[printing-discuss] Re: [Inkjet-list] Device capabilities?

Patrick Powell papowell at astart.com
Thu Apr 4 07:19:00 PST 2002


> > ...
> >>As for IP issues, from the perspective of a driver developer
> >>all I can say is that generally what printer manufacturers  find new or
> >>innovative has been done dozens of times before  by their competitors
> >>already, or in other fields.  That said, I know I'm shouting into the
> >>wind...
> > 
> > Someone has to be first, though, and it *is* a very fiercely competitive
> > area.  But eventually, sure, the new tech becomes commonplace.
>
> I'll tell you, in 8 years of writing commercial drivers and 7 years
> before that just fooling around, I haven't seen anything innovative
> in the printer commands sent to a printer.  If anything, printers
> have become *less* capable in order to print costs down - all of the
> innovation seems to be happening in the hardware and vendor-supplied
> printer drivers, not in the commands sent to the printer...
>
> -- 
> ______________________________________________________________________
> Michael Sweet, Easy Software Products                  mike at easysw.com
> Printing Software for UNIX                       http://www.easysw.com

The main driving force behind a lot of these changes is, of course,
financial.  The printing vendors discovered that in order to make
'good quality' printing they had to rasterize the incoming data
and then drive an extremely complex mechanism with VERY precise
timing tolerances.  I went to a talk at HP once (disguised by
wearing a T-shirt), and listened with mouth agape as somebody
described how inkjets squirt ink out.  You REALLY don't want to
know.  I think most of it is faith and black magic, execept when
doing color and it is definately Terry Pratchet 'Color of Magic'
wizardry.

Given this,  if you can have users do the rasterization,  then you
cut WAY down on the work needed to generate output.  If you have them
do rasterization,  why not skip all the crud and have a really simple
data format for transferring information?  This makes life easy for
the generating program as well as the hardware/software in the printer
that uses the raster format.  The problem here is that you need to make
sure that you can transfer the raster image at the rate needed by the
printer to produce nice images.  This is a whole problem topic in itself.

For high end printing you have another problem: speed.  Here you
need to be able to handle 'PostScript' or PJL or PCL in an efficient
manner and rasterize it as fast as possible.  This leads to the
desire to have as LITTLE complexity in the PostScript as possible,
so you carefully design your 'PostScript Generator Code' AKA 'the
printer driver' to produce the Worlds Stupidest PostScript.  Stupid
is good.  Gsaves/rotates/scales/imagecopies are EVIL as they slow
things down.  Also, you redefine all the operations you can as one
or two letter commands (or functions,  you know what I mean) so
you can generate Really Small Stupid Postscript.

Finally, you realize that RSSP needs to be formallized,  copyrighted,
and specified,  so you call it 'PDF'.  (Ok ok, so I am a bit cynical.)

Apple has decided to generate PDF as raster output format.  It kind of
makes sense.  If your vocabulary does not have the word for 'expensive
graphics operation' then you probably will not use it.  Thus,  you will
get output that will be efficient to print.  *** I did not say portable ***
But that is another issue.

Patrick Powell                 Astart Technologies,
papowell at astart.com            9475 Chesapeake Drive, Suite D,
Network and System             San Diego, CA 92123
  Consulting                   858-874-6543 FAX 858-279-8424 
LPRng - Print Spooler (http://www.lprng.com)




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