Monthly Archives: November 2013

PDF with very large page sizes

Most PDF files are created from source material that is either generated in some form of Office software, like MS Office Word or Powerpoint, OpenOffice etc, or from a publishing system like Quark or InDesign. In almost all instances the underlying page size or sizes used are A4/US letter or smaller, in a fixed orientation (portrait or landscape). However, for files that are generated from graphics (drawing/design) packages or engineering systems, or from large-format old documents that have been scanned in, there is an often an issue with the page size.

In general, electronic display of documents on tablet devices is best handled with a relatively small underlying page size and/or the use of larger fonts. A5/half US Letter gives excellent results on most devices, and conversely, larger than A4/US Letter tends to result in files that cannot be read without zooming in on the page. Typically zooming-in makes reading the whole document/seeing the whole picture difficult and if printing is permitted (which in many cases it is not of course) then issues arise with print scaling which may prove unsurmountable. Zooming into very large pages (which is effectively an image zoom operation) is computationally demanding and may be slow or even impossible after a specific level of zooming on some devices (i.e. the software restricts the total zoom level owing to memory management or processing issues on the device).

There are a couple of solutions to these problems:

Scaling the source material: if the source material is a scanned image or a graphic, then the output PDF file created can be scaled to a selected underlying page size, e.g. A4/US Letter. This scaling can take place as part of the PDF file creation or, for image data, scaling can be carried out in the source application or image editor prior to printing to PDF. Obviously a scaled image may well be unreadable at the reduced size and/or may lose resolution in the scaling process, so a second option is worth considering.

Tiling the source material: instead of creating a single very large page a series of standard-sized pages can be created, with the large page spread across multiple standard-sized pages. This can be done in two ways – the source program may allow the output page size to be specified (e.g. via a Page Setup option) prior to creating the PDF file, so they resulting PDF is spread across several pages. Alternatively, and in many cases as a preferable option, the PDF can be generated with large page sizes and then the pages can be tiled using the tiling facility in Adobe Acrobat, as shown below. Typically the tiling process generates output for printing on a standard printer – i.e. one that handles pages up to A4/US Letter in size, which is the most common use for this facility, but you can specify the output as a PDF, and then a new PDF with tiled pages will be generated. An example can be seen: here…. Note that in this example I have specified a 10mm overlap which tells Adobe Acrobat to overlap the output pages and to include trim marks in the margins so it is easy to see how the pages fit together, and if printing is permitted, how to print and assemble a full-sized page from the tiled elements.

How to add bookmarks (outlines, contents, navigation trees) to a PDF file

This brief article is about how to add bookmarks to create a navigation tree in a fairly ‘standard’ PDF. Such navigation facilities are of increasing important for use with mobile devices for speedy access to information, especially for large documents (100s or 1000s of pages).

The term “bookmarks” is slightly misleading, because when you add these to an existing PDF it typically will do two things: (i) mark the page selected or location selected as having a bookmark; and (ii) provide a convenient means of locating that bookmark quickly. Thus step (ii) is a form of interactive contents page, easily accessible at all times.

The usual facility provided for step (ii) is for a navigation tree to be created – on desktops and laptops this is displayed as a tree structure to one side of the document display… on a Mac computer (e.g. using Preview or Javelin) this is often referred to as the document “Outline”. On mobile devices, including tablets, there is not enough space to display a separate navigation tree, so the better PDF readers display the tree via a button (e.g. a Contents button that displays each level of the tree in a scrollable window). In addition, many such readers also provide for user-created bookmarks, which are accessed in a variety of ways. However, here we just focus on pre-generated bookmarks and navigation trees.

How to create a pre-generated navigation tree: if you have a PDF already, with no navigation tree, you can add a navigation tree using Adobe Acrobat, Infix or a number of other PDF editing software packages. Almost all are provided as commercial offerings, but the highly rated freeware program available via sourceforge at:

http://sourceforge.net/projects/jpdfbookmarks/

provides an alternative with all the functionality you need. The advantage of adding a navigation tree to an existing PDF is that the process is clear and simple, and ideal if you do not have a source program that will generate the tree for you. However, a better approach exists if you do have the source material. Some software packages, such as InDesign and Microsft Word, have a facility to Export to PDF or Save as PDF. For Word (Office 2007 and later) and InDesign this process can generate a table of contents and/or navigation tree, with internal hyperlinks so that the pages are accessed rapidly. In the case of Word it uses heading styles, so a well structured document that makes uses of these styles to structure the document will produce a suitable output file. Earlier versions of Word do not offer this facility so an add-on program like PDF Creator Plus (http://www.peernet.com/conversion-software/create-pdf/) will do the trick, but it may take some time to complete (depending on the document size and complexity). Currently the excellent and fast PDF creation facility in OpenOffice does not create these elements of a structured PDF, so post-processing is necessary if you use this option or a pure PDF Writer (virtual printer) to create your PDF files.

Having created a PDF with bookmarks/navigation, the next step is to test it across multiple platforms with the software you expect to be used to display it, if it is to be distributed widely. PDFs do not have a single agreed standard format, and in many cases features supported by Adobe, for example, simply do not work on most other readers. Common problems include: no navigation tree is displayed at all on some platforms; some of the characters used in the tree are displayed incorrectly; some links do not work; some links always send you to the first page. In general creating links that do not contain special or unusual characters, and links that point to pages rather than named destinations, are more likely to work on most software and most platforms.

and from an earlier article we wrote on this topic, you may find the following useful:

PDF files often contain internal and external links that have been created in the source document (e.g. Word, InDesign etc) or have been added subsequently using a PDF Editor. However, many PDF files do not contain a navigation tree, and this is almost essential for fast navigation of the documents especially on mobile devices such as iPADs and Androids. If your PDF file does not have a navigation tree there are two main methods for adding one:

(1) there may be a facility in the source program (e.g. Microsoft Word, InDesign etc) to include a manually or automatically generated navigation tree; or

(2) a navigation tree can be added to the PDF itself, subsequently, by editing the PDF using software such as Adobe Acrobat or Infix.

In the latter case the PDF is opened in Adobe Acrobat or a similar PDF editor and the Bookmarks tab is made visible. Then one simply navigates to the first page to be included in the tree, e.g. the Cover, then right clicking on that page adds the first entry into the tree and you enter the text required (e.g. Cover). This process continues, with nested entries permitted, until the entire tree has been constructed and the document is then saved. This procedure works, but can be very time consuming, especially with large and complex documents.

In the former case the document structure is used to create a navigation tree automatically, in much the same way that a contents page is generated. In the case of documents created using Microsoft Word 2007 or later, there is a SAVE AS PDF function that may be used. The standard options do not include creation of a navigation tree from the Heading styles that have been employed, but by clicking on the Options.. button the screen shown below is displayed. By ensuring that Create Bookmarks box is ticked a navigation tree will be generated automatically, and this will mirror the information provided in the Contents page (if one is included). Other document creation software has similar functionality (but not all!).

If you have any queries about PDF navigation and are interested in our secure PDF publishing solutions, please just email us (info@drumlinsecurity.com) and we will get back to you with our suggestions.