Tuesday, August 1, 2006
Originally written for acrobatusers.com.
To optimize HTML, you need to really know your way around the HyperText Markup Language. Optimizing PDF with usability features that will satisfy the vast majority of users is much easier.
The following guidelines for optimizing PDF documents are not a panacea for bad or thoughtless design. If you insist on multi-column pages, exotic text runs or radical graphics, for example, then be prepared to put in some extra work to ensure they are structured correctly.
Tips: Designing PDFs with usability in mind
- If possible, use an application that supports PDF tags, such as Microsoft Word or Excel, Adobe InDesign or FrameMaker or OpenOffice - and use consistent styles.
- Understand how adding PDF bookmarks may be built into the layout process.
- Decide on the likely principal usage of your document (printed or online), and format the page accordingly
- Slides are usually best as landscape pages.
- Simpler layouts, with fewer sidebars and boxes, are best.
- Don't create a heavy dark background behind white text if you want people to print it.
- Avoid two- (or more) column text unless absolutely necessary; and if you do, structure and tag the file to ensure the correct logical order is indicated.
- Avoid having multiple articles start on one page and land on non-sequential pages (like a newspaper) — UNLESS you are prepared to build in the necessary links and/or article threads.
Tips: Improving existing PDF usability
- Ensure that each PDF file's Document Information fields are filled in, especially Title. Search engines display this information in their search-results!
- Any PDF longer than a few pages should have navigational bookmarks to allow the user to jump to any subsection. Bookmarks may be added in Acrobat (Control-B), through the "Make Adobe PDF" command in Microsoft Office and via a wide variety of third-party Acrobat plug-ins. Auto-generated bookmarks should be checked before posting the file — the automation can produce some boo-boos.
- If a PDF includes bookmarks, set the file's Initial View to show "Bookmarks Panel and Page." Otherwise users will have no idea that bookmarks are available for this file.
- If a landscape-oriented (horizontal) PDF is meant primarily to be read online rather than printed, set the file's Initial View is to "Fit Page."
- Include active Web links in your PDF files to help users return to your website. If you don't have an obvious place for such a link, you can add a non-printing button that links back to your site. You can also use a bookmark as a Web link.
- In the Acrobat Preferences> General settings, enable the "Optimize for Fast Web View" option. (Exception: Files containing form fields should NOT be optimized for Fast Web View.)
- Ensure that the server hosting the files supports Fast Web View. Most do automatically.
- Reduce the file size of PDF files as much as possible. PDF files are often unnecessarily "overweight," containing internal data that's not needed and that bloats the file's size. For example, high-resolution images and/or multiple embedded fonts may be required for best-quality printing, but not for low-end printers or for online display. Adjust Optimizer's compression options to reach a better balance between file size and document quality.
- In PDF Optimizer, another option is to set your PDF files to "Acrobat 5.0 compatibility," which can impact certain features when the PDF is viewed with an earlier version. For example, the colored or boldface bookmarks created with more recent versions of Acrobat are not supported in version 5.0.
- Always indicate a PDF file's size adjacent to the active link the on the linking page so users can make an informed decision before trying to download or view it.
- For optimal usability, add structural tags to your PDF files, then validate and correct the resulting structure. This will allow even multi-column PDF files to "Reflow" (Control-4) reliably, so users may change text size and scroll vertically through all the content on the page. These features are not easy, as yet, to manage in Acrobat, but for simpler documents, the automation works out well in most cases.
