Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!microsoft!ericbi
From: ericbi@microsoft.UUCP (Eric BIDSTRUP)
Newsgroups: comp.lang.postscript
Subject: Re: 9600 bps bottleneck on Laserwriter Plus
Summary: Data compression for bitmaps is great in theory,
	 but doesn't cut it in reality
Message-ID: <10213@microsoft.UUCP>
Date: 10 Jan 90 15:28:41 GMT
References: <3495@hub.UUCP> <1990Jan10.042555.19571@grian.cps.altadena.ca.us>
Organization: Microsoft Corp., Redmond WA
Lines: 28

In article <1990Jan10.042555.19571@grian.cps.altadena.ca.us>, alex@grian.cps.altadena.ca.us (Alex Pournelle) writes:
> 
> Implement a postscript decompresso program--one that "unsqueezes" data
> as it comes through the pipe--download it to the printer, then do the
> reverse on the computer.  With some simple escapes, you could massively
> increase throughput on nearly any large file.
> 
> Naturally, you'll have to hand-assemble the code on the host machine, in
> order to see a significant increase in throughput.  But even a 2 to 3x
> compression should be achievable easily, in total wall clock time.
> 
> Comments?
> 	
Sure...
As someone who has attempted to do this before, I recommend you
save yourself the time & energy.  What happened (in my case) was
that the decompression routine took longer to execute & translate
the data stream than simply sending the same data in a non-compressed
format.  I also remember seeing a thread here or on CIS about the
same idea a year ago w/ others having similiar results.  Now that
other printers in the marketplace (the newer HP PaintJet XL for
sure, and I think some of the newer LaserJets) provide commands
to accept bitmapped data in a number of compressed formats, we
can all hope that subsequent revisions of Postscript add commands
to do this to.
-Eric Bidstrup

Disclaimer: Opinions expressed are my own.