Newsgroups: comp.lang.postscript
Path: utzoo!sq!lee
From: lee@sq.sq.com (Liam R. E. Quin)
Subject: Re: Bitmap decompression wanted
Message-ID: <1990Jul8.215653.22633@sq.sq.com>
Organization: SoftQuad Inc.
References: <8561@cognos.UUCP> <1990Jul5.205445.8084@kth.se>
Date: Sun, 8 Jul 90 21:56:53 GMT
Lines: 24

donc@cognos.UUCP wrote:
> [...] sending large bitmaps to my PostScript printer is one of my biggest
> bottlenecks.  I read in the 'green' book that compressing a bitmap first
> and decompressing it in [the printer] could save some time.

d87-jse@kth.se (Joakim Sernbrant) warned:
> I have spent many hours on this matter.  I have tried runlength encoding
> and packing six bits into each byte in the image. [...] Everything I've
> tried has actually been mush slower than normal.

Also, if you don't give _image_ a single lump of data, you might get visible
horizontal streaks or lines at the border between the bands.  On the other
hand, if you send the data and build up data to give to image in one huge
lump, beware of having two copies lying around, or you might run out of
stack space.  It is very hard to make the printer run fast enough for
this to be worth while, particularly if you use 19200 baud or faster...
Of course, on the faster printers such as the Agfa PS400, or maybe
Xerox's new printer, this shouldn't be a problem...

Lee
-- 
Liam R. E. Quin,  lee@sq.com, {utai,utzoo}!sq!lee,  SoftQuad Inc., Toronto
``Sun. n.s.,  Any thing eminently splendid'' [Johnson's dictionary (1837)]