TITLE
    System 7 LaserWriter Driver: How to Shrink PostScript Files
Article ID:
Created:
Modified: 		9530
1/17/92
2/7/00
TOPIC

    With System 6, I could use Command-K to dump a PostScript image with Laser Prep, or Command-F to dump a PostScript file without Laser Prep.

    With System 7, I can't seem to find a way to dump the PostScript file without the Laser Prep. Now an option in the print dialog allows me to select "Postscript File." This provides the same function as Command-K. But is there a way I can exclude Laser Prep as I did with Command-F?

    Also, is there any way to make the generated PostScript file any smaller than it is?

DISCUSSION

    There is no Apple solution yet for generating PostScript files without headers under System 7. The latest improvement is the version 7.1 LaserWriter driver, which improves printing performance. But we don't have a solution to the problem of extremely large saved files.

    The large saved file situation is caused by two major changes from the driver versions prior to 7.0 (excluding 6.1, which is really an old version of 7.0.):

    - The addition of TrueType, and

    - The need to prevent "laser wars."

    TrueType fonts require the TrueType scaler on the destination printer. Because the driver doesn't know anything about the final destination when saving to a file, it saves everything that might be necessary. This can add several hundred kilobytes to the file's size, and that's with only a couple of fonts. The scaler itself adds well over 100K.

    Laser war problems at customer sites with several different driver versions motivated a change in the prep dictionary downloading. Prior to System 7, the first user to print downloaded their version of Laser Prep semi-
    permanently (outside of the server loop; remaining until a power cycle). Subsequent print jobs from other users would query the LaserWriter and see that the prep information already existed. If the query found an incompatible version, their prep dictionary replaced the existing one. If the existing version was compatible, everything worked fine. The prep dictionary is referenced from the LaserWriter driver's output as a library of procedures. If the referenced routines don't exist the print job will fail.

    The System 7 method sends the prep information along with each print job. Since it isn't downloaded semi-permanently, it's always saved with a file because the information is still required. In addition to increasing the file size, this conflicts with non-Apple laser printers (usually connected to workstations or minis) that use substitute prep dictionaries. Since the prep dictionary isn't always present in the LaserWriter, the Command-F option wouldn't work anyway without adding the header code.

    A shareware program called Trimmer allows you to select fonts you want excluded from saved files. It also allows the exclusion of the TrueType scaler. Trimmer also provides an option of excluding the Laser Prep header from the PostScript file, simulating the Command-F option from System 6.x. It provides a good way to eliminate unneeded data from saved files. But it's an unsupported non-Apple solution.

Document Information
Product Area: Apple Software; Printers
Category: Printer Software
Sub Category: LaserWriter

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