of a blank page. For example, a page saying “This page left intentionally blank”.

The -pad-multiple n operation adds blank pages so the document has a multiple of n pages. For example:

The -pad-multiple-before n operation adds the padding pages at the beginning of the file instead.

9.2 Redaction

Cpdf has basic redaction facilities to remove whole pages. We simply give the page range, and such pages will be emptied of content, and any annotations and page resources removed. The page dimensions remain the same.

If -process-struct-trees is added to the command, the document’s structure tree will be shorn of any parts which are marked as relating to the now-redacted pages.

9.3 Imposition

Imposition is the act of putting two or more pages of an input document onto each page of the output document. There are two operations provided by Cpdf:

• the -impose operation which, given a page size fits multiple pages into it; and

• the -impose-xy operation which, given an x and y value, builds an output page which fits x input pages horizontally and y input pages vertically.

The x value for -impose-xy may be set to zero to indicate an infinitely-wide page; the y value to indicate an infinitely-long one. In both cases, the pages in the input file are assumed to be of the same dimensions.

The following options may be used to modify the output:

• -impose-columns Lay the pages out in columns rather than rows.

• -impose-rtl Lay the pages out right-to-left.

• -impose-btt Lay the pages out bottom-to-top.

• -impose-margin <margin> Add a margin around the edge of the page of the given width. When using -impose-xy the page size increases; with -impose the pages are scaled.

• -impose-spacing <spacing> Add spacing between each row and column. When using -impose-xy the page size increases; with -impose the pages are scaled.

• -impose-linewidth <width> Add a border around each input page. With -impose the pages are scaled after the border is added, so you must account for this yourself.

To impose with rotated pages, for example to put two A4 portrait pages two-up on an A3 landscape page, rotate them prior to imposition.

Two other ways of putting multiple pages on a single page remain from earlier versions of Cpdf which lacked a general imposition operation. The -twoup-stack operation puts two logical pages on each physical page, rotating them 90 degrees to do so. The new mediabox is thus larger. The -twoup operation does the same, but scales the new sides down so that the media box is unchanged.

NB: For all imposition options, see also discussion of -fast in Section 1.13.

9.4 Chopping up pages

The -chop operation cuts up a page into multiple pages, according to the chosen grid, and those pages replace the originals in the PDF. It is a sort of de-imposition. For example:

The crop box is used if present; if not, the media box. By default, the pieces are arranged in the output file row by row, and from left to right on each row. To alter this, add one or more of -chop-columns, -chop-rtl (right to left), and -chop-btt (bottom to top).

As an alternative, pages can be chopped into two at a given position, horizontally with -chop-h or vertically with -chop-v:

To reverse the order of pages in the output, specify -chop-columns in addition.