Very Quick Introduction to Ghostscript

Ghostscript is a PostScript interpreter.  PostScript is a language, not a graphic file format.  A PostScript file is really a program, not graphical data.  The difference is that by looking at a PostScript file you (or an application) cannot easily tell what the file represents.  Instead, you must run the file to see what it does.  Generally, the result of running a PostScript program is to draw marks on a graphical page.  (There are PostScript programs that don't draw anything at all!   Some are even distributed as test files with Ghostscript.)  This works well for printers but is a bit odd for interactive window systems.

Think of Mac GS Viewer as a virtual printer:  Every time you open a file, asking Ghostscript to run it as a PostScript program, the application creates a new sheet of 'paper' and displays it in a window.  You can see the program execute as it places marks on the 'paper' in the window (unless your computer is much faster than mine!)  Once the program is done, the page is 'ejected' from the printer.  However, the application leaves the window on the screen so you can continue to look at it (and scroll it, save it, etc.).  But remember, at this point, the page is out of the printer and Ghostscript can no longer change it.  If you want to change some parameter (such as scaling), you must change the parameter and then re-open, and thus re-run, the PostScript file.

Please see the file readme and the files that end in .doc in the files folder for more information.