PostScript is a page description language developed by Adobe Systems in the early 1980s. It was originally created by John Warnock and Charles Geschke as a way to control the output of high-resolution printers. The name PostScript reflects its role as a scripting language used after the fact to describe how text and images should appear on printed pages.
The language operates on a stack-based architecture, allowing commands to be pushed onto a stack and executed in a sequence, which makes it versatile for a variety of graphic and text rendering tasks. One of the most notable features of PostScript is its ability to describe vector graphics, which can be scaled to any size without loss of quality. This characteristic is especially important for printing graphics and images in high fidelity, making PostScript a standard in the desktop publishing industry.
PostScript also gained prominence due to its capability to define complex page layouts and typography. It includes commands for drawing shapes, filling areas with color, and rendering text, making it powerful for creating intricate designs. The language is both device-independent and resolution-independent, meaning that a PostScript file can be generated once and printed on any printer that supports it without needing to be rewritten for different devices.
The introduction of PostScript revolutionized the printing and publishing industries, providing a means for designers and printers to ensure that their creations appeared consistently across various devices. It paved the way for desktop publishing software and has been instrumental in the creation of books, magazines, and other printed materials.
As PostScript files are typically ASCII text files, they can be generated by various software applications, including graphic design and word processing programs. This feature made it easier for users to create and share documents across different platforms and systems. Additionally, PostScript can also be used to create interactive graphics and presentations.
In the context of programming, PostScript is considered a programming language due to its ability to define functions, control flow, and manipulate data. It allows for the creation of procedures and can be extended with user-defined functions, making it adaptable for various tasks beyond mere page description.
PostScript remains in use today, especially in professional printing environments. It is often found in conjunction with PDF (Portable Document Format), which was also developed by Adobe and incorporates PostScript as part of its internal structure. The two formats are complementary; while PostScript serves as a language for printing, PDFs offer a more user-friendly format for sharing documents.
Here’s a simple example of PostScript code that draws a rectangle:
%!PS
/newpath
100 100 moveto 200 100 lineto 200 200 lineto 100 200 lineto closepath
stroke
showpageIn this example, the code sets up a new path and draws a rectangle at specified coordinates, ultimately producing a visual output when processed by a PostScript-compatible printer.
Overall, PostScript continues to play a vital role in the realm of graphic design and printing, providing designers with the tools to produce high-quality printed materials that are consistent and reliable across various devices. Its legacy and influence remain significant, making it a foundational technology in the evolution of digital printing and publishing.