PDF

Developed by Adobe Systems in 1994, the Portable Document Format (PDF) was and remains, by virtue of continuous advances, the worldwide standard for electronic data exchange. It was the first platform-independent exchange format for electronic documents and its many benefits put it front and center in nearly all market segments. Numerous special versions have emerged over the years that address the special requirements of specific industries and areas of application.

The Portable Document Format (PDF) is a platform-independent document format developed in the 1990s with the following aims:

• Exchange and display of electronic documents
• Graphic display of text and images independent of the resolution
• Optimization of documents for (web) display
• Interactive functions

PDF is derived from PostScript, although it is not a programming language, but a file format. It describes the pages of the document using objects (Boolean, numeric, string, name, array, dictionary, stream, the null object, and indirect objects) and the associated structure information. Interactive elements such as forms, bookmarks, sound objects, and thumbnails are available for use in electronic documents. To optimize the display on output devices with small screens (PDAs, mobile phones, smart phones, etc.), markup tagging (similar to HTML tags) can be integrated into a PDF. Markup enables page content to be wrapped, although the layout consistency is limited. It also makes it easy to convert the content into other formats, e.g. suitable for screen readers for blind users (accessibility).

PDF files describe the generated layout in a form largely true to the original and independent of printers and previous settings - one of the main differences in comparison to descriptive and markup languages such as SGML and HTML with respect to high layout consistency.

Main benefits of PDF documents are:

• Portability: PDF is platform-independent which means that a PDF document produced using e.g. a Windows application can be processed on a UNIX server and displayed on a Mac computer.
• Extra functions: The PDF format is based on the PostScript page descriptive language, and also provides direct access to pages and features for encryption, compression, interactive navigation and much more.
• Industrial standard: PDF has developed into an internationally recognized ISO standard for the electronic exchange of documents. PDF is also the most widely used format for the production of first prints in digital pre-press stages.
• Viewer/Reader: One of the main reasons for the high acceptance of the format is that complimentary display programs (viewer/reader) are available for all common platforms. This means that the content of a PDF file can be viewed using any hardware or software architecture with no graphical differences.

Due to the high acceptance of PDF as a document format, different PDF specifications have been developed for specific areas of document production and processing.

 

PDF/X (PDF for Exchange)

PDF/X (PDF for Exchange) was the first ISO standard for PDF and grew out of the very special requirements of the graphics and print industry. The standard was published in 2001 and regulates the transmission of print templates. It has been continually developed since then. In digital prepress, PDF/X is the most widely used format today.

Special features:

• Contains all data for fonts, graphics and print-out in high resolution
• Fully embedded fonts
• Storage of color profiles – precise definition of color management
• Current release: PDF-X5.

 

PDF/A (PDF for Archive)

PDF/A (PDF for Archive) for compact, long-term electronic archiving, an ISO standard since 2005. This standard was developed to meet the need to archive large numbers of documents with the ability to display them countless years later in the same quality as the day they were generated (with all the stored fonts, colors, logos, graphics, etc.) Many properties of PDF/A originated in PDF/X, such as correct embedding of fonts and colors.

Special features:

• Font subsetting as a means of keeping the PDF file compact
• Embedding of digital signatures
• Exact definition and storage of color profiles
• Encryption and locking (password protection) are prohibited
• No context-dependent and dynamic functions that could change the content and layout (barcodes, audio/video data)
• PDF/A-1a: Guarantees that the text content is extractable and the logical structure of the document as well as the natural reading process of the integrated text material remains the same
• PDF/A-1b: Guarantees that text and other page content are clearly reproduced; however does not guarantee that either is understandable and readable
• PDF/A-2: Standard pending certification with new enhancements for merging several output files into one PDF/A container and Unicode capability.

 

PDF/E (PDF for Engineering)

Standard format for technical documents from engineering, architecture and geoinformation. Adopted in 2008, this standard may eventually be integrated into PDF/A as a special version of the PDF archiving standard.

Special features:

• Display and interactive processing of 3D graphics and models
• Exchange of plans, drawings and other construction documents

 

PDF/VT (PDF for Variable Transaction Output)

This format allows incorporating variable data into the PDF, guaranteeing a secure end-to-end process. The international standard, published by ISO in August 2010, has many advantages over previous formats for printing variable data, especially maximum interoperability. In PDF/VT, the well-known assets of PDF are combined with several special PDF/X functions and are now available for the world of personalized printing. This includes long-term archiving, since PDF/VT can be seamlessly converted into PDF/A format.

PDF/VT was developed because more and more companies are delivering their printed files in PDF format, which is not as practical as AFP for large volumes of output (see AFP Glossary). The development of PDF/VT also advances the convergence of offset print files and variable digital data printing.  Experts assume that the PDF/VT and AFP will initially enjoy equal status on the market.

 

PDF/UA (PDF for Universal Accessibility)

This format allows to create and display documents that are also accessible to users with impaired sight or motor skills. The objective of the yet-to-be-established ISO standard is to define how PDF documents and the information elements they contain (graphics, text, multimedia, form fields) must be made accessible to this segment of the population (freedom from barriers).

Special features:

• Defines the sequence and language in which the text must be read
• Takes into account/ignores delimiters
• Tagging principle: what text passages and blocks belong together? What should not be read (e.g., page numbers, headers/footers, comments, source citations)?
• Storage of document structure, reading direction, and pronunciation.

 

PDF/H (PDF for Healthcare)

This format was developed with the support of the Committee on Healthcare Informatics of the American Society for Testing and Materials (ASTM). It is designed for the standardized exchange of patient data in healthcare. The idea underlying the format was to create an electronic "container" using the advantages and functions of PDF for archiving and data exchange between all the participants: clinics, hospitals, patients, private physicians, and insurance companies.

PDF/H can save the following data:

• Clinical reports
• Laboratory reports
• Forms
• Image data
• Photographs
• X-ray and CT images
• ECG and EEG data

Its platform-independence and sophisticated functions for embedding various types of resources and data make PDF an excellent format for long-term storage and display of important medical data that is true to the original.

 

PDF Conversion Directions

e.g.
PDF to AFP
PDF to IPDS
PDF to PCL
PDF to PostScript
PDF to XML

Find all PDF conversion directions in the Compart Matrix (PDF)