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From: neff@hp-vcd.HP.COM (Dave Neff)
Newsgroups: comp.periphs.printers
Subject: Re: Slow Graphics to DeskJet from WP5.1
Message-ID: <980008@hp-vcd.HP.COM>
Date: 22 Mar 91 19:07:26 GMT
References: <69280003@hpcupt1.cup.hp.com>
Organization: Hewlett Packard, Vancouver, WA
Lines: 46

Regarding slow graphics print to DeskJet+ or DeskJet 500:

The real problem with some "warmed over LaserJet" drivers for the
DeskJet is the drivers use continually varying "graphics margins"
(technically graphics widths and start printing at a particular cursor
position) as a sort of data compression.  Whenever the graphics print
width or left margin varies, the DeskJets must flush current graphics and
then re-allocate memory.

The DeskJet has real data compression modes and can print graphics
as well as mixed text and graphics quite fast with properly written
drivers.  We try to encourage the software vendors to meet certain
minimum performance guidelines, but of course we can't force them
to "do it right".  Anything more than about 2 minutes per page for
any type of output likely suggests a driver problem (for the DeskJet+
and DeskJet 500, the Classic is quite slow in graphics for other reasons).

The particular offending escape sequences are Esc *r1A (start graphics
at current cursor position, compared to Esc *r0A which means start graphics
at the left paper edge) and Esc *r#S (set raster width).  If the raster
width is set once per page, and the left cursor position doesn't vary
over the page the DeskJets do just fine.  But when these parameters
vary every few raster rows, then performance goes down the tube.
Proper use of data compression eliminates any real advantage of using
these kinds of tricks (that can achieve a measure of data compression
on laser printers).

Generally, WordPerfect has been pretty good about modifying their driver
to support the DeskJet printers.  I'm surprised to hear they are blaming
the printer and not trying to improve the driver.  This is contrary to
what I have heard from our own support people.  In all fairness to
WordPerfect and other software packages, it is quite tricky
to do merged text and graphics correctly to the DeskJet printers.
There is an algorithm that works and give good performance, but it
is often difficult for some word processors to implement. To compound
the problem, the DeskJet Classic was so slow for graphics it sometimes
masked driver problems that vendors have still not fixed for the now
faster Plus and 500.

Dave Neff
neff@hpvcfs1.HP.COM

Disclaimer: I don't work in HP support.  I write printer firmware
(including some of the code for the DeskJet+ and DeskJet 500).  The
above are my opinions based on my knowledge of the printers and don't
necessarily reflect official HP opinions.