Talk:Display PostScript

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Disputed

I can't find an authoritative source, but every source I can find (and my own memory) says that Display Postscript was developed at Adobe, and that NextStep was just an early licensee. Even if I'm wrong about this, the vague language about how DPS became an Adobe product indicates nonverified facts, and needs to be resolved into something definite. ---Isaac R 21:26, 21 Apr 2005 (UTC)

DPS was created as a cooperative effort between Adobe and NeXT

I can speak with some authority on this since I did the Adobe side (see /http://theory.kitp.ucsb.edu/~paxton/ for more info on my history). One of my first projects at Adobe, when Steve Jobs was still at Apple and the first LaserWriter was yet to be born, was to make a display driver for PostScript so it could make images directly on the Sun workstation screen. I used that system to create a font outline editing system written in PostScript that we used to make the first Type 1 fonts. So there's a real sense in which "display PostScript" was created at Adobe long before NeXT existed.

But that early DPS wasn't at all up to the job of supporting something like NeXT Step. So there was lots of work still to be done when Jobs contacted Adobe and suggested a project with NeXT. Adobe provided sources for PostScript (except for the sensitive font module), technical support (me), and whatever changes needed from the Adobe side (me, again). The NeXT side of the project was to create something that would actually work for a product-quality, interactive, display based user interface. They did a brilliant job, and it was a pleasure working with them.

Many of the things learned in doing Display PostScript were introduced into the Level 2 version of PostScript. DPS was also an important step toward PDFs.

As to why Apple's Quartz uses PDF rather than DPS, I can only speculate (I was elsewhere when that was going on). My guess is that PDF is simply a better choice than DPS for purely technical reasons. It's not surprising that all the experience with PostScript eventually led Adobe to create something even better. And it's also not surprising that Apple recognized the fact.

--- Bill Paxton, 15 May 2005

Performance?

It was always my impression that even without licensing concerns, DisplayPDF is significantly faster than DPS. It deals with a simpler subset of instructions and doesn't have to be Turing complete. In other words, it's Teh Snappy.

Frankie 13:57, 2005 August 1 (UTC)

Display PDF (I think you mean Quartz, Apple's never called it Display PDF formally), while I don't know if it's faster, does offer other advantages. Like the fact that you can pretty much save directly to PDF from any print dialog, without firing up Acrobat. PDF has a lot of advantages as a document format over PostScript, which I've changed the article to reflect. 142.150.142.28 02:19, 30 August 2005 (UTC)[reply]

Well considering that OS X was much slower at graphics than Rhapsody (I ran them both) the speed argument is, well, arguable. The differences in terms of "theoretical performance" seem limited IMHO, I doubt that the decoding in the interpreter represents any sort of real-world time compared to actually running the math and pushing the bits across the bus. As to the "advantages" of saving directly to PDF, one could of course do that with DPS as well. The two are very similar in concept, and generally trivial to convert between (with exceptions, of course).Maury 22:32, 18 April 2006 (UTC)[reply]

“While early versions of Postscript display systems were developed at Adobe, the full implementation of Display PostScript was developed in cooperation with Adobe Systems[…]” Shouldn’t the first “Adobe” be “NeXT”? “Modern full-color displays with no halftones have made this idea mostly obsolete.” As far as I can see, this is wrong. Quartz has patterns with phase shifting, which are basically the same thing. (The standard window background is an obvious example of a pattern.) -Ahruman 11:15, 28 March 2006 (UTC)[reply]

Fixed. Maury 22:32, 18 April 2006 (UTC)[reply]

NeWS and Display PostScript are complete different implementations of Adobe's PostScript specification

The sentence "the full implementation of Display PostScript was developed for Sun Microsystems' NeWS in 1986" is incorrect. NeWS was not Display PostScript. NeWS was an implementation of PostScript that rendered on the screen, implemented by James Gosling, David S H Rosenthal, and others at Sun, but Display PostScript is a totally distinct product that shares absolutely no code with NeWS.