We all know there’s a thing called Postscript in the trade of designing and creating printed matter, but fewer of us know what it is and fewer still how it works.
But without it, none of us would have a job. The creation of publishing and print design would still be in the hands of a select few craftsmen and creative artisans who knew more about the difference between HB and 2B than raster and pixels.
The pre-Postscript days where when the extent of desktop outputting meant the pinwheel of your pin printer sliding steadily back and forth sounding like an enraged wasp.
And no, it’s not just laser printers that have bought us to the stage where a colour runoff is virtually indistinguishable to a four colour process output (to the casual observer, anyway).
The imaging mechanics of a laser printer or film imagesetter are extraordinary, but something has to tell your printer where to squirt ink or electrify the drum. That something is a page description language, and the one most used by designers and graphics users is Postscript.
Among the few people who know what Postscript actually is, fewer still know it was the product that drove the foundation of one of the most recognised names in the graphics field; Adobe.
After adapting work done by computer scientists in the late seventies at Xerox (original home of the mouse — that other IT revolution they sold for a song), Adobe founders John Warnock and Chuck Geschke opened their doors with their new product; a language specifically designed to optimise graphic output.
Speak the Right Language
Postscript isn’t a program, a standard or a command, it’s an ‘interpreted, stack-based language’. Theoretically, you could use it to write any computer program just like C++, VB, COBOL and all those names you see under computer contracts of the positions vacant section for $200K a year. Someone has in fact used Postscript to hand code an entire web server.
But after its third iteration (Adobe are currently working with Postscript 3), it’s been continually optimised for one purpose; outputting of images, be they fonts or graphics of any colour or shade.
Postscript is a language that can be interpreted like any other. To prove it to yourself — and see what Postscript looks like — create a Postscript file on your desktop (you do it by saving your print file to disk instead of sending it to your output device). Open it with your word processor and it’ll be a huge but quite ordered jumble of code — it’s what your computer will use to speak to your printer as it tells it where to put the elements of your page.
Where do you Get It?
Unless you’re an output device manufacturer like Apple or Heidelberg, you’re not Adobe’s target market for selling Postscript, so don’t wait around for them to inundate you with spam for it.
If you own an inkjet or laser printer, chances are you already have it. Adobe’s customers for Postscript are anyone who’s in the business of producing machines to deliver output from computer graphics tools (printers and printing presses).
Adobe owns the rights to the language. They supply translators that can interpret it to vendors who make presses. Graphic tools vendors like Quark, Adobe (obviously) and whoever else wants their products to print professional quality documents build the capability to write files in the Postscript language into those products. And we’re not talking about a select few — according to Adobe, there’s over 5000 of them.
So printing a document is simply sending a Postscript file to your desktop laser or a four-colour process filmsetter and the machine receiving it will know how to read it.
And being device-independent, the theory is that it doesn’t matter which platform or application the document has come from (or is going to). In fact, if you had the expertise (and far too much time on your hands), you could sit down with a text editor and hand code an entire Postscript file to produce press-ready artwork.
It’s all in the Script
Talking about imaging before and after Postscript is like talking about the difference between Photoshop and Illustrator. If you output a Photoshop file larger than the size it’s set up for, you get pixelation; badly.
Printing devices used to be the same. The only message your computer sent to your printer was a plan of which pixels to fill in and which ones not to; it would have been exhaustive (if not impossible) to calculate which new pixels to fill in to preserve the resolution as the image grew.
We all know now how Illustrator made a difference; being raster rather than pixel based, the image size is immaterial.
Postscript takes advantage of the same idea. By being ‘points based’, the same Postscript file could be used to create a standard sized business card and a three-storey billboard.
With on the fly rasterisation, it uses the same principle as scalable fonts to instantly redefine the number of dots filled in on the output device for maximum resolution — whether screen to press.
Postscript has become an integral part of the way computer designers work, taking quiet steps to streamline the entire design and print process. And it’s done it patiently in the wings while sexier technologies continually hog centre stage.
In fact, an Adobe spokesman even noted that Postscript is credited with reducing the number of operators needed to get a design from concept to completion from 33 to just three — including the press operator.
And like its higher profile cousin, PDF, rapid standardisation in the industry together with Adobe’s considerable development grunt (even back when they were a two-man team) means that Postscript will be under the hood of your outputting capabilities for a long time yet.