Category : DeskTop Publishing in the 1990's
Archive   : GS261EXE.ZIP
Filename : DEVICES.DOC

Copyright (C) 1992, 1993 Aladdin Enterprises. All rights reserved.

This file is part of Ghostscript.

Ghostscript is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY. No author or distributor accepts responsibility
to anyone for the consequences of using it or for whether it serves any
particular purpose or works at all, unless he says so in writing. Refer
to the Ghostscript General Public License for full details.

Everyone is granted permission to copy, modify and redistribute
Ghostscript, but only under the conditions described in the Ghostscript
General Public License. A copy of this license is supposed to have been
given to you along with Ghostscript so you can know your rights and
responsibilities. It should be in a file named COPYING. Among other
things, the copyright notice and this notice must be preserved on all
copies.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

This file, devices.doc, gives more detailed documentation about
certain specific devices for which Ghostscript can produce output.

For an overview of Ghostscript and a list of the documentation files, see
README.

Devices for which this file currently contains documentation:
SPARCprinter
HP DeskJet 500C & 550C
HP PaintJet, XL, and XL300
DEC LJ250
Apple Dot Matrix Printer (and Imagewriter)

### ------------------------- The SPARCprinter ------------------------- ###

This section was written by Martin Schulte.

Introduction
------------

The SPARCprinter is is connected to SPARCStation via a special SBUS card's
video inferface, the picture is composed on the host and only a bitmap is
send to the printer unit.

Together with a SPARCprinter, you always buy (as far as I know) software
that enables you to do postscript-printing on your SPARCPrinter.

So, the need for a Ghostscript-Interface to the SPARCPrinter seems low,
but on the other hand some Postscript drawings are not correctly printed
with SUN's software: on some pages occured a thin vertical line of rubbish
(reproducable), on some Mathematica drawings the text at the axes wasn't
rotated.

I tried all of these with Ghostscript and always got the expected results.

However, replacing proprietary software should never be a bad idea.

The problem is that there has yet been no effort to make the SPARCPrinter-
driver behave like a BSD output-filter, I made my tests using the script
mentioned under Installation.

Installation
------------

Add sparc.dev to DEVICE_DEVS and compile ghostscript as described in
make.doc.

Afterwards, you can use the following script (the way of handling standard
input versus filename-arguments doesn't look very clever, has anyone a
better idea ?) to print if you substitute by the place where you
installed the ghostscript binary:

outcmd1='/vol/local/lib/troff2/psxlate -r'
outcmd2=' -I/home/schulte/gs252 -sDEVICE=sparc -sOUTPUTFILE=/dev/lpvi0 -'

if [ $# -eq 0 ]
then
$outcmd1 | $outcmd2
else
cat $* | $outcmd1 | $outcmd2
fi

Problems
--------

Since /dev/lpvi can only be opened for exclusive use, another job having
opened it (engine_ctl_sparc or another ghostscript as the most probable
canidates) will cause to stop ghostscript with "Error: /invalidfileaccess
in --.outputpage--"

In case of common printer problems like out of paper, a warning describing
the reason will be printed to stdout, the driver will try to access again
and again each five seconds.

Due to a problem with the device-driver (in the kernel) the reason of
printer failure is not always correctly reported to program. This is the
case at least if you open the top cover (Error in the display: E5). Look
to the display at the printer if a "Printer problem with unknown reason"
is reported.

Fatal errors will cause the print-job to be terminated.

### ------------------------------ End --------------------------------- ###

### ------------------- H-P color inkjet printers ---------------------- ###
### (DeskJet 500C, DeskJet 550C, PaintJet, PaintJet XL, PaintJet XL300 ###
### and the DEC LJ250 which can operate in a Paintjet-compatiblme mode) ###

This section was written by George Cameron.

Information and tips on usage for the drivers contained in gdevcdj.c
====================================================================

OVERVIEW:

There are 6 generic drivers contained in the source module:

1 - cdj500: HP DeskJet 500C
2 - cdj550: HP DeskJet 550C
3 - pjxl300: HP PaintJet XL300
4 - pjtest: HP PaintJet
5 - pjxltest: HP PaintJet XL
6 - declj250: DEC LJ250

All of these drivers have 8-bit (monochrome), 16-bit and 24-bit
(colour) and for the DJ 550C 32-bit, (colour, cmyk mode)
options in addition to standard colour and mono drivers.
It is also possible to set various printer-specific parameters
from the gs command line, eg.

gs -sDEVICE=cdeskjet -sBitsPerPixel=16 -dDepletion=1 -dShingling=2 tiger.ps

NB/ The old names cdeskjet, cdjcolor and cdjmono drivers have been retained;
however, their functionality duplicates that available using the above
drivers (and cdeskjet is identical to cdj500), ie. we can use:

gs -sDEVICE=cdj500 -dBitsPerPixel=24 ... for cdjcolor, and
gs -sDEVICE=cdj500 -dBitsPerPixel=1 ... for cdjmono


DEFAULT PAPER SIZE:

If the preprocessor symbol A4 is defined, the default paper size is the
European A4 size; otherwise it is the U.S. letter size (8.5"x11"). Other
paper sizes (including A3 for the PaintJet XL and PaintJet XL300) may be
specified on the command line as explained in the Ghostscript documentation.


DEFAULT BITS-PER-PIXEL:

If the preprocessor symbol BITSPERPIXEL is defined as an integer (see below
for the range of allowable values), this number will be used to define the
default bits-per-pixel (ie. bit depth) for the generic drivers. If the
symbol is not defined, the default is set to 24 bits per pixel. It is
of course still possible to specify the value from the command line, as
described below. Note also that the cdeskjet, cdjcolor and cdjmono
drivers are unaffected by setting this symbol, as their default settings
are predefined to be 1, 3 and 24 respectively.


DESKJET PHYSICAL LIMITS:

Maximum printing width = 2400 dots = 8". The printer manuals say that the
maximum recommended printing height on the page is 10.3", but since this
is obviously not true for A4 paper, and I have been unable to detect any
problems in printing longer page lengths, this would seem to be a rather
artificial restriction.

All Deskjets have 1/2" unprintable bottom margin, due to the mechanical
arrangement used to grab the paper. Side margins are approximately 0.25"
for US Letter paper, and 0.15" for A4.


COMMAND LINE PARAMETERS:

Several printer 'properties' have been implemented for these printers.
Those available so far are all integer quantities, and thus may be
specified as eg.

gs -dBitsPerPixel=32 -dShingling-1 ...

which sets the BitsPerPixel parameter to 32 and the Shingling parameter
to 1.


BITS-PER-PIXEL:

All of the drivers in gdevcdj.c accept a command line option to set the
BitsPerPixel property. This gives considerable flexibility in choosing
various trade-offs between speed/quality/colour etc. The valid numbers
are:

1: This is a standard Ghostscript monochrome driver, and uses
black ink (by installing the separate mono cartridge in
the case of the DeskJet 500C, or automatically for the
other printers)

3: A standard Ghostscript colour driver, using internal
dithering. This is fast to compute and to print, but
the clustered dithering can lose some detail and
colour fidelity.

8: An 'error-diffusion' monochrome driver which uses
Floyd-Steinberg dithering to print greyscale images.
The patterns are much more randomised than with the
normal clustered dithering, but the data files can
be much larger and somewhat slower to print.

16: This is a 'cheaper' version of the following (24-bit)
driver, which generates a Floyd-Steinberg colour dithered
output using the minimum amount of memory (this may be
helpful when using IBM PC's when Ghostscript has not
been compiled using a 32-bit 386-style compiler). The
quality can be almost as good as the 24-bit version.

24: A high-quality colour driver using Floyd-Steinberg dithering
for maximum detail and colour range. However it is very
memory intensive and thus can be slow to compute (and it
tends to produce rather larger raw data files, so they
can also be slower to print).

32: This is for the DeskJet 550C only, which uses the black
cartridge and the colour cartridge simultaneously (ie.
CMYK printing). This printer can be both faster and give
higher quality than the DeskJet 500C, because of the
true black ink. (Note that the 24-bit mode also permits
CMYK printing on this printer, and uses less memory. Any
differences between 24-bit and 32-bit should be very small.)


DESKJET PROPERTIES:

The addional properties available for the DeskJets are:

BlackCorrect (int) /* Colour correction to give
* better blacks when using the DJ500C
* in colour mode, eg. the default of 4
* reduces the cyan component to 4/5
* Range accepted: 0 - 9 (0 = none) */
Shingling (int) /* Interlaced, multi-pass printing
* 0 = none, 1 = 50%, 2 = 25%, 2 is
* best & slowest */
Depletion (int) /* 'Intelligent' dot-removal
* 0 = none, 1 = 25%, 2 = 50%, 1 best
* for graphics?
* Use 0 for transparencies */

PAINTJET XL300/PAINTJET XL PROPERTIES:

PrintQuality (int) /* Mechanical print quality
* -1 = fast, 0 = normal, 1 = presentation
* Fast mode reduces ink usage and uses
* single-pass operation for some media
* types. Presentation uses more ink and
* max number of passes, ie. slowest
* printing for highest quality */
RenderType (int) /* 0 = driver does dithering
* 1 = snap to primaries
* 2 = snap black -> white, others to black
* 3 = ordered dither
* 4 = error diffusion
* 5 = monochrome ordered dither
* 6 = monochrome error diffusion
* 7 = cluster ordered dither
* 8 = monochrome cluster ordered dither
* 9 = user-defined dither (not supported)
* 10 = monochrome user-defined dither ns. */

PAINTJET PROPERTIES:

No additional properties


GAMMA CORRECTION:

One consequence of using Floyd-Steinberg dithering rather than Ghostscript's
default clustered ordered dither is that it is much more obvious that the
ink dots are rather larger on the page than their nominal 1/180" or 1/300"
size (clustering the dots tends to minimise this effect). Thus it is often
the case that the printed result is rather too dark. A simple empirical
correction for this may be achieved by preceding the actual postscript
file to be printed by a short file which effectively sets the gamma for
the device, eg.

gs ... gamma.ps colorpic.ps quit.ps

where gamma.ps is

%!
{0.333 exp} dup dup currenttransfer setcolortransfer

This example sets the gamma for r, g, and b to 3, which seems to work
reasonably well in practice.


GENERAL TIPS:

For all the above printers, the paper is critically important to the
final results. Smoother, less fibrous paper is generally better (and
suggested types are given in the printer manuals). In particular, the
special ink-jet paper can make a big difference; the colours are
brighter, but most importantly, there is almost no colour bleed, even
with adjacent areas of very heavy inking. Similarly, the special coated
transparencies also work well (and ordinary transparencies do not work
at all!)

The unix-lpr.sh provides one example of setting up a multi-option
colour postscript lpr queue on Unix systems, and includes the ability
to choose a range of different colour options and printer accounting
and error logging.


CAVEAT EMPTOR!:

It is not always easy for me to test all of these drivers, as the only
colour printer I have here is the DeskJet 500C. I rely on others testing
drivers for the additional machines and reporting their findings back to
me.

### ------------------------------ End --------------------------------- ###

### ------------------- Apple Dot Matrix Printer ---------------------- ###

This section was written by Mark Wedel.

The Dot Matrix Driver (DMP) driver is a simple driver I wrote. It
could more more efficient, but it seems to print the images fine.

The Dot Matrix Printer was a parallel predecessor to the Imagewriter
printer. As far as I know, the Imagewriter commands are a superset
to those of the Dot Matrix printer, so the driver should work fine at
generating output that can be printed on Imagewriters.

A few notes (from the gdevadmp.c file):

* To print out images, it sets the printer for unidirection printing
* and 15 cpi (120 dpi). IT sets line feed to 1/9 of an inch (72 dpi).
* When finished, it sets things back to bidirection print, 1/8" line
* feeds, and 12 cpi. There does not appear to be a way to reset
* things to initial values.
*
* This code does not set for 8 bit characters (which is required). It
* also assumes that carriage return/newline is needed, and not just
* carriage return. These are all switch settings on the DMP, and
* I have configured them for 8 bit data and cr only.
*
* You can search for the strings Init and Reset (in devdemp.c) to find the
* strings that set up the printer and clear things when finished, and change
* them to meet your needs.
*
* Also, you need to make sure that the printer daemon (assuming unix)
* doesn't change the data as it is being printed. I have set my
* printcap file (sunos 4.1.1) with the string:
* ms=pass8,-opost
* and it works fine.

Mark Wedel
[email protected]

### ------------------------------ End --------------------------------- ###