From PostScript to PDF: The Evolution of Page Description Languages

In the 1970s, the world of printing was dominated by quirky languages specific to each printer and typesetter. This was the era when engineers at Xerox Parc set out to create a better solution – Interpress, a language for controlling Xerox laser printers. However, this attempt at commercialization failed, leading John Warnock and his boss Chuck Geschke to form a company called Adobe.

The Birth of PostScript

Adobe's early success came with the introduction of PostScript, a page description language designed specifically for laser printing. PostScript was like Forth, a programming language that used words tailored for page layout and laser printing. The key selling points of PostScript were:

* Easy access to printer specifications * Licensing flexibility for printers, allowing them to use the technology in their devices without having to develop it themselves * Device independence, enabling files created with one type of device to be used with another

These features made PostScript a popular choice among printer makers and computer users alike.

The Impact on Desktop Publishing

The introduction of PostScript had a profound impact on the world of desktop publishing. With PostScript, companies like Aldus developed software that allowed users to create professional-looking documents using their computers. The first such software was PageMaker, which revolutionized the industry and paved the way for future innovations.

The Evolution of PostScript

Over time, Adobe continued to improve PostScript with new features and updates. One significant milestone was the release of PostScript Level 2 in 1991. This update addressed many of the limitations of the original PostScript and introduced improved support for color separation, compressed images, and custom fonts.

However, this also led to a problem – competitors began releasing their own versions of these features before Adobe could. To address this issue, Adobe dropped the "Level" designation from its naming convention and released PostScript 3.

The Emergence of PDF

PostScript 3 introduced significant changes to the page description language, including support for 12-bit colors and PDF files. While PostScript remains a powerful tool for controlling printers, PDF has become the dominant format for describing pages.

The key difference between PostScript and PDF is that PostScript focuses on how to create a page, while PDF describes what the page should look like. This means that PDFs can contain layers and transparency, which were not possible with PostScript.

Working with PostScript

PostScript is often misunderstood as being a programming language. However, its syntax and structure are similar to Forth, making it accessible to developers who are familiar with these languages.

To work with PostScript, you can use software tools like GhostScript, which allows you to create and render PostScript programs on your computer. GSView is another useful tool for displaying PostScript files on screen or printing them to any connected printer.

For those who want to delve deeper into the code, Adobe provides extensive documentation on PostScript programming.

The Legacy of PostScript

While PDF has become the standard format for page description, PostScript remains a powerful tool for controlling printers. Its evolution over time has led to significant improvements in printing quality and flexibility.

Today, many printers support PostScript, making it possible for users to create high-quality documents using this legacy language.