The magazine of the Melbourne PC User Group Adobe Portable Document Format Major Keary |
Adobe's Portable Document Format (PDF) was introduced in 1993. Since then the Acrobat Reader has become ubiquitous - 200 million copies have been distributed world-wide - and PDF has been adopted as the de facto standard for electronic exchange of documents. It is also playing an increasingly important role in the print industry.
Adobe publishes the PDF specification in full technical detail for the benefit of developers who write "programs that read or generate PDF files, and for any professional working with PDF in business, prepress, graphic design, or other applications". The text is well supported with illustrative code, diagrams, and other tabulated data.
There are many non-Adobe products that can be used to produce PDF files (a dozen are listed on the tucows website) but most rely on Adobe's Acrobat Reader for viewing and printing. Non-Adobe applications that can be used to create - and in some cases read - PDF files must comply substantially with the PDF specification, which has been thoroughly documented by Adobe in the PDF Reference published by Addison-Welsey. Now in its third edition the Reference covers version 1.4, which is used in Acrobat 5. There are a number of new features, such as a new transparent imaging model and support for disabled users.
On the issue of accessibility support, the PDF specification includes facilities for visually impaired people who use screen readers to read documents aloud in a specified natural language; there is also provision for "textual descriptions for images or other items that do not translate naturally into text"; and version 1.4 can specify "the expansion of abbreviations or acronyms".
To implement those facilities requires a logical structure framework - introduced in v.1.3 - to be applied to the file. New in v.1.4 is tagged PDF, which defines "a set of structure types and attributes that allow page content (text, graphics, and images) to be extracted and reused for other purposes".
A number of other significant features have been introduced. Among those is the ability to import content from one PDF file into another; it may not be as flexible as one would like, but is a significant improvement on earlier versions.
Also introduced are enhancements to the interactive forms facility, upgraded viewer references, and improved encryption.
A highly technical text that presents all the information required by developers and software engineers to create stand-alone PDF applications, or embed PDF capabilities into other applications. In spite of its technical nature, the text is a model of clarity.
| Adobe Systems: PDF
Reference 3/e ISBN 0-201-75839-3 Published by Addison-Wesley, 944 pp. + CD, RRP $116.95 incl. GST |
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Reprinted from the September 2002 issue of PC Update, the magazine of Melbourne PC User Group, Australia
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