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Thread: Laser Printer as accelerator?

  1. #11

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    I still have my laserjet III with a PacificPage postscript cartridge. Traveling somewhere, I stumbled across a Postscript language reference book in of all places an airport bookstore. Somewhere I still have that book, it was quite a few hundred pages. I came away with the thought that postscript was "complicated".

  2. #12
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    Quote Originally Posted by glitch View Post
    Wasn't clear, I don't work with him anymore so I can't follow up, but from the story he told, he was having the PostScript engine in the printer do calculations that ended up coming out in the printed document because the printer was faster at doing it than his desktop was.
    I'm not saying I don't believe..it's just one of those things I'd like to see to believe

  3. #13

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    The key to understanding how to offload computations to a Postscript printer is realizing that Postscript is a Turing-complete programming language. When you print to a Postscript printer, what you're doing is sending the printer a Postscript program which, when executed by the printer, renders the desired output. Postscript was designed primarily for rendering graphics, but it can be used to perform arbitrary computations.

    One of the advantages of Postscript vs. other contemporary schemes was that you could define an image in a manner which is independent of the resolution of whatever printer you use. If you create a Postscript program which draws a circle, that circle will be rasterized at 300 DPI on a 300 DPI printer, or at 2400 DPI on a 2400 DPI printer, for example. So, you could create vector graphics suitable for being blown up to billboard size, yet print proofs from the same file on your little 300 DPI laser printer at home.

    For a very simple example of how one might offload calculations to the printer, consider these two examples:

    • Print "5" in a particular font at a particular location on the page.
    • Add 2 to 3, then print the result in a particular font at a particular location on the page.


    Both of those examples produce the same printed output, but in the second example, the printer itself calculates the number to be printed.

    As another example, you could declare a function in a Postscript program which draws a logo, and then call that function in a loop which scales, rotates, and translates the result in a calculated manner to render a bunch of copies of the logo in a spiral.

    Here's something I found in a Google search which may shed some light on how you might compute arbitrary stuff on any Postscript printer:

    http://www.mostlymaths.net/2008/12/q...-tutorial.html

  4. #14
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    Again, have a look at Don Lancaster's work.

    PS normally does its computation in 32-bit IEEE floating point. PS is a stack-oriented language, like FORTH. So, you can do quite a bit with it. Don gives lots of examples.

  5. #15

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    Robert Sedgewick's Algorithms books (at least the Pascal , C and C++) was done in such a fashion.
    If the illustration in the book should depict a tree undergoing rotation they wrote a program in Pascal and instrumented
    it such that the datastructure's current structure at an event was dumped. The tree was sent
    in a symbolic form to the postscript engine in the printer which then did the layout of the picture.

    The illustrations is beautiful.

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