chuq@plaid.UUCP (05/30/87)
Date: Thu, 28 May 87 17:04:48 PDT From: hoptoad!gnu (John Gilmore) > Postscript is so incredibly poor at handling bit images that I'm > about to die... > how about if anyone is doing a faster, > less expansive Postscript which emphasises speed for bit mapped > graphics (if seems odd that postscript is SOOO poor at doing > something that so many of us need to do)? Actually, PostScript is not bad at bit images. The problem really lies with the "absolutely ascii or die" attitude taken by the PostScript designers. To dump a bitmapped image to a LaserWriter, it must be converted to ascii. The traditional way (recommended by the PostScript manuals) is to convert it to hexadecimal, immediately doubling its size, and the time required to dump it to the printer. Now it would be easy to just dump the raw bits to the printer (preceded by a PostScript program that would read them in and print them) except that Adobe screwed up the serial port driver on the LaserWriter. They reserve a bunch of control characters, which are interpreted by the driver, and these cannot be turned off by a PostScript program. If a bit pattern in your bitmap happens to match control-T, the driver outputs a status message and doesn't pass the character up to PostScript. This misfeature also prevents you from writing a PostScript program which emulates common printers, e.g. an Epson in graphics mode. (You could download the emulator once per power-cycle and print for days or weeks with your host thinking it was talking to an Epson.) It also doesn't let you run compression on the data you are sending to the printer. A lot of bit maps compress very well, and PostScript has the expressive power to write a decompresser (like zcat) without too much trouble. Adobe *did* fix the drivers in the LaserWriter Plus so that they will run at more than 9600 baud, but they did *not* fix the trapping of control characters. I think it's against their religion or something. I don't know if other PostScript printers have this problem. I'm stuck with a LaserWriter. Let me know if you have a printer without this problem, I might buy one and junk the LW. ---------------------------------------- Submissions to: desktop%plaid@sun.com -OR- sun!plaid!desktop Administrivia to: desktop-request%plaid@sun.com -OR- sun!plaid!desktop-request Paths: {ihnp4,decwrl,hplabs,seismo,ucbvax}!sun Chuq Von Rospach chuq@sun.COM Delphi: CHUQ Now, where did my ex-wife put my Fairy Dust?