Postscript and PDF as standards

PostScript, the page description language developed by the Californian company Adobe, has been used for the creation of graphic output on various devices for almost twenty years. PostScript support can be found as a so-called PostScript interpreter in  many devices, such as the laser printer in an office or the exposure machine that creates films for offset printing. Apart from that, each operating system contains drivers for the output on a postscript device.

The desire to eliminate the disadvantages of PostScript and establish a universal data format for the exchange of digital documents led Adobe to the development of the Portable Document Format (PDF) and the Acrobat software. The triumphant procession of PDF has lasted almost ten years now, receiving a strong impetus from the massive expansion of the Internet and the increased online distribution and use of digital documents.  While the full version of Acrobat has been contributing enormously to the total turnover of Adobe, the Acrobat Reader, used for the display and printing of PDF documents, has been available for free for many years. This encouraged the acceptance and spread of PDF.

PostScript and PDF are closely related and have shared a somewhat parallel development. However, they have a different focus. Both formats are based upon the description of graphic contents, independent of a certain device. In simpler words: Anything that can be drawn or printed can also be expressed in PostScript or PDF. While PostScript is optimized for the printing of data, PDF offers additional qualities that facilitate the use of documents on the screen,  as well as their worldwide exchange. When creating the PDF file format, the developers focused on Adobe's own graphics program Illustrator. This was first launched in 1988 and worked with a scaled-down version of PostScript for the storage of graphics. The resemblance
between the Illustrator commands and those in PDF still exist today.

As is common in the computer industry, PostScript and PDF have undergone  constant revision and further development. Since PostScript is predominantly implemented in hardware (printers, exposure machines and other devices), while Acrobat/PDF are purely software solutions (if you ignore the few PDF-capable devices), the development of these two formats differed in terms of speed. In 20 years of existence, three versions of PostScript were published, which are referred to as PostScript Level 1, 2, and 3. PostScript Level 3 was renamed Adobe PostScript 3 by Adobe's Marketing department. In technical documents, it is often referred to as LanguageLevel 3.  There have been already 5 versions of Acrobat in less than ten years. While the Acrobat versions are numbered all the way through five, the respective PDF version numbers are 1.0 to 1.4. This indicates that the changes in the file format have not been grave or incompatible to each other, but rather smooth and backwards compatible.

Source:
Thomas Merz / Olaf Druemmer: "Die PostScript & PDF-Bibel""
(Munich: PDFlib GmbH, 2002), 2nd edition, pp. 1-2.

This book is only available in German.

We thank the dpunkt Verlag, Heidelberg, for their consent to publish and translate this excerpt. For further information on this title check http://www.dpunkt.de.